Effect of solvent on absorption and emission spectra of 2,2′-Bipyridine and its inclusion complexinto β-cyclodextrin: DFT and TD-DFT study

Abstract

In this work, a theoretical study has been conducted using DFT and TD-DFT methods on 2,2′-Bpy and 2,2′-Bpy@β-CD inclusion complex (1:1) in different solvent. The properties of 2,2′-Bpy and 2,2′-Bpy@β-CD inclusion complex, including UV–Vis spectra, oscillator strength (f), transition energy , gap energy (EHOMO-ELUMO) are calculated to give more insight about absorption and emission properties of the studied molecules. The TD-DFT/B3LYP/6–31 (d) investigation gives that the major transition on UV–visible spectra of free 2,2′-Bpy is occurred between π → π* and it is greatly affected by the polarity of the solvent. The presence of β-CD modify largely spectroscopic properties, in addition to π → π* transition the n → π* one is occurred and the micro environment of 2,2′-Bpy is largely changed. Finally, NBO, NCI and MEP analysis suggest that non covalent interactions such as hydrogen bonds and Van der Waals interactions influence greatly absorption and emission spectra of 2,2′-Byp upon 1:1 complex formation into β-CD.