Highly Electron-Deficient Hexaazapentacenes and Their Dihydro Precursors

Novel silylethynylated <i>N</i>-heteropentacenes that have three adjacent pyrazine rings at the center of a pentacene backbone are reported. These hexaazapentacenes exhibit a record low energy level of lowest unoccupied molecular orbital (LUMO) for <i>N</i>-heteropentacenes and thus are able to oxidize dihydroanthracene to anthracene. Their synthetic precursors are the corresponding dihydrohexaazapentacenes, which exhibit interesting H-bonding

Table1_The role of smart polymeric biomaterials in bone regeneration: a review.DOCX

Addressing critical bone defects necessitates innovative solutions beyond traditional methods, which are constrained by issues such as immune rejection and donor scarcity. Smart polymeric biomaterials that respond to external stimuli have emerged as a promising alternative, fostering endogenous bone regeneration. Light-responsive polymers, employed in 3D-printed scaffolds and photothermal therapies, enhance antibacterial efficiency and bone repair. Thermo-responsive biomaterials show promise in controlled bioactive agent release, stimulating osteocyte differentiation and bone regeneration. Further, the integration of conductive elements into polymers improves electrical signal transmission, influencing cellular behavior positively. Innovations include advanced 3D-printed poly (l-lactic acid) scaffolds, polyurethane foam scaffolds promoting cell differentiation, and responsive polymeric biomaterials for osteogenic and antibacterial drug delivery. Other developments focus on enzyme-responsive and redox-responsive polymers, which offer potential for bone regeneration and combat infection. Biomaterials responsive to mechanical, magnetic, and acoustic stimuli also show potential in bone regeneration, including mechanically-responsive polymers, magnetic-responsive biomaterials with superparamagnetic iron oxide nanoparticles, and acoustic-responsive biomaterials. In conclusion, smart biopolymers are reshaping scaffold design and bone regeneration strategies. However, understanding their advantages and limitations is vital, indicating the need for continued exploratory research.</p

Hydrogen-Bonded Dihydrotetraazapentacenes

Three new members of <i>N</i>-heteropentacenes explored herein have adjacent pyrazine and dihydropyrazine rings at one end of the pentacene backbone. Interesting findings from this study include self-complementary N–H···N H-bonds in the solid state, solvent-dependent UV–vis absorption caused by H-bonding, and new <i>p</i>-type organic semiconductors with field effect mobility up to 0.7 cm² V^–1 s^–1

Hydrogen-Bonded Dihydrotetraazapentacenes

Three new members of <i>N</i>-heteropentacenes explored herein have adjacent pyrazine and dihydropyrazine rings at one end of the pentacene backbone. Interesting findings from this study include self-complementary N–H···N H-bonds in the solid state, solvent-dependent UV–vis absorption caused by H-bonding, and new <i>p</i>-type organic semiconductors with field effect mobility up to 0.7 cm² V^–1 s^–1

Reconfiguring Nanocomposite Liquid Crystal Polymer Films with Visible Light

Patterns of white light are projected on liquid crystal (LC) polymer films containing gold nanospheres (NS) or nanorods (NR) to induce out-of-plane buckling through a photothermal effect. Straightforward synthetic techniques are used to provide well-dispersed nanocomposite films, with NRs exhibiting self-alignment with the LC director. Using a combination of prepatterned director orientation and spatiotemporal variations in light intensity, these nanocomposite films can be reversibly configured into different 3D states. Fine control over shape is demonstrated through variations in size, shape, and intensity of the illuminated region. Switching time scales are found to be of order a few seconds or below, likely reflecting the intrinsic relaxation time of the LC materials

High-Quality Large-Area Graphene from Dehydrogenated Polycyclic Aromatic Hydrocarbons

Recent studies show that, at the initial stage of chemical vapor deposition (CVD) of graphene, the isolated carbon monomers will form defective carbon clusters with pentagons that degrade the quality of synthesized graphene. To circumvent this problem, we demonstrate that high-quality centimeter-sized graphene sheets can be synthesized on Cu foils by a self-assembled approach from defect-free polycyclic aromatic hydrocarbons (PAHs) in a high vacuum (HV) chamber without hydrogen. Different molecular motifs, namely coronene, pentacene, and rubrene, can lead to significant difference in the quality of resulting graphene. For coronene, monolayer graphene flakes with an adequate quality can be achieved at a growth temperature as low as 550 °C. For the graphene obtained at 1000 °C, transport measurements performed on back-gated field-effect transistors (FETs) with large channel lengths (∼30 μm) exhibit a carrier mobility up to ∼5300 cm² V^–1 s^–1at room temperature. The underlying growth mechanism, which mainly involves surface-mediated nucleation process of dehydrogenated PAHs rather than segregation or precipitation process of small carbon species decomposed from the precursors, has been systematically investigated through the first-principles calculations. Our findings pave the way for optimizing selection of solid carbon precursors and open up a new route for graphene synthesis

CdTe Quantum Dots Encapsulated ZnO Nanorods for Highly Efficient Photoelectrochemical Degradation of Phenols

Vertically aligned CdTe–ZnO composite nanorods are constructed on the indium tin oxide substrates by layer-by-layer deposition of CdTe quantum dots on ZnO nanorod arrays. The CdTe shell forms an intact interface with the wurtzite ZnO nanorod, and its thickness can be accurately tuned by changing the deposition cycles. Photoluminescent measurements further disclose the band alignment between the CdTe shell and the ZnO core, which makes CdTe–ZnO composite nanorods exhibiting good photoelectron-chemical properties and being a prospective material for removal of phenol from wastewater under visible light irradiation. Impressively, about 75% degradation of 100 mg/L phenol solution and up to 53.2% removal of the total organic carbon are achieved within 150 min using the optimized CdTe–ZnO composite nanorods as photoelectrocatalysts under visible light

Massively Parallel Patterning of Complex 2D and 3D Functional Polymer Brushes by Polymer Pen Lithography

We report the first demonstration of centimeter-area serial patterning of complex 2D and 3D functional polymer brushes by high-throughput polymer pen lithography. Arbitrary 2D and 3D structures of poly­(glycidyl methacrylate) (PGMA) brushes are fabricated over areas as large as 2 cm × 1 cm, with a remarkable throughput being 3 orders of magnitudes higher than the state-of-the-arts. Patterned PGMA brushes are further employed as resist for fabricating Au micro/nanostructures and hard molds for the subsequent replica molding of soft stamps. On the other hand, these 2D and 3D PGMA brushes are also utilized as robust and versatile platforms for the immobilization of bioactive molecules to form 2D and 3D patterned DNA oligonucleotide and protein chips. Therefore, this low-cost, yet high-throughput “bench-top” serial fabrication method can be readily applied to a wide range of fields including micro/nanofabrication, optics and electronics, smart surfaces, and biorelated studies

Enhanced Performance and Fermi-Level Estimation of Coronene-Derived Graphene Transistors on Self-Assembled Monolayer Modified Substrates in Large Areas

The performance of graphene field effect transistors (GFETs) strongly depends on the interface between graphene sheets and the underlying substrates. In this work, we report that an octadecyltrimethoxysilane (OTMS) SAM modified conventional SiO₂/Si substrate can consistently enhance the performance of coronene-derived large-area graphene FETs. The improved transport properties in terms of boosted carrier mobility (up to 10 700 ± 300 cm² V^–1 s^–1), long mean free path, nearly vanished hysteretic behavior, and remarkably low intrinsic doping level are mainly attributed to the strong suppression of interfacial charge impurity scattering and remote interfacial phonon (RIP) scattering, less adsorption of dipolar adsorbates, and the attenuated charger transfer at the interface of graphene and dielectric. The intrinsic doping levels (the Fermi energy) of graphene on OTMS-modified and bare SiO₂ have been quantitatively estimated and confirmed by the Dirac points of GFETs, the Raman mapping of <i>G</i>-peak positions, and the surface potential maps by KPFM. The facile fabrication of a graphene device over a large area provides an unprecedented combination of high performance and low cost for the future application of all carbon-based nanoelectronics

Enhanced Near-Infrared to Visible Upconversion Nanoparticles of Ho³⁺-Yb³⁺-F^– Tri-Doped TiO₂ and Its Application in Dye-Sensitized Solar Cells with 37% Improvement in Power Conversion Efficiency

New near-infrared (NIR)-to-green upconversion nanoparticles of Ho³⁺-Yb³⁺-F^– tridoped TiO₂ (UC-F-TiO₂) were designed and fabricated via the hydrosol–hydrothermal method. Under 980 nm NIR excitation, UC-F-TiO₂ emit strong green upconversion fluorescence with three emission bands at 543, 644, and 751 nm and convert the NIR light <i>in situ</i> to the dye-sensitive visible light that could effectively reduce the distance between upconversion materials and sensitizers; thus, they minimize the loss of the converted light. Our results show that this UC-F-TiO₂ offers excellent opportunities for the other types of solar cells applications, such as organic solar cells, c-Si solar cells, multijunction solar cells, and so on. When integrating the UC-F-TiO₂ into dye-sensitized solar cells (DSSCs), superior total energy conversion efficiency was achieved. Under AM1.5G light, open-circuit voltage reached 0.77 ± 0.01 V, short-circuit current density reached 21.00 ± 0.69 mA cm^–2, which resulted in an impressive overall energy conversion efficiency of 9.91 ± 0.30%, a 37% enhancement compared to DSSCs with pristine TiO₂ photoanode