Hydrolysis of Methionine- and Histidine-Containing Peptides Promoted by Dinuclear Platinum(II) Complexes with Benzodiazines as Bridging Ligands: Influence of Ligand Structure on the Catalytic Ability of Platinum(II) Complexes

Bioinorganic Chemistry and Applications ◽

10.1155/2018/3294948 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Snežana Rajković ◽

Beata Warżajtis ◽

Marija D. Živković ◽

Biljana Đ. Glišić ◽

Urszula Rychlewska ◽

...

Keyword(s):

Catalytic Activity ◽

Amide Bond ◽

Spectroscopic Techniques ◽

X Ray Diffraction ◽

Bridging Ligands ◽

Metal Centers ◽

H Nmr ◽

Dinuclear Platinum ◽

Ph Range ◽

Hydrolysis Of

Dinuclear platinum(II) complexes, [{Pt(en)Cl}2(μ-qx)]Cl2·2H2O (1), [{Pt(en)Cl}2(μ-qz)](ClO4)2(2), and [{Pt(en)Cl}2(μ-phtz)]Cl2·4H2O (3), were synthesized and characterized by different spectroscopic techniques. The crystal structure of1was determined by single-crystal X-ray diffraction analysis, while the DFT M06-2X method was applied in order to optimize the structures of1–3. The chlorido Pt(II) complexes1–3were converted into the corresponding aqua species1a–3a, and their reactions with an equimolar amount of Ac–L–Met–Gly and Ac–L–His–Gly dipeptides were studied by1H NMR spectroscopy in the pH range 2.0 < pH < 2.5 at 37°C. It was found that, in all investigated reactions with the Ac–L–Met–Gly dipeptide, the cleavage of the Met–Gly amide bond had occurred, but complexes2aand3ashowed lower catalytic activity than1a. However, in the reactions with Ac–L–His–Gly dipeptide, the hydrolysis of the amide bond involving the carboxylic group of histidine was observed only with complex1a. The observed disparity in the catalytic activity of these complexes is thought to be due to different relative positioning of nitrogen atoms in the bridging qx, qz, and phtz ligands and consequent variation in the intramolecular separation of the two platinum(II) metal centers.

Download Full-text

Diorganotin(iv) benzyldithiocarbamate complexes: synthesis, characterization, and thermal and cytotoxicity study

Open Chemistry ◽

10.1515/chem-2020-0037 ◽

2020 ◽

Vol 18 (1) ◽

pp. 453-462

Author(s):

Jerry O. Adeyemi ◽

Damian C. Onwudiwe ◽

Nirasha Nundkumar ◽

Moganavelli Singh

Keyword(s):

Cell Lines ◽

Human Tumor ◽

Complexation Reaction ◽

Spectroscopic Techniques ◽

X Ray Diffraction ◽

Human Tumor Cell Lines ◽

H Nmr ◽

Cytotoxicity Studies ◽

Final Residue ◽

Mcf 7

AbstractAmmonium benzyldithiocarbamate, represented as NH4L, was prepared and used in the complexation reaction involving three organotin(iv) salts, represented as R2SnCl2 (R = CH3, C4H9, and C6H5). The structures of the synthesized complexes [(CH3)2SnL2] (1), [(C4H9)2SnL2] (2), and [(C6H5)2SnL2] (3) were established using various spectroscopic techniques (Fourier transform infrared spectroscopy, 1H NMR, 13C NMR, and 119Sn NMR) and elemental analysis. Thermal decomposition of the complexes using thermogravimetric analysis under nitrogen showed no definite pathway in the pattern of the complexes even though they are structurally related. X-ray diffraction studies of the final residue showed a common diffraction pattern for the complexes and confirmed SnS as the product of the thermal treatment. Cytotoxicity studies of these complexes against the human tumor cell lines (HeLa and MCF-7) compared favorably with the used standard 5-fluorouracil drug, with complexes 2 and 3 showing very good activity toward the used cell lines.

Download Full-text

The chemistry of N,N′-dimethylformamidine. II. Hydrolysis. Kinetically controlled formation of cis-N-methylformamide

Canadian Journal of Chemistry ◽

10.1139/v78-239 ◽

1978 ◽

Vol 56 (11) ◽

pp. 1463-1469 ◽

Cited By ~ 11

Author(s):

James D. Halliday ◽

E. Allan Symons

Keyword(s):

Aqueous Media ◽

Hydrolysis Rate ◽

Strong Base ◽

First Order ◽

H Nmr ◽

Stereoelectronic Control ◽

Pseudo First Order ◽

Ph Range ◽

Hydrolysis Of ◽

Cis Isomer

The hydrolysis of N,N′-dimethylformamidine (DMFA) has been investigated in acid and alkaline aqueous media by 1H nmr; only a narrow basic pH range could be extensively studied kinetically. The pseudo-first-order kobs rose steadily from pH 11.5 to 13.0 (reaction approximately first order in OH−), then became independent of pH above 13.5 (9.3 × 10−4 s−1 at 10 °C). In contrast to many amidines, DMFA is quite stable in acid solution (estimated value of the pseudo-first-order hydrolysis rate constant is 1.4 × 10−1 s−1 at 10 °C, pH 0.05, from measurements at 100 and 140 °C). This stability is ascribed to the difficulty of eliminating the fairly strong base methylamine from the tetrahedral intermediate in acid solution.N-Methylformamide (NMF), one of the products, is formed initially as the cis isomer. A somewhat slower conversion then occurs to the thermodynamically more stable trans isomer. This unusual result is explained in terms of Deslongchamps and co-workers' theory of stereoelectronic control for the orbital-assisted breakdown of tetrahedral intermediates.

Download Full-text

Brönsted Acidic Ionic Liquid 1-(1-Propylsulfonic)-3-methylimidazolium-Chloride Catalyzed Hydrolysisof D-Cellobiose in Aqueous Medium

International Journal of Carbohydrate Chemistry ◽

10.1155/2012/948652 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 12

Author(s):

Ananda S. Amarasekara ◽

Bernard Wiredu

Keyword(s):

Ionic Liquid ◽

Catalytic Activity ◽

Sulfuric Acid ◽

Acid Group ◽

H Nmr ◽

Acidic Ionic Liquid ◽

Brønsted Acidic Ionic Liquid ◽

Cellobiose Hydrolysis ◽

Glucose Anomers ◽

Hydrolysis Of

Brönsted acidic ionic liquid 1-(1-propylsulfonic)-3-methylimidazolium chloride (PSMIMCl) shows a higher catalytic activity than sulfuric acid in the hydrolysis of D-cellobiose to D-glucose in water at 90–120°C. This catalytic activity enhancement is more significant at higher temperatures, and at 120°C, PSMIMCl produced 64.5% glucose yield, whereas H2SO4 produced only 42.2% after 40 min. reaction, and this is a 52.8% enhancement of catalytic activity due to the alkylimidazolium group attached to the sulfonic acid group. 1H NMR monitoring of the D-cellobiose hydrolysis in PSMIMCl and sulfuric acid mediums failed to reveal intermediates in the hydrolysis reaction, and this is probably due to rapid conversion of the intermediate(s) to a mixture of D-glucose anomers with α:β≈1:1.6.

Download Full-text

Synthesis and structural analysis of polynuclear silver(I) complexes with 4,7-phenanthroline

Journal of the Serbian Chemical Society ◽

10.2298/jsc190226024s ◽

2019 ◽

Vol 84 (7) ◽

pp. 689-699 ◽

Cited By ~ 2

Author(s):

Ivana Stanojevic ◽

Nada Savic ◽

Aurélien Crochet ◽

Katharina Fromm ◽

Milos Djuran ◽

...

Keyword(s):

Solid State ◽

Room Temperature ◽

Volume Ratio ◽

Spectroscopic Techniques ◽

X Ray Diffraction ◽

X Ray ◽

Bridging Ligand ◽

Coordination Sites ◽

Hydrolysis Of

New polynuclear silver(I) complexes, [Ag(CF3SO3)(4,7-phen)(CH3CN)]n (1) and [Ag(PO2F2)(4,7-phen)]n (2), were synthesized by the reaction of 4,7-phenanthroline (4,7-phen) and the corresponding AgX salt (X = CF3SO3 - and PF6 -) in 1:2 mole ratio, respectively, in methanol/acetone (1:1 volume ratio) at room temperature. The characterization of the complexes was established on the basis of elemental microanalysis, IR and NMR (1H and 13C) spectroscopic techniques, while their crystal structures were determined by single-crystal X-ray diffraction analysis. The results of spectroscopic and crystallographic analyses revealed that in these complexes, 4,7-phen behaves as a bridging ligand between two metal ions, while the remaining coordination sites of the Ag(I) ions are occupied by the oxygen atom of CF3SO3 - and an acetonitrile nitrogen atom in 1 or by two oxygen atoms from two PO2F2 -, formed after hydrolysis of PF6 -, in 2. In the solid state, both complexes are coordination polymers in which the geometry around the Ag(I) ions is distorted tetrahedral.

Download Full-text

Hydrolysis and condensation of chlorophosphine and alkyl phosphite ligands on platinum and palladium. 31P and 195Pt nuclear magnetic resonance studies and the crystal and molecular structures of [Pt2Cl4{μ-(EtO)2POP(OEt)2}2] and [Cl2Pt{μ-(P(OEt)2O)2P(O)}PtCl(PEt3)2]

Canadian Journal of Chemistry ◽

10.1139/v86-057 ◽

1986 ◽

Vol 64 (2) ◽

pp. 343-352 ◽

Cited By ~ 10

Author(s):

David Eric Berry ◽

Kathryn Anne Beveridge ◽

Gordon William Bushnell ◽

Keith Roger Dixon ◽

Alan Pidcock

Keyword(s):

Spin Systems ◽

Molecular Structures ◽

Monoclinic Space Group ◽

X Ray Diffraction ◽

Space Group ◽

X Ray ◽

H Nmr ◽

Hydrolysis Of ◽

Related Compounds ◽

Alkyl Phosphite

Hydrolysis of cis-[PtCl2-{P(OEt)2Cl}2] results in condensation of the phosphite to form [Pt2Cl4{μ-(EtO)2POP(OEt)2}2], which crystallizes in the monoclinic space group P21/n, with a = 13.814(7), b = 11.429(4), c = 10.726(5) Å, β = 106.30(5)°. Reactions of P(OEt)2Cl or (EtO)2POP(OEt)2 with [Pt2Cl4(PEt3)2] also yield very easily hydrolyzed products but in these cases an even more complex condensation occurs to yield [Cl2Pt{(μ-(P(OEt)2O)2P(O)}PtCl(PEt3)2], which crystallizes in the monoclinic space group P21/c, a = 17.547(8), b = 19.775(6), c = 11.268(3) Å, β = 106.42(3)°. Complete X-ray diffraction studies are reported for both crystals, confirming the presence of double (EtO)2POP(OEt)2 bridges in [Pt2Cl4{(μ-(EtO)2POP(OEt)2}2] and a novel triphosphite bridge in [Cl2Pt{μ-(P(OEt)2O)2P(O)}PtCl(PEt3)2]. Detailed analyses and computer simulation of the 31P{1H} and 195Pt{1H} nmr spectra of these complexes are also described, together with studies of the related compounds, [Pt2Me4{μ-(EtO)2POP(OEt)2}2] and [Cl2(Et3P)Pt{μ-(EtO)2POP(OEt)2}PtCl2(PEt3)]. In conjunction with previous studies of [Pt2Cl2(dppm)2] and related complexes, these spectra provide examples of several types of AA′XX′ spin systems and the analysis of these systems is discussed in detail.

Download Full-text

Synthesis, Structural Characterization, and Evaluation of the Biological Properties of Heteroleptic Palladium(II) Complexes

Bioinorganic Chemistry and Applications ◽

10.1155/2014/916361 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7

Author(s):

Hizbullah Khan ◽

Nek Daraz ◽

Muhammad Nasim Khan ◽

Muhammad Said ◽

Nosheen Akhtar ◽

...

Keyword(s):

Antibacterial Activity ◽

Shigella Flexneri ◽

Dna Interaction ◽

Biological Properties ◽

Mixed Ligand ◽

Spectroscopic Techniques ◽

X Ray Diffraction ◽

X Ray ◽

H Nmr ◽

Antitumor Potential

Five heteroleptic palladium(II) complexes of the general formula Pd(PR3)(tu)Cl2, where PR3= triphenylphosphine (1), diphenyl-o-tolylphosphine (2), diphenyl-p-tolylphosphine (3), diphenyl-t-butylphosphine (4), and diphenyl-o-methoxyphenylphosphine (5), and tu = 1,3-bis(2-methoxyphenyl) thiourea. They all have been synthesized and characterized by various spectroscopic techniques (elemental analysis, FTIR, and1H NMR and the ligand 1,3-bis(2-methoxyphenyl) thiourea was synthesized by single crystal X-ray diffraction technique). The synthesized compounds were screened for their antibacterial activity against four strains of bacteria (Escherichia coli,Shigella flexneri,Staphylococcus aureus, andBacillus subtilis). The antitumor potential was evaluated in terms of activity against brine shrimp eggs and DNA interaction. The mixed ligand complexes have exhibited moderate antibacterial activity and promising antitumor potential.

Download Full-text

Hydrolysis of chlorophosphine ligands on platinum and palladium. 31P and 195Pt nmr studies and the crystal and molecular structures of cis-[PtCl2(PPh2OH)2]•C4H8O and [Pd2(µ-Cl)2{(P(OEt)2O)2H}2]

Canadian Journal of Chemistry ◽

10.1139/v85-489 ◽

1985 ◽

Vol 63 (11) ◽

pp. 2949-2957 ◽

Cited By ~ 23

Author(s):

David Eric Berry ◽

Kathryn Anne Beveridge ◽

Gordon William Bushnell ◽

Keith Roger Dixon

Keyword(s):

Molecular Structures ◽

Monoclinic Space Group ◽

X Ray Diffraction ◽

Nmr Studies ◽

Space Group ◽

X Ray ◽

H Nmr ◽

Hydrolysis Products ◽

Hydrolysis Of ◽

Controlled Hydrolysis

Controlled hydrolysis of cis-[PtCl2(PPh2Cl)2] gives cis-[PtCl2(PPh2OH)2] which crystallizes as a tetrahydrofuran solvate in the monoclinic space group P21/n, with a = 14.647(3), b = 15.089(3), c = 13.107(2) Å, β = 91.22(3)°. This is the first example of a complex containing a cis-M(PR2OH)2 group to be structurally characterized since further reaction to [Formula: see text] ligand systems is the more usual outcome of such hydrolyses. An example of the latter type, [Pd2(μ-Cl)2-{(P(OEt)2O)2H}2], crystallizes in the monoclinic space group P21/c, a = 9.674(2), b = 20.722(5), c = 8.578(2) Å, β = 92.75(3)°. Complete X-ray diffraction studies are reported for both crystals. Synthesis and 31P{1H} and 195Pt{1H} nmr studies are reported for the complexes [PtCl2(PEt3)(PR2Cl)], R = OEt, Ph, Cy, Et, or Bu′, which have cis stereochemistry except when R = Bu′, and for cis-[PtCl2(PR2Cl)2], R = OEt, Ph, or Et, and also for the hydrolysis products, cis-[PtCl2(PEt3)(PR2OH)], R = OEt or Ph, and cis-[PtCl2(PR2OH)2], R = OEt, Ph, or Et. Analogous products for palladium are generally less stable and more difficult to characterize. The complex of products from hydrolysis of palladium/P(OEt)2Cl compounds is discussed in detail.

Download Full-text

Selective Formation, Reactivity, Redox and Magnetic Properties of MnIII and FeIII Dinuclear Complexes with Shortened Salen-Type Schiff Base Ligands

International Journal of Molecular Sciences ◽

10.3390/ijms21217882 ◽

2020 ◽

Vol 21 (21) ◽

pp. 7882

Author(s):

Luca Rigamonti ◽

Paolo Zardi ◽

Stefano Carlino ◽

Francesco Demartin ◽

Carlo Castellano ◽

...

Keyword(s):

Mixed Valence ◽

Coupling Constants ◽

Dinuclear Complexes ◽

X Ray Diffraction ◽

Schiff Base Ligands ◽

Bridging Ligands ◽

Metal Centers ◽

Bond Breakage ◽

Dinuclear Compounds ◽

Selective Formation

The reactivity of the shortened salen-type ligands H3salmp, H2salmen and H2sal(p-X)ben with variable para-substituent on the central aromatic ring (X = tBu, Me, H, F, Cl, CF3, NO2) towards the trivalent metal ions manganese(III) and iron(III) is presented. The selective formation of the dinuclear complexes [M2(μ-salmp)2], M = Mn (1a), Fe (2a), [M2(μ-salmen)2(μ-OR)2)], R = Et, Me, H and M = Mn (3a–c) or Fe (4a–c), and (M2(μ-sal[p-X]ben)2(μ-OMe)2), X = tBu, Me, H, F, Cl, CF3, NO2 and M = Mn (5a–g) or Fe (6a–g), could be identified by reaction of the Schiff bases with metal salts and the base NEt3, and their characterization through elemental analysis, infrared spectroscopy, mass spectrometry and single-crystal X-ray diffraction of 2a·2AcOEt, 2a·2CH3CN and 3c·2DMF was performed. In the case of iron(III) and H3salmp, when using NaOH as a base instead of NEt3, the dinuclear complexes [Fe2(μ-salmp)(μ-OR)(salim)2], R = Me, H (2b,c) could be isolated and spectroscopically characterized, including the crystal structure of 2b·1.5H2O, which showed that rupture of one salmp3− to two coordinated salim− ligands and release of one salH molecule occurred. The same hydrolytic tendency could be identified with sal(p-X)ben ligands in the case of iron(III) also by using NEt3 or upon standing in solution, while manganese(III) did not promote such a C–N bond breakage. Cyclic voltammetry studies were performed for 3b, 4b, 5a and 6a, revealing that the iron(III) complexes can be irreversibly reduced to the mixed-valence FeIIFeIII and FeII2 dinuclear species, while the manganese(III) derivatives can be reversibly oxidized to either the mixed-valence MnIIIMnIV or to the MnIV2 dinuclear species. The super-exchange interaction between the metal centers, mediated by the bridging ligands, resulted in being antiferromagnetic (AFM) for the selected dinuclear compounds 3b, 4b, 5a, 5e,5f, 6a and 6e. The coupling constants J (–2JŜ1·Ŝ2 formalism) had values around −13 cm−1 for manganese(III) compounds, among the largest AFM coupling constants reported so far for dinuclear MnIII2 derivatives, while values between −3 and −10 cm−1 were obtained for iron(III) compounds.

Download Full-text

Study on Mesoporous PW/SBA-15 for Isomerization of α-Pinene

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.483.134 ◽

2013 ◽

Vol 483 ◽

pp. 134-137 ◽

Cited By ~ 7

Author(s):

Chun Hua Wu ◽

Hui Qing Liu ◽

Chang Fu Zhuang ◽

Guan Ben Du

Keyword(s):

Catalytic Activity ◽

Phosphotungstic Acid ◽

Spectroscopic Techniques ◽

Framework Structure ◽

X Ray Diffraction ◽

Hydrothermal Conditions ◽

Ph Adjustment ◽

X Ray ◽

Transmission Electron ◽

Silicate Framework

SBA-15 supported phosphotungstic acid has been synthesized under hydrothermal conditions via pH adjustment and characterized with various analytical and spectroscopic techniques including X-ray diffraction (XRD), N2 adsorption, transmission electron micrographs (TEM). XRD results indicate that the substitution of tungsten occurs in the silicate framework structure of SBA-15. Study on the catalytic activity of mesoporous PW/SBA-15 catalyst through the isomerization of the a-pinene was investigated. The best reactive conditions of a-pinene isomerization were follows: reaction temperature 130°C, dosage of PW/SBA-15 catalyst 2 %, reactive time 2 h. Then the rate of a-pinene conversion could achieve 94.56 %, the selectivity of camphene could achieve 48.5%.

Download Full-text