title: Photophysical and Photoprototropic Characteristics of 2-Aminobenzothiazole in β-Cyclodextrin Medium.
abstract: The formation of stable inclusion complexes between neutral and monocationic species of 2-aminobenzothiazole (2ABT) with β-CDx is observed with significant enhancement in absorbance and fluorescence intensity. The stoichiometry of the 2ABT and 2ABTH⊕with β-CDx is found to be 1:1 at pH 6.8 and 1.1. Their binding constant values for neutral and monocationic species are found to be 1239.3 and 1259.2 M-1, respectively. Lifetime analysis, FT-IR spectral and SEM image analysis strongly supports the formation of the inclusion complex between 2ABT and β-CDx. Photoprototropic study shows that there is no remarkable difference in the pKaand pKa* in aqueous and β-CDx media, which is rules out the formation of the inclusion complex with -NH2group of 2ABT inside the cavity of β-CDx i.e., the -NH2group of 2ABT is in aqueous environment. Based on stoichiometry, binding constant and acidity constant values, the structure of the 1:1 complex is proposed.
authors.affiliation: Department of Chemistry, S.K.P Engineering College, Tiruvannamalai, 606 611, Tamil Nadu, India. rajmohanau@gmail.com.
authors.forename: Rajaram
authors.initials: R
authors.lastname: Rajamohan
authors.affiliation: Chemistry Section, FEAT, Annamalai University, Annamalainagar, 608 002, Tamil Nadu, India.
authors.forename: Sundarrajulu
authors.initials: S
authors.lastname: Kothai Nayaki
authors.affiliation: Centre for Research, Kalasalingam University, Krishnankoil, 626 126, Tamil Nadu, India.
authors.forename: Meenakshisundaram
authors.initials: M
authors.lastname: Swaminathan
keywords: 2-aminobenzothiazole; Cyclodextrin; Solid complex; pK a and pK a*