Entanglement of individual coordination polymers having helicates as building intermediates

Abstract

A series of Ag(I) coordination compounds, from one-dimensional chains to 3D porous frameworks, were achieved from N,N′-bis[1-(2-pyrazinyl)ethylidene]benzil dihydrazone, L, via self-assembly, using helicates as effective secondary building units. Compound 2 [(Ag_2.75L)(NO₃)_2.75] was comprised of two opposite-handed 3D frameworks formed by connecting the 4₁ helical chains into (10³-b) nets. The pairs of the racemic 3D frameworks were connected through additional silver(I) centers and entangled each other forming a racemic 3D net. Compound 3 [(Ag₁₃L₈)(BF₄)₁₃(H₂O)₁₂] was comprised of a 3D framework that was constructed from double-helical building intermediates Ag₂L₂ with one-dimensional infinite chains being threaded into the large voids of a 3D framework to form a weave structure. The ladder-like chains in compound 4 [(Ag₃L₂)(ClO₃)₃(CH₃OH)₂(CH₃CN)] were formed by the addition of excess NaClO₃ into the methanol solution containing AgNO₃ and the ligand L, and the zigzag chains in compound 5 [(Ag₂L₂)(ClO₄)₂(CH₃CN)₂] were constructed by the addition of excess NaClO₄ into an acetonitrile solution containing AgNO₃ and the ligand L.