Syntheses and crystal structures of a series of coordination polymers constructed from C2-symmetric ligand 1,3-adamantanedicarboxylic acid

Abstract

This article systematically investigates the influence of the properties of inhomogeneous N-auxiliary ligands and pH value on the helical structures of complexes based on C(2)-symmetric ligand 1,3-adamantanedicarboxylic acid (H(2)ADC). Five kinds of neutral ligands (phen=1,10-phenanthroline, bipy=4,4'-bipyridine, bpa=1,2-bis(4-pyridyl)ethane, bpe=1,2-bis(4-pyridyl)ethane, and bpp=1,3-bis(4-pyridyl)propane) were selected, and a series of new Zn(II)/Co(II) dicarboxylates have been synthesized by slow diffusion, namely, [Zn(phen)(ADC)(H(2)O)](2).CH(3)OH (1), {[Zn(ADC)(bpe)].H(2)O}(n) (2), {[Zn(ADC)(bipy)].2H(2)O}(n) (3), {[Zn(ADC)(bpa)](2).5H(2)O}(n) (4), {[Zn(ADC)(bpp)](2).CH(3)OH}(n) (5), {[Zn(ADC)(bpp)]}(n) (6), {[Co(ADC)(bpp)(CH(3)OH)(H(2)O)].CH(3)OH2 H(2)O}(n) (7), and {[Co(ADC)(bpp)]}(n) (8). Single-crystal X-ray structural analysis shows that complex 1 forms a 0D dinuclear with closed-loop unit. The complex 2 is a 2D layer framework. Compounds 3 and 4 are isomorphous with a small discrepancy and present one-dimensional chainlike structures. It is interesting that the 2D organic-inorganic hybrid frameworks containing meso-helical chains have been observed. Compound 5 is a 2D interpenetrated network with (4,4) topology, in which homochiral left-handed helical chains are arranged in an ABAB sequence parallel to the plane defined by (a,c), and right-handed helical chains running along the a axis are also observed in the solid state, resulting in a meso-helical structure. Compounds 6, 7, and 8 crystallize in a chiral space group P212121. Highly dimensional 6 and 8 are essentially isostructural and present a threefold interpenetrated 3D diamondoid network containing three helical chains, whereas 7 exhibits a 2D grid layer with a left-handed helical chain. Furthermore, thermal stability, X-ray powder diffraction, and the luminescent properties of 1-6 are also discussed.