Organic-inorganic manganese (II) halide hybrids based paper sensor for the fluorometric determination of pesticide ferbam

Abstract

Organic–inorganic metal halide hybrids, which consist of metal halide anions and organic cations, have been widely applied in the sensor design. Instead of general lead (high toxicity) and copper (I) (weak stability) halide hybrids, the low toxic and highly luminescent manganese (II) halide hybrids may be more promising for optical sensors. In this work, a paper sensor based on the organic-inorganic manganese (II) halide hybrids is fabricated as the first attempt. Three new highly luminescent and soluble manganese (II) halide hybrids MnBr4(TPA)2, MnBr4(TEA)2 and MnCl4(btmdme)2 are prepared, and their quantum yields are 89.23%, 78.86% and 71.28%, respectively. The hybrids are dispersed uniformly and immoblized on the wax-based paper. The as-fabricated sensor is used for the fluorometric determination of pesticide ferbam, and the limit of detection is calculated to be 0.06 ppm, which is even lower than the maximum permissible concentration in EU pesticides database. Moreover, the practical application of ferbam assay for apple and pear samples is described with satisfactory recoveries (91.88–101.32%). The mechanism of ferbam detection is investigated in detail, and tentatively explained by the interaction between the manganese in MnBr4(TPA)2 and the sulfur in ferbam together with the inner filter effect (IFE).