Department of Physics, B.N.M. Institute of Technology, Bangalore 560 070, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 May;108:288-94. doi: 10.1016/j.saa.2013.01.084. Epub 2013 Feb 16.
The absorption and fluorescence spectra of 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoro methyl)-2H-pyrano[2,3-b][1,8]naphthyridin-2-one (LD-489) and 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) have been recorded at room temperature in different solvents and 1,4-dioxane-acetonitrile solvent mixtures. The UV-Visible absorption spectra are less sensitive to solvent polarity than the corresponding fluorescence spectra in both the dyes which show pronounced solvatochromic effect. The effects of solvents upon the spectral properties are analyzed using Lippert-Mataga polarity function, Richardts microscopic solvent polarity parameter and Catalán's multiple linear regression approach. Both general solute-solvent interactions and specific interactions are operative in these systems. The solvatochromic correlations are used to estimate excited state dipole moments using experimentally determined ground state dipole moments. The excited state dipole moment for both the dyes are found to be larger than their corresponding ground state dipole moment and is interpreted based on their resonance structures.
室温下记录了 6,7,8,9-四氢-6,8,9-三甲基-4-(三氟甲基)-2H-吡喃并[2,3-b][1,8]萘啶-2-酮（LD-489）和 1,2,3,8-四氢-1,2,3,3,8-五甲基-5-(三氟甲基)-7H-吡咯并[3,2-g]喹啉-7-酮（LD-473）在不同溶剂和 1,4-二恶烷-乙腈溶剂混合物中的吸收和荧光光谱。在这两种染料中，紫外-可见吸收光谱对溶剂极性的敏感性低于相应的荧光光谱，它们表现出明显的溶剂化显色效应。使用 Lippert-Mataga 极性函数、Richardts 微观溶剂极性参数和 Catalán 的多元线性回归方法分析了溶剂对光谱性质的影响。在这些体系中，既有一般的溶质-溶剂相互作用，也有特定的相互作用。利用溶剂化显色相关关系，根据实验测定的基态偶极矩估算激发态偶极矩。发现两种染料的激发态偶极矩都大于其相应的基态偶极矩，并根据其共振结构进行了解释。
