Four Metalloporphyrinic Frameworks as Heterogeneous Catalysts for Selective Oxidation and Aldol Reaction

Abstract

Four porous metalloporphyrinic framework materials, [(CH3)2NH2][Zn2(HCOO)2(Mn(III)-TCPP)]·5DMF·2H2O (1; H6TCPP = tetrakis(4-carboxyphenyl)porphyrin), [(CH3)2NH2][Cd2(HCOO)2(Mn(III)-TCPP)]·5DMF·3H2O (2), [Zn2(HCOO)(Fe(III)(H2O)-TCPP)]·3DMF·H2O (3), and [Cd3(H2O)6(μ2-O)(Fe(III)-HTCPP)2]·5DMF (4) were synthesized by heating a mixture of M(III)Cl-H4TCPP (M = Mn and Fe) and M' (M' = Zn or Cd) nitrate in a mixed solvent of DMF and acetic acid. Compounds 1-3 are built up from M'2(COO)4 paddle-wheel subunits bridged by M(III)-TCPP and formate ligands to form their 3D connections. The formate pillar heterogeneously connects with M and M' cations in 1 and 2 and homogeneously joins M' cations in 3. The μ2-O bridged Fe(III)-HTCPP dimer performs as a decadentate ligand to link 10 cadmium cations for the formation of an interesting 3D coordination network of 4. The four porphyrinic frameworks present interesting catalytic properties in the selective epoxidation of olefins, oxidation of cyclohexane, and intermolecular aldol reaction of aldehydes and ketones.