Dominic V Mcgrath
Publications
Abstract:
Two dendrimer cores, 5 and 12, containing o-nitrobenzyl photolabile moieties have been synthesized from piperonal in five and eight steps, respectively. Methylated core analogs 6 and 13 undergo clean photocleavage as indicated by the evolution of isosbestic points in the UV spectra during photolysis and the observation of degradation products by 1H NMR. These dendrimer cores serve as precursors to dendrimer-based photodegradable materials.
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.
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.
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.
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.