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

Kumar, Gaurav, Solanki, Pratik, Nazish, Mohd, Neogi, Subhadip, Kureshy, Rukhsana I., Khan, Noor-ul H.
Journal of catalysis 2019 v.371 pp. 298-304
Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, adverse effects, catalytic activity, chemical bonding, coordination polymers, dyes, light, nuclear magnetic resonance spectroscopy, photocatalysts, scanning electron microscopy, tertiary amines, thermogravimetry, toxicity, transmission electron microscopy, zirconium
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.