Crystal structure and optical property of a Cadmium(II) complex based on triphenylamine derivative—Theoretical and experimental investigation

Abstract A triphenylamine derivative (E)-N,N-diphenyl-4-(2-(pyridin-2-yl)vinyl)benzenamine (L) was synthesized, and the corresponding cadmium complex CdI2L2 crystal was obtained and solved by single crystal X-ray diffraction analysis. The experimental resutls of one photon absorption (OPA) and one photon excited fluorescence (OPEF) indicate that coordination of CdI2 only has slight effect on the spectrum peak position relative to the free ligand. Besides the Stokes shift, the full width half maximum of OPEF and the variation of the “peak span between solvents” from OPA to OPEF can also indicate the electron transition direction of the excitation process. The laser experiments show that both the ligand and complex have considerable two photon excited fluorescence (TPEF) emission. The experimental Stokes shift is correlated with the computational solvent polarity rMPI, and the results illustrate that the curve of “experimental Stokes shift vs. solvent rMPI” is exactly the Boltzmann S-curve. The computational results also indicate that the static interaction between the CdI2L2 molecules in crystal has strong effect on OPA properties. Considering the weak coordination bond strength of the complex CdI2L2, the S1→S0′ fluorescence emission may occur on both ligands, although the S0→S1′ excitation only occurs on the right ligand.