Formation of a Chiral Host with Axially Chiral Cationic 1D Coordination Polymers Composed of Achiral Building Blocks and Inclusion of Anionic Tris-Chelate Complexes in an Unbalanced A/A Ratio

摘要

Two crystals, [{Co(hfac)_2} {Ni(pyterpy)_2}][Co(hfac)_3]_2(1) and [CNacac)_2][2]SO_4·xG (2), composedof 1D cationic coordination polymers were prepared by self-assembly of achiral component metal complexes in solu-tion (hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionato, CNacac = 3-cyanopentane-2,4-dionato, pyterpy = 4'-(4-pyri-dyl)-2,2':6',2"-terpyridine, G = methanol and water). 1 is chiral and spontaneously optically resolved, whereas 2 isachiral. In 1, an alternate linkage of [Co(hfac)2] and [Ni(pyterpy)2]2+ forms a 1D coordination polymer and twisting of thetwo complexes about the principal axis of the 1D polymer makes the polymer axially chiral. The ID polymers stack tocreate two-types of 1D channels, where anionic complexes [Co(hfac)3]- are included. One channel contains onlyA-[Co(hfac)3]-, whereas the other contains an equal amount of A- and A-[Co(hfac)3]-. Therefore, the A/A ratio of[Co(hfac)3]- is 3/1. In the case of 2, 1D coordination polymers are formed by an alternate linkage of [Co(CNacac)2] and[Ni(pyterpy)2]2+. They are chiral due to twisting of one pyridine ring in [Ni(pyterpy)2]2+, however, there are inversioncenters in 2. These results demonstrated that axial chirality can be introduced into ID coordination polymers by twistingthe two component metal complexes alternately linked. This method is useful and prospective for preparing chiralcoordination polymers from achiral building blocks.