Series of Metal–Organic Frameworks Including Novel Architectural Features Based on a Star-like Tri(4-pyridylphenyl)amine Ligand

Six new metal–organic frameworks with novel structural features based on a star-like ligand tri(4-pyridylphenyl)amine (TPPA), namely, {[Cd(TPPA)(pht)(H 2 O)](H 2 O) 2 } n ( 1 ), {[Zn(TPPA)(pht)](H 2 O) 2 } n ( 2 ), {[Zn(TPPA)( trans -chdc) 0.5 (NO 3 )]·(H 2 O)} n ( 3 ), {[Co(TPPA)(bdc)(H 2 O)]·(H 2 O)} n ( 4 ), {[Co(TPPA)(bdc)(H 2 O)]·(H 2 O) 4 } n ( 5 ), and {[Co(TPPA)(bdc)]} n ( 6 ) (H 2 pht = phthalic acid, trans -H 2 chdc = trans -1,4-cyclohexanedicarboxylic acid, H 2 bdc = benzene- p -dicarboxylic acid), have been synthesized under solvothermal conditions. Compounds 1 – 3 all exhibit fascinating 2D → 3D frameworks with coexistence of inclined polycatenation and polythreading characters. On the other hand, compounds 4 – 6 are three supramolecular isomers. Even though the compositions of 4 – 6 are almost same, they generate different structures. Compound 4 shows a 2D → 3D framework with parallel polycatenation of undulated square layers. Compound 5 reveals 3-fold interpenetrating 3D frameworks with {4.6 2 }{4 3 .6 7 } crs topology. Compound 6 shows a 4-fold interpenetrating 3D metal–organic polyrotaxane framework. In addition, photophysical properties of 1 – 3 and the TPPA ligand in the solid state have also been studied.