Office: PHSC 302B Phone: (405) 325-3834 Email: dtglatzhofer@ou.edu Full Publications List

Daniel T. Glatzhofer Professor of Chemistry and Biochemistry B.S.(Denison University) 1979 Ph.D. (University of Michigan) 1984. Max-Planck-Institute for Polymer Science Fellow, Germany, 1984-1986 Postdoctoral Researcher (Ohio State University) 1987-1988 OU AMOCO Teaching Award, 1996. Regent's Award for Superior Teaching, 2001 Kinney-Suggs Award - Outstanding Professor in the College of Arts and Sciences, 2002 President's Associates Presidential Professor 2004-2008

Division: Organic and polymer chemistry Research Interests Synthesis and electronic properties of organic and organometallic materials, especially polymers; conducting and photoconducting polymers, polymer electrochemistry; charge transfer salts. Cyclophane chemistry. Metal arene chemistry.

Research Description      

Our group's research interests lie primarily in the use of organic, organometallic, and polymer chemistry to design, synthesize and characterize new materials with unique and potentially useful electronic properties, especially in the solid state.  Electronic properties are meant here in a broad sense and along with synthesis, special interest is given to the electronic (conductivity, photoconductivity and magnetic), optical (absorption, fluorescence), electrochemical (ionic conductivity, electropolymerization and redox behavior), and physical (structure, morphology) characterization of these materials.  We are also developing new synthetic methods based on fundamental organic and organometallic chemistry.  Our current interests can be divided into 4 general project categories:

Lithium batteries comprise a multi-billion dollar industry worldwide.  Continued growth and improvement on current lithium battery technology hinges on the development of solid polymer electrolyte systems with high ionic conductivity and good chemical and mechanical stability to function as separators.  Mixtures of poly(ethyleneoxide) (PEO) or its variants with lithium salts have dominated research in this area.  It is generally accepted that to have high ionic conductivity the polymer must interact with the lithium ion strongly enough to allow the formation of charged species that can be mobile (as opposed to neutral ion pairs) and must possess sufficient flexibility to allow ion transport through the solid polymer matrix. PEO/salt mixtures typically suffer from two major drawbacks:  1) formation of crystalline, stoichiometric compounds that restrict mobility and decrease conductivity and 2) poor physical properties.  Together with the group of Prof. Roger Frech (Physical Chemistry - IR and Raman spectroscopy), we have shown that, unlike PEO, poly(ethylenimine) (PEI) progressively disorders with the addition of lithium triflate and conductivity, which appears to occur by two distinct mechanisms in PEI, does not drop precipitously with increasing salt concentration.  We are currently synthesizing structural variants of PEI to explore structure/property relationships and investigate the factors that control speciation and ion mobility in these systems on a molecular level.  Since the nitrogen atoms in PEI can be protonated, we are also looking at these materials as potential proton-conducting solid polymer electrolytes for fuel cell applications.

There are few direct routes known for the monohydroxylation of aromatic rings to form phenols. Possibly the most common general, but indirect, route to phenolics is by conversion of aromatic amino groups (available from nitration/reduction) to hydroxyl groups using Sandmeyer chemistry (diazotization/substitution by water).  However, the Sandmeyer hydroxylation has several problems associated with it and a perusal of the literature shows poor yields predominate. We have previously shown that aromatic amides can be converted to esters via N-nitrosamide intermediates.  The reaction is believed to proceed by rearrangement of the aromatic N-nitrosamide to an N-acyloxyazoaromatic, followed by loss of nitrogen gas through a homolytic cleavage mechanism.  The resulting aromatic and acyloxy radicals couple to give the desired ester in 80 - 97 % yield for a wide range of functionalized aromatics.  These esters can be quantitatively transformed to phenols by simple transesterification.   In exploring the scope of this reaction we have discovered that treatment of the aromatic nitrosamides (which are generated in situ) with iodide, bromide or benzene gives the corresponding aromatic halide or biphenyl in >65% yields.  Treatment of the aromatic nitrosamide with reactive monomers, such as methyl methacrylate, result in polymerization with the aromatic ring being incorporated as a polymer end group.  The mechanisms, scope, and utility of these reactions are being explored and expanded.

The small ring cyclophanes (bridged aromatic rings) such as [2.2]paracyclophane have long been of interest because they exhibit non-conjugated, through-space electronic interactions between their cofacial benzene rings but these effects have seldom been exploited.  It has been reported that several polymers containing cyclophane rings exhibit unusual electronic properties, most notably when treated with various modifiers (oxidants, dopants, etc.).  Of particular interest, we have discovered that with strong electron acceptors, these types of polymers form charge-transfer complexes that have good physical properties and exhibit unusually strong photoconducting behavior. However, the mechanism and scope of energy transport phenomena in these (and related) polymer systems remain largely unexplored.  Such materials are of interest for photosensor, photocopying, and energy conversion applications and collaborations in these areas with physicists and electrical engineers within the University are ongoing.

The [2.2]Paracyclophanes are inherently highly strained (ca. 30 Kcal/mole), although kinetically stable, molecules.  We have been synthesizing highly nitrated cyclophanes and investigating their decomposition behavior to evaluate their potential utility as energetic materials.  Several of the compounds we've synthesized decompose much more energetically than current theories on the decomposition of nitroaromatics would predict and which cannot be entirely explained by the strain energy, suggesting a unique decomposition mechanism.

We are also actively investigating exploitation of the chirality of substituted [2.2]paracyclophanes, resulting from their structural rigidity, to form new chiral ligands such as 5 for the formation of metal complexes for asymmetric catalysis, e. g. asymmetric cyclopropanation.  Copper(II) complexes of some of these ligands are particularly of interest and have shown high catalytic cyclopropanation efficiencies and good enantioselectivities of up to 67% ee.

Other projects in our group include the use of cyclopentadienylmetal cations to stabilize highly reactive benzoquinodimethanes and other reactive organic intermediates as h⁶-ligands, to allow their characterization and use in synthesis and polymerization.  Conversely, we are investigating the use of  h⁶-complexation of metals to polycyclic arenes to activate normally unreactive aromatic hydrocarbons. 

Finally, we are investigating the use of surfactants to pre-organize monomers for electropolymerization to form electrically conducting polymes from aqueous solutions. 

M. Erickson, D. T. Glatzhofer, and R. Frech, "Gel electrolytes based on crosslinked tetraethylene glycol diacrylate/poly(ethylenimine) systems", Polymer, 45, 3389-3397 (2004).