CsCu2I3 Nanoparticles Incorporated within a Mesoporous Metal-Organic Porphyrin Framework as a Catalyst for One-Pot Click Cycloaddition and Oxidation/Knoevenagel Tandem Reaction

Abstract

[EN] Metal-organic frameworks (MOFs) and metal halide perovskites are currently under much investigation due to their unique properties and applications. Herein, an innovative strategy has been developed combining an iron-porphyrin MOF, PCN-222(Fe), and an in situ-grown CsCu2I3 nontoxic lead-free halide perovskite based on an earth-abundant metal that becomes incorporated within the MOF channels [CsCu2I3@PCN-222(Fe)]. Encapsulation was designed to decrease and control the particle size and increase the stability of CsCu2I3. The hybrid materials were characterized by various techniques including FE-SEM, elemental mapping and line scanning EDX, TEM, PXRD, UV-Vis DRS, BET surface area, XPS, and photoemission measurements. Hybrid CsCu2I3@PCN-222(Fe) materials were examined as heterogeneous multifunctional (photo)catalysts for copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) and one-pot selective photo-oxidation/Knoevenagel condensation cascade reaction. Interestingly, CsCu2I3@PCN-222(Fe) outperforms not only its individual components CsCu2I3 and PCN-222(Fe) but also other reported (photo) catalysts for these transformations. This is attributed to cooperation and synergistic effects of the PCN-222(Fe) host and CsCu2I3 nanocrystals. To understand the catalytic and photocatalytic mechanisms, control and inhibition experiments, electron paramagnetic resonance (EPR) measurements, and time-resolved phosphorescence were performed, revealing the main role of active species of Cu(I) in the click reaction and the superoxide ion (O-2(center dot-)) and singlet oxygen (O-1(2)) in the photocatalytic reaction.