Synthesis, Structures And Properties Of 2,2’-Bipyridine And Carbazole-Based Sensitizing Dyes

The series of bipyridine derivatives L1, L2, L3 have been obtained by 4,4’-dimethyl-2,2’-bipyridine. In this paper, bipyridine derivatives are characterized based on’H NMR, MS, FT-IR, UV-Vis and PL. Single crystal X-ray diffraction method was used to determine the crystal structure of LI and L3. FL analysis found that all the derivatives have good fluorescence emission performance. The molecular structures of L1 and L3 in ground state were optimized using density functional theory (DFT). The frontier molecular orbital characteristics were analyzed systematically. Electronic absorption properties were investigated by time-dependent density functional theory (TD/DFT) and compared with experiments.Three complexes (Lable 1,2,3) with L3 have been synthesized and characterized by MS, FT-IR, UV-Vis, PL and TG. These showed that complexes had the general formula of M2(L3)2Cl2·CH3OH·H2O (M= Co, Ni, Cu). The fluorescence properties showed that the intensity of complex 1 was significantly reduced,and complexes 2,3 tend to be weaker comparing with L3. The results of TG analysis indicate that the ligand and complexes have good thermal stability. These studies laid the foundation for the further study of the potential applications.(E)-2-cyano-3-(9-p-tolyl-9H-carbazol-3-yl)acrylic acid (L4) has been obtained and characterized by X-ray diffraction, 1H NMR, MS, FT-IR, and UV-Vis. The vibrational frequencies were calculated using DFT (BHandHLY, PBE1PBE, M062X, B3LYP and CAM-B3LYP) with 6-311++G (d, p) basis set. The predicted electronic absorption spectra were achieved by TDDFT mothed in gas phase and by PCM-TDDFT mothed in methanol solution. The thermodynamic properties, the bond orbital occupancies, contribution from parent NBO, the natural atomic hybrids of L4’s were discussed. The results showed that that L4 has potential applications in dye-sensitized solar cells.