Search

A distinctive water soluble chemosensor based on naphthalene-glycine conjugate has been designed. The synthesized molecule is highly selective and sensitive towards detection of iodide ion in aqueous solution. The probe exhibits a color change from colorless to pale pink that can be detected by naked eye which is a simple and cost effective detection method. Further, addition of iodide ion led to the complete diminution of the fluorescence intensity of ligand 1 . Under optimal conditions, its response was linearly proportional to the concentration of I − ion (range from 6.25 × 10 −6 to 3.12 × 10 −5  mol L −1 ) with a detection limit of 30 nM. Based on the 1 H NMR titration, ESI–MS data and Job’s plot, the probable binding mode of this receptor with iodide ion has also been postulated and binding ratio of ligand to I − ion is found to be 2:1. This result is also supported by the theoretical calculation using DFT method. The molecular structure of 1 revealed the existence of different intermolecular C H/O and O H/N hydrogen bonds which led to the formation of a zig - zag linear 1D tape. Furthermore, the selectivity and sensitivity of the present probe towards iodide ion is also preserved on test kits made of cellulose bound filter paper and on supported solid silica. [ABSTRACT FROM AUTHOR]

Reaction of [Cp∗CoCl]2 (Cp∗ = η5-C5Me5) with [LiBH4·THF] in toluene at −70 °C, followed by thermolysis with 2-mercaptobenzothiazole (C7H5NS2) in boiling toluene led to the isolation of a range of cobaltaborane clusters, [(Cp∗Co)2B7H6OMe], 1; [(Cp∗Co)3B8H7R], 2a, b (2a: R = H; 2b: R = Me); [(Cp∗Co)3B8H8S], 3 and [(Cp∗Co)2B4H4RR′], 4a–d (4a: R, R′ = H; 4b: R = Me, R′ = H; 4c: R = H, R′ = Me and 4d: R, R′ = Me). In parallel to the formation of compounds 1–4, the reaction also yielded known [(Cp∗Co)3B4H4] in good yield. Compound 1 may be considered as 9-vertex hypoelectronic cluster with C1 symmetry, where cobalt atoms occupy the degree 5 vertices. All the dicobaltaboranes 4a–d contains two μ3-H protons and found to be very reactive. As a result, one of them (4a) when reacted with Fe2(CO)9 and sulfur powder yielded, almost immediately, [(Cp∗Co)2B4H5SFe3(CO)9], 5 and [(Cp∗Co)2B3H3(μ-CO)Fe(CO)3], 6. All the new compounds have been characterized in solution by mass, 1H, 11B, 13C NMR spectroscopy and elemental analysis. The structural types were unequivocally established by X-ray crystallographic analysis of compounds 1–6. Density functional theory (DFT) calculations on the model compounds 1′ and 2′ (1′, and 2′ are the Cp analog of 1, and 2a respectively, Cp = C5H5) yield geometries in agreement with the structure determinations. The existence of large HOMO–LUMO gap of these molecules rationalizes the isocloso description for 2a. Bonding patterns in the structure have been analyzed on the grounds of DFT calculations. [ABSTRACT FROM AUTHOR]