Inducing the distinctly different fluorescence properties of a tetraphenylethene (TPE) derivative modified lanthanide nanowire upon the addition of a pair of cis- and trans-isomers of fatty acids

Abstract

A simple layer-by-layer approach has been developed to introduce a 3,5-dicarboxylphenoxy decorated tetraphenylethene derivative (denoted as TPE-2COOH) into a lanthanide nanowire. Interestingly, the aggregation-induced emission (AIE) was turned on by loading the negative TPE-2COOH on the positive surface of the nanowire via electrostatic interactions. More excitingly, these synthesized composite nanowires exhibit significantly different fluorescence properties in the presence of a pair of cis- and trans-isomers of fatty acids (oleic acid and elaidic acid). The obvious emission peak (382 nm) upon the addition of oleic acid (cis-configuration) was observed, which was consistent with that of the frozen diluted TPE-2COOH solution (1.95 × 10⁻¹⁰ mol L⁻¹), demonstrating the occurrence of the monomer emission of TPE-2COOH. When the oleic acid with a special cis-configuration got close to the nanowire, it substituted some TPE-2COOH and arranged as cages on the surface to isolate the TPE-2COOH molecule, leading to the monomer emission. Different from such monomer emission induced by oleic acid, an attenuated aggregate emission was detected by the addition of its trans isomer elaidic acid, because it is almost impossible for the elaidic acid with a linear structure to form the cage-like shape on the surface during the substitution process. It was found for the first time that the fluorescence of such a TPE-based material can be controlled by the configuration of isomers. This discovery may provide a facile strategy to design and synthesize more promising candidates for TPE-based fluorescent sensors.