A comprehensive spectroscopic and computational investigation of intramolecular proton transfer in the excited states of 2-(2′-hydroxyphenyl) benzoxazole and its derivatives

• Published in: Journal of luminescence 2014-02, Vol.146, p.527-538
• Main Authors: Padalkar, Vikas S., Ramasami, Ponnadurai, Sekar, Nagaiyan
• Format: Article
• Language: English
• Subjects: Acceptors (electronic); Benzoxazole; Computation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Derivatives; Deviation; Electronics; ESIPT; Exact sciences and technology; Excitation spectra; Fluorescence; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Orbitals; Photoluminescence; Physics; Solvatochromism; Spectroscopy; TD-DFT
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2013.09.007

The excited-state intramolecular proton transfer (ESIPT) fluorescence of the 2-(2′ hydroxyphenyl) benzoxazole (HBO) and its derivatives with NO2 as electron acceptor and NH2 as electron donor at the 4 and 5 position of benzoxazole ring was studied by spectroscopic and computational methods. The changes in the electronic transition, energy levels, and orbital diagrams of the HBO derivatives were investigated using the DFT computations and they were correlated with the experimental spectral emission. The benzoxazole derivatives are fluorescent under UV-light in solution. Photophysical properties of the compounds were also studied in solvents of different polarities. Experimental absorption and emission wavelengths are in agreement with those computed with a deviation ranging between 0 and 50%. The computational methods have been useful for molecular understanding of the transitions responsible for the fluorescent spectra. •Experimental photophysical properties of 2-substituted benzoxazoles in different solvents have been studied and compared with the computational data.•Compounds show dual emission due to ESIPT process and was supported by DFT and TD-DFT computations.•Experimental results and computational results are in good agreements.