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

Synthesis and chiroptical analysis of optically active chiral shell dendrons

Junge, D. M., Wu, M., McElhanon, J. R., & McGrath, D. V. (2000). Synthesis and chiroptical analysis of optically active chiral shell dendrons. Journal of Organic Chemistry, 65(17), 5306-5314.

Abstract:

We have prepared a series of chiral dendrons (1-4) in which chiral subunits are placed in individual generational shells at varying distances from the focal point. The optical activity of these chiral dendritic structures is successfully modeled using structurally similar low-molecular weight model compounds. In dendrons 1a and 1b a chiral subunit is directly adjacent to the focal point, whereas in dendrons 2, 3, and 4a,b the chiral subunits are incorporated in the interior of the dendron. A marked difference in optical activity between the former (1a and 1b) and latter (2, 3, 4a,b) dendrons is mirrored in the optical activities of model compounds 12a, 12b, 19a, and 19b. These model compounds directly mimic the surrounding constitution of the chiral subunits in the dendrons. This successful analysis of the chiroptical data using low-molecular weight model compounds suggests that these dendrons do not possess conformational order in solution.

Photoresponsive dendrimers

Junge, D. M., & McGrath, D. V. (1998). Photoresponsive dendrimers. American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 39(2), 340-341.

Abstract:

The photoresponsive behavior of dendrimers with methyl ester exteriors and azobenzene linkers were studied. Saponification of dendrimer 6 was also accomplished to provide a water soluble dendrimer with a hydrophobic interior.

Photoswitchable Flexible and Shape-Persistent Dendrimers: Comparison of the Interplay between a Photochromic Azobenzene Core and Dendrimer Structure

Liao, L., Stellacci, F., & McGrath, D. V. (2004). Photoswitchable Flexible and Shape-Persistent Dendrimers: Comparison of the Interplay between a Photochromic Azobenzene Core and Dendrimer Structure. Journal of the American Chemical Society, 126(7), 2181-2185. doi:http://doi.org/10.1021/ja036418p

PMID: 14971953;Abstract:

Two analogous classes of dendrimers with a single azobenzene moiety at the core have been prepared. Flexible benzyl aryl ether dendrimers 1a-e were obtained in good yields by direct alkylation of diphenolic azobenzene 3 with benzyl aryl ether dendrons [G-n]-Br (n = 0-4). In rigid dendrimers 2a-e, the azobenzene configurational switch was linked to phenylacetylene dendrons through acetylenic linkages to maintain the shape-persistent nature of these dendrimers. A comparison of these two different classes of dendrimers with azobenzene cores reveals a difference in the properties of the photochromic moiety upon dendritic incorporation as well as a significant difference in the photomodulation of dendrimer properties. The E → Z photoisomerization quantum yield decreased markedly with increasing generation for dendrimers 1a-e but only slightly for dendrimers 2a-e. However, increasing generation did not significantly alter thermal isomerization kinetics or activation barriers. The hydrodynamic volumes of azobenzene-containing dendrimers 2b-e were significantly modulated when the azobenzene unit is subjected to irradiation, while those of dendrimers 1b-e were only slightly affected.

Shape-persistent azobenzene-containing dendrimers

Liao, L., & McGrath, D. V. (2000). Shape-persistent azobenzene-containing dendrimers. American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 41(1), 870-.

Abstract:

Azobenzene-containing shape-persistent dendrimers were synthesized to address the effect of the dendrimer subunit on the behavior of well-defined systems. The resulting dendrimers have rigid structures with phenylacetylene subunits. The properties of the dendrimers allow comparison with previously-prepared flexible azobenzene-containing dendrimers.

Synthesis and characterization of new amine-imine ligands based on trans-2,5-disubstituted pyrrolidines

Sweet, J. A., Cavallari, J. M., Price, W. A., Ziller, J. W., & McGrath, D. V. (1997). Synthesis and characterization of new amine-imine ligands based on trans-2,5-disubstituted pyrrolidines. Tetrahedron Asymmetry, 8(2), 207-211.

Abstract:

We present a modular synthesis of a new class of chiral N,N-chelating ligands containing the C2-symmetric trans-2,5-disubstituted pyrrolidine moiety linked to a pyridine ring. (-)-2-[(2R,5R)-2,5-Dimethylpyrrolidin-1-ylmethyl]pyridine (11, (R,R)-MePMP), (-)-2-[2((2R,5R)-2,5-dimethylpyrrolidin- (12, (R,R)-MePEP), and (+)-2-[(2R,5R)-2,5-diphenylpyrrolidin-1-ylmethyl]pyridine (13, (R,R)-PhPMP) have been prepared. The X-ray structure of the (Λ³-allyl)Pd complex of (R,R)-MePMP (11) is reported.

Dominic V Mcgrath