Zn[Htma][ddm]: An interesting three-dimensional chiral nonlinear optical-active zinc-trimesate framework

The three-dimensional (3D) chiral helical framework of the new polymeric solid, Zn[Htma][ddm] (1) (tma = trimesate, ddm = p,′-diamino-diphenyl- methane), has been prepared by the hydrothermal reaction of zinc acetate dihydrate, H₃tma, and ddm. X-ray single-crystal structural analysis reveals that 1 (C₂₂H₁₈N₂O₆Zn) crystallizes in the orthorhombic P2₁2₁2₁ space group, Z = 4 (a = 5.4533(3) Å, b = 17.593(1) Å, c = 20.542(1) Å, V = 1970.8(2) ų). Tetrahedrally coordinated zinc centers in 1 bridged by the rigid trigonal tectonic tma ligands with A-configuration plus the flexible ddm molecules give rise to an interesting 3D chiral helical diamondoid network single enantiomer that has been confirmed by solid-state circular dichroism spectra. 1 is stable up to about 297°C in the ambient environment and exhibits an intense fluorescent emission band at 420 nm upon excitation at 326 nm and the band gap semiconducing character. The theoretical calculations reveal that 1 is a potential nonlinear optical-active material.