A chiral two-dimensional coordination polymer based on CuII and (S)-4,4′-bis(4-carboxyphenyl)-2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl: Synthesis, structure, and magnetic and optical properties

Abstract

The functionalized binaphthyl derivative (S)-4,4′-bis(4-carboxyphenyl)-2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl (H2L) was employed as linker in the synthesis of the chiral CuII-based two-dimensional network {[Cu2(L)2(dmf)2]·H2O·9dmf}n (1). Single-crystal X-ray analysis showed a two-dimensional structure with a copper paddle wheel as secondary building unit. One dmf molecule is additionally axially coordinated to each Cu cation. A lamellar structure results consisting of alternating [Cu2(L)2(dmf)2]n and solvent (dmf, H2O) layers. According to DTA/TG measurements the coordinated dmf molecules are released at about 320°C, followed by decomposition around 460°C. Magnetic susceptibility measurements on 1 indicate strong antiferromagnetic coupling between the two metal centers in Cu2(L)2(dmf)2. Compound 1 exhibits ligand-based luminescence, assigned to the S1→S0 transition of the aromatic units. Moreover, the emission spectrum of 1 is blueshifted in comparison to H2L, due to different dihedral angles within the respective structures. Activated 1 (heating to 300°C under vacuum for 3h) showed low activity in the catalytic cyanosilylation of benzaldehyde (up to 27.1% conversion) and the isomerization of α-pinene oxide to campholenic aldehyde (up to 15.5% conversion).