Electrochromic lutetium phthalocyanine films for in situ detection of NADH

A simple and sensitive method for the detection of NADH on a glass substrate modified with spin coated electrochromic [(C6H13S)8Pc]2Lu is presented. The modification of a [(C6H13S)8Pc]2Lu sensing layer was achieved chemically. The functionalized layer shows an efficient activity towards the NADH at conc. as low as 1 × 10−5 M. The in situ UV–Vis and Raman measurements were carried out to study the interaction of oxidized films with NADH. The electrochromic behaviour of [(C6H13S)8Pc]2Lu thin films was examined in detail under various conditions. The spin coated films deposited on glass substrate were chemically oxidized and were found to change the colour. The oxidized films were believed to be reduced to its natural form on interaction with NADH. The colour of the film changed from green to brownish-purple after interaction with NADH. Reversible electrochromism was observed, leading reusable sensor film. The transformation of the oxidised phthalocyanine films into neutral form was monitored by both in situ UV–Vis and Raman techniques.

► Electrochromic behaviour of [(C6H13S)8Pc]2Lu thin films was examined.
► Oxidized film reduces to its natural form on interaction with NADH.
► Reversible electrochromism was observed, leading reusable optical sensor.