| Anotácia | Betaine 30 is known for the extraordinary solvatochromism of its visible absorption band that goes from lambda=882 nm in tetrachloromethane to lambda=453 nm in water (Delta lambda=similar to 429nm). This large blueshift partly originates from a dramatic decrease of the dipole moment upon excitation. Despite several decades of research, experimental works still disagree on the exact value of the excess dipole moment, the orientation of the dipole moment of the excited-state, the role and amplitude of the change of the polarisability upon excitation as well as on the gas-phase excitation energy. In this work, we present an in-depth theoretical investigation. First, we carefully tested several levels of theory on the model system and next calculated the electric properties of betaine 30 at the CC2 level. Our best estimates are Delta mu = -7 D for the excess dipole moment, that is, a significant decrease but no change of direction, a Delta alpha value of -120 a. u. and a gas-phase vertical excitation energy of 1.127 eV. The implicit solvation models are able to reproduce the experimental trends, with large correlation coefficients for non-hydrogen-bond-donating solvents, the smallest rootmean-square deviation error being reached with the vertical excitation model (VEM). The explicit effective fragment potential method combined with time-dependent density functional theory (TD-DFT) in a QM/MM framework provides accurate estimates for hydrogen-bond-donating solvents, whereas the addition of a dispersion correction is needed to restore the correct solvatochromic direction in tetrachloromethane.
|
|---|
| Kategória ohlasu | BRANDAO, Idney - FRANCO, Leandro R. - FONSECA, Tertius L. - CASTRO, Marcos A. - GEORG, Herbert C. Confirming the relationship between first hyperpolarizability and the bond length alternation coordinate for merocyanine dyes. In Journal of chemical physics. ISSN 0021-9606, 2017, vol. 146, no. 22.
CATALAN, Javier - REICHARDT, Christian. Solvation by glycerol at temperatures from 353 to 77 K: its solvatochromic characterization and use to block the molecular structure of conformationally flexible structures. In Journal of physical chemistry A. ISSN 1089-5639, 2017, vol. 121, no. 38, pp. 7114-7120.
PRAMOD, A. G. - RENUKA, G. G. - SHIVASHANKAR, K. - BOREGOWDA, P. - NADAF, Y. F. Solvent influence on the photophysical properties of 4-(2-oxo-2H-benzo[h]chromen-4-ylmethoxy)-benzaldehyde. In AIP conference proceedings : 2nd international conference on condensed matter and applied physics, Bikaner, 24th-25th November 2017. Melville : American institute of physics, 2018. ISBN 978-0-7354-1648-2, pp. [1-4].
MERA-ADASME, Raul - DOMINGUEZ, Moises. A computationally-derived model for the solvatochromism of p-phenolates with high predictive power. In Physical chemistry chemical physics. ISSN 1463-9076, 2018, vol. 20, no. 26, pp. 18127-18132.
LI, Kai - SU, Xi - WANG, Yixuan - TAO, Furong - CUI, Yuezhi - ZHANG, Huayong - LI, Tianduo. D-pi-a type barbituric derivatives : aggregation induced emission, mechanofluorochromic and solvatochromic properties. In Journal of luminescence. ISSN 0022-2313, 2018, vol. 203, pp. 50-58.
MERA-ADASME, Raul - CAROLI REZENDE, Marcos - DOMINGUEZ, Moises. On the physical-chemical nature of solvent polarizability and dipolarity. In Spectrochimica acta. Part A : molecular and biomolecular spectroscopy. ISSN 1386-1425, 2020, vol. 229, art. no. 118008, pp. 1-6.
|
|---|
