Rational Design of a 3D MnII -Metal-Organic Framework Based on a Nonmetallated Porphyrin Linker for Selective Capture of CO2 and One-Pot Synthesis of Styrene Carbonates.

A 3D MnII -porphyrin metal-organic framework (MOF), [{Mn2 (TCPP)⋅2H2 O}⋅DMF]n (MOF1) (TCPP=5,10,15,20-tetrakis(4-benzoate)porphyrin), was constructed; it exhibits an interesting 3D framework structure with two types of 1D channels of dimensions of 3.94×8.37 Å2 and 4.66×4.93 Å2 running along the crystallographic a axis. Owing to the presence of a nonmetallated porphyrin cavity, MOF1 exhibits selective storage of CO2 with an isosteric heat of adsorption value of 32.1 kJ mol-1 , which is further supported by theoretical calculations with the calculated binding energy (BE) of 29.78 kJ mol-1 . Interestingly, the nonmetallated nature of the porphyrin ligand was exploited for implantation of coordinatively unsaturated FeIII ions to generate a FeIII @MOF1 framework, which acts as an efficient recyclable catalyst for the oxidation of styrenes to the corresponding epoxides in the presence of PhIO as an oxidant at room temperature. Moreover, the one-pot synthesis of styrene carbonates from styrenes and CO2 was also achieved using FeIII @MOF1 as a catalyst. The rational design of a porous MnII -porphyrin MOF for the selective capture of CO2 and the one-pot synthesis of styrene carbonates at mild conditions is reported.

Rational Design of a Bifunctional, Two-Fold Interpenetrated ZnII -Metal-Organic Framework for Selective Adsorption of CO2 and Efficient Aqueous Phase Sensing of 2,4,6-Trinitrophenol.

A bifunctional, microporous ZnII metal-organic framework, [Zn2 (NH2 BDC)2 (dpNDI)]n (MOF1) (where, NH2 BDC=2-aminoterephthalic acid, dpNDI=N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide) has been synthesized solvothermally. MOF1 shows an interesting two-fold interpenetrated, 3D pillar-layered framework structure composed of two types of 1D channels with dimensions of approximately 2.99×3.58 Šand 4.58×5.38 Šdecorated with pendent -NH2 groups. Owing to the presence of a basic functionalized pore surface, MOF1 exhibits selective adsorption of CO2 with high value of heat of adsorption (Qst =46.5 kJ mol-1 ) which is further supported by theoretically calculated binding energy of 48.4 kJ mol-1 . Interestingly, the value of Qst observed for MOF1 is about 10 kJ mol-1 higher than that of analogues MOF with the benzene-1,4-dicarboxylic acid (BDC) ligand, which establishes the critical role of the -NH2 group for CO2 capture. Moreover, MOF1 exhibits highly selective and sensitive sensing of the nitroaromatic compound (NAC), 2,4,6-trinitrophenol (TNP) over other competing NACs through a luminescence quenching mechanism. The observed selectivity for TNP over other nitrophenols has been correlated to stronger hydrogen bonding interaction of TNP with the basic -NH2 group of MOF1, which is revealed from DFT calculations. To the best of our knowledge, MOF1 is the first example of an interpenetrated ZnII -MOF exhibiting selective adsorption of CO2 as well as efficient aqueous-phase sensing of TNP; investigated through combined experimental and theoretical studies.

Visible-Light-Assisted Photocatalytic Reduction of Nitroaromatics by Recyclable Ni(II)-Porphyrin Metal-Organic Framework (MOF) at RT.

A microporous Ni(II)-porphyrin metal-organic framework (MOF), [Ni3(Ni-HTCPP)2(µ2-H2O)2(H2O)4(DMF)2]·2DMF, (MOF1) (where, Ni-HTCPP = 5,10,15,20-tetrakis(4-benzoate) porphyrinato-Ni(II)) has been synthesized by the solvothermal route. Single-crystal X-ray diffraction study of 1 reveals a 2D network structure constituted by Ni3 cluster and [Ni-HTCPP](3-) metalloligand having (3, 6)-connected binodal net with {4(3)}2{4(6)·6(6)·8(3)}-kgd net topology. The 2D layers are further stacked together through π-π interactions between the porphyrin linkers to generate a 3D supramolecular framework which houses 1D channels with dimension of ∼5.0 × 9.0 Å(2) running along the crystallographic a-axis. Visible-light-assisted photocatalytic investigation of MOF1 for heterogeneous reduction of various nitroaromatics at room temperature resulted in the corresponding amines with high yield and selectivity. On the contrary, the Ni(II)-centered porphyrin tetracarboxylic acid [Ni-H4TCPP] metalloligand does not show the photocatalytic activity under similar conditions. The remarkably high catalytic performance of MOF1 over [Ni-H4TCPP] metalloligand has been attributed due to cooperative catalysis involving the Ni-centered porphyrin secendary building units (SBUs) and the Ni3-oxo node. Further, the MOF1 was recycled and reused up to three cycles without any significant loss of catalytic activity as well as structural rigidity. To the best of our knowledge, MOF1 represents the first example of MOF based on 3d metal ion exhibiting visible-light-assisted reduction of nitroaromatics under mild conditions without the assistance of noble metal cocatalysts.