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)­(H2O)]­(H2O)2}n (1), {[Zn­(TPPA)­(pht)]­(H2O)2}n (2), {[Zn­(TPPA)­(trans-chdc)0.5(NO3)]·(H2O)}n (3), {[Co­(TPPA)­(bdc)­(H2O)]·(H2O)}n (4), {[Co­(TPPA)­(bdc)­(H2O)]·(H2O)4}n (5), and {[Co­(TPPA)­(bdc)]}n (6) (H2pht = phthalic acid, trans-H2chdc = trans-1,4-cyclohexanedicarboxylic
acid, H2bdc = 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 {4.62}­{43.67} 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.