A Chemically Fuelled Molecular Automaton Displaying Programmed Migration of Zn2+ Between Alternative Binding Sites

• Published in: Chemistry : a European journal 2022-10, Vol.28 (59), p.e202202247-n/a
• Main Authors: Wootten, Matthew M., Tshepelevitsh, Sofja, Leito, Ivo, Clayden, Jonathan
• Format: Article
• Language: English
• Subjects: Acidity; Amino acids; Basicity; Binding sites; Carbon dioxide; Cations; chemical fuel; Chemistry; Chloroform; Chromophores; Circular dichroism; Dichroism; host-guest systems; metal complexes; Metal ions; Moisture content; molecular automata; Trichloroacetic acid; Triethylamine; Water content; Zinc; Zinc compounds
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202202247

A molecular system comprising a cationic zinc complex and an amino acid‐derived ambident ligand having phosphate and carboxylate binding sites undergoes a series of rearrangements in which the metal cation migrates autonomously from one site to another. The location of the metal is identified by the circular dichroism spectrum of a ligated bis(2‐quinolylmethyl)‐(2‐pyridylmethyl)amine (BQPA) chromophore, which takes a characteristic shape at each binding site. Migration is fuelled by the decomposition of trichloroacetic acid to CO2 and CHCl3, which progressively neutralises the acidity of the system as a function of time, revealing in sequence binding sites of increasing basicity. The migration rate responds to control by variation of the temperature, water content and triethylamine concentration, while an excess of fuel controls the duration of an induction period before the migration event. Programmed autonomous migration of cations between alternative binding sites of a peptidomimetic ligand is driven by a fuelled change in acidity of the system. The rate of migration, and delays or resets in the execution of the program, may be controlled by the operating conditions of the molecular automaton.