749 publications from this institution
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnitude and origin of the .beta.-silicon effect on carbenium ionsScott G. Wierschke, Jayaraman Chandrasekhar, and William L. JorgensenCite this: J. Am. Chem. Soc. 1985, 107, 6, 1496–1500Publication Date (Print):March 1, 1985Publication History Published online1 May 2002Published inissue 1 March 1985https://pubs.acs.org/doi/10.1021/ja00292a008https://doi.org/10.1021/ja00292a008research-articleACS PublicationsRequest reuse permissionsArticle Views2076Altmetric-Citations254LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts
The decarboxylation of imidazolidin-2-one-1-carboxylate anion 2 has been investigated via combined quantum and statistical mechanics methodology. Monte Carlo statistical mechanics simulations utilizing free-energy perturbation theory and PDDG/PM3 for the QM method yielded free-energy profiles for the reaction in water, methanol, acetonitrile, and mixed solvents. The results for free energies of activation are uniformly in close accord with experimental data and reflect large rate accelerations in progressing from protic to dipolar aprotic media. Structural and energetic analyses confirm that the rate retardation in protic solvents comes from loss of hydrogen bonding in progressing from the carboxylate anion 2 to the more charge-delocalized transition state (TS). The structure of the TS is found to be significantly affected by the reaction medium; it occurs at a 0.2-Å shorter C−N separation in protic solvents than in acetonitrile. Characterization of the hydrogen bonding for 2 and the TS also provided insights for design of decarboxylase catalysts, namely, it is desirable to have three hydrogen-bond donating groups positioned to interact with the ureido oxygen along with two hydrogen-bond donors positioned to interact with the ureido nitrogen of the breaking C−N bond.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSN2 reaction profiles in the gas phase and aqueous solutionJayaraman Chandrasekhar, Scott F. Smith, and William L. JorgensenCite this: J. Am. Chem. Soc. 1984, 106, 10, 3049–3050Publication Date (Print):May 1, 1984Publication History Published online1 May 2002Published inissue 1 May 1984https://pubs.acs.org/doi/10.1021/ja00322a059https://doi.org/10.1021/ja00322a059research-articleACS PublicationsRequest reuse permissionsArticle Views1321Altmetric-Citations242LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVEditorialNEXTA Reflection on Norman Louis AllingerHenry F. Schaefer IIIHenry F. Schaefer, IIICenter for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602-2525, United StatesMore by Henry F. Schaefer, IIIhttp://orcid.org/0000-0003-0252-2083 and William L. Jorgensen*William L. JorgensenDepartment of Chemistry, Yale University, New Haven, Connecticut 06417, United States*Email: [email protected]More by William L. Jorgensenhttp://orcid.org/0000-0002-3993-9520Cite this: J. Chem. Theory Comput. 2021, 17, 4, 2013Publication Date (Web):March 17, 2021Publication History Published online17 March 2021Published inissue 13 April 2021https://pubs.acs.org/doi/10.1021/acs.jctc.1c00252https://doi.org/10.1021/acs.jctc.1c00252editorialACS PublicationsCopyright © Published 2021 by American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views1350Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (454 KB) Get e-AlertscloseSUBJECTS:Chemical calculations,Computational chemistry,Molecular mechanics,Organic compounds,QM/MM Get e-Alerts
The effect of reintroducing the overlap matrix into the secular equations for an NDDO (neglect of diatomic differential overlap)-based semiempirical molecular orbital method has been investigated. The modification is expected to improve the description of interactions between electron pairs. The idea has been tested by implementation and evaluation of a nonorthogonal version of the MNDO method (NO-MNDO) with parametrization for hydrogen, carbon, nitrogen, and oxygen. Overall, the accuracy of NO-MNDO for heats of formation is nearly identical to that for the more highly parametrized AM1 method. The mean absolute error (MAE) for heats of formation of a comprehensive set of 622 neutral, closed-shell molecules is reduced from 8.4 kcal/mol with MNDO to 6.8 kcal/mol with NO-MNDO. In addition, the performance for conformational equilibria and torsional barriers is significantly improved with NO-MNDO, presumably owing to the improved description of closed-shell interactions. For molecular geometries, the usual training and test sets have been expanded through use of MP2/6-31G(d) results for consistent comparisons. The performance of NO-MNDO for bond lengths, bond angles, and dihedral angles remains good with MAEs of 0.017 Å, 2.5°, and 4.5°. Additionally, NO-MNDO corrects severe errors by MNDO for R(•) + H-R' hydrogen-atom transfers, while testing for activation barriers for nine pericyclic reactions reveals only modest improvement.
No abstract is provided for this article.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOptimized intermolecular potential functions for liquid alcoholsWilliam L. JorgensenCite this: J. Phys. Chem. 1986, 90, 7, 1276–1284Publication Date (Print):March 1, 1986Publication History Published online1 May 2002Published inissue 1 March 1986https://pubs.acs.org/doi/10.1021/j100398a015https://doi.org/10.1021/j100398a015research-articleACS PublicationsRequest reuse permissionsArticle Views3757Altmetric-Citations1033LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdditions and Corrections - Chemical Consequences of Orbital Interactions. II. Ethylene and Butadiene Bridged Polycyclic Hydrocarbons Containing Three- and Four-Membered Rings.William JorgensenCite this: J. Am. Chem. Soc. 1975, 97, 22, 6607Publication Date (Print):October 1, 1975Publication History Published online4 February 2004Published inissue 1 October 1975https://pubs.acs.org/doi/10.1021/ja00855a606https://doi.org/10.1021/ja00855a606research-articleACS PublicationsRequest reuse permissionsArticle Views24Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTImportance of secondary interactions in triply hydrogen bonded complexes: guanine-cytosine vs uracil-2,6-diaminopyridineWilliam L. Jorgensen and Julianto PranataCite this: J. Am. Chem. Soc. 1990, 112, 5, 2008–2010Publication Date (Print):February 1, 1990Publication History Published online1 May 2002Published inissue 1 February 1990https://pubs.acs.org/doi/10.1021/ja00161a061https://doi.org/10.1021/ja00161a061research-articleACS PublicationsRequest reuse permissionsArticle Views3337Altmetric-Citations475LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComputer-assisted mechanistic evaluation of organic reactions. 11. Electrophilic aromatic substitutionMark G. Bures, Barbara L. Roos-Kozel, and William L. JorgensenCite this: J. Org. Chem. 1985, 50, 23, 4490–4498Publication Date (Print):November 1, 1985Publication History Published online1 May 2002Published inissue 1 November 1985https://pubs.acs.org/doi/10.1021/jo00223a015https://doi.org/10.1021/jo00223a015research-articleACS PublicationsRequest reuse permissionsArticle Views394Altmetric-Citations12LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
A joint QM/MM and ab initio study on the decomposition of urea in the gas phase and in aqueous solution is reported. Numerous possible mechanisms of intramolecular decomposition and hydrolysis have been explored; intramolecular NH3 elimination assisted by a water molecule is found to have the lowest activation energy. The solvent effects were elucidated using the TIP4P explicit water model with free energy perturbation calculations in conjunction with QM/MM Monte Carlo simulations. The explicit representation of the solvent was found to be essential for detailed resolution of the mechanism, identification of the rate-determining step, and evaluation of the barrier. The assisting water molecule acts as a hydrogen shuttle for the first step of the elimination reaction. The forming zwitterionic intermediate, H3NCONH, participates in 8−9 hydrogen bonds with water molecules. Its decomposition is found to be the rate-limiting step, and the overall free energy of activation for the decomposition of urea in water is computed to be ∼37 kcal/mol; the barrier for hydrolysis by an addition/elimination mechanism is found to be ∼40 kcal/mol. The differences in the electronic structure of the transition states of the NH3 elimination and hydrolysis were examined via natural bond order analysis. Destruction of urea's resonance stabilization during hydrolysis via an addition/elimination mechanism and its preservation in the rearrangement to the H3NCONH intermediate were identified as important factors in determining the preferred reaction route.
No abstract is provided for this article.
