Metallosalen covalent organic frameworks for heterogeneous catalysis

Metallosalen covalent organic frameworks(M(salen)-COFs)have garnered significant attention as promising candidates for advanced heterogeneous catalysis,including organocatalysis,electrocatalysis,and photocatalysis,due to their unique structural advantages(combining molecules catalysts and crystalline porous materials)and tunable topological network.It is essential to provide a comprehensive overview of emerging designs of M(salen)-COFs and corresponding advances in this field.Herein,this review first summarizes the reported metallolinkers and the synthesis methods of M(salen)-COFs.In addition,the review enumerates the excellent M(salen)-COF based heterogeneous catalysts and discusses the fundamental mechanisms behind the outstanding heterogeneous catalytic performance of M(salen)-COFs.These mechanisms include the pore enrichment effect(enhancing local concentration within porous materials to promote catalytic reactions),the three-in-one strategy(integrating enrichment,reduction,and oxidation sites in one system),and the incorporation of a built-in electric field(implanting a built-in electric field in heterometallic phthalocyanine covalent organic frameworks).Furthermore,this review discusses the challenges and prospects related to M(salen)-COFs in heterogeneous catalysis.

Synthesis,structure and property of one porous Zn(salen)-based metal-metallosalen framework

Chiral Schiff-base ligand L was synthesized through six steps in good overall yield from readily available 2-tert-butylphenol and was used to construct one chiral porous metal-metallosalen framework,[Zn5(μ3-OH)2(ZnL)4(H2O)2]·18H2O(1,L=5′,5″-(1E,1′E)-(1R,2R)-cyclohexane-1,2-diylbis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(3′-tert-butyl-4′-hydroxybiphenyl-4-carboxylic acid),under mild reaction conditions.1 was characterized by IR,TGA,CD,UV,PL,single-crystal and powder X-ray crystallography.The structure of 1 displays a 3-fold interpenetrating 3D framework with 1D channel of 1.14 nm×0.58nm and imparts unique Zn(salen)units on the surface of the pore,in which(ZnL)2dimer acts as multi-functionlized metalloligand.1 is thermally robust with network decomposition temperature of 400oC and it also exhibits strong photoluminescence in the visible region.