Z-scan measurements and TDDFT study of the two-photon absorption properties of diaqua-bis(4-hydroxy-3-methoxybenzaldehyde)-cobalt(II)

A cobalt complex constructed by the ligand(L): 4-hydroxy-3-methoxybenzaldehyde [Co(C8H7O3)(2)(H2O)(2)] has been synthesized and characterized by X-ray single crystal diffraction. The cobalt(II) atom is six-coordinate in a distorted octahedral geometry, intermolecular O-H center dot center dot center dot O hydrogen bonds lead to the formation of a two-dimensional supramolecular network along ab plane. Its thermal stability was determined by TGA/DSC. Its two-photon absorption (TPA) cross-section sigma(2) value and second hyperpolarizability value were determined to be 1.59 x 10(-53) (m(4) s/photon molecule) and 1.06 x 10(-56) (C m(4)/V-3) by Z-scan technique with 20 picosecond (ps) pulses at wavelength 1064nm. The value is about six times larger than the time-dependent density-functional theory (TDDFT) calculation results.