摘要:

AbstractBis(2,2′‐bipyridine)dioxovanadium(V) trifluoromethanesulfonate, obtained from autooxidation of the corresponding oxovanadium(IV) complex, crystallizes in monoclinic,P21/n, witha= 15.433(2),b= 11.013(2),c= 27.423(2) Å, β = 104.79(2)°,Z= 4,R= 0.0697, andRw= 0.0821. The complex consists of discrete vanadium(V) complex cations and trifluoromethanesulfonate anions. Each asymmetric unit is composed of a pair of enantiomer molecules. The octahedral vanadium complex ion, having aC2axis, comprises acis‐VO2, mean V‐O distance of 1.622 ± 0.007 Å, and twocis‐related 2,2′‐bipyridine ligands. The V‐N bondstransto each other are short, with a mean V‐N distance of 2.108 ± 0.010 Å, while thosetransto V=O are somewhat longer, with a mean V‐N distance of 2.292 ± 0.022 Å. The coordination geometry of the vanadium cation is very similar to that of

ISSN:0009-4536    

DOI:10.1002/jccs.199800011

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractThe reactions of R1R2CpM(CO)3−Li+(M = Mo, W) with α, α′‐dichloro‐p‐xylene yieldedp‐xylyl bridged dinuclear complexes of R1R2CpM(CO)3in high yields. All of such new complexes are very stable to air and water. Some of them are stable even in dilute acids and dilute bases. Complex 4 crystallizes in the monoclinic system, space groupP21/n, with a = 6.847(5) Å, b = 9.838(2) Å, c = 25.140(10) Å, β = 96.56(5)°, Z = 2, RF=0.077, Rw= 0.105 and

ISSN:0009-4536    

DOI:10.1002/jccs.199800012

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractThe 3‐methylsydnone (CH3Sd) and 3‐phenylsydnone (PhSd) complexes of pentacyanoferrate(II) were prepared in aqueous solution by the reaction of Fe(CN)5OH23−with excess ligand. Metal to ligand charge transfer transitions were observed for both complexes at 442 nm (CH3Sd) and 494 nm (PhSd), respectively. The reduction potentials were measured with the Efvalues of 0.65 and 0.67 V (vs. NHE) for CH3Sd and PhSd, respectively, at 25 °C, μ = 0.10 M LiClO4and pH = 5. The kinetics of the substitution reaction were also investigated, and kfand kdvalues (25 °C, μ = 0.10 M LiClO4,pH = 5) are (5.4 ± 0.2) × 10−2M−1s−1and (1.4 + 0.1) × 10−5s−1(CH3Sd), (8.8 ±0.1) × 10−2M−1s−1and (4.7 ±0.1) × 10−5s−1(PhSd). The kfvalues for both sydnone complexes are approximately four orders of magnitude smaller than other pentacyanoferrate(II) complexes with neutral ligands. The difference may arise from the mesoionic character of the sydnone compounds rather than via a different reaction mechanism. Spectroscopic, kinetic and electrochemical results all suggest that the sydnone ring shows a better π‐backbonding stabilization with Fe(CN)5

ISSN:0009-4536    

DOI:10.1002/jccs.199800013

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractA new dicopper(I) complex of 4‐methyl‐2,6‐bis(pyrazol‐1‐ylmethyl)phenolate (LOH) has been synthesized by the reaction ofLOHwith Cul to formLOHCu2I2(1), which catalyzes the oxidation of 3,5‐di(t‐butyl)catechol.LOHCu2I2reacts with molecular oxygen to form a peroxo‐dicopper(II) complex and undergoes cleavage of 0–0 bridge to give a new μ4‐oxo‐Cu11tetramer withseven‐memberedring coordination as characterized

ISSN:0009-4536    

DOI:10.1002/jccs.199800014

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractCitrusbacterial canker caused byXanthomomas campestrispv.citri(Hasse 1915) Dye 1978, a gram‐negative and rod‐shape bacteria, is one of the destructive diseases ofCitrus.There is marked diversity in resistance to the disease amongCitrusplants. Calamondin,Citrus madurensisLour. (Shiki‐kitsu) is one of the highly resistant plants.1In resistant plants bacterial multiplication is restrained by the embedding of electron dense materials in intercellular spaces.2This suggests the presence of an antibacterial substance in resistant plants.The third author assayed the 85% ethanol extracts ofCitrusleaves infected with bacterial canker for static activities toX. campestris.pv.citri.An active fraction was found in Calamondin. We further purified and characterized its ingredients on the basis of spectrometric analyses. Its structure was found to be identical with 3‐hydroxy‐5,6,7,8,3′,4′‐hexamethoxyflavone (1) isolated fromCitrus natsudaidaiHayata. However, its antibacterial activity is first

ISSN:0009-4536    

DOI:10.1002/jccs.199800015

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractTwo new sodium salts of aristolochic acids: sodium aristolochate‐II and ‐IVa, together with ten known compounds: sodium aristolochate‐I, sodium aristolochate‐C, aristolactam, aristolactam‐N‐β‐D‐glucoside, cepharadione‐A, 3,5‐pyridinedicarboxamide,p‐hydroxybenzaldehyde,trans‐methylp‐coumarate, 6‐hydroxy sitost‐4‐en‐3‐one, β‐sitosterone and β‐sitosterol, and stigmasterol mixture were isolated from the fresh flowers and fruits ofAristolochia zollingeriatia.Their structures were deterimined by spectral and chemical methods. IR and1H NMR methods to distinguish ari

ISSN:0009-4536    

DOI:10.1002/jccs.199800016

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractTwo new peroxyterpenyl coumarins including peroxyschininallylol [7‐(3′, 7′‐dimethyl‐6′‐hydroperoxyocta‐2′, 7′‐dienyloxy)‐8‐methoxy coumarin] and peroxyschinilenol [7‐(3′, 7′‐dimethyl‐7′‐hydroperoxyocta‐2′, 7′‐dienyloxy‐8‐methoxy coumarin]were isolated from the chloroform‐soluble part of the root bark ofZanthoxylum schinifolium.The structures of

ISSN:0009-4536    

DOI:10.1002/jccs.199800017

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractTwenty‐four compounds including three flavonoids, kaempferol‐3‐O‐rhamnoside (1), quercetin‐3‐O‐rhamnoside (2), and taxifolin‐3‐O‐rhamnoside (3); three ferulates, docosanylferulate (4), tetracosanylferulate (5), and hexacosanylferulate (6); two cyclohex‐2‐en‐1‐ones, blumenol A (7), and roseoside (8); two sesquiterpenes, zeylanidine (9), and zeylanicine (10); four triterpenes, lupeol (11), lupenone (12), taraxerol (13), and taraxerone (14); one steroid, β‐sitosterol (15); one amide,N‐trans‐feruloylmethoxytyramine (16); eight alkaloids, roemerine (17), actinodaphnine (18),N‐methylactinodaphnine (19), glaucine (20), and oxoglaucine (21), boldine (22), corydine (23) and methoxyannomontine (24) were isolated fromNeolitsea parvigemmaandN. konishii.These compounds were characterized and identified by physical and spectral evidence. Among them, compounds1, 2, 3, 4, 5, 6, 7, 8, 13, 14, 16, 20, 21, 23, and24, were isolated for the first time from this genus. This finding is

ISSN:0009-4536    

DOI:10.1002/jccs.199800018

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractThree new naphthoquinone derivatives, isolated from the stems ofDiospyros maritimaBlume, were elucidated as 2′‐ethoxyisodiospyrin, 3′‐ethoxyisodiospyrin, and 3‐ethoxyisodiospyrin, respectively, on the basis of spectral p

ISSN:0009-4536    

DOI:10.1002/jccs.199800019

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractThe intensity changes of proton NMR resonances of NADPH and NADP+were employed to monitor the oxidation of NADPH in the presence of dihydrofolate reductase (DHFR) fromEscherichia coli.It was found that in addition to the normal reductase activityE. colidihydrofolate reductase (DHFR) also catalyzes oxygen‐dependent oxidation of NADPH to NADP+in the absence of folate or dihydrofolate. Mutant‐type DHFR (Asp27→Asn) shows almost no activity at pH 7.0, while at pH 4.0 it regains its activity. This enzymatic activity is characterized by a fast initial rate followed by a gradual leveling‐off (slow phase), which appears to be due to the depletion of oxygen in the solution, under our experimental conditions. From the NADP concentration at the fast phase we estimated that four moles of NADPH were oxidized per mole of oxygen consumed. The specific activity, determined from the initial rate of NADPH oxidation, is highly pH dependent. It decreases from 9.6 × 10−3units/mg protein at pD = 5.2 to 0.56 × 103units/mg at pD = 8.0 at 21 °C. The pH dependence fits quite well to a titration curve of a single group with pKa = 6.5. DHFR inhibitors, trimethoprim (TMP) and methotrexate (MTX) completely inhibit this activity, whereas folate and H4F do not. NADP+appears to partially inhibit this reaction. Thus this oxidative activity of DHFR shares several similar characteristics of the normal reductase activity and suggests some common structural

ISSN:0009-4536    

DOI:10.1002/jccs.199800020

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY