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Karaush, N. N., Baryshnikov, G. V., Ågren, H. & Minaev, B. F. (2018). A theoretical study of new representatives of closed- and open-circle benzofuran and benzocyclopentadienone oligomers. New Journal of Chemistry, 42(14), 11493-11505
Open this publication in new window or tab >>A theoretical study of new representatives of closed- and open-circle benzofuran and benzocyclopentadienone oligomers
2018 (English)In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 42, no 14, p. 11493-11505Article in journal (Refereed) Published
Abstract [en]

Owing to their potential use as materials for strong optical rotation, circular dichroism and circularly polarized luminescence, the structure and energetic stability of novel closed- and open-circle benzofuran and benzocyclopentadienone oligomers have been studied computationally using the DFT method. It is found that an extension of the macrocycle size (n = 10-30) for the closed-circle species leads to a gradual transformation of their structure from saddle- to helical- and then to a wing-like shape. At the same time, the smaller closed-circle representatives with n = 4 and 6 exhibit a bowl-shaped structure due to the high energy strain of their molecular structures. Application of the NICS (nucleus-independent chemical shift) criterion to the here studied open-circle benzofuran and benzocyclopentadienone species with planar linear, planar fan-shape and helical molecular topology indicates that for the planar benzofuran series the inner benzene ring is more aromatic than the outer hexagons, while the aromaticity of the outer and inner furan rings is insensitive to the molecular size variations. The replacement of the aromatic furan rings by antiaromatic cyclopentadienone fragments for the planar linear species leads to a decrease of aromaticity of the benzene rings from the edge to the center of the benzocyclopentadienone chain. On the other hand, for the planar fan-shape benzocyclopentadienone series a zigzag trend in the NICS values is observed for the benzene rings. Loss of planarity only slightly affects the aromaticity of the helical open-circle benzofuran and benzocyclopentadienone oligomers. We propose that an increase of the NICS indices for the outer and inner rings of the macromolecular helical species is due to the magnetic couplings between the superimposed benzene and furan/cyclopentadienone rings.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-232758 (URN)10.1039/c8nj00601f (DOI)000438394800034 ()2-s2.0-85049737696 (Scopus ID)
Funder
Swedish National Infrastructure for Computing (SNIC)Carl Tryggers foundation , CTS 17:514
Note

QC 20180803

Available from: 2018-08-03 Created: 2018-08-03 Last updated: 2018-08-03Bibliographically approved
Zhou, Y., Baryshnikov, G. V., Li, X., Zhu, M., Ågren, H. & Zhu, L. (2018). Anti-Kasha's Rule Emissive Switching Induced by Intermolecular H-Bonding. Chemistry of Materials, 30(21), 8008-8016
Open this publication in new window or tab >>Anti-Kasha's Rule Emissive Switching Induced by Intermolecular H-Bonding
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2018 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 21, p. 8008-8016Article in journal (Refereed) Published
Abstract [en]

The exploration of emission pathways from high-excited states in organic luminogens has recently become prosperous owing to improved possibilities to study so-called anti-Kasha's rule emission with the potential of improving the luminescent quantum efficiency. However, emission pathway switching among different high-excited states has rarely been addressed through external control. We here present a rational design and synthesis of a novel azulene-based emitter to achieve a responsive control of its anti-Kasha's rule emissive switching. The emitter initially gives rise to an S-3-to-S-0 dominant emission as indicated by our experimental and theoretical studies. On this basis, it can be toggled into an S-2-to-S-0 dominant emission upon the H-bond formation between the triformyl groups and water molecules. Such a process, which originates from the H-bonding regulated distribution of excited state energy, is accompanied by a remarkable fluorescent color conversion and a significant improvement of the fluorescent quantum yield in the azulene family. Moreover, a reversible emissive switching in doped films was observed to depend on a solid-state H-bond tuning process with moisture sensitivity. These results may provide new insight for building advanced chemical systems for visualized sensing with high distinguishability.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-240002 (URN)10.1021/acs.chemmater.8b03699 (DOI)000450696100068 ()2-s2.0-85055633460 (Scopus ID)
Funder
Carl Tryggers foundation , CTS 16:536 17:514
Note

QC 20181210

Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2018-12-10Bibliographically approved
Natarajan Arul, M., Nordberg, A. & Ågren, H. (2018). Different Positron Emission Tomography Tau Tracers Bind to Multiple Binding Sites on the Tau Fibril: Insight from Computational Modeling. ACS Chemical Neuroscience, 9(7), 1757-1767
Open this publication in new window or tab >>Different Positron Emission Tomography Tau Tracers Bind to Multiple Binding Sites on the Tau Fibril: Insight from Computational Modeling
2018 (English)In: ACS Chemical Neuroscience, ISSN 1948-7193, E-ISSN 1948-7193, Vol. 9, no 7, p. 1757-1767Article in journal (Refereed) Published
Abstract [en]

Using the recently reported cryo-EM structure for the tau fibril [Fitzpatrick et al. (2017) Nature 547, 185-190], which is a potential target concerning Alzheimer's disease, we present the first molecular modeling studies on its interaction with various positron emission tomography (PET) tracers. Experimentally, based on the binding assay studies, at least three different high affinity binding sites have been reported for tracers in the tau fibril. Herein, through integrated modeling using molecular docking, molecular dynamics, and binding free energy calculations, we provide insight into the binding patterns of various tracers to the tau fibril. We suggest that there are four different high affinity binding sites available for many of the studied tracers showing varying binding affinity to different binding sites. Thus, PBB3 binds most strongly to site 4, and interestingly, this site is not a preferable site for any other tracers. For THIC5351, our data show that it strongly binds to sites 3 and 1, the former one being more preferable. We also find that MK6240 and T807 bind to site 1 specifically. The modeling data also give some insight into whether a tracer bound to a specific site can be replaced by others or not. For example, the displacement of T807 by PBB3 as reported experimentally can also be explained and attributed to the larger binding affinity of the latter compound in all binding sites. The binding free energy results explain very well the small binding affinity of THK523 compared to all the aryl quinoline moieties containing THK tracers. The ability of certain tau tracers, like FDDNP and THK523, to bind to amyloid fibrils has also been investigated. Furthermore, such off-target interaction of tau tracers with amyloid beta fibrils has been validated using a quantum mechanical fragmentation approach.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-232912 (URN)10.1021/acschemneuro.8b00093 (DOI)000439531400024 ()29630333 (PubMedID)2-s2.0-85050285842 (Scopus ID)
Note

QC 20180808

Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2018-11-13Bibliographically approved
Mudedla, S. K., Natarajan Arul, M. & Ågren, H. (2018). Free Energy Landscape for Alpha-Helix to Beta-Sheet Interconversion in Small Amyloid Forming Peptide under Nanoconfinement. Journal of Physical Chemistry B, 122(42), 9654-9664
Open this publication in new window or tab >>Free Energy Landscape for Alpha-Helix to Beta-Sheet Interconversion in Small Amyloid Forming Peptide under Nanoconfinement
2018 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 122, no 42, p. 9654-9664Article in journal (Refereed) Published
Abstract [en]

Understanding the mechanism of fibrillization of amyloid forming peptides could be useful for the development of therapeutics for Alzheimer's disease (AD). Taking this standpoint, we have explored in this work the free energy profile for the interconversion of monomeric and dimeric forms of amyloid forming peptides into different secondary structures namely beta-sheet, helix, and random coil in aqueous solution using umbrella sampling simulations and density functional theory calculations. We show that the helical structures of amyloid peptides can form beta sheet rich aggregates through random coil conformations in aqueous condition. Recent experiments (Chem. Eur. J. 2018, 24, 3397-3402 and ACS Appl. Mater. Interfaces 2017, 9, 21116-21123) show that molybdenum disulfide nanosurface and nanoparticles can reduce the fibrillization process of amyloid beta peptides. We have unravelled the free energy profile for the interconversion of helical forms of amyloid forming peptides into beta-sheet and random coil in the presence of a two-dimensional nanosurface of MoS2. Results indicate that the monomer and dimeric forms of the peptides adopt the random coil conformation in the presence of MoS2 while the helical form is preferable for the monomeric form and that the beta-sheet and helix forms are the preferable forms for dimers in aqueous solution. This is due to strong interaction with MoS2 and intramolecular hydrogen bonds of random coil conformation. The stabilization of random coil conformation does not lead to a beta sheet like secondary structure for the aggregate. Thus, the confinement of MoS2 promotes deaggregation of amyloid beta peptides rather than aggregation, something that could be useful for the development of therapeutics for AD.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-239093 (URN)10.1021/acs.jpcb.8b07917 (DOI)000448753800004 ()30253649 (PubMedID)2-s2.0-8505500840 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , SNIC2017-12-49Swedish Foundation for Strategic Research , SNIC2018-3-3
Note

QC 20181121

Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2018-11-21Bibliographically approved
Karaush, N. N., Minaeva, V. A., Baryshnikov, G. V., Minaev, B. F. & Ågren, H. (2018). Identification of tautomeric intermediates of a novel thiazolylazonaphthol dye - A density functional theory study. Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, 203, 324-332
Open this publication in new window or tab >>Identification of tautomeric intermediates of a novel thiazolylazonaphthol dye - A density functional theory study
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2018 (English)In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 203, p. 324-332Article in journal (Refereed) Published
Abstract [en]

The recently synthesized thiazolylazo dye, 1-(5-benzy1-1,3-thiazol-2-yl)diazenyllnaphthalene-2-ol called shortly BnTAN, is studied by density functional theory (DFT) in three tautomeric forms in order to explain the available H-1 NMR, UV-Vis and FTIR spectra. An experimentally observed IR band at 1678 cm(-1), assigned to the C=O bond stretching vibration, supports the notion that BnTAN retains in the less stable keto-form even in the solid state due to an ultrafast single-coordinate intramolecular proton transfer. This finding is also in a good agreement with an X-ray crystallography analysis which indicates an intermediate position of the proton between the OH and -N=N-groups. Calculations also show that some experimentally observed H-I NMR signals could be considered as being averaged values between theoretically calculated chemical shifts for the corresponding protons in the keto- and enol-tautomers. At the same time the UV-Vis spectra are almost insensitive to the tautomerization processes as the main single band absorption at 500 nm is present in all tautomers according to our TD DFT simulations. The minor differences in spectral features of the long-wavelength visible region are also noted and discussed with respect to the manifestation of the less stable tautomer form.

Place, publisher, year, edition, pages
Pergamon Press, 2018
Keywords
Tautomers, FTIR spectra, UV-vis spectra, NMR spectra, DFT calculations
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-232582 (URN)10.1016/j.saa.2018.05.096 (DOI)000437816000040 ()29879648 (PubMedID)2-s2.0-85047933840 (Scopus ID)
Funder
Carl Tryggers foundation , CTS 17:514Stiftelsen Olle Engkvist Byggmästare, 189-0223
Note

QC 20180727

Available from: 2018-07-27 Created: 2018-07-27 Last updated: 2018-07-27Bibliographically approved
Zavaraki, A. J., Huang, J., Ji, Y. & Ågren, H. (2018). Low toxic Cu2GeS3/InP quantum dot sensitized infrared solar cells. Journal of Renewable and Sustainable Energy, 10(4), Article ID 043710.
Open this publication in new window or tab >>Low toxic Cu2GeS3/InP quantum dot sensitized infrared solar cells
2018 (English)In: Journal of Renewable and Sustainable Energy, ISSN 1941-7012, E-ISSN 1941-7012, Vol. 10, no 4, article id 043710Article in journal (Refereed) Published
Abstract [en]

Type-II Cu2GeS3/InP core/shell quantum dots (QDs) are designed using density functional theory and synthesized by a hot injection method in order to enhance the power conversion efficiency of quantum dot sensitized solar cells. The low toxicity and an absorption extending to the infrared region are key aspects of the importance of these QDs. The longer absorption achieved for type-II Cu2GeS3/InP QDs compared to single core Cu2GeS3 QDs is achieved by optimization of the band alignment. This leads to a more efficient carrier separation and a suppression of the electron-hole recombination. The results show that the efficiency and the electron injection rate constant increase by more than 5 and 2 times, respectively.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2018
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-240217 (URN)10.1063/1.5044608 (DOI)000443601600037 ()2-s2.0-85052677166 (Scopus ID)
Note

QC 20181217

Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2018-12-17Bibliographically approved
Li, D., Ågren, H. & Chen, G. (2018). Near infrared harvesting dye-sensitized solar cells enabled by rare-earth upconversion materials. Dalton Transactions, 47(26), 8526-8537
Open this publication in new window or tab >>Near infrared harvesting dye-sensitized solar cells enabled by rare-earth upconversion materials
2018 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 47, no 26, p. 8526-8537Article, review/survey (Refereed) Published
Abstract [en]

Dye-sensitized solar cells (DSSCs) have been deemed as promising alternatives to silicon solar cells for the conversion of clean sunlight energy into electricity. A major limitation to their conversion efficiency is their inability to utilize light in the infrared (IR) spectral range, which constitutes almost half the energy of the sun's radiation. This fact has elicited motivations and endeavors to extend the response wavelength of DSSCs to the IR range. Photon upconversion through rare-earth ions constitutes one of the most promising approaches toward the goal of converting near-IR (NIR) or IR light into visible or ultraviolet light, where DSSCs typically have high sensitivity. In the present review, we summarize recent progress based on the utilization of various upconversion materials and device structures to improve the performance of dye-sensitized solar cells.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-232388 (URN)10.1039/c7dt04461e (DOI)000437317700004 ()29388652 (PubMedID)2-s2.0-85049430338 (Scopus ID)
Note

QC 20180727

Available from: 2018-07-27 Created: 2018-07-27 Last updated: 2018-07-27Bibliographically approved
Huang, B., Bergstrand, J., Duan, S., Zhan, Q., Widengren, J., Ågren, H. & Liu, H. (2018). Overtone Vibrational Transition-InducedLanthanide Excited-State Quenching in Yb3+/Er3+-Doped Upconversion Nanocrystals [Letter to the editor]. ACS Nano, 12, 10572-10575
Open this publication in new window or tab >>Overtone Vibrational Transition-InducedLanthanide Excited-State Quenching in Yb3+/Er3+-Doped Upconversion Nanocrystals
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2018 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, p. 10572-10575Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-239728 (URN)10.1021/acsnano.8b05095 (DOI)
Note

QC 20181217

Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2018-12-17Bibliographically approved
Kuklin, A. V., Baryshnikov, G. V., Minaev, B. F., Ignatova, N. & Ågren, H. (2018). Strong Topological States and High Charge Carrier Mobility in Tetraoxa[8]circulene Nanosheets. The Journal of Physical Chemistry C, 122(38), 22216-22222
Open this publication in new window or tab >>Strong Topological States and High Charge Carrier Mobility in Tetraoxa[8]circulene Nanosheets
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 38, p. 22216-22222Article in journal (Refereed) Published
Abstract [en]

Here we report structural and electronic properties of a new family of two-dimensional covalent metal-free organic frameworks based on tetraoxa[8]circulene with different types of fusing. All nanosheets demonstrate high thermodynamic stability and unique electronic properties depending on the fusing type. Among three types of nanosheets, only two demonstrate semiconducting properties exhibiting 1.37 and 1.84 eV direct band gaps, while another one is found to be a semimetal, which hosts strong topological states and enhances the band gap (∼87 meV) induced by spin-orbit coupling that exceeds by several orders of magnitude that gap in graphene. Tetraoxa[8]circulene-based nanosheets are also predicted to be good organic semiconductors due to a clearly observable quantum confinement effect on the band gap size in oligomers and relatively low effective masses, which result in high carrier mobility. Owing to the versatility of chemical design, these materials have the potential to expand applications beyond those of graphene.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
Carrier mobility, Electronic properties, Graphene, Nanosheets, Topology, High carrier mobility, Orders of magnitude, Quantum confinement effects, Semi-conducting property, Spin-orbit couplings, Structural and electronic properties, Tetraoxa[8]circulene, Topological state, Energy gap
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-236349 (URN)10.1021/acs.jpcc.8b08596 (DOI)000446141900057 ()2-s2.0-85053683437 (Scopus ID)
Note

QC 20181108

Available from: 2018-11-08 Created: 2018-11-08 Last updated: 2018-11-08Bibliographically approved
Gusev, A. N., Shul'gin, V. F., Braga, E. V., Nemec, I., Minaev, B. F., Baryshnikov, G. V., . . . Linert, W. (2018). Synthesis and photophysical properties of Zn(II) Schiff base complexes possessing strong solvent-dependent solid-state fluorescence. Polyhedron, 155, 202-208
Open this publication in new window or tab >>Synthesis and photophysical properties of Zn(II) Schiff base complexes possessing strong solvent-dependent solid-state fluorescence
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2018 (English)In: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 155, p. 202-208Article in journal (Refereed) Published
Abstract [en]

The present article reports on the syntheses, crystal structures and luminescence properties of three solvate forms of a zinc(II) complex containing 4-{(E)-[(2-fluorophenyl)imino]methyl}-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one (HL). The reaction of zinc(II)acetate with the HL ligand in ethanol and acetonitrile led to the formation of two solvate analogues [Zn(L)2]·Solv (Solv – ethanol (1) and acetonitrile (2)). The properties of the [Zn(L)2]·Solv complexes were investigated by UV–Vis absorption and fluorescence emission spectroscopy, and the density functional theory calculations. Bader's topological analysis was performed to investigate the electronic peculiarities of Zn(II) polyhedra and non-covalent interactions within crystal packing of studied solvates.

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Crystal structures, Density functional theory, Photophysical properties, Schiff base, Zinc(II) complex
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-236590 (URN)10.1016/j.poly.2018.08.019 (DOI)000449137000025 ()2-s2.0-85052641720 (Scopus ID)
Note

Export Date: 22 October 2018; Article; CODEN: PLYHD; Correspondence Address: Gusev, A.N.; N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of SciencesRussian Federation; Funding details: № 3874, Minobrnauka, Ministry of Education and Science of the Russian Federation; Funding details: № 16-03-00386, RFBR, Russian Foundation for Basic Research; Funding details: SNIC 2017-12-49, Stiftelsen Olle Engkvist Byggmästare; Funding details: 189-0223, Stiftelsen Olle Engkvist Byggmästare; Funding details: CTS 17:514; Funding details: LO1305; Funding text: Authors would like to acknowledge the financial support from the Russian Foundation for Basic Research (project № 16-03-00386) and Ministry of Education and Science of Russian Federation (project № 3874). G.B. and H.A. acknowledge for support to the Carl Tryggers Foundation (Grant No. CTS 17:514 ) and Olle Engkvist Byggmästare foundation (contract No. 189-0223). The quantum–chemical calculations were performed with computational resources provided by the High Performance Computing Center North (HPC2N) which is a Swedish national center for Scientific and Parallel Computing through the project “Multiphysics Modeling of Molecular Materials” SNIC 2017-12-49. IN and ZT acknowledge financial support going from The Ministry of Education, Youth and Sports of the Czech Republic ( LO1305 ). Appendix A. QC 20181126

Available from: 2018-11-26 Created: 2018-11-26 Last updated: 2018-11-26Bibliographically approved
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