A Schiff base colorimetric chemosensor for CN^‐ ion and its dioxidomolybdenum (VI) complexes: Evaluation of structural aspects and optoelectronic properties

Abstract

Six new cis‐dioxidomolybdenum(VI) complexes featured with a tridentate ONO donor Schiff base derived from salicylidene‐2‐aminophenolato backbone have been synthesised and characterised by elemental analysis, spectroscopic techniques (like IR, UV‐vis and 1H‐NMR) and cyclic voltammetry. Suitable single crystals of the parent complex [MoO2L(MeOH)]2·H2O (1) was obtained by the slow evaporation of the mother liquor, whereas the crystals of the complexes 2‐6 were grown in coordinating solvents like ethanol, DMF, DMSO etc. and were characterised by single crystal X‐ray diffraction as monomers stabilised by the solvent molecules used for the recrystallization purpose. The structures of the complexes were further quantified using Hirshfeld surface analysis. The Schiff base acts as a colorimetric chemosensor for CN‐ ions in DMSO solution. The receptor‐CN‐ ion interaction and the sensing mechanism of the chemosensor were verified by colorimetric, UV‐vis, 1H‐NMR and FT‐IR spectroscopic studies. Hydroxyl moiety present in the receptor function as the binding site for cyanide ion thereby leading to its optical discrimination in presence of other anions by producing a visible colour change from colourless to yellow. Therefore the Schiff base sensor portrays estimable selectivity and sensitivity towards CN‐ ion. Additionally the Schiff base as well as the molybdenum complexes exhibit good third order non‐linear optical properties and optical power limiting when analysed by the Z‐scan technique.

Schiff bases as analytical tools: synthesis, chemo-sensor, and computational studies of 2-aminophenol Schiff bases

“…39 A variety of sensing mechanisms have been reported for chemo-sensors designed for Cu 2+ , Zn 2+ , and Ni 2+ . [40][41][42][43][44] There have been reports of Schiff bases of 2-aminophenols as chemosensors due to their ability to coordinate to some metal ions in solutions, [45][46][47][48][49] but none of them have been used in the evaluation of 2-aminophenol with salicylaldehyde MJ 1 and 5-bromosalicylaldehyde MJ 2 as a chemo-sensor in the detection of Cu 2+ and Zn 2+ in solution.…”

Revisiting salicylidene-based anion receptors

“…Several chromogenic cyanide (CN − ) sensors based on the nucleophilic additions of CN − to –N CH– or O CR– bonds are reported in the literature. 13 Further, numerous fluoride chemodosimeter (reactive sensors) are also known in the literature. 14 This suggests that the reaction between an anion and a Schiff base cannot be ruled out, and detailed experimental investigations are necessary to come to a definite conclusion.…”