Time‐dependent density functional theory study on the hydrogen bonding‐induced twisted intramolecular charge‐transfer excited states of 2‐(4′‐N,N‐dimethylaminophenyl)imidazo[4,5‐b]pyridine

Yin, Shi; Liu, Yufang; Zhang, Wei; Guo, Mingxia; Song, Ping

doi:10.1002/jcc.21492

Cited by 25 publications

(2 citation statements)

References 87 publications

(152 reference statements)

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“…DMAPIP-b exhibits a longer-wavelength emission only in protic solvents. The intermolecular proton-transfer-induced TICT emission in DMAPIP-b and the role of pyridyl nitrogen and imidazole “NH” group were established. ,, The dual emissions in DMAPIP-b in protic solvents were replaced by single emissions when pyridyl nitrogen or imidazole nitrogen was methylated to block the intermolecular proton transfer . Also, the fluorescence lifetime and fluorescence quantum yield of DMAPIP-b and its imidazole nitrogen methylated compound are less in methanol compared to other solvents, whereas the fluorescence lifetime and fluorescence quantum yield of the pyridyl nitrogen methyl derivative are comparable in different solvents. , The Taft parameter α, the hydrogen-bond-donating ability of the solvent stabilizes both DMAPIP-b and its imidazole nitrogen methyl derivative .…”

Section: Resultsmentioning

confidence: 99%

Light-Driven Switching between Intramolecular Proton-Transfer and Charge-Transfer States

2021

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A molecular photoswitch, 2-(4′-diethylamino-2′-hydroxyphenyl)-1Himidazo-[4,5-b]pyridine (DHP), with mutually independent paths of excited-state intramolecular proton transfer (ESIPT) and twisted intramolecular charge transfer (TICT) was developed. Control over these processes was attained by switching the solvents. Depending on the solvent's hydrogen-bond capacity and polarity, either one of the photoprocesses (ESIPT or TICT) or both can be triggered. Accordingly, normal and tautomer emissions, normal and TICT emissions, or triple emission of normal, tautomer, and TICT were obtained from the molecule. The emissions were resolved by fluorescence lifetime. The conclusions were established by synthesizing and studying the methoxy derivative of the molecule.

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Section: Resultsmentioning

confidence: 99%

Light-Driven Switching between Intramolecular Proton-Transfer and Charge-Transfer States

2021

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“…TDDFT method is good for electronic structure calculations in the excited states for large molecular systems due to its moderate efficiency and accuracy. [32][33][34][35][36] But optimization by TDDFT method gives an incorrect ordering of energies in a few cases. 37 The geometries as well as molecular properties obtained at the CIS level are quite reasonable and correct, at least as a first approximation for a variety of molecules.…”

Section: Spectral Measurementsmentioning

confidence: 99%

Modulation of the photophysics of 2-(4′-N,N-dimethylaminophenyl)imidazo-[4,5-b]pyridine by long chain N-alkylations

Dash

Krishnamoorthy

2011

Photochem Photobiol Sci

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The N-alkylated products of 2-(4'-N,N-dimethylaminophenyl)imidazo[4,5-b]pyridine (DMAPIP-b) were synthesized to study the effect of long alkyl chains on the photophysics of the fluorophore. Two different compounds were synthesized: in molecule 1, the alkyl chain was attached to the pyridine nitrogen of DMAPIP-b and in molecule 2 the alkyl chain was substituted on the imidazole nitrogen of DMAPIP-b. Absorption, steady state and time-resolved fluorescence techniques were employed to investigate the spectral properties in different solvents. Density functional theory (DFT) and restricted configuration by singles (CIS) combined with time-dependent DFT (TDDFT) calculations were performed on the ground state and the excited state respectively to calculate the geometrical and the electronic properties of the molecules. Unlike DMAPIP-b, where dual emission was observed in protic solvents, which originates from both a locally excited state and an intramolecular charge transfer (ICT) state, the pyridine nitrogen alkylated product (1) emits a single emission from the ICT state and the imizadole nitrogen alkylated molecule (2) emits dual emission only in methanol and water.

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A TD‐DFT study on the hydrogen bonding of three esculetin complexes in electronically excited states: Strengthening and weakening

et al. 2011

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Time-dependent density functional theory (TD-DFT) method was used to study the excited-state hydrogen bonding of three esculetin complexes formed with aprotic solvents. The geometric structures, molecular orbitals (MOs), electronic spectra and the infrared (IR) spectra of the three doubly hydrogen-bonded complexes formed by esculetin and aprotic solvents dimethylsulfoxide (DMSO), tetrahyrofuran (THF) and acetonitrile (ACN) in both ground state S(0) and the first singlet excited state S(1) were calculated by the combined DFT and TD-DFT methods with the COSMO solvation model. Two intermolecular hydrogen bonds can be formed between esculetin and the aprotic solvent in each hydrogen-bonded complex. Based on the calculated bond lengths of the hydrogen bonds and the groups involved in the formation of the intermolecular hydrogen bonds in different electronic states, it is demonstrated that one of the two hydrogen bonds formed in each hydrogen-bonded complex is strengthened while the other one is weakened upon photoexcitation. Furthermore, it is found that the strength of the intermolecular hydrogen bonds formed in the three complexes becomes weaker as the solvents change from DMSO, via THF, to ACN, which is suggested to be due to the decrease of the hydrogen bond accepting (HBA) ability of the solvents. The spectral shifts of the calculated IR spectra further confirm the strengthening and weakening of the intermolecular hydrogen bonds upon the electronic excitation. The variations of the intermolecular hydrogen bond strengths in both S(0) and S(1) states are proposed to be the main reasons for the gradual spectral shifts in the absorption and fluorescence spectra both theoretically and experimentally.

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Time‐dependent density functional theory study on the hydrogen bonding‐induced twisted intramolecular charge‐transfer excited states of 2‐(4′‐N,N‐dimethylaminophenyl)imidazo[4,5‐b]pyridine

Cited by 25 publications

References 87 publications

Light-Driven Switching between Intramolecular Proton-Transfer and Charge-Transfer States

Light-Driven Switching between Intramolecular Proton-Transfer and Charge-Transfer States

Modulation of the photophysics of 2-(4′-N,N-dimethylaminophenyl)imidazo-[4,5-b]pyridine by long chain N-alkylations

A TD‐DFT study on the hydrogen bonding of three esculetin complexes in electronically excited states: Strengthening and weakening

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