A TD‐DFT Study on the Effect of Intermolecular Hydrogen Bonding on the Photophysical Properties of N‐Methyl‐1,8‐naphthalimide |
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Authors: | Da‐Peng Yang Hui Li Yu‐Fang Liu |
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Institution: | 1. Physics Laboratory, North China University of Water Resources and Electric Power, Zhengzhou 450011, P. R. China;2. Department of Physics, Henan Normal University, Xinxiang 453007, P. R. China |
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Abstract: | The effect of intermolecular hydrogen bonding on the photophysical properties of N‐methyl‐1,8‐naphthalimide ( 2 ) has been investigated by time‐dependent density functional theory (TD‐DFT) method. The UV and IR spectra of 2 monomer and its hydrogen‐bonded complexes formed with 2,2,2‐trifluoroethanol (TFE) 2 +TFE and 2 +2TFE have been calculated, which confirm the presence of intermolecular hydrogen bonding interactions between the carbonyl groups of the aromatic imide and the hydroxyl group of the polyfluorinated alcohol. The absorption and fluorescence intensities going from 2 monomer via hydrogen‐bonded complex 2 +TFE to 2 +2TFE were found to be gradually enhanced with the wavelength gradually red‐shifted. The enhancements of the fluorescence intensities from 2 monomer to hydrogen‐bonded complexes 2 +TFE and 2 +2TFE were attributed to the decrease of the intersystem crossing (ISC) efficiency from the first excited singlet state S1 1(ππ*) to the second excited triplet state T2 3(nπ*), whose energy was increased relative to its ground state due to the intermolecular hydrogen bonding interactions. |
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Keywords: | Intermolecular hydrogen bonding Intersystem crossing (ISC) Photophysical properties TD‐DFT |
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