Energy levels and energy level alignment at interfaces play a decisive role in designing efficient and stable organic solar cells (OSCs). In this review two usually used technologies in organic photovoltaic communities for measuring energy levels of organic semiconductors, photoelectron spectroscopy and electrochemical methods, are introduced, and the relationships between the values obtained from the corresponding techniques are compared. The energy level and energy level alignment across the interfaces involved in solution processed organic photovoltaics are described, and the corresponding integer charge transfer model for predicting and explaining energy level alignment are presented. The effects of the interface properties in designing efficient binary and ternary OSCs were discussed. The effects of environmental factors mainly including water vapor, oxygen gas and thermal annealing on energy levels and energy level alignment involved in photoactive layers, and the subsequent effects on the corresponding OSC properties are given.
We developed a novel Pd-catalyzed [4 + 4] cycloaddition of benzofuran-derived azadienes with homo-TMM all-carbon 1,4-dipoles in situ generated from α-allyl malonate derivatives, affording an array of benzofuro[3,2-b]azocines with good to excellent yields (up to 96%) and exclusive regioselectivities. This methodology featured mild reaction conditions and good functional group tolerance. The synthetic utility was demonstrated by a gram-scale reaction. Furthermore, the catalytic asymmetric [4 + 4] cycloaddition version has also been explored.
Hydrogen bonding is a vital driving force for organizing the hierarchy molecular structure, especially in biologic field. Due to its directionality, selectivity and moderate strength, hydrogen bonding has been extensively introduced into the molecular recognition, sensing and electronic devices. Electric meas-urements at single-molecule level facilitate the investigation of hydrogen bonds and provide a comprehensive understanding of the electron transport properties governed by the hydrogen bonding, which is essential for the development of self-assembled electronic systems. This review provides a de-tailed overview of recent advancements in constructing single-molecule junctions utilizing intramolecular and intermolecular hydrogen bonding. We first introduce the methods utilized for characterizing the electric and dynamic properties of non-covalent interactions. Next, we discuss the mechanisms of electron transport, relevant influencing factors, and typical applications utilizing electrical signals based on single-molecule junctions. Finally, we propose our perspective on the existing challenges and prospective opportunities in utilizing hydrogen bonding for electronic device applications.
C-aryl glycosides are an important kind of carbohydrate derivatives for drug discovery, due to their distinctive attributes of resistance to hydrolysis from enzymes. Herein, C-aryl glycosylation was established for the synthesis of 2-sulfur C-aryl glycals and 1,2-dihydrobenzofuran-fused C-aryl glycosides via interrupted Pummerer process, featured with sulfonium-tethered [3,3]-sigmatropic rearrangement between sulfoxide glycals and phenols. This protocol offers a broad substrate scope with diverse glycosyl and phe-nols. Dapagliflozin, Empagliflozin, and Ipragliflozin analogs were straightforward achieved, respectively.
Narrow-bandgap n-type polymers are essential for advancing the development of all-polymer solar cells (all-PSCs). Herein, we developed a novel polymer acceptor PNT with π-extended 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene) malononitrile (CPNM) end groups. Compared to commonly used 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1ylidene) malononitrile (IC) units, CPNM units have a further extended fused ring, providing the PNT polymer with extended absorption into the near-IR region (903 nm) and exhibiting a narrow optical bandgap (1.37 eV). Furthermore, PNT exhibits high electron mobility (6.79 × 10−4 cm2 V−1 S−1) and a relatively high-lying lowest unoccupied molecular orbital (LUMO) energy level of −3.80 eV. When blended with PBDB-T, all-PSC achieves a power conversion efficiency (PCE) of 13.7% and a high short-circuit current density (JSC) of 24.4 mA cm−2, mainly attributed to broad absorption (600-900 nm) and efficient charge separation and collection. Our study provides a promising polymer acceptor for all-PSCs and demonstrates that π-extended CPNM units are important to achieve high-performance for all-PSCs.
The kinetic process of a slow oxygen evolution reaction (OER) always constrains the efficiency of overall water electrolysis for H2 production. In particular, nonprecious metal electrodes for the OER have difficulty simultaneously possessing good electrocatalytic activity and long-term stability in pH-universal media. In this work, urea is first used as a pore-forming agent and active C/N source to fabricate a nanoporous NiFeCoCN medium-entropy alloy (MEA) by high-temperature sintering based on the nanoscale Kirkendall effect. The NiFeCoCN MEA achieves an overpotential of 432 mV at a current density of 10 mA cm-2 and a lower Tafel slope of 52.4 mV dec-1 compared to the IrO2/Ti electrode (58.6 mV dec-1) in a 0.5 M H2SO4 solution. In a 1 M KOH solution, the NiFeCoCN MEA obtains an overpotential of 177 mV for 10 mA cm-2 and a Tafel slope of 36.1 mV dec-1, which is better than IrO2/Ni foam. This work proves a novel strategy to design and prepare nanoporous MEA materials with desirable C/N species, which provides promising prospects for the industrial production of H2 energy.
A transition-metal free three-component coupling reaction of azaindoles, C60, and bromoalkanes/triphenylamines has been developed to provide an efficient access to diverse azaindole functionalized 1,4-C60 adducts. This protocol exhibits low cost, operational-simplicity, wide substrate scope, and mild and convenient conditions.
One-dimensional semiconductor-metal heterostructures manifest improved charge separation capability, tunable band gap and increased surface area, and have been regarded as promising photocatalysts for solar-to-fuel conversion through water splitting. We herein review the synthetic strategies for the rational design and preparation of one-dimensional semiconductor-metal heterostructures with precise control in terms of size, shape, composition and function. Approaches that are capable of improving the photocatalytic performance of one-dimensional semiconductor-metal heterostructures have been proposed and analyzed The present work is expected to give the rational design of one-dimensional semiconductor-metal heterostructures and provide insights into accomplishing highly efficient photocatalysis based on such materials
Fuel-driven dissipative self-assembly, which is a well-established concept in recent years, refers to out-of-equilibrium molecular self-assembly initiated and supported by the addition of active molecules (chemical fuel). It widely exists in nature since many tempo-rary, active micro- or nanostructures in living bodies are generated by the dissipative self-assembly of biomolecules. Therefore, the study on dissipative self-assembly provides a good opportunity to have an insight into the microscopic mechanism of living organisms. In the meantime, dissipative assembly is thought to be a potential pathway to achieve dynamic, temporary supramolecular materials. Recently, a number of temporary materials have been developed with the aid of strategies for realizing dissipative self-assembly. Some of their properties, including solubility, stiffness, turbidity, color, or self-healing ability, change upon the addition of chemical fuel but spontaneously restore with chemical fuel consumption. The dynamic of these materials brings them various unprecedented functions. In this review, the principles of fabricating a fuel-driven temporary material are first reviewed and subsequently, recent examples of fuel-driven temporary materials are emphatically summarized, including gels, self-erased inks, nanoreactors, self-healing materials, and nanochannels. Finally, the challenges of developing fuel-driven temporary materials and some perspectives on the function and application of such kind of materials are discussed.
Besides serving as therapeutic agents and building blocks for glycoprotein synthesis, homogeneous synthetic glycopeptides also benefit understanding function of specific glycoform. However, the selectivity coupling of oligosaccharides to a given peptide remains challenging despite the fact that the synthesis of structure-defined complex oligosaccharides has been greatly facilitated by chemoenzymatic based approaches. Herein, a Ca2+-promoted glycosylation approach was developed to exclusively modify phenolic peptide using a panel of biologically important glycans.
This review presents a comprehensive examination of fully conjugated covalent organic frameworks (COFs), which constitute an emerging class of porous materials with immense potential for diverse applications. This article focuses on diversified fully conju-gated COFs, including sp2 carbon-carbon linkages, pyrazine linkages, benzobisoxazole linkages, dioxin linkages, β-aminoalkenone linkages, etc. The synthesis techniques and structural attributes of these COFs are expounded upon in great detail, along with their potential applications in various fields. The review thus provides a valuable resource for researchers keen on delving into the synthe-sis and applications of fully conjugated COFs, thereby highlighting their potential for developing novel functional materials with dis-tinctive properties.
A photo-triggered cascade cyclization of silyl enolate to prepare angularly fused tricyclic scaffold is developed. The reaction demonstrates good substrate scope and stereo-selectivity. The excellent stereo- and regio-selectivity for this cascade reaction is elucidated via conformational analysis and DFT calculation, respectively.
A transition-metal-free one-pot direct synthesis of tetrathiophosphates (R1S)2P(S)SR2 from white phosphorus (P4), through inter-mediate S-sodium S,S-dialkylphosphorotetrathioates (R1S)2P(S)SNa, is presented. In the presence of NaSH, various disulfides such as diaryl disulfides and dialkyl disulfides are easily coupled with P4 to give S-sodium S,S-dialkylphosphorotetrathioates (R1S)2P(S)SNa in almost quantitative yield, which react with alkyl halides in one pot to generate (R1S)2P(S)SR2. Furthermore, S-(2-cyanoethyl)-substituted tetrathiophosphates (R1S)2P(S)SCH2CH2CN are successfully designed as a kind of tetrathiophosphorylation reagents to react with diaryl iodonium salts involving deprotection-dealkylation process.
Nickel(II) complexes with pyrazole-based ligands are widely employed in catalysis of ethylene oligomerization and subsequent Friedel-Crafts alkylation of toluene. We have prepared ten new nickel(II) dibromide complexes with various substituted bis(azolyl)methanes. They have been characterized using 1H NMR, IR, high resolution mass spectrometry and elemental analysis. The structures of three complexes have been unambiguously established using X-ray diffraction. It was found that these complexes in the presence of Et2AlCl or Et3Al2Cl3 are active both in ethylene oligomerization and Friedel-Crafts alkylation processes (activity up to 3720 kgoligomer·mol[Ni]−1·h−1). The use of Et3Al2Cl3 results in the higher share of alkylated products (up to 60%). Moreover, catalytic systems activated with Et3Al2Cl3 produced small amounts of odd carbon number olefins (up to 0.8%). The Friedel-Crafts alkylation was used as a trap for previously undetected short-chain odd carbon number olefins (C3 and C5).
A new electrophilic monofluoromethylthiolating reagent N-fluoromethylthiophthalimide PhthSCH2F 1 was developed. Reagent 1 could be readily synthesized from easily available starting materials benzyl mercaptan and CH2FCl in three steps. N-fluoromethylthiophthalimide 1 is a powerful electrophilic monofluoromethylthiolating reagent that allows the monofluorome-thylthiolation of a wide range of nucleophiles including alkynes, aryl/vinyl boronic acids, electron-rich heteroarenes,-ketoesters and oxindoles, as well as thiols under mild conditions.
Traditional molecular biology tools have elucidated the identities and functions of RNA molecules, which are essential to the understanding of gene transcription and protein translation. Deepening this research field would further require the direct visualization of RNA dynamics such as the DNA-RNA interactions and RNA-protein interactions. Towards this goal, the rise of RNA imaging tools over the past 15 years has reformed how we looked at these processes. In this emerging topic, we first highlighted recent advances on three main RNA imaging tools based on the species of interacting molecules: RNA-RNA pairing, RNA-protein binding, and small molecule-RNA complex. We introduced the advantages of these tools from a technical viewpoint, including binding affinity, fluorescent turn-on ratio, stability, and impacts on targeted RNA. Next, we discussed new rising opportunities and future directions, echoing the state-of-the-art imaging tools in the fields of fluorescent proteins and small fluorescent molecules. Together, we believe this emerging field will bring new insights on how we study RNA biology in living systems.
We herein report a simple ether-directed iridium-catalyzed site- and enantioselective C(sp2)-H borylation of benzhydryl ethers for the first time. Various chiral benzhydryl ethers were obtained with high enantioselectivities in the presence of a tailor-made chiral bi-dentate boryl ligand. We found that the kinetic resolution relay significantly amplified the enantioselectivity. The synthetic utility of the current method was demonstrated by gram-scale C-H borylation and C-B bond transformations.
Ultra-narrow bandgap (ultra-NBG) small molecule acceptors (SMAs) show great potential in organic solar cells (OSCs) due to the extend-ed near-infrared (NIR) absorption. In this work, a synergetic alkoxy side-chain and chlorine-contained end group strategy is employed to achieve A-DA’D-A type ultra-NBG SMAs by introducing alkoxy chains with oxygen atom at the second position into the thiophene β posi-tion as well as replacing the F atoms with Cl atoms in the end group. As a result, the heptacyclic BZO-4F shows a redshifted absorption onset (960 nm) than Y11 (932 nm) without oxygen atoms in the side chains. Then, the fluorinated end groups are substituted with the chlorinated ones to synthesize BZO-4Cl. The absorption onset of BZO-4Cl is further redshifted to 990 nm, corresponding to an optical ultra-NBG of 1.25 eV. When blending with the polymer donor PBDB-T, the binary devices based on PBDB-T: BZO-4F and PBDB-T: BZO-4Cl delivers power conversion efficiencies (PCEs) over 12%. Furthermore, ternary devices with the addition of BZ4F-O-1 into PBDB-T: BZO-4Cl system achieve the optimal PCE of 15.51%. This work proposes a synergetic alkoxy side-chain and chlorine-contained end group strategy to achieve A-DA’D-A type ultra-NBG SMAs, which is important for future molecular design.