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  • 301. Shen, J.
    et al.
    Wang, M.
    Zhang, P.
    Jiang, J.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    Electrocatalytic water oxidation by copper(II) complexes containing a tetra- or pentadentate amine-pyridine ligand2017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 31, p. 4374-4377Article in journal (Refereed)
    Abstract [en]

    Two water soluble copper(ii) complexes containing amine-pyridine ligands were found to be catalytically active for water oxidation reactions in basic solutions, with observed rate constants of 13.1-18.7 s−1. These complexes are robust in basic solutions and displayed good stability over 5 h of electrolysis in pH 11.5 phosphate buffer at 1.4 V vs. NHE.

  • 302. Shen, Z.
    et al.
    Xu, Bo
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hu, Y.
    Yu, Y.
    Ding, H.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hua, J.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Dalian University of Technology (DUT), Dalian, China.
    Tian, H.
    High performance solid-state dye-sensitized solar cells based on organic blue-colored dyes2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 3, p. 1242-1247Article in journal (Refereed)
    Abstract [en]

    The development of novel photosensitizers with very high molar extinction coefficients and broad absorption spectra to enhance the light harvesting efficiency providing high PCEs for solid state dye sensitized solar cells (sDSCs) is a main target for improvement. In this work, two novel organic blue-colored dyes termed S4 and S5 with indeno[1,2-b]thiophene functionalized triphenylamine as the donor, 2,3-diphenylpyrido[3,4-b]pyrazine (PP) or 2,3-diphenylquinoxaline (QT) as the auxiliary acceptor and cyclopentadithiophene (CPDT) as the π-linker were designed and synthesized for sDSCs. S5 containing the QT unit as the electron-withdrawing group exhibits a high molar extinction coefficient of 6.3 × 104 M-1 cm-1 at 600 nm. Most importantly, the S5-based sDSCs shows record PCEs of 7.81% and 8.25% under one sun and 0.5 sun light intensities, respectively, exceeding the PCE of LEG4-based solar cells (7.34%). To the best of our knowledge, this is the first case where an organic blue-colored dye displays a PCE over 7.8% in sDSCs, thus representing record efficiencies for sDSCs. These results clearly show that molecular engineering is a viable way to develop blue-colored dyes with high molar extinction coefficients for use in highly efficient sDSCs. Also, blue-colored dyes open up co-sensitization strategies in combination with traditional organic dyes with yellow-red colours.

  • 303. Shi, Yu
    et al.
    Li, Xiaoyu
    Liu, Jianhui
    Jiang, Wenfeng
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A Suzuki-type cross-coupling reaction of arylacetylene halides with arylboronic acids2011In: Applied organometallic chemistry, ISSN 0268-2605, E-ISSN 1099-0739, Vol. 25, no 7, p. 514-520Article in journal (Refereed)
    Abstract [en]

    A PdCl(2)-catalyzed direct alkynylation of arylboronic acids to give diarylacetylenes is described. The optimal conditions using PdCl(2) as catalyst, MeOH-PhMe-H(2)O as solvent and K(2)CO(3) as base effectively suppressed the formation of homo-coupling product and afforded moderate to good yield of the desired unsymmetrical coupling product. This reaction represents a Suzuki-type sp(2)(C-B)-sp(C-X) cross-coupling.

  • 304. Shi, Yu
    et al.
    Li, Xiaoyu
    Liu, Jianhui
    Jiang, Wenfeng
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    PdCl2-catalyzed cross-coupling reaction of arylacetylene iodides with arylboronic acids to diarylacetylenes2010In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 51, no 28, p. 3626-3628Article in journal (Refereed)
    Abstract [en]

    Anew Suzuki-type cross-coupling reaction between 1-iodo-2-arylalkynes and arylboronic acids to afford a wide variety of functionalized diarylacetylenes in a mild reaction condition was developed. The reaction was catalyzed by a small amount of a structurally simple, commercially available, and stable PdCl2. This unique sp-sp(2) carbon-carbon bond formation provides a new protocol for the synthesis of diarylacetylenes, which is a new addition to the Suzuki cross-coupling reaction. (C) 2010 Elsevier Ltd. All rights reserved.

  • 305. Shifeng, Li
    et al.
    Xichuan, Yang
    Dingfeng, Qu
    Weihan, Wang
    Yu, Wang
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Molecular Design of D-pi-A Type II Organic Sensitizers for Dye Sensitized Solar Cells2012In: Chinese journal of chemistry, ISSN 1001-604X, E-ISSN 1614-7065, Vol. 30, no 10, p. 2315-2321Article in journal (Refereed)
    Abstract [en]

    Four new type II organic dyes with D-pi-A structure (donor-p-conjugated-acceptor) and two typical type II sensitizers based on catechol as reference dyes are synthesized and applied in dye sensitized solar cells (DSCs). The four dyes can be adsorbed on TiO2 through hydroxyl group directly. Electron injection can occur not only through the anchoring group (hydroxyl group) but also through the electron-withdrawing group (?CN) located close to the semiconductor surface. Experimental results show that the type II sensitizers with a D-pi-A system obviously outperform the typical type II sensitizers providing much higher conversion efficiency due to the strong electronic push-pull effect. Among these dyes, LS223 gives the best solar energy conversion efficiency of 3.6%, with Jsc=7.3 mA center dot cm-2, Voc=0.69 V, FF=0.71, the maximum IPCE value reaches 74.9%.

  • 306.
    Song, Xinkai
    et al.
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Yang, Xichuan
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Wang, Haoxin
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    An, Jincheng
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Yu, Ze
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Wang, Xiuna
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Inst Artificial Photosynth, 2 Linggong Rd, Dalian 116024, Peoples R China.
    Improving energy transfer efficiency of dye-sensitized solar cell by fine tuning of dye planarity2019In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 187, p. 274-280Article in journal (Refereed)
    Abstract [en]

    Two push-pull metal-free sensitizers with 5,11-dihydroindolo[3,2-b]carbazole derivatives as electron-donating groups and 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid (BTZ) as electron-withdrawing unit, denoted by SK201 and SK202, were synthesized and used for fabrication of dye-sensitized solar cells (DSSCs). SK202 contains a thienyl group between the donor and acceptor, whereas in SK201 the donor and acceptor are connected directly by a single bond. Introduction of a thienyl group improved the planarity of the dye molecule, broadened the absorption spectrum, enhanced the molar extinction coefficient, increased the dye loading on TiO2, and accelerated interface electron transfer on TiO2. This fine tuning of dye structure improved the performances of DSSCs based on SK202 sensitizers and gave a power conversion efficiency (PCE) of 11.0% (J(SC) 16.5 mA cm(-2), V-OC 932 mV, and fill factor 71.7%), compared with that of 7.2% for SK201, under standard AM1.5G solar irradiation (100 mW cm(-2)) with a Co(II/III) complex based redox couple.

  • 307.
    Staehle, Robert
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Tong, Lianpeng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    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.
    Rau, Sven
    Water oxidation catalyzed by mononuclear ruthenium complexes with a 2,2′-bipyridine-6,6′-dicarboxylate (bda) ligand: How ligand environment influences the catalytic behavior2014In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, no 3, p. 1307-1319Article in journal (Refereed)
    Abstract [en]

    A new water oxidation catalyst [RuIII(bda)(mmi)(OH 2)](CF3SO3) (2, H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid; mmi = 1,3- dimethylimidazolium-2-ylidene) containing an axial N-heterocyclic carbene ligand and one aqua ligand was synthesized and fully characterized. The kinetics of catalytic water oxidation by 2 were measured using stopped-flow technique, and key intermediates in the catalytic cycle were probed by density functional theory calculations. While analogous Ru-bda water oxidation catalysts [Ru(bda)L2] (L = pyridyl ligands) are supposed to catalyze water oxidation through a bimolecular coupling pathway, our study points out that 2, surprisingly, undergoes a single-site water nucleophilic attack (acid-base) pathway. The diversion of catalytic mechanisms is mainly ascribed to the different ligand environments, from nonaqua ligands to an aqua ligand. Findings in this work provide some critical proof for our previous hypothesis about how alternation of ancillary ligands of water oxidation catalysts influences their catalytic efficiency.

  • 308. Sun, Hongfei
    et al.
    Wang, Mei
    Jin, Kun
    Ma, Chengbing
    Zhang, Rong
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Effect of deprotonation of a benzimidazolyl ligand on the redox potential and the structures of mononuclear ruthenium(II) complexes2007In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 26, p. 4128-4131Article in journal (Refereed)
    Abstract [en]

    A monoruthenium(II) complex of the benzimidazolyl ligand and its deprotonated counterpart were prepared and structurally characterized. The reversible protonation/deprotonation process of the ancillary ligand switches the redox potential of the ruthenium(II) core from 0.69 to 0.26 V vs. Ag/AgNO3. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

  • 309. Sun, Hongfei
    et al.
    Wang, Mei
    Li, Fei
    Li, Ping
    Zhao, Zhenbo
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis and structure of a mu-oxo diiron(III) complex with an N-pyridylmethyl-N,N-bis(4-methylbenzimidazol-2-yl)amine ligand and its catalytic property for hydrocarbon oxidation2008In: Applied organometallic chemistry, ISSN 0268-2605, E-ISSN 1099-0739, Vol. 22, no 10, p. 573-576Article in journal (Refereed)
    Abstract [en]

    A mu-oxo diiron(III) complex [{Fe(pbba)Cl}(2)(mu-O)]Cl-2 (1, pbba = N-pyridylmethyl-N,N-bis(4-methylbenzimidazol-2-yl)amine) bearing multi-imidazolyl motifs was synthesized and characterized by X-ray crystallography to closely mimic the structural features of methane monooxygenase. As shown by its X-ray crystal structure, complex 1 is a centrosymmetric dimer with an Fe-O-Fe angle of 180 degrees, and pseudo-octahedral around each iron(III) center. The catalytic ability of title compound in the oxidation of alkane and alkene is investigated by employing tert-butylhydroperoxide and m-chloroperbenzoic acid as oxidants under mild conditions. The catalytic oxidation results showed that radical intermediate dominates the oxidation process.

  • 310.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Dalian University of Technology (DUT), China.
    A closer mimic of the oxygen evolution complex of photosystem II2015In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 348, no 6235, p. 635-636Article in journal (Other academic)
  • 311.
    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.
    Across the Board: Licheng Sun2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 1, p. 22-23Article in journal (Refereed)
    Abstract [en]

    In this series of articles the board members of ChemSusChem discuss recent research articles that they consider of exceptional quality and importance for sustainability. In this entry, Prof. Licheng Sun discusses how solar fuel production (such as water splitting) can be made more efficient and economic on an industrial scale. Recommended is the work by Prof. Xuping Sun, who use non-noble metal-phosphorus-based nanostructures as efficient electrocatalysts for hydrogen generation from water.

  • 312.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China.;KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    PEROVSKITE SOLAR CELLS: Crystal crosslinking2015In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 7, no 9, p. 684-685Article in journal (Other (popular science, discussion, etc.))
  • 313. Sun, Licheng
    et al.
    Fan, X. H.
    Yao, P. J.
    Multi-objective fuzzy optimization algorithm for separation-recycle system2004In: Chinese Journal of Chemical Engineering, ISSN 1004-9541, E-ISSN 2210-321X, Vol. 12, no 2, p. 221-226Article in journal (Refereed)
    Abstract [en]

    Separation-recycle system is an important part in chemical process, and its optimization is a multi-objective problem. In this paper the process optimization procedure is proposed. The fuzzy optimization algorithm with the concept of relative importance degree (RID) is utilized to transfer multi-objective optimization (MO-O) model into a single-objective optimization (SO-O) framework. The treatment of process condensate in synthesis ammonia plant is taken as example to illustrate the optimization procedure, and the satisfactory result demonstrates feasibility and effectiveness of the suggested method.

  • 314.
    Sun, Shiguo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Andersson, Samir
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Rong
    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.
    Unusual partner radical trimer formation in a host complex of cucurbit 8 uril, ruthenium(II) tris-bipyridine linked phenol and methyl viologen2010In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, no 3, p. 463-465Article in journal (Refereed)
    Abstract [en]

    A stable 1 : 1 : 1 inclusion complex of Ru(bpy)(3)-phenol (1), MV2+ and cucurbit[8]uril (CB[8]) is formed in aqueous solution. In the presence of triethanolamine (TEOA), a light-induced formation of unusual partner radical trimer 1-(MV+center dot)(2)-CB[8] has been observed for the first time.

  • 315. Sun, Shiguo
    et al.
    He, Yanxia
    Yang, Zhigang
    Pang, Yi
    Liu, Fengyu
    Fan, Jiangli
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Peng, Xiaojun
    Synthesis and DNA photocleavage study of Ru(bpy)(3)(2+)-(CH2)(n)-MV2+ complexes2010In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 39, no 18, p. 4411-4416Article in journal (Refereed)
    Abstract [en]

    A series of Ru(bpy)(3)(2+)-(CH2)(n)-MV2+ complexes (1, n = 3, 4, 7) used for DNA photocleavage have been designed and synthesized. Under the irradiation of visible light, complexes 1 can cleave supercoiled plasmid DNA (pBR322) both in air and under Ar atmosphere. Radical species such as O2(-center dot), (OH)-O-center dot and the light-induced charge-separated (CS) oxidation state Ru(bpy)(3)(3+)-(CH2)(n)-MV+center dot are responsible for the cleavage. The longer the carbon chain linkage, the higher the DNA photocleavage efficiency. It is noted that backwards intramolecular electron transfer (ET) that exist in complexes 1 can lead to some decreasing effect on the cleavage result, while inclusion of complexes 1 with cucurbit[8]uril (CB[8]) inhibits the backwards ET to some extent, thereby increasing photocleavage efficiency.

  • 316. Sun, Shiguo
    et al.
    Li, Fusheng
    Liu, Fengyu
    Yang, Xue
    Fan, Jiangli
    Song, Fengling
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Peng, Xiaojun
    Synthesis and ECL performance of highly efficient bimetallic ruthenium tris-bipyridyl complexes2012In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, no 40, p. 12434-12438Article in journal (Refereed)
    Abstract [en]

    In order to find the ideal carbon chain linkage number n for achieving the highest ECL in bimetallic ruthenium tris-bipyridyl complexes, a series of novel complexes [(bpy)(2)Ru(bpy')(CH2)(n)(bpy')Ru(bpy)(2)](4+) (1, where bpy is 2,2'-bipyridyl, n = 10, 12, 14) for a coreactant electrochemiluminescence (ECL) system have been synthesized. Their ECL properties at a Au electrode have been studied in 0.1 M phosphate buffer by using tripropylamine (TPrA), 2-(dibutylamino)ethanol (DBAE) and melamine as the coreactant, to compare with that of the previously reported bimetallic ruthenium analogous complex [(bpy)(2)Ru(bpy')(CH2)(8)(bpy')Ru(bpy)(2)](4+). The results demonstrate that the ECL intensity depends largely on the length of the saturated carbon chain linkage number n. The highest ECL is reached when n = 10, suggesting that a synergistic effect on ECL enhancement co-exists between the two intramolecular linked ruthenium activating centers. Density functional theory (DFT) calculation demonstrated that the optimized bond distances between Ru and N(bpy') are the longest both in the ground and the excited triplet states in the case of n = 10, while those for Ru and N(bpy) are the shortest in the excited triplet states. All these factors may be responsible for the above mentioned results. This study provided a methodology to further improve and tune ECL efficiency by using bimetallic ruthenium complexes linked by a flexible saturated carbon chain.

  • 317. Sun, Shiguo
    et al.
    Yang, Yang
    Liu, Fengyu
    Fan, Jiangli
    Kehr, Jan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Peng, Xiaojun
    ECL performance of ruthenium tris-bipyridyl complexes covalently linked with phenothiazine through different bridge2010In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 39, no 37, p. 8626-8630Article in journal (Refereed)
    Abstract [en]

    Three ruthenium complexes 1a, 1b and 1c were synthesized, in which the phenothiazine moiety was covalently linked to the ruthenium complex through a 4 carbon chain and amide bond, respectively. The results demonstrate that one PTZ moiety is preferred to reach a good ECL performance, and the 4 carbon chain linked complex 1a exhibits the highest ECL enhancement (up to about 9 times), in comparison with the commonly utilized parent Ru(bpy)(3)(2+), permitting a lower detection limit of 1.0 x 10(-14) M with signal to noise of 3 for 20 mM DBAE at Au electrode.

  • 318. Sun, Shiguo
    et al.
    Yang, Yang
    Liu, Fengyu
    Fan, Jiangli
    Peng, Xiaojun
    Kehr, Jan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Intra- and intermolecular interaction ECL study of novel ruthenium tris-bipyridyl complexes with different amine reductants2009In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 38, p. 7969-7974Article in journal (Refereed)
    Abstract [en]

    A series of ruthenium(II) tris-bipyridyl complexes covalently linked with different amine reductants such as tripropylamine (TPrA), ethanolamine and diethanolamine for an electrochemiluminescence (ECL) system have been synthesized. Their ECL property at different working electrodes has been studied with and without the presence of TPrA, triethanolamine (TEOA) and 2-(dibutylamino) ethanol (DBAE) as the coreactant, respectively. The results demonstrate that the conjugated ruthenium complex alone can generate ECL through intramolecular interaction at a relatively low concentration, while with intermolecular interaction the ECL intensity increases progressively and becomes increasingly dominant with increasing complex concentration. For the coreactant system ECL, the amine coreactant needed for the conjugate complexes can be significantly lowered in comparison with that of the well known [Ru(bpy)(3)](2+)/TPrA system. One amine substituent is better for the system in order to diminish the steric hindrance, and the intramolecular amine reductant employed should have a similar structure with that of the additive amine coreactant to achieve a good ECL performance, which can pave a new route to further improving the ECL efficiency and increase the sensitivity of detection through combining both intra-and intermolecular interaction.

  • 319. Sun, Shiguo
    et al.
    Yang, Yang
    Liu, Fengyu
    Pang, Yi
    Fan, Jiangli
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Peng, Xiaojun
    Study of Highly Efficient Bimetallic Ruthenium Tris-bipyridyl ECL Labels for Coreactant System2009In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, no 24, p. 10227-10231Article in journal (Refereed)
    Abstract [en]

    A series of bimetallic ruthenium complexes [(bpy)(2)Ru(bpy)(CH2)(n)(bpy)Ru(bpy)(2)](4+) (1, where bpy is 2,2'-bipyridinyl, n = 3, 5, 8) for the coreactant electrochemiluminescence (ECL) system have been synthesized. Their ECL property at different working electrode has been studied in 0.1 M phosphate buffer by using tripropylamine (TPrA) and 2-(dibutylamino) ethanol (DBAE) as the coreactant. The results demonstrate that the ECL intensity depends largely on the length of the saturated carbon chain linkage: the longer is the carbon chain, the higher is the ECL intensity. A remarkable ECL enhancement (up to about 25 times), in comparison with the commonly used metallic [Ru(bpy)(3)](2+), has been observed from 1c (n = 8) at Pt electrode. With 20 mM TPrA, the log of the ECL intensity increases linearly with the log of complex 1c concentrations over the concentration range of 1.0 x 10(-16) to 1.0 x 10(-6) M at glassy carbon electrode. The detection limit is 1.0 x 10(-16) M at a signal-to-noise ratio of 3. This is the highest ECL detection limit for bimetallic system reported until now. The study provides a general methodology to further improve and tune the ECL efficiency by using multimetallic ruthenium complexes.

  • 320.
    Sun, Shiguo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Rong
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Andersson, Samir
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Pan, Jingxi
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Akermark, Bjorn
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    The photoinduced long-lived charge-separated state of Ru(bPY)(3)-methylviologen with cucurbit 8 uril in aqueous solution2006In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 40, p. 4195-4197Article in journal (Refereed)
    Abstract [en]

    A stable 1 : 1 inclusion complex of Ru(bpy)(3)-MV2+ with cucurbit[8]uril (CB[8]) is formed in aqueous solution; upon light irradiation, a long lived (tau similar to 2 mu s) charge-separated state Ru3+- MV+.-CB[8] is observed.

  • 321.
    Sun, Shiguo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Rong
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Andersson, Samir
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Pan, Jingxi
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Zou, Dapeng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Åkermark, Björn
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Host-guest chemistry and light driven molecular lock of Ru(bpy)(3)-viologen with cucurbit 7-8 urils2007In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 111, no 47, p. 13357-13363Article in journal (Refereed)
    Abstract [en]

    Host-guest chemistry and photoinduced electron-transfer processes have been studied in the systems containing Ru(bPy)(3) complex covalently linked to viologen as a guest molecule and cucurbit[n]urils (n = 7, 8) as host molecules in aqueous solution. The Ru(bpy)(3)-viologen complex,[Ru(2,2 '-bipyridine)(2)(4-(4-(1 '-methyl-4,4 '-bipyridinediium-1-yl)butyl)-4 '-methyl-2,2 '-bipyridine)]Cl-4(denoted as RU2+-MV2+, 1) was shown to form stable 1:1 inclusion complexes with cucurbit[7]uril (CB[7]) and cucurbit[8] uril (CB[8]). The binding modes are slightly different with CB[7] and CB[8]. CB[7] preferentially binds to part of the viologen residue in 1 together with the butyl chain, whereas CB[8] preferentially encloses the whole viologen residue. Photoinduced intramolecular electron transfer from the excited-state of the Ru moiety to MV2+ which is inserted into the cavity of the CBs occurred. Long-lived charge-separated states RU3+-MV+center dot, were generated with the lifetimes of 280 ns with CB[7] and 2060 ns with CB[8]. This shows that CBs can slow down the charge recombination within supramolecular systems, and the difference in lifetimes seems to be due to the difference in binding modes. In the presence of a sacrificial electron donor triethanolarnine, light-driven formation of a dimer of MV+center dot inside the CB[8] cavity was observed. This locked molecular dimer can be unlocked by molecular oxygen to give back the original form of the molecular dyad 1 with the MV2+ moiety inserted in the cavity of CB[8]. The processes could be repeated several times and showed nice reversibility.

  • 322. Tan, Qin
    et al.
    Yang, Xichuan
    Cheng, Ming
    Wang, Haoxin
    Wang, Xiuna
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. State Key Laboratory of Fine Chemicals, Dalian, China .
    Application of Small Molecule Donor Materials Based on Phenothiazine Core Unit in Bulk Heterojunction Solar Cells2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 30, p. 16851-16855Article in journal (Refereed)
    Abstract [en]

    A D-pi-A type small molecule PTZ1 and an A-pi-D-pi-A type small molecule PTZ2 with phenothiazine as the central building block and dicyanovinyl as the electron-withdrawing end-group have been designed and synthesized. Compared with D-pi-A type donor material PTZ1, the donor material PTZ2 with A-pi-D-pi-A configuration shows much wider response to solar light. The donor material PTZ1 possesses more positive highest occupied molecular orbital level, and higher V obtained for devices with PTZ1/PC71BM blend as the active layer. An improved efficiency of 3.25% was obtained for the PTZ2/PC71BM based solar cells.

  • 323. Teng, Chao
    et al.
    Yang, Xichuan
    Li, Shifeng
    Cheng, Ming
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Wu, Li-Zhu
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tuning the HOMO Energy Levels of Organic Dyes for Dye-Sensitized Solar Cells Based on Br(-)/Br(3)(-) Electrolytes2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 44, p. 13127-13138Article in journal (Refereed)
    Abstract [en]

    A series of novel metal free organic dyes TC301-TC310 with relatively high HOMO levels were synthesized and applied in dye sensitized solar cells (DSCs) based on electrolytes that contain Br(-)/Br(3)- and I(-)/I(3)(-) The effects of additive Li(+) ions and the HOMO levels of the dyes have an important influence on properties of the dyes and performance of DSCs The addition of Li(+) ions in electrolytes can broaden the absorption spectra of the dyes on TiO(2) films and shift both the LUMO levels of the dyes and the conduction band of TiO(2) thus leading to the increase of J(sc) and the decrease of V(oc) Upon using Br(-)/Br(3)(-) instead of I(-)/I(3)(-), a large increase of V(oc) is attributed to the enlarged energy difference between the redox potentials of electrolyte and the Fermi level of TiO(2), as well as the suppressed electron recombination Incident photon to current efficiency (IPCE) action spectra, electrochemical impedance spectra, and nanosecond laser transient absorption reveal that both the electron collection yields and the dye regeneration yields ((sic)(r)) depend on the potential difference (the driving forces) between the oxidized dyes and the Br(-)/Br(3)(-) redox couple For the dyes for which the HOMO levels are more positive than the redox potential of Br(-)/Br(3)(-) sufficient driving forces lead to the longer effective electron diffusion lengths and almost the same efficient dye regenerations, whereas for the dyes for which the HOMO levels are similar to the redox potential of Br(-)/Br(3)(-), insufficient driving forces lead to shorter effective electron-diffusion lengths and inefficient dye regenerations

  • 324. Teng, Chao
    et al.
    Yang, Xichuan
    Yang, Chao
    Li, Shifeng
    Cheng, Ming
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Molecular Design of Anthracene-Bridged Metal-Free Organic Dyes for Efficient Dye-Sensitized Solar Cells2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 19, p. 9101-9110Article in journal (Refereed)
    Abstract [en]

    A series of metal-free organic dyes bridged by anthracene-containing pi-conjugations were designed and synthesized as new chromophores for the application of dye-sensitized solar cells (DSCs). Detailed investigations on the relationship between the dye structures, photophysical properties, electrochemical properties, and performances of DSCs are described. With the introduction of the anthracene moiety, together with a triple bond for the fine-tuning of molecular planar configurations and to broaden absorption spectra, the short-circuit photocurrent densities (J(sc)) and open-circuit photovoltages (V-oc) of DSCs were improved to a large extent. The improvement of J(sc) is attributed to much broader absorption spectra of the dyes with the anthracene moiety. Electrochemical impedance spectroscopy (EIS) analysis reveals that the introduction of the anthracene moiety suppresses the charge recombination arising from electrons in TiO2 films with I-3(-) ions in the electrolyte, thus improving V-oc considerably. On the basis of optimized molecular structures and DSC test conditions, the dye TC501 shows a prominent solar energy conversion efficiency (eta) up to 7.03% (J(sc) = 12.96 mA . cm(-2), V-OC = 720 mV, ff = 0.753) under simulated AM 1.5 irradiation (100 mW . cm(-2)).

  • 325. Teng, Chao
    et al.
    Yang, Xichuan
    Yang, Chao
    Tian, Haining
    Li, Shifeng
    Wang, Xiuna
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Influence of Triple Bonds as pi-Spacer Units in Metal-Free Organic Dyes for Dye-Sensitized Solar Cells2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 25, p. 11305-11313Article in journal (Refereed)
    Abstract [en]

    Four metal-free organic sensitizers (TC101-TC104) with triple bonds in pi-spacers and five reference dyes (TC, TC105, TPC1, D5, and TH208) without triple bonds were applied in dye-sensitized solar cells to study the influence of triple bonds as pi-spacer units on their photoelectrochemical properties and dye-sensitized solar cells (DSCs) performance. Results show that the introduction of triple bond could red-shift the dye's absorption spectrum due to the enhancement of the pi-spacer. However, the spectrum red-shift is much less than that of the introduction of double bond because of more electronegativity of triple bond. The incident photon-to-current conversion efficiency reveals that the electron transfer yield (Phi(nu)(ET)) of DSCs becomes larger with the introduction of triple bond. Electrochemical impedance spectroscopy analysis reveals that the introduction of triple bond almost does not change the electron lifetimes in TiO2 films but decreases the effective diffusion lengths.

  • 326. Teng, Chao
    et al.
    Yang, Xichuan
    Yuan, Chunze
    Li, Chaoyan
    Chen, Ruikui
    Tian, Haining
    Li, Shifeng
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Two Novel Carbazole Dyes for Dye-Sensitized Solar Cells with Open-Circuit Voltages up to 1 V Based on Br-/Br-3(-) Electrolytes2009In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, no 23, p. 5542-5545Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized solar cells (DSCs) based on two novel carbazole dyes (TC301 and TC306) and a Br-/Br-3(-) redox mediator in dried CH3CN solutions as electrolytes yielded a V-oc of 1.156 V and a eta value of 3.68% and a V-oc of 0.939 V and a eta value of 5.22% under simulated AM 1.5, respectively. The dyes TC301 and TC306 have more positive HOMO levels (1.59 and 1.38 V vs NHE) than the redox potential of Br-/Br-3(-)-based electrolytes, which have sufficient driving force to regenerate dyes. Under similar conditions with an I-/I-3(-) instead of a Br-/Br-3(-) redox mediator, DSCs sensitized by the dyes TC301 and TC306 produced a V-oc of 0.696 V and a eta value of 2.36% and a V-oc of 0.621 V and a eta value of 4.10%, respectively.

  • 327.
    Tian, Haining
    et al.
    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.
    Bora, Ilkay
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Jiang, Xiao
    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.
    Karlsson, Karl Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Hagfeldt, Anders
    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.
    Modifying organic phenoxazine dyes for efficient dye-sensitized solar cells2011In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 21, no 33, p. 12462-12472Article in journal (Refereed)
    Abstract [en]

    Four organic dyes bearing the phenoxazine chromophore have been synthesized and applied in dye-sensitized solar cells (DSCs). The effect of different dye structures on the performance of the DSCs was investigated systematically with photophysical, photovoltaic as well as photoelectrochemical methods. Due to the slow recombination process between injected electrons and electrolyte, the IB3 dye with two 2,4-dibutoxyphenyl units showed the best efficiency of 7.0% under 100 mW cm(-2) light illumination in the liquid state-DSCs. Moreover, the phenoxazine dyes-based solid state-DSCs were fabricated for the first time. With the IB4 dye, a higher efficiency of 3.2% has been achieved under the same light intensity.

  • 328.
    Tian, Haining
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lohse, Peter William
    Vlachopoulos, Nick
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hagfeldt, Anders
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Development of an organic redox couple and organic dyes for aqueous dye-sensitized solar cells2012In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 5, no 12, p. 9752-9755Article in journal (Refereed)
    Abstract [en]

    A water-soluble organic redox couple (TT-/DTT) and new organic dyes (D45 and D51) have been developed for aqueous dye-sensitized solar cells (DSCs). An optimal efficiency of 3.5% was obtained using the D51 dye and an optimized electrolyte composition. The highest IPCE value obtained was 68% at 460 nm.

  • 329.
    Tian, Haining
    et al.
    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.
    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.
    Yu, Ze
    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.
    Hagfeldt, Anders
    Kloo, Lars
    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.
    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.
    A thiolate/disulfide ionic liquid electrolyte for organic dye-sensitized solar cells based on Pt-free counter electrodes2011In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 47, no 36, p. 10124-10126Article in journal (Refereed)
    Abstract [en]

    The ionic liquid, 1-ethyl-3-methylimidazolium tetracyanoborate, was employed to prepare a thiolate/disulfide ionic liquid electrolyte with low viscosity for organic dye-sensitized solar cells (DSCs). CoS was introduced and showed better photovoltaic performance in DSCs than the ubiquitous platinized FTO CE.

  • 330.
    Tian, Haining
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Jiang, Xiao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yu, Ze
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Efficient Organic-Dye-Sensitized Solar Cells Based on an Iodine-Free Electrolyte2010In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, no 40, p. 7328-7331Article in journal (Refereed)
  • 331.
    Tian, Haining
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Oscarsson, Johan
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Eriksson, Susanna K.
    Lindblad, Rebecka
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Hao, Yan
    Boschloo, Gerrit
    Johansson, Erik M. J.
    Gardner, James M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hagfeldt, Anders
    Rensmo, Håkan
    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.
    Enhancement of p-Type Dye-Sensitized Solar Cell Performance by Supramolecular Assembly of Electron Donor and Acceptor2014In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, p. 4282-Article in journal (Refereed)
    Abstract [en]

    Supramolecular interactions based on porphyrin and fullerene derivatives were successfully adopted to improve the photovoltaic performance of p-type dye-sensitized solar cells (DSCs). Photoelectron spectroscopy (PES) measurements suggest a change in binding configuration of ZnTCPP after co-sensitization with C60PPy, which could be ascribed to supramolecular interaction between ZnTCPP and C60PPy. The performance of the ZnTCPP/C60PPy-based p-type DSC has been increased by a factor of 4 in comparison with the DSC with the ZnTCPP alone. At 560 nm, the IPCE value of DSCs based on ZnTCPP/C60PPy was a factor of 10 greater than that generated by ZnTCPP-based DSCs. The influence of different electrolytes on charge extraction and electron lifetime was investigated and showed that the enhanced V-oc from the Co2+/(3+)(dtbp)(3)-based device is due to the positive E-F shift of NiO.

  • 332.
    Tian, Haining
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Soto, Andrea
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hagfeldt, Anders
    Fabregat-Santiago, Francisco
    Mora-Sero, Ivan
    Kang, Yong Soo
    Bisquert, Juan
    Barea, Eva M.
    Effect of the chromophores structures on the performance of solid-state dye sensitized solar cells2014In: Nano, ISSN 1793-2920, Vol. 9, no 5, p. 1440005-Article in journal (Refereed)
    Abstract [en]

    The er effect of metal-free chromophores on dye-sensitized solar cell performance is investigated. Solid state dye-sensitized solar cells (ssDSCs) using dirfferent molecular sensitizers based on tri-phenylamine (TPA) with thiophene linkers and different alkyl chain in the donor unit have been characterized using impedance spectroscopy (IS). We show that different molecular structures play a fundamental role on solar cell performance, by the effect produced on TiO2 conduction band position and in the recombination rate. Dye structure and its electronic properties are the main factors that control the recombination, the capacitance and the efficiency of the cells. A clear trend between the performance of the cell and the optimization level of the blocking effect of the dye structure has been identified in the solid state solar cells with Spiro-OMeTAD hole conductor.

  • 333.
    Tian, Haining
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Iodine-free redox couples for dye-sensitized solar cells2011In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 21, no 29, p. 10592-10601Article in journal (Refereed)
    Abstract [en]

    Redox couples, as one of the crucial components of dye-sensitized solar cells, have been investigated for many years. Due to the many drawbacks of I I(-)/I(3)(-) electrolyte, scientists have paid more attention to seeking other alternative electrolyte systems. Up to now, the best efficiency of iodine-free redox couple-based DSCs, 7.5%, has been achieved by ferrocene/ferrocenium redox couple under AM 1.5G, 100mW cm(-2) light illumination and other redox couples also show the promising future in DSCs. In this feature article, we systematically present three series of iodine-free redox couples including metal-complexes, inorganic and pure organic redox couples, and further compare the different photovoltaic and photophysical properties of these redox couples. As a consequence, the goals of this article are to show the important progress achieved in the redox couples research area of DSCs and analyze the advantages as well as the disadvantages of these redox couples to speed up the further development of iodine-free redox couples in the future.

  • 334. Tian, Haining
    et al.
    Yang, Xichuan
    Chen, Ruikui
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry. 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.
    A metal-free "black dye'' for panchromatic dye-sensitized solar cells2009Article in journal (Refereed)
    Abstract [en]

    A novel metal-free "black dye'' was designed and synthesized for panchromatic dye-sensitized solar cells. Based on this dye, the broader incident photon-to-current conversion efficiency spectrum was obtained over the whole visible range extending into the near-IR region up to 920 nm.

  • 335. Tian, Haining
    et al.
    Yang, Xichuan
    Chen, Ruikui
    Pan, Yuzhen
    Li, Lin
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Phenothiazine derivatives for efficient organic dye-sensitized solar cells2007In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 36, p. 3741-3743Article in journal (Refereed)
    Abstract [en]

    Novel organic dyes based on the phenothiazine (PTZ) chromophore were designed and synthesized for dye-sensitized solar cells, which give solar energy-to-electricity conversion efficiency (eta) of up to 5.5% in comparison with the reference Ru-complex (N3 dye) with an eta value of 6.2% under similar experimental conditions.

  • 336. Tian, Haining
    et al.
    Yang, Xichuan
    Cong, Jiayan
    Chen, Ruikui
    Liu, Jing
    Hao, Yan
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry (closed 20110630). KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Dalian Univ Technol, China.
    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. Dalian Univ Technol, China.
    Tuning of phenoxazine chromophores for efficient organic dye-sensitized solar cells2009In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 41, p. 6288-6290Article in journal (Refereed)
    Abstract [en]

    Through introducing an energy antenna system into a simple phenoxazine dye (TH301), a novel and efficient dye TH305 was designed and synthesized for application in a dye sensitized solar cell with prominent overall conversion efficiency of 7.7%.

  • 337. Tian, Haining
    et al.
    Yang, Xichuan
    Cong, Jiayan
    Chen, Ruikui
    Teng, Chao
    Liu, Jing
    Hao, Yan
    Wang, Lei
    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.
    Effect of different electron donating groups on the performance of dye-sensitized solar cells2010In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 84, no 1, p. 62-68Article in journal (Refereed)
    Abstract [en]

    A series of organic sensitizers containing identical pi-spacers and electron acceptors but different, aromatic amine electron-donating groups, were used in dye-sensitized solar cells to study the effect of the electron donating groups on device performance. The derived photophysical and photovoltaic properties, as well as density functional theory calculations, revealed that the tetrahydroquinoline dye was prone to aggregate upon the surface of titanium dioxide owing to the dye's planar structure. A 45% improvement in efficiency of a tetrahydroquinoline dye based cell was achieved when chenodeoxycholic acid was employed as co-adsorbent. However, the airscrew type of triphenylamine unit and Y type structure of the substituted phenothiazine framework suppressed dye aggregation on titanium dioxide. The efficiency of a phenothiazine dye-based cell fabricated using saturated co-adsorbent in dichloromethane was only 15% greater than that achieved in the absence of co-adsorbent. Electrochemical Impedance Spectroscopy was used to determine the interfacial charge transfer process occurring in solar cells that employed different dyes in both the absence and presence of chenodeoxycholic acid as co-adsorbent.

  • 338. Tian, Haining
    et al.
    Yang, Xichuan
    Pan, Jingxi
    Chen, Ruikui
    Liu, Ming
    Zhang, Qingyu
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A Triphenylamine Dye Model for the Study of Intramolecular Energy Transfer and Charge Transfer in Dye-Sensitized Solar Cells2008In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, no 21, p. 3461-3468Article in journal (Refereed)
    Abstract [en]

    A novel dye (2TPA-R), containing two triphenylamine (TPA) units connected by a vinyl group and rhodanine-3-acetic acid as the electron acceptor, is designed and synthesized successfully to reveal the working principles of organic dye in dye-sensitized solar cells (DSSCs). 2TPA and TPA-R, which consist of two TPA units connected by vinyl and a TPA unit linked with rhodanine-3-acetic acid, respectively, are also synthesized as references to study the intramolecular energy transfer (EnT) and charge transfer (ICT) processes of 2TPA-R in CH2Cl2 solution and on a TiO2 surface. The results suggest that the intramolecular EnT and ICT processes show a positive effect on the performance of DSSCs. However, the flexible structure and less-adsorbed amount of dye on TiO2 may make it difficult to improve the efficiency of DSSCs. This study on intramolecular EnT and ICT processes acts as a guide for the design and synthesis of efficient organic dyes in the future.

  • 339.
    Tian, Haining
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yu, Ze
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Hagfeldt, Anders
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry (closed 20110630).
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Organic Redox Couples and Organic Counter Electrode for Efficient Organic Dye-Sensitized Solar Cells2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 24, p. 9413-9422Article in journal (Refereed)
    Abstract [en]

    A series of organic thiolate/disulfide redox couples have been synthesized and have been studied systematically in dye-sensitized solar cells (DSCs) on the basis of an organic dye (TH305). Photophysical, photoelectrochemical, and photovoltaic measurements were performed in order to get insights into the effects of different redox couples on the performance of DSCs. The polymeric, organic poly(3,4-ethylenedioxythiophene) (PEDOT) material has also been introduced as counter electrode in this kind of noniodine-containing DSCs showing a promising conversion efficiency of 6.0% under AM 1.5G, 100 mW.cm(-2) light illumination. Detailed studies using electrochemical impedance spectroscopy and linear-sweep voltammetry reveal that the reduction of disulfide species is more efficient on the PEDOT counter electrode surface than on the commonly used platinized conducting glass electrode. Both pure and solvated ionic-liquid electrolytes based on a thiolate anion have been studied in the DSCs. The pure and solvated ionic-liquid-based electrolytes containing an organic redox couple render efficiencies of 3.4% and 1.2% under 10 mW.cm(-2) light illumination, respectively.

  • 340. Tian, Jie
    et al.
    Yang, Xichuan
    Zhao, Jianghua
    Wang, Lei
    Wang, Weihan
    Li, Jiajia
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian Univ Technol, Peoples R China.
    Organic D-pi-A sensitizer with pyridinium as the acceptor group for dye-sensitized solar cells2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 65, p. 34644-34648Article in journal (Refereed)
    Abstract [en]

    Two metal-free organic dyes with triphenylamide (TPA) as the donor group and pyridinium (m-carboxyl-N-methylpyridinium and N-methylcarboxylpyridinium) as the acceptor and anchoring group have been synthesized for dye-sensitized solar cells (DSSCs). A systematic investigation of the relationship between the structures and physical, electrochemical and photovoltaic properties has been conducted. The devices sensitized by TJ101 which employed m-carboxyl-N-methylpyridinium as the acceptor group has achieved a conversion efficiency of 5.4% (J(sc) = 10.8 mA cm(-2), V-oc = 680 mV, FF = 74.2%) under AM 1.5 irradiation. In contrast, much lower efficiency of 4.0% was obtained when a reference dye TJ101R with m-carboxylpyridine as the acceptor group was employed as a sensitizer.

  • 341.
    Tong, Lianpeng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Privalov, Timofei
    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.
    Structural Modifications of Mononuclear Ruthenium Complexes: A Combined Experimental and Theoretical Study on the Kinetics of Ruthenium-Catalyzed Water Oxidation2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 2, p. 445-449Article in journal (Refereed)
    Abstract [en]

    Small change, big difference: A minor structural modification of water-oxidation catalysts changes the kinetics of O2 evolution from second- to first-order (see scheme). According to DFT calculations, the torsional flexibility of the chelating ligands and their reorganization through the catalytic cycle are implicated in pathway selectivity, and the auxiliary carboxylate group becomes involved in proton-coupled nucleophilic attack.

  • 342.
    Tong, Lianpeng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Götelid, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Oxygen evolution at functionalized carbon surfaces: A strategy for immobilization of molecular water oxidation catalysts2012In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 48, no 80, p. 10025-10027Article in journal (Refereed)
    Abstract [en]

    A molecular Ru(ii) water oxidation catalyst was immobilized on a conductive carbon surface through a covalent bond, and its activity was maintained at the same time. The method can be applied to other materials and may inspire development of artificial photosynthesis devices.

  • 343.
    Tong, Lianpeng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Inge, A. Ken
    Stockholm University.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zou, Xiaodong
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Catalytic Water Oxidation by Mononuclear Ru Complexes with an Anionic Ancillary Ligand2013In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 52, no 5, p. 2505-2518Article in journal (Refereed)
    Abstract [en]

    Mononuclear Ru-based water oxidation catalysts containing anionic ancillary ligands have shown promising catalytic efficiency and intriguing properties. However, their insolubility in water restricts a detailed mechanism investigation. In order to overcome this disadvantage, complexes [Ru-II(bpc)(bpy)OH2](+) (1(+), bpc = 2,2'-bipyridine-6-carboxylate, bpy = 2,2'-bipyridine) and [Ru-II(bpc)(pic)(3)](+) (2(+), pic = 4-picoline) were prepared and fully characterized, which features an anionic tridentate ligand and has enough solubility for spectroscopic study in water. Using Ce-IV as an electron acceptor, both complexes are able to catalyze O-2-evolving reaction with an impressive rate constant. On the basis of the electrochemical and kinetic studies, a water nucleophilic attack pathway was proposed as the dominant catalytic cycle of the catalytic water oxidation by 1(+), within which several intermediates were detected by MS. Meanwhile, an auxiliary pathway that is related to the concentration of Ce-IV was also revealed. The effect of anionic ligand regarding catalytic water oxidation was discussed explicitly in comparison with previously reported mononuclear Ru catalysts carrying neutral tridentate ligands, for example, 2,2':6',2 ''-terpyridine (tpy). When 2(+) was oxidized to the trivalent state, one of its picoline ligands dissociated from the Ru center. The rate constant of picoline dissociation was evaluated from time-resolved UV-vis spectra.

  • 344.
    Tong, Lianpeng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wang, Ying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Duan, Lele
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Xu, Yunhua
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Cheng, Xiao
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    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.
    Water Oxidation Catalysis: Influence of Anionic Ligands upon the Redox Properties and Catalytic Performance of Mononuclear Ruthenium Complexes2012In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 51, no 6, p. 3388-3398Article in journal (Refereed)
    Abstract [en]

    Aiming at highly efficient molecular catalyts for water oxidation, a mononuclear ruthenium complex Ru-II(hqc)(pic)(3) (1; H(2)hqc = 8-hydroxyquinoline-2-carboxylic acid and plc = 4-picoline) containing negatively charged carboxylate and phenolate donor groups has been designed and synthesized. As a comparison, two reference complexes, Ru-II(pdc)(pic)(3) (2; H(2)pdc = 2,6-pyridine-dicarboxylic acid) and Ru-II(tpy)(pic)(3) (3; tpy = 2,2':6',2 ''-terpyridine), have also been prepared. All three complexes are fully characterized by NMR, mass spectrometry (MS), and X-ray crystallography. Complex 1 showed a high efficiency toward catalytic water oxidation either driven by chemical oxidant (Ce-IV in a pH 1 solution) with a initial turnover number of 0.32 s(-1), which is several orders of magnitude higher than that of related mononuclear ruthenium catalysts reported in the literature, or driven by visible light in a three-component system with [Ru(bpy)(3)](2+) types of photosensitizers. Electrospray ionization MS results revealed that at the Rum state complex 1 undergoes ligand exchange of 4-picoline with water, forming the authentic water oxidation catalyst in situ. Density functional theory (DFT) was ernployed to explain how anionic ligands (hqc and pdc) facilitate the 4-picoline dissociation compared with a neutral ligand (tpy). Electrochemical measurements show that complex 1 has a much lower E(Ru-III/Ru-II) than that of reference complex 2 because of the introduction of a phenolate ligand. DFT was further used to study the influence of anionic ligands upon the redox properties of mononuclear aquaruthenium species, which are postulated to be involved in the catalysis cycle of water oxidation.

  • 345. Tran, Lien-Hoa
    et al.
    Eriksson, Lars
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Akermark, Bjorn
    A new square planar mononuclear Mn-III complex for catalytic epoxidation of stilbene2008In: Journal of Organometallic Chemistry, ISSN 0022-328X, E-ISSN 1872-8561, Vol. 693, no 6, p. 1150-1153Article in journal (Refereed)
    Abstract [en]

    The manganese(III) complex (2) with a diamide ligand has been synthesized. This complex was found to catalyze both the epoxidation of (Z)- and (E)-stilbene with high conversion and the oxidation of benzyl alcohol to benzaldehyde.

  • 346. Troppmann, Stefan
    et al.
    Brandes, Eva
    Motschmann, Hubert
    Li, Fei
    Wang, Mei
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian Univ Technol, China.
    Koenig, Burkhard
    Enhanced Photocatalytic Hydrogen Production by Adsorption of an [FeFe]-Hydrogenase Subunit Mimic on Self-Assembled Membranes2016In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 4, p. 554-560Article in journal (Refereed)
    Abstract [en]

    Self-assembled vesicles with membrane-embedded or adsorbed ruthenium polypyridine complexes were further functionalized by the adsorption of an [FeFe]-hydrogenase subunit mimic to the membrane interface enhancing the photocatalytic hydrogen production in water under acidic conditions. The resulting two-dimensional membrane assembly places the photosensitizer and hydrogen-evolving diiron complex in close proximity resulting in a six-to twelvefold increase in the turnover number as compared to the same system in the absence of lipid membranes. The interface assembly then enables the combining of hydrophilic and hydrophobic catalytic entities for light-driven proton reduction in acidic water and provides a flexible method for membrane functionalization.

  • 347. Wang, Dongping
    et al.
    Wang, Mei
    Wang, Xiuna
    Zhang, Rong
    Ma, Jia
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Influence of the built-in pyridinium salt on asymmetric epoxidation of substituted chromenes catalysed by chiral (pyrrolidine salen)Mn(III) complexes2007In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 270, no 02-jan, p. 278-283Article in journal (Refereed)
    Abstract [en]

    Chiral (pyrrolidine salen)Mn(III) complexes 1 with an N-benzoyl group and 2 with an N-isonicotinoyl group as well as the corresponding N-methyl (3) and N-benzyl (4) pyridinium salts of 2 were synthesized. The catalytic properties of 1-4 and 2 with excess CH3I were explored to figure out the influence of the internal pyridinium salt in the catalyst on asymmetric epoxidation of substituted chromenes with NaClO/PPNO as an oxidant system in the aqueous/organic biphasic medium. The (pyrrolidine salen)Mn(III) complexes with an internal pyridinium salt, either formed in situ or isolated, displayed higher activities than analogous complexes 1, 2 and Jacobsen's catalyst in the aforementioned reaction, with comparable high yields and ee values. The acceleration of the reaction rate is attributed to the phase transfer capability of the built-in pyridinium salt of the (salen)Mn(III) catalyst. The effect of the internal pyridinium salt on the epoxidation of substituted chromenes is similar to that of the external pyridinium salts and ammonium halides.

  • 348. Wang, Dongping
    et al.
    Wang, Mei
    Zhang, Rong
    Wang, Xiuna
    Gao, Aiping
    Ma, Jia
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Asymmetric epoxidation of styrene and chromenes catalysed by dimeric chiral (pyrrolidine salen)Mn(III) complexes2006In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 315, p. 120-127Article in journal (Refereed)
    Abstract [en]

    Two dimeric chiral (pyrrolidine salen)Mn(III) complexes 3 and 4 were prepared, in which the two (pyrrolidine salen)Mn(III) units are linked either by a p-xylylene or by ap-phthalyl bridge. High yields were attained for asymmetric epoxidation of styrene and substituted chromenes at 0.5-4.0 mol% catalyst loading of 3 and 4 using NaClO/PPNO and m-CPBA/NMO as oxidant systems, with 37-39% ee for styrene and 86-95% ee for substituted chromenes. Dimeric complexes 3 and 4 displayed higher activities than their parent monomeric complexes 1 and 2 of double equiv for epoxidation of substituted chromenes. Complex 3 bearing two tertiary amine units displayed considerably higher activity than analogous dimeric complex 4 containing two carboxamide units in the aforementioned reaction. The effect of excess CH3I on the epoxidation of 6-nitro-2,2-dimethylchromene catalysed by 3 in the aqueous/organic biphasic medium was explored. The recovery and recycling possibilities of the dimeric complexes 3 and 4 were studied.

  • 349. Wang, F. J.
    et al.
    Wang, M.
    Liu, X. Y.
    Jin, K.
    Dong, W. B.
    Li, G. H.
    Åkermark, B.
    Sun, Licheng C.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology, China.
    Spectroscopic and crystallographic evidence for the N-protonated (FeFeI)-Fe-I azadithiolate complex related to the active site of Fe-only hydrogenases2005In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 25, p. 3221-3223Article in journal (Refereed)
    Abstract [en]

    The complex [{(mu-SCH2)(2)N(CH2C6H4-2-Br)}Fe-2(CO)(6)] and its N-protonated species, as structural models of the Fe-only hydrogenase active site, were identified spectroscopically and crystallographically, and their molecular structures show the 0.04 - 0.1 angstrom lengthening of the three N-C bonds and an intramolecular H center dot center dot center dot Br contact (2.82 angstrom) in the crystalline state of the N-protonated species.

  • 350. Wang, Fujun
    et al.
    Wang, Mei
    Liu, Xiaoyang
    Jin, Kun
    Donga, Weibing
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Protonation, electrochemical properties and molecular structures of halogen-functionalized diiron azadithiolate complexes related to the active site of iron-only hydrogenases2007In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 34, p. 3812-3819Article in journal (Refereed)
    Abstract [en]

    Diiron complexes [{( mu-SCH2) 2NCH(2)C(6)H(4)X}{Fe( CO)(2)L}(2)] ( L = CO, X = 2-Br, 1; 2-F, 2; 3-Br, 3; L = PMe3, X = 2-Br, 4) were prepared as biomimetic models of the iron-only hydrogenase active site. The N-protonated species [ 1( NH)]+ClO4-, [ 2( NH)]+ClO4- and the mu-hydride diiron complex [ 4( FeHFe)]+PF6- were obtained in the presence of proton acids and well characterized. The protonation process of 4 was studied by in-situ IR and NMR spectroscopy, which suggests the formation of the diprotonated species [ 4( NH)( FeHFe)](2+) in the presence of an excess of proton acid. The molecular structures of 1, [ 1( NH)]+ClO4-, 4 and [ 4( FeHFe)]+PF6- were determined by X-ray crystallography. The single-crystal X-ray analysis reveals that an intramolecular H center dot center dot center dot Br contact ( 2.82 angstrom) in the crystalline state of [ 1( NH)]+ClO4-. In the presence of 1-6 equiv of the stronger acid HOTf, complex 1 is readily protonated on the bridged-N atom and can electrochemically catalyze the proton reduction at a relatively mild potential ( ca. -1.0 V). Complex 4 is also electrocatalytic active at -1.4 V in the presence of HOTf with formation of the mu-hydride diiron species.

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