{"title":"A quantum mechanical force field for amidocyano-pyridinium methylide. Force field transferability to the cycloimmonium ylides","authors":"Y. Karzazi, G. Vergoten, G. Surpateanu","doi":"10.1002/ejtc.39","DOIUrl":"10.1002/ejtc.39","url":null,"abstract":"","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"2 1","pages":"85-95"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ejtc.39","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74008413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Molecules‐3D version 2.10D for Windows","authors":"A. Hinchliffe","doi":"10.1002/EJTC.13","DOIUrl":"https://doi.org/10.1002/EJTC.13","url":null,"abstract":"","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"21 1","pages":"81-82"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81589209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Theoretical study of the stable C2 and Cs symmetry isomers of urea","authors":"M. Spoliti, A. Pieretti, L. Bencivenni, N. Sanna","doi":"10.1002/ejtc.49","DOIUrl":"10.1002/ejtc.49","url":null,"abstract":"","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"2 1","pages":"149-159"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ejtc.49","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88065036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
SUMMARY It is shown that heteroatomic analogs of benzocyclopropene involving NH, O and S groups at position 7 exhibit enhanced selectivity in the electrophilic substitution r eactions. The origin of the different susceptibility of the -a nd-positions toward electrophilic attack is interpreted by the compatibility and incompatibility of two -electron localization modes. The first is induced by the angular strain of the small fused ring and its lone pair(s) electrons thus being a property of the ground state (GS). The second is caused by protonation of the benzene fragment occurring in the formation of the transition structure (TS). The competition between these two antagonistic localization patterns is responsible for enhanced activity of -sites over the -positions, which is in harmony with the original Mills‐Nixon (MN) hypothesis. The actual values of the corresponding proton affinities are affected also by Coulomb interactions between the carbon junction atom(s) and heteroatomic group within the three-membered ring. On the other hand, 7,7- difluorobenzocyclopropene exhibits a reversed behavior: the -site is preferred over the - position, which is in accordance with the predicted anti-MN character of this compound. Chemical relevance of the MN effect is stressed.
{"title":"Further evidence for existence of the Mills-Nixon effect— ab initio study of the electrophilic reactivity in heteroanalogs of benzocyclopropene","authors":"Z. Maksić, D. Kovaček, B. Kovačević","doi":"10.1002/EJTC.11","DOIUrl":"https://doi.org/10.1002/EJTC.11","url":null,"abstract":"SUMMARY It is shown that heteroatomic analogs of benzocyclopropene involving NH, O and S groups at position 7 exhibit enhanced selectivity in the electrophilic substitution r eactions. The origin of the different susceptibility of the -a nd-positions toward electrophilic attack is interpreted by the compatibility and incompatibility of two -electron localization modes. The first is induced by the angular strain of the small fused ring and its lone pair(s) electrons thus being a property of the ground state (GS). The second is caused by protonation of the benzene fragment occurring in the formation of the transition structure (TS). The competition between these two antagonistic localization patterns is responsible for enhanced activity of -sites over the -positions, which is in harmony with the original Mills‐Nixon (MN) hypothesis. The actual values of the corresponding proton affinities are affected also by Coulomb interactions between the carbon junction atom(s) and heteroatomic group within the three-membered ring. On the other hand, 7,7- difluorobenzocyclopropene exhibits a reversed behavior: the -site is preferred over the - position, which is in accordance with the predicted anti-MN character of this compound. Chemical relevance of the MN effect is stressed.","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"70 1","pages":"65-78"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86282922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Chavatte, P. Lagant, J. P. Henichart, D. Lesieur, G. Vergoten
{"title":"Conformational investigations of two diastereoisomers of the tripeptide Nα-Z-Nϵ-Bz-Lys-Ala-Sar-OBzl. 1. Molecular dynamics simulations using the AMBER and the SPASIBA force fields","authors":"P. Chavatte, P. Lagant, J. P. Henichart, D. Lesieur, G. Vergoten","doi":"10.1002/ejtc.46","DOIUrl":"10.1002/ejtc.46","url":null,"abstract":"","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"2 1","pages":"195-205"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ejtc.46","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81616092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ab initio study of 3‐furyl fulgide II. Substituent effects on photochemical reactions","authors":"Y. Yoshioka, M. Irie","doi":"10.1002/EJTC.24","DOIUrl":"https://doi.org/10.1002/EJTC.24","url":null,"abstract":"","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"125 1","pages":"191-198"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77232057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Elass, G. Vergoten, P. Dhamelincourt, R. Becquet
{"title":"A scaled quantum mechanical force field for hexachlorocyclophosphazene trimer (NPCl2)3. Force field transferability to the octachlorocyclophosphazene tetramer (NPCl2)4 and the decachlorocyclophosphazene pentamer (NPCl2)5","authors":"A. Elass, G. Vergoten, P. Dhamelincourt, R. Becquet","doi":"10.1002/ejtc.32","DOIUrl":"10.1002/ejtc.32","url":null,"abstract":"","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"2 1","pages":"11-23"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ejtc.32","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83700860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gibbs paradox statement of entropy of mixing has been regarded as the theoretical foundation of statistical mechanics, quantum theory and biophysics. A large number of relevant chemical and physical observations show that the Gibbs paradox statement is false. We also disprove the Gibbs paradox statement through consideration of symmetry, similarity, entropy additivity and the defined property of ideal gas. A theory with its basic principles opposing Gibbs paradox statement emerges: entropy of mixing increases continuously with the increase in similarity of the relevant properties. Many outstanding problems, such as the validity of Pauling’s resonance theory and the biophysical problem of protein folding and the related hydrophobic effect, etc. can be considered on a new theoretical basis. A new energy transduction mechanism, the deformation, is also briefly discussed.
{"title":"Gibbs paradox of entropy of mixing: experimental facts, its rejection and the theoretical consequences","authors":"Shu-Kun Lin","doi":"10.1002/EJTC.27","DOIUrl":"https://doi.org/10.1002/EJTC.27","url":null,"abstract":"Gibbs paradox statement of entropy of mixing has been regarded as the theoretical foundation of statistical mechanics, quantum theory and biophysics. A large number of relevant chemical and physical observations show that the Gibbs paradox statement is false. We also disprove the Gibbs paradox statement through consideration of symmetry, similarity, entropy additivity and the defined property of ideal gas. A theory with its basic principles opposing Gibbs paradox statement emerges: entropy of mixing increases continuously with the increase in similarity of the relevant properties. Many outstanding problems, such as the validity of Pauling’s resonance theory and the biophysical problem of protein folding and the related hydrophobic effect, etc. can be considered on a new theoretical basis. A new energy transduction mechanism, the deformation, is also briefly discussed.","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"14 1","pages":"135-151"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73171672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rate of intercage diffusion (k c ) along with rate of cage visits (k v ) and diffusion coefficient (D) of sorbates in zeolite Y have been calculated. We show that as a consequence of the dependence of rate of intercage diffusion on short-time behaviour, significant deviation from the Arrhenius behaviour at suffciently high temperatures occurs.
{"title":"Deviation from Arrhenius behaviour of rate of intercage diffusion in Zeolite Y1","authors":"P. Santikary, S. Yashonath","doi":"10.1002/EJTC.15","DOIUrl":"https://doi.org/10.1002/EJTC.15","url":null,"abstract":"Rate of intercage diffusion (k c ) along with rate of cage visits (k v ) and diffusion coefficient (D) of sorbates in zeolite Y have been calculated. We show that as a consequence of the dependence of rate of intercage diffusion on short-time behaviour, significant deviation from the Arrhenius behaviour at suffciently high temperatures occurs.","PeriodicalId":100404,"journal":{"name":"Electronic Journal of Theoretical Chemistry","volume":"62 1","pages":"87-92"},"PeriodicalIF":0.0,"publicationDate":"2001-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79094101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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