Self-assembled luminescent Cu(I) tetranuclear metallacycles based on 3,3′-bipyridine ligands

TLDR: In this paper, a 3,3'-Bipyridine ligand was reacted with pre-assembled [Cu-2(mu(2)-dppm)(2)] Cu(I) bimetallic flexible precursor A according to coordination-driven supramolecular chemistry synthetic principles.

Abstract: 3,3'-Bipyridine ligand B was reacted with pre-assembled [Cu-2(mu(2)-dppm)(2)] Cu(I) bimetallic flexible precursor A according to coordination-driven supramolecular chemistry synthetic principles. Outcomes obtained revealed the necessity to formally introduce bridging halide X ions (X = Cl, Br or I) in order to conduct selectively and successfully coordination-driven supramolecular syntheses. Therefore, [Cu-2(mu(2)-dppm)(2)(mu(2)-X)] bimetallic connecting nodes presenting a potential coordination angle of ca. 120 degrees are generated, which lead upon reaction with connecting ligand B to the selective formation of new tetranuclear metallacycles C-X. These derivatives are luminescent in the solid-state at room temperature with high emission quantum yields and a study of the temperature dependence of their photophysical properties was conducted, suggesting a ligand B centered triplet origin for their luminescence.