Toward metal complexes that can directionally walk along tracks: controlled stepping of a molecular biped with a palladium(II) foot.
We report on the design, synthesis, and operation of a bimetallic molecular biped on a three-foothold track. The "walker" features a palladium(II) complex "foot" that can be selectively stepped between 4-dimethylaminopyridine and pyridine ligand sites on the track via reversible protonation while the walker remains attached to the track throughout by means of a kinetically inert platinum(II) complex foot. The substitution pattern of the three ligand binding sites, together with the kinetic stability of the metal-ligand coordination bonds, affords the two positional isomers a high degree of metastability, meaning that altering the chemical state of the track does not automatically instigate stepping in the absence of an additional stimulus (heat in the presence of a coordinating solvent). The use of metastable metal complexes for foot-track interactions offers a promising alternative to dynamic covalent chemistry for the design of small-molecule synthetic molecular walkers.
School of Chemistry, University of Edinburgh , The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, United Kingdom.
Jonathon E
JE
Beves
Victor
V
Blanco
Barry A
BA
Blight
Romen
R
Carrillo
Daniel M
DM
D'Souza
David
D
Howgego
David A
DA
Leigh
Alexandra M Z
AM
Slawin
Mark D
MD
Symes
D001665:Binding Sites; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013816:Thermodynamics
C417980:4-(dimethylamine)pyridine; D056831:Coordination Complexes; D008024:Ligands; D011725:Pyridines; D010984:Platinum; D010165:Palladium