Covalently hooked EOSIN-Y in a Zr(IV) framework as visible-light mediated, heterogeneous photocatalyst for efficient C[sbnd]H functionalization of tertiary amines

Abstract

Herein, we report the synthesis of a novel heterogeneous photo-catalyst by utilizing post-synthetic modification of an amine functionalized Zr(IV) metal-organic framework (UiO-66-NH2) through covalent hooking of EOSIN-Y via dehydrating coupling. The characterization of the catalyst was accomplished by FT-IR, XRD, BET surface analysis, TGA, as well as TEM, SEM, XPS, DRS-UV–visible, and NMR spectroscopy, confirming successful covalent linking of EOSIN-Y with the pendent NH2 functionality in the framework. That post-modified EY@UiO-66-NH2 acts as simple and green visible light mediated photo-catalyst for the CH activation of tertiary amines with excellent yields. Importantly, the activity of dye incorporated heterogeneous photo-catalyst is found superior to that for the homogeneous photo-catalyst EOSIN-Y. Thus, separation difficulty of homogeneous catalysis, as well as the environmental adverse effects of toxic EOSIN-Y can be excluded by developing such photo-catalyst. Moreover, EY@UiO-66-NH2 catalyst could be consistently recycled up to 10 cycles, without any significant loss in activity. Based on literature report and experimental findings, we also propose a plausible mechanism for the reaction.