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

Frustration of condensed phase aggregation of naphthalocyanine by dendritic site-isolation

Chen, X., Fernando, N., & McGrath, D. V. (2010). Frustration of condensed phase aggregation of naphthalocyanine by dendritic site-isolation. Macromolecules, 43(13), 5512-5514. doi:http://doi/org/10.1021/ma100902m

Abstract:

The synthesis and aggregation studies of a pair of 3, 4,12,13,21,22,30,31- octasubstituted 2,3-Naphthalocyanine (Ncs) 1 and 2 was reported. The synthetic route leading to these naphthalonitriles started from dimethyl 4,5-dihydroxyphthalate onto which the previously synthesized dendritic alcohols 3 and 4 were introduced through the Mitsunobu protocol. The obtained diesters 6 and 7 were reduced to the corresponding 1,2-dimethanols (8 and 9), and subsequent Swern oxidation provided the disubstituted dendritic phthalaldehydes 10 and 11. Finally, 10 and 11 were converted to naphthalonitriles 12 and 13 through base-promoted condensation with succinonitrile in DMSO. Compounds 1 and 2 were purified by flash column chromatography. Initial molecular aggregation studies were performed in solution as a function of increasing volume fraction of EtOH. The B-bands at 332 and 402 nm exhibited only slight hypochromicity during this change in solvent conditions.

Toward photoresponsive dendritic self-assembly

Hashemzadeh, M., & McGrath, D. V. (1998). Toward photoresponsive dendritic self-assembly. American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 39(2), 338-339.

Abstract:

Tapered dendritic structures with a crown ether receptor moiety and a hydrophobic dendritic sector linked through an azobenzene were prepared and characterized. The dendritic structures exhibit typical azobenzene photoresponsive behavior in solution.

Asymmetric phthalocyanine synthesis by ROMP-capture-release

Chen, X., Salmon, T. R., & McGrath, D. V. (2009). Asymmetric phthalocyanine synthesis by ROMP-capture-release. Organic Letters, 11(10), 2061–2064. doi:http://doi.org/10.1021/ol900352f

Statistical condensation of norbornenyl-tagged phthalonitrile 3 (Pn A) and 4,5-di-4-methoxyphenoxyphthalonitrile 4 (Pn B) followed by ring-opening metathesis polymerization (ROMP) of Pcs AB(3) and B(4) produced asymmetric Pc-appended polymers. Acidic cleavage of the resulting polymers afforded 2,3,9,10,16,17-hexa-(4-methoxyphenoxy)-23-hydroxy Pc 9. A more soluble 2,3,9,10,16,17-hexa-4-pentylphenoxy-23-hydroxy Pc 13 was synthesized by the same strategy and modified with sebacoyl chloride demonstrating that the unmasked hydroxyl site is reactive as a nucleophile.

Hydrobenzoin-based rigid chiral polymer

Bieging, A., Liao, L., & McGrath, D. V. (2002). Hydrobenzoin-based rigid chiral polymer. Chirality, 14(2-3), 258-263.

PMID: 11835572;Abstract:

We prepared a rigid, chiral polymer (1) from optically active hydrobenzoin-based subunits. Nonracemic monomer units 6 and 8 were prepared by asymmetric dihydroxylation (AD) methodology and polymerization was carried out under Sonagashira coupling conditions. Polymer I was obtained in good yield with a molecular weight Mn = 5,100 (PDI = 2.3). Modeling suggests that polymer 1 could form a stable helical mainchain conformation in solution or the solid state. The chiroptical data of the polymer and a low-molecular weight model compound (9) are compared. © 2002 Wiley-Liss, Inc.

The mechanism of aqueous ruthenium(II)-catalyzed olefin isomerization

McGrath, D. V., & Grubbs, R. H. (1994). The mechanism of aqueous ruthenium(II)-catalyzed olefin isomerization. Organometallics, 13(1), 224-235.

Abstract:

Olefin isomerization of allylic ethers and alcohols is catalyzed by Ru^II(H2O)6(tos)2 (tos = p-toluenesulfonate) (1) under mild conditions in aqueous solution to yield the corresponding carbonyl compounds. Non-allylic olefins are also isomerized, although homoallylic alcohols exhibit stability toward isomerization. An exclusive 1,3-hydrogen shift is observed in the isomerization of allyl-1,1-d2 alcohol to propionaldehyde-1,3-d2 and allyl-1,1-d2 methyl ether to 1-propenyl-1,3-d2 methyl ether by 1 in aqueous solution. The presence of crossover products from the isomerizations of mixtures of (a) allyl-3-¹³C alcohol and allyl-1,1-d2 alcohol and (b) allyl-1,1-d2 methyl ether and allyl ethyl ether demonstrates that the isomerization of both alcohols and ethers occurs via intermolecular hydrogen shifts. A modified metal hydride addition-elimination mechanism involving exclusive Markovnikov addition to the double bond directed by the oxygen functionality of the substrate has been proposed. © 1994 American Chemical Society.

Dominic V Mcgrath