摘要:

The molecular rotational symmetry number, [sgrave], is defined and evaluated for a wide range of rigid organic compounds. Molecular symmetry is an important determinant of a variety of properties of crystalline substances. It is shown that the entropy of melting, ΔSm, is related to symmetry by ΔSm= 13.5–RIn[sgrave]. Since molecular symmetry plays an important role in the determination of the entropy of melting it is also important in determining vapor pressure and ideal solubility, both of which depend upon entropy of melting.

ISSN:1062-936X    

DOI:10.1080/10629369308029892

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Simple techniques to predict the melting point (Tm) and boiling point (Tb) of non-hydrogen bonding rigid molecules have been developed. The compounds used include halogen, methyl, cyano, and nitro derivatives of benzene and polycyclic compounds. Melting point prediction uses additive constitutive properties e.g., molecular fragments and a non-additive non-constitutive property, molecular symmetry. Boiling point estimation employs only additive constitutive properties. It was found that symmetry affects the entropy of melting which in turn affects the melting point.

ISSN:1062-936X    

DOI:10.1080/10629369308029893

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The activity of a set of anilide inhibitors of the Hill reaction was modeled using the traditional Hansch approach and Comparative Molecular Field Analysis (CoMFA). In the “best” Hansch model the most relevant parameters were the hydrophobic constants associated to substituents at the 3- and 4-positions of the benzene ring (π3and π4) and theB1Verloop's parameter describing the “minimum width” of the substituent attached to the carbonyl. Successively, a combined “Hansch–CoMFA” analysis was performed using as descriptors the steric field of the acyl substituents in conjunction with the π3and π4constants multiplied by proper weighting factors. The results of this latter type of analysis were significantly better than those obtained through the traditional Hansch approach. The predictive ability of the “Hansch–CoMFA” model was further tested by predicting the activity of a large number of anilides not included in the training set. The residuals of such predictions indicated that the Hansch–CoMFA model was characterized by higher predictive ability and confirmed the efficiency of such a 3D–QSAR method in handling shape-dependent factors.

ISSN:1062-936X    

DOI:10.1080/10629369308029894

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The toxicity of chemicals is orthogonal with individual molecular descriptors used to quantify hydrophobicity and soft electrophilicity when considering large data sets. Estimating the toxicity of reactive chemicals requires descriptors of both passive transport and the stereoelectronic interaction, which are largely independent processes. QSARs using either logPor an electronic parameter alone are only significant for sets of chemicals that represent special, albeit some important, cases in QSAR.

ISSN:1062-936X    

DOI:10.1080/10629369308029895

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Using the molecular modeling program SYBYL, a conformational analysis of epibatidine has been performed. Two pairs of stable conformations due to the rotational degree of freedom for the pyridine ring have been found. These conformations were compared with morphine regarding spatial arrangements as well as electronic aspects. A very close agreement between the essential receptor positions occurring in morphine and epibatidine could be demonstrated. The protonable nitrogen atom in epibatidine is in exactly the same spatial position as in morphine, if the pyridine ring and the phenolic ring of morphine were matched to each other. Interestingly, it is also apparent that the pyridine nitrogen atom is in a close position to the bridging oxygen atom of morphine. Furthermore, the chlorine substituent fits very well with the hydroxyl group of morphine. A chemical reaction is postulated to permit epibatidine to function as an analgesic. The carbon-chlorine bond should be activated by the neighbourhood of the nitrogen atom in the pyridine ring and therefore undergo a chemical reaction resulting in formation of a covalent bond, perhaps of an oxygen bridge between the opioid receptor and epibatidine.

ISSN:1062-936X    

DOI:10.1080/10629369308029896

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Colombo, A.G. (1992).Environmental Impact Assessment. Kluwer Academic Publishers, Dordrecht, p. 334 + xii pp., Hardcover, ISBN: 0-7923-1589-8, Dfl180.00; £61.00.

ISSN:1062-936X    

DOI:10.1080/10629369308029897

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:1062-936X    

DOI:10.1080/10629369308029898

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:1062-936X    

DOI:10.1080/10629369308029891

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor