Synergistic metal and anion effects on the formation of coordination assemblies from a N,N′-bis(3-pyridylmethyl)naphthalene diimide ligand

Abstract

A new semirigid ditopic ligand, N,N′-bis(3-pyridylmethyl)naphthalene diimide (3-pmntd) has been synthesized, and five transition metal complexes, namely, [Cd₂(3-pmntd)₂I₄]·2CHCl₃ (1), [Hg(3-pmntd)Cl₂]_n (2), [Zn(3-pmntd)₂(SCN)₂]_n (3), [Cd (3-pmntd)₂(NO₃)₂]_n (4) and {[Co₂(3-pmntd)₃(NO₃)₄]·2EtOH}_n (5), have been obtained. Complex 1 forms discrete M₂L₂ metallacycles which are linked by C–H⋯O hydrogen bonds and π⋯π stacking interactions to result in a 2D layer. Complex 2 crystallizes in 1D chains which are further connected by C–H⋯O, C–H⋯Cl hydrogen bonds and π⋯π interactions into a 3D framework. Complexes 3 and 4 show a similar structural feature in the formation of non-interpenetrated 2D networks of (4,4) topology, while complex 5 displays a 2D network of (6,3) topology. The structural differences among these complexes are attributed to the different conformations adopted by the ligands, which are primarily induced by different metal centers with coordination environments restrained by different anions. Photoluminescent properties were also studied for selected complexes.