The optical and colorimetric sensing properties of H2L1–H2L3 for anions were investigated by the naked eye and UV-Vis and fluorescence spectroscopy. The spectral change of H2L1–H2L3 is due to the anion induced deprotonation and hence an increase in charge density and rigidity of the receptor molecule. The anion sensing abilities of the receptors toward halide anions were also monitored by electrochemical techniques.

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This paper reports results of cooperativity in lithium bonding on the strength of halogen bonding and tetrel bonding in complexes pairing CF3Cl and SiF3Cl with (LiCN)n complexes, where n varies from 1 to 5. Molecular geometries and stabilization energies of title complexes are calculated at the MP2 level with 6-311++G(d,p) basis set. Cooperative effects are found in terms of structural and energetic properties when lithium, halogen, and tetrel bonds are present in these complexes simultaneously. Our results reveal that strength of halogen and tetrel bondings are enhanced due to cooperativity of Li···N interactions in lithium bonded complexes. Good linear correlations between cooperativity parameters and electronic properties of complexes were established in the present study.

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The optical and colorimetric properties of a new chemosensor 4-((2,4-dichlorophenyl) diazenyl)-2-(3-hydroxypropylimino)methyl)phenol (L) for cyanide ions were investigated by the naked-eye detection and UVevis spectroscopy. This receptor reveals visual changes toward CN À anions in aqueous media. No significant color changes were observed upon the addition of any other anions. The cyanide recognition properties of the receptor through proton-transfer were monitored by UVevis titration and 1 H NMR spectroscopy. The binding constant (K a ) and stoichiometry of the formed hosteguest complex were calculated by the BenesieHildebrand (BeH) plot and Job's plot method, respectively. The detection limit of the probe towards CN À was 1.03 Â 10 À6 mol L À1 , which is lower than the maximum value of cyanide (1.9 Â 10 À6 mol L À1 ) permitted by the World Health Organization in drinking water. Thus, this chemosensor was sensitive enough to detect cyanide in aqueous solutions. 1 H NMR experiments were conducted to investigate the nature of interaction between the receptor and CN À anions. Notably, the designed sensor can be applied for the rapid detection of cyanide anions in the basic pH range and also under physiological conditions, for practical purposes for a long duration. The sensing behavior of the receptor was further emphasized by computational studies. Quantum-chemical calculations and molecular studies via Density Functional Theory (DFT) were carried out to supplement the experimental results.