- Spectroscopic and electrochemical study of dinuclear and mononuclear copper complexes with the bidentate ligand of the 2,2′-diquinoline series
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The newly synthesized complex (2) of copper(I) chloride with di-n-hexyl 2,2'-biquinoline-4,4'-dicarboxylate (L) was spectroscopically and electrochemically characterized. The X-ray diffraction study showed that the crystals of complex 2 consist of the dinuclear moieties [L2Cu 1 2(μ-Cl)2] containing Cu 2(μ-Cl)2 clusters. Spectrophotometric studies and ESI-mass spec-trometric measurements showed that after the dissolution of complex 2 in acetonitrile (AN) and N-methyl-2-pyrrolidone (NMP), the solution contained not only the dinuclear complexes [L2Cu1 2(μ-Cl)2] but also [L2Cu1]Cl, [LCu1Cl(Sol)], and [Cu1Cl(Sol)] (Sol is the solvent). The electrochemical data also confirm the conclusion that bridged dinuclear chloride complex 2 dissociates both in NMP and AN to form the tetrahedral bis-biquinoline complex [L2Cu1]Cl. In solutions of complex 2 in alcohols and N,N-dimethylformamide (DMF), only [L2Cu1]Cl and [Cu1Cl(Sol)] are present. In EtOH, AN, and DMF, [Cu1Cl(Sol)] undergoes disproportionation to [Cu11Cl(Sol)] and Cu0.
- Vatsadze,Dolganov,Yakimanskii,Goikhman,Podeshvo,Lyssenko,Maksimov,Magdesieva
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- Biquinolino-modified β-cyclodextrin dimers and their metal complexes as efficient fluorescent sensors for the molecular recognition of steroids
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A series of bridged β-cyclodextrin (β-CyD) dimers possessing functional tethers of various lengths was synthesized in moderate yield by the treatment of 2,2′-biquinoline-4,4′-dicarboxylic dichloride with β-CyD or mono[6-oligo(ethylenediamino)-6-deoxy]-β-CyDs. The products were 2,2′-biquinoline-4,4′-dicarboxy-bridged bis(6-O-β-CyD) (8), N,N′-bis(2-aminoethyl)-2,2′-biquinoline-4,4′- dicarboxamide-bridged bis(6-amino-6-deoxy-β-CyD) (9), and N,N′-bis(5-amino-3-azapentyl)-2,2′-biquinoline-4, 4′-dicarboxamide-bridged bis(6-amino-6-deoxy-β-CyD) (10). The reaction of 8-10 with copper perchlorate give their copper(II) complexes 11-13 in satisfactory yields of over 77%. All the bis(β-CyD)s 8-13 act as efficient fluorescent sensors and display remarkable fluorescence enhancement upon addition of optically inert steroids. The inclusion complexation behaviors of 8-13 when treated with the representative steroids cholate (14), deoxycholate (15), and glycocholate (16) in aqueous solution at 25 °C were investigated by means of UV/Vis spectroscopy, conductivity and fluorescence measurements, circular dichroism spectroscopy, and 2D NMR spectroscopy. The tether length of bis(β-CyD) 9 allows it to adopt a cooperative host-tether-guest binding mode in which the spacer and guest are co-included in the two CyD cavities. As a result of this cooperation, 9 has a stability constant (Ks) about 2 × 102 times higher than that of monomodified β-CyD 4 for inclusion complexation with cholate. Metallooligo(β-CyD)s with four β-CyD units have enhanced binding abilities compared with monomodified β-CyDs. These metallo compounds have binding affinities for guest steroids that are up to 50-4.1 × 103 times higher than those of CyDs 2-4. The guest-induced fluorescence enhancement of bis(CyD)s opens a new channel for the design of sensor materials. The complex stability constants of these compounds are discussed from the viewpoint of induced-fit interaction and cooperative multiple binding between host and guest.
- Liu, Yu,Song, Yun,Chen, Yong,Li, Xue-Qing,Ding, Fei,Zhong, Rui-Qin
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- Synthesis, structure, and characterization of a new metal-organic framework containing meso-helices
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The new metal-organic framework [Cd(bqdc)(phen)]n (1) (bqdc = 2, 2'-biquinoline-4, 4'-dicarboxylate, phen = 1, 10-phenanthroline) was hydrothermally synthesized by hetero-ring carboxylate ligand and N-containing auxiliary ligand. The structure of 1 was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analyses, IR spectroscopy, X-ray powder diffraction, and TG analysis. Single-crystal X-ray structural analysis shows that complex 1 is an infinite two-dimensional framework containing aesthetic meso-helix. These two-dimensional coordination networks are interconnected through aromatic π-π stacking and C-H...O hydrogen bonding interactions to afford a 6-connected (412.6 3) three-dimensional supramolecular architecture. Furthermore, the photoluminescent property of complex 1 was studied. Copyright
- Fan, Linlin,Chen, Haiyan,Xiao, Dongrong,Wang, Enbo
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