Controllable Congregating of Homochiral and Achiral Coordination Polymers: Cadmium(II) Pyridine-2,4,6-Tricarboxylate Species with Double-Helical Strand and Molecular Building Block Structures.

Three kinds of three-dimensional (3D) cadmium(II) pyridine-2,4,6-tricarboxylate ( L) coordination polymers, L-[Cd( L)](NH 2Me 2) ( 1a), R-[Cd( L)](NH 2Me 2) ( 1b), [Cd 3( L) 2(H 2O) 4] ( 2), and [Cd 4( L) 2(OH) 2(H 2O) 3](H 2O) ( 3), have been hydro/solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The variations of reaction medium and temperature not only led to an occurrence of spontaneous chiral resolution but also afforded two achrial molecular building block structures. Complexes 1aand 1bcrystallize in trigonal P3 121 and P3 221 space groups with homochiral left- and right-handed double-helical strand arrays, while 2and 3self-assemble into two kinds of achiral coordination polymers with molecular building block structures. Complexes 2and 3remain intact after removal of the coordinated water molecules, which indicates that their dehydrated frameworks possess guest-free metal coordination sites. Complexes 1– 3also display strong fluorescent emissions at 638, 594, and 604 nm in the solid state. [ABSTRACT FROM AUTHOR]