Extremely Strong Self-Assembly of a Bimetallic Salen Complex Visualized at the Single-Molecule Level

Abstract

A bis-Zn­(salphen) structure shows extremely strong self-assembly both in solution as well as at the solid–liquid interface as evidenced by scanning tunneling microscopy, competitive UV–vis and fluorescence titrations, dynamic light scattering, and transmission electron microscopy. Density functional theory analysis on the Zn₂ complex rationalizes the very high stability of the self-assembled structures provoked by unusual oligomeric (Zn–O)_<i>n</i> coordination motifs within the assembly. This coordination mode is strikingly different when compared with mononuclear Zn­(salphen) analogues that form dimeric structures having a typical Zn₂O₂ central unit. The high stability of the multinuclear structure therefore holds great promise for the development of stable self-assembled monolayers with potential for new opto-electronic materials