Brief Research Description as listed in home pages of the Department of Chemistry.
Research results have been documented in Publications & Patents


The theoretical and computational studies are generously supported by MU Campus Computing. The Silicon Graphics Computing Resources at MU include a Silicon Graphics Power Challenge L supercomputer with 8 R10000 processors. This system is called Shiva and it is our main resource for performing high level ab initio quantum-chemical studies. Senior computer programmer analyst Hossein Tahani assists with the installation, maintenance, and optimization of the various codes we run on Shiva. Our local computing environment in the group also includes Silicon Graphics systems and Mahtaj Khamneian has helped us keeping the system software on our Indigo up-to-date.




Density Color-Coded Gradient Vector Fields
Dr. Rainer Glaser and David Farmer
Department of Chemistry
The figure (click to enlarge) shows an electron density color-coded gradient vector field of the electrostatic complex formed betweeen benzyl cation and dinitrogen. The plot was generated with software written by David Farmer and Rainer Glaser. The new technique for the graphical analysis of electron density distributions was employed recently in a paper entitled "The Cation-Dinitrogen Interaction in "Benzyldiazonium Ion". Preferential Electrostatic Complex Formation and Dinitrogen Catalysis of Benzyl Cation Rotational Automerization " which was written by Rainer Glaser and David Farmer and published in Chem. Eur. J. 1997, 3, 1244-1253. The article appeared in the August issue and our contribution was featured on the cover of the August issue of Chemistry. We also recently presented a poster entitled "Graphical Analysis of Cation-Dinitrogen Interactions with Density Color Coded Gradient Vector Fields" at an ACS Meeting.


Crystal
Lattice
Energies
Numerical Simulation of Molecular Crystals
Dr. Rainer Glaser, Department of Chemistry
Don Steiger and Dr. Calvin Ahlbrandt, Department of Mathematics
We are interested in the numerical simulation of crystals. The success of the quest for novel crystalline materials with interesting electric and optical properties is largely determined by the mode in which the molecules aggregate in the solid state. In crystal engineering one attempts to design and realize lattice architectures in a rational fashion. To do so one needs to know about intermolecular interaction energies. In this context, we are developing methods for the quantitative analysis of electrostatic interactions in crystals. An abstract and a full poster of a recent presentation on the topic "Mathematical Derivation of an Alternative Fast Multipole Method" are available.


Organic Crystalline Ferroelectic Materials
Dr. Rainer Glaser and Michael Lewis
Department of Chemistry

By way of a combination of ab initio computations and experimentation, we are designing NLO chromophores as the building blocs of organic crystalline ferroelectic materials. A few prototypes have been reduced to practice and current efforts are directed at increasing the lattice energies. The picture shows a pair of perfectly dipole parallel-aligned azines molecules. (Click the picture to download a pdb file for viewing with Rasmol.) These pairs assemble in the solid state in such a way as to result in near-perfect dipole parallel alignment of the crystal. These asymmetrically substituted azines therefore not only are NLO chromophores but they also pack in such a way as to render the crystal NLO active without any need for electric field poling. Unprecedented NLO chromophore densities have been realized in this way. The first prototype of a near-perfect organic ferroelectric was featured as the Molecule of the Month, December 1997. This feature can be viewed both as a CHIME version and as an HTML-only version. The Molecule of the Month page is maintained by Paul May of Bristol University.


log(kx/k0) =
sigmaF rohF + sigmaR rohR
with rohR / rohF < 0
Dual Substituent Parameter Relations in Dediazoniation Reactions.
Dr. Rainer Glaser and Stephanie Nelson, MU, Department of Chemistry
Dr. Heinrich Zollinger, ETH Zuerich, Switzerland
The combination of physical-organic and theoretical methods allows one to carry electronic structure analysis to a level that could not be reached by either one approach alone. We have been focusing on studies of "Opposing Sign Reaction Constants in Dual Substituent Parameter (DSP) Relations". The abstract is available online of a lecture that was presented at the 30th Midwest Theoretical Chemistry Conference, University of Illinois, Urbana-Champaign, May 22-24, 1997. For more detail, please refer to a first communication with the title "Electron Density Relaxation and Opposing Sign Reaction Constants in Dual Substituent Parameter Relations in Dediazoniation Reactions" has recently been published in Angewandte Chemie (Angew. Chem. Int. Ed. Engl. 1997, 36, 2210-2213).


Deamination of Guanine.
Dr. Rainer Glaser and Sundeep Rayat
MU, Department of Chemistry
The deamination of guanine in vivo and in vitro has long been thought to involve the hydrolysis of an intermediate guanine diazonium ion to form xanthine. The group of Makino found that substantial amounts of oxanosine also are formed in this deamination and this experimental result put in question the generally accepted deamination mechanism for guanine. Research in the Glaser group revealed that the dediazoniation of guanine is accompanied by a facile pyrimidine ring opening reaction. This discovery suggests a hypothesis for the formation of oxanosine and xanthine at the same time. The mechanism proposal has been published in a communication entitled "Pyrimidine Ring Opening in the Unimolecular Dediazoniation of Guanine Diazonium Ion. An ab Initio Theoretical Study of the Mechanism of Nitrosative Guanosine Deamination" in the Journal of the American Chemical Society (J. Am. Chem. Soc. 1996, 118, 10942-10943). Current research aims at establishing the mechanism of guanine deamination via a combination of experimental and theoretical methods.


PolyPhenyl Structures and Vibrational Properties of Polyphenyls
Dr. Rainer Glaser, MU, Dept. of Chemistry
Dr. Meera Chandrasekhar and Dr. Sushismita Guha, MU Dept. of Physics & Astronomy
We are studying the structures and vibrational properties of biphenyl and polyphenyls and of their aggregates. The results of these studies will answer questions relating to arene-arene interactions and might help to explain Raman intensity changes observed in the solid as a function of pressure.


Nucleophilic Substitution of Diazonium Ions.
Dr. Rainer Glaser and Rhonda Walsh, MU, Department of Chemistry


Asymmetrization of Azines and Butadienes.
Dr. Rainer Glaser and Sarah Meyer, MU, Department of Chemistry


Optical Properties of Azines.
Dr. Rainer Glaser and Heather Tluczek, MU, Department of Chemistry