摘要:

AbstractThe results of low temperature X‐ray determination, Mössbauer and magnetic measurement of spin‐crossover (isothiocyanato)(porphinato)iron(III) hemipyridine are reported. The features in 77 K Mössbauer spectrum include two doublets, one with a quadrupole splitting (ΔEQ) of 1.961 mm s−1(low‐spin site) and the other with ΔEQ= 0.792 mm s−1(high‐spin site). As the temperature of the sample is increased to 300 K, the signal intensity of the high‐spin site grows to 92% at the expense of the low‐spin signal. The variable‐temperature magnetic susceptibility data also support that the tetraphenyl complex is a s

ISSN:0009-4536    

DOI:10.1002/jccs.199900001

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

AbstractThis article reviews some of the fundamental scientific issues associated with solid inclusion compounds, and describes the approaches and strategies that may be used to investigate the structural, dynamic and chemical properties of these systems. Two particular families of solid organic inclusion compounds ‐ the urea and thiourea inclusion compounds ‐ are highlighted. In order to understand the fundamental nature of these solids, it has been necessary to apply a wide range of experimental, computational and theoretical approaches. Each technique provides information on a different aspect of the solid, and the combined information obtained from these complementary approaches allows a comprehensive understanding to be established. Several issues of contemporary interest for urea and thiourea inclusion compounds are described, and the approaches that have been taken towards a fundamental understanding of these systems are explai

ISSN:0009-4536    

DOI:10.1002/jccs.199900002

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

AbstractThe determination of crystal structures from single crystal diffraction data can generally be carried out routinely and straightforwardly. However, many crystalline solids can be obtained only as microcrystalline powders and are not suitable for investigation by conventional single crystal diffraction methods. In the past, this problem has limited the ability to elucidate the structural properties of such materials. For the wide range of materials in this category, there is clearly a pressing need to develop and exploit techniques that allow crystal structures to be solved from powder diffraction data. Although traditional techniques for structure solution from powder diffraction data have been applied successfully in several cases, these techniques have certain intrinsic limitations, and for the case of organic molecular crystals the challenges that must be overcome are particularly severe. For these reasons, our recent research has focused on the development and implementation of new methodologies for structure solution from powder diffraction data, leading to new “direct‐space” techniques for structure solution in which a hypersurface based on the profile R‐factor is searched using Monte Carlo or Genetic Algorithm techniques. This paper presents a brief overview of the problems and challenges associated with structure solution from powder diffraction data. The foundations of the techniques that we have developed are described, and illustrative examples (from the field of organic molecular crystals) are given to highlight the application of these tec

ISSN:0009-4536    

DOI:10.1002/jccs.199900003

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

Abstract1,2,3‐Trisubstituted azulene analogs6aand6beasily underwent methoxylation in position4or6of an azulene ringvia anelectrochemical oxidation. It is a simple, convenient and selective method for introducing a methoxy group into a 7‐membered ring of azulene analogs when compared with traditional chemical methods. It could be useful in preparing 2,4‐ and 2,6‐azuloquinone

ISSN:0009-4536    

DOI:10.1002/jccs.199900004

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

AbstractA formal synthesis of (±)‐mitsugashiwalactone (1) and (±)‐isodihydro nepetalactone (2) was accomplished. Baeyer‐Villiger lactonization of ketone9followed by acidic treatment led to the rearranged lactone8, which underwent a series of functional group transformations to give cyclopentanone derivatives19and20. Shapiro reaction on21and22in the presence of excess dry ice gave lactones5and6. Lactones5and6previously have been converted to mitsugashiwalactone (1) and isodihydronepetalactone (2), respe

ISSN:0009-4536    

DOI:10.1002/jccs.199900005

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

AbstractThree strains ofGanoderma tsugae (CCRC36065, CCRC37034, CCRC37038)and three strains ofGanoderma lucidum (CCRC36021, CCRC37029, CCRC37033)were cultivated. Their triterpenoid patterns of the fruit body were analyzed by reverse phase HPLC using a gradient elution of acetonitrile/2% acetic acid (1/4 and 1/2). The triterpenoid patterns ofG. tsugaeandG. lucidumare different. But similar 2 and 3 dimensional patterns are obtained among three strains ofG. tsugae.Different patterns are found among different strains ofG. lucidum.Ganoderic acid A(1), B(2), C(3) and D(4) were isolated from the ethanol extract ofG. tsugae.

ISSN:0009-4536    

DOI:10.1002/jccs.199900006

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

AbstractA series of biphenylyltetrazole substituted triazinones and structure‐related pyrimidinones are systhesized, and their binding affinities for angiotensin II receptor are reporte

ISSN:0009-4536    

DOI:10.1002/jccs.199900007

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

AbstractThe phenyl ring of 3‐(4‐hydrazinocarbonylphenyl)sydnone activates a hydrazinocarbonyl group to undergo a series of reactions for preparing heterocyclic compounds including oxadiazoles, dihydropyrroles, and pyrroles. However, the hydrazinocarbonyl group on theC(4)‐CH2resists a cyclization under the same reaction condi

ISSN:0009-4536    

DOI:10.1002/jccs.199900008

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

Abstract6‐Aminouracil and 6‐aminothiouracil (1a, b) were reacted with benzylidenemalononitrile2ato afford the pyrido[2,3‐d]pyrimidines4a, b. On the other hand, the reaction of1a, bwith benzylidene ethyl cyanoacetate2bresult in a mixture of5a,band/or6a,brespectively. Pyrido[2,3‐d]thiazolo[1,2‐b]pyrimidines8a‐cwere synthesized from the reaction of4bwith α‐halo compounds to give the intermediate derivatives7a‐cfollowed by cyclization

ISSN:0009-4536    

DOI:10.1002/jccs.199900009

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY

摘要:

AbstractA newN‐fatty acyl tryptamine, cheritamine (30), along with thirty‐two compounds including nineteen benzenoids,p‐hydroxybenzadehyde (1),p‐hydroxybenzoic acid (2), methylparabene (3), 3‐chlorobenzoic acid (4), vanillin (5), isovanillin (6), vanillic acid (7), isovanillic acid (8), methyl vanillate (9), methyl isovanillate (10), syringaldehyde (11), syringic acid (12), 3,4,5‐trimethoxybenzoic acid (13),trans‐methylp‐coumarate (14), ferulic acid (15),p‐dihydrocoumaric acid (16), 3‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐1,2‐propanediol (17),3,4,5‐trimethoxyphenyl‐β‐D‐glucopyranoside (18) and thalictoside (19); onep‐quinone, 2,6‐dimethoxy‐p‐quinone (20); one purine, uridine (21); eight alkaloids, nicotinic acid (22), thalifoline (23), doryphornine (24), (–)‐norstephalagine (25), (‐)‐romucosine (26), (+)‐pronuciferine (27), (+)‐norisocorydine (28) and oxoasimilobine (29) and three steroids, β‐sitosterol‐D‐glucoside (31), stigmasterol‐D‐glucoside (32) and 6′‐(β‐sitosteryl‐3‐O‐β‐glucopyranosidyl)hexadecanoate (33), are isolated from the stems ofAnnona cherimol

ISSN:0009-4536    

DOI:10.1002/jccs.199900010

出版商:WILEY‐VCH Verlag    

年代:1999

数据来源: WILEY