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  • 151. Del Litto, Raffaella
    et al.
    Benessere, Vincenzo
    Ruffo, Francesco
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Carbohydrate-Based Pyridine-2-carboxamides for Mo-Catalyzed Asymmetric Allylic Alkylations2009In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 9, p. 1352-1356Article in journal (Refereed)
    Abstract [en]

    Bis(pyridine-2-carboxamides) were prepared from 1,2-diamines obtained from alpha-D-ghlcose and alpha-D-mannose. The ligands were assessed in molybdenum-catalyzed asymmetric allylic alkylations (AAA) by using both methyl (E)-3-phenyl-2-propenyl and methyl rac-1-phenyl-2-propenyl carbonates and dimethyl malonate as nucleophile under microwave irradiation. High enantioselectivity (99 % ee) and high regioselectivity (49:1 in favour of the branched isomer) were observed in reactions of the linear achiral substrate in the presence of 10 mol-% of a catalyst prepared from a ligand derived from glucose. Somewhat lower enantioselectivity (up to 96 % ee) was observed in reactions with the branched racemic carbonate by using the same ligand. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

  • 152.
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Photochemical Surface Functionalization: Synthesis, Nanochemistry and Glycobiological Studies2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis mainly deals with the development of photochemical approaches to immobilize carbohydrates on surfaces for glycobiological studies. These approaches have been incorporated into a number of state-of-the-art nanobio-platforms, including carbohydrate microarrays, surface plasmon resonance (SPR), quartz crystal microbalance (QCM), atomic force microscopy (AFM), and glyconanomaterials. All the surfaces have displayed good binding capabilities and selectivities after functionalization with carbohydrates, and a range of important data have been obtained concerning surface characteristics and carbohydrate-protein interactions, based on the platforms established. Besides, a variety of non-carbohydrate and carbohydrate-based molecules have been synthesized, during which process the mutarotation of 1-glycosyl thiols and the stereocontrol in 1-S-glycosylation reactions have been thoroughly studied.

  • 153.
    Deng, Lingquan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Norberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Uppalapati, Suji
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereoselective synthesis of light-activatable perfluorophenylazide-conjugated carbohydrates for glycoarray fabrication and evaluation of structural effects on protein binding by SPR imaging2011In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 9, no 9, p. 3188-3198Article in journal (Refereed)
    Abstract [en]

    A series of light-activatable perfluorophenylazide (PFPA)-conjugated carbohydrate structures have been synthesized and applied to glycoarray fabrication. The glycoconjugates were structurally varied with respect to anomeric attachment, S-, and O-linked carbohydrates, respectively, as well as linker structure and length. Efficient stereoselective synthetic routes were developed, leading to the formation of the PFPA-conjugated structures in good yields over few steps. The use of glycosyl thiols as donors proved especially efficient and provided the final compounds in up to 70% total yield with high anomeric purities. PFPA-based photochemistry was subsequently used to generate carbohydrate arrays on a polymeric surface, and surface plasmon resonance imaging (SPRi) was applied for evaluation of carbohydrate-protein interactions using the plant lectin Concanavalin A (Con A) as a probe. The results indicate better performance and equal efficiency of S-and O-linked structures with intermediate linker length.

  • 154.
    Deng, Lingquan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Xin
    Uppalapati, Suji
    Norberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dong, Hai
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Joliton, Adrien
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereocontrolled 1-S-glycosylation and comparative binding studies of photoprobe-thiosaccharide conjugates with their O-linked analogs2013In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 85, no 9, p. 1789-1801Article in journal (Refereed)
    Abstract [en]

    The use of thioglycosides and other glycan derivatives with anomeric sulfur linkages is gaining increasing interest, both in synthesis and in various biological contexts. Herein, we demonstrate the occurrence and circumvention of anomerization during 1-S-glycosylation reactions, and present highly efficient and stereocontrolled syntheses of a series of photoprobe-thiosaccharide conjugates. Mutarotation of glycosyl thiols proved to be the origin of the anomeric mixtures formed, and kinetic effects could be used to circumvent anomerization. The synthesized carbohydrate conjugates were then evaluated by both solution- and solid-phase-based techniques. Both binding results showed that the S-linked glycosides interact with their cognate lectins comparably to the corresponding O-analogs in the present cases, thus demonstrating the reliability of the solid-support platform built upon our photo-initiated carbohydrate immobilization method for probing protein bindings, and showing the potential of combining these two means for studying carbohydrate-protein inter-actions.

  • 155. Detz, R. J.
    et al.
    Sakai, K.
    Spiccia, L.
    Brudvig, G. W.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology, China.
    Reek, J. N. H.
    Towards a Bioinspired-Systems Approach for Solar Fuel Devices2016In: ChemPlusChem, ISSN 2192-6506, Vol. 81, no 10, p. 1024-1027Article in journal (Refereed)
  • 156. Diaz-Alvarez, Alba E.
    et al.
    Mesas-Sanchez, Laura
    Dinér, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Uppsala University, Sweden.
    Access to Optically Pure beta-Hydroxy Esters via Non-Enzymatic Kinetic Resolution by a Planar-Chiral DMAP Catalyst2014In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 19, no 9, p. 14273-14291Article in journal (Refereed)
    Abstract [en]

    The development of new approaches to obtain optically pure beta-hydroxy esters is an important area in synthetic organic chemistry since they are precursors of other high value compounds. Herein, the kinetic resolution of racemic beta-hydroxy esters using a planar-chiral DMAP derivative catalyst is presented. Following this procedure, a range of aromatic beta-hydroxy esters was obtained in excellent selectivities (up to s = 107) and high enantiomeric excess (up to 99% ee). Furthermore, the utility of the present method was demonstrated in the synthesis of (S)-3-hydroxy-N-methyl-3-phenylpropanamide, a key intermediate for bioactive molecules such as fluoxetine, tomoxetine or nisoxetine, in its enantiomerically pure form.

  • 157. Ding, Xin
    et al.
    Gao, Yan
    Ye, Lu
    Zhang, Linlin
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Assembling Supramolecular Dye-Sensitized Photoelectrochemical Cells for Water Splitting2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 23, p. 3992-3995Article in journal (Refereed)
    Abstract [en]

    The method used to assemble dye-sensitized photoelectrochemical (DS-PEC) devices plays a vital role in determining its photoactivity and stability. We report a simple and effective method to assemble supramolecular DS-PECs introducing PMMA as support material and a catalyst modified with long carbon chains as photoanodes. The long carbon chains in combination with PMMA allow to better immobilize the catalyst. DS-PECs obtained by this simple method have display excellent photoactivities and stabilities. A photocurrent density of 1.1mAcm(-2) and a maximum IPCE of 9.5% have been obtained with a 0.2V vs NHE external bias.

  • 158. Ding, Xin
    et al.
    Gao, Yan
    Zhang, Linlin
    Yu, Ze
    Liu, Jianhui
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Artificial photosynthesis: A two-electrode photoelectrochemical cell for light driven water oxidation with molecular components2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 149, p. 337-340Article in journal (Refereed)
    Abstract [en]

    An efficient two-electrode molecular PEC was assembled, in which a photoanode was constructed using a co-adsorbed method with a molecular photosensitizer (PS) 1 and a molecular catalyst 2 on TiO2-sintered FTO electrode (TiO2(1 + 2)). Without applied bias against a reference electrode, the system achieves remarkable photocurrent densities and carries out light driven water oxidation as evidenced by Clark electrode measurements in solution. A photocurrent density of 70 mA/cm(2) has been obtained within 10 s illumination time, and a TON of about 220 was obtained with a maximum turnover frequency (TOF) of ca. 4 min(-1) within the initial 5 minutes illumination duration.

  • 159. Ding, Xin
    et al.
    Gao, Yan
    Zhang, Linlin
    Yu, Ze
    Liu, Jianhui
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Visible Light-Driven Water Splitting in Photoelectrochemical Cells with Supramolecular Catalysts on Photoanodes2014In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 4, no 7, p. 2347-2350Article in journal (Refereed)
    Abstract [en]

    By using a supramolecular self-assembly method, a functional water splitting device based on a photoactive anode TiO2(1+2) has been successfully assembled with a molecular photosensitizer 1 and a molecular catalyst 2 connected by coordination of 1 and 2 with Zr4+ ions on the surface of nanostructured TiO2. On the basis of this photoanode in a three-electrode photoelectrochemical cell, a maximal incident photon to current conversion efficiency of 4.1% at similar to 450 nm and a photocurrent density of similar to 0.48 mA cm(-2) were successfully obtained.

  • 160.
    Dinér, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yttrium from Ytterby2016In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 8, no 2, p. 192-192Article in journal (Refereed)
  • 161. Domen, K.
    et al.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology, China .
    Editorial2013In: Catalysis Science and Technology, ISSN 2044-4753, Vol. 3, no 7, p. 1659-Article in journal (Refereed)
  • 162.
    Dong, Hai
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Thota, Niranjan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Control of the ambident reactivity of the nitrite ion2013In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 11, no 4, p. 648-653Article in journal (Refereed)
    Abstract [en]

    In previous studies, it was reported that a neighbouring equatorial ester group is essential for a good yield of nitrite-mediated triflate inversion, whereas with neighbouring benzyl ether groups or axial ester groups, mixtures are generally produced. In the present study, the origin of this difference was addressed. The ambident reactivity of the nitrite ion has been found to be the cause of the complex product formation observed, which can be controlled by a neighbouring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favoured in its presence. A neighbouring group assistance mechanism is proposed, in addition to steric effects, based on secondary interactions between the neighbouring ester group and the incoming nucleophile. High-level quantum mechanical calculations were carried out in order to delineate this effect. The theoretical results are in excellent agreement with experiments, and suggest a catalytic role for the neighbouring equatorial ester group.

  • 163. Dong, Hai
    et al.
    Zhou, Yixuan
    Pan, Xiaoliang
    Cui, Fengchao
    Liu, Wei
    Liu, Jingyao
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereoelectronic Control in Regioselective Carbohydrate Protection2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 3, p. 1457-1467Article in journal (Refereed)
    Abstract [en]

    Organotin-mediated regioselective protection has been extensively used in organic synthesis for many years. However, the mechanistic origin of the resulting regioselectivity is still not clear. By the comparison of the steric and stereoelectronic effects controlling the geometry of five-membered rings formed from neighboring group participation, from intramolecular acyl group migration, or from orthoester transesterification on pyranoside rings, a theory on the pattern resulting from the reaction with dibutyltin oxide is presented. It is thus suggested that the regioselectivity of organotin-mediated protection is controlled by analogous steric and stereoelectronic effects as in neighboring group participation and acyl group migration, mainly dependent on the stereoelectronic effects of the pyranoside itself, and not related to complex stannylene structures. An organotin protection mechanism is also suggested, emanating from steric and stereoelectronic effects, nucleophilicity, and organotin acyl migration.

  • 164. Dong, J.
    et al.
    Wang, M.
    Li, X.
    Chen, L.
    He, Y.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Simple nickel-based catalyst systems combined with graphitic carbon nitride for stable photocatalytic hydrogen production in water2012In: ChemSusChem, ISSN 1864-5631, Vol. 5, no 11, p. 2133-2138Article in journal (Refereed)
    Abstract [en]

    A molecular catalyst system containing only earth-abundant elements is combined with g-C3N4 as photosensitizer. The in situ generated complexes serve as catalysts for visible-light-driven H2 production in aqueous solution, and do not require organic solvent or a Brønsted acid. H2 evolution from the Ni-based catalyst system can be maintained for over 60 h, demonstrating that the combination is a promising approach to improve the lifetimes of molecular catalysts towards photochemical H2 production.

  • 165. Dong, Jingfeng
    et al.
    Wang, Mei
    Zhang, Pan
    Yang, Songqiu
    Liu, Jianyong
    Li, Xueqiang
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Promoting Effect of Electrostatic Interaction between a Cobalt Catalyst and a Xanthene Dye on Visible-Light-Driven Electron Transfer and Hydrogen Production2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 30, p. 15089-15096Article in journal (Refereed)
    Abstract [en]

    The readily obtained noble-metal-free molecular catalyst systems, with xanthene dyes (Rose Bengal, RB(2-); Eosin Y, EY(2-); and Eosin B, EB(2-)) as photosensitizers, [Co(bpy)(3)]Cl(2) as catalyst, and triethylamine as sacrificial electron donor, are highly active for visible-light-driven (lambda > 450 nm) hydrogen production from water. The turnover frequency is up to 54 TON/min versus RB(2-) with a RB(2-)/[Co(bpy)(3)]Cl(2) molar ratio of 1:10 in CH(3)CN/H(2)O under optimal conditions in the first half hour of irradiation (lambda > 450 rim), and the turnover number is up to 2076 versus RB(2-). Comparative studies show the following: (1) The photocatalytic H(2)-evolving activity of the cationic cobalt complex [Co(bpy)(3)]Cl(2), is apparently higher than the neutral cobaloxime complexes with xanthene dyes as potosensitizers, and also much higher than the analogous system of [Ru(bpy)(3)]Cl(2)/[Co(bpy)(3)]Cl(2). (2) The UV-vis absorptions of xanthene dyes are red shifted to different extents upon addition of [Co(bpy)(3)]Cl(2) to the aqueous or CH(3)CN/H(2)O solutions of these dyes, while no change was observed in UV-vis absorptions of photosensitizer with addition of the cobaloximes to the aqueous solution of RB(2-) or addition of [Co(bpy)(3)]Cl(2) to the aqueous solution of [Ru(bpy)(3)]Cl(2). (3) The fluorescence of RB(2-) is significantly quenched by [Co(bpy)(3)]Cl(2), but not by the cobaloximes. These special performances of [Co(bpy)(3)]Cl(2) are attributed to the electrostatically attractive interaction between the anionic organic dyes and the cationic cobalt catalyst. The probable mechanism for photoinduced hydrogen production catalyzed by the system of RB(2-), [Co(bpy)(3)]Cl(2), and triethylamine is discussed in detail on the basis of fluorescence. fand transient absorption spectroscopic studies. "

  • 166. Dong, Weibing
    et al.
    Wang, Mei
    Liu, Tianbiao
    Liu, Xiaoyang
    Jin, Kun
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Preparation, structures and electrochemical property of phosphine substituted diiron azadithiolates relevant to the active site of Fe-only hydrogenases2007In: Journal of Inorganic Biochemistry, ISSN 0162-0134, E-ISSN 1873-3344, Vol. 101, no 3, p. 506-513Article in journal (Refereed)
    Abstract [en]

    Mono- and di-phosphine diiron azadithiolate complexes [{(mu-SCH2)(2)N(4-NO2C6H4)}Fe-2(CO)(5)(PMe3)] (2), [{(mu-SCH2)(2)N(4NO(2)C(6)H(4))} {Fe(CO)(2)L}(2)] (3, L = PMe3; 4, PMe2Ph) and the mu-hydride diiron complex [3(FeHFe)](+)[PF6](-) were prepared as biontimetic models of the active site of Fe-only hydrogenases. The complexes 2-4 and [3(FeHFe)](+)[PF6](-) were characterized by IR P-31, H-1 and C-13 NMR spectra and their molecular structures were determined by single crystal X-ray analyses. The PMe3 ligand in complex 2 lies on the basal position. The PMe3-disubstituted complex 3 exists as two configuration isomers, transoid basal/basal and apical/basal, in the crystalline state, while two PMe2Ph ligands of 4 are in an apical/basal orientation. The variable temperature P-31 NMR spectra of 2 and 3 were made to have an insight into the existence of the possible conformation isomers of 2 and 3 in solution. The [3(FeHFe)](+) cation possesses the sole transoid ba/ba geometry as other reported mu-hydride diiron analogues. The electrocatalytic property of {(mu-SCH2)(2)NC6H5}[Fe(CO)(2)PMe3](2) (5) was studied for proton reduction in the presence of HOAc.

  • 167. Dressel, Martina
    et al.
    Restorp, Per
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Total synthesis of (+)-alexine by utilizing a highly stereoselective 3+2 annulation reaction of an N-tosyl-alpha-amino aldehyde and a 1,3-bis(silyl)propene2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 10, p. 3072-3077Article in journal (Refereed)
    Abstract [en]

    A novel route towards the polyhydroxylated pyrrolizidine alkaloid (+)-alexine has been developed. A key step in this synthesis is a highly stereoselective [3+2] annulation reaction of N-Ts-alpha-amino aldehyde 7a (Ts=tosyl) and 1,3-bis(silyl)propene 8a for the construction of the polyhydroxylated pyrrolidine subunit of the target molecule. Previous synthetic strategies rely on carbohydrates that require several protecting-group manipulations, thereby making the total number of steps relatively high. The [3+2] annulation strategy compares favorably with carbohydrate-based syntheses and constitutes a highly efficient entry to polyhydroxylated alkaloids.

  • 168.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Artificial Water Splitting: Ruthenium Complexes for Water Oxidation2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns the development and study of Ru-based water oxidation catalysts (WOCs) which are the essential components for solar energy conversion to fuels. The first chapter gives a general introduction about the field of homogenous water oxidation catalysis, including the catalytic mechanisms and the catalytic activities of some selected WOCs as well as the concerns of catalyst design. The second chapter describes a family of mononuclear Ru complexes [Ru(pdc)L3] (H2pdc = 2,6-pyridinedicarboxylic acid; L = pyridyl ligands) towards water oxidation. The negatively charged pdc2 dramatically lowers the oxidation potentials of Ru complexes, accelerates the ligand exchange process and enhances the catalytic activity towards water oxidation. A Ru aqua species [Ru(pdc)L2(OH2)] was proposed as the real catalyst. The third chapter describes the analogues of [Ru(terpy)L3]2+ (terpy = 2,2′:6′,2′′-terpyridine). Through the structural tailor, the ligand effect on the electrochemical and catalytic properties of these Ru complexes was studied. Mechanistic studies suggested that these Ru-N6 complexes were pre-catalysts and the Ru-aqua species were the real WOCs. The forth chapter describes a family of fast WOCs [Ru(bda)L2] (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid). Catalytic mechanisms were thoroughly investigated by electrochemical, kinetic and theoretical studies. The main contributions of this work to the field of water oxidation are (i) the recorded high reaction rate of 469 s−1; (ii) the involvement of seven-coordinate Ru species in the catalytic cycles; (iii) the O-O bond formation pathway via direct coupling of two Ru=O units and (iv) non-covalent effects boosting up the reaction rate. The fifth chapter is about visible light-driven water oxidation using a three component system including a WOC, a photosensitizer and a sacrificial electron acceptor. Light-driven water oxidation was successfully demonstrated using our Ru-based catalysts.

  • 169.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Araujo, Carlos Moyses
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ahlquist, Mårten S. G.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Highly efficient and robust molecular ruthenium catalysts for water oxidation2012In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 109, no 39, p. 15584-15588Article in journal (Refereed)
    Abstract [en]

    Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H-2 driven by solar radiation (H2O + h nu -> 1/2O(2) + H-2). The oxidation of water (H2O -> 1/2O(2) + 2H(+) + 2e(-)) provides protons and electrons for the production of dihydrogen (2H(+) + 2e(-) -> H-2), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes [Ru(bda)L-2] (L = pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze Ce-IV-driven [Ce-IV = Ce(NH4)(2()NO3)(6)] water oxidation with high oxygen production rates up to 286 s(-1) and high turnover numbers up to 55,400.

  • 170.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Bozoglian, Fernando
    Mandal, Sukanta
    Stewart, Beverly
    Privalov, Timofei
    Llobet, Antoni
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II2012In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 4, no 5, p. 418-423Article in journal (Refereed)
    Abstract [en]

    Across chemical disciplines, an interest in developing artificial water splitting to O-2 and H-2, driven by sunlight, has been motivated by the need for practical and environmentally friendly power generation without the consumption of fossil fuels. The central issue in light-driven water splitting is the efficiency of the water oxidation, which in the best-known catalysts falls short of the desired level by approximately two orders of magnitude. Here, we show that it is possible to close that 'two orders of magnitude' gap with a rationally designed molecular catalyst [Ru(bda)(isoq)(2)] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; isoq = isoquinoline). This speeds up the water oxidation to an unprecedentedly high reaction rate with a turnover frequency of >300 s(-1). This value is, for the first time, moderately comparable with the reaction rate of 100-400 s(-1) of the oxygen-evolving complex of photosystem II in vivo.

  • 171.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Isolated Seven-Coordinate Ru(IV) Dimer Complex with HOHOH (-) Bridging Ligand as an Intermediate for Catalytic Water Oxidation2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 30, p. 10397-+Article in journal (Refereed)
    Abstract [en]

    With the inspiration from an oxygen evolving complex (OEC) in Photosystern II (PSII), a mononuclear Ru(II) complex with a tetradentate ligand containing two carboxylate groups has been synthesized and structurally characterized. This Ru(II) complex showed efficient catalytic properties toward water oxidation by the chemical oxidant cerium(IV) ammonium nitrate. During the process of catalytic water oxidation, Ru(III) and Ru(IV) species have been successfully isolated as intermediates. To our surprise, X-ray crystallography together with HR-MS revealed that the Ru(IV) species is a seven-coordinate Ru(IV) dimer complex containing a [HOHOH](-) bridging ligand. This bridging ligand has a short O center dot center dot center dot O distance and is hydrogen bonded to two water molecules. The discovery of this very uncommon seven-coordinate Ru(IV) dimer together with a hydrogen bonding network may contribute to a deeper understanding of the mechanism for catalytic water oxidation. It will also provide new possibilities for the design of more efficient catalysts for water oxidation, which is the key step for solar energy conversion into hydrogen by tight-driven water splitting, the ultimate challenge in artificial photosynthesis.

  • 172.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Mandal, Sukanta
    Bozoglian, Fernando
    Stewart, Beverly
    Privalov, Timofei
    Llobet, Antoni
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    The First Replication of the Water Oxidation Activity of Photosystem-II by a Molecular Ruthenium CatalystManuscript (preprint) (Other academic)
  • 173.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tong, L.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Towards the Visible Light-Driven Water Splitting Device: Ruthenium Water Oxidation Catalysts with Carboxylate-Containing Ligands2014In: Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes, Wiley-Blackwell, 2014, p. 51-76Chapter in book (Other academic)
    Abstract [en]

    The presence of oxo and carboxylate ligands is crucial to decreasing the redox potentials of the oxygen evolving complex (OEC). It has been proved that negatively charged ligands can stabilize the high oxidation states of various transition metal-based complexes and lower their oxidation potentials. This chapter focuses on complexation of transition metals primarily ruthenium (Ru) with carboxylate-containing ligands, in order to develop artificial water oxidation catalysts (WOCs) with small overpotentials. The authors aim at applying highly active and robust WOCs in artificial photosynthesis devices that convert photo energy to chemical energy. A typical visible light-driven water oxidation system consists of three components: a WOC, a photosensitizer, and a sacrificial electron acceptor. The chapter demonstrates a density functional theory (DFT)-directed development of robust Ru-WOCs, showing one of the advantages of molecular WOCs.

  • 174.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tong, Lianpeng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Visible light-driven water oxidation-from molecular catalysts to photoelectrochemical cells2011In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 4, no 9, p. 3296-3313Article in journal (Refereed)
    Abstract [en]

    This perspective article reports the most significant advances in the field of water oxidation-from molecular water oxidation catalysts (WOCs) to photoelectrochemical cells. Different series of catalysts that can be applied in visible light-driven water oxidation catalysis are discussed in details and several key aspects of their catalytic mechanisms are introduced. In order to construct a water oxidation electrode from molecular catalysts, proper immobilization methods have to be employed. Herein, we present one section about how to attach catalysts onto an electrode/material surface. Finally, the state of the art photoelectrochemical cells that achieve visible light-driven water splitting are described.

  • 175.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Inge, A. Ken
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zou, Xiaodong
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Insights into Ru-Based Molecular Water Oxidation Catalysts: Electronic and Noncovalent-Interaction Effects on Their Catalytic Activities2013In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 52, no 14, p. 7844-7852Article in journal (Refereed)
    Abstract [en]

    A series of Ru-bda water oxidation catalysts [Ru(bda)L-2] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; L = [HNEt3][3-SO3-pyridine], 1; 4-(EtOOC)-pyridine, 2; 4-bromopyridine, 3; pyridine, 4; 4-methoxypyridine, 5; 4-(Me2N)-pyridine, 6; 4-[Ph(CH2)(3)]-pyridine, 7) were synthesized with election-donating/-withdrawing groups and hydro-philic/hydrophobic groups in the axial ligands. These complexes were characterized by H-1 NMR spectroscopy, high-resolution mass spectrometry, elemental analysis, and electrochemistry. In addition, complexes 1 and 6 were further identified by single crystal X-ray crystallography, revealing a highly distorted octahedral configuration of the Ru coordination sphere. All of these complexes are highly active toward Ce-IV-driven (Ce-IV = Ce(NH4)(2)(NO3)(6)) water oxidation with oxygen evolution rates up to 119 mols of O-2 per mole of catalyst per second. Their structure-activity relationship was investigated. Electron-withdrawing and noncovalent interactions (attraction) exhibit positive effect on the catalytic activity of Ru-bda catalysts.

  • 176.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Fei
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. State Key Lab of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology (DUT), Dalian, China.
    Highly Efficient Bioinspired Molecular Ru Water Oxidation Catalysts with Negatively Charged Backbone Ligands2015In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 48, no 7, p. 2084-2096Article, review/survey (Refereed)
    Abstract [en]

    The oxygen evolving complex (OEC) of the natural photosynthesis system II (PSII) oxidizes water to produce oxygen and reducing equivalents (protons and electrons). The oxygen released from PSII provides the oxygen source of our atmosphere; the reducing equivalents are used to reduce carbon dioxide to organic products, which support almost all organisms on the Earth planet. The first photosynthetic organisms able to split water were proposed to be cyanobacteria-like ones appearing ca. 2.5 billion years ago. Since then, nature has chosen a sustainable way by using solar energy to develop itself. Inspired by nature, human beings started to mimic the functions of the natural photosynthesis system and proposed the concept of artificial photosynthesis (AP) with the view to creating energy-sustainable societies and reducing the impact on the Earth environments. Water oxidation is a highly energy demanding reaction and essential to produce reducing equivalents for fuel production, and thereby effective water oxidation catalysts (WOCs) are required to catalyze water oxidation and reduce the energy loss. X-ray crystallographic studies on PSII have revealed that the OEC consists of a Mn4CaO5 cluster surrounded by oxygen rich ligands, such as oxyl, oxo, and carboxylate ligands. These negatively charged, oxygen rich ligands strongly stabilize the high valent states of the Mn cluster and play vital roles in effective water oxidation catalysis with low overpotential. This Account describes our endeavors to design effective Ru WOCs with low overpotential, large turnover number, and high turnover frequency by introducing negatively charged ligands, such as carboxylate. Negatively charged ligands stabilized the high valent states of Ru catalysts, as evidenced by the low oxidation potentials. Meanwhile, the oxygen production rates of our Ru catalysts were improved dramatically as well. Thanks to the strong electron donation ability of carboxylate containing ligands, a seven-coordinate Ru-IV species was isolated as a reaction intermediate, shedding light on the reaction mechanisms of Ru-catalyzed water oxidation chemistry. Auxiliary ligands have dramatic effects on the water oxidation catalysis in terms of the reactivity and the reaction mechanism. For instance, Ru-bda (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts catalyze Ce-IV-driven water oxidation extremely fast via the radical coupling of two Ru-V=O species, while Ru-pda (H(2)pda = 1,10-phenanthroline-2,9-dicarboxylic acid) water oxidation catalysts catalyze the same reaction slowly via water nucleophilic attack on a Ru-V-O species. With a number of active Ru catalysts in hands, light driven water oxidation was accomplished using catalysts with low catalytic onset potentials. The structures of molecular catalysts could be readily tailored to introduce additional functional groups, which favors the fabrication of state-of-the-art Ru-based water oxidation devices, such as electrochemical water oxidation anodes and photo-electrochemical anodes. The development of efficient water oxidation catalysts has led to a step forward in the sustainable energy system.

  • 177. Duan, Lele
    et al.
    Wang, Mei
    Li, Ping
    Wang, Ning
    Wang, Fujun
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis, protonation and electrochemical properties of trinuclear NiFe2 complexes Fe-2(CO)(6)(mu(3)-S)(2) Ni(Ph2PCH2)(2)NR (R = n-Bu, Ph) with an internal pendant nitrogen base as a proton relay2009In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 362, no 2, p. 372-376Article in journal (Refereed)
    Abstract [en]

    Two trinuclear NiFe2 complexes Fe-2(CO)(6)(mu(3)-S)(2)[Ni(Ph2PCH2)(2)NR] (R = n-Bu, 1; Ph, 2) containing an internal base were prepared as biomimetic models for the active sites of FeFe and NiFe hydrogenases. Treatment of complex Fe-2(CO)(6)(mu(3)-S)(2)[Ni(Ph2PCH2)(2)N(n-Bu)] (1) with HOTf gave an N-protonated complex [Fe-2(CO)(6)(mu(3)-S)(2){Ni(Ph2PCH2)(2)NH(n-Bu)}][OTf] ([1H][OTf]). The structures of complexes 1, 2 and [1H][OTf] were determined by X-ray crystallography, which shows that the proton held by the N atom of [1H][OTf] lies in an equatorial position. Cyclic voltammograms of complexes 1 and [1H][OTf] were studied and compared with that of Fe-2(CO)(6)(mu(3)-S)(2)[Ni(dppe)].

  • 178.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gorlov, Mikhail
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tong, Lianpeng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Andersson, Samir
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chemical and Photochemical Water Oxidation Catalyzed by Mononuclear Ruthenium Complexes with a Negatively Charged Tridentate Ligand2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 15, p. 4659-4668Article in journal (Refereed)
    Abstract [en]

    Two mononuclear ruthenium complexes [RuL(pic)(3)] (1) and [RuL(bpy)(pic)] (2) (H2L = 2,6-pyridinedicarboxylic acid, pic=4-picoline, bpy = 2,2'-bipyridine) have been synthesized and fully characterized. Both complexes could promote water oxidation chemically and photochemically. Compared with other known ruthenium-based water oxidation catalysts using [Ce(NH4)(2)(NO3)(6)] (Ce-IV) as the oxidant in solution at pH 1.0, complex 1 is one of the most active catalysts yet reported with an initial rate of 0.23 turnovers(-1). Under acidic conditions, the equatorial 4-picoline in complex 1 dissociates first. In addition, ligand exchange in 1 occurs when the Rum state is reached. Based on the above observations and MS measurements of the intermediates during water oxidation by 1 using Ce-IV as oxidant, [RuL(pic)(2)(H2O)](+) is proposed as the real water oxidation catalyst.

  • 179.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tong, Lianpeng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ce-IV- and Light-Driven Water Oxidation by [Ru(terpy)(pic)(3)](2+) Analogues: Catalytic and Mechanistic Studies2011In: CHEMSUSCHEM, ISSN 1864-5631, Vol. 4, no 2, p. 238-244Article in journal (Refereed)
    Abstract [en]

    A series of mononuclear ruthenium polypyridyl complexes [Ru(Mebimpy)(pic)(3)](PF6)(2) (2; Mebimpy=2,6-bis(1-methylbenzimidazol-2-yl)pyridine; pic=4-picoline), Ru(bimpy)(pic)(3) (3; H(2)bimpy=2,6-bis(benzimidazol-2-yl)pyridine), trans-[Ru(terpy)-(pic)(2)Cl](PF6) (4; terpy=2,2';6',2 ''-terpyridine), and trans-[Ru(terpy)(pic)(2)(OH2)](ClO4)(2) (5) are synthesized and characterized as analogues of the known Ru complex, [Ru(terpy)(pic)(3)](PF6)(2) (1). The effect of the ligands on electronic and catalytic properties is studied and discussed. The negatively charged ligand, bimpy(2-), has a remarkable influence on the electrochemical events due to its strong electron-donating ability. The performance in light- and Ce-IV-driven (Ce-IV=Ce(NH4)(2)(NO3)(6)) water oxidation is successfully demonstrated. We propose that ligand exchange between pic and H2O occurs to form the real catalyst, a Ru-aqua complex. The synthesis and testing of trans[Ru(terpy)(pic)(2)(OH2)](ClO4)(2) (5) confirmed our proposal. In addition, complex 5 possesses the best catalytic activity among these five complexes.

  • 180.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Pan
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Wang, Mei
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Visible Light-Driven Water Oxidation by a Molecular Ruthenium Catalyst in Homogeneous System2010In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 49, no 1, p. 209-215Article in journal (Refereed)
    Abstract [en]

    Discovery of an efficient catalyst bearing low overpotential toward water oxidation is a key step for light-driven water splitting into dioxygen and dihydrogen. A mononuclear ruthenium complex, Ru(II)L(pic)(2) (1) (H2L = 2,2'-bipyridine-6,6'-dicarboxylic acids pic = 4-picoline), was found capable of oxidizing water eletrochemically at a relatively low potential and promoting light-driven water oxidation using a three-component system composed of a photosensitizer, sacrificial electron acceptor, and complex 1. The detailed electrochemical properties of 1 were studied, and the onset potentials of the electrochemically catalytic curves in pH 7.0 and pH 1.0 solutions are 1.0 and 1.5 V, respectively. The low catalytic potential of 1 under neutral conditions allows the use of [Ru(bpy)(3)](2+) and even [Ru(dmbpy)(3)](2+) as a photosensitizer for photochemical water oxidation. Two different sacrificial electron acceptors, [Co(NH3)(5)Cl]Cl-2 and Na2S2O8, were used to generate the oxidized state of ruthenium tris(2,2'-bipyridyl) photosensitizers. In addition, a two-hour photolysis of I in a pH TO phosphate buffer did not lead to obvious degradation, indicating the good photostability of our catalyst. However, under conditions of light-driven water oxidation, the catalyst deactivates quickly. In both solution and the solid state under aerobic conditions, complex 1 gradually decomposed via oxidative degradation of its ligands, and two of the decomposed products, sp(3) C-H bond oxidized Ru complexes, were identified. The capability of oxidizing the sp(3) C-H bond implies the presence of a highly oxidizing Ru species, which might also cause the final degradation of the catalyst.

  • 181. Dugassa, Sisay
    et al.
    Lindh, Jenny M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lindsay, Steven W.
    Fillinger, Ulrike
    Field evaluation of two novel sampling devices for collecting wild oviposition site seeking malaria vector mosquitoes: OviART gravid traps and squares of electrocuting nets2016In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 9, article id 272Article in journal (Refereed)
    Abstract [en]

    Background: New sampling tools are needed for collecting exophilic malaria mosquitoes in sub-Saharan Africa to monitor the impact of vector control interventions. The OviART gravid trap and squares of electrocuting nets (e-nets) were recently developed under semi-field conditions for collecting oviposition site seeking Anopheles gambiae (sensu stricto) (s.s.). This study was designed to evaluate the efficacy of these traps for sampling malaria vectors under field conditions. Methods: Prior to field testing, two modifications to the prototype OviART gravid trap were evaluated by (i) increasing the surface area and volume of water in the artificial pond which forms part of the trap, and (ii) increasing the strength of the suction fan. Six sampling tools targeting gravid females (Box gravid trap, detergent-treated ponds, e-nets insect glue-treated ponds, sticky boards and sticky floating-acetate sheets) were compared under field conditions to evaluate their relative catching performance and to select a method for comparison with the OviART gravid trap. Finally, the trapping efficacy of the OviART gravid trap and the square of e-nets were compared with a Box gravid trap during the long rainy season in three household clusters in western Kenya. Results: The OviART gravid trap prototype's catch size was doubled by increasing the pond size [rate ratio (RR) 1.9; 95 % confidence interval (CI) 1.1-3.4] but a stronger fan did not improve the catch. The square of e-nets performed better than the other devices, collecting three times more gravid Anopheles spp. than the Box gravid trap (RR 3.3; 95 % CI 1.4-7.6). The OviART gravid trap collections were comparable to those from the e-nets and 3.3 (95 % CI 1.5-7.0) times higher than the number of An. gambiae senso lato (s.l.) collected by the Box gravid trap. Conclusion: Both OviART gravid trap and squares of e-nets collected wild gravid Anopheles gambiae (s.l.) where natural habitats were within 200-400 m of the trap. Whilst the e-nets are difficult to handle and might therefore only be useful as a research device, the OviART gravid trap presents a promising new surveillance tool. Further field testing is needed in different eco-epidemiological settings to provide recommendations for its use.

  • 182. Dugassa, Sisay
    et al.
    Lindh, Jenny M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Oyieke, Florence
    Mukabana, Wolfgang R.
    Lindsay, Steven W.
    Fillinger, Ulrike
    Development of a Gravid Trap for Collecting Live Malaria Vectors Anopheles gambiae s.l.2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 7, p. e68948-Article in journal (Refereed)
    Abstract [en]

    Background: Effective malaria vector control targeting indoor host-seeking mosquitoes has resulted in fewer vectors entering houses in many areas of sub-Saharan Africa, with the proportion of vectors outdoors becoming more important in the transmission of this disease. This study aimed to develop a gravid trap for the outdoor collection of the malaria vector Anopheles gambiae s.l. based on evaluation and modification of commercially available gravid traps. Methods: Experiments were implemented in an 80 m(2) semi-field system where 200 gravid Anopheles gambiae s.s. were released nightly. The efficacy of the Box, CDC and Frommer updraft gravid traps was compared. The Box gravid trap was tested to determine if the presence of the trap over water and the trap's sound affected catch size. Mosquitoes approaching the treatment were evaluated using electrocuting nets or detergents added to the water in the trap. Based on the results, a new gravid trap (OviART trap) that provided an open, unobstructed oviposition site was developed and evaluated. Results: Box and CDC gravid traps collected similar numbers (relative rate (RR) 0.8, 95% confidence interval (CI) 0.6-1.2; p = 0.284), whereas the Frommer trap caught 70% fewer mosquitoes (RR 0.3, 95% CI 0.2-0.5; p < 0.001). The number of mosquitoes approaching the Box trap was significantly reduced when the trap was positioned over a water-filled basin compared to an open pond (RR 0.7 95% CI 0.6-0.7; p < 0.001). This effect was not due to the sound of the trap. Catch size increased by 60% (RR 1.6, 1.2-2.2; p = 0.001) with the new OviART trap. Conclusion: Gravid An. Gambiae s.s. females were visually deterred by the presence of the trapping device directly over the oviposition medium. Based on these investigations, an effective gravid trap was developed that provides open landing space for egg-laying Anopheles.

  • 183. Dugassa, Sisay
    et al.
    Lindh, Jenny M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Torr, Steve J.
    Lindsay, Steven W.
    Fillinger, Ulrike
    Evaluation of the influence of electric nets on the behaviour of oviposition site seeking Anopheles gambiae s.s2014In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 7, no 1, p. 272-Article in journal (Refereed)
    Abstract [en]

    Background: Electric nets (e-nets) are used to analyse the flight behaviour of insects and have been used extensively to study the host-oriented flight of tsetse flies. Recently we adapted this tool to analyse the oviposition behaviour of gravid malaria vectors, Anopheles gambiae s.s., orienting towards aquatic habitats and traps by surrounding an artificial pond with e-nets and collecting electrocuted mosquitoes on sticky boards on the ground next to the nets. Here we study whether e-nets themselves affect the responses of gravid An. gambiae s.s. Methods: Dual-choice experiments were carried out in 80 m(2) screened semi-field systems where 200 gravid An. gambiae s.s. were released each night for 12 nights per experiment. The numbers of mosquito landing on or approaching an oviposition site were studied by adding detergent to the water in an artificial pond or surrounding the pond with a square of e-nets. We also assessed whether the supporting framework of the nets or the sticky boards used to retain electrocuted mosquitoes influenced the catch. Results: Two similar detergent treated ponds presented in choice tests caught an equal proportion of the mosquitoes released, whereas a pond surrounded by e-nets caught a higher proportion than an open pond (odds ratio (OR) 1.7, 95% confidence interval (CI) 1.1 - 2.7; p < 0.017). The separate evaluation of the impact of the square of electric nets and the yellow boards on the approach of gravid females towards a pond suggests that the tower-like construction of the square of electric nets did not restrict the approach of females but the yellow sticky boards on the ground attract gravid females to a source of water (OR 2.7 95% CI 1.7 - 4.3; p < 0.001). Conclusion: The trapping efficiency of the electric nets is increased when large yellow sticky boards are placed on the ground next to the e-nets to collect electrocuted mosquitoes, possibly because of increased visual contrast to the aquatic habitat. It is therefore important when comparing two treatments that the same trapping device is used in both. The importance of contrast around artificial habitats might be exploited to improve collections of An. gambiae s.s. in gravid traps.

  • 184. Dugassa, Sisay
    et al.
    Lindh, Jenny M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Torr, Steve J.
    Oyieke, Florence
    Lindsay, Steven W.
    Fillinger, Ulrike
    Electric nets and sticky materials for analysing oviposition behaviour of gravid malaria vectors2012In: Malaria Journal, ISSN 1475-2875, E-ISSN 1475-2875, Vol. 11, p. 374-Article in journal (Refereed)
    Abstract [en]

    Background: Little is known about how malaria mosquitoes locate oviposition sites in nature. Such knowledge is important to help devise monitoring and control measures that could be used to target gravid females. This study set out to develop a suite of tools that can be used to study the attraction of gravid Anopheles gambiae s.s. towards visual or olfactory cues associated with aquatic habitats. Methods: Firstly, the study developed and assessed methods for using electrocuting nets to analyse the orientation of gravid females towards an aquatic habitat. Electric nets (1m high x 0.5m wide) were powered by a 12V battery via a spark box. High and low energy settings were compared for mosquito electrocution and a collection device developed to retain electrocuted mosquitoes when falling to the ground. Secondly, a range of sticky materials and a detergent were tested to quantify if and where gravid females land to lay their eggs, by treating the edge of the ponds and the water surface. A randomized complete block design was used for all experiments with 200 mosquitoes released each day. Experiments were conducted in screened semi-field systems using insectary-reared An. gambiae s.s. Data were analysed by generalized estimating equations. Results: An electric net operated at the highest spark box energy of a 400 volt direct current made the net spark, creating a crackling sound, a burst of light and a burning smell. This setting caught 64% less mosquitoes than a net powered by reduced voltage output that could neither be heard nor seen (odds ratio (OR) 0.46; 95% confidence interval (CI) 0.40-0.53, p < 0.001). Three sticky boards (transparent film, glue coated black fly-screen and yellow film) were evaluated as catching devices under electric nets and the transparent and shiny black surfaces were found highly attractive (OR 41.6, 95% CI 19.8 -87.3, p < 0.001 and OR 28.8, 95% CI 14.5 - 56.8, p < 0.001, respectively) for gravid mosquitoes to land on compared to a yellow sticky film board and therefore unsuitable as collection device under the e-nets. With a square of four e-nets around a pond combined with yellow sticky boards on average 33% (95% CI 28-38%) of mosquitoes released were collected. Sticky materials and detergent in the water worked well in collecting mosquitoes when landing on the edge of the pond or on the water surface. Over 80% of collected females were found on the water surface (mean 103, 95% CI 93-115) as compared to the edge of the artificial pond (mean 24, 95% CI 20-28). Conclusion: A square of four e-nets with yellow sticky boards as a collection device can be used for quantifying the numbers of mosquitoes approaching a small oviposition site. Shiny sticky surfaces attract gravid females possibly because they are visually mistaken as aquatic habitats. These materials might be developed further as gravid traps. Anopheles gambiae s.s. primarily land on the water surface for oviposition. This behaviour can be exploited for the development of new trapping and control strategies.

  • 185.
    Duner, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Anderson, Henrik
    Pei, Zhichao
    Ingemarsson, Bjorn
    Aastrup, Teodor
    Ramstrom, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Signal enhancement in ligand-receptor interactions using dynamic polymers at quartz crystal microbalance sensors2016In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 141, no 13, p. 3993-3996Article in journal (Refereed)
    Abstract [en]

    The signal enhancement properties of QCM sensors based on dynamic, biotinylated poly(acrylic acid) brushes has been studied in interaction studies with an anti-biotin Fab fragment. The poly (acrylic acid) sensors showed a dramatic increase in signal response with more than ten times higher signal than the carboxyl-terminated self-assembled monolayer surface.

  • 186.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Anderson, Henrik
    Ingemarsson, Björn
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Determination of Dissociation Constants on Quartz Crystal Microbalance Surfaces by Polymer Signal EnhancementManuscript (preprint) (Other academic)
  • 187.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Anderson, Henrik
    Myrskog, Annica
    Hedlund, Maria
    Aastrup, Teodor
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 14, p. 7559-7564Article in journal (Refereed)
    Abstract [en]

    Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be similar to 220 nm in a collapsed state and similar to 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.

  • 188.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Determination of grafting density of poly(acrylic acid) in a grafting: from approach using quartz crystal microbalance with dissipationManuscript (preprint) (Other academic)
  • 189.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Friction between Surfaces—Polyacrylic Acid Brush and Silica—Mediated by Calcium Ions2010In: Journal of Dispersion Science and Technology, ISSN 0193-2691, E-ISSN 1532-2351, Vol. 31, p. 1285-1287Article in journal (Refereed)
    Abstract [en]

    With this letter, we report how friction can be controlled by inducing physical bonds solely within a polyelectrolyte brush layer, while keeping repulsive interactions between the brush layer and the bare surface that slides above. Our results imply that the nature of the bare surface is of minor importance as long as the repulsive surface interaction is maintained.

  • 190.
    Durieux, Guillaume
    et al.
    CNRS, Ecole Normale Super, Dept Chim.
    Gerdin, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Jutand, Anny
    CNRS, Ecole Normale Super, Dept Chim.
    Rate and Mechanism of the Oxidative Addition of a Silylborane to Pt0 Complexes: Mechanism for the Pt-Catalyzed Silaboration of 1,3-Cyclohexadiene2008In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 27, p. 4236-4241Article in journal (Refereed)
    Abstract [en]

    The chemical reduction of Pt(acac)(2) by DIBALH in the presence of phosphanes, which is used to generate active Pt-0 complexes in the Pt-catalyzed silaboration of cyclohexadiene by 2-(diinethylphenylsilyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1) leading to the 1,4-silaborated product, was mimicked by the electrochemical reduction of Pt(acac)(2) in the presence of 2 equiv. of PR3 (R = Ph, nBu). The electrochemical reduction generates free acac anions and neutral Pt-0-(PR3)(2) complexes. The kinetics of the oxidative addition of bromobenzene (used first as a model molecule) and silylborane 1 to the Pt-0 complexes was investigated and the rate constants determined. Pt-0(PnBu(3))(2) is much more reactive than Pt-0(PPh3)(2) towards 1. From the electrochemical study, it emerges that the acac anions released in the reduction of Pt(acac)(2) do not coordinate to the Pt-0(PR3)(2) complexes. Consequently, the rate of the oxidative addition of 1 to Pt-0(PR3)(2), generated either by the electrochemical reduction or by the chemical reduction by DIBALH, is not affected by the acac anions and a posteriori not by aluminum cations. The oxidative addition and the further step of the catalytic cycle [insertion of the diene into the Pt-B bond of the Si-Pt-B complex generated in the oxidative addition, with formation of the eta(3)-allyl)Pt-Si complex] were monitored by NMR spectroscopy. Pt-0 and Pt-II complexes involved in the catalytic cycle were characterized. The oxidative addition is faster when the ligand is PMe2Ph relative to that obtained with PPh3, in agreement with the electrochemical data. No reductive elimination within the ((eta(3)-allyl))Pt-Si complex is observed when the ligand is PMe2Ph, whereas reactions in the presence of PPh3 proceeded to give the final product. As a consequence, PPh3 is a better ligand than PMe2Ph for the catalytic reaction, as observed experimentally.

  • 191. Edvinsson, Tomas
    et al.
    Li, Chen
    Pschirer, Neil
    Schoeneboom, Jan
    Eickemeyer, Felix
    Sens, Ruediger
    Boschloo, Gerrit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Herrmann, Andreas
    Muellen, Klaus
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Intramolecular charge-transfer tuning of perylenes: Spectroscopic features and performance in Dye-sensitized solar cells2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 42, p. 15137-15140Article in journal (Refereed)
    Abstract [en]

    Five novel perylene molecules with different intramolecular charge-transfer (ICT) characters have been synthesized. The relation between the ICT character for different donating groups and the results for their electro- and photochemical properties as well as their performance in nanostructured dye-sensitized solar cells (nDSC) are reported. With the stronger donors, we obtain a shift of the lowest unoccupied molecular orbital (LUMO) to more negative potential versus normal hydrogen electrode (NHE) as well as an increase the charge separation in the dye upon excitation. Ab initio calculations were used to analyze the effects on orbital energies and electron distribution with the different donors. Incorporating the dyes in nDSCs, we see a drastical improvement in the performance for the more polar dyes. In particular, we find a much improved photovoltage because of higher LUMO levels, allowing conduction band tuning in the TiO2 as well as a contribution from the permanent dipoles in the dyes. The photocurrent improves remarkably with increasing ICT character of the dyes. The external quantum efficiency reached over 70%, and the overall solar-to-electrical energy conversion efficiency was improved to almost 4% for the dye with highest ICT character, which can be compared with devices with the standard N719 dye (Ru(dcbPY)(2)(NCS)(2)) showing 6% under similar conditions. The performance is a significant improvement compared to previous reports for perylenes and lifts the performance from modest to promising. Initial stability tests show that the dye with the highest performance was spectrally stable after more than 2000 h of irradiation in a solar-cell device.

  • 192. Ehrlén, J.
    et al.
    Borg-Karlson, Anna Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kolb, A.
    Selection on plant optical traits and floral scent: Effects via seed development and antagonistic interactions2012In: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 13, no 6, p. 509-515Article in journal (Refereed)
    Abstract [en]

    Evolutionary explanations of plant reproductive traits have usually emphasized optical characteristics of plants and selection mediated by pollinators. In recent years, studies have been broadened by incorporating also interactions with antagonists and by studying plant fragrant cues. Here, we examined if optical and fragrance traits of the perennial herb Primula veris correlated with reproductive success, in terms of fruit and seed set, and with avoidance of seed predators. Selection path analysis showed that both optical and fragrance traits influenced total seed production, and effects occurred both via fruit and seed set and via predator avoidance. In one case the same trait, inflorescence height, influenced total seed production both positively and negatively through effects on different components of fitness. Our results lend support to the notion that selection by mutualists and antagonists simultaneously acts on optical and fragrance traits.

  • 193. Ekstrom, J.
    et al.
    Ott, S.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Akermark, B.
    Eriksson, L.
    Pentacarbonyl(diphenyl(N-propylamine)phosphine)diiron(mu-1,3-propanedithiolate)2005In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 61, p. M852-M853Article in journal (Refereed)
    Abstract [en]

    The title compound, (μ-(SCH2)(2)CH2) Fe(CO)(3)Fe(CO)(2)P( C6H5)(2)NHCH2CH2CH3, has been prepared and characterized as a a model substance for a class of enzymes known as hydrogenases.

  • 194. Ekström, Jesper
    et al.
    Abrahamsson, Maria
    Olson, Carol
    Bergquist, Jonas
    Kaynak, Filiz B.
    Eriksson, Lars
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Becker, Hans-Christian
    Akermark, Bjoern
    Hammarstroem, Leif
    Ott, Sascha
    Bio-inspired, side-on attachment of a ruthenium photosensitizer to an iron hydrogenase active site model2006In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 38, p. 4599-4606Article in journal (Refereed)
    Abstract [en]

    The first ruthenium - diiron complex [(mu- pdt) Fe-2(CO)(5){PPh2(C(6)H(4)CCbpy)} Ru(bpy)(2)](2+) 1 (pdt = propyldithiolate, bpy = 2,2'-bipyridine) is described in which the photoactive ruthenium trisbipyridyl unit is linked to a model of the iron hydrogenase active site by a ligand directly attached to one of the iron centers. Electrochemical and photophysical studies show that the light-induced MLCT excited state of the title complex is localized towards the potential diiron acceptor unit. However, the relatively mild potential required for the reduction of the acetylenic bipyridine together with the easily oxidized diiron portion leads to a reductive quenching of the excited state, instead. This process results in a transiently oxidized diiron unit which may explain the surprisingly high light sensitivity of complex 1.

  • 195.
    El Remaily, Mahmoud Abd El Aleem Ali Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Sohag University, Egypt.
    Naidu, Veluru Ramesh
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ni, Shengjun
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Franzén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Carbocation Catalysis: Oxa-Diels-Alder Reactions of Unactivated Aldehydes and Simple Dienes2015In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 30, p. 6610-6614Article in journal (Refereed)
    Abstract [en]

    The versatility of the trityl cation (TrBF<inf>4</inf>) as a highly efficient Lewis acid organocatalyst is demonstrated in the oxa-Diels-Alder reaction of various unactivated aromatic and aliphatic aldehydes and simple unactivated dienes, such as isoprene and 2,3-dimethylbutadiene. The transformation proceeds smoothly to give 3,6-dihydropyrane adducts in high to moderate yields with catalyst loadings down to 1.0 mol-% under mild reaction conditions. In contrast to most previously reported strategies, this protocol does not require substrate functional group activation, neither by electron-deficient aldehydes (2-oxo aldehydes) or electron-rich dienes (methoxy or amino-butadiene).

  • 196. Ellis, Hanna
    et al.
    Eriksson, Susanna K.
    Feldt, Sandra M.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Lohse, Peter W.
    Lindblad, Rebecka
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Rensmo, Håkan
    Boschloo, Gerrit
    Hagfeldt, Anders
    Linker Unit Modification of Triphenylamine-Based Organic Dyes for Efficient Cobalt Mediated Dye-Sensitized Solar Cells2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 41, p. 21029-21036Article in journal (Refereed)
    Abstract [en]

    Linker unit modification of donor-linker-acceptor-based organic dyes was investigated with respect to the spectral and physicochemical properties of the dyes. The spectral response for a series of triphenylamine (TPA)-based organic dyes, called LEG1-4, was shifted into the red wavelength region, and the extinction coefficient of the dyes was increased by introducing different substituted dithiophene units on the pi-conjugated linker. The photovoltaic performance of dye-sensitized solar cells (DSCs) incorporating the different dyes in combination with cobalt-based electrolytes was found to be dependent on dye binding. The binding morphology of the dyes on the TiO2 was studied using photoelectron spectroscopy, which demonstrated that the introduction of alkyl chains and different substituents on the dithiophene linker unit resulted in a larger tilt angle of the dyes with respect to the normal of the TiO2-surface, and thereby a lower surface coverage. The good photovoltaic performance for cobalt electrolyte-based DSCs found here and by other groups using TPA-based organic dyes with a cyclopentadithiophene linker unit substituted with alkyl chains was mainly attributed to the extended spectral response of the dye, whereas the larger tilt angle of the dye with respect to the TiO2-surface resulted in less efficient packing of the dye molecules and enhanced recombination between electrons in TiO2 and Co(III) species in the electrolyte.

  • 197. El-Sayed, A M
    et al.
    Wainman, L I
    Santangelo, Ellen M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Unelius, C R
    Trimble, R M
    Sex pheromone of a North American population of the spotted tentiform leafminer, Phyllonorycter blancardella2005In: Entomologia Experimentalis et Applicata, ISSN 0013-8703, E-ISSN 1570-7458, Vol. 116, no 2, p. 143-148Article in journal (Refereed)
    Abstract [en]

    The major sex pheromone compound of the spotted tentiform leafminer, Phyllonorycter blancardella (F.) (Lepidoptera: Gracillariidae), from Ontario, Canada, was identified as (10E)-dodecen-1-yl acetate (E10-12:Ac) using chemical analysis and field trapping experiments. The minor compounds (10E)-dodecen-1-ol (E10-12:OH) (4.6%), dodecan-1-ol (12:OH) (2.3%), and (10Z)-dodecen-1-yl acetate (Z10-12:Ac) 1.6% were also identified. The dienic acetate (4E,10E)-dodecadien-1-yl acetate (E4,E10-12:Ac), a compound reported to be attractive to P. blancardella, was not found in the glands of this population. A two-component blend of the major and one of each the three minor compounds, in ratios similar to those found in the sex pheromone gland, did not increase the attractiveness of traps baited with synthetic pheromone. The minor compounds E10-12:OH and 12:OH were not attractive to P. blancardella when tested individually. Z10-12:Ac was attractive to P. blancardella, although traps baited with this compound captured only 2% of the moths that were captured in traps baited with the main compound. A four-component blend of the major and each of the three minor compounds (100 : 1 : 1 : 1) was not more attractive than the major compound alone. The related species Phyllonorycter mespilella was captured in traps baited with E10-12:Ac.

  • 198. El-Seedi, H. R.
    et al.
    El-Barbary, M. A.
    El-Ghorab, D. M. H.
    Bohlin, L.
    Borg-Karlson, Anna-Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Goransson, U.
    Verpoorte, R.
    Recent Insights into the Biosynthesis and Biological Activities of Natural Xanthones2010In: Current Medicinal Chemistry, ISSN 0929-8673, E-ISSN 1875-533X, Vol. 17, no 9, p. 854-901Article in journal (Refereed)
    Abstract [en]

    This review focuses on recent advances in our understanding of the complex biosynthetic pathways and diverse biological activities of naturally occurring xanthones. The biosynthesis section covers studies published from 1989 to 2008 on xanthone production in plants and fungi, while the bioactivity review presents tabulated activities of more than 250 xanthones described in studies published from 2001 to 2008, together with structural information and indications of their wide-ranging potential uses as pharmacological tools. A large number of relevant papers have been published on these subjects (128 cited here), illustrating the diversity of the xanthones and their possible uses.

  • 199. El-Seedi, Hesham R.
    et al.
    El-Shabasy, Rehan
    Sakr, Hanem
    Zayed, Mervat
    El-Said, Asmaa M. A.
    Helmy, Khalid M. H.
    Gaara, Ahmed H. M.
    Turki, Zaki
    Azeem, Muhammad
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ahmed, Ahmed M.
    Boulos, Loutfy
    Borg-Karlson, Anna-Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Göransson, Ulf
    Anti-schistosomiasis triterpene glycoside from the Egyptian medicinal plant Asparagus stipularis2011In: REV BRAS FARMACOGN, ISSN 0102-695X, Vol. 22, no 2, p. 314-318Article in journal (Refereed)
    Abstract [en]

    Bioassay-guided isolation using an in vitro assay testing for anti-schistosomiasis yielded a novel triterpene saponin, asparagalin A, from the n-butanol extract of the roots of Asparagus stipularis Forssk., Asparagaceae. The structure was elucidated by spectroscopic analysis and chemical transformations. Administration of asparagalin A resulted in a retardation of worm growth and locomotion at the first day and showed a significant activity of egg-laying suppression at 200 mu g/mL concentration.

  • 200. El-Seedi, Hesham R.
    et al.
    Khalil, Nasr S.
    Azeem, Muhammad
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Taher, Eman A.
    Goransson, Ulf
    Pålsson, Katinka
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Borg-Karlson, Anna-Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chemical Composition and Repellency of Essential Oils From Four Medicinal Plants Against Ixodes ricinus Nymphs: (Acari Ixodidae)2012In: Journal of medical entomology, ISSN 0022-2585, E-ISSN 1938-2928, Vol. 49, no 5, p. 1067-1075Article in journal (Refereed)
    Abstract [en]

    In our search for effective tick repellents from plant origin, we investigated the effect of essential oils of four medicinal and culinary plants belonging to the family Lamiaceae on nymphs of the tick Ixodes ricinus (L.). The essential oils of the dry leaves of Rosmarinus officinalis (Rosemary) (L.), Mentha spicata (Spearmint) (L.), Origanum majorana (Majoram) (L.), and Ocimum basilicum (Basil) (L.) were isolated by steam distillation and 15 mu g/cm(2) concentration of oils was tested against ticks in a laboratory bioassay. The oils of R. officinalis, M. spicata, and O. majorana showed strong repellency against the ticks 100, 93.2, and 84.3%, respectively, whereas O. basilicum only showed 64.5% repellency. When tested in the field, the oils of R. officinalis and M. spicata showed 68.3 and 59.4% repellency at a concentration of 6.5 mu g/cm(2) on the test cloths. The oils were analyzed by gas chromatography mass spectrometry and the major compounds from the most repellent oils were 1,8-cineole, camphor, linalool, 4-terpineol, borneol, and carvone.

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