Spectroscopic and TDDFT investigation of highly selective fluoride sensors by substituted acyl hydrazones

Athira M John; Jemini Jose; Renjith Thomas; Karukappallil J Thomas; Sreeja P Balakrishnan

doi:10.1016/j.saa.2020.118329

Spectroscopic and TDDFT investigation of highly selective fluoride sensors by substituted acyl hydrazones

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Aug 5:236:118329. doi: 10.1016/j.saa.2020.118329. Epub 2020 Apr 3.

Authors

Athira M John¹, Jemini Jose¹, Renjith Thomas², Karukappallil J Thomas¹, Sreeja P Balakrishnan³

Affiliations

¹ Department of Chemistry, CHRIST (Deemed to be University), Bangalore, Karnataka 560029, India.
² Department of Chemistry, St. Berchmans College (Autonomous), Changanassery, Kerala 686101, India.
³ Department of Chemistry, CHRIST (Deemed to be University), Bangalore, Karnataka 560029, India. Electronic address: sreeja.pb@christuniversity.in.

PMID: 32299039
DOI: 10.1016/j.saa.2020.118329

Abstract

In this work, we report the synthesis of two receptors for fluoride ions based on acyl hydrazone, such as N'-[(1Z)-1-(4-fluorophenyl)ethylidene]benzohydrazide (R1) and N'-[(1Z)-1-(2-hydroxyphenyl)ethylidene]benzohydrazide (R2). The receptors R1 and R2 were synthesized from the corresponding ketones and benzoic acid hydrazide and characterized spectroscopically by UV-visible, IR and ¹HNMR techniques. The response of R1 and R2 towards different anions was studied colourimetrically in acetonitrile. The receptors exhibited a specific response towards fluoride ions. Further studies of 1:1 composition of receptors, R1/R2:fluoride ions by different spectroscopic techniques such as UV-Visible, IR and ¹HNMR spectroscopy indicated the participation of -NH proton of the receptors in the sensing action through the hydrogen bonding. To understand the mechanism, Time-Dependent Density Functional Theory (TD-DFT) studies were done using the CAM-B3LYP/6311G++ (3df,2p) with Grimme's D3BJ empirical dispersion basis set. The studies supported the role of hydrogen bonding interaction of -NH and-OH protons of the receptors with the fluoride ions.

Keywords: Acyl hydrazones; Anion recognition; Chemosensors; Fluoride sensing; Theory (TDDFT); Time dependent density functional.