Our research program involves the use of organic synthesis for the design, development, and application of new concepts in macromolecular, supramolecular, and materials chemistry. Our research efforts span a number of areas in the chemical sciences and include studies of (a) materials for solar energy conversion, (b) macromolecular systems that undergo structural changes in response to visible light and other stimuli, and (c) the influence of dendritic components of nanoscopic systems on phonic and electronic properties of materials.
We have 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, we use light energy to drive gross topological or constitutional changes in fundamentally new dendritic architectures with precisely placed photoresponsive subunits. In short, we can drive dendrimer properties with light stimuli. We have developed two entirely new classes of photoresponsive dendritic macromolecules: (1) Photochromic Dendrimers, and (2) Photolabile Dendrimers. We anticipate 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. We are continuing to develop these materials as potential transport hosts and photoresponsive supramolecular assemblies.
Our interest in labile macromolecular structures has led to our development of the process of dendrimer disassembly, whereby a triggering stimulus initiates an electronic cascade cleavage of dendritic structures into individual dendrimer subunits or larger dendrimer fragments. This chemistry introduces a new paradigm for the use of dendritic structures based on (1) the nature of dendrimers as covalent assemblages of active species, and using the chemistry of disassembly to release these species into a system; and (2) the role of dendritic components of a system in influencing solubility, energy harvesting, or insulating capabilities, etc., and using the chemistry of disassembly to reverse those contributions to a system. This is a powerful construct, in that dendrimers and dendritic structures can be made up of a wide variety of subunits, compatibilized with many different environments, and incorporated into countless systems. We anticipate that dendritic materials with disassembly capabilities will (a) be useful for traditional polymer degradation technologies, and (b) have potential applications in nanotechnology, biomedicine, sensors, etc.
Reduced aggregation of a quinacridone core in dendrimers of increasing generation enhances solid state luminescence efficiency [Chem. Commun. 2005 444]
"Solution Processed Titanyl Phthalocyanine Derivatives as Donors in Solar Cells: Photoconversion to 1000 nm," Mayukh, M.; Macech, M.; Placencia, D.; Cao, Y.; Armstrong, N.R.; McGrath, D.V. ACS Appl. Mater. Interfaces 2015, 7, in press.
“Modification of alkyne-functionalized asymmetric phthalocyanines by CuI-catalyzed azide-alkyne cycloaddition,” Chen, X.; Lu, C.-W.; Huang, Y.; McGrath, D.V. Tetrahedron 2015, 71, 9154-9160.
"Asymmetric ZnPc-TEG photosensitizers: The effect of Pc substitution on phototoxicity," Muli, D.K.; Rajaputra, P.; You, Y.; McGrath, D.V. Tetrahedron Lett. 2015, 56, 6236-6239.
“Influence of Molecular Orientation on Charge Transfer Processes at Phthalocyanine/Metal Oxide Interfaces and Relationship to Organic Photovoltaic Performance,” Lin, H.-C.; MacDonald, G.A.; Shi, Y.; Polaske, N.W.; McGrath, D.V.; Marder, S.R.; Armstrong, N.R.; Ratcliff, E.L.; Saavedra, S.S. J. Phys. Chem. C 2015, 119, 10304-10313.
"Dendritic Near-IR Absorbing Zinc Phthalocyanines for Antimicrobial Photodynamic Therapy," Muli, D.K.; Carpenter, B.; Ghiladi, R.; McGrath, D.V. Tetrahedron Lett. 2015, 56, 3541-3545.
"Asymmetric ZnPc-Rhodamine B conjugates for mitochondrial targeted photodynamic therapy," Muli, D.K.; Rajaputra, P.; You, Y.; McGrath, D.V. Bioorg. Med. Chem. Lett. 2014, 36, 4496-4500.
"Electron Transfer Processes in Zinc Phthalocyanine-Phosphonic Acid Monolayers on ITO: Characterization of Orientation and Charge Transfer Kinetics By Waveguide Spectroelectrochemistry," Lin, H.-C.; Polaske, N.W.; Oquendo, L.E.; Gliboff, M.; Knesting, K.M.; Nordlund, D.; Ginger, D.S.; Ratcliff, E.L.; Beam, B.M.; Armstrong, N.R.; McGrath, D.V.; Saavedra, S.S. J. Phys. Chem. Lett. 2012, 3, 1154-1158.
"Vanillin and o-vanillin oligomers as models for dendrimer disassembly," Kevwitch, R.M.; Shanahan, C.S.; McGrath, D.V. New J. Chem. 2012, 36, 492-505.
"Phosphonic Acid Functionalized Asymmetric Phthalocyanines: Synthesis, Modification of Indium Tin Oxide (ITO), and Charge Transfer," Polaske, N.W.; Lin, H.-C.; Tang, A.; Mayukh, M.; Oquendo, L.E.; Green, J.T.; Ratcliff, E.R.; Armstrong, N.R.; Saavedra, S.S.; McGrath, D.V. Langmuir 2011, 25, 14900-14909.
"Thermally Reversible Dendronized AB Step-Polymers via "Click" Chemistry," Polaske, N.W.; McGrath, D.V.; McElhanon, J.R. Macromolecules 2011, 44, 3203-3210.
"Peripheral Substitution of a Near-IR Absorbing Soluble Phthalocyanine Using 'Click' Chemistry," Mayukh, M.; Lu, C.-W.; Hernandez, E.; McGrath, D.V. Chem. Eur. J. 2011, 17, 8472-8478.
"Solvent-Free Synthesis of Soluble, Near-IR Absorbing Titanyl Phthalocyanine Derivatives," Mayukh, M.; Sema, C.M.; Roberts, J.M.; McGrath, D.V. J. Org. Chem. 2010, 75, 7893-7896.
"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. Org. Lett. 2010, 12, 4944-4947.
"Polymeric Endoaortic Paving (PEAP): Thermomechanical and Degradation Properties of Polycaprolactone/Polyurethane Blends for Cardiovascular Applications," Ashton, J.H.; Mertz, J.A.; Harper, J.L.; Slepian, M.J.; Mills, J.L.; McGrath, D.V.; Vande Geest, J.P. Acta Biomaterialia 2010, 7, 287-294.
"Improved Iterative Synthesis of Linearly Disassembling Dendrons," Ortiz, A.; Shanahan, C.S.; Sisk, D.T.; Perera, S.C.; Rao, P.; McGrath, D.V. J. Org. Chem. 2010, 75, 6154-6162.
"Frustration of Condensed Phase Aggregation of Naphthalocyanine by Dendritic Site-Isolation," Chen, X.; Fernando, N.; McGrath, D.V. Macromolecules 2010, 43, 5512-5514.