Wyniki wyszukiwania - Biblioteka Nauki

1

A theoretical study on the red- and blue-shift hydrogen bonds of cis-trans formic acid dimer in excited states

100%

Yang D. , Yang Y. , Liu Y.

Open Chemistry

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2013

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tom 11

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nr 2

171-179

EN

The excited states of cis-trans formic acid dimer and its monomers have been investigated by time-dependent density functional theory (TDDFT) method. The formation of intermolecular hydrogen bonds O1-H1...O2=C2 and C2-H2...O4=C1 induces bond length lengthening of the groups related to the hydrogen bond, while that of the C2-H2 group is shortened. It is demonstrated that the red-shift hydrogen bond O1-H1...O2=C2 and blue-shift hydrogen bond C2-H2...O4=C1 are both weakened when excited to the S1 state. Moreover, it is found that the groups related to the formation of red-shift hydrogen bond O1-H1...O2=C2 are both strengthened in the S1 state, while the groups related to the blue-shift hydrogen bond C2-H2...O4=C1 are both weakened. This will provide information for the photochemistry and photophysical study of red- and blue-shift hydrogen bond. [...]

2

Experimental and theoretical study of 1, 4-naphthoquinone based dye in dye-sensitized solar cells using ZnO photoanode

100%

Shinde D. , Tambade P. , Pathan H. , Gadave K.

Materials Science Poland

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2017

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tom Vol. 35, No. 4

746--754

EN

A dye-sensitized solar cell (DSSC) was assembled using a dye 4-(3-chloro-1, 4-dioxo-1, 4-dihydronaphthalen-2-ylamino) benzoic acid with ZnO as a photo anode. It was synthesized using 2, 3-dichloro 1, 4-naphthoquinone and p-amino benzoic acid. The spectral features of the dye were analyzed in ethanol using experimental and computational methods. The theoretical investigations revealed that the synthesized dye may act as a sensitizer in DSSCs. The photo electrochemical performance was tested under direct sunlight using a sandwich type DSSC. The photovoltaic data of the dye adsorbed on ZnO films indicated the power conversion efficiency of 1.07 % under sunlight with a light intensity of 39 mW·cm-2.

3

A theoretical forecast of the hydrogen bond changes in the electronic excited state for BN and its derivatives

100%

Wang D. , Hao C. , Wang S. , Dong H. , Qiu J.

Open Physics

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2012

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tom 10

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nr 1

116-123

EN

The relationship between electronic spectral shifts and hydrogen-bonding dynamics in electronically excited states of the hydrogen-bonded complex is put forward. Hydrogen bond strengthening will induce a redshift of the corresponding electronic spectra, while hydrogen bond weakening will cause a blueshift. Time-dependent density function theory (TDDFT) was used to study the excitation energies in both singlet and triplet electronically excited states of Benzonitrile (BN), 4-aminobenzonitrile (ABN), and 4-dimethylaminobenzonitrile (DMABN) in methanol solvents. Only the intermolecular hydrogen bond C≡N...H-O was involved in our system. A fairly accurate forecast of the hydrogen bond changes in lowlying electronically excited states were presented in light of a very thorough consideration of their related electronic spectra. The deduction we used to depict the trend of the hydrogen bond changes in excited states could help others understand hydrogen-bonding dynamics more effectively.

4

Experimental and Theoretical Investigation to Study the Molecular Structure, Electronic Properties, UV–Vis Spectra of Coumarin 102

100%

Mohi A. T. , Abood T. H. , Hadi H. A. , Karim M. S. , Mutlik F. A.-H. , Alwan T. J.

World Scientific News

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2017

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tom 70

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nr 2

216-229

EN

In this work, we study the structure, electronic properties and electronic spectra of Coumarin 102 (C102) dissolved in ethanol as an experimental-theoretical investigation. The various properties of the ground and excited electronic states of coumarins 102 using density functional theory (DFT) and time-dependent density functional theory (TDDFT) was calculated by the B3LYP density functional model with 6-31G(d,p) basis set by Gaussian 09 W program. Spectral characteristics of coumarin 102 have been probed into by methods of experimental UV-visible, and quantum chemistry. The UV spectrum was measured in Ethanol. The optimized structures, total energies, electronic states (HOMO- LUMO), energy gap, ionization potentials, electron affinities, chemical potential, global hardness, softness, global electrophilictity, dipole moment and electrostatic potential was calculated. were calculated. We find good agreement between experimental data of UV spectrum and TDDFT excitation energies.

5

Enhancement of electronic, photophysical and optical properties of 5,5′-Dibromo-2,2′-bithiophene molecule : new aspect to molecular design

100%

Muz İ. , Kurban M.

Opto-Electronics Review

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2019

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tom Vol. 27, No. 2

113--118

EN

The aims of this study were to enhance electronic, photophysical and optical properties of molecular semiconductors. For this purpose, the isomers of the B-doped molecule (5,5′-Dibromo-2,2′-bithiophene) have been investigated by density functional theory (DFT) based on B3LYP/6-311++G** level of theory. The isomers were first calculated using kick algorithm. The most stable isomers of the B-doped molecule are presented depending on the binding energy, fragmentation energy, ionization potential, electron affinity, chemical hardness, refractive index, radial distribution function and HOMO-LUMO energy gap based on DFT. Ultraviolet-visible (UV–vis) spectra have been also researched by time-dependent (TD) DFT calculations. The value of a band gap for isomer with the lowest total energy decreases from 4.20 to 3.47 eV while the maximum peaks of the absorbance and emission increase from 292 to 324 nm and 392 to 440 nm with boron doped into 5,5′-Dibromo-2,2′-bithiophene. Obtained results reveal that the B-doped molecule has more desirable optoelectronic properties than the pure molecule.

6

Role of Substituents in Excited State Intramolecular Proton Transfer (ESIPT) Processes

86%

Sepioł J.

Polish Journal of Chemistry

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2009

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tom Vol. 83, nr 10

1671-1692

EN

The increasing interest in molecular systems exhibiting ESIPT reaction has triggered – due to their broad field of potential applications – an extensive search for properly substituted compounds with well-tailored properties. This review is based on selected papers dealing with some commonly known ESIPT systems modified by specific substituents. The results of several studies concerning the rate of ultrafast ESIPT reactions in supersonic molecular beams are presented. Articles reporting on phototautomeric fluorescence in solutions illustrated a big role of substituents, which influence the emission quantum yield. Theoretical works pointed to the increasing role of advanced calculations in predicting and understanding the structural, electronic, and spectroscopic properties of diverse ESIPT-capable compounds.