Hydrolytic Metalloenzyme Models. Metal Ion Dependent Site-selective Acylations of Hydroxyl Groups of Bis-imidazole Ligands Promoted by Zn2+and Cu2+Ions in Cationic Micelles

The possibility of using N-allylcarbothioamide derivatives as well as products of their iodine- and proton-initiated electrophilic heterocyclizations as chelating agents in complexation reactions with Zn(II) and Ag(I) ions is shown. Processing of the obtained experimental data showed that N-allythioamides of pyrimidinyl (cyclohexenyl) carboxylic acids H2L1 – H2L3 and their proton- and iodo-cyclization products HL4, HL5 containing four nucleophilic reaction centers (two oxygen atoms of the carbonyl and hydroxyl groups and N-, S-carbothioamide groups or N-atoms of the dihydrothiazole moiety) are polydentate ligands capable of coordinating with metal ions to form stable six-membered chelate metallocycles. A series of new chelating mono-, bi- and polynuclear complexes Zn(II) and Ag (I) of the composition [Zn2L1,32]n, [Zn2(HL1-3)2(CH3COO)2], [Ag2(HL1,3)2]n, [Zn(HL1-3)2], [Ag(H2L3)2NO3], [Zn(HL4,5)2], K[Ag(HL4,5)2] were synthesized and isolated in solid state. Their molecular structure was established by methods of elemental chemical analysis, NMR 1H, IR and UV-Vis spectroscopy. At a ratio of M:L 1:2, complexes were isolated in which two ligand molecules H2L1 − H2L3 are coordinated to the metal ion by the sulfur atoms of the carbothioamide group and the oxygen of the mono-deprotonated hydroxyl group. It was established that the products of the proton-/iodocyclization HL4, HL5 in the complex formation pass into the thione tautomeric form with coordination through the oxygen atoms of the deprotonated hydroxyl group and nitrogen atoms of the dihydrothiazole heterocycle. At M:L 1:1, binuclear or polynuclear coordination compounds are formed. It was shown that polymerisation in complexes [Zn2L1,32]n and [Ag2(HL1,3)2]n is due to the formation of Zn−(O2SN)−Zn and Ag−O−Ag polymer chains. Investigation of the solubility of the resulting complexes showed that the polymer complexes are weakly soluble or insoluble in DMSO, DMF, while the mononuclear are soluble in methanol, as well as in water.

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Site-Selective Functionalization of Hydroxyl Groups in Carbohydrate Derivatives

Chemical Reviews ◽

10.1021/acs.chemrev.8b00442 ◽

2018 ◽

Vol 118 (23) ◽

pp. 11457-11517 ◽

Cited By ~ 64

Author(s):

Victoria Dimakos ◽

Mark S. Taylor

Keyword(s):

Hydroxyl Groups ◽

Selective Functionalization ◽

Site Selective

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Interaction of Alkaline Earth Metal Ions with Acetic and Lactic Acid in Aqueous Solutions Studied by 13C NMR Spectroscopy

Zeitschrift für Naturforschung A ◽

10.1515/zna-1997-0410 ◽

1997 ◽

Vol 52 (4) ◽

pp. 351-357 ◽

Cited By ~ 4

Author(s):

A. Kondoh ◽

T. Oi

Keyword(s):

Lactic Acid ◽

Nmr Spectroscopy ◽

Metal Ion ◽

Alkaline Earth ◽

Isotope Effects ◽

Earth Metal ◽

Ion Concentration ◽

Alkaline Earth Metal ◽

Hydroxyl Groups ◽

Alkaline Earth Metal Ions

Abstract Interaction of alkaline earth metal (magnesium, calcium, strontium and barium) ions with acetic and lactic acid in aqueous media was investigated by 13C NMR spectroscopy. In the acetate systems, signals whose chemical shifts were the averages of those of the free and bound acetate ions were observed. Downfield shifts of the carboxylate carbon signals with increasing metal ion concentration indicated that the acetate ion acted as a monodentate ligand coordinating to the metal ion using the carboxylate group. The metal ion concentration dependence of the peak positions of the methine and carboxylate carbon signals of the lactate ion in the lactate systems suggested that the lactate ion coordinated to a metal ion using the carboxylate and hydroxyl groups. Unique upfield shifts upon complexation in the magnesium lactate systems suggested that the lactate ion coordinated to the magnesium ion from outside the primary hydration sphere.The present results were consistent with the isotope effects of the alkaline earth metals observed in cation exchange chromatography.

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Chiral catalyst-directed site-selective functionalization of hydroxyl groups in carbohydrates

Journal of Carbohydrate Chemistry ◽

10.1080/07328303.2017.1390575 ◽

2017 ◽

Vol 36 (4-6) ◽

pp. 143-161 ◽

Cited By ~ 5

Author(s):

Wangze Song ◽

Nan Zheng

Keyword(s):

Hydroxyl Groups ◽

Chiral Catalyst ◽

Selective Functionalization ◽

Site Selective

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Modeling of neotame and fructose thermochemistry: Comparison with mono and divalent metal ions by Computational and experimental approach

Scientific Reports ◽

10.1038/s41598-019-54626-9 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Deepali Sharma ◽

Suvardhan Kanchi ◽

Ayyappa Bathinapatla ◽

Inamuddin ◽

Abdullah M. Asiri

Keyword(s):

Metal Ions ◽

Metal Ion ◽

Density Functional ◽

Divalent Metal ◽

Basis Set ◽

Hydroxyl Groups ◽

Specific Cell ◽

Water Medium ◽

Artificial Sweetener ◽

Divalent Metal Ions

AbstractThe metal complexes can demonstrate various interesting biological activities in the human body. However, the role of certain metal ions for specific cell activities is still subject to debate. This study is aimed at comparing the thermochemical properties of neotame (artificial sweetener) and α, β-fructose in gas phase and water medium. The interaction of α and β-fructose, neotame with monovalent and divalent metal ions was studied and comprehended by density functional theory (DFT) using B3LYP functional, 6–311 + G (d, p) and D3 basis set. Metal ion affinities (MIA) values depicted that ionic radius of metal ions played an important role in the interaction of α, β-fructose and neotame. The ∆G parameter was calculated to predict and understand the interaction of metal ions with α and β-fructose, neotame. The results suggested that the presence of hydroxyl groups and oxygen atoms in sugar molecules acted as preferred sites for the binding and interaction of mono and divalent ions. For the first time computational study has been introduced in the present study to review the progress in the application of metal binding with sugar molecules especially with neotame. Moreover, voltammetric behaviour of neotame-Zn2+ was studied using cyclic and differential pulse voltammetry. The obtained results suggest that the peak at −1.13 V is due to the reduction of Zn2+ in 0.1 M phosphate buffer medium at pH 5.5. Whereas, addition of 6-fold higher concentration of neotame to the ZnCl2.2H2O resulted in a new irreversible cathodic peak at −0.83, due to the reduction of neotame-Zn2+ complex. The Fourier transform infrared spectroscopy (FTIR) results indicates that the β-amino group (-NH) and carboxyl carbonyl (-C = O) groups of neotame is participating in the chelation process, which is further supported by DFT studies. The findings of this study identify the efficient chelation factors as major contributors into metal ion affinities, with promising possibilities to determine important biological processes in cell wall and glucose transmembrane transport.

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Sorption of Heavy Metal on Natural Clay

Revista de Chimie ◽

10.37358/rc.17.12.5982 ◽

2018 ◽

Vol 68 (12) ◽

pp. 2804-2807

Author(s):

Mircea Stefan ◽

Adriana Bors ◽

Daniela Simina Stefan ◽

Ionut Alexandru Savu Radu ◽

Cicerone Marinescu

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Metal Ion ◽

Background Electrolyte ◽

Hydroxyl Groups ◽

Natural Clay ◽

Equilibrium Isotherms ◽

Solution Ph ◽

Constant Ph ◽

Langmuir Isotherm Model

Sorption of heavy metals on Na-montmorillonite was studied as a function of solution pH and different concentrations of background electrolyte and also a function of added metal ion at constant pH. Equilibrium isotherms have been measured and analyzed using a Langmuir isotherm model. The metal ions were predominantly adsorbed on the permanent charge sites in a easily replaceable state. There was also evident a substantial involvement of the hydroxyl groups on the edges of Na-montmorillonite in specific adsorption of the cations especially at higher pH.

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