One-pot synthesis and AFM imaging of a triangular aramide macrocycle

Macrocyclizations in exceptionally good yields were observed during the self-condensation of N-benzylated phenyl p-aminobenzoates in the presence of LiHMDS to yield three-membered cyclic aramides that adopt a triangular shape. An ortho-alkyloxy side chain on the N-benzyl protecting group is necessary for the macrocyclization to occur. Linear polymers are formed exclusively in the absence of this Li-chelating group. A model that explains the lack of formation of other cyclic congeners and the demand for an N-(o-alkoxybenzyl) protecting group is provided on the basis of DFT calculations. High-resolution AFM imaging of the prepared molecular triangles on a calcite(10.4) surface shows individual molecules arranged in groups of four due to strong surface templating effects and hydrogen bonding between the molecular triangles

A study on the molecular weight of the chloro-precursor polymer to MEHPPV

The observed molecular weight of the chloro-precursor polymer, 1, to poly[2-(2'-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEHPPV) was found to decrease with decreasing polymer concentration when measured by gel permeation chromatography with the decrease probably being due to the dissociation of polymer aggregates or physical networks

SNAP - a three dimensional neutron diffusion code

SIGLEAvailable from British Library Document Supply Centre- DSC:Alphafiche(AEA-RS--1214) / BLDSC - British Library Document Supply CentreGBUnited Kingdo