10380-28-6Relevant articles and documents
Solution Chemistry of Copper(II) Binding to Substituted 8-Hydroxyquinolines
Dolgova, Natalia V.,George, Graham N.,Harris, Hugh H.,James, Ashley K.,Kroll, Thomas,Pickering, Ingrid J.,Pushie, M. Jake,Sokaras, Dimosthenis,Sopasis, George J.,Summers, Kelly L.
, p. 13858 - 13874 (2020)
8-Hydroxyquinolines (8HQs) are a family of lipophilic metal ion chelators that have been used in a range of analytical and pharmaceutical applications over the last 100 years. More recently, CQ (clioquinol; 5-chloro-7-iodo-8-hydroxyquinoline) and PBT2 (5,7-dichloro-2-[(dimethylamino)methyl]-8-hydroxyquinoline) have undergone clinical trials for the treatment of Alzheimer's disease and Huntington's disease. Because CQ and PBT2 appear to redistribute metals into cells, these compounds have been redefined as copper and zinc ionophores. Despite the attention surrounding the clinical trials and the clear link between 8HQs and metals, the fundamental solution chemistry of how these compounds bind divalent metals such as copper and zinc, as well as their mechanism(s) of action in mammalian systems, remains poorly understood. In this study, we used a combination of X-ray absorption spectroscopy (XAS), high-energy resolution fluorescence detected (HERFD) XAS, electron paramagnetic resonance (EPR), and UV-visible absorption spectroscopies to investigate the aqueous solution chemistry of a range of 8HQ derivatives. To circumvent the known solubility issues with 8HQ compounds and their complexes with Cu(II), and to avoid the use of abiological organic solvents, we have devised a surfactant buffer system to investigate these Cu(II) complexes in aqueous solution. Our study comprises the first comprehensive investigation of the Cu(II) complexes formed with many 8HQs of interest in aqueous solution, and it provides the first structural information on some of these complexes. We find that halogen substitutions in 8HQ derivatives appear to have little effect on the Cu(II) coordination environment; 5,7-dihalogenated 8HQ conformers all have a pseudo square planar Cu(II) bound by two quinolin-8-olate anions, in agreement with previous studies. Conversely, substituents in the 2-position of the 8HQ moiety appear to cause significant distortions from the typical square-planar-like coordination of most Cu(II)-bis-8HQ complexes, such that the 8HQ moieties in the Cu(II)-bis-8HQ complex are rotated approximately 30-40° apart in a propeller-like arrangement.
Fleck, H. R.,Ward, A. M.
, p. 388 - 395 (1933)
Immobilization of Cu-chelate onto SBA-15 for partial oxidation of benzyl alcohol using water as the solvent
Hu, Jing,Zou, Yongcun,Liu, Jing,Sun, Jian,Yang, Xiaoyuan,Kan, Qiubin,Guan, Jingqi
, p. 5703 - 5712 (2015)
Bis(8-quinolinolato)copper(II) complex immobilized onto SBA-15 catalyst has been synthesized through a stepwise procedure. The characterization results indicated that the BET surface area, total pore volume, and average pore width decrease after stepwise modification of SBA-15, while the structure stays intact. Catalytic tests showed that CuQ2-SBA-15 catalyzes the oxidation reaction well with 32.5 % conversion of benzyl alcohol and 81.8 % selectivity to benzaldehyde when water is used as the solvent. In addition, homogeneous catalyst bis(8-quinolinolato)copper(II) exhibits very bad catalytic behavior using water as the solvent.
Xin, Xin-Quan,Zheng, Li-Min
, p. 451 - 460 (1993)
Skraup, H.
, (1882)
Abou Sekkina, Morsi M.,El-Helbaway, S. M.
, p. 223 - 230 (1984)
Moeller, T.
, p. 346 - 349 (1943)
Heteroleptic complexes: Via solubility control: Examples of Cu(ii), Co(ii), Ni(ii) and Mn(ii) complexes based on the derivatives of terpyridine and hydroxyquinoline
Baskin, Maria,Fridman, Natalia,Kosa, Monica,Maayan, Galia
supporting information, p. 15330 - 15339 (2017/11/22)
We describe the construction of synthetically challenging heteroleptic complexes by capitalizing on the solubility properties of their corresponding favored homoleptic complexes. We demonstrate that the formation of a heteroleptic Cu2+ complex based on 2,2′:6′,2′′-terpyridine (Terpy) and 8-hydroxyquinoline (HQ) is not possible due to the insolubility of (HQ)2Cu2+. Replacing HQ with 8-hydroxy-2-quinolinecarbonitrile (HQCN) enabled the solubility of (HQCN)2Cu2+ in acetonitrile, leading to the formation of the heteroleptic complex Terpy(HQCN)Cu2+, TQCu. Applying these conditions to the synthesis of the corresponding heteroleptic Co2+ complex resulted in TerpyCo2+(acetate)2, which is insoluble in acetonitrile. Upon changing the solvent to methanol, the carbonitrile group of HQCN was converted to carboxyimidate HQOMe yielding a heteroleptic complex Terpy(HQOMe)Co2+, TQ′Co. Using this method, we also generated the heteroleptic complex TQ′Ni and the polynuclear heteroleptic complex Q′4Q′′2Mn4 (Q′′ = HQO2Me). Detailed analysis of the complexes included characterization by X-ray diffraction, EPR, UV-Vis, high resolution ESI MS, DFT calculations and electrochemistry. X-ray analysis of TQCu revealed distorted square pyramidal geometry, while TQ′Co and TQ′Ni exhibit distorted octahedral geometry, which includes metal coordination via the carboxyimidate nitrogen site. Interestingly, Q′4Q′′2Mn4 was found to contain a [MnII4(μ3-O)2(μ2-O)4N10]2+ core, which adopts a distorted octahedral geometry, and two types of HQ chelators. Thus, Q′4Q′′2Mn4 is also heteroleptic even though it does not contain a Terpy ligand. Solution studies revealed that while TQCu is stable in solution, TQ′Co and TQ′Ni go through ligand exchange and are partially converted to their corresponding homoleptic complexes. Based on these data we could propose a mechanism for the formation of TQ′Co and TQ′Ni and show that TQ′Co can be prepared directly from Terpy and HQOMe.
