Research, Synthesis, Structure And Properties Of Novel Pyridine Pyrazole - Metal Clusters Based Complexes

Bottom-up construction of metal-organic coordination polymers with desired structure and property, by selecting metals and organic ligands, is the central mission of crystal engineering. Scientists are trying to fabricate the functional materials via pre-designed setting up of molecular building blocks. As preparation for this practice, rational design of the structures of coordination polymers has garnered considerable interest in recent years. In general, the structures of coordination polymers are based upon the coordination preference of building blocks and the predication of properties depends on the presence of special functionalized groups.In this dissertation, a series of4-(4-pyridyl)pyrazole ligands (Hdmppz, Hdeppz and Hdpppz) with different substituent groups in3,5-position of pyrazole ring have been designed and synthesized. As potential tridentate ligands, these ligands combine the coordination features of pyrazole and pyridine. The former is expected to form cyclic trinuclear or tetranuclear unit with linear coordinated coinage metals, which can be further extended into a one-(1D), two-(2D) and three-dimensional (3D) coordination polymers by the coordination of pyridyl units of the ligands. Sparked by this strategy,17novel complexes have been obtained and characterized by element analysis, infrared spectra, X-ray single diffraction analysis, them-gravimetric analysis, luminescence, powder X-ray diffraction analysis and fluorescence measurements, we discussed the influence of the substituents of ligands and metal ions on the structures and properties of complexes. The dissertation includes five chapters:In chapter1, the current progress, especially the survey of coordination complexes constructed from pyrazole and its derivatives is introduced, including complexes containing mono-pyrazole, di-pyrazole, tri-pyrazole and1,2,4-triazole which is similar with the ligands in this dissertation. In addition, the progress of this work is also outlined.In chapter2, seven planar cyclic Cu(I)/Ag(I) trimer clusters featuring nine-membered M3N6metallocycles were assembled by using4-(4-pyridyl)pyrazole ligands with different substituents (Hdmppz, Hdeppz and Hdpppz) and d10metal ions (Cu(Ⅰ)/Ag(Ⅰ)) under the solvothermal reaction. The results show that the cyclic Cu(Ⅰ)/Ag(Ⅰ) trimers are very stable, easily-formed and the packing modes are mainly affected by the substituents of ligands. In addition, all these complexes exhibit bright solid-state luminescence.In chapter3, five one-dimensional coordination polymers base on cyclic copper(Ⅰ) trimer units [Cu(pz)]3(Cu3) have been formed by introducing halide or pseudo-halide X into copper(I)-Hdeppz reaction systems. The Cu3units in these coordination polymers can act as bidentate angular or tridentate triangle linkers by using the peripheral pyridyl groups of the deppz ligands to further coordinate to the other metal ions, moreover, the Cu…Cu contacts exist between the Cu3units. Interestingly, the Cu3units act as π-acid to interact with halide or pseudo-halide X through intermolecular Cu…X interactions, which influence the packing modes, fluorescence emission energy and lifetimes of the complexes.In chapter4, four coordination polymers based on cyclic silver(Ⅰ) tetramer units with twelve-membered Ag4Ng metallocycle have been successfully isolated by introducing halide or pseudo-halide X into silver(Ⅰ)-Hdeppz/Hdpppz reaction systems. The silver(Ⅰ) atoms in tetramer unit are two-coordinated and deviate significantly from the ideal180°because of the Ag…X interactions, which also contribute to the formation of [Ag(pz)]4(Ag4) unit in the complexes. The Ag4Ng metallocycles are basically planar, while the Ag4units feature planar or distorted configurations, furthermore, the planar or distorted cyclic silver(I) tetramer units adopt4-connected square or4-connected tetrahedral coordination geometry to form1D/2D coordination polymers or two-folded interpenetrated3D coordination frameworks.In chapter5, a coordination polymer based on unprecedented cyclic copper(Ⅰ) tetramer units (Cu4) with twelve-membered Cu4N8metallocycle has been isolated by introducing5-methyl-tetrazole in-situ generated into CuI-Hdeppz reaction system. This original Cu4unit is a mixed-azolates tetracopper cluster with Cu4N8metallocycle, which adopts4-connected square coordination geometry to bridge Cu2I2dimers to form2D polymer. Moreover, the Cu4clusters behave as soft π-acid motifs to interact with I atoms of Cu2I2dimers from the neighboring layers through Cu…Ⅰ interactions, generating a3D supramolecular framework. In addition, the framework exhibits high thermostability and bright solid-state luminescence.