Activity of N–H in phenothiazine derivatives: synthesis and applications in fluoride ions sensing and electrochromism

Abstract

A series of phenothiazine derivatives containing N–H, 3a, 3b, 3c and a N-substituted phenothiazine derivative, 3d were synthesized. These phenothiazine derivatives exhibited good air/moisture stability and excellent fluorescence properties. They showed excellent chromic behaviour in response to multiple external stimuli, especially fluoride ions and the application of electric voltages. The addition of fluoride ions to these phenothiazine derivatives induced a rapid change in the emission colour from blue to yellow, accompanied by significant changes in the emission intensity. This response was shown to be highly selective to fluoride ions. Films deposited from solutions of a blend of 3a and polycaprolactone also demonstrated a good ratiometric sensing ability for fluoride ions. Electrochromic devices (ECDs) fabricated from these composites exhibited reversible changes in color that depended on the applied voltage.