Pyridine Coordination Chemistry for Molecular Assemblies

Milko van der Boom, Weizmann Institute, Rehovot, Israel

Since the description of coordination complexes many types of metal-ligand interactions have creatively been used in the chemical sciences. The rich coordination chemistry of pyridine-type ligands has contributed significantly to the incorporation of metal ions into functional materials. Here we discuss molecular assemblies (MAs) formed with a variety of pyridine-type compounds. These MAs are formed by layer-by-layer deposition from solution that allows for precise fitting of the assembly properties. The degree of intermolecular interactions can be controlled by varying the degree of p-conjugation and the availability of coordination sites. Unlike MAs that are constructed with organic ligands, MAs with polypyridyl complexes are active participants in their own formation and amplify the growth of the incoming molecular layer. Such a self-propagating behavior for molecular systems is rare and the mechanism of their formation will be discussed. Incorporating multiple metal complexes into a single assembly give rise to composite materials that exhibit electrochemical and electrochromic properties that are dependent on the arrangement of these metal complexes. Some of these MAs are also discussed in terms of their practical applications and future directions are given according to the lessons we have learned from our previously assembled molecular structures.