Y-shaped ferrocene/non-ferrocene conjugated quinoxalines for colorimetric and fluorimetric detection of picric acid.

Abstract

New Y-shaped ferrocene and non-ferrocene conjugated quinoxaline derivatives {[R-(CH)2-N=CH-)2C10H4], R=C5H5-Fe-C5H5 (1) and R=C6H4-OCH3 (2)} have been synthesized and characterized using analytical and spectroscopic techniques. The thermal stability of the compounds 1 and 2 were examined by thermogravimetric analysis (TGA), both were stable up to 250°C. The optical properties were studied using UV-Visible and fluorescence spectroscopic methods and Y-shaped ferrocene appended quinoxaline derivative 1 show a weak emission due to the quenching nature of ferrocene. The compound 2 shows enhanced fluorescence intensity in their aggregation state due to Restricted Intramolecular Rotation (RIR). Hence, the compound 2 have further utilized for the detection of picric acid (PA) by fluorimetric method and the detection limit of 1.37×10-6M was obtained. Further, paper sensor was made using compound 2 which resulted in the instant 'naked eye' response for trace detection of picric acid. Consequently, the compound 2 acts as a colorimetric sensor and can be used as a new probe for the detection of nitro aromatic explosives.