Synthesis And Photoelectric Properties Of Schiff Base Complexes Containing Triphenylamine Unit

Nowadays, triphenylamine and its derivatives in the functional field are attracted much attention due to the electron-donating ability, low redox protential, the excellent ability of hole-transfer, good solubility and easily film-formation. Therefore, they can be widely applied in the field of non-liner nonlinear optical materials, electrochromism and solar cells. In this paper, a series of Schiff-base ligands and their complex with triphenylamine group have been designed and synthesized based on the investigation of the literature. Main research results obtained were concluded as following.1. Four triphenylamine-based Schiff-base ligands were synthesized, including4,4’-diethoxy-4"-((2-pyridyl methylene)amidogen)-triphenylamine (abbreviated as L1),4,4-diethoxy-4"-((2-hydroxylphenyl methylene)amidogen)-triphenylamine (abbreviated as L2),4-(2-pyridyl methylene)amidogen) triphenylamine (abbreviated as L3),4-(2-hydroxylphenylmethylene)-amidogen)-triphenylamine (abbreviated as L4). The compounds were characterized by IR,1H NMR and Mass spectra. The structures of L1, L2and L4were also characterized by single-crystal X-ray diffraction analysis. The results showed that L1and L2belonged to the orthorhombic crystal system with space group of P212121, while L4belonged to the monoclinic crystal system with space group of P21/c.2. Six complexes were obtained by the reaction of L1, L3with Ni (SCN)2, Zn (SCN)2, ZnI2, respectively. The metal coordination molecule, Ni (L1)2(SCN)2, crystallized in orthorhombic crystal system with the space group of Pbcn. The Coordination geometry of Ni atom was a distorted octahedron with four nitrogen atoms from two L1molecules and two nitrogen atoms from SCN-anions. The two L1molecules and Ni atom formed two five-membered rings with orthogonality.3. Investigation on the photo-and electric-properties of the ligands and the complexesThe UV-vis spectra of the ligands and the complexes showed that, compared with the ligands, the bands of the absorption wavelength (λabs-max) of the complexes have no changed in for their bands at the short wavelength, while that showed blue-shift in for their bands at the long-wavelength. The phenomena can be explained on the interactions between the complexes and solute molecules, which can reduce the energy of the ground state. Though time-dependent density functional theory (TD-DFT) calculation, the UV-vis absorption of the ligands and the complexes were discussed. Besides, a new band at～500nm appeared after the ligands combined with Zn2+ion (with d10structure), which can be explained as the metal-ligand charge transfer (MLCT).The non-linear properties of the ligands and the complexes were using through Z-scan method with the femtosecond laser. The results showed that L1, Zn(L1)2(SCN)2and Zr(L1)2I2had excellent two-photon absorption (TPA) effect.The cyclic voltammetry and electrochemical luminescence for the ligands and the complexes were studied. The results indicated that their potentials of the complexes shift forward positive compared.