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A Combined Spectroscopic and TDDFT Investigation of the Solute-Solvent Interactions of Two Coumarin Derivatives

Shivraj, Anup Thomas, B Siddlingeshwar, Sharanabasappa B Patil

Luminescence. 2017 Nov;32(7):1328-1338.

PMID: 28581184

Abstract:

The UV/Vis absorption and fluorescence characteristics of 3-cyano-7-hydroxycoumarin [CHC] and 7-amino-4-methyl-3-coumarinylacetic acid [AMCA-H] were studied at room temperature in several neat solvents and binary solvent mixtures of 1,4-dioxane/acetonitrile. The effects of solvent on the spectral properties are analyzed using single and multi-parameter solvent polarity scales. Both general solute/solvent interactions and hydrogen bond interactions are operative in these systems. The solvation of CHC and AMCA-H dyes in 1,4-dioxane/acetonitrile solvent mixtures has been studied. The solutes CHC and AMCA-H are preferentially solvated by acetonitrile and a synergistic effect is observed for both molecules in dioxane/acetonitrile solvent mixtures. In addition, using the solvatochromic method the ground- and the excited-state dipole moments of both the dyes were calculated. The ground- and excited-state dipole moments, absorption and emission maxima and HOMO-LUMO gap were also estimated theoretically using B3LYP/6-311+ G (d,p) level of theory in the gaseous phase, dioxane and acetonitrile solvents. Furthermore, changes in dipole moment values were also calculated using the variation of Stokes shift with the molecular-microscopic empirical solvent polarity parameter ( ETN). The observed excited-state dipole moments are larger than their ground-state counterparts, indicating a substantial redistribution of the electron densities in a more dipolar excited state for both coumarins investigated.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP106562327 7-Amino-4-methyl-3-coumarinylacetic acid 7-Amino-4-methyl-3-coumarinylacetic acid 106562-32-7 Price
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