Donor Building Blocks Research Articles

Discovery of Trypanosoma brucei inhibitors enabled by a unified synthesis of diverse sulfonyl fluorides

Sets of electrophilic probes are generally prepared using a narrow toolkit of robust reactions, which tends to limit both their structural and functional diversity. A unified synthesis of skeletally-diverse sulfonyl fluorides was developed that relied upon photoredox-catalysed dehydrogenative couplings between hetaryl sulfonyl fluorides and hydrogen donor building blocks. A set of 32 diverse probes was prepared, and then screened against Trypanosoma brucei. Four of the probes were found to have sub-micromolar anti-trypanosomal activity. A chemical proteomic approach, harnessing an alkynylated analogue and broad-spectrum fluorophosphonate tools, provided insights into the observed anti-trypanosomal activity, which likely stems from covalent modification of multiple protein targets. It is envisaged that the unified diversity-oriented approach may enable the discovery of electrophilic probes that have value in the elucidation of biological and biomedical mechanisms.

Enhancement of thermoelectric performance of thienoisoindigo based D‐A conjugated polymers through the incorporation of 3,4‐ethylenedioxythiophene as donor unit

AbstractWith the good planarity of conjugated backbone and high charge carrier mobilities, thienoisoindigo (TIIG)‐based polymers show great potential in organic electronic devices. In this work, two TIIG‐based D‐A conjugated polymers (PTIIG‐3T and PTIIG‐2T‐EDOT) were designed and synthesized, which exhibit high lying highest occupied molecular orbital (HOMO) energy level and can be facilely doped by FeCl3. Compared with PTIIG‐3T, one thiophene unit in the donor building block is replaced by 3,4‐ethylenedioxythiophene (EDOT) in PTIIG‐2T‐EDOT, and PTIIG‐2T‐EDOT shows a higher HOMO level with slightly higher coplanarity than PTIIG‐3T, which induce an enhancement in electrical conductivity after oxidation doping. After proper doping, doped PTIIG‐2T‐EDOT film achieved a higher TE power factor of 17.9 μW m−1 K−2 than that of PTIIG‐3T due to its higher conductivity. The results indicate that TIIG unit is a promising building block for future high‐performance conjugated polymers for thermoelectric applications, and incorporation of the EDOT unit into D‐A conjugated polymers could be an effective way to develop high performance thermoelectric polymers.

Management of Donor and Acceptor Building Blocks in Dopant-Free Polymer Hole Transport Materials for High-Performance Perovskite Solar Cells.

The dominant hole transport material (HTM) in state-of-the-art perovskite solar cells (PSCs) is Spiro-OMeTAD, which needs to be doped using hydrophilic dopants to improve its hole mobility and conductivity, resulting in inferior device stability. Here, we propose an effective molecular design strategy to construct dopant-free polymer HTMs by selecting four structurally related polymers and investigating their structure-property relationship. It is found that the donor and acceptor units with longitudinal conjugate extension, such as BDT-T and BDD, could not only enhance the planarity of the conjugated polymer backbone and tune the energy levels but also promote the face-on orientation, resulting in superior charge extraction and transport. The optimized device utilizing dopant-free polymer HTM shows a high open-circuit voltage of 1.19 V and a champion efficiency of 24.04 % with greatly improved operational stability, making it among the best performance PSCs based on dopant-free HTMs.

Management of Donor and Acceptor Building Blocks in Dopant‐Free Polymer Hole Transport Materials for High‐Performance Perovskite Solar Cells

AbstractThe dominant hole transport material (HTM) in state‐of‐the‐art perovskite solar cells (PSCs) is Spiro‐OMeTAD, which needs to be doped using hydrophilic dopants to improve its hole mobility and conductivity, resulting in inferior device stability. Here, we propose an effective molecular design strategy to construct dopant‐free polymer HTMs by selecting four structurally related polymers and investigating their structure–property relationship. It is found that the donor and acceptor units with longitudinal conjugate extension, such as BDT‐T and BDD, could not only enhance the planarity of the conjugated polymer backbone and tune the energy levels but also promote the face‐on orientation, resulting in superior charge extraction and transport. The optimized device utilizing dopant‐free polymer HTM shows a high open‐circuit voltage of 1.19 V and a champion efficiency of 24.04 % with greatly improved operational stability, making it among the best performance PSCs based on dopant‐free HTMs.

Synthesis, photophysical, electrochemical and computational studies of novel 2-aminoimidazolones with D-π-A framework

Two novel 2-aminoimidazolone derivatives based on donor-linker-acceptor (D-π-A) architecture (imidazoLUMS1 and imidazoLUMS2) have been synthesized and characterized by standard spectroscopic techniques. The donor building block in these compounds comprises of 4-benzylidene-2-(piperidin-1-yl)-1H-imidazol-5(4H)-one and 4-(thiophen-2-ylmethylene)-2-((3,4,5-trimethoxyphenyl)amino)-1H-imidazol-5(4H)-one respectively, while cyanoacetic acid was used as the electron acceptor linked to donor through a π-conjugated spacer. Synthetic methodology involved our multicomponent reaction following by Suzuki coupling and, Knoevenagel condensation reactions. ImidazoLUMS1 (λmax = 436 nm) and imidazoLUMS2 (λmax of 482 nm) showed a bathochromic shift of 58 nm and 104 nm with respect to their parent molecule 1 (λmax = 378 nm). The observed stoke shifts (Δλ = 134 nm and Δλ = 112 nm) and band gap values 2.40 eV and 2.26 eV support thermodynamic feasibility for intramolecular charge transfer character from donor to acceptor moiety. DFT studies, performed on GAUSSIAN 09, for the charge properties show their suitability for optoelectronic devices and an excellent correlation between experimental and computational data.

Towards a Systematic Understanding of the Influence of Temperature on Glycosylation Reactions.

Glycosidic bond formation is a continual challenge for practitioners. Aiming to enhance the reproducibility and efficiency of oligosaccharide synthesis, we studied the relationship between glycosyl donor activation and reaction temperature. A novel semi‐automated assay revealed diverse responses of members of a panel of thioglycosides to activation at various temperatures. The patterns of protecting groups and the thiol aglycon combine to cause remarkable differences in temperature sensitivity among glycosyl donor building blocks. We introduce the concept of donor activation temperature to capture experimental insights, reasoning that glycosylations performed below this reference temperature evade deleterious side reactions. Activation temperatures enable a simplified temperature treatment and facilitate optimization of glycosyl donor usage. Isothermal glycosylation below the activation temperature halved the equivalents of building block required in comparison to the standard “ramp” regime used in solution‐ and solid‐phase oligosaccharide synthesis to‐date.

Monitoring the dependence of the photovoltaic properties of dye-sensitized solar cells from the structure of D–A–π–A-type sensitizers with a 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazole donor building block

The use of D–A–π–A organic sensitizers based on 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazole as a new donor building block for DSSCs made it possible to achieve the best power conversion efficiency of 5.68%.

Ladder-Type Fused Benzodithiophene Extended along the Short-Axis Direction as a New Donor Building Block for Efficient Organic Solar Cells.

Ladder-type fused aromatic systems are important core structures of small molecule acceptors for organic solar cells (OSCs). In this study, a new ladder-type donor building block, based on the benzo[1,2-b:4,5-b']dithiophene (BDT) unit where the 3,7 positions of the BDT thiophene rings and the 3' position of the thiophene rings of the vertical BDT were fused to construct a seven-ring core structure named f-DTBDT, was investigated. In the f-DTBDT structure, the fusion of the BDT core and the thiophene rings at the 4,8 positions of BDT constrains all of the aromatic rings in a coplanar structure. The newly designed f-DTBDT was successfully employed as a core donor building block and conjugated with three electron-withdrawing acceptors (2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (2HIC), 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC), and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2ClIC)) as acceptor-donor-acceptor (A-D-A)-type acceptor materials for OSCs. Characterization results showed that the three synthesized A-D-A acceptors of DTBDT-IC, DTBDT-4F, and DTBDT-4Cl have high absorption behavior in the vis-NIR region as result of an intramolecular charge transfer interaction engendered by f-DTBDT and the ending group. The absorption regions of the acceptors were complementary with that of polymer PM6. Also, the frontier orbital energy levels of the new acceptors and wide-band-gap PM6 are well matched. Bulk heterojunction OSCs were fabricated using PM6 and the acceptors, and the highest power conversion efficiency (PCE) of 10.15% was obtained when using PM6:DTBDT-4F as the active layer.

Tert-Butyl Bis(4′-(Hexyloxy)-[1,1′-biphenyl]-4-yl)carbamate

New donor building blocks, i.e., triarylamino derivatives, are of great interest for the production of organic photovoltaic materials. In this communication, bis(4′-(hexyloxy)-[1,1′-biphenyl]-4-yl)amine was synthesized in a two-step process via hydrolysis of its tert-butyl carbamate derivative. tert-Butyl bis(4′-(hexyloxy)-[1,1′-biphenyl]-4-yl)carbamate was obtained by Suzuki cross-coupling reaction of tert-butyl bis(4-bromophenyl)carbamate and (4-(hexyloxy)phenyl)boronic acid in the presence of tetrakis(triphenylphosphine)palladium(0). The structure of newly synthesized compounds was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C-NMR, IR and UV spectroscopy and mass-spectrometry.

One-Dimensional Bimetallic Lantern Complex

As the scale of microelectronic circuit devices approaches the atomic limit, the study of molecular-based wires and magnets has become more prevalent. Lantern (or paddle-wheel) complexes with conventional {O(S),O} donor building block came into being, dozens of new lantern complexes have been prepared at present. The use of organic monomers to connect such complex building block to form metal coordination polymers with rigid open framework and tunable properties has become a research hotspot. Such polymers can be assembled in a one-dimensional array to produce unique electronic and magnetic properties for use in vapor color sensors, luminescent materials, magnetic resonance imaging, etc., to create diversified and multidisciplinary research fields.

Fused Dithienopicenocarbazole Enabling High Mobility Dopant-Free Hole-Transporting Polymers for Efficient and Stable Perovskite Solar Cells.

As a critical component in perovskite solar cells (PSCs), hole-transporting materials (HTMs) have been extensively explored. To develop efficient dopant-free HTMs for PSCs, a decent hole mobility (>10-3 cm2 V-1 s-1) is critically essential, which is, however, seldom reported. In this work, we introduce two novel donor-acceptor (D-A) type conjugated polymers (PDTPC-1 and PDTPC-2) with narrow bandgap unit, i.e., fused dithienopicenocarbazole (DTPC), as the donor building block and benzo[c][1,2,5]thiadiazole derivatives as the acceptors. The highly planar and strong electron-donating DTPC endows the polymers with superior hole mobility up to ∼4 × 10-3 cm2 V-1 s-1. Because of the better energy alignment with perovskite and excellent film-forming property, PSCs with PDTPC-1 as HTM show an appreciably enhanced PCE of ∼17% in dopant-free PSCs along with improved device stability as opposed to PDTPC-2. Our work revealed for the first time that the introduction of narrow bandgap DTPC in D-A polymers could achieve remarkably high hole mobility in the pristine form, favoring the application in dopant-free PSCs.

Colored Janus Nanocylinders Driven by Supramolecular Coassembly of Donor and Acceptor Building Blocks.

Janus nanocylinders exhibit nanometric dimensions, a high aspect ratio, and two faces with different chemistries (Janus character), making them potentially relevant for applications in optics, magnetism, catalysis, surface nanopatterning, or interface stabilization, but they are also very difficult to prepare by conventional strategies. In the present work, Janus nanocylinders were prepared by supramolecular coassembly in water of two different polymers functionalized with complementary assembling units. The originality of our approach consists in combining charge transfer complexation between electron-rich and electron-poor units with hydrogen bonding to (1) drive the supramolecular formation of one-dimensional structures (cylinders), (2) force the two polymer arms on opposite sides of the cylinders independently of their compatibility, resulting in Janus nanoparticles, and (3) detect coassembly through a color change of the solution upon mixing of the functional polymers.

Carboxylate substituted pyrazine: A simple and low-cost building block for novel wide bandgap polymer donor enables 15.3% efficiency in organic solar cells

In addition to high power conversion efficiency (PCE) and good stability, the low-cost of photovoltaic materials is also very important for the practical application of organic solar cells (OSCs). Herein, we synthesized a carboxylate substituted pyrazine-based electron-deficient building block (DTCPz) with a simple structure and low synthetic cost, and then developed a novel wide bandgap polymer donor PFBCPZ. Due to the synergistic electron-withdrawing effects of the fluorination in donor unit (BDT-TF) and esterification and C=N double-bond in DTCPz unit, PFBCPZ shows a deeper HOMO level of −5.60 eV, a strong intermolecular π-π interaction, good crystallinity and stacking, and high hole-mobility of 2.11 × 10 − 3 cm 2 V − 1 s −1 . Matched with a low bandgap acceptor IT-4F, excellent charge transfer, weak recombination, and small non-radiative energy loss in OSCs was achieved, resulting in an impressive fill factor of 0.785 and a high open-circuit voltage of 0.92 V. As a result, a PCE of up to 15.3% is obtained in OSCs, which is the highest value in the IT-4F-based binary OSCs so far and indicates that low-cost DTCPz with a simple structure is a promising building block to construct high-performance polymer donors for application in efficient OSCs. • A novel wide bandgap polymer donor PFBCPZ was synthesized. • The novel building block (DTCPz) showed easily synthesized routs with cheap raw material. • The OSC based on PFBCPZ:IT-4F exhibited excellent performance with 15.3% efficiency. • The efficiency is the highest value in the IT-4F-based binary OSCs so far.

Conductive Polymers: Synergistically Improved Molecular Doping and Carrier Mobility by Copolymerization of Donor–Acceptor and Donor–Donor Building Blocks for Thermoelectric Application (Adv. Funct. Mater. 40/2020)

Conductive Polymers: Synergistically Improved Molecular Doping and Carrier Mobility by Copolymerization of Donor–Acceptor and Donor–Donor Building Blocks for Thermoelectric Application (Adv. Funct. Mater. 40/2020)

Synergistically Improved Molecular Doping and Carrier Mobility by Copolymerization of Donor–Acceptor and Donor–Donor Building Blocks for Thermoelectric Application

AbstractIn this work, it is demonstrated that random copolymerization is a simple but effective strategy to obtain new conductive copolymers as high‐performance thermoelectric materials. By using a polymerizing acceptor unit diketopyrropyrrole with donor units thienothiophene and oligo ethylene glycol substituted bithiophene (g32T), it is found that strong interchain donor–acceptor interactions ensure good film crystallinity for charge transport, while donor–donor type building blocks contribute to effective charge transfers. Hall effect measurements show that the high electrical conductivity results from increased free carriers with simultaneously improved mobility reaching over 1 cm2 V−1 s−1. The synergistic effect of improved molecular doping and carrier mobility, as well as a high Seebeck coefficient ascribed to the structural disorder along polymer chains via random copolymerization, results in an impressive power factor up to 110 µW K−2 m−1 which is 10 times higher than that of solution‐processed polythiophenes.

Thienoquinolinone as a new building block for wide bandgap semiconducting polymer donors for organic solar cells

A new heterocyclic aromatic structure, thieno[3,2-c]quinolin-4(5H)-one (TQO), was designed and synthesized as an electron-accepting building block for donor–acceptor-type copolymers.

9-(p-Tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole—A new donor building-block in the design of sensitizers for dye-sensitized solar cells

The novel donor building-block - 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole was designed and employed in the synthesis of dye-sensitized solar cell (DSSCs). An effective, high-yielding synthesis of 4,6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9-(p-tolyl)-1,2,3,4,4a,9a-hexahydrocarbazole from 1,2,3,4,4a,9a-hexahydrocarbazole was realized. Three new metal-free organic sensitizers, containing the new donor building block were prepared by a stepwise approach from 4,7-dibromobenzo[c][1,2,5]chacogenadiazoles. A 2,1,3-Benzothiadiazole dye containing hexahydrocarbazole donor, thiophene as π-spacer and cyanoacrylate as anchoring electron acceptor showed photovoltaic properties higher than the well-known WS-2 sensitizer with PCE = 5.86 %. Although benzoxa- and –selenadiazole dyes have a bathochromic shift (24−30 nm) in the UV–vis spectra, and smaller energy gap Eg (about 0.1 eV), they have lower photovoltaic parameters, including PCE of 1.5–2.3 %. Introducing a new donor 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole into the construction of the DSSCs has broadened possibilities for the optimization of their photovoltaic properties.

Effects of the length and steric hindrance of π-bridge on molecular configuration and optoelectronic properties of diindole[3,2-b:4,5-b′]pyrrole-based small molecules

Three new A-π-D-π-A type small molecules (DIP-T, DIP-HT, and DIP-HTT) employing diindole[3,2-b:4,5-b′]pyrrole (DIP) as the electron-rich donor (D) block, indenedione as the electron-deficient acceptor (A) group, and thiophene, 3-hexylthiophene, or 4-hexyl-2,2′-dithiophene as the conjugated π-bridge, are designed, synthesized and characterized as donor materials for organic solar cells (OSCs). The effects of the length and steric hindrance of the thiophene-containing π-bridges on the molecular configuration, optical, electrochemical and charge-transport properties were investigated by theory calculations, UV–vis spectroscopy, cyclic voltammetry, and the space-charge-limited current method, respectively. These DIP-based small molecules (SMs) show excellent solubility and good thermal stability. DIP-T with thiophene as π-bridge shows wider and stronger absorption, higher-lying HOMO energy level, higher hole mobility and superior active layer morphology in comparison with that of DIP-HT and DIP-HTT with 3-hexylthiophene and 4-hexyl-2,2′-dithiophene as the conjugated π-bridge, respectively. As a result, the optimized OSC based on DIP-T exhibits an obviously higher power conversion efficiency (PCE) of 4.65% with relative to the other two SMs. So far, this is the first report of developing the A-π-D-π-A type SMs with a DIP donor core for application in organic electronic devices. Our results indicate that the pentacyclic DIP can be a potential and attractive donor building block for developing efficient A-π-D-π-A type SMs donor materials.

Design and synthesis of stable indigo polymer semiconductors for organic field-effect transistors with high fluoride sensitivity and selectivity.

We report the design and synthesis of two novel indigo donor–acceptor (D–A) polymers, PIDG-T-C20 and PIDG-BT-C20, comprising an indigo moiety that has intramolecular hydrogen-bonds as the acceptor building block and thiophene (T) and bithiophene (BT) as the donor building block, respectively. PIDG-T-C20 and PIDG-BT-C20 exhibited characteristic p-type semiconductor performance, achieving hole mobilities of up to 0.016 and 0.028 cm2 V−1 s−1, respectively, which are highest values reported for indigo-based polymers. The better performing PIDG-BT-C20 was used for the fabrication of water-gated organic field-effect transistors (WGOFETs), which showed excellent stability at ambient conditions. The PIDG-BT-C20-based WGOFETs exhibited rapid response when fluoride ions were introduced to the water gate dielectric, achieving a limit of detection (LOD) of 0.40 mM. On the other hand, the devices showed much lower sensitivities towards other halide ions with the order of relative response: F− ≫ Cl− > Br− > I−. The high sensitivity and selectivity of PIDG-BT-C20 to fluoride over other halides is considered to be realized through the strong interaction of the hydrogen atoms of the N–H groups in the indigo unit with fluoride ions, which alters the intramolecular hydrogen-bonding arrangement, the electronic structures, and thus the charge transport properties of the polymer.

Using automated glycan assembly (AGA) for the practical synthesis of heparan sulfate oligosaccharide precursors.

Herein we report synthesis of complex heparan sulfate oligosaccharide precursors by automated glycan assembly using disaccharide donor building blocks. Rapid access to a hexasaccharide was achieved through iterative solid phase glycosylations on a photolabile resin using Glyconeer™, an automated oligosaccharide synthesiser, followed by photochemical cleavage and glycan purification using simple flash column chromatography.