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

Langmuir and grafted monolayers of photochromic amphiphilic monodendrons of low generations

Genson, K. L., Holzmuller, J., Villacencio, O. F., McGrath, D. V., Vaknin, D., & Tsukruk, V. V. (2005). Langmuir and grafted monolayers of photochromic amphiphilic monodendrons of low generations. Journal of Physical Chemistry B, 109(43), 20393-20402. doi:10.1021/jp0524678

PMID: 16853639;Abstract:

Four generations of monodendrons with multiple dodecyl alkyl tails (AA-N, N representing number of alkyl tails from 1 to 8), an azobenzene spacer group, and a carboxylic acid polar head have been studied at the air-water and air-solid interface using AFM, GIXD, X-ray reflectivity, and UV - vis spectrometry. The one and two tail molecules formed orthorhombic lateral packing with long-range intramonolayer ordering. Good agreement between molecular models and thickness measurements indicated that the one and two tail molecules orient along the surface normal. The increase in the cross-sectional mismatch caused by the presence of the multiple chains for the higher generations disrupted the long-range ordering and forced the alkyl tails to adopt quasi-hexagonal structure. The higher generations (AA-4 and AA-8) formed a kinked structure with the alkyl tails oriented perpendicular to the surface with the azobenzene group tilted at a large degree toward the surface. The photoisomerization behavior in dilute solutions, at the air-water interface, and for grafted layers demonstrated that lower generation monodendrons maintained the photochromic behavior after chemical grafting to the silicon substrates, although the confinement of the molecules in monolayers significantly increased the reorganization time. © 2005 American Chemical Society.

Convergent synthesis of geometrically disassembling dendrimers using Cu(I)-catalyzed C-O bond formation

Polaske, N. W., Szalai, M. L., Shanahan, C. S., & McGrath, D. V. (2010). Convergent synthesis of geometrically disassembling dendrimers using Cu(I)-catalyzed C-O bond formation. Organic Letters, 12(21), 4944-4947. doi:http://doi.org/10.1021/ol102081q

PMID: 20925328;Abstract:

The convergent synthesis of geometrically degradable dendrimers based on the 2,4-bis(hydroxymethyl)phenol subunit is presented. The key step of the synthetic scheme involves the CuI/3,4,7,8-tetramethyl-1,10-phenanthroline- catalyzed coupling of aryl iodides and alcohols. The synthesis and disassembly of these compounds is discussed. © 2010 American Chemical Society.

EAP hydrogels for Pulse Actuated Cell System (PACS) architectures in drug delivery infusion pumps

Plata, R. E., Rogers, H. R., Banister, M., Vohnout, S., & McGrath, D. V. (2008). EAP hydrogels for Pulse Actuated Cell System (PACS) architectures in drug delivery infusion pumps. American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 49(1), 836-837.

Photochromic dendrimers containing six azobenzenes

Liao, L., Junge, D. M., & McGrath, D. V. (2002). Photochromic dendrimers containing six azobenzenes. Macromolecules, 35(2), 319-322.

Low generation photochromic monodendrons on a solid surface

Sidorenko, A., Houphouet-Boigny, C., Villavicencio, O., McGrath, D. V., & Tsukruk, V. V. (2002). Low generation photochromic monodendrons on a solid surface. Thin Solid Films, 410(1-2), 147-158.

Abstract:

Zeroth through third generations of amphiphilic monodendrons containing a benzyl-15-crown-5 polar focal point, photochromic spacer, and alkyl tails as peripheral groups have been investigated for their ability to form photoresponsive surface monolayers. Thickness measurements, scanning probe microscopy, and molecular modeling were used to determine the microstructure of the monolayers. The tilted molecular packing of dendrons in the monolayers is proposed with bulky dendritic shell prohibiting dense packing of azobenzene groups and the aggregate formation. The two-stage trans-cis isomerization was observed for the photochromic monodendron layers composed of various generation dendrons. Fast changes within the first several minutes occurred in the azobenzene-containing monodendrons until the conversion of trans-cis isomerization reaches 13-33%. Then lateral steric hindrances in the monolayer decreases the transformation rate by three orders of magnitude. Diffusion limited intralayer reorganization is suggested to be a limiting factor in the rate of photoisomerization changes. © 2002 Elsevier Science B.V. All rights reserved.

Dominic V Mcgrath