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1.
The properties of isothiocyanato(3-thiapentane-1,5-dithiolato)oxorhenium(V) [ReO(SSS)NCS, (1a), (3+1) type], where isothiocyanato occupies the fifth position, have been studied. Two linkage isomers, i.e., ReO(SSS)NCS (1a) and ReO(SSS)SCN (1b), were found to be formed during syntheses. The sufficient quantities of 1a were isolated in the solid state, and characterized by X-ray crystallography and IR spectroscopy. From 1H and 15N NMR measurements, it was found that 1a is in equilibrium with 1b in liquid state. In the solvents with low dielectric constant such as CH2Cl2, only 1a isomer was detected, while in the solvents with high such as CH3CN, both 1a and 1b isomers were observed. We have obtained the equilibrium constant (Kiso) for the linkage isomerization reaction in CD3CN by measuring 15N NMR spectra at various temperatures. The values of Kiso at 25 °C, the standard enthalpy (ΔH°), and the standard entropy (ΔS°) for the isomerization equilibrium were evaluated as 0.409, 14.4 kJ mol−1, and 40.9 J K−1 mol−1, respectively.  相似文献   

2.
Reactions of chloro(3-thiapentane-1,5-dithiolato)oxorhenium(V) [ReO(SSS)Cl] with N-methyl-1H-imidazole-2-thiol (HL1) and 2-pyrimidinethiol (HL2) have been studied to form ‘3+1’ oxorhenium(V) complexes. In the absence of triethylamine, [Re(SSS)(HL1)]Cl (1a) was formed, while in the presence of triethylamine [Re(SSS)L1] (1b) and [Re(SSS)L2] (2) were produced. Molecular structures of complexes 1a and 2 were determined to be distorted square pyramidal by single crystal X-ray analytical method. From cyclic voltammetric studies, furthermore, it was proposed that complexes 1b and 2 are irreversibly oxidized to Re(VI) at around 0.84 and 1.01 V versus Ag/AgNO3, respectively, and are reduced to Re(IV) at −1.55 and −1.51 V with the dissociation of L1 or L2, followed by the quasi-reversible reductions to Re(III) at around −1.69 V, respectively.  相似文献   

3.
Ligand exchange reactions of oxorhenium(V) precursors with bidentate SN and tridentate Schiff bases derived from the condensation of ketones or aldehydes with dithiocarbazic acid methyl ester (H2NNHC(S)SCH3) produce novel ‘3+2’ mixed-ligand complexes carrying the SNO/SN donor atom set. Thus, reactions of either [NBu4][ReOCl4] or Na[ReO(Gluconate)2] with SNO ligands (H2Ln) or a mixture of bidentate SN (HLm) and tridentate SNO (H2Ln) in methanol solutions lead, respectively, to the six-coordinated mixed ligand oxorhenium(V) compounds of types [ReO(Ln)(HLn)] and [ReO(Ln)(Lm)], combining one tridentate dianionic SNO donor Schiff base (L) and one bidentate anionic SN donor ligand (HL). Coordination geometry around rhenium is distorted octahedral with the two SN donor atom sets of each ligand defining the equatorial plane, while apical positions are occupied by the oxo group and the oxygen atom of the tridentate SNO ligand (L), as shown by single-crystal X-ray diffraction structure of [ReO(L1)(HL1)] 1.  相似文献   

4.
Mixed ligand ruthenium(II) complexes containing an amino acid (AA) and 1,10-phenanthroline (phen), i.e. [Ru(AA)(phen)2]n+ (n=1,2, AA=glycine (gly), l-alanine (l-ala), l-arginine (l-arg)) have been synthesized. The interactions of these complexes and [Ru(phen)3]2+ with DNA have been examined by absorption, luminescence, and circular dichroism spectroscopic methods. Absorption spectral properties revealed that [Ru(AA)(phen)2]+ (AA=gly, l-ala) interacted with CT-DNA by the electrostatic binding mode. [Ru(l-arg)(phen)2]2+ exhibited the greatest hypochromicity, red shift, and binding constant, indicating that this complex may partially intercalate into the base-pairs of DNA. These results were also suggested by luminescence spectroscopy. CD spectral properties have been examined to understand the detailed interactions of the ruthenium(II) complexes with artificial DNA. In the case of Δ-[Ru(l-arg)(phen)2]2+, the solution on adding [poly(dG-dC)]2 exhibited two well-defined positive peaks, which the shorter and longer wavelength peaks were assigned as originating from the major and the minor groove binding modes, respectively. Then, the solution on adding [poly(dA-dT)]2 exhibited only one positive peak, which was assigned as a peak corresponding to the minor groove binding mode.  相似文献   

5.
New molybdenum complexes were prepared by the reaction of [MoVIO2(acac)2] or (NH4)2[MoVOCl5] with different N-substituted pyridoxal thiosemicarbazone ligands (H2L1 = pyridoxal 4-phenylthiosemicarbazone; H2L2 = pyridoxal 4-methylthiosemicarbazone, H2L3 = pyridoxal thiosemicarbazone). The investigation of monomeric [MoO2L1(CH3OH)] or polymeric [MoO2L1-3] molybdenum(VI) complexes revealed that molybdenum is coordinated with a tridentate doubly-deprotonated ligand. In the oxomolybdenum(V) complexes [MoOCl2(HL1-3)] the pyridoxal thiosemicarbazonato ligands are tridentate mono-deprotonated. Crystal and molecular structures of molybdenum(VI) [MoO2L1(CH3OH)]·CH3OH, and molybdenum(V) complexes [MoOCl2(HL1)]·C2H5OH, as well as of the pyridoxal thiosemicarbazone ligand methanol solvate H2L3·MeOH, were determined by the single crystal X-ray diffraction method.  相似文献   

6.
A (1 → 3)-β-glucan 3-glucanohydrolase (EC 3.2.1.39) has been purified approx. 190-fold from extracts of germinating barley. The enzyme has an apparent Mr 32 000, a pI of 8.6, and a pH optimum of 5.6. Analysis of hydrolysis products released from the (1 → 3)-β-glucan, laminarin, shows that the enzyme is an endohydrolase. Sequence analysis of the 46 NH2-terminal amino acids of the (1 → 3)-β-glucanase reveals 54% positional identity with barley (1 → 3,1 → 4)-β-glucanases (EC 3.2.1.73) and suggests a common evolutionary origin for these two classes of β-glucan endohydrolases. The barley (1 → 3)-β-glucanase also exhibits significant similarity with a (1 → 3)-β-glucanase from tobacco.  相似文献   

7.
In our efforts to investigate the factors that affect the formation of coordination architectures, such as secondary coordination donors and pendant skeletons of the carboxylic acid ligands, as well as H-bonding and other weak interactions, two kinds of ligands: (a) 3-(2-pyridyl)pyrazole (L1) with a non-coordinated N atom as a H-bonding donor, a 2,2′-bipyridyl-like chelating ligand, and (b) four carboxylic ligands with different secondary coordination donors and/or pendant skeletons, 1,4-benzenedicarboxylic acid (H2L2), 4-sulfobenzoic acid (H2L3), quinoline-4-carboxylic acid (HL4) and fumaric acid (H2L5), have been selected to react with Mn(II) salts, and five new complexes, [Mn(L1)2(SO4)]2 (1), [Mn(L1)2(L2)] (2), [Mn(L1)(HL3)2] (3), Mn(L1)2(L4)2 (4), and [Mn(L1)2(L5)] (5), have been obtained and structurally characterized. The structural differences of 1-5 can be attributed to the introduction of the different carboxylic acid ligands (H2L2, H2L3, HL4, and H2L5) with different secondary coordination donors and pendant skeletons, respectively. This result also reveals that the typical H-bonding (i.e. N-H?O and O-H?O) and some other intra- or inter-molecular weak interactions, such as C-H?O weak H-bonding and π?π interactions, often play important roles in the formation of supramolecular aggregates, especially in the aspect of linking the multi-nuclear discrete subunits or low-dimensional entities into high-dimensional supramolecular networks.  相似文献   

8.
Three new coordination complexes [Mn(L)(H2O)2](1,4-BDC)·2H2O (1), [Mn(L)0.5(1,4-BDC)]CH3OH·H2O (2) and [Mn(L)(H2O)2](1,2-HBDC)2·2H2O (3) were synthesized by solvothermal reactions of 1,2,4,5-tetrakis(imidazol-1-ylmethyl)benzene (L) and 1,4-benzenedicarboxylic acid (1,4-H2BDC) or 1,2-benzenedicarboxylic acid (1,2-H2BDC) with Mn(II) salt, and characterized by single crystal X-ray diffraction, IR, thermogravimetric and elemental analyses. In complexes 1 and 3, each ligand L links four Mn(II) atoms to form two-dimensional (2D) cationic network with non-coordinated 1,4-BDC2− and 1,2-HBDC anions lying in the voids between the two adjacent layers, respectively. The 2D layers are further connected together by hydrogen bonds to give three-dimensional (3D) supramolecular structures. However, the 1,4-BDC2− in 2 acts not only as counteranion, but also as bridging ligand leading to the formation of 2-fold interpenetrated 3D framework with pcu (primitive cubic unit) topology. The Mn(II) atoms bridged by carboxylate groups in 2 show antiferromagnetic interactions.  相似文献   

9.
All seven possible bradykinin (BK) analogs containing Aib in place of proline have been synthesized by the solid phase method and assayed for in vitro myotropic activity on the guinea pig ileum and rat uterus, and in vivo on the rat blood pressure, both by intravenous and intra-aortic administration. [Aib2,3]-BK, [Aib2,7]-BK, and [Aib2,3,7]-BK had no in vivo or in vitro activities; [Aib2]-BK, [Aib3]-BK and [Aib3,7]-BK had moderate BK-like activities and a significantly increased resistance to pulmonary inactivation in the rat ([Aib3,7]-BK was totally resistant). [Aib7]-BK was found to be the most active position seven BK analog yet assayed on the rat blood pressure, and shows remarkably high ileum (4 times BK) and intravenous rat blood pressure (6 times BK) activity.  相似文献   

10.
Using vanadate, poly(1H-pyrazol-1-yl)borate and pyrazole as starting materials, two new neutral peroxovanadium(V) complexes with poly(1H-pyrazol-1-yl)borate, VO(O(2))(pzH)(HB(pz)(3))(1) and VO(O(2))(pzH)(B(pz)(4))(2), were synthesized successfully. Both complexes were characterized by elemental analysis, IR, UV-vis and NMR spectra. And the structure of complex 1 was determined by X-ray diffraction, which is somewhat relevant for haloperoxidase enzymes. Cytotoxic effects also are discussed on 3T3 cell proliferation. In the concentration range (0.1-100mumol), both complexes have an inhibiting cellular proliferation effect. When the cells cultivated with the complexes at high dose, the toxicity effect of both complexes is more and more predominant.  相似文献   

11.
Four pentacoordinated square-pyramidal Cu(II) complexes with the general formula [Cu(L)(X)], where L is a l-histidine derived tetradentate ligand and X is either 3-hydroxypyridine or 2-methylpyridine, has been synthesized. Structural analysis showed that the presence of water filled one dimensional chiral channel in the lattices. The interiors of the channels were varied using aromatic ring substitution on the ligand as well as on the monodentate ligand. The dimensions of the channels range from ∼7 to 9 Å.  相似文献   

12.
A series of organotin(IV) complexes with Schiff base ligand pyruvic acid 3-hydroxy-2-naphthoyl hydrazone [R2SnLY]2, L = 3-HO-C10H6-2-CONHNC(CH3)COOH, R = n-C4H9, Y = CH3OH (1), R = n-C4H9, Y = N (2), R = PhCH2 (3), R = Ph, Y = CH3OH (4), R = Me, (5) and [R3SnLY], L = 3-HO-C10H6-2-CONHNC(CH3)COOH, R = n-C4H9, Y = H2O, (6), R = Ph (7), R = Me (8) have been synthesized. These complexes have been characterized by elemental analysis, IR, 1H and 119Sn NMR spectra. The crystal and molecular structure of complexes 1, 2 and 6 have been determined by X-ray single crystal diffraction. Results showed that complex 1 has a dimeric structure and the central tin atom is rendered seven-coordinate in a distorted pentagonal-bipyramid configuration. The complex 2 has a monoclinic structure and the central tin atom is rendered six-coordinate in octahedrally configuration with a planar of SnO3N unit and two apical aryl C atoms. And the whole structure consists of molecular units connected by weak intermolecular Sn?N and O-H?N interactions. In the complex 6, the central tin atom is five-coordinate in distorted trigonal-bipyramidal geometry.  相似文献   

13.
Three new complexes [Cu(L)(2)(NO(3))](NO(3))(H(2)O)(1/2)(CH(3)OH)(1/2) (1), [Cd(L)(2)(NO(3))(2)](H(2)O)(3) (2) and [Cd(L)(2)(ClO(4))(CH(3)OH)](ClO(4))(H(2)O)(1/4)(CH(3)OH) (3) (L=1-[3-(2-pyridyl)pyrazol-1-ylmethyl]naphthalene) were synthesized and characterized by elemental analyses, IR and X-ray diffraction analysis. Among them, the Cu(II) and Cd(II) ions were both coordinated by four N donors from two distinct L ligands via N,N-bidentate chelating coordination mode. Additional weak interactions, such as the face-to-face pi-pi stacking and C-Hcdots, three dots, centeredO H-bonding interactions, linked the mononuclear unit into 1D chain and further into 2D network. Complexes 1-3 were subjected to biological assays in vitro against six different cancer cell lines. All of them exhibited cytotoxic specificity and notable cancer cell inhibitory rate. The interactions of 1-3 with calf thymus DNA were investigated by thermal denaturation, viscosity measurements, spectrophotometric and electrophoresis methods. The results indicate that these complexes bound to DNA by intercalation mode via the ligand L and had different nuclease activities, which were in good agreement with their DNA-binding strength. Moreover, the central metal ions of 1-3 played a vital role in DNA-binding behaviors, DNA-cleavage activities and cytotoxicities, whereas the contribution of the different counter anions to their bioactivities also should not be ignored.  相似文献   

14.
2-[Bis(ethoxyethyl)phosphino]phenol P1-OH reacts in basic refluxing solvents with ReOCl3(PPh3)2, in a 2/1 molar ratio, to give the green ReOCl(P1-O)2 complex. Structure elucidation by 31P NMR is consistent with a cis-PP “twisted” octahedral complex, which is the preferred conformation on electronic grounds. The complex is unique in toluene while several species were present in ethanol. When the reaction is performed with Re(NPh)Cl3(PPh3)2, a mixture of trans-PP (major) and cis-PP(minor) species in a 3/1 ratio is obtained. These geometric isomers were distinguished by their 2JPP coupling constants. Only cis-PP-Re(NPh)Cl(P1-O)2, less soluble, could be isolated and its molecular structure determined by physicochemical measurements. This is the first example of cis-PP phosphinophenolato complex with the [ReNPh]3+ core, thus illustrating the importance of the steric demand of the phosphine substituent. Reaction of P1-OH with NiCl2 gives Ni(P1-O)2 as an orange oily solid with a cis-PP square planar structure. This structure is the most probable based on the 31P, 13C NMR data.  相似文献   

15.
The reaction of cobalt(II) chloride with a new class of thiosemicarbazones viz; cis-3,7-dimethyl-2,6-octadienthiosemicarbazone(CDOTSC; L1H) and 3,7-dimethyl-6-octenethiosemicarbazone (DOTSC; L2H) and N-phthaloyl derivative of DL-glycine(A1H), L-alanine(A2H) or L-valine(A3H) in 1:1:1 molar ratio in dry refluxing ethanol have been studied. All the isolated complexes have the general composition [Co(L)(A)]. Tentative structures are proposed for these complexes based upon elemental analysis, electrical conductances, magnetic moment, molecular weight determination and spectral (IR, electronic) studies.The ligands and Co(II) complexes have been tested for their antibacterial and antifungal activities against three bacterial strains S. aureus, B. subtilis, E. coli and two fungal strains F. moniliformae and M. phaseolina. Attempts have been made to establish a correlation between the antibacterial and antifungal activity and the structures of products.  相似文献   

16.
In this study, the effects of four novel mononuclear palladium(II) and platinum(II) complexes on the activity of human serum paraoxanase1 were examined. First, four novel mononuclear palladium(II) and platinum(II) complexes were synthesized with a nitrogen donor ligand 1‐(2‐aminoethyl)pyrrolidine and nonsteroidal anti‐inflammatory drugs diclofenac, mefenamic acid. These complexes were characterized by spectroscopic, thermal, and elemental analyses. The crystal structures of complex [Pd(2‐amepyr)2](dicl)2 1 and [Pd(2‐amepyr)2](mef)2 3 were determined by X‐ray crystallography. Then, paraoxonase1 enzyme was purified from human serum. The effects of these complexes on enzyme were evaluated in vitro. The complexes consist of the cationic unit and the counterions. The diclofenac and mefenamic acid acted as a counterion in the complexes. It was observed that all the complexes were stable up to high temperatures. These complexes, even at low doses, inhibited the activity of the enzyme with different inhibition mechanisms.  相似文献   

17.
To investigate the structure-activity relationship of vanadium complexes in inhibiting protein tyrosine phosphatase1B (PTP1B), eight mixed-ligand oxovanadium(IV) complexes, [VIVO(SalAla)(NN)] (H2SalAla for salicylidene alanine, NN for N,N′-donor heterocyclic base, namely, 2,2′-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq, 3), dipyrido[3,2-a:2′,3′-c]phenazine (dppz, 4)), [VIVO(SalLys)(dpq)] (5), [VIVO(SalLys)(dppz)] (6), [VIVO(SalAsp)(dppz)], (7) and [VIVO(SalTrp)(dppz)] (8)), of which 3-8 are new, have been prepared and characterized by elemental analysis, infrared, UV-visible, electrospray ionization mass spectrometry and conductivity. The molar conductance data confirmed the non-electrolytic nature of the complexes in DMSO solution. The coordination in [VIVO (SalAla)(phen)] (2) was confirmed by X-ray crystal structure analysis. The oxidation state of V(IV) with d1 configuration in 2 was confirmed by EPR. The speciation of VO-SalAla-phen in aqueous solution was investigated by potentiometric pH titrations. The results indicate that the main species are two ternary complexes at the pH range 7.0-7.4. Biochemical assays demonstrate that the mixed-ligand oxovanadium(IV) complexes are potent inhibitors of PTP1B with IC50 values in the range of 62-597 nM, approximately 3-10 fold weaker in potency than those of similar mixed-ligand oxovanadium(IV) complexes of salicylidene anthranilic acid (SAA) derivative with polypyridyl ligands, except complex 8, which exhibits comparable or better inhibition activity than those of the mixed-ligand oxovanadium(IV) complexes of SAA derivative with polypyridyl ligands. The results demonstrate that the structures of vanadium complexes influence the PTP1B inhibition activity. Kinetics assays reveal that complex 2 inhibits PTP1B in a competitive manner.  相似文献   

18.
This work reports an efficient Lewis acid catalysed N‐methylation procedure of lipophilic α‐amino acid methyl esters in solution phase. The developed methodology involves the use of the reagent system AlCl3/diazomethane as methylating agent and α‐amino acid methyl esters protected on the amino function with the (9H‐fluoren‐9‐yl)methanesulfonyl (Fms) group. The removal of Fms protecting group is achieved under the same conditions to those used for Fmoc removal. Thus the Fms group can be interchangeable with the Fmoc group in the synthesis of N‐methylated peptides using standard Fmoc‐based strategies. Finally, the absence of racemization during the methylation reaction and the removal of Fms group were demonstrated by synthesising a pair of diastereomeric dipeptides. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

19.
In acetonitrile, reactions of bis(acetylacetonato)oxidovanadium(IV) ([VO(acac)2]) with 4-R-benzoylhydrazine in 1:1 mole ratio provide coordinatively symmetrical complexes (1-5) of the {OV(μ-O)VO}4+ motif in 40-47% yields. On the other hand, in methanol the same reactants provide complexes (6-10) containing the {OV(μ-OMe)2VO}4+ core in 37-50% yields. In both series of complexes, the ligand is the O,N,O-donor deprotonated Schiff base system 4-R-benzoic acid (1-methyl-3-oxo-butylidene)-hydrazide formed by template condensation of acac with 4-R-benzoylhydrazine (R = H, Cl, OMe, NO2 and NMe2). All the complexes have been characterized by elemental analysis, magnetic and spectroscopic (IR, UV-Vis and NMR) measurements. Molecular structures of three representative complexes (4, 6 and 7) have been determined by X-ray crystallography. In each complex, the dianionic planar ligand is coordinated to the metal centre via the enolate-O, the imine-N and the O-atom of the deprotonated amide functionality. Cyclic voltammetric measurements in dichloromethane revealed that complexes 1-5 are redox inactive, while complexes 6-10 display a metal centred reduction in the potential range −0.06 to 0.0.32 V (versus Ag/AgCl).  相似文献   

20.
Glycosynthase mutants obtained from Thermotogamaritima were able to catalyze the regioselective synthesis of aryl β-d-Galp-(1→3)-β-d-Glcp and aryl β-d-Glcp-(1→3)-β-d-Glcp in high yields (up to 90 %) using aryl β-d-glucosides as acceptors. The need for an aglyconic aryl group was rationalized by molecular modeling calculations, which have emphasized a high stabilizing interaction of this group by stacking with W312 of the enzyme. Unfortunately, the deprotection of the aromatic group of the disaccharides was not possible without partial hydrolysis of the glycosidic bond. The replacement of aryl groups by benzyl ones could offer the opportunity to deprotect the anomeric position under very mild conditions. Assuming that benzyl acceptors could preserve the stabilizing stacking, benzyl β-d-glucoside firstly assayed as acceptor resulted in both poor yields and poor regioselectivity. Thus, we decided to undertake molecular modeling calculations in order to design which suitable substituted benzyl acceptors could be used. This study resulted in the choice of 2-biphenylmethyl β-d-glucopyranoside. This choice was validated experimentally, since the corresponding β-(1→3) disaccharide was obtained in good yields and with a high regioselectivity. At the same time, we have shown that phenyl 1-thio-β-d-glucopyranoside was also an excellent substrate leading to similar results as those obtained with the O-phenyl analogue. The NBS deprotection of the S-phenyl group afforded the corresponding disaccharide quantitatively.  相似文献   

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