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Publications (10 of 619) Show all publications
Li, X., Baryshnikov, G. V., Deng, C., Bao, X., Wu, B., Zhou, Y., . . . Zhu, L. (2019). A three-dimensional ratiometric sensing strategy on unimolecular fluorescence-thermally activated delayed fluorescence dual emission. Nature Communications, 10, Article ID 731.
Open this publication in new window or tab >>A three-dimensional ratiometric sensing strategy on unimolecular fluorescence-thermally activated delayed fluorescence dual emission
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2019 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 731Article in journal (Refereed) Published
Abstract [en]

Visualized sensing through fluorescence signals is a powerful method for chemical and physical detection. However, the utilization of fluorescent molecular probes still suffers from lack of precise signal self-calibration in practical use. Here we show that fluorescence and thermally activated delayed fluorescence can be simultaneously produced at the single-molecular level. The thermally activated delayed fluorescence serves as a sensing signal with its wavelength and lifetime both altered correlating to polarity, whereas the fluorescence always remains unchanged as an internal reference. Upon the establishment of a three-dimensional working curve upon the ratiometric wavelength and photoluminescence lifetime vs. polarity, disturbance factors during a relevant sensing process can be largely minimized by such a multiple self-calibration. This strategy was further applied into a precise detection of the microenvironmental polarity variation in complex phospholipid systems, towards providing new insights for convenient and accurate diagnosis of membrane lesions.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-245138 (URN)10.1038/s41467-019-08684-2 (DOI)000458567500011 ()30760723 (PubMedID)2-s2.0-85061511851 (Scopus ID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-06-11Bibliographically approved
Baryshnikov, G. V., Valiev, R. R., Cherepanov, V. N., Karaush-Karmazin, N. N., Minaeva, V. A., Minaev, B. F. & Ågren, H. (2019). Aromaticity and photophysics of tetrasila- and tetragerma-annelated tetrathienylenes as new representatives of the hetero[8]circulene family. Physical Chemistry, Chemical Physics - PCCP, 21(18), 9246-9254
Open this publication in new window or tab >>Aromaticity and photophysics of tetrasila- and tetragerma-annelated tetrathienylenes as new representatives of the hetero[8]circulene family
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2019 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 18, p. 9246-9254Article in journal (Refereed) Published
Abstract [en]

The electronic structure, absorption and emission spectra, aromaticity and photophysical behavior of the recently synthesized tetrasilatetrathia[8]circulene and tetragermatetrathia[8]circulene compounds have been studied computationally. Both compounds demonstrate a specific bifacial aromaticity, which is unusual for hetero[8]circulenes; the inner eight-membered core sustains an expected strong paratropic magnetically-induced ring current, while the outer perimeter contains saturated Si(Et)(2) and Ge(Et)(2) moieties which break the conjugation between the thiophene rings. The overall magnetically-induced ring current for both studied circulenes is close to zero because of the strong local diatropic currents in each thiophene ring that compensate the paratropic counterpart. The electronic absorption and emission spectra of tetrasilatetrathia[8]circulene and tetragermatetrathia[8]circulene demonstrate a clear visible vibronic progression. The 0-0 band is the most active one in the absorption spectra, while in the fluorescence spectra the 0-1 band composed of several normal vibrations is more intense compared with the 0-0 band in excellent agreement with experiment. Accounting for spin-orbit coupling effects, an analysis of the photophysical constants for the two compounds demonstrates: (1) a clear manifestation of the internal heavy atom effect on the inter-system crossing efficiency; (2) one to two order domination of non-radiative rates over the fluorescence rate; and (3) that the S-1-S-0 internal conversion is extremely slow and can not compete with the fluorescence, while the S-1-T-n inter-system crossing is a main deactivation channel of the S-1 excited state. These results provide new insight into the electronic structure and photophysics of tetrasilatetrathia[8]circulene and tetragermatetrathia[8]circulene as novel standalone representatives of hetero[8]circulenes - tetraannelated derivatives of tetrathienylene.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-255455 (URN)10.1039/c9cp01608b (DOI)000472922500024 ()31012469 (PubMedID)2-s2.0-85065621689 (Scopus ID)
Note

QC 20190822

Available from: 2019-08-22 Created: 2019-08-22 Last updated: 2019-10-10Bibliographically approved
Bagheri, S., Liu, Q., Bergstrand, J., Pu, R., Zhan, Q., Ara, M. H., . . . Widengren, J. (2019). Change in the emission saturation and kinetics of upconversion nanoparticles under different light irradiations. Optical materials (Amsterdam), 97, Article ID 109389.
Open this publication in new window or tab >>Change in the emission saturation and kinetics of upconversion nanoparticles under different light irradiations
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2019 (English)In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 97, article id 109389Article in journal (Refereed) Published
Abstract [en]

Nd3+-sensitized upconversion nanoparticles (UCNPs) can be excited by both 980 and 808 nm light, which is regarded as a particularly advantageous property of these particles. In this work, we demonstrate that the nanoparticles can exhibit significantly different response when excited at these two excitation wavelengths, showing dependence on the intensity of the excitation light and the way it is distributed in time. Specifically, with 808 nm excitation saturation in the emitted luminescence is more readily reached with increasing excitation intensities than upon 980 nm excitation. This is accompanied by delayed upconversion luminescence (UCL) kinetics and weaker UCL intensities. The different luminescence response at 808 and 980 nm excitation reported in this work is relevant in a manifold of applications using UCNPs as labels and sensors. This could also open new possibilities for multi-wavelength excitable UCNPs for upconversion color display and in laser-scanning microscopy providing selective readouts and sub-sectioning of samples.

Place, publisher, year, edition, pages
Elsevier B.V., 2019
Keywords
Color tunability, Kinetics, Laser scanning microscopy, Saturation, Upconversion, Enzyme kinetics, Laser applications, Luminescence, Nanoparticles, Saturation (materials composition), Excitation intensity, Excitation wavelength, Multi-wavelengths, Up-conversion, Upconversion luminescence, Upconversion nanoparticles, Light
National Category
Theoretical Chemistry Atom and Molecular Physics and Optics
Research subject
Theoretical Chemistry and Biology; Physics, Theoretical Physics
Identifiers
urn:nbn:se:kth:diva-263500 (URN)10.1016/j.optmat.2019.109389 (DOI)2-s2.0-85072543021 (Scopus ID)
Funder
Swedish Research Council, 2016-03804Swedish Foundation for Strategic Research , SSF ITM17-0491ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 19-424
Note

QC20191205

Available from: 2019-12-05 Created: 2019-12-05 Last updated: 2019-12-05Bibliographically approved
Zakomirnyi, V., Ershov, A., Grasimov, V., Karpov, S., Ågren, H. & Rasskazov, I. (2019). Collective lattice resonances in arrays of dielectric nanoparticles: a matter of size. Optics Letters, 44(23), 5743-5746
Open this publication in new window or tab >>Collective lattice resonances in arrays of dielectric nanoparticles: a matter of size
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2019 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 44, no 23, p. 5743-5746Article in journal (Refereed) Published
Abstract [en]

Collective  lattice  resonances  (CLRs)  in  finite-sized  2Darrays of dielectric nanospheres have been studied via the coupled dipole approximation. We show that even for sufficiently large arrays, up to 100×100 nanoparticles (NPs),electric or magnetic dipole CLRs may differ significantly from the ones calculated for infinite arrays with the same NP  sizes  and  interparticle  distances.  The  discrepancy  is explained  by  the  existence  of  a  sufficiently  strong  cross-interaction between electric and magnetic dipoles inducedat NPs in finite-sized lattices, which is ignored for infinite arrays.  We  support  this  claim  numerically  and  propose an analytic model to estimate a spectral width of CLRs for finite-sized arrays. Given that most of the current theoretical and numerical researches on collective effects in arrays of dielectric NPs rely on modeling infinite structures, there ported findings may contribute to thoughtful and optimal design of inherently finite-sized photonic devices.

National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-264493 (URN)10.1364/OL.44.005743 (DOI)
Note

QC 20191204

Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2019-12-04Bibliographically approved
Zakomirnyi, V., Karpov, S. V., Ågren, H. & Rasskazov, I. L. (2019). Collective lattice resonances in disordered and quasi-random all-dielectric metasurfaces. Journal of the Optical Society of America. B, Optical physics, 36(7), E21-E29
Open this publication in new window or tab >>Collective lattice resonances in disordered and quasi-random all-dielectric metasurfaces
2019 (English)In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 36, no 7, p. E21-E29Article in journal (Refereed) Published
Abstract [en]

Collective lattice resonances in disordered 2D arrays of spherical Si nanoparticles (NPs) have been thoroughly studied within the framework of the coupled dipole approximation. Three types of defects have been analyzed: positional disorder, size disorder, and quasi-random disorder. We show that the positional disorder strongly suppresses either the electric dipole (ED) or the magnetic dipole (MD) coupling, depending on the axis along which the NPs are shifted. Contrarily, size disorder strongly affects only the MD response, while the ED resonance can be almost intact, depending on the lattice configuration. Finally, random removing of NPs from an ordered 2D lattice reveals a quite surprising result: hybridization of the ED and MD resonances with lattice modes remains observable even in the case of random removing of up to 84% of the NPs from the ordered array. The reported results could be important for rational design and utilization of metasurfaces, solar cells, and other alldielectric photonic devices. 

Place, publisher, year, edition, pages
Optics Info Base, Optical Society of America, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-255429 (URN)10.1364/JOSAB.36.000E21 (DOI)000473321200004 ()2-s2.0-85069600603 (Scopus ID)
Note

QC 20190815

Available from: 2019-08-15 Created: 2019-08-15 Last updated: 2019-11-29Bibliographically approved
Baryshnikova, A. T., Minaev, B. F., Baryshnikov, G. V. & Ågren, H. (2019). Computational study of the structure and magnetic properties of the weakly-coupled tetranuclear square-planar complex of Cu(II) with a tetraporphyrin sheet. Inorganica Chimica Acta, 485, 73-79
Open this publication in new window or tab >>Computational study of the structure and magnetic properties of the weakly-coupled tetranuclear square-planar complex of Cu(II) with a tetraporphyrin sheet
2019 (English)In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 485, p. 73-79Article in journal (Refereed) Published
Abstract [en]

Owing to the fact that weakly-coupled Cu(II) complexes are potentially applicable in the fields of spintronics and single-molecule magnets we have studied one particularly conspicuous case – a tetranuclear square-planar complex of Cu(II) ions with a π-extended tetraporphyrin ligand (Tetrahedron, 2008, 64, 11433), the structural criteria of which, with very long distances between the paramagnetic centers, can sensibly define the exchange coupling constants and magnetic behaviour. We use the “broken symmetry” density functional theory formalism for various spin states (open-shell singlet, triplet and quintet states). The calculated value of the magnetic exchange integral corresponds to a very weak antiferromagnetic coupling between the neighboring Cu(II) ions (Jcalc = –1.48 cm−1(calculated) Jexp = −1.16 cm−1 (experiment)). The opposite Cu(II) ions are coupled ferromagnetically with an extremely small exchange constant (jcalc = 0.09 cm−1 (calculated) that corresponds to the open-shell singlet ground state of the following spin configuration↑↓↑↓. The exchange mechanism between the [Cu(n) + 4N] localized singly-occupied “magnetic” orbitals of the dxy(Cu) + 4sp2(N) nature indicates a diffuse non-zero overlap between them on the Carbon atoms of the organic ligand. The numerical analysis of atomic spin densities and corresponding decomposition coefficients for the singly-occupied “magnetic” orbitals confirm the proposed exchange mechanism. This superexchange pathway is mediated by the in-plane sp2-hybrid orbitals of the Carbon atoms that couple four [Cu + 4N] fragments by the σ-bond system. For more detailed characterization of the target system a topological analysis of electron density distributions in the high-spin quintet states has been carried out using the Bader's method “quantum theory of atoms in molecules”.

Place, publisher, year, edition, pages
Elsevier S.A., 2019
Keywords
Antiferromagnetic coupling, Bader analysis, Cu(II) complexes, Magnetic exchange, Open-shell singlet, “broken symmetry” approximation
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-248246 (URN)10.1016/j.ica.2018.09.086 (DOI)000448409900011 ()2-s2.0-85054463547 (Scopus ID)
Note

QC 20190411

Available from: 2019-04-11 Created: 2019-04-11 Last updated: 2019-04-11Bibliographically approved
Natarajan Arul, M., Chiotis, K., Rodriguez-Vieitez, E., Lemoine, L., Ågren, H. & Nordberg, A. (2019). Cross-interaction of tau PET tracers with monoamine oxidase B: evidence from in silico modelling and in vivo imaging. European Journal of Nuclear Medicine and Molecular Imaging, 46(6), 1369-1382
Open this publication in new window or tab >>Cross-interaction of tau PET tracers with monoamine oxidase B: evidence from in silico modelling and in vivo imaging
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2019 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 46, no 6, p. 1369-1382Article in journal (Refereed) Published
Abstract [en]

PurposeSeveral tracers have been designed for tracking the abnormal accumulation of tau pathology in vivo. Recently, concerns have been raised about the sources of off-target binding for these tracers; inconclusive data propose binding for some tracers to monoamine oxidase B (MAO-B).MethodsMolecular docking and dynamics simulations were used to estimate the affinity and free energy for the binding of several tau tracers (FDDNP, THK523, THK5105, THK5317, THK5351, T807 [aka AV-1451, flortaucipir], T808, PBB3, RO-948, MK-6240, JNJ-311 and PI-2620) to MAO-B. These values were then compared with those for safinamide (MAO-B inhibitor). PET imaging was used with the tau tracer [F-18]THK5317 and the MAO-B tracer [C-11]DED in five patients with Alzheimer's disease to investigate the MAO-B binding component of this first generation tau tracer in vivo.ResultsThe computational modelling studies identified a binding site for all the tau tracers on MAO-B; this was the same site as that for safinamide. The binding affinity and free energy of binding for the tau tracers to MAO-B was substantial and in a similar range to those for safinamide. The most recently developed tau tracers MK-6240, JNJ-311 and PI-2620 appeared, in silico, to have the lowest relative affinity for MAO-B. The in vivo investigations found that the regional distribution of binding for [F-18]THK5317 was different from that for [C-11]DED, although areas of suspected off-target [F-18]THK5317 binding were detected. The binding relationship between [F-18]THK5317 and [C-11]DED depended on the availability of the MAO-B enzyme.ConclusionsThe developed tau tracers show in silico and in vivo evidence of cross-interaction with MAO-B; the MAO-B component of the tracer binding was dependent on the regional concentration of the enzyme.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Tau PET imaging, Off-target binding, Monoamine oxidase B, Alzheimer's disease, Molecular docking, Binding free energy calculations
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-251698 (URN)10.1007/s00259-019-04305-8 (DOI)000466188800022 ()30919054 (PubMedID)
Note

QC 20190520

Available from: 2019-05-20 Created: 2019-05-20 Last updated: 2019-05-20Bibliographically approved
Wu, H., Chi, W., Baryshnikov, G. V., Wu, B., Gong, Y., Zheng, D., . . . Zhu, L. (2019). Crystal Multi-Conformational Control Through Deformable Carbon-Sulfur Bond for Singlet-Triplet Emissive Tuning. Angewandte Chemie International Edition, 58(13), 4328-4333
Open this publication in new window or tab >>Crystal Multi-Conformational Control Through Deformable Carbon-Sulfur Bond for Singlet-Triplet Emissive Tuning
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2019 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 58, no 13, p. 4328-4333Article in journal (Refereed) Published
Abstract [en]

Crystal-state luminophores have been of great interest in optoelectronics for years, whereas the excited state regulation at the crystal level is still restricted by the lack of control ways. We report that the singlet-triplet emissive property can be profoundly regulated by crystal conformational distortions. Employing fluoro-substituted tetrakis(arylthio)benzene luminophores as prototype, we found that couples of molecular conformations formed during different crystallizations. The deformable carbon-sulphur bond essentially drove the distortion of the molecular conformation and varied the stacking mode, together with diverse non-covalent interactions, leading to the proportional adjustment of the fluorescence and phosphorescence bands. This intrinsic strategy was further applied for solid-state multicolor emissive conversion and mechanoluminescence, probably offering new insights for design of smart crystal luminescent materials.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
crystal engineering, luminescence, molecular stacking, noncovalent interactions, single-crystal conformation
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-249814 (URN)10.1002/anie.201900703 (DOI)000462655400039 ()30706599 (PubMedID)2-s2.0-85062565764 (Scopus ID)
Note

QC 20190423

Available from: 2019-04-23 Created: 2019-04-23 Last updated: 2019-04-23Bibliographically approved
Ågren, H., Harczuk, I. & Vahtras, O. (2019). Decomposition of molecular properties. Physical Chemistry, Chemical Physics - PCCP, 21(5), 2251-2270
Open this publication in new window or tab >>Decomposition of molecular properties
2019 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 5, p. 2251-2270Article in journal (Refereed) Published
Abstract [en]

We review recent work on property decomposition techniques using quantum emical methods and discuss some topical applications in terms of antum mechanics-molecular mechanics calculations and the constructing properties of large molecules and clusters. Starting out from the -called LoProp decomposition scheme [Gagliardi et al., J. Chem. Phys., 04, 121, 4994] for extracting atomic and inter-atomic contributions to lecular properties we show how this method can be generalized to calized frequency-dependent polarizabilities, to localized perpolarizabilities and to localized dispersion coefficients. Some plications of the generalized decomposition technique are reviewed - lculations of frequency-dependent polarizabilities, Rayleigh attering of large clusters, and calculations of hyperpolarizabilities proteins.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-248360 (URN)10.1039/c8cp04340j (DOI)000461667900003 ()30663732 (PubMedID)2-s2.0-85060820802 (Scopus ID)
Note

QC 20190405

Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-05Bibliographically approved
Mudedla, S. K., Natarajan Arul, M., Subramanian, V. & Ågren, H. (2019). Destabilization of amyloid fibrils on interaction with MoS2-based nanomaterials. RSC Advances, 9(3), 1613-1624
Open this publication in new window or tab >>Destabilization of amyloid fibrils on interaction with MoS2-based nanomaterials
2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 3, p. 1613-1624Article in journal (Refereed) Published
Abstract [en]

The present work is motivated by the established concept that the structure and energetics of biomacromolecules can be modulated by confining their dimensions in the nanoscale. In particular, here we use force-field methods to understand the stability of amyloid fibrils at nanostructured interfaces, which can be useful for the development of new therapeutics for Alzheimer's disease. We explore the binding modes and structural properties of fibrils at the interface of molybdenum disulphide nanotubes and the nanosurface using classical molecular dynamics simulations. We find that in general the MoS2 materials induces disruptions in the structure of the amyloid fibrils where the beta sheet conformation of the fibrils changes to a turned conformation, and it is large in the case of nanotubes in comparison to the nanosurfaces. The intermolecular hydrogen bonds, hydrophilic and hydrophobic contacts between the monomer peptides in the fibril are reduced due to their adsorption onto the MoS2 materials, which results in a destabilization of the fibril. The destabilization of fibril is to some extent compensated for by the van der Waals interactions between the fibril and MoS2. Overall the results indicate that MoS2-based materials can be useful in inhibiting the aggregation of smaller protofibrils to matured fibrils and to bust the already formed fibrils. Therapeutic materials should not exhibit any cross interaction with other off-targets compounds. In order to test whether the MoS2 nanomaterial has any such effect we have studied its interaction with two additional biomacromolecules, the human serum albumin and p53 protein, and we report no significant changes in the secondary structure of these biomolecules. Through molecular docking studies we also established that the drug binding ability of HSA is not altered by its surface binding to MoS2 nanosurface.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-244120 (URN)10.1039/c8ra10184a (DOI)000457292800050 ()2-s2.0-85060139369 (Scopus ID)
Note

QC 20190219

Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-02-19Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1763-9383

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