PMID: 19772367;Abstract:
Phthalocyanines (Pcs) are commonly applied to advanced technologies such as optical limiting, photodynamic therapy (PDT), organic field-effect transistors (OFETs), and organic photovoltaic (OPV) devices, where they are used as the p-type layer. An approach to Pc structural diversity and the incorporation of a functional group that allows fabrication of solvent resistant Pc nanostructures formed by using a newly developed nanoimprint by melt processing (NIMP) technique, a variant of standard nanoimprint lithography (NIL), is reported. Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), a click chemistry reaction, serves as an approach to structural diversity in Pc macrocycles. We have prepared octaalkynyl Pc 1b and have modified this Pc using the CuAAC reaction to yield four Pc derivatives 5a-5d with different peripheral substituents on the macrocycle. One of these derivatives, 5c, has photo-cross-linkable cinnamate residues, and we have demonstrated the fabrication of robust cross-linked photopatterned and imprinted nanostructures from this material. © 2009 American Chemical Society.
We report a route to thin-film polymorphs of soluble TiOPc derivatives that exhibit similar near-IR absorptivities as vapor deposited thin-films of the parent TiOPc chromophore (phase-I and phase-II polymorphs) and demonstrate that solution-processed planar and bulk heterojunction solar cells fabricated with one of these derivatives exhibited photoactivity throughout the same near-IR wavelength range without compromising VOC. Solution-processed thin-films of soluble octakis(alkylthio)-substituted TiOPc derivatives 1–3 exhibit absorption extending to 1000 nm. When incorporated into OPV devices, the contributions from the lowest CT excitonic state (QB band) of 1 to device performance were evident in both PHJ and BHJ architectures, indicating sufficient driving force for PIET. This contribution was improved via intimate mixing of donor and acceptor molecules in a BHJ architecture, albeit with a decrease in efficiency. IPCE of the best performing BHJ device revealed a contribution from 1 exceeding that of acceptor PCBM, and extending to 1000 nm.
Quinacridone-cored dendrimers with photocrosslinkable cinnamate moieties on the periphery can be patterned down to 5 micron features while retaining luminescence.
PMID: 20738148;Abstract:
Figure presented. We report a significant improvement in the synthesis of disassembling dendritic structures by using 4-hydroxy-3-nitrobenzoic acid as the building block. We have prepared multigram quantities of first- through third-generation linearly disassembling dendrons containing a [3-N,4-O]-benzylaryl ether disassembly pathway, capped by a vanillin-derived phenyl allyl ether trigger, and a p-nitrophenoxy (PNP) reporter group. The disassembly process of these materials was initiated by allyl deprotection and monitored by the absorbance of the PNP reporter unit in the UV-vis. Modification of the disassembly conditions for the allyl trigger resulted in decreased disassembly times, decreased incubation time for onset of disassembly from minutes to seconds, and allowed observation of indicative rate differences between generations not seen with the previously reported conditions. © 2010 American Chemical Society.
Abstract:
Four dendrimers (1b-4b) containing chiral vicinal diol-based subunits were prepared from their acetonide-protected precursors (1a-4a). The optical activity of these chiral dendritic structures was successfully modeled using structurally similar, low molecular weight model compounds. Using the [Φ](d) values of the low molecular weight model compounds 5b-7b, we calculated [Φ](d) values for dendrimers 1b-4b that agree to within 4.5% of the observed values. Agreement between the optical activity of the model compounds and that of the dendrimers leads to the conclusion that the conformational equilibria of the dendrimer subunits are not perturbed relative to those of the model compounds.
