Molecular design and theoretical investigation into one- and two-photon absorption properties of two series of cyclometalated platinum (II) complexes

Abstract

We have theoretically investigated two series of cyclometalated Pt(II) complexes, a series [Pt (C, N, N) Cl] and b series [Pt (C, N, Npyrazolyl) Cl]. The geometrical and electronic structures are calculated at the ECP60MWB//6-31G*(H, C, Cl, N, S) basis set level using DFT method; one-photon absorption (OPA) properties are calculated by using both TDDFT and ZINDO methods and two-photon absorption (TPA) properties are obtained with the ZINDO/SOS method. The resonance integrals parameters ( β sp and β d) for Pt are adjusted to -1 and -28.5 eV, respectively, to make max OPA wavelength calculated by ZINDO closest to the experimental data and TDDFT results. The calculated results indicate the molecule 2b ([Pt (Cnaphthyl, N, Npyrazolyl) Cl]) has the biggest potential as outstanding TPA materials because (i) the TPA properties of b series are more outstanding in IR wavelength range, the molecules in b series have good transparencies and possess 1-pyrazolyl-NH that is also available for another metal coordination (e.g., dimerization) and chemical interactions; (ii) when C is Cnaphthyl in the C, N, N ligand of cyclometalated Pt(II) complexes, the molecules have the best conjugation effect and the best TPA properties.