Synthesis, structure and luminescence properties of a cadmium(ii)-based coordination polymer with (S)-4,4′-bis(4-carboxyphenyl)-2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl as chiral linker

Abstract

Solvothermal reaction of cadmium(II) nitrate with (S)-4,4′-bis(4-carboxyphenyl)-2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl (H₂L) in dimethylformamide (dmf) gave the two-dimensional chiral coordination polymer [{Cd₂(L)₂(H₂O)}·18 dmf]_n (1), which is thermally stable up to 400 °C according to DTA/TG analysis. According to single-crystal X-ray analysis, 1 forms layers in the [01] direction, which are relatively well separated from each other. Compound 1 exhibits ligand-based bluish luminescence, assigned to the S₁→S₀ transition of the aromatic units in L. Emission spectra consist of nearly Gaussian shaped bands with maxima at 25 574 and 24 767 cm⁻¹ for H₂L and 1, respectively. Quantum efficiency reaches a remarkably high value of 42% for the Cd-based coordination polymer and 33% for the respective ligand. Emission intensity of 1 increases from 10 K to room temperature and decreases exponentially for temperatures up to 650 K.