Dominic V Mcgrath
Publications
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.
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.
Abstract:
A variety of transformations involving C-C bond cleavage in iridium complexes is described. 1,1-Dimethylcyclopentane reacts with [IrH2(Me2CO)2L2]SbF6 (L = (p-FC6H4)3P, 1) to give first [(5,5-C5H4Me2)IrL2]SbF6 (2) and then [(MeC5H4)IrMeL2]SbF6 (3). The corresponding 5,5-dimethylcyclopentadiene gives 1,2- and 1,3-diethylcyclopentadienyl complexes by a route that involves alkyl migration from ring to metal and back. 4,4-Dimethylcyclopentene also reacts to give 3 but the 3,3-isomer follows a different path to give [(MeC5H4)IrHL2]SbF6. Crystal structures of two diene complexes of type 2 are reported and mechanisms for the reactions observed are proposed. © 1986 American Chemical Society.