Azonium-Ammonium Tautomerism and Inclusion Complexation of 1-(2,4-diamino phenylazo) Naphthalene and 4-aminoazobenzene

作者：Venkatesh G; Prabhu A Antony Muthu; Rajendiran N^*

来源：Journal of Fluorescence, 2011, 21(4): 1485-1497.

DOI：10.1007/s10895-011-0835-1

• Fat brown RR
• Tautomerism
• beta-cyclodextrin
• Inclusion complex
• Solvent
• pH effect

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 beta-cyclodextrin (beta-CD). The inclusion complex of FBRR and AAB with beta-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 pi-pi* transition. Unusual red shift is observed in acid solutions suggests azonium-ammonium tautomer is present in both molecules. In beta-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 beta-CD cavity and the large bathochromic shift for AAB in the S(1) state indicates 1:1 inclusion complex is formed.

• 出版日期2011-7