Imide- and amide-functionalized polymer semiconductors

Full Conjugation in a Polymer with Non-conjugated Piperazine-2,5-dione Units via Energy-minimized Lactam-to-Lactim Tautomerization Enables Water-gated Transistor Fluoride Sensors

Piperazine-2,5-dione (glycine anhydride, GA) has recently emerged as a valuable precursor for high-performance π-conjugated polymer semiconductors in organic electronics. We utilized GA to design a novel bisindolin-dihydropiperazine (IDHP)-based conjugated polymer, PIDHPTT, for aqueous chemical sensing. In the isatin-flanked monomer, GA exists as a non-conjugated lactam (DHP-NH) but converts to a conjugated lactim (DHP-OH) form within the polymer. Density functional theory (DFT) calculations show that this conversion is driven by energy minimization via extended π-conjugation. Neighboring DHP units in the lactim form facilitate this process through π-bridges, demonstrating a vinylogous effect, which has previously only been observed in small molecules. This is the first study to report such a long-range vinylogous effect in a polymer due to the collective synergy of numerous functional groups. The OH groups in the lactim DHP interact more strongly with fluoride ions than other halides. PIDHPTT exhibits significant changes in optical absorption, electrochemical impedance, and charge transport in response to fluoride ions, which differ from responses to other halides. A water-gated organic field-effect transistor based on PIDHPTT shows excellent sensitivity and selectivity for fluoride ions, demonstrating the potential of this polymer design for chemical sensing applications.

Chemoselective Cleavage and Transamidation of Tertiary p-Methoxybenzyl Amides under Metal-Free Photoredox Catalysis

A metal-free and mild cleavage of tertiary p-methoxybenzyl amides (PMB tert-amide) under photoredox conditions is developed using Mes-Acr-Ph+BF4- and Selectfluor to activate the electron-rich benzylic C-H bond of the PMB moiety. The resulting acyl fluoride intermediate is versatile and facilitates a one-pot transamidation of the PMB tert-amide. The value of this protocol is highlighted by performing the chemoselective activation of the PMB tert-amide in bifunctional molecules containing more reactive functionalities than the amide.

Non-alternant Benzodifluoranthene Tetraimides from 7,8,9,10-Fluoranthene Diimides: Synthesis, Structure, and Optical-Limiting Properties

A novel tetraimide-functionalized non-alternant π-conjugated system, namely, benzodifluoranthene tetraimides (BDFTI), has been designed and synthesized through highly efficient UV-photocyclization of a vinyl-bridged fluoranthene diimide dimer (i. e., FDI-V). The synthesis of FDI-V starts from a straightforward three-step route to produce novel 7,8,9,10-fluoranthene diimide (FDIs) building-blocks, followed by nearly complete bromination and then Stille-coupling reaction to give the desired dimer. The analysis by X-ray crystallography confirms a near-coplanar geometry for FDIs, while BDFTI shows a U-shaped and distorted backbone configuration proven by theoretical optimizations. The tetraimide BDFTI exhibits several advantages over the FDI cores, including an extended absorption band and a red-shift in photoluminescence spectra. This enhancement can be attributed to the presence of additional electron-deficient imide units, which promotes increased intramolecular charge transfer and improved electron affinity. All the imides show a local aromatic characteristic owing to the incorporation of pentagon rings in the π-frameworks. The fully fused BDFTI exhibits nonlinear optical properties as analyzed by the open-aperture Z-scan technique, demonstrating superior optical-limiting performance compared to vinyl-bridged FDI-V. The versatile UV-photocyclization chemistries provide a pathway for developing complex and unique multiimide-functionalized π-conjugated systems, paving the way for creating high-performance optical-limiting materials.

Oxidative Amidation of Ferrocenyl Aldehydes with Amines Catalyzed by Chalcogenised Fe3Se2(CO)9 Cluster: Direct Transformation of Aldehyde to Amides

With the interest and knowing the importance of ferrocenyl conjugates, a direct amidation of ferrocenyl aldehyde has been developed under feasible conditions. Varieties of amines has been oxidatively coupled with ferrocene aldehyde in the presence of highly economical and robustly stable iron chalcogenide ironcarbonyl clusters [Fe3E2(CO)9, E= S, Se, and Te] and TBHP. The reaction worked in greener solvent water at a moderate temperature of 70 °C and the ferrocenyl-amides in just 30 minutes. All the varieties of amines were found to be well tolerated for the present method, and due to the high medicinal importance of ferrocenyl-amides, sole focus of this report was concentrates on the synthesis of various new ferrocenyl-amides in good to excellent amounts.

Fully Fused Indacenodithiophene-Centered Small-Molecule n-Type Semiconductors for High-Performance Organic Electronics

Developing novel n-type organic semiconductors is an on-going research endeavour, given their pivotal roles in organic electronics and their relative scarcity compared to p-type counterparts. In this study, a new strategy was employed to synthesize n-type organic semiconductors featuring a fully fused conjugated backbone. By attaching two sets of adjacent amino and formyl groups to the indacenodithiophene-based central cores and triggering a tandem reaction sequence of a Knoevenagel condensation-intramolecular cyclization, DFA1 and DFA2 were realized. The solution-processed organic field effect transistors based on DFA1 exhibited unipolar n-type transport character with a decent electron mobility of ca. 0.10 cm2 V-1 s-1 (ca. 0.038 cm2 V-1 s-1 for DFA2 based devices). When employing DFA1 as a third component in organic solar cells, a high power conversion efficiency of 19.2 % can be achieved in ternary devices fabricated with PM6 : L8-BO : DFA1. This work provides a new pathway in the molecular engineering of n-type organic semiconductors, propelling relevant research forward.

An n-Doping Cross-Linkable Quinoidal Compound as an Electron Transport Material for Fully Stretchable Inverted Organic Solar Cells

The photocatalytic activity and inherent brittleness of ZnO, which is commonly used as an electron transport layer (ETL) in inverted organic solar cells (OSCs), have impeded advancements in device stability and the development of fully stretchable OSCs. In this study, an intrinsically stretchable ETL for inverted OSCs through a side-chain cross-linking strategy has been developed. Specifically, cross-linking between bromine atoms on the side chains of a quinoidal compound and the amino groups in polyethylenimine resulted in a film, designated QBr-PEI-50, with high electrical conductivity (0.049 S/m) and excellent stretchability (crack-onset strain>45 %). When used as the ETL in inverted OSCs, QBr-PEI-50 was markedly superior to ZnO in terms of device performance and stability, yielding a power conversion efficiency (PCE) of 18.27 % and a T80 lifetime exceeding 10000 h. Moreover, incorporation of QBr-PEI-50 in fully stretchable inverted OSCs yielded a PCE of 14.01 %, and 80 % of the initial PCE was maintained after 21 % strain, showcasing its potential for wearable electronics.

Unusual Cross-Conjugation in Cyclic Dipeptide-Based Building Blocks for Donor-Acceptor Semiconducting Conjugated Polymers

Cross conjugation, though prevalent in many organic compounds, is typically considered less effective for electron delocalization compared to linear conjugation. Consequently, it is rarely used as the backbone structure for semiconducting conjugated polymers. In this study, we designed and synthesized a novel building block, TIDP, which features a central cyclic dipeptide with cross conjugation characteristics. Strong intramolecular hydrogen bonding interactions confer TIDP with a highly rigid and coplanar conformation. Importantly, theoretical calculations reveal that π electrons are well delocalized across the entire structure, despite its low aromaticity. Conjugated polymers incorporating TIDP exhibit high charge carrier mobilities, demonstrating the effective π electrons delocalization of this innovative building block. Our findings show that with rational design, cross conjugation can achieve effective π electrons delocalization, providing a valuable approach for developing high-performance conjugated polymers for organic electronic materials.

Understanding photochemical degradation mechanisms in photoactive layer materials for organic solar cells

Over the past decades, the field of organic solar cells (OSCs) has witnessed a significant evolution in materials chemistry, which has resulted in a remarkable enhancement of device performance, achieving efficiencies of over 19%. The photoactive layer materials in OSCs play a crucial role in light absorption, charge generation, transport and stability. To facilitate the scale-up of OSCs, it is imperative to address the photostability of these electron acceptor and donor materials, as their photochemical degradation process remains a challenge during the photo-to-electric conversion. In this review, we present an overview of the development of electron acceptor and donor materials, emphasizing the crucial aspects of their chemical stability behavior that are linked to the photostability of OSCs. Throughout each section, we highlight the photochemical degradation pathways for electron acceptor and donor materials, and their link to device degradation. We also discuss the existing interdisciplinary challenges and obstacles that impede the development of photostable materials. Finally, we offer insights into strategies aimed at enhancing photochemical stability and discuss future directions for developing photostable photo-active layers, facilitating the commercialization of OSCs.

Highly selective and additive-free Pd(OAc)2/CPP catalyzed hydroaminocarbonylation of alkynes

Herein, the synthesis of branched α,β-unsaturated amides by a hydroaminocarbonylation reaction of alkynes with various amine substrates such as aromatic amines, aliphatic amines, solid amine sources like NH4HCO3, and even strongly basic piperidines is reported, using a Pd(OAc)2/hybrid N-heterocyclic carbene-phosphine-phosphine (CPP) catalytic system. The reactions feature no additives, wide substrate scope, high selectivity (b/l > 99 : 1) and excellent yields. Mechanistic studies have disclosed that the reaction takes place via a palladium hydride pathway. CPP adopts a hybrid bidentate ligand conformation with a carbene-phosphine coordination mode, wherein one phosphorus atom remains externally accessible, potentially serving as a stabilizing auxiliary during catalytic cycles.

Strategies to Enhance the Electrochromic Properties of Conjugated Polymers Bearing Pyromellitic Diimide Acceptors

A series of conjugated polymers bearing thiophene-based donors and pyromellitic diimide (PMDI) acceptor were prepared, and their electrochromic (EC) properties were studied via using fabricated thin-film EC devices. It was observed that structurally regular alternating polymers with fewer (1 and 2) thiophene donors do not exhibit any EC properties while increasing the number of donors eventually led to the emergence of orange-red-to-green colour switching. On this basis, two more random co-polymers containing higher donor-to-acceptor ratios were synthesized to further improve EC switching properties. The two polymers, which bear a PMDI-to-thiophene ratio of ca. 1 : 7 and 1 : 8, revealed orange red-to-blue colour switching and generally improved optical contrasts and switching speeds in both the visible and near infra-red (NIR) region. In addition, the subtle modulation of polymer colour and hue via variation of the number of thiophene donors was evident through colorimetric study. This work therefore demonstrates the potential and possibility of using the PMDI acceptor unit to construct EC-active conjugated polymers, and considerations for future tuning of colour and switching performances.

An unprecedented roll-off ratio in high-performing red TADF OLED emitters featuring 2,3-indole-annulated naphthalene imide and auxiliary donors

The capability of organic emitters to harvest triplet excitons via a thermally activated delayed fluorescence (TADF) process has opened a new era in organic optoelectronics. Nevertheless, low brightness, and consequently an insufficient roll-off ratio, constitutes a bottleneck for their practical applications in the domain of organic light-emitting diodes (OLEDs). To address this formidable challenge, we developed a new design of desymmetrized naphthalimide (NMI) featuring an annulated indole with a set of auxiliary donors on its periphery. Their perpendicular arrangement led to minimized HOMO-LUMO overlap, resulting in a low energy gap (ΔE ST = 0.05-0.015 eV) and efficient TADF emission with a photoluminescence quantum yield (PLQY) ranging from 82.8% to 95.3%. Notably, the entire set of dyes (NMI-Ind-TBCBz, NMI-Ind-DMAc, NMI-Ind-PXZ, and NMI-Ind-PTZ) was utilized to fabricate TADF OLED devices, exhibiting yellow to red electroluminescence. Among them, red-emissive NMI-Ind-PTZ, containing phenothiazine as an electron-rich component, revealed predominant performance with a maximum external quantum efficiency (EQE) of 23.6%, accompanied by a persistent luminance of 38 000 cd m-2. This results in a unique roll-off ratio (EQE10 000 = 21.6%), delineating a straightforward path for their commercial use in lighting and display technologies.

Synthesis of Amides via the Amination of Aldehydes with Hydroxylamines Promoted by TBAF·3H2O

A metal-free, mild, and efficient method for the synthesis of amides has been developed from the amination of aldehydes with hydroxylamines promoted by TBAF·3H2O in the presence of KOH. Control experiments showed that the nitrone was the intermediate of this amination. By this method, a series of amides, biologically active compounds bebenil and a COX inhibitor were obtained in moderate to good yields.

Naphthalene diimide-Annulated Heterocyclic Acenes: Synthesis, Electrochemical and Semiconductor Properties and their Multifaceted Applications

Acenes and Naphthalene Diimides (NDIs) stand as distinguished classes of organic compounds, each possessing unique and intriguing properties that have garnered significant attention across various scientific disciplines. Acenes, characterized by linearly fused aromatic rings, have captivated researchers due to their diverse electronic structures and promising applications in materials science. On the other hand, NDIs, known for their distinctive electron-accepting properties, exhibit remarkable versatility in fields ranging from organic electronics, supramolecular to spin chemistry. In this review, we navigate through the fascinating realms of both acenes and NDIs before converging our focus on the highly diverse and distinctive subgroup of NDI-annulated heterocyclic acenes. This potentially important subgroup, has emerged as a subject of intense investigation, encapsulating their fascinating synthesis, optical and electrochemical characteristics, and multifaceted applications that span the realms of chemistry, physics, and biology. Through the exploration of their synthetic strategies, unique properties, and diverse applications, this review aims to offer a comprehensive understanding of the pivotal role played by NDI-based heterocyclic acenes in contemporary multidisciplinary research and technological innovation.

Pre-Endcapping of Hyperbranched Polymers toward Intrinsically Stretchable Semiconductors with Good Ductility and Carrier Mobility

The advancement of semiconducting polymers stands as a pivotal milestone in the quest to realize wearable electronics. Nonetheless, endowing semiconductor polymers with stretchability without compromising their carrier mobility remains a formidable challenge. This study proposes a "pre-endcapping" strategy for synthesizing hyperbranched semiconducting polymers (HBSPs), aiming to achieve the balance between carrier mobility and stretchability for organic electronics. The findings unveil that the aggregates formed by the endcapped hyperbranched network structure not only ensure efficient charge transport but also demonstrate superior tensile resistance. In comparison to linear conjugated polymers, HBSPs exhibit substantially larger crack onset strains and notably diminished tensile moduli. It is evident that the HBSPs surpass their linear counterparts in terms of both their semiconducting and mechanical properties. Among HBSPs, HBSP-72h-2.5 stands out as the preeminent candidate within the field of inherently stretchable semiconducting polymers, maintaining 93% of its initial mobility even when subjected to 100% strain (1.41 ± 0.206 cm2 V-1 s-1). Furthermore, thin film devices of HBSP-72h-2.5 remain stable after undergoing repeated stretching and releasing cycles. Notably, the mobilities are independent of the stretching directions, showing isotropic charge transport behavior. The preliminary study makes this "pre-endcapping" strategy a potential candidate for the future design of organic materials for flexible electronic devices.

Functionalized Phenanthrene Imide-Based Polymers for n-Type Organic Thin-Film Transistors

High-performing n-type polymers are crucial for the advance of organic electronics field, however strong electron-deficient building blocks with optimized physicochemical properties for constructing them are still limited. The imide-functionalized polycyclic aromatic hydrocarbons (PAHs) with extended π-conjugated framework, high electron deficiency and good solubility serve as promising candidates for developing high-performance n-type polymers. Among the PAHs, phenanthrene (PhA) features a well-delocalized aromatic π-system with multiple modifiable active sites . However, the PhA-based imides are seldom studied, mainly attributed to the synthetic challenge. Herein, we report two functionalized PhAs, CPOI and CPCNI, by simultaneously incorporating imide with carbonyl or dicyanomethylene onto PhA. Notably, the dicyanomethylene-modified CPCNI exhibits a well stabilized LUMO energy level (-3.84 eV), attributed to the synergetic inductive effect from imide and cyano groups. Subsequently, based on CPOI and CPCNI, two polymers PCPOI-Tz and PCPCNI-Tz were developed. Applied to organic thin-film transistors, owing to the strong electron-deficiency of CPCNI, polymer PCPCNI-Tz shows an improved electron mobility and largely decreased threshold voltage compared with PCPOI-Tz. This work affords two structurally novel electron-deficient building blocks and highlights the effectiveness of dual functionalization of PhAs with strong electron-withdrawing groups for devising n-type polymers.

Supramolecular complexation of C60 with branched polyethylene

Fullerene C60 is a ubiquitous material for application in organic electronics and nanotechnology, due to its desirable optoelectronic properties including good molecular orbital alignment with electron-rich donor materials, as well as high and isotropic charge carrier mobility. However, C60 possesses two limitations that hinder its integration into large-scale devices: (1) poor solubility in common organic solvents leading to expensive device processing, and (2) poor optical absorbance in the visible portion of the spectrum. Covalent functionalization has long been the standard for introducing structural tunability into molecular design, but non-covalent interactions have emerged as an alternative strategy to tailor C60-based materials, offering a versatile and tuneable alternative to novel functional materials and applications. In this work, we report a straightforward non-covalent functionalization of C60 with a branched polyethylene (BPE), which occurs spontaneously in dilute chloroform solution under ambient conditions. A detailed characterization strategy, based on UV-vis spectroscopy and size-exclusion chromatography was performed to verify and investigate the structure of the C60+BPE complex. Among others, our work reveals that the supramolecular complex has an order of magnitude higher molecular weight than its C60 and BPE constituents and points towards oxidation as the driving force behind complexation. The C60+BPE complex also possesses significantly broadened optical absorbance compared to unfunctionalized C60, extending further into the visible portion of the spectrum. This non-covalent approach presents an inexpensive route to address the shortcomings of C60 for electronic applications, situating the C60+BPE complex as a promising candidate for further investigation in organic electronic devices.

Copper-catalyzed synthesis of primary amides through reductive N-O cleavage of dioxazolones

A new method for the synthesis of primary amides is developed, in which dioxazolones are treated with a copper catalyst under mild reaction conditions. A broad scope of dioxazolones is exhibited as well as dioxazolones containing biologically active structural motifs. These robust and mild reaction conditions allow the transformation of dioxazolones to primary amides, in which sensitive functional groups such as hydroxyl, aldehyde, trialkylsilyl, and unsaturated carbon units are tolerated with excellent chemoselectivity.

Cyano-Functionalized Pyrazine: A Structurally Simple and Easily Accessible Electron-Deficient Building Block for n-Type Organic Thermoelectric Polymers

Developing low-cost and high-performance n-type polymer semiconductors is essential to accelerate the application of organic thermoelectrics (OTEs). To achieve this objective, it is critical to design strong electron-deficient building blocks with simple structure and easy synthesis, which are essential for the development of n-type polymer semiconductors. Herein, we synthesized two cyano-functionalized highly electron-deficient building blocks, namely 3,6-dibromopyrazine-2-carbonitrile (CNPz) and 3,6-Dibromopyrazine-2,5-dicarbonitrile (DCNPz), which feature simple structures and facile synthesis. CNPz and DCNPz can be obtained via only one-step reaction and three-step reactions from cheap raw materials, respectively. Based on CNPz and DCNPz, two acceptor-acceptor (A-A) polymers, P(DPP-CNPz) and P(DPP-DCNPz) are successfully developed, featuring deep-positioned lowest unoccupied molecular orbital (LUMO) energy levels, which are beneficial to n-type organic thin-film transistors (OTFTs) and OTEs performance. An optimal unipolar electron mobility of 0.85 and 1.85 cm2  V-1  s-1 is obtained for P(DPP-CNPz) and P(DPP-DCNPz), respectively. When doped with N-DMBI, P(DPP-CNPz) and P(DPP-DCNPz) show high n-type electrical conductivities/power factors of 25.3 S cm-1 /41.4 μW m-1  K-2 , and 33.9 S cm-1 /30.4 μW m-1  K-2 , respectively. Hence, the cyano-functionalized pyrazine CNPz and DCNPz represent a new class of structurally simple, low-cost and readily accessible electron-deficient building block for constructing n-type polymer semiconductors.

Binary All-polymer Solar Cells with a Perhalogenated-Thiophene-Based Solid Additive Surpass 18 % Efficiency

Morphological control of all-polymer blends is quintessential yet challenging in fabricating high-performance organic solar cells. Recently, solid additives (SAs) have been approved to be capable in tuning the morphology of polymer: small-molecule blends improving the performance and stability of devices. Herein, three perhalogenated thiophenes, which are 3,4-dibromo-2,5-diiodothiophene (SA-T1), 2,5-dibromo-3,4-diiodothiophene (SA-T2), and 2,3-dibromo-4,5-diiodothiophene (SA-T3), were adopted as SAs to optimize the performance of all-polymer organic solar cells (APSCs). For the blend of PM6 and PY-IT, benefitting from the intermolecular interactions between perhalogenated thiophenes and polymers, the molecular packing properties could be finely regulated after introducing these SAs. In situ UV/Vis measurement revealed that these SAs could assist morphological character evolution in the all-polymer blend, leading to their optimal morphologies. Compared to the as-cast device of PM6 : PY-IT, all SA-treated binary devices displayed enhanced power conversion efficiencies of 17.4-18.3 % with obviously elevated short-circuit current densities and fill factors. To our knowledge, the PCE of 18.3 % for SA-T1-treated binary ranks the highest among all binary APSCs to date. Meanwhile, the universality of SA-T1 in other all-polymer blends is demonstrated with unanimously improved device performance. This work provide a new pathway in realizing high-performance APSCs.

Sufficient driving force for quinoidal isoindigo-based diradicaloids with tunable diradical characters

Stable organic π-conjugated diradcialoids with tunable diradical characters can profoundly affect emerging technology. Over the past years, great efforts have been devoted to studying the structure-diradical character relationship in diradicaloids. Herein, a series of quinoidal isoindigo (IID) compounds with different attached terminal end groups were designed. Detailed analysis focuses on elucidating the driving force for evoking and enhancing the diradical character in the quinoidal IID systems. The arylene units of the IID core and the bridged aromatic units determine the contribution of the open-shell diradical form in the ground state. Diradical character y0 correlates well with bond length alternation (BLA), the total HOMA, and the total NICS(1)zz, and it is tuned by bridged aromatic units and terminal end groups in symmetric systems. The zwitterionic character weakens the diradical character in asymmetric systems to different extents. This work contributes to the deep understanding of evoking and enhancing the diradical character in quinoidal IID-based diradcialoids, providing useful guidelines to produce new molecules with desirable properties.

Organic Transistors Based on Highly Crystalline Donor-Acceptor π-Conjugated Polymer of Pentathiophene and Diketopyrrolopyrrole

Oligomers and polymers consisting of multiple thiophenes are widely used in organic electronics such as organic transistors and sensors because of their strong electron-donating ability. In this study, a solution to the problem of the poor solubility of polythiophene systems was developed. A novel π-conjugated polymer material, PDPP-5Th, was synthesized by adding the electron acceptor unit, DPP, to the polythiophene system with a long alkyl side chain, which facilitated the solution processing of the material for the preparation of devices. Meanwhile, the presence of the multicarbonyl groups within the DPP molecule facilitated donor-acceptor interactions in the internal chain, which further improved the hole-transport properties of the polythiophene-based material. The weak forces present within the molecules that promoted structural coplanarity were analyzed using theoretical simulations. Furthermore, the grazing incidence wide-angle X-ray scanning (GIWAXS) results indicated that PDPP-5Th features high crystallinity, which is favorable for efficient carrier migration within and between polymer chains. The material showed hole transport properties as high as 0.44 cm2 V-1 s-1 in conductivity testing. Our investigations demonstrate the great potential of this polymer material in the field of optoelectronics.

Incorporation of Diketopyrrolopyrrole into Polythiophene for the Preparation of Organic Polymer Transistors

Polythiophene, as a class of potential electron donor units, is widely used in organic electronics such as transistors. In this work, a novel polymeric material, PDPPTT-FT, was prepared by incorporating the electron acceptor unit into the polythiophene system. The incorporation of the DPP molecule assists in improving the solubility of the material and provides a convenient method for the preparation of field effect transistors via subsequent solution processing. The introduction of fluorine atoms forms a good intramolecular conformational lock, and theoretical calculations show that the structure displays excellent co-planarity and regularity. Grazing incidence wide-angle X-ray (GIWAXS) results indicate that the PDPPTT-FT is highly crystalline, which facilitates carrier migration within and between polymer chains. The hole mobility of this π-conjugated material is as high as 0.30 cm2 V-1 s-1 in organic transistor measurements, demonstrating the great potential of this polymer material in the field of optoelectronics.

NiH-catalyzed C-N bond formation: insights and advancements in hydroamination of unsaturated hydrocarbons

The formation of C-N bonds is a fundamental aspect of organic synthesis, and hydroamination has emerged as a pivotal strategy for the synthesis of essential amine derivatives. In recent years, there has been a surge of interest in metal hydride-catalyzed hydroamination reactions of common alkenes and alkynes. This method avoids the need for stoichiometric organometallic reagents and overcomes problems associated with specific organometallic compounds that may impact functional group compatibility. Notably, recent developments have brought to the forefront olefinic hydroamination and hydroamidation reactions facilitated by nickel hydride (NiH) catalysis. The inclusion of suitable chiral ligands has paved the way for the realization of asymmetric hydroamination reactions in the realm of olefins. This review aims to provide an in-depth exploration of the latest achievements in C-N bond formation through intermolecular hydroamination catalyzed by nickel hydrides. Leveraging this innovative approach, a diverse range of alkene and alkyne substrates can be efficiently transformed into value-added compounds enriched with C-N bonds. The intricacies of C-N bond formation are succinctly elucidated, offering a concise overview of the underlying reaction mechanisms. It is our aspiration that this comprehensive review will stimulate further progress in NiH-catalytic techniques, fine-tune reaction systems, drive innovation in catalyst design, and foster a deeper understanding of the underlying mechanisms.

Selenophene Substitution Enabled High-Performance n-Type Polymeric Mixed Ionic-Electronic Conductors for Organic Electrochemical Transistors and Glucose Sensors

High-performance n-type polymeric mixed ionic-electronic conductors (PMIECs) are essential for realizing organic electrochemical transistors (OECTs)-based low-power complementary circuits and biosensors, but their development still remains a great challenge. Herein, by devising two novel n-type polymers (f-BTI2g-SVSCN and f-BSeI2g-SVSCN) containing varying selenophene contents together with their thiophene-based counterpart as the control, it is demonstrated that gradually increasing selenophene loading in polymer backbones can simultaneously yield lowered lowest unoccupied molecular orbital levels, boosted charge-transport properties, and improved ion-uptake capabilities. Therefore, a remarkable volumetric capacitance (C*) of 387.2 F cm-3 and a state-of-the-art OECT electron mobility (µe,OECT ) of 0.48 cm2 V-1 s-1 are synchronously achieved for f-BSeI2g-SVSCN having the highest selenophene content, yielding an unprecedented geometry-normalized transconductance (gm,norm ) of 71.4 S cm-1 and record figure of merit (µC*) value of 191.2 F cm-1 V-1 s-1 for n-type OECTs. Thanks to such excellent performance of f-BSeI2g-SVSCN-based OECTs, a glucose sensor with a remarkably low detection limit of 10 nMm and decent selectivity is further implemented, demonstrating the power of selenophene substitution strategy in enabling high-performance n-type PMIECs for biosensing applications.

Coplanar Conformational Structure of π-Conjugated Polymers for Optoelectronic Applications

Hierarchical structure of conjugated polymers is critical to dominating their optoelectronic properties and applications. Compared to nonplanar conformational segments, coplanar conformational segments of conjugated polymers (CPs) demonstrate favorable properties for applications as a semiconductor. Herein, recent developments in the coplanar conformational structure of CPs for optoelectronic devices are summarized. First, this review comprehensively summarizes the unique properties of planar conformational structures. Second, the characteristics of the coplanar conformation in terms of optoelectrical properties and other polymer physics characteristics are emphasized. Five primary characterization methods for investigating the complanate backbone structures are illustrated, providing a systematical toolbox for studying this specific conformation. Third, internal and external conditions for inducing the coplanar conformational structure are presented, offering guidelines for designing this conformation. Fourth, the optoelectronic applications of this segment, such as light-emitting diodes, solar cells, and field-effect transistors, are briefly summarized. Finally, a conclusion and outlook for the coplanar conformational segment regarding molecular design and applications are provided.

Dipyridyl-Fused Quinoxalineimide (DPQI): A Strong Electron-Withdrawing Building Block for n-Type Polymer Semiconductors

Exploration of new electron-withdrawing building blocks plays a key role in the development of n-type organic semiconductors. Herein, a strong electron-withdrawing building block, dipyridyl-fused quinoxalineimide (DPQI), was successfully designed and synthesized. Single-crystal structure reveals that DPQI molecule possesses a completely planar backbone, which is beneficial for charge transport. For comparison, dibenzo-fused quinoxalineimide (DBQI) was also synthesized. The frontier molecular orbital (FMO) energy levels downshift with the incorporation of nitrogen atoms onto the π-conjugated backbone of quinoxalineimide. Two acceptor-acceptor (or all-acceptor) polymers P(BTI-DBQI) and P(BTI-DPQI) based on DBQI and DPQI were synthesized, respectively. Two polymers exhibit deep lowest-unoccupied molecular orbital (LUMO) levels (~-3.5 eV). Additionally, P(BTI-DPQI) exhibits unipolar n-type charge transport with μe of 1.4×10-4  cm2  V-1  s-1 in the organic field-effect transistors (OFET), which render them highly attractive for developing n-type semiconductors device. This work demonstrates that DPQI is a promising building block for constructing n-type polymer semiconductors.

Conjugated Polymers from Direct Arylation Polycondensation of 3,4-Difluorothiophene-Substituted Aryls: Synthesis and Properties

3,4-Difluorothiophene-substituted aryls, i.e., 1,4-bis(3,4-difluorothiophen-2-yl)-benzene (Ph-2FTh), 1,4-bis(3,4-difluorothiophen-2-yl)-2,5-difluorobenzene (2FPh-2FTh), and 4,7-bis(3,4-difluorothiophen-2-yl)-2,1,3-benzothiadiazole (BTz-2FTh), are synthesized as C─H monomers for the synthesis of conjugated polymers (CPs) via direct arylation polycondensation (DArP) with diketopyrrolopyrrole (DPP) and isoindigo (IID) derivatives as C─Br monomers. The Gibbs free energies of activation for direct arylation (ΔG298 K , kcal mol-1 ) for α─C─H bonds of thiophene moieties as calculated by density functional theory (DFT) are 14.3, 16.5, and 16.4 kcal mol-1 for Ph-2FTh, 2FPh-2FTh and BTz-2FTh, respectively, meaning that inserting an electron-deficient unit in 3,3',4,4'-tetrafluoro-2,2'-bithiophene (4FBT, ΔG298K : 14.6 kcal mol-1 ) may cause a reactivity decrease of the C─H monomers. Photophysical and semiconducting properties of the resulting six CPs (i.e., DPP-Ph, DPP-2FPh, DPP-BTz, 2FIID-Ph, 2FIID-2FPh, and 2FIID-BTz) are characterized in detail. DPP-based CPs show ambipolar transport properties while IID-based ones exhibited n-type behavior owing to the deeper frontier molecular orbital energy levels of IID-based CPs. With source/drain electrodes modified with polyethylenimine ethoxylated, n-channel organic thin-film transistors with maximum electron mobility of 0.40, 0.54, 0.29, 0.05, 0.16, and 0.01 cm2 V-1 s-1 for DPP-Ph, DPP-2FPh, DPP-BTz, 2FIID-Ph, 2FIID-2FPh, and 2FIID-BTz, respectively, are fabricated. DPP-2FPh exhibits the best device performance due to the good film morphology and the highest intermolecular packing order.

Polyfluorinated Naphthalene-bis-hydrazimide for Solution-Grown n-Type Semiconducting Films

Naphthalene tetracarboxylic diimides (NDIs), possessing low-lying and tunable LUMO levels, are of wide interest for their aptitude to provide cost-effective, flexible, and environmentally stable n-type organic semiconductors through simple solution processing. NDI-based aromatic hydrazidimides are herein studied in relation to their chemical and environmental stability and as spin-coated stable thin films. In the case of the pentafluorinated residue, these were found to be crystalline, highly oriented, and molecularly flat (roughness = 0.3 nm), based on optical and atomic force microscopy, X-ray diffraction in specular and grazing incidence geometry, and X-ray reflectivity measurements. A new polymorph, previously undetected during the isolation of bulk powders or in their controlled thermal treatments, is found in the thin film and was metrically and structurally characterized from 2D GIWAXS patterns (monoclinic, P2/c, a = 17.50; b = 4.56; c = 14.24 Å; β = 84.8°). This new thin-film phase, TF-F5, is formed no matter whether silicon, glass, or polymethylmethacrylate substrates are used, thus opening the way to the preparation of solution-grown flexible semiconducting films. The TF-F5 films exhibit a systematic and rigorous molecular alignment with both orientation and packing favorable to electron mobility (μ = 0.02 cm2 V-1 s-1). Structural and morphological differences are deemed responsible for the absence of measurable conductivity in thin films of polyfluorinated analogues bearing -CF3 residues on the hydrazidimide aromatic rings.

Effect of N-phenyl substituent on thermal, optical, electrochemical and luminescence properties of 3-aminophthalimide derivatives

The seven N-phthalimide derivatives substituted with the amine group at the 3-C position in the phenylene ring were synthesized. The effect of N-substituent chemical structure was investigated. The thermal, electrochemical and optical studies were performed and supported by the density functional theory calculations (DFT). The electrochemical investigations of the synthesized low-molecular phthalimides revealed the one oxidation and reduction process with the HOMO energy level under - 5.81 eV and energy-band gap below 3 eV. The N-phthalimide derivatives were emitted light in a blue spectral region in solutions (in polar and non-polar) with the quantum yield between 2 and 68%, dependent on the substituent at the nitrogen atom, solvent and concentration. The N-phthalimide derivatives were emissive also in a solid state as a thin film and powder. They were tested as a component of the active layer with PVK:PBD matrix and as an independent active layer in the organic light-emitting diodes. The registered electroluminescence spectra exhibited the maximum emission band in the 469-505 nm range, confirming the possibility of using N-phthalimides with PVK:PBD matrix as the blue emitters.

Photo-Induced Carbonylation of Aryl Bromides for the Synthesis of Aryl Esters and Amides Under Transition Metal-Free Conditions

In this work, we developed a photo-induced carbonylation of aryl bromides under transition metal-free conditions. The reaction shows good activity with alcohol and amine nucleophiles. Various esters and amides were formed from aryl halides and alcohols and amines under mild conditions in moderate to good yields.

Molecular Design Concept for Enhancement Charge Carrier Mobility in OFETs: A Review

In the last two decades, organic field-effect transistors (OFETs) have garnered increasing attention from the scientific and industrial communities. The performance of OFETs can be evaluated based on three factors: the charge transport mobility (μ), threshold voltage (Vth), and current on/off ratio (Ion/off). To enhance μ, numerous studies have concentrated on optimizing charge transport within the semiconductor layer. These efforts include: (i) extending π-conjugation, enhancing molecular planarity, and optimizing donor-acceptor structures to improve charge transport within individual molecules; and (ii) promoting strong aggregation, achieving well-ordered structures, and reducing molecular distances to enhance charge transport between molecules. In order to obtain a high charge transport mobility, the charge injection from the electrodes into the semiconductor layer is also important. Since a suitable frontier molecular orbitals' level could align with the work function of the electrodes, in turn forming an Ohmic contact at the interface. OFETs are classified into p-type (hole transport), n-type (electron transport), and ambipolar-type (both hole and electron transport) based on their charge transport characteristics. As of now, the majority of reported conjugated materials are of the p-type semiconductor category, with research on n-type or ambipolar conjugated materials lagging significantly behind. This review introduces the molecular design concept for enhancing charge carrier mobility, addressing both within the semiconductor layer and charge injection aspects. Additionally, the process of designing or converting the semiconductor type is summarized. Lastly, this review discusses potential trends in evolution and challenges and provides an outlook; the ultimate objective is to outline a theoretical framework for designing high-performance organic semiconductors that can advance the development of OFET applications.

Research Progress of Organic Field-Effect Transistor Based Chemical Sensors

Due to their high sensitivity and selectivity, chemical sensors have gained significant attention in various fields, including drug security, environmental testing, food safety, and biological medicine. Among them, organic field-effect transistor (OFET) based chemical sensors have emerged as a promising alternative to traditional sensors, exhibiting several advantages such as multi-parameter detection, room temperature operation, miniaturization, flexibility, and portability. This review paper presents recent research progress on OFET-based chemical sensors, highlighting the enhancement of sensor performance, including sensitivity, selectivity, stability, etc. The main improvement programs are improving the internal and external structures of the device, as well as the organic semiconductor layer and dielectric structure. Finally, an outlook on the prospects and challenges of OFET-based chemical sensors is presented.

Semiconducting Polymers Based on Simple Electron-Deficient Cyanated trans-1,3-Butadienes for Organic Field-Effect Transistors

Developing high-performance but low-cost n-type polymers remains a significant challenge in the commercialization of organic field-effect transistors (OFETs). To achieve this objective, it is essential to design the key electron-deficient units with simple structures and facile preparation processes, which can facilitate the production of low-cost n-type polymers. Herein, by sequentially introducing fluorine and cyano functionalities onto trans-1,3-butadiene, we developed a series of structurally simple but highly electron-deficient building blocks, namely 1,4-dicyano-butadiene (CNDE), 3-fluoro-1,4-dicyano-butadiene (CNFDE), and 2,3-difluoro-1,4-dicyano-butadiene (CNDFDE), featuring a highly coplanar backbone and deep-positioned lowest unoccupied molecular orbital (LUMO) energy levels (-3.03-4.33 eV), which render them highly attractive for developing n-type semiconducting polymers. Notably, all these electron-deficient units can be easily accessed by a two-step high-yield synthetic procedure from low-cost raw materials, thus rendering them highly promising candidates for commercial applications. Upon polymerization with diketopyrrolopyrrole (DPP), three copolymers were developed that demonstrated unipolar n-type transport characteristics in OFETs with the highest electron mobility of >1 cm2  V-1  s-1 . Hence, CNDE, CNFDE, and CNDFDE represent a class of novel, simple, and efficient electron-deficient units for constructing low-cost n-type polymers, thereby providing valuable insight for OFET applications.

Flexible and Stretchable Organic Electrochemical Transistors for Physiological Sensing Devices

Flexible and stretchable bioelectronics provides a biocompatible interface between electronics and biological systems and has received tremendous attention for in situ monitoring of various biological systems. Considerable progress in organic electronics has made organic semiconductors, as well as other organic electronic materials, ideal candidates for developing wearable, implantable, and biocompatible electronic circuits due to their potential mechanical compliance and biocompatibility. Organic electrochemical transistors (OECTs), as an emerging class of organic electronic building blocks, exhibit significant advantages in biological sensing due to the ionic nature at the basis of the switching behavior, low driving voltage (<1 V), and high transconductance (in millisiemens range). During the past few years, significant progress in constructing flexible/stretchable OECTs (FSOECTs) for both biochemical and bioelectrical sensors has been reported. In this regard, to summarize major research accomplishments in this emerging field, this review first discusses structure and critical features of FSOECTs, including working principles, materials, and architectural engineering. Next, a wide spectrum of relevant physiological sensing applications, where FSOECTs are the key components, are summarized. Last, major challenges and opportunities for further advancing FSOECT physiological sensors are discussed.

Self-Doped n-Type Quinoidal Compounds with Good Air Stability and High Electrical Conductivity for Organic Electronics

Air stable n-type conductive molecules with high electrical conductivities and excellent device performance have important applications in organic electronics, but their synthesis remains challenging. Herein, we report three self-doped n-type conductive molecules, designated QnNs, with a closed-shell quinoidal backbone and alkyl amino chains of different lengths. The QnNs are self-doped by intermolecular electron transfer from the amino groups to the quinoidal backbone. This process is ascertained unambiguously by experiments and theoretical calculations. The use of a quinoidal structure effectively improves the self-doping level, and thus increases the electrical conductivity of self-doped n-type conductive molecules achieved by a closed-shell structure from<10-4  S cm-1 to>0.03 S cm-1 . Furthermore, the closed-shell quinoidal structure results in good air stability of the QnNs, with half-lives>73 days; and Q4N shows an electrical conductivity of 0.019 S cm-1 even after exposure to air for 120 days. When applying Q6N as the cathode interlayer in organic solar cells (OSCs), an outstanding power conversion efficiency of up to 18.2 % was obtained, which represents one the best results in binary OSCs.

An In-Situ Cyanidation Strategy To Access Tetracyanodiacenaphthoanthracene Diimides with High Electron Mobilities Exceeding 10 cm2 V-1 s-1

A family of novel highly π-extended tetracyano-substituted acene diimides, named as tetracyanodiacenaphthoanthracene diimides (TCDADIs), have been synthesized using a facile four-fold Knoevenagel condensation strategy. Unlike conventional cyano substitution reactions, our approach enables access to a large π-conjugated backbone with the in-situ formation of four cyano substitutents at room temperature while avoiding extra cyano-functionalization reactions. TCDADIs decorated with different N-alkyl substituents present good solubility, near-coplanar backbones, good crystallinity, and low-lying lowest unoccupied molecular orbital energies of -4.33 eV, all of which contribute to desirable electron-transport performance when applied in organic field-effect transistors (OFET). The highest electron mobility of an OFET based on a 2-hexyldecyl-substituted TCDADI single crystal reaches 12.6 cm2  V-1  s-1 , which is not only among the highest values for the reported n-type organic semiconductor materials (OSMs) but also exceeds that of most n-type OSMs decorated with imide units.

Manipulating the Alkyl Chains of Naphthodithiophene Imide-Based Polymers to Concurrently Boost the Efficiency and Stability of Organic Solar Cells

Morphology instability holds the major responsibility for efficiency degradation of organic solar cells (OSCs). However, how to develop polymer donors simultaneously with high efficiency and excellent morphology stability remains challenging. Herein, we reported naphtho[2,1-b:3,4-b']dithiophene-5,6-imide (NDTI)-based new polymers PNDT1 and PNDT2. The alkyl chain engineering leads to high crystallinity, high hole mobility (>10-3 cm2 V-1 S-1), and nanofibrous film morphology, which enable PNDT2 to exhibit an efficiency of 18.13% and a remarkable FF value of 0.80. Moreover, the NDTIs have short π-π stacking and abundant short interactions, and their polymers exhibit superior morphological stability. Therefore, the PNDT2-based OSCs exhibit much better device stability than that of PNDT1, PAB-α, and benchmark polymers PM6 and D18. This work suggests the great importance of the large conjugated backbone of the monomer and alkyl chain engineering to develop high-performance and morphology-stable polymers for OSCs.

Oxidative-Reductive Near-Infrared Electrochromic Switching Enabled by Porous Vertically Stacked Multilayer Devices

Here, we demonstrate for the first time the ability of a porous π-conjugated semiconducting polymer film to enable facile electrolyte penetration through vertically stacked redox-active polymer layers, thereby enabling electrochromic switching between p-type and/or n-type polymers. The polymers P1 and P2, with structures diketopyrrolopyrrole (DPP)-π_bridge-3,4,-ethylenedioxythiophene (EDOT)-π_bridge [π_bridge = 2,5-thienyl for P1 and π_bridge = 2,5-thiazolyl for P2] are selected as the p-type polymers and N2200 (a known naphthalenediimide-dithiophene semiconductor) as the n-type polymer. Single-layer porous and dense (control) polymer films are fabricated and extensively characterized using optical microscopy, atomic force microscopy, scanning electron microscopy, and grazing incidence wide-angle X-ray scattering. The semiconducting films are then incorporated into single and multilayer electrochromic devices (ECDs). It is found that when a p-type (P2) porous top layer is used in a multilayer ECD, it enables electrolyte penetration to the bottom layer, enabling oxidative electrochromic switching of the P1 bottom layer at low potentials (+0.4 V versus +1.2 V with dense P2). Importantly, when using a porous P1 as the top layer with an n-type N2200 bottom layer, dynamic oxidative-reductive electrochromic switching is also realized. These results offer a proof of concept for development of new types of multilayer electrochromic devices where precise control of the semiconductor film morphology and polymer electronic structure is essential.

Self-Doping Naphthalene Diimide Conjugated Polymers for Flexible Unipolar n-Type OTFTs

The development of high-performance organic thin-film transistor (OTFT) materials is vital for flexible electronics. Numerous OTFTs are so far reported but obtaining high-performance and reliable OTFTs simultaneously for flexible electronics is still challenging. Herein, it is reported that self-doping in conjugated polymer enables high unipolar n-type charge mobility in flexible OTFTs, as well as good operational/ambient stability and bending resistance. New naphthalene diimide (NDI)-conjugated polymers PNDI2T-NM17 and PNDI2T-NM50 with different contents of self-doping groups on their side chains are designed and synthesized. The effects of self-doping on the electronic properties of resulting flexible OTFTs are investigated. The results reveal that the flexible OTFTs based on self-doped PNDI2T-NM17 exhibit unipolar n-type charge-carrier properties and good operational/ambient stability thanks to the appropriate doping level and intermolecular interactions. The charge mobility and on/off ratio are fourfold and four orders of magnitude higher than those of undoped model polymer, respectively. Overall, the proposed self-doping strategy is useful for rationally designing OTFT materials with high semiconducting performance and reliability.

Hydrogen-free palladium-catalyzed intramolecular anti-Markovnikov hydroaminocarbonylation of 2-(1-methylvinyl)anilines

The palladium-catalyzed intramolecular hydroaminocarbonylation of 2-(1-methylvinyl)aniline derivatives has been achieved using dppp (1,3-bis(diphenylphosphino)propane) as a ligand under hydrogen-free conditions. The reaction involves the generation of an active palladium hydride species with a catalytic amount of TsOH. This amide bond formation reaction was applied to the synthesis of various 4-substituted 3,4-dihydroquinolone derivatives with both high yield and regioselectivity.

Asymmetric Wettability Mediated Patterning of Single Crystalline Nematic Liquid Crystal and P-N Heterojunction Toward a Broadband Photodetector

The well aligned and precise patterning of liquid crystals (LCs) are considered as two key challenges for large-scale and high-efficiency integrated optoelectronic devices. However, owing to the uncontrollable liquid flow and dewetting process in the conventional techniques, most of the reported research is mainly focused on simple sematic LCs, which are composed of terthiophenes or benzothieno[3, 2-b][1] benzothiophene backbone; only a few works are carried out on the complicated LCs. Herein, an efficient strategy was introduced to control the liquid flow and alignment of LCs and realized precise and high-quality patterning of A-π-D-π-A BTR, based on the asymmetric wettability interface. Through this strategy, the large-area and well-aligned BTR microwires array was fabricated, which exhibited highly ordered molecular packing and improved charge transport performance. Furthermore, the integration of BTR and PC₇₁BM was achieved to manufacture uniform P-N heterojunction arrays, which still possessed highly ordered alignment of BTR. On the basis of these aligned heterojunction arrays, the high-performance photodetector exhibited an excellent responsivity of 27.56 A W^-1 and a specific detectivity of 2.07 × 10¹² Jones. This research not only provides an efficient strategy for the fabrication of aligned micropatterns of LCs but also gives a novel insight for the fabrication of high-quality micropatterns of the P-N heterojunction toward integrated optoelectronics.

Molecular Design and Crystal Chemistry of Polyfluorinated Naphthalene-bis-phenylhydrazimides with Superior Thermal and Polymorphic Stability and High Solution Processability

Naphthalene tetracarboxylic diimides (NDIs) are highly promising air-stable n-type molecular semiconductor candidates for flexible and cost-effective organic solar cells and thermoelectrics. Nonetheless, thermal and polymorphic stabilities of environmentally stable NDIs in the low-to-medium temperature regime (<300 °C) remain challenging properties. Structural, thermal, spectroscopic, and computational features of polyfluorinated NDI-based molecular solids (with up to 14 F atoms per NDI molecule) are discussed upon increasing the fluorination level. Slip-stacked arrangement of the NDI cores with suitable π-π stacking and systematically short interplanar distances (<3.2 Å) are found. All these materials exhibit superior thermal stability (up to 260 °C or above) and thermal expansion coefficients indicating a response compatible with flexible polymeric substrates. Optical bandgaps increase from 2.78 to 2.93 eV with fluorination, while LUMO energy levels decrease down to -4.37 eV, as shown per DFT calculations. The compounds exhibit excellent solubility of 30 mg mL^-1 in 1,4-dioxane and DMF.

p-Methoxybenzyl-Radical-Promoted Chemoselective Protection of sec-Alkylamides

The hitherto difficult site-selective p-methoxybenzylation of secondary amides using p-methoxybenzylated alkylsilyl peroxides as a novel p-methoxybenzylation agent under copper catalysis is reported. The reaction proceeds under mild reaction conditions in a highly chemoselective manner. This approach was successfully applied to the site-selective p-methoxybenzylation of peptides.

Supramolecular Phthalimide Networks Via Tandem Diels-Alder Reaction-Aromatization Using Biomass-Derived Furanic Dienes

The design and synthesis of phthalimide derivatives are important goals for applications in fields such as pharmaceutical science and optoelectronics. In the present study, a facile and convenient synthetic pathway (no heat or acid/catalyst needed) is devised to produce phthalimides from a biomass-derived furan by directly introducing an N-carbamate group at the C-2 position of the furan ring via thermal Curtius rearrangement. The electron-donating N-carbamate group increases the energy level of the highest occupied molecular orbital of the furan diene, resulting in a significant increase of the rate of the Diels-Alder reaction with maleimide compared to the conventional furfuryl furan. Interestingly, the Diels-Alder adduct smoothly undergoes aromatization (dehydration) to generate the phthalimide motif. It is shown that the biomass-derived phthalimides can produce supramolecular gels and act as sensors of basic anions like F^- and CN^- . The novel synthetic pathway to phthalimide derivatives from a biomass-derived furan can potentially be used to develop novel phthalimide motifs for a variety of applications.

n-Type Polymer Semiconductors Based on Dithienylpyrazinediimide

The development of n-type organic semiconductors critically relies on the design and synthesis of highly electron-deficient building blocks with good solubility and small steric hindrance. We report here a strongly electron-deficient dithienylpyrazinediimide (TPDI) and its n-type semiconducting polymers. The pyrazine substitution leads to the resulting polymers with much lower-lying lowest unoccupied molecular orbital (LUMO) levels and improved backbone planarity compared to the reported dithienylbenzodiimide (TBDI)- and fluorinated dithienylbenzodiimide (TFBDI)-based polymer analogues, thus yielding n-type transport character with an electron mobility up to 0.44 cm² V^-1 s^-1 in organic thin-film transistors. These results demonstrate that dithienylpyrazinediimide is a highly promising electron-deficient building block for constructing high-performance n-type polymers and the incorporation of pyrazine into imide-functionalized (hetero)arenes is an effective strategy to develop n-type polymers with deep-lying frontier molecular orbital (FMO) levels for organic optoelectronic devices.