Department of Chemistry, Annamalai University, Annamalai Nagar 608 002 Tamilnadu, India.
J Fluoresc. 2011 Jul;21(4):1485-97. doi: 10.1007/s10895-011-0835-1. Epub 2011 Feb 1.
Spectral characteristics of 1-(2,4-diamino phenylazo) naphthalene (FBRR, fat brown RR) and 4-aminoazobenzene (AAB) have been studied in various solvents, varying hydrogen ion concentrations and in β-cyclodextrin (β-CD). The inclusion complex of FBRR and AAB with β-CD were analysed by UV-visible, fluorometry and CAche-DFT methods. Solvent study reveals that only azo tautomer is present in both compounds and the large red shifted absorption and emission maxima of FBRR indicate naphthalene ring effectively increases the π-π* transition. Unusual red shift is observed in acid solutions suggests azonium-ammonium tautomer is present in both molecules. In β-CD solutions, the large hypsochromic shift is observed in S(0) and S(1) states indicates ortho amino group of FBRR molecule is entrapped in the β-CD cavity and the large bathochromic shift for AAB in the S(1) state indicates 1:1 inclusion complex is formed.
1-(2,4-二氨基苯基偶氮)萘(FBRR，棕褐色 RR)和 4-氨基偶氮苯(AAB)的光谱特性在各种溶剂、不同氢离子浓度和β-环糊精(β-CD)中进行了研究。采用紫外-可见分光光度法、荧光法和 CAche-DFT 方法对 FBRR 和 AAB 与β-CD 的包合配合物进行了分析。溶剂研究表明，两种化合物中都只存在偶氮互变异构体，FBRR 的较大红移吸收和发射最大值表明萘环有效地增加了π-π*跃迁。在酸性溶液中观察到的异常红移表明两种分子中都存在偶氮翁-铵互变异构体。在β-CD 溶液中，S(0)和 S(1)态的较大蓝移表明 FBRR 分子的邻氨基在β-CD 腔中被包合，而 AAB 在 S(1)态的较大红移表明形成了 1:1 的包合配合物。
