From owner-chemistry@ccl.net Fri Aug 3 16:16:01 2007 From: "Ivanciuc, Ovidiu I. oiivanci!A!utmb.edu" To: CCL Subject: CCL: Quantifying/estimating donor/acceptor strength Message-Id: <-34872-070803160932-22814-EYqXH5q29MT+r7VVkf+EGQ::server.ccl.net> X-Original-From: "Ivanciuc, Ovidiu I." Content-class: urn:content-classes:message Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="iso-8859-1" Date: Fri, 3 Aug 2007 15:09:11 -0500 MIME-Version: 1.0 Sent to CCL by: "Ivanciuc, Ovidiu I." [oiivanci(~)utmb.edu] >>>I am looking for ways of computationally quantifying/estimating >> the donor/acceptor strength of groups connected to larger molecules. If you want transferable substituent quantum indices, or Hammett type indices, see: QSAR Treatment of Electronic Substituent Effects Using Frontier Orbital Theory and Topological Parameters Jonathan J. Sullivan,* A. Daniel Jones, and Kenneth K. Tanji J. Chem. Inf. Comput. Sci., 40 (5), 1113 -1127, 2000. Group electronegativity and Fukui function studies of the substituent effects in aromatic and inorganic systems J. Korchowiec, R. F. Nalewajski International Journal of Quantum Chemistry, Volume 44, Issue 6 , Pages 1027 - 1040 Girones X, Ponec R. Molecular Quantum Similarity Measures from Fermi hole densities: modeling Hammett sigma constants. J Chem Inf Model. 2006 May-Jun;46(3):1388-93. Smith PJ, Popelier PL. Quantum chemical topology (QCT) descriptors as substitutes for appropriate Hammett constants. Org Biomol Chem. 2005 Sep 21;3(18):3399-407 Or better yet, search PubMed http://www.ncbi.nlm.nih.gov/ or Publishers' sites (Wiley,...) or Google >>>...but this property is unable to differentiate between the different >>> positions of the group (meta or para substitution, for example). Well, for mono-substituted benzenes it was easy to develop series of substituent constants for o, m, p, whereas for heterocyclic skeletons it might be difficult, due to the large diversity of reactivity and effects at various positions. This is why Hammett constants or similar substituent indices are no longer a "hot topic" in modeling molecular properties. Ovidiu Ivanciuc Sealy Center for Structural Biology and Molecular Biophysics Department of Biochemistry and Molecular Biology University of Texas Medical Branch 301 University Boulevard Galveston, Texas 77555-0857 USA http://ivanciuc.org Email: oiivanci=-=utmb.edu Email: iejmd=-=yahoo.com IEJMD: http://www.biochempress.com CoEPrA: http://coepra.org