Synthesis of a highly fluorescent N,N-dimethyl benzylamine–palladium(II) curcuminate complex and its application for determination of trace amounts of water in organic solvents

Abstract

In this work a new highly fluorescent N,N-dimethyl benzylamine–palladium(II) yu complex was synthesized by the reaction of [Pd2{(C,N–C6H4CH2N(CH3)2}2(μ-OAc)]2] with curcumin. The structure of the synthesized complex was characterized using Fourier transform infra-red (FT-IR) spectroscopy, 1H nuclear magnetic resonance spectroscopy, and elemental analysis. Fluorescence quantum yield (ΦF) values of the synthesized complex in dimethyl sulfoxide (DMSO), acetonitrile, ethanol, and methanol were 0.160, 0.104, 0.068, and 0.061, respectively. The fluorescence signal of the complex in the organic solvents was very sensitive to the water content of the organic solvent. The quenching effect of water was used to determine trace amounts of water in the heteroatom-containing organic solvents (ethanol, methanol, acetonitrile) and redox-active solvents (DMSO). The linear ranges for determination of water (v/v %) in ethanol, DMSO and acetonitrile were found to be 0.03–14.5, 0.08–13.8, and 0.07–18.8, respectively. Two linear ranges were found for determination of water (v/v %) in methanol (0.1–1.2 and 4.7–25.0). Detection limit (DL) values were calculated to be 0.001, 0.05, 0.004, and 0.01 (v/v %) in ethanol, methanol, acetonitrile, and DMSO, respectively. The proposed method overcomes the problems of the standard Karl Fischer method for determination of water in DMSO. In addition, it gave the best DL value for determination of water in ethanol compared with all published papers to date.