The side chain template effect in viologen on the formation of polypseudorotaxane architecture: six novel metal coordination polymers and their properties

Abstract

The reaction of CuSCN (or CuCl₂) in the presence of excess KSCN directed by viologen-based linear templates in a dimethyl formamide–methanol system affords six coordination polymers, {(MV)[Cu₂(SCN)₄]}_n (1, MV²⁺ = 1,1′-dimethyl-4,4′-bipyridinium), {(PrV)[Cu₂(SCN)₄]}_n (2, PrV²⁺ = 1,1′-dipropyl-4,4′-bipyridinium), {(iPV)[Cu₂(SCN)₄]}_n (3, iPV²⁺ = 1,1′-diisopropyl-4,4′-bipyridinium), [(1-iBV)Cu₂(SCN)₃]_n (4, 1-iBV²⁺ = 1-isobutyl-4,4′-bipyridinium), {(iBV)[Cu₂(SCN)₄]}_n (5, iBV²⁺ = 1,1′-diisobutyl-4,4′-bipyridinium), and {(PtV)[Cu₂(SCN)₄]}_n (6, PtV²⁺ = 1,1′-dipentyl-4,4′-bipyridinium). The [Cu₂(SCN)₄]_n anion in compounds 1, 3 and 5 adopts an infinite two-dimensional polypseudorotaxane architecture and proved effectively that the stoppers at the end can enhance the polyrotaxane formation in the crystalline state, whereas the anion moieties in compounds 2 and 6 exhibit one-dimensional linear architectures, suggesting dethreading from envelopes once solidifying from solution phase. Compound 4 was found to be a two-dimensional coordination polymer with the organic ligand carrying a single charge. The side chain template effect of substituted group, UV-Vis diffuse reflectance spectra in the solid state and TGA properties of the six complexes are investigated.