LAUSR

Abstract A reaction of 2-((pyridin-4-yl)methylamino)-4-(methylthio)butanoic acid (HL) and Zn(OAc)2.2H2O afforded a hexacoodinated coordination polymer of [Zn(L)(HL)(H2O)2]n (Zn-1). When the single crystals of Zn-1, are suspended in water-DMF (2:1) solution of Cu(OAc)2.H2O, a quantitative metal exchange occurred resulting an isomorphous structure [Cu(L)(HL)(H2O)2]n (Cu-1) via a single-crystal-to-single-crystal mediated route. The metal exchange process can be clearly monitored with visual colour change in solid state and supported by spectroscopic evidences. However, attempt to obtain Cu-1 via a direct reaction route under identical condition, afforded a completely different compound [Cu(L)(CH3COO)]n (Cu-2). Various counter ions of different Cu-sources as well as solvent types play an important role for the above metal exchange process. All the coordination polymers are unequivocally characterized by single crystal X-ray crystallography and other spectroscopic methods. The above metal exchange is unique as Cu-1 can be only synthesized by metal exchange route and follows the Irving–Williams series of stability for Cu(II) over Zn(II).