1. College of Science of Taiyuan University of Technology, Taiyuan 030024, China 2. The Key Laboratory of Interface Science and Engineering in Advanced Materials of Taiyuan University of Technology, Taiyuan 030024, China
Abstract：A ligand 5,5′-methylene-bis(8-hydroxyquinoline)(Hqq)was synthesized by condensation reaction at low temperature and was subsequently coordinated to gallium ions to prepare the polymer of tis(5,5′-methylene-bis(8-hydroxyquinoline)gallium (Gaqq3)n. Both chemical structure and phase structure of the ligand and complexes were characterized by Infrared absorption spectrum and X-ray diffraction (XRD). The thermal stability of the complexes was studied by thermogravimetry (TG). The photo-physical properties of the complexes were investigated by ultraviolet absorption spectrum (UV), fluorescence excitation spectrum and emission spectrum. The result indicated that (Gaqq3)n is a thermally stable material, whose decomposition temperature is 443.6 ℃. The ultraviolet absorption bands of (Gaqq3)n are in the range of 250-500 nm, with a relatively strong band tail absorption between 500 and 650 nm, which shows that the band-gap defect states exists in the forbidden band. The fluorescence excitation band of (Gaqq3)n is located at 380-456 nm, and (Gaqq3)n. emits orange-red fluorescence with the emission peak at 568 nm, which shows that the fluorescence emission of (Gaqq3)n is mainly attributed to the charge transfer transitions from phenol to ring pyridine ring, while the π→π* transition of benzene ring is deactivated by non-radiative transition, and makes no contribution to fluorescence emission. (Gaqq3)n optical band gap is 2.49 eV. Compared with the fluorescence emission peak of Gaq3, the fluorescence intensity of (Gaqq3)n decreases, which is attributed to the distortion of the two quinoline rings connected to the methylene，hence leads to the poor rigidity and coplanarity of (Gaqq3)n, thus affects fluorescence emission intensity. Because of the extending of the molecular conjugation system, π electron of (Gaqq3)n is more delocalized, resulting in the redshift of fluorescence emission peak. (Gaqq3)n is expected to be applied in organic light emitting display and organic photovoltaic devices.
Key words：Polymer of tis(5;5′-methylene-bis(8-hydroxyquinoline)gallium (Gaqq3)n;Synthesis;Spectral properties
[1] Tang C W, Vanslyke S A. Appl. Phys. Lett., 1987, 51(12): 913. [2] Tang C W, USA: Society of Information Displays, SID 96 Digest, 1996. [3] Posch P, Fink R, Thelakkat H, et al. Acta Polym., 1998, 49: 487. [4] Friend R H, Gymer R W, Holmes A B, et al. Nature, 1999, 397: 121. [5] Cao Y, Paker I D, Yu G, et al. Nature, 1999, 397: 414. [6] WANG Wei, DING Xiao-ping, MENG Guang-zheng(王 薇，丁小平, 孟广政). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2000, 20(2): 219. [7] LIN Peng, LIANG Chun-jun, DENG Zhen-bo, et al(林 鹏，梁春军, 邓振波, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2005, 25(1): 23. [8] Noda T, Ogawa H, Shirota Y. Adv. Mater., 1999, 11: 283. [9] Gustafsson G, Cao Y, Treacy G M, et al. Nature, 1992, 357: 477. [10] Meyers A, Weck M. Macromolecules, 2003, 36(6): 1176. [11] Xu Bingshe, Hao Yuying, Fang Xiaohong, et al. Appl. Phys. Lett., 2007, 90: 053903. [12] Yu G, Yin S, Liu Y, et al. J. Am. Chem. Soc., 2003, 125: 14816. [13] Colle M, Gmeiner J, Milius W, et al. Adv. Funct. Mater., 2003, 13: 108. [14] Sapochak L S, Padmaperuma A, Washton N, et al. J. Am. Chem. Soc., 2001, 123: 6300. [15] WANG Hua, HAO Yu-ying, GAO Zhi-xiang, et al(王 华，郝玉英，高志翔, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2006, 26(10): 1884. [16] Sapochak L S, Benincasa F E, Schofield R S, et al. J. Am. Chem. Soc., 2002, 124, 6119. [17] MA Dongge, WANG Guang, Hu Yufeng, et al. Appl. Phys. Lett., 2003, 82: 1296. [18] Qiao J, Wang L D, Duan L, et al. Inorg. Chem., 2004, 43: 5096. [19] Yu J, Chen Z, Miyata S. Synthetic Metals, 2001, 123: 239. [20] ZENG Xian-mou, YU Shu-wen, XU Ren-xian(曾献谋, 余淑文, 徐仁贤). Publication about Macromolecule Science Conference of Science Academy of China—Bulletin of Macromolecule Physics-Chemistry and Physical Studies(中国科学院高分子学术会议会刊—高分子物理化学及物理研究工作报告会)(1961). Beijing:Science Press(北京: 科学出版社), 1963. [21] HAO Yu-ying, GAO Zhi-xiang, WANG Hua, et al(郝玉英，高志翔, 王 华, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析)，2006，26(3):491. [22] FANG Rong-chuan(方容川). Solid State Spectroscopy(固体光谱学). Hefei: Press of China University of Science and Technology(合肥: 中国科学技术大学出版社), 2001. 6, 128, 195. [23] HAO Yu-ying, HAO Hai-tao, WANG Hua, et al(郝玉英，郝海涛, 王 华, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2004, 24(12): 1524. [24] HUANG Chun-hui, LI Fu-you, et al(黄春辉，李富友, 等). Ultrathin Films for Optics and Electronics(First Edition)(光电功能超薄膜，第1版). Beijing: Peking University Press(北京: 北京大学出版社), 2001. 160. [25] ZHAO Zao-pan, ZHOU Xing-yao, et al(赵藻藩, 周性尧, 等). Instrumental Analysis(First Edition)(仪器分析, 第1版). Beijing: Higher Education Press(北京: 高等教育出版社), 1992. 158.
