Subject: Visualization of COSMO polarization charge densities and logP

From: "Dr. Andreas Klamt" <[email-masked]>
Date: Fri, 15 Dec 2000 09:59:13 +0100

Dear Colleagues,

I like to inform you about novel way of visualizing COSMO polarization charge densities and of thermodynamic properties like
logP on the molecular surface. 

As I pointed out in my COSMO-RS papers (for references see http://www.cosmologic.de) the polarization charge density sigma of a
molecule embedded in a conductor is a very good, local descriptor for molecular interactions in solution. Indeed it is an even
better descriptor than electrostatic potential (ESP), because ESP is rather longe-ranging while interactions are more local. As
an example consider a surfactant with a positively charged head group. ESP shows a positive sign on the entire alkane chain of
the surfactant, although this alkane chain behaves like a normal alkane chain. In contrast, the polarization charge density
sigma shows high polarity on the head group, but describes the alkane chain just as a normal alkane chain. As demonstrated in my
COSMO-RS work, even hydrogen bonding and "hydrophobicity" can be described by sigma. Hence sigma is the most important
interaction descriptor which should be studied on the surface of molecules to analyse their physicochemical behaviour.

Our next release of COSMOtherm will be able to generate high quality VRML visualizations of sigma on the molecular surface. Find
a bunch of example WRL-files on our homepage:

http://www.cosmologic.de/visual.html

As COSMO-RS/COSMOtherm calculates physicochemical properties like logP as a surface integral of a function of sigma, it is
trivial for us to visualize any such property on the molecular surface. Thus you can study such properties as a function of
chemical structure and of conformation, without any restriction by missing fragments. Examples for logP are given on the
homepage as well.

Have fun with the colorful pictures.

Best regards

Andreas Klamt

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Dr. Andreas Klamt
COSMOlogic GmbH&CoKG
Burscheider Str. 515
51381 Leverkusen, Germany

Tel.: 49-2171-73168-1  Fax: ...-9
e-mail: [email-masked]
web:    www.cosmologic.de
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