Dominic V Mcgrath
Publications
Abstract:
Conditions for the self-metathesis assembly of dendrons with alkenyl focal points into dendrimers are developed. Assembly of more complex central cores is the subject of current efforts. Olefin metathesis has become a powerful method in organic synthesis. Several ruthenium-based alkylidiene complexes have led to considerable success in the ring-opening metathesis and ring-closing metathesis reactions in application to the total synthesis of natural products. A preliminary study on the use of metathesis to assemble benzyl aryl ether dendrimers is reported. Self-metathesis yielding dendrimers is observed and the effects of solvent, temperature and reaction conditions on final product yield is optimized.
Abstract:
The ring-opening metathesis polymerization (ROMP) of strained cyclic olefins is an important application of the olefin metathesis reaction. We have shown that the aqueous ROMP of exo-N-Methyl-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide yields a high molecular weight, thermally stable polymer with a low polydispersity in high yields under mild conditions. The mechanical properties and possible applications of these polymers are currently being investigated.
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.
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