Design, Synthesis, Structural Characterization And Luminescent Investigation Of Copper(I) Complexes Based On Bridging Bipyrazole Ligands

The design and synthesis of complexes featuring special luminescent properties are not only a hot topic, but also an important theme of coordination chemistry. The luminescent properties of the complexes are controlled by the structures, specifically by the ligand structures, the inherent properties of the metal ions and the reaction conditions.In this work, a series of semirigid bipyrazole ligands with the bridging Ligands of xylylen and varied substituents on the 3- and 5-position of the pyrazole rings were designed and synthesized. Using these ligands to react with copper salt under different reaction conditions, a series of coordination compounds, ranging from 0D to 3D, non-interpenetrating to 4-fold interpenetrating and 5-fold interpenetrated, and also a triangular prism cage, were constructed successfully. Moreover, we rationalized the photophysical properties of the targeted cage not only experimentally but also through theoretical calculations. This work represented the research framework of design?synthesis?property?rationalization unambiguously.In Chapter 1, closely related research progresses in the field of coordination chemistry were introduced: i) four methods of constructing complexes by self-assembly in crystal engineering; ii) three strategies of constructing prism complexes; iii) experimental and theoretical investigations on the luminescent property of coordination complexes. In addition, research progresses on pyrazole-based coordination complexes were reviewed briefly, and the purpose and significance of this work were outlined.In Chapter 2, four bipyrazole ligands with various substituents in 3- and 5-position, angular m-xylylen-bis(3,5-dimethyl)pyrazole (L1) and m-xylylen-bis(3,5-phenyl)pyrazole (L2), and linear p-xylylen-bis(3,5-dimethyl)pyrazole (L3) and p-xylylen-bis(3-dimethyl,5-phenyl)pyrazole (L4) were synthesized and characterized by IR spectrum and X-ray diffraction.In Chapter 3, two new complexes, 1 [Cu6(L1)3] and 2 [Cu4(L2)2] with typical structures of a hexanuclear prism cage and a tetranuclear cluster, were obtained successfully under hydro(solvo)thermal conditions using angular L1 and L2 as ligands. In both complexes the copper(I) atoms showed linear coordination mode. We further rationalized the intrinsic photophysical properties of complex 1 not only experimentally but also through theoretical calculations. Herein, a research framework of design?synthesis?property?rationalization for predesigned complex was constructed.In Chapter 4, three new complexes, 3 [(CuI)2(L3)]n, 4 [(CuI)2(L4)]n and 5 [(CuI)8(L4)3]n were obtained successfully under hydro(solvo)thermal conditions using linear L3 and L4 as ligands to react with CuI. The structures of 3 and 4 showed five-fold interpenetration with Cu4I4 acting as Secondary Building Units (SBUs) linked by pyrazole-N atoms, while structure 5 showed four-fold interpenetration consisted of Cu8I8 SBUs linked by pyrazole-N atoms. Moreover, complexes 3 and 4 displayed different luminescent properties due to different substituents on 3- and 5-position of the pyrazole rings, and complexes 4 and 5 also displayed different luminescent properties due to diverse copper-cluster SBUs. This chapter offers insights to investigate the luminescent properties of copper-halides-cluster based coordination polymers.In Chapter 5, three three new complexes, 6 [Cu2(CN)2(L3)(hexane)]n, 7 [Cu4(SCN)2(CN)2(L3)]n and 8 [Cu4(SCN)2(CN)2(L4)]n were obtained successfully under hydro(solvo)thermal conditions using linear L3 and L4 as ligands to react with CuCN and CuSCN. The three structures all showed two-dimensional sheet-like networks. Moreover, complexes 7 and 8 with similar topology displayed different luminescent properties due to diverse electron-withdrawing or pushing substituents on 3- and 5-position of the pyrazole rings. This chapter offers insights to investigate the luminescent properties of copper-pseudohalides based coordination polymers.