Synthesis, crystal structure and luminescent behaviour of coordination complexes of copper with bi- and tridentate amines and phosphonic acids

Abstract

The synthesis and crystal structure of four new copper(I) and copper(II) supramolecular amine, and amine phosphonate, complexes is reported. Reaction of copper(I) with 2-,9-dimethyl-1-10-phenanthroline ( dmp) produced a stable 4-coordinate Cu(I) species, [Cu (I)( dmp) 2]Cl · MeOH · 5H 2O ( 2), i.e., the increased steric hindrance in the ‘bite’ area of dmp did not prevent interaction with the metal and provided protection against oxidation which was not possible for the phen analogue [R. Clarke, K. Latham, C. Rix, M. Hobday, J. White, CrystEngCommun. 7(3) (2005), 28–36]. Subsequent addition of phenylphosphonic acid to ( 2) produced two structures from alternative synthetic routes. An ‘ in situ’ process yielded red block Cu(I) crystals, [Cu (I)( dmp) 2] · [C 6H 5PO 3H 2 · C 6H 5PO 3H] ( 4), whilst recrystallisation of ( 2) prior to addition of the acid (‘ stepwise’ process) produced a green, needle-like Cu(II) complex, [Cu (II)( dmp) · (H 2O) 2 · C 6H 5PO 2(OH)] [C 6H 5PO 2(OH)] ( 3). However, addition of excess dmp during the ‘ stepwise’ process forced the equilibrium towards product ( 4) and resulted in an optimum yield (99%). The structure of ( 4) was similar to the phen analogue, [Cu (II)Cl( phen) 2] · [C 6H 5PO 2(OH) · C 6H 5PO(OH) 2] ( 1) [R. Clarke, K. Latham, C. Rix, M. Hobday, J. White, CrystEngCommun. 7(3) (2005), 28–36], but the presence of dmp exerted some influence on global packing, whilst ( 3) exists as a polymeric layered material. In contrast, reaction of copper(I) with di-2-pyridyl ketone ( dpk), followed by phenylphosphonic acid produced purple/blue Cu(II) species, [Cu (II)( dpk · H 2O) 2] Cl 2 · 4H 2O ( 5), and [Cu (II)( dpk · H 2O) 2] · [C 6H 5PO 2(OH) 2 · C 6H 5PO(OH) 2] ( 6), respectively, i.e., in both cases oxidation of copper occurred. Solid-state luminescence was observed in ( 2) and ( 4). The latter showing a 5-fold enhancement in intensity.