Molecular Recognition of a Peptide by the Nickel(II) Complex of 1,4,7,10‐Tetraazacyclododecane‐2,9‐dione

The nickel(II) complex of the macrocycle 1,4,7,10‐tetraazacyclododecane‐2,9‐dione (dota) was found to be efficient in the recognition of the dipeptide, glycyl‐glycine (Gly‐Gly) in aqueous solution. This (dota)Ni^II complex serves as a targeting molecule to form a stable ternary complex with the dipeptide at pH 8.3 in aqueous solution. The recognition constant (log K=19.20) and the recognition mechanism were investigated based on the potentiometric method. The single‐crystal of a six‐coordinated (dota)₂Ni^II complex is also reported.