A combined spectroscopic and TDDFT investigation of the solute‐solvent interactions of two coumarin derivatives

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.

Experimental and theoretical study on structure and spectroscopic properties of 2‐bromo‐3‐N‐(N′,N′‐dimethylformamidino) benzanthrone

“…Among different theoretical approaches semi‐empirical PM6 method is widely used for the optimization of molecular structures . Nowadays the DFT becomes more and more popular in the quantum‐chemical calculations for investigating and predicting electronic properties of organic chromophores in both the ground and the excited states . In present work semi‐empirical PM6 method was applied for determination of geometric structure and electron density distribution.…”

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“…These side effects occur when the consumption is more than dietary level and when the person in under other medications. The biological potential of other versatile molecules like Coumarin & Pyrimidine acting as CNS depressants, antimicrobial agents, natural product extraction and its biological potential & also our previous group contribution [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66] .…”