Thipperudrappa J, Raghavendra U P, Basanagouda Mahantesha
Department of Physics, B.N.M. Institute of Technology, Bangalore 560 070, India.
Department of Physics, Bangalore Institute of Technology, Bangalore 560 004, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 5;136 Pt C:1475-83. doi: 10.1016/j.saa.2014.10.039. Epub 2014 Oct 22.
The absorption and fluorescence characteristics of biologically active coumarin derivatives 4-p-tolyloxymethyl-benzo[h]coumarin (4PTMBC) and 1-(4-iodo phenoxymethyl)-benzo[f]coumarin (1IPMBC) are studied at room temperature in a series of organic solvents and 1,4-dioxane - acetonitrile solvent mixture. The effect of pure solvents on the spectral properties are analyzed using Lippert-Mataga polarity function, Reichardt's microscopic solvent polarity parameter, Kamlet's and Catalan's multiple linear regression approaches. Both general solute - solvent interactions and hydrogen bonding interactions are operative in these systems. However, the contribution of hydrogen bonding interactions is less compared to general solute-solvent interactions. The solvatochromic correlations are used to estimate excited state dipole moment using experimentally determined ground state dipole moment. The bathochromic shift of the emission spectra and the increase in excited state dipole moment indicate the intramolecular charge transfer (ICT) character in the emitting singlet state. The solvation studies in 1,4-dioxane - acetonitrile solvent mixture suggest that these dyes are preferentially solvated by 1,4-dioxane.
在室温下，于一系列有机溶剂以及1,4 - 二氧六环 - 乙腈混合溶剂中研究了具有生物活性的香豆素衍生物4 - 对甲苯氧基甲基 - 苯并[h]香豆素（4PTMBC）和1 -（4 - 碘苯氧基甲基） - 苯并[f]香豆素（1IPMBC）的吸收和荧光特性。使用Lippert - Mataga极性函数、Reichardt微观溶剂极性参数、Kamlet和Catalan的多元线性回归方法分析了纯溶剂对光谱性质的影响。在这些体系中，一般的溶质 - 溶剂相互作用和氢键相互作用都起作用。然而，与一般的溶质 - 溶剂相互作用相比，氢键相互作用的贡献较小。利用溶剂化显色相关性，通过实验测定的基态偶极矩来估算激发态偶极矩。发射光谱的红移和激发态偶极矩的增加表明发射单重态具有分子内电荷转移（ICT）特性。在1,4 - 二氧六环 - 乙腈混合溶剂中的溶剂化研究表明，这些染料优先被1,4 - 二氧六环溶剂化。
