Syntheses,structures, and fluorescent properties of two helical complexes based on a long rigid N-heterocyclic ligand

A long N-heterocyclic ligand, 2,6-bis(3-(pyrid-3-yl)-1,2,4-triazolyl)pyridine (H₂bptp), and Zn(II)/Pb(II) yield {[Zn(bptp)(H₂O)]?·?2H₂O·CH₃CN} _n (1) and {[Pb(bptp)]?·?H₂O} _n (2). Single-crystal X-ray diffraction analysis reveals that 1 and 2 possess 2-D networks containing alternating left- and right-handed helical motifs. Topologically, 1 features a (4,4) topology, while 2 exhibits a (6,3) topology. The bptp^2? in 1 and 2 adopts syn-anti and syn-syn conformations, respectively. The results indicate that the long rigid N-heterocyclic ligand can adopt different conformations to coordinate with metals, beneficial to construction of helical structures with diverse topologies. The difference between the photoluminescence properties of the two complexes reveals that metal ions and coordination environment have significant influences on photoluminescence behavior.