A composite nanosensing array with two response channels for trinitrobenzoic acid optical test.

Abstract

In this paper, the authors reported a composite platform for the optical sensing of 2,4,6-trinitrobenzoic acid (TBA). This composite sensing platform consisted of luminescent rare earth MOF and a rhodamine-derived sensing probe. Its composite structure was confirmed by means of XRD, IR, TGA and photophysical measurement. It was found that there were two emission components in this sensing platform, which were rhodamine emission component and Eu(III) emission component, respectively. The rhodamine emission was enhanced with increasing TBA concentration, while the Eu(III) emission component was quenched by increasing TBA concentration, showing self-calibrated sensing signals for ratiometric fluorescent sensing. In addition, rhodamine absorption in visible region was increased with increasing TBA concentration, showing colorimetric sensing. The above mentioned two sensing channels both showed high selectivity and linear response towards TBA with LOD of 2.4μM. By comparing emission lifetime under various TBA concentrations, the sensing mechanism was convinced as the combination of rhodamine emission turn on effect initiated by TBA -released protons and Eu(III) emission turn off effect caused by an ET (energy transfer) procedure from EuBTC to TBA. This sensing platform showed naked eye sensing and two sensing channels with linear response and high selectivity.