Rational design of noble metal catalysts with the potential to leverage efficiency is vital for industrial applications. Such an ultimate atom-utilization efficiency can be achieved when all noble metal atoms exclusively contribute to catalysis. Here, we demonstrate the fabrication of wafer-size amorphous PtSex film on SiO2 substate via a low-temperature amorphizing strategy, which offers single-atom-layer Pt catalysts with high atom-utilization efficiency (~26 wt%). This amorphous PtSex (1.2

Narrow bandgap (1.37-1.46 eV) polymers incorporating a head-to-head linkage containing 3-alkoxy-3'-alkyl-2,2'-bithiophene are synthesized. The head-to-head linkage enables polymers with sufficient solubility and the noncovalent sulfur-oxygen interaction affords polymers with high degree of backbone planarity and film ordering. When integrated into polymer solar cells, the polymers show a promising power conversion efficiency approaching 10%.

Imide-functionalized arenes, exemplified by naphthalene diimides (NDIs), perylene diimides (PDIs), and bithiophene imides (BTIs), are the most promising building blocks for constructing high-performance n-type polymers. In order to reduce the steric hindrance associated with NDI- and PDI-based polymers and to address the high-lying LUMO issue of BTI-based polymers, herein a highly electron-deficient imide-functionalized bithiazole, N-alkyl-5,5′-bithiazole-4,4′-dicarboximide (BTzI), was successfully synthesized via an efficient C–H activation. Single crystal of BTzI model compound showed a planar backbone with close π-stacking distances (3.2–3.3 Å). The N,N′-bis­(2-alkyl)-2,2′-bithiazolethienyl-4,4′,10,10′-tetracarboxdiimide (DTzTI) was also used for constructing polymer semiconductors. Compared to DTzTI, BTzI is more electron-deficient, rendering it highly appealing for enabling n-type polymers. On the basis of BTzI and DTzTI, a series of polymers, including acceptor–acceptor homopolymers, and donor–acceptor and donor–acceptor–acceptor copolymers, were synthesized, which feature different contents of acceptor units in polymeric backbones. As imide content increases, the polymer FMO levels were gradually lowered, yielding a transition of charge carrier from ambipolarity to unipolar n-type in organic thin-film transistors (OTFTs). The acceptor–acceptor homopolymer PBTzI possesses the deepest LUMO/HOMO level of −3.94/-6.17 eV, enabling minimal off-current (I off) of 10–10–10–11 A in OTFTs. The highest electron mobility of 1.61 cm2 V–1 s–1 accompanied by small I off of 10–10–10–11 A and high on-current/off-current ratio (I on/I off) of 107–108 was achieved from OTFTs using PDTzTI homopolymer, showing the pronounced advantages of acceptor-acceptor homopolymer approach for developing unipolar n-type polymer semiconductors. The correlations between the FMO levels and the transistor performances underscore the significance of FMO tuning for enabling unipolar electron transport. The results demonstrate that imide-functionalized thiazoles are excellent units for constructing high-performance n-type polymers. Moreover, the synthetic routes to these highly electron-deficient imide-functionalized thiazoles and the polymer structure–property correlations developed here are informative for materials invention in organic electronics.

ABSTRACT:The photoelectron spectrum of the oxyallyl (OXA) radical anion has been measured. The radical anion has been generated in the reaction of the atomic oxygen radical anion (O •-) with acetone. Three low-lying electronic states of OXA have been observed in the spectrum. Electronic structure calculations have been performed for the triplet states ( 3 B 2 and 3 B 1 ) of OXA and the ground doublet state ( 2 A 2 ) of the radical anion using density functional theory (DFT). Spectral simulations have been carried out for the triplet states based on the results of the DFT calculations. The simulation identifies a vibrational progression of the CCC bending mode of the 3 B 2 state of OXA in the lower electron binding energy (eBE) portion of the spectrum. On top of the 3 B 2 feature, however, the experimental spectrum exhibits additional photoelectron peaks whose angular distribution is distinct from that for the vibronic peaks of the 3 B 2 state. Complete active space selfconsistent field (CASSCF) method and second-order perturbation theory based on the CASSCF wave function (CASPT2) have been employed to study the lowest singlet state ( 1 A 1 ) of OXA. The simulation based on the results of these electronic structure calculations establishes that the overlapping peaks represent the vibrational ground level of the 1 A 1 state and its vibrational progression of the CO stretching mode. The 1 A 1 state is the lowest electronic state of OXA, and the electron affinity (EA) of OXA is 1.940 ( 0.010 eV. The 3 B 2 state is the first excited state with an electronic term energy of 55 ( 2 meV. The widths of the vibronic peaks of theX 1 A 1 state are much broader than those of theã 3 B 2 state, implying that the 1 A 1 state is indeed a transition state. The CASSCF and CASPT2 calculations suggest that the 1 A 1 state is at a potential maximum along the nuclear coordinate representing disrotatory motion of the two methylene groups, which leads to three-membered-ring formation, i.e., cyclopropanone. The simulation ofb 3 B 1 OXA reproduces the higher eBE portion of the spectrum very well. The term energy of the 3 B 1 state is 0.883 ( 0.012 eV. Photoelectron spectroscopic measurements have also been conducted for the other ion products of the O •-reaction with acetone. The photoelectron imaging spectrum of the acetylcarbene (AC) radical anion exhibits a broad, structureless feature, which is assigned to theX 3 A 00 state of AC. The ground ( 2 A 00 ) and first excited ( 2 A 0 ) states of the 1-methylvinoxy (1-MVO) radical have been observed in the photoelectron spectrum of the 1-MVO ion, and their vibronic structure has been analyzed.

has seen limited progress owing to their instability in solution and insufficient activation of reactants by single metal sites under ambient conditions. [4,5] Consequently, applications of SACs in organic synthesis were limited to certain hydrogenations, [6,7] oxidations, [8,9] and CC bond formations. [10] Very recently, we have reported the first SAC-catalyzed preparation of pharmaceuticals (Lonidamine etc., and their 15 N-labeled analogues) by selective hydrogenation to E-hydrazones and subsequent cyclization using Pt 1 /CeO 2 catalyst. [11] We have also developed the latestage functionalization of pharmaceuticals (Tamiflu) by chemoselective oxidation of sulfides using Co 1 -in-MoS 2 catalyst. [12] Despite excellent functional group tolerance and synthetic utility in both cases, the scope is limited by the use of complex starting materials (i.e., carboxylic esters mediated α-diazoesters synthesis and multifunctionalized sulfides), and the inaccessibility to synthesize multi-ring system as the reactions mainly involve simple hydrogenation/oxidation. [11,12] Quinolines, a major class of heterocycles, are widely occurring in natural and synthetic products with diverse pharmacological and physical properties. [13,14] Among the many methods to synthesize quinolines, the classical Friedländer condensation of an aromatic 2-amino-substituted carbonyl compound with another substituted carbonyl derivative is one of the simplest The production of high-value chemicals by single-atom catalysis is an attractive proposition for industry owing to its remarkable selectivity. Successful demonstrations to date are mostly based on gas-phase reactions, and reports on liquid-phase catalysis are relatively sparse owing to the insufficient activation of reactants by single-atom catalysts (SACs), as well as, their instability in solution. Here, mechanically strong, hierarchically porous carbon plates are developed for the immobilization of SACs to enhance catalytic activity and stability. The carbon-based SACs exhibit excellent activity and selectivity (≈68%) for the synthesis of substituted quinolines by a three-component oxidative cyclization, affording a wide assortment of quinolines (23 examples) from anilines and acetophenones feedstock in an efficient, atom-economical manner. Particularly, a Cavosonstat derivative can be synthesized through a one-step, Fe 1 -catalyzed cyclization instead of traditional Suzuki coupling. The strategy is also applicable to the deuteration of quinolines at the fourth position, which is challenging by conventional methods. The synthetic utility of the carbon-based SAC, together with its reusability and scalability, renders it promising for industrial scale catalysis.

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Significant progress has been made in nonfullerene small molecule acceptors (NF‐SMAs) that leads to a consistent increase of power conversion efficiency (PCE) of nonfullerene organic solar cells (NF‐OSCs). To achieve better compatibility with high‐performance NF‐SMAs, the direction of molecular design for donor polymers is toward wide bandgap (WBG), tailored properties, and preferentially ecofriendly processability for device fabrication. Here, a weak acceptor unit, methyl 2,5‐dibromo‐4‐fluorothiophene‐3‐carboxylate (FE‐T), is synthesized and copolymerized with benzo[1,2‐b:4,5‐b′]dithiophene (BDT) to afford a series of nonhalogenated solvent processable WBG polymers P1‐P3 with a distinct side chain on FE‐T. The incorporation of FE‐T leads to polymers with a deep highest occupied molecular orbital (HOMO) level of −5.60−5.70 eV, a complementary absorption to NF‐SMAs, and a planar molecular conformation. When combined with the narrow bandgap acceptor ITIC‐Th, the solar cell based on P1 with the shortest methyl chain on FE‐T achieves a PCE of 11.39% with a large V oc of 1.01 V and a J sc of 17.89 mA cm−2. Moreover, a PCE of 12.11% is attained for ternary cells based on WBG P1, narrow bandgap PTB7‐Th, and acceptor IEICO‐4F. These results demonstrate that the new FE‐T is a highly promising acceptor unit to construct WBG polymers for efficient NF‐OSCs.

The fusion of heteroaromatic rings into ladder-type heteroarenes can stabilize frontier molecular orbitals and lead to improved physicochemical properties that are beneficial for applications in various optoelectronic devices. Thus, ladder-type heteroarenes, which feature highly planar backbones and well-delocalized π conjugation, have recently emerged as a promising type of organic semiconductor with excellent device performance in organic photovoltaics (OPVs) and organic field-effect transistors (OFETs). In this Focus Review, we summarize the recent advances in ladder-type heteroarene-based organic semiconductors, such as hole- and electron-transporting molecular semiconductors, and fully ladder-type conjugated polymers towards their applications in OPVs and OFETs. The recent use of ladder-type small-molecule acceptor materials has strikingly boosted the power conversion efficiency of fullerene-free solar cells, and selected examples of the latest developments in ladder-type fused-ring electron acceptor materials are also elaborated.