Dominic V Mcgrath

Professor, Chemistry and Biochemistry-Sci

Professor, BIO5 Institute

Primary Department

Chemistry & Biochemistry

Department Affiliations

Chemistry & Biochemistry

BIO5 Institute

Contact

(520) 626-4690

mcgrath@u.arizona.edu

Research Interest

Dominic Mcgrath, PhD, set forth a program which involves the use of organic synthesis for the design, development, and application of new concepts in macromolecular, supramolecular, and materials chemistry. Research efforts span a number of areas in the chemical sciences and include studies of: 1) chiral dendritic macromolecules and the effect of chiral subunits on dendrimer conformation, 2) photochromic dendrimers and linear polymers which undergo structural changes in response to visible light, 3) liquid crystalline materials based on dendritic and photochromic mesogens, and 4) synthesis of new ligands based on saturated nitrogen heterocycles.A continuing interest remains in the effect of structural perturbations on the properties and functional of dendritic macromolecules. Part of this research addresses the design, synthesis, and study of dendrimeric materials containing chiral moieties in the interior for influencing the conformational order of these 3-dimensional macromolecules. An ultimate goal is to develop materials active for the selective clathration of small guest molecules. Potential applications include chemical separations, sensor technology, environmental remediation, and asymmetric catalysis.Dr. Mcgrath and his lab team recently developed several new classes of dendritic materials containing photochromic subunits. As nature uses light energy to alter function in photoresponsive systems such as photosynthesis, vision, phototropism, and phototaxis, they use light energy to drive gross topological or constitutional changes in fundamentally new dendritic architectures with precisely placed photoresponsive subunits. In short, they can drive dendrimer properties with light stimuli. Two entirely new classes of photoresponsive dendritic macromolecules have been developed and include: 1) photochromic dendrimers and 2) photolabile dendrimers. Dr. Mcgrath anticipates that switchable and degradable dendrimers of this type will have application in small molecule transport systems based on their ability to reversibly encapsulate guest molecules. He continues to develop these materials as potential transport hosts and photoresponsive supramolecular assemblies.

Publications

Geometric Disassembly of Dendrimers: Dendritic Amplification

Szalai, M. L., Kevwitch, R. M., & McGrath, D. V. (2003). Geometric Disassembly of Dendrimers: Dendritic Amplification. Journal of the American Chemical Society, 125(51), 15688-15689. doi:http://doi.org/10.1021/ja0386694

Synthesis and degradation of photolabile dendrimers based on o-nitrobenzyl ether photolabile cores

Kevwitch, R. M., & McGrath, D. V. (2007). Synthesis and degradation of photolabile dendrimers based on o-nitrobenzyl ether photolabile cores. New Journal of Chemistry, 31(7), 1332-1336. doi:http://doi.org/10.1039/b617289j

Abstract:

Two dendrimer cores, 1a and 2a, that contain o-nitrobenzyl photolabile moieties, lack hydrolytically sensitive ester linkages and possess three and six sites for dendron attachment, respectively, have been alkylated to provide methylated core analogs 1b and 2b as well as second-generation benzylaryl ether dendrimer 1c and third-generation dendrimer 2c. These dendrimers undergo clean photocleavage as indicated by the evolution of isosbestic points in the UV spectra during photolysis. In addition, the nature of the photodegradation products was confirmed by observing the photolyses by both ¹H NMR and GPC. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

Toward an understanding of the high enantioselectivity in the osmium-catalyzed asymmetric dihydroxylation. 4. Electronic effects in amine-accelerated osmylations

Nelson, D. W., Gypser, A., Ho, P. T., Kolb, H. C., Kondo, T., Kwong, H., McGrath, D. V., Rubin, A. E., Norrby, P., Gable, K. P., & Sharpless, K. B. (1997). Toward an understanding of the high enantioselectivity in the osmium-catalyzed asymmetric dihydroxylation. 4. Electronic effects in amine-accelerated osmylations. Journal of the American Chemical Society, 119(8), 1840-1858.

Abstract:

Electronic effects in osmylation reactions accelerated by pyridine and quinuclidine derivatives were investigated by varying the substituents on the amine ligand as well as on the alkene substrate. Ligand substituent effects were gauged by determination of the equilibrium constants for coordination of the amines to OsO4, evaluation of structural properties and reduction potentials of the amine-OsO4 complexes, and analysis of the kinetics of osmylations in the presence of the amines. Substrate substituent effects were gauged by kinetic Hammett studies using several different amine/alkene combinations. Nonlinear Hammett relationships resulting from alkene substituent effects were observed, and the deviation from a linear free energy relationship was found to depend on the structure, binding capacity, and concentration of the amine. The results were evaluated in terms of the contending '[3 + 2]' and '[2 + 2]' mechanisms currently under consideration. A change in mechanism that depends on the structural and electronic properties of both alkene and amine is proposed.

Driving dendrimers with light: Dendrimers with azobenzene central linkers

McGrath, D. V., & Junge, D. M. (1999). Driving dendrimers with light: Dendrimers with azobenzene central linkers. Macromolecular Symposia, 137, 57-65.

Abstract:

Several new classes of azobenzene-containing dendrimers have been prepared and characterized. Three central linker azobenzenes, p-(p'-hydroxyphenylazo)phenol (A), aniline p-(p'-chlorocarbonylphenylazo)benzoyl chloride (B), and p-(p'-aminophenylazo) (C) were reacted with the appropriate dendritic fragment ([Gn]Br for A and C; [Gn]OH for B) to yield dendrimers 1-3 of varying generational size. The photoresponsive characterization of these dendrimers illustrates the insensitivity of the photoresponsive behavior of the azobenzene with respect to the nature of the attached dendritic fragment.

Driving dendrimers with light

McGrath, D. V., Junge, D. M., McElhanon, J. R., & Hashemzadeh, M. (1998). Driving dendrimers with light. American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 39(2), 281-282.

Abstract:

New dendrimers with azobenzene central linkers were prepared and their photoresponsive behavior demonstrated. The rates and activation energies of the thermal cis-trans isomerization of a series of dendrimers of increasing size illustrate the insensitivity of the photoresponsive behavior of the azobenzene with respect to the nature of the attached dendritic fragment.

Dominic V Mcgrath