Two Metal-Carboxylate Frameworks Featuring Uncommon 2D+3D and 3-Fold-Interpenetration: (3,5)-Connected Isomeric hms and gra Nets

Two new interpenetrated metal-carboxy late frameworks (MCFs) [(CH3)(2)NH2][Zn-2(BDC)(BTB)][Zn-3(BTB)(2)(H2O2)(2)] center dot 4DMA center dot 2C(2)H(5)OH center dot 7H(2)O (MCF-25, 1, H2BDC = 1,4-benzenedicarboxylic acid, H3BTB = benzene-1,3,5-tribenzoic acid), and [(CH3)(2)NH2][Zn-2(BDC)(BTB)] center dot 3DMF center dot 2HO (MCF-26, 2), synthesized by solvothermal reaction and room-temperature evaporation, respectively, are constructed by Zn-2,(O2CR)(5) (in 1 and 2) and Zn-3(O2CR)(6) (in 1) units incorporating mixed BDC2- and BTB3- ligands. I is composed of two different frameworks with 2D 6(3) bilayers and a rare (3,5)-connected 3D hms net giving all interesting 2D + 3D framework, whereas 2 features a novel 3-fold interpenetrated (3,5)-connected gra net with chiral, hexagonal helical channels. Structural analysis shows that the two 3D nets of hms in I and gra in 2 are strict isomers with the same components but different steric arrangements, which are derived from different orientations of the two axial carboxylate bridges in two isomeric Zn-2(O2CR)(5) SBUs.