2-Pyridinyl-2-pyrazinylmethanone (L4) is able to exist in the neat ketone form and gem-diol form (2-C5H4N)C(OH) 2(2-C4H3N2) (L4a) in its Ag(I) and Cu(II) complexes. Two isostructural Cu(II) complexes [Cu(L4 a)2X2·2H2O, X = C lO4-, BF4-] with the L4a ligand taking the chelating mode are formed, in which the different linkage modes of lattice water molecules between the Cu(L4 a)22+ units lead to different space groups in crystallization. Through versatile anion-pi(pyrazinyl ring) and hydrogen-bonding interactions, the Cu(L4a)22+ units are assembled into distinct 3-D metal-organic hybrid frameworks in these two complexes. Different ligation modes of L4 in its neat ketone and gem-diol forms are found in its silver(I) complexes that exhibit diverse network structures. / By tuning the counter anion, mu2-bridging 2,6-pyridinediylbis(4-pyridinyl)methanone (L2) via two terminal 4-pyridyl N atoms links Ag(I) ions into two distinct structural motifs in its silver(I) complexes, namely infinite helical chain and metallacyclophane, which are further assembled into higher-dimensional metal-organic frameworks through Ag···Ag, pi···pi, hydrogen-bonding, Ag···O=C, carbonyl···carbonyl, as well as unconventional anion-pi(pyridyl ring) interactions. Intermolecular dipolar carbonyl···carbonyl interaction of three principal types serves as a common dominant non-covalent interaction in the supramolecular conglomeration of these complexes. / Di-2-pyrazinylmethanone (L3) readily undergoes metal-assisted hydration reaction in its Ag(I), Cu(II), Co(II) and Cd(II) complexes, and is potentially useful for the construction of extended coordination networks with its gem-diol (2-C4H3N2)2C(OH) 2 (L3a) or anionic (2-C4H3N 2)2C(OH)CO- (L3b) form as an architectural moiety. A sheet-like net, an alpha-polonium topology of the NaCl-type and a rare 1-D nanotubular coordination architecture has been generated in its Ag(I) complexes through the tuning of counter-anions. Three isostructural complexes Cu(L3a)2X2· nH2O (n = 4.5; X = ClO 4-, BF4-, PF 6-) have been obtained and characterized. The 3-D host frameworks of these complexes are constructed from the linkage of mononuclear Cu(L3a)22+ metallotectons through a combination of hydrogen-bonding and anion-pi interactions, leading to honeycomb-like channels that accommodate guest water molecules. A cubane-like Co(II) cluster stabilized by L3b and the topological structure of Cd(II) complexes with L3a have also been obtained. / Di-2-pyridinylmethanone (di-2-pyridyl ketone) is a well-known versatile ligand among the basic building blocks for the construction of metal-organic hybrid materials. It can exist in its neat form, or in the hydrated gem-diol and alcoholated hemiketal forms. In this thesis, through modification of the heterocyclic ring and the bridging functional group, we have systematically synthesized a series of transition metal complexes of five carbonyl-bridged heterocycles (L1-L5) (see P. xi) and two structural analogs with sulfinyl and sulfonyl bridging groups (L6-L7), which are expected to provide flexible coordination bonding and additional non-covalent interactions in the generation of metal-organic hybrid frameworks. / In the two mononuclear Cu(II) complexes of 2,6-pyridinediylbis(3-pyridinyl)methanone (L1) with the ligand taking a chelating mode, four distinct types of unconventional intermolecular C=O···pi interactions between the carbonyl and pyridyl rings were identified. Moreover, the mu2-bridging L1 via two 3-pyridyl N atoms proves to be an excellent building block for the construction of disilver(I) metallacyclophanes with a [Ag2(L1) 2]2+ skeleton in a series silver(I) complexes. The [Ag 2(L1)2]2+ metallacycle functions as a secondary building unit to form infinite chains through Ag···O=C or argentophilic interactions, which are further assembled into a 3-D supramolecular structure via collective weak interactions including the anion-pi interaction. The employment of different Cd(II) and Hg(II) salts to react with the flexible L1 ligand has resulted in infinite chain, mononuclear, and 3-D network structures, in which L1 takes eta1-terminal, N,N-chelating, and mu2- and mu3-bridging modes. In these complexes, C--H···O, C--H···Cl--M hydrogen bonding, pi···pi, carbonyl···carbonyl, O(perchlorate)···C=O, as well as unconventional anion···pi(pyridyl ring) interactions, play important roles in consolidation of the supramolecular frameworks. / Sulfinyldipyrazine (L7) is capable of forming intriguing architectures in various sivler(I) salts, including a series of coordination polymers exhibiting (4,4) net, infinite chain and 3-D framework structures. A remarkable characteristic of L7 is that the electron-deficient pyrazinyl ring and the sulfonyl group provide potential bonding sites for lone-pair-aromatic interactions in the supramolecular assemblies, such as anion-pi and S=O···pi(pyrazinyl ring) interactions. The S=O moiety of the sulfonyl group exhibits an affinity for the pyrazinyl ring, which is evidenced by the existence of two types of such interaction in the silver(I) complexes of L7. (Abstract shortened by UMI.) / by Wan, Chongqing. / Adviser: Thomas C. W. Mak. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3504. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 172-190). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344270 |
| Date | January 2008 |
| Contributors | Wan, Chongqing., Chinese University of Hong Kong Graduate School. Division of Chemistry. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xiii, 202 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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