Calix[4]pyrrole–TCBQ assembly: a signal magnifier of TCBQ for colorimetric determining amino acids and amines

The interaction and colorimetric sensing properties of the calix[4]pyrrole–TCBQ charge-transfer complex with amino acids and amines in CHCl3/EtOH/H2O were investigated using UV/vis spectroscopic techniques. The obvious spectral and visual changes of the complex solution in the presence of basic amino acids (namely, lysine, arginine, and histidine) and aliphatic amines were observed, and the calix[4]pyrrole–TCBQ supramolecular assembly, like a ‘signal magnifier’, markedly improves sensing sensitivity and selectivity of TCBQ for amino acids and amines.