Noncovalent-Bonded 3d Cd(Ii) And Zn(Ii) Supramolecular Metal-Organic Frameworks From 3,3 ',5,5 '-Tetramethyl-4,4 '-Bipyrazole And Carboxylates

The present study pertains to the syntheses and characterizations of four mixed-ligand complexes of Cd(H(2)Bpz)(L1)(2)(H2O) (1) (L1 = 2-methyl-2-phenoxypropanoic acid), Zn(H(2)Bpz)(L2)(2) (2) (L2 = m-nitrobenzoate), Cd(H(2)Bpz)(2)(L3)(2) (3) (L3 = 3,4-(methylenedioxy)benzoate) and [Cd-2(H(2)Bpz)(3)(L4)(2)](2)center dot 2(THF)(0.5)center dot 4MeOH center dot 4H(2)O (4) (L4 = o-phthalate). The resulting complexes were formulated via EA, IR and SCXRD, and the TGA. X-ray studies revealed that these complexes have mononuclear to dinuclear structures with distorted octahedral geometry at Cd2+ and square pyramidal geometry for Zn2+, and metal ions show N2O3, N2O4, N3O3 and N4O2 bonding cores. H(2)Bpz in all compounds is coordinated only in bismonodentate fashion with its neutral N. The CO2- in 1 and 4 exhibited bisunidentate and monodentate coordination units, the CO2- in 2 has both chelating bidentate and monodentate coordination mode, and the CO2- in 3 is only monodentate. The CH3 of H(2)Bpz in all compounds except 1 participated in noncovalent bonds. Complexes 1-4 have many intra- and intermolecular weak interactions (including classical H-bonds, O center dot center dot center dot O, C-H center dot center dot center dot O, CH2 center dot center dot center dot O, CH3 center dot center dot center dot O, C-H center dot center dot center dot pi, CH2 center dot center dot center dot pi, CH3-pi, OH-pi and pi-pi interactions) in their crystals, which lead to the total 3D supramolecular structures. The thermal stabilities for 1-4 show that the complexes are good candidates for hybrid inorganic-organic materials with good thermal stability.