Template-directed synthesis of pi-conjugated porphyrin [2]rotaxanes and a [4]catenane based on a six-porphyrin nanoring

[2]Rotaxanes consisting of butadiyne-linked porphyrin dimers threaded through a phenanthroline-containing macrocycle, can be synthesised by an active-metal template directed copper-mediated Glaser coupling, in yields of up to 61%, without requiring a large excess of the macrocycle. The crystal structure of one of these rotaxanes confirms that the macrocycle is clasped around the centre of the porphyrin dimer. A radial hexa-pyridyl template was used to convert the alkyne-terminated [2]rotaxane into a [4]catenane cyclic porphyrin hexamer in 62% yield, via palladium-catalysed Glaser coupling. The related [7]catenane porphyrin dodecamer complex was also isolated as a by-product of this cyclisation, in 6% yield. These results illustrate the scope of template-directed synthesis for creating complex interlocked structures directly from simple starting materials. © The Royal Society of Chemistry 2011

Effect of side groups on the vacuum thermal evaporation of polythiophenes for organic electronics

The vacuum thermal evaporation of poly(3-hexylthiophene) (P3HT) and poly(thiophene) (PTh) conductive polymers with and without side groups is reported. The role of side groups in relation to structural and electronic properties is examined. FT-IR and GPC analysis is used to study the effect deposition has on conjugation of the polymer. Topography and grain structure of the polymer films are studied using MicroXAM, AFM and TEM. XRD and TEM data reveal enhanced molecular packing and crystallinity of PTh. This results in significantly improved charge transport properties with relatively high hole mobilities (10 -4 cm 2/Vs). Evaluation of PTh and P3HT electronic properties is performed on simple geometry planar C 60 heterojunction solar cells. PTh/C 60 devices exhibit almost a 70% increase in efficiency as compared to P3HT/C 60 devices, demonstrating enhanced charge collection in PTh films through improved molecular order. © 2012 Elsevier B.V. All rights reserved

Non-traditional cyanines: Candidate materials for all-optical signal processing applications

Development of non-traditional cyanine systems has allowed for improvements in the material properties required for all-optical signal processing applications: enhanced third-order nonlinearity, low nonlinear losses, improved processability, and controlled intermolecular interactions in the solid-state. © 2009 Optical Society of America

Synthesis and two-photon spectrum of a bis(porphyrin)-substituted squaraine.

A chromophore in which zinc porphyrin donors are linked through their meso positions by ethynyl bridges to a bis(indolinylidenemethyl) squaraine core has been synthesized using Sonogashira coupling. The chromophore exhibits a two-photon absorption spectrum characterized by a peak cross section of 11,000 GM and, more unusually, also exhibits a large cross section of >780 GM over a photon-wavelength window 750 nm in width