Synthesis, spectral behaviour and photophysics of donor-acceptor kind of chalcones: Excited state intramolecular charge transfer and fluorescence quenching studies

Mehboobali Pannipara; Abdullah M Asiri; Khalid A Alamry; Muhammad N Arshad; Samy A El-Daly

doi:10.1016/j.saa.2014.10.105

Synthesis, spectral behaviour and photophysics of donor-acceptor kind of chalcones: Excited state intramolecular charge transfer and fluorescence quenching studies

Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 5:136 Pt C:1893-902. doi: 10.1016/j.saa.2014.10.105. Epub 2014 Nov 1.

Authors

Mehboobali Pannipara¹, Abdullah M Asiri², Khalid A Alamry¹, Muhammad N Arshad², Samy A El-Daly³

Affiliations

¹ Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
² Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia; Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
³ Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia; Department of Chemistry, Faculty of Science, Tanta University, 31527 Tanta, Egypt. Electronic address: samyeldaly@yahoo.com.

PMID: 25467684
DOI: 10.1016/j.saa.2014.10.105

Abstract

The spectral and photophysical properties of two chalcones containing electron donating and accepting groups with intramolecular charge transfer characteristics were synthesized and characterized by (1)H NMR, (13)C NMR and X-ray crystallography. Both compounds show very strong solvent polarity dependent changes in their photophysical characteristics, namely, remarkable red shift in the emission spectra with increasing solvent polarity, large change in Stokes shift, significant reduction in the fluorescence quantum yield; indicating that the fluorescence states of these compounds are of intramolecular charge transfer (ICT) character. The solvent effect on the photophysical parameters such as singlet absorption, molar absorptivity, oscillator strength, dipole moment, fluorescence spectra, and fluorescence quantum yield of both compounds have been investigated comprehensively. For both dyes, Lippert-Mataga and Reichardt's correlations were used to estimate the difference between the excited and ground state dipole moments (Δμ). The interactions of dyes with colloidal silver nanoparticles (Ag NPs) were also studied in ethanol using steady state fluorescence quenching measurements. The fluorescence quenching data reveal that dynamic quenching and energy transfer play a major role in the fluorescence quenching of dyes by Ag NPs.

Keywords: Chalcones; Effect of solvent polarity; Photophysics; Silver nanoparticles.