Browsing by Author "Yan, Linyin"

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A phenothiazine-based colorimetric chemodosimeter for the rapid detection of cyanide anions in organic and aqueous media
(2014)
Garg, Bhaskar
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Yan, Linyin
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Bisht, Tanuja
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Zhu, Chaoyuan
;
Ling, Yong-Chien
A novel, phenothiazine-based chemodosimeteric probe PCP 1 has been developed and studied as a cyanide selective indicator in organic and aqueous media. Complete colour bleaching was observed due to nucleophilic addition of cyanide to the tricyanovinyl moiety of PCP 1, which results in the disruption of the extended conjugate and turn-off the intramolecular charge transfer process.
Excited-state localization and energy transfer in pyrene core dendrimers with fluorene/carbazole as the dendrons and acetylene as the linkages
(2016-02-07)
Yan, Linyin
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Wan, Yan
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Xia, Andong
;
Lin, Sheng Hien
;
Huang, Ran
A multi-leveled theoretical investigation combining TD-DFT (B3LYP and CAM-B3LYP) methods and a semi-empirical method was conducted to determine the structure-related spectral properties of T-series dendrimers composed of nearly hundreds of atoms, based on a proposed molecular model. Both one-and two-photon absorption spectra of the dendrimer molecules were well reproduced. The "antenna effect" in the dendrimers molecule was theoretically studied. The process of excitation energy localization from chromophores in the branches to the pyrene core before the fluorescence emission was visualized using contours of the charge different density (CDD) between the electronic states. Conclusions based on the theoretical model were drawn about the observed photophysical properties of T-series dendrimers as follows: (a) increasing the generation of a branch would enhance the absorption of photons with a wavelength below 430 nm; (b) enlarging the conjugation of branches would enhance the coupling among the chromophores and would lower the excitation energy; (c) the existence of inter-molecular coupling among the "antenna" chromophores in conjugated branches and the pyrene core would significantly promote two-photon absorption.
Localized Emitting State and Energy Transfer Properties of Quadrupolar Chromophores and (Multi)Branched Derivatives
(1970-01-01)
Yan, Linyin
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Chen, Xudong
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He, Qingguo
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Wang, Yingying
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Wang, Xuefei
"In order to better understand the nature of intramolecular charge and energy transfer in multibranched molecules, we have synthesized and studied the photophysical properties of a monomer quadrupolar chromophore with donor-acceptor-donor (D-A-D) electronic push-pull structure, together with its V-shaped dimer and star-shaped trimers. The comparison of steady-state absorption spectra and fluorescence excitation anisotropy spectra of these chromophores show evidence of weak interaction (such as charge and energy transfer) among the branches. Moreover, similar fluorescence and solvation behavior of monomer and branched chromophores (dimer and trimer) implies that the interaction among the branches is not strong enough to make a significant distinction between these molecules, due to the weak interaction and intrinsic structural disorder in branched molecules. Furthermore, the interaction between the branches can be enhanced by inserting pi bridge spacers (-C=C- or -C C-) between the core donor and the acceptor. This improvement leads to a remarkable enhancement of two photon cross sections, indicating that the interbranch interaction results in the amplification of transition dipole moments between ground states and excited states. The interpretations of the observed photophysical properties are further supported by theoretical investigation, which reveal that the changes of the transition dipole moments of the branched quadrupolar chromophores play a critical role in observed the two-photon absorption (2PA) cross-section for an intramolecular charge transfer (ICT) state interaction in the multibranched quadrupolar chromophores."
Magnetism-tuning strategies for graphene oxide based on magnetic oligoacene oxide patches model
(2018-02-07)
Wen, Yanjie
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Yen, Chia-Liang
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Yan, Linyin
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Kono, Hirohiko
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Lin, Sheng-Hsien
Graphene oxide (GO) has wide application potential owing to its 2D structure and diverse modification sites for various targeted uses. The introduction of magnetism into GO structures has further advanced the controllability of the application of GO materials. Herein, the concept of modular design and modeling was applied to tune the magnetism of GO. To obtain desirable magnetic properties, diradicalstructured GO patches were formed by the introduction of two functional groups to break the Kekule structure of the benzene ring. In these diradical GO patches, the energy of the triplet state was lower than those of the open-shell broken-symmetry singlet state and closed-shell singlet state. To create such multi-radical patches, a practical approach is to determine a substantial spatial separation of the alpha and beta spin densities in the molecule. Thus, systematic design strategies and tests were evaluated. The first strategy was extending the distance between the distribution center of the alpha and beta spin densities; the second was controlling the delocalization directions of the alpha and beta electrons; the third was controlling the delocalization extension of the alpha and beta electrons by oxidative modification, and finally introducing multi-radical structures into the molecular system and controlling the position of each radical. Herein, successful paves the way to explore ferromagnetic MGO guided by theoretical study, which may become reality soon.
The molecular structures and spectroscopic properties of the ground state and the first excited state of pVP
(2017-10-01)
Wu, Lidan
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Yan, Linyin
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Xia, Andong
;
Lin, ShengHien
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應用化學系
P-vinylphenol (pVP) is a common building block of a large number of fluorescent protein chromophores. Theoretical investigation employed TD-DFT calculation has been carried out on pVP molecule to reveal the structural properties that influence the absorption and fluorescence. The molecular structures of the first excited state (S-1) as well as the ground state (S-0) have been optimized. Based on these structures, the absorption spectra are simulated using the Franck-Condon factors and displaced-distorted harmonic oscillator model. The result agrees well with the reported experiment data. It's also found that the S-0 -> S-1 transition is a significant pi -> pi* transition. Besides the pi electrons on the benzene ring, the pi electron together with the lone pair electron on hydroxyl group takes parts in the transition. Therefore the absorption of pVP would be modulated not only by the isomerization but also by the intermolecular hydrogen bond. (C) 2017 Elsevier B.V. All rights reserved.