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Self-Assembly of Aluminum- and Gallium-Based <i>meso</i> -Metallaporphyrins
摘要： The molecular meso-metallaporphyrin has been obtained from the reaction of AlMe3 with the bulky 4,5-(Ph2(HO)C)2-1,2,3-triazole (1). The presence of Al?Me groups coordinated to the triazole rings creates three different stereoisomers that were identified by single-crystal X-ray diffraction. Further studies revealed that, for steric reasons, only one of the two main stereoisomers is active in the polymerization of ε-caprolactone. When GaMe3 is used instead of AlMe3, a trimetallic species is formed instead of the meso-metallaporphyrin pointing to a metal-directed self-assembly. On the other hand, the reaction of the monolithium salt [{Li(THF)2}{κ2-N,N′-4,5-(Ph2(HO)C)-1,2,3-triazole}]2 (2; THF = tetrahydrofuran) with MCl3 (M = Al, Ga) yields meso-metallaporphyrin species with a lithium atom in the center of the metallacycle. While the gallium derivative is rather stable in solution, the aluminum analogue decomposes rapidly. In the solid state, continuous cationic columns running throughout the whole crystal are formed from alternating Li?[M]4 (M = Al, Ga) meso-metallaporphyrin and [Li(THF)4]+ cations. Density functional theory calculations determined that the weak Cl···H, H···H, N···H, and Cl···O interactions with a total interaction energy of ?38.6 kcal·mol?1 are responsible for this unusual packing.
关键词： aluminum,self-assembly,polymerization,meso-metallaporphyrin,gallium,ε-caprolactone
更新于2025-09-04 15:30:14
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Hole-induced polymerized interfacial film of polythiophene as co-sensitizer and back-electron injection barrier layer in dye-sensitized TiO2 nanotube array
摘要： In this work, we demonstrate that an ultra-thin film of polythiophene deposited interfacially via hole-induced polymerization on the surface of dye-sensitized TiO2 nanotube array acts as co-sensitizer, and hinders back-electron transfer in a DSSC. Consequently, the dark current, and the recombination reactions can be suppressed, leading to an improved number of electron density at the TiO2 array electrode. Thus, an enhanced photocurrent, and power conversion efficiency of the device is achieved. This logical concept is experimentally justified, and the device, after polythiophene interfacial treatment, demonstrates an enhanced power conversion efficiency by the factor of 39.19%.
关键词： Interfacial treatment,Back-electron injection barrier,Hole-induced polymerization,TiO2 nanotubes,Polythiophene co-sensitizer,DSSC
更新于2025-09-04 15:30:14
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Desenvolvimento de um obturador de feixe óptico utilizando um disco rígido de computador
摘要： This work demonstrates the development of an optical shutter from a computer hard disk. The electrical current control of the device is made by pulse width modulation, a technique that allows varying current/voltage levels by adjusting the pulse width of a digital signal. This control is made in order to minimize the power dissipated into the device, thus raising its lifetime. The main unit of the control circuit is Arduino Uno, a low cost and ease of programming microcontroller board, extensively used as a platform for electronic prototyping. As an example, we present the use of an optical shutter developed in a microfabrication setup via two-photon polymerization, in which it plays an important role.
关键词： Optical shutter,Arduino Uno,pulse width modulation,two-photon polymerization
更新于2025-09-04 15:30:14
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Dithienobenzimidazole‐containing conjugated donor–acceptor polymers: Synthesis and characterization
摘要： The synthesis of two new conjugated polymers based on the relatively under-exploited monomer, 5,8-dibromo-2-[5-(2-hexyldecyl)-2-thienyl]-1H-dithieno[3,2-e:20,30-g]benzimidazole (dithienobenzimidazole, DTBI), and either 4,7-bis[4-hexyl-5-(trimethylstannyl)-2-thienyl]-2,1,3-benzothiadiazole (BTD) or 2,6-bis(trimethylstannyl)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophene (BDT) is described. The polymers were synthesized via Stille polycondensation and characterized by traditional methods (1H NMR, gel-permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, thermal gravimetric analysis, differential scanning calorimetry, ultraviolet–visible spectroscopy, photoluminescence, and cyclic voltammetry). Prior to their synthesis, trimer structures were modeled by DFT calculations facilitating a further understanding of the systems’ electronic and geometric structure. Polymers were titrated with acid and base to take advantage of their amphiprotic imidazole moiety and their optical response monitored with ultraviolet–visible spectroscopy. Finally, pristine polymer thin-films were treated with acid and base to evaluate (de)protonation’s effect on system electronics, but thin-film degradation was encountered.
关键词： addition polymerization,synthesis,conjugated,conducting polymers,semiconducting polymer,dithienobenzimidazole,ionomers,donor–acceptor
更新于2025-09-04 15:30:14
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Synthesis and characterization of heterocyclic conjugated polymers containing planar Benzo[c]cinnoline and tetraazapyrene structures for organic field-effect transistor application
摘要： Heterocyclic conjugated polymers BZCTVT and TAPTVT containing tetraazapyrene (TAP) and benzo[c]cinnoline (BZC), respectively, were prepared by using Stille coupling polymerization in microwave reactor. TAP and BZC act as acceptors and thiophene-vinylene-thiophene (TVT) acts as donors. Alkylated thiophene is the linker between acceptor and donor. This is the first time that tetraazapyrene was incorporated into conjugated polymers. The films of BZCTVT and TAPTVT showed maximum absorption wavelength at 522 and 534 nm, respectively. From cyclic voltammertry measurement, TAPTVT and BZCTVT exhibited low LUMO (-3.61 and -3.47 eV) and HOMO (-5.64 and -5.63 eV) energy levels. Even though BZC and TAP were planar structures, BZCTVT and TAPTVT showed large dihedral angles between alkylated thiophene and TVT (10.8-22.6o), and between alkylated thiophene and BZC and TAP (22.2-30.3o) based on their simulated energy-minimized geometry. The bottom-gate, top-contact OFETs based on TAPTVT and BZCTVT exhibited only p-channel behavior with hole mobility of 4.63 × 10-4 and 1.04 × 10-4 cm2 V-1 s-1 and current on/off ratios greater than 104 after thermal annealing. Grazing incidence X-ray diffraction (GIXRD) patterns suggested that thin films of TAPTVT and BZCTVT preferred edge-on orientation.
关键词： heterocyclic conjugated polymers,organic field-effect transistor,tetraazapyrene,Stille coupling polymerization,benzo[c]cinnoline
更新于2025-09-04 15:30:14
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Three-Dimensional Photonic Structures Fabricated by Two-Photon Polymerization for Microfluidics and Microneedles
摘要： Polymer micro- and nanostructures with various geometries, such as lines, gratings, woodpiles or dots, can be written onto a transparent substrate by the technique of two-photon polymerization, i.e. focusing a femtosecond laser into a liquid acrylate based resin containing a photo-initiator. The microstructures can be also employed to mimic features found in nature for controlled wetting or liquid transport. Similar structures can be implemented into channels of microfluidic devices to control the transport of fluids herein. In preliminary experiments, we were able to produce microneedles ornamented with microstructures which would facilitate the transport of an aqueous liquid to the needle tip.
关键词： two-photon polymerization,directed fluid transport,microneedles,microfluidics,photonic structures
更新于2025-09-04 15:30:14
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Facile Synthesis of Luminescent CdSeS/Polystyrene Composite Microspheres by Use of Butan-1-ol
摘要： Quantum dot/polymer composites combine the desirable optical properties of quantum dots with the surface properties of colloidal polymer microspheres. The use of the medium polarity solvent, butan-1-ol, facilitates dispersion polymerization of 0.7 μm carboxylated polystyrene/CdSeS composites–the first example of polymer composites with ternary alloyed quantum dots synthesized by dispersion polymerization.
关键词： Polystyrene,Quantum Dot,Dispersion Polymerization,Composite
更新于2025-09-04 15:30:14
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Guiding the Design of Organic Photocatalyst for PET-RAFT Polymerization: Halogenated Xanthene Dyes
摘要： By examining structurally similar halogenated xanthene dyes, this study establishes a guiding principle for resolving structure?property?performance relationships in the photocontrolled PET-RAFT polymerization system (PET-RAFT: photoinduced electron/energy transfer?reversible addition?fragmentation chain transfer). We investigated the effect of the halogen substituents on the photophysical and electrochemical properties of the xanthene dyes acting as photocatalysts and their resultant effect on the performance of PET-RAFT polymerization. Consideration of the structure?property?performance relationships allowed design of a new xanthene photocatalyst, where its photocatalytic activity (oxygen tolerance and polymerization rate) was successfully optimized for PET-RAFT polymerization. We expect that this study will serve as a theoretical framework in broadly guiding the design of high performance photocatalysts for organic photocatalysis.
关键词： PET-RAFT polymerization,structure?property?performance relationships,oxygen tolerance,photocatalysts,halogenated xanthene dyes
更新于2025-09-04 15:30:14
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<i>In My Element</i> : Yttrium
摘要： After a near 7-year pathway devoted solely to late transition metal systems, my hunt in the world of catalysis drove me progressively towards the very left side of the periodic table. Group 4, then group 3, and now group 2 elements. Rare-earths and alkali-earths are really unique elements. Even though going down those two columns and running through the lanthanide row, physicochemical properties most often vary monotonously, their reactivity remains sometimes quite mysterious: who has ever truly rationalized the “peak activity” of neodymium catalyst systems in diene and ethylene polymerization?! But my favorite element isn’t neodymium: its paramagnetism makes for too nasty an NMR spectra to satisfy a molecular chemist in the search for understanding what’s going on in the coordination sphere… No, my special one is yttrium. This one is diamagnetic, providing beautiful, informative NMR spectra. And, importantly for the single-site polymerization catalysis community, some complexes of this abundant element have proved really unique in the ring-opening polymerization of cyclic esters, featuring high activity and unequaled stereocontrol abilities—not unrelated to its small size, which makes for a crowded, discriminative coordination sphere.
关键词： rare-earths,polymerization,alkali-earths,yttrium,catalysis
更新于2025-09-04 15:30:14
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Efficient synthesis of high solid content emulsions of AIE polymeric nanoparticles with tunable brightness and surface functionalization through miniemulsion polymerization
摘要： Efficient production and flexible surface functionalization are important developing directions for the synthesis of polymeric nanomaterials. In this work, aggregation-induced emission (AIE) polymeric nanoparticles (PNPs) were efficiently synthesized by encapsulating a model AIE luminogen, tetraphenylethylene (TPE), within a polymeric matrix via miniemulsion polymerization. The AIE PNPs with similar emission and particle properties were synthesized in a wide solid content range of 8–40 wt%. The particle size and photoluminescence intensity of AIE PNPs could be flexibly tuned by synthetic parameters including the surfactant content and TPE content. Furthermore, the surface carboxyl- and amino-functionalization of AIE PNPs were conveniently achieved through copolymerization of styrene and functional monomers methacrylic acid and 2-aminoethyl methacrylate hydrochloride, respectively, in miniemulsions. The surface functionalization extent could be facilely tuned by the content of functional monomers. This miniemulsion polymerization based technique could be a feasible and efficient method to prepare AIE PNPs with versatile surface functionalization, tunable brightness, and controllable particle properties for the applications in biodetection, bioimaging, etc.
关键词： high solid content,miniemulsion polymerization,Aggregation-induced emission,AIE polymeric nanoparticles,surface functionalization
更新于2025-09-04 15:30:14