Perylene-Based Materials: Potential Components in Organic Electronics and Optoelectronics

Perylene-based materials, including charge-transport discotic liquid crystals and charge-transfer long-wavelength absorbing chromophores, for potential organic electronic and optoelectronic applications, were designed, synthesized and characterized. Two types of discotic liquid crystals, perylene diimides and coronene diimides, can form columnar liquid crystalline phases over a wide temperature range; many of them can have room-temperature liquid crystalline phases after cooling from isotropic liquid. Their charge transport properties were studied by space-charge limited current method; high charge carrier mobilities, with the highest being up to 6.6 cm2/Vs, were found in liquid crystalline phases of these materials under ambient conditions. Structural variables, including aromatic cores and side groups, were examined to get a certain degree of understanding of charge transport properties in these discotic liquid crystals. It was found that mesophase order can have an important effect on charge carrier mobilities. The discotic liquid crystals with high charge carrier mobilities are serious candidates for use in large-area low-cost applications such as solar cells. Long-wavelength, highly absorbing chromophores, featuring donor-substituted perylene diimides, were generated by a combination of charge-transfer process and conjugation extension. The charge-transfer chromophores are expected to lead to further investigation on their potentials as sensitizers in Grtzel solar cells.Ph.D.Committee Chair: Marder, Seth; Committee Member: Bredas, Jean-Luc; Committee Member: Bunz, Uwe; Committee Member: Kippelen, Bernard; Committee Member: Perry, Josep

Ice-templating of core/shell microgel fibers through 'Bricks-and-Mortar' assembly

通讯作者地址: Stucky, GD (通讯作者), Univ Calif Santa Barbara, Mat Res Lab, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 地址: 1. Univ Calif Santa Barbara, Mat Res Lab, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 电子邮件地址: [email protected] 'bricks-and-mortar' assembly approach can be used to create well-defined fibers on the microscale with alternating organic-inorganic arrangement through a simple ice-templating strategy. ne fibers are constructed from closely packed monodisperse inorganic nanoparticles@PNIPAm core/shelf microgels. A series of functional 'bricks', such as core/shell and hollow nanoparticles are prepared

UCST or LCST? Composition-Dependent Thermoresponsive Behavior of Poly(<i>N</i>‑acryloylglycinamide-<i>co</i>-diacetone acrylamide)

Copolymerization has been widely used to tune the thermoresponsive behavior of water-soluble polymers. However, the observation of both upper and lower critical solution temperature (UCST and LCST) from the same type of copolymer comprising only one monomer whose homopolymer is thermosensitive and the other monomer whose homopolymer is nonthermosensitive has not been reported. In this work, well-defined thermoresponsive copolymers with tunable compositions have been synthesized by copolymerization of <i>N</i>-acryloylglycinamide (NAGA) and diacetone acrylamide (DAAM) via reversible addition–fragmentation chain transfer (RAFT) polymerization. The thermal transitions of these copolymers are investigated using a combination of turbidimetry, dynamic light scattering (DLS), proton nuclear magnetic resonance (¹H NMR), and Fourier transform infrared (FTIR) spectroscopy. The solubility of these copolymers shows a distinct dependence on the composition. While copolymers with up to 30 mol % NAGA are essentially insoluble, copolymers with 35–55 mol % NAGA or 90–100 mol % NAGA have either LCST- or UCST-type transitions respectively, and soluble copolymers are obtained with 60–85 mol % NAGA. The LCST- and UCST-type transitions are tunable with respect to composition, degree of polymerization, polymer concentration, isotope effect and the presence of electrolyte. Insights from variable-temperature ¹H NMR and FTIR spectroscopies reveal the key role of hydrogen-bonding between the NAGA and DAAM units in determining the thermal transitions

Synthesis And Photophysical Properties Of Donor- And Acceptor-Substituted 1,7-Bis(Arylalkynyl)Perylene-3,4:9,10-Bis(Dicarboximide)S

A series of 1,7-bis(arylethynyl)-N,N′-bis[2,6-diisopropylphenyl] perylene-3,4:9,10-bis(dicarboximide)s has been obtained from Sonogashira coupling of the 1,7-dibromoperylene-3,4:9,10-bis(dicarboximide) with p-substituted phenylacetylenes in which the p-substituents include π-donors (dialkylamino, diarylamino, p-(diarylami-no)phenyl, alkoxy) and π-acceptors (diarylboryl, p-(diarylboryl)phenyl). The bis(arylethynyl)-substituted chromophores all show two reversible molecular reductions and are all slightly more readily reduced than unsubstituted perylene-3,4:9,10-bis(dicarboximide)s with the electrochemical potentials being rather insensitive to the π-donor or acceptor nature of the aryl group. The amine derivatives also show reversible molecular oxidations. The UV-vis spectra of the chromophores with alkoxy and boryl substituents show red-shifted absorptions relative to unsubstituted perylene diimides with discernible vibronic structure. In contrast, the lowest energy absorptions of the amino derivatives are broad and structureless, suggesting donor-to-acceptor charge-transfer character. Transient absorption spectra for the amine derivatives were interpreted in terms of ultrafast charge separation, followed by charge recombination on a time scale of ca. 80-2000 ps. Two compounds were also synthesized in which an additional stronger, but more weakly coupled, donor group is linked by a nonconjugated bridge to the p-amine donor, to investigate the effect on the charge recombination lifetimes; however, the lifetimes of the charge-separated states, ca. 150 and 1000 ps, were within the range observed for the simple amine systems. Finally, the two-photon absorption properties of three bis(arylethynyl)-substituted derivatives were investigated, along with those of 1,7-di(pyrrolidin-l-y1)-N,N′-bis[2,6- diisopro-pylphenyl]perylene-3,4:9,10-bis(dicarboximide). As with other perylene-3,4:9,10-bis(dicarboximide)s and related species, strong two-photon absorption (\u3e1000 GM) was observed for three of these species close to the one-photon absorption edge; however, an additional feature (100-500 GM) was also observed at longer wavelength. An example with (p-aminophenyl)ethylnyl substituents showed a qualitatively different two-photon spectrum with a cross-section \u3e500 GM being observed over a broad wavelength range. © 2009 American Chemical Societ

Aqueous Polymerization-Induced Self-Assembly for the Synthesis of Ketone-Functionalized Nano-Objects with Low Polydispersity

Efficient synthesis of functionalized, uniform polymer nano-objects in water with controlled morphologies in one step and at high concentrations is extremely attractive, from perspectives of both materials applications and industrial scale-up. Herein, we report a novel formulation for aqueous reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization based on polymerization-induced self-assembly (PISA) to synthesize ketone-functionalized nanospheres and vesicles. Significantly, the core-forming block was composed entirely of a ketone-containing polymer from a commodity monomer diacetone acrylamide (DAAM), resulting in a high density of ketone functionality in the nano-objects. Producing uniform vesicles represents another challenge both in PISA and in the traditional self-assembly process. Aiming at producing uniform nano-objects, especially vesicles, in such a highly efficient aqueous PISA process, we devised strategies to allow sufficient time for the in situ generated polymers to relax and reorganize into vesicles with a remarkably low polydispersity. Specifically, both reducing the radical initiator concentration and lowering the polymerization temperature were shown to be effective for improving the uniformity of vesicles. Such an efficient, aqueous PISA to produce functionalized and uniform nano-objects with controlled morphologies at solid contents up to 20% represents important progress in the field

One-Enzyme Triple Catalysis: Employing the Promiscuity of Horseradish Peroxidase for Synthesis and Functionalization of Well-Defined Polymers

We demonstrate a new concept in polymer chemistry that the promiscuity of enzymes, as represented by horseradish peroxidase, can be employed for RAFT polymerization and thiol–ene and Diels–Alder reactions to synthesize well-defined functional polymers, via three different catalytic reactions mediated by one single enzyme

Single Monomer for Multiple Tasks: Polymerization Induced Self-Assembly, Functionalization and Cross-Linking, and Nanoparticle Loading

Efficient preparation of multifunctional nano-objects with controlled morphologies in one step at high concentrations is synthetically challenging, yet is highly desirable, in a broad range of materials applications. Herein, we address this synthetic hurdle by introducing a single commodity monomer 2-(acetoacetoxy)­ethyl methacrylate (AEMA) to realize multiple functions. Facile preparation of both nanospheres and vesicles via polymerization induced self-assembly at concentrations of 20–30% provided defined polymeric nanomaterials with reactive handles inherent to the AEMA units. High-yielding keto-alkoxylamine chemistry was utilized to decorate and cross-link the nano-objects. Nanoparticle loading into the designated location within both nano-objects was exemplified with in situ formation of silver nanoparticles. The concept of using a single monomer capable of both morphology control and multifunctionalization is expected to offer significant opportunities in functional nanomaterials