Colorimetric detection of histidine in aqueous solution by Ni2+ complex of a thiazolylazo dye based on indicator displacement mechanism
A colorimetric naked-eye chemosensor for histidine (His) was established by mixing a thiazolylazo dye and Ni2+ in a 1:1 M ratio (TAMSMB-Ni2+). Due to the interaction of Ni2+ with His, TAMSMB was regenerated upon the addition of His to TAMSMB-Ni2+ to lead a significant hypsochromic shift in absorption spectra accompanied by a visual color change from red to yellow which can be directly observed by the naked eye. On the other hands, other amino acids did not trigger any significant changes in absorption properties and solution color. Moreover, it exhibited the selective recognition of His without obvious interference from other amino acids. Thus, TAMSMB-Ni2+ can act as a simple and efficient colorimetric chemosensor for His with sensitivity and selectivity in aqueous solution.