Four different double metal cyanides (NiHCFe, CrHCFe, MnHCFe and ZnHCFe) were synthesized, followed by adsorbed on silica gel and used as Lewis acid catalyst in the isomerisation of substituted 2′-hydroxychalcones to flavanones under solvent-free (dry) condition. Optimization of the reaction condition, temperature effects, DMC catalysts loading and re-useable catalytic activity were further studied during the reaction. Among these ...