Multi-State Regulation of the Dihydrogen Phosphate Binding Affinity to a Light- and Heat-Responsive Bis-Urea Receptor

A responsive bis-urea receptor can be switched between three isomers using light and heat as evidenced by ¹H NMR and UV–vis spectroscopy. Anion binding experiments (¹H NMR titrations, ESI-MS) reveal a high selectivity for dihydrogen phosphate. Importantly, a large difference in binding affinity to the interchangeable isomers is observed, which is further rationalized by DFT calculations. As a consequence, the amount of bound substrate can be controlled via photo- and thermal isomerization in a three-step process

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

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