Histidine is a neurotransmitter and an essential amino acid for human growth, deficiency can cause impaired kidney function. Detection in biological fluids is therefore of interest.

Researchers around Lin Pu, Sichuan University, Chengdu, China, have demonstrated that terpyridine-CuCl₂ gives a fluorescence enhancement of more than 1000-fold when the aqueous solution of this complex was treated with L-histidine. The team used fluorescence, UV absorption, cyclic voltammetry, and mass spectrometry to demonstrate that the mechanism involves the swapping out of the chlorine atoms from the complex and their replacement with the histidine present in an aqueous sample.

• A Simple and Efficient Fluorescent Sensor for Histidine,
  Zeng Huang, Jiao Du, Jing Zhang, Xiao-Qi Yu, Lin Pu,
  Chem. Commun. 2012.
  DOI: 10.1039/C2CC17156B