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Photocatalytic hydrogen evolution from water using fluorene and dibenzothiophene sulfone conjugated microporous and linear polymers
摘要： Three series of conjugated microporous polymers (CMPs) were studied as photocatalysts for hydrogen production from water using a sacrificial hole scavenger. In all cases, dibenzo[b,d]thiophene sulfone polymers outperformed their fluorene analogs. A porous network, S-CMP3, showed the highest hydrogen evolution rate of 6076 μmol h-1 g-1 (λ > 295 nm) and 3106 μmol h-1 g-1 (λ > 420 nm), with an external quantum efficiency of 13.2% at 420 nm. S-CMP3 outperforms its linear structural analog, P35, while in other cases, non-porous linear polymers are superior to equivalent porous networks. This suggests that microporosity might be beneficial for sacrificial photocatalytic hydrogen evolution, if suitable linkers are used that do not limit charge-transport and the material can be wetted by water as studied here by water sorption and quasi-elastic neutron scattering.
关键词： fluorene,sacrificial hole scavenger,conjugated microporous polymers,photocatalytic hydrogen evolution,dibenzo[b,d]thiophene sulfone
更新于2025-09-04 15:30:14
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End-cap Group Engineering of a Small Molecule Non-Fullerene Acceptor: The Influence of Benzothiophene Dioxide
摘要： In this study, a sulfonyl-containing end-capping moiety, benzothiophene dioxide, was selected to prepare the nonfullerene acceptor ITBC. ITBC has an acceptor?donor?acceptor (A-D-A) structure, with indacenodithieno[3,2-b]thiophene (IDTT) as the electron-rich core moiety. The strong electron-withdrawing sulfonyl acceptor units leads to extended UV?vis absorption into the near-IR region and relatively low frontier molecular orbital energy levels (LUMO/HOMO: ?4.13 eV/?5.61 eV) with a narrow bandgap of 1.48 eV. These values compare favorably to the well-studied small molecule acceptor 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile end-capped indacenodithieno[3,2-b]thiophene (ITIC). A power conversion e?ciency of 4.17% was achieved by fabricating organic solar cells with the ?uorinated conjugated polymer FTAZ as the donor and ITBC as the acceptor. These results indicate that benzothiophene dioxide is a novel electron-withdrawing end-capping unit for ITBC, and can be used as an electron acceptor for organic solar cells.
关键词： fused conjugated system,non-fullerene acceptor,e?cient photovoltaics,benzothiophene dioxide,organic solar cells
更新于2025-09-04 15:30:14
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Tuning the Potential of Electron Extraction from Microbes with Ferrocene‐Containing Conjugated Oligoelectrolytes
摘要： Synthetic systems that facilitate electron transport across cellular membranes are of interest in bio-electrochemical technologies such as bio-electrosynthesis, waste water remediation, and microbial fuel cells. The design of second generation redox-active conjugated oligoelectrolytes (COEs) bearing terminal cationic groups and a π-delocalized core capped by two ferrocene units is reported. The two COEs, DVFBO and F4-DVFBO, have similar membrane affinity, but fluorination of the core results in a higher oxidation potential (422 ± 5 mV compared to 365 ± 4 mV vs Ag/AgCl for the neutral precursors in chloroform). Concentration-dependent aggregation is suggested by zeta potential measurements and confirmed by cryogenic transmission electron microscopy. When the working electrode potential (ECA) is poised below the oxidation potential of the COEs (ECA = 200 mV) in three-electrode electrochemical cells containing Shewanella oneidensis MR-1, addition of DVFBO and F4-DVFBO produces negligible biocurrent enhancement over controls. At ECA = 365 mV, DVFBO increases steady-state biocurrent by 67 ± 12% relative to controls, while the increase with F4-DVFBO is 30 ± 5%. Cyclic voltammetry supports that DVFBO increases catalytic biocurrent and that F4-DVFBO has less impact, consistent with their oxidation potentials. Overall, electron transfer from microbial species is modulated via tailoring of the COE redox properties.
关键词： conjugated oligoelectrolytes,bio-electrochemical systems,transmembrane electron transfer,exoelectrogenic microbes,redox-active molecules
更新于2025-09-04 15:30:14
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Pump-Push-Probe for Ultrafast All-Optical Switching: The Case of a Nanographene Molecule
摘要： In the last two decades, the three-beam pump–push–probe (PPP) technique has become a well-established tool for investigating the multidimensional configurational space of a molecule, as it permits disclosure of precious information about the multiple and often complex deactivation pathways of the excited molecule. From the spectroscopic point of view, such a tool has revealed details about the efficiency of charge pair generation and conformational relaxation in π-conjugated molecules and macromolecules. In addition, PPP is effectively utilized for modulating the gain signal in conjugated materials by taking advantage of the spectral overlap between stimulated emission and charge absorption in those systems. However, the relatively low stability of conjugated polymers under intense photoexcitation is a crucial limitation for their real employment in plastic optical fibers (POFs) and for signal control applications. Herein, the role of PPP for achieving ultrafast all-optical switching in π-conjugated systems is highlighted. Furthermore, new experimental data on optical switching of a newly synthesized nanographene molecule, namely dibenzo[hi,st]ovalene (DBOV), is reported. The superior environmental and photostability of DBOV and, in general, of graphene nanostructures can represent a great advantage for their effective applications in POFs and information and communications technology.
关键词： ultrafast optical switching,pump–push–probe,conjugated polymers,ultrafast spectroscopy,nanographene
更新于2025-09-04 15:30:14
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Dithienobenzimidazole‐containing conjugated donor–acceptor polymers: Synthesis and characterization
摘要： The synthesis of two new conjugated polymers based on the relatively under-exploited monomer, 5,8-dibromo-2-[5-(2-hexyldecyl)-2-thienyl]-1H-dithieno[3,2-e:20,30-g]benzimidazole (dithienobenzimidazole, DTBI), and either 4,7-bis[4-hexyl-5-(trimethylstannyl)-2-thienyl]-2,1,3-benzothiadiazole (BTD) or 2,6-bis(trimethylstannyl)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophene (BDT) is described. The polymers were synthesized via Stille polycondensation and characterized by traditional methods (1H NMR, gel-permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, thermal gravimetric analysis, differential scanning calorimetry, ultraviolet–visible spectroscopy, photoluminescence, and cyclic voltammetry). Prior to their synthesis, trimer structures were modeled by DFT calculations facilitating a further understanding of the systems’ electronic and geometric structure. Polymers were titrated with acid and base to take advantage of their amphiprotic imidazole moiety and their optical response monitored with ultraviolet–visible spectroscopy. Finally, pristine polymer thin-films were treated with acid and base to evaluate (de)protonation’s effect on system electronics, but thin-film degradation was encountered.
关键词： addition polymerization,synthesis,conjugated,conducting polymers,semiconducting polymer,dithienobenzimidazole,ionomers,donor–acceptor
更新于2025-09-04 15:30:14
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Synthesis and characterization of heterocyclic conjugated polymers containing planar Benzo[c]cinnoline and tetraazapyrene structures for organic field-effect transistor application
摘要： Heterocyclic conjugated polymers BZCTVT and TAPTVT containing tetraazapyrene (TAP) and benzo[c]cinnoline (BZC), respectively, were prepared by using Stille coupling polymerization in microwave reactor. TAP and BZC act as acceptors and thiophene-vinylene-thiophene (TVT) acts as donors. Alkylated thiophene is the linker between acceptor and donor. This is the first time that tetraazapyrene was incorporated into conjugated polymers. The films of BZCTVT and TAPTVT showed maximum absorption wavelength at 522 and 534 nm, respectively. From cyclic voltammertry measurement, TAPTVT and BZCTVT exhibited low LUMO (-3.61 and -3.47 eV) and HOMO (-5.64 and -5.63 eV) energy levels. Even though BZC and TAP were planar structures, BZCTVT and TAPTVT showed large dihedral angles between alkylated thiophene and TVT (10.8-22.6o), and between alkylated thiophene and BZC and TAP (22.2-30.3o) based on their simulated energy-minimized geometry. The bottom-gate, top-contact OFETs based on TAPTVT and BZCTVT exhibited only p-channel behavior with hole mobility of 4.63 × 10-4 and 1.04 × 10-4 cm2 V-1 s-1 and current on/off ratios greater than 104 after thermal annealing. Grazing incidence X-ray diffraction (GIXRD) patterns suggested that thin films of TAPTVT and BZCTVT preferred edge-on orientation.
关键词： heterocyclic conjugated polymers,organic field-effect transistor,tetraazapyrene,Stille coupling polymerization,benzo[c]cinnoline
更新于2025-09-04 15:30:14
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Electron Transport with Mobility, μ > 86 cm2/Vs, in a 74 nm Long Polyfluorene
摘要： The mobility of charges on conjugated polymers is a fundamentally important feature of these materials, but most fall far short of transport that might lead one to call them “molecular wires”. A commonly identified bottleneck is flexible dihedral angles between repeat units. Here we find a very high mobility, μ > 86 cm2/Vs, for electrons attached to polyfluorene polymers in isooctane, despite the presence of varied dihedral angles. The present data suggests that interactions with the surrounding medium may be a principal determinant of charge mobility.
关键词： mobility,molecular wires,conjugated polymers,polyfluorene,electron transport
更新于2025-09-04 15:30:14
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Stable, carrier separation tailorable conjugated microporous polymers as a platform for highly efficient photocatalytic H2 evolution
摘要： The molecular design of highly photo-functional polymers with high charge separation efficiency and wide spectral absorption are long term quest for photocatalysis. Herein, we design and develop a series of nitrogen-containing conjugated microporous polymers (N-CMPs) with tailored donor-acceptor units for enhancing charge separation and light harvesting for visible light photocatalytic H2 production. By alternating the substitution position (o-, m-, or p-) and the number of electron donor (carbazole, diphenylamine) and acceptor (cyano) units on the 3D-core structure, a series of N-CMPs with adjustable donor-acceptor (D-A) charge separation efficiencies and tuneable band gaps in the range of 1.64-2.29 eV were obtained, enabling the precise control of the photocatalytic activity at the molecular level. The optimized N-CMP (4-CzPN) exhibits a higher visible light H2 production rate at 2103.2 μmol/h·g and the apparent quantum yield (AQY) at 420 nm reaches 6.4%. Furthermore, the 4-CzPN photocatalyst maintains excellent durability and recycling performance under 25 h continued light irradiation. The outstanding photocatalytic performance of the optimized N-CMPs with D-A structure is attributed to the enhanced polarity and conjugated degree of their core structure, which promotes charge separation and light absorption.
关键词： light absorption,donor-acceptor units,photocatalytic H2 production,conjugated microporous polymers,charge separation
更新于2025-09-04 15:30:14
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Creation of micropores by RAFT copolymerization of conjugated multi-vinyl cross-linkers
摘要： We report a new methodology that allows for forming micropores in hierarchically porous polymers by employing the reversible addition–fragmentation chain transfer (RAFT) copolymerization of conjugated multi-vinyl cross-linkers with styrene. Using divinylbenzene, 4,4’-divinylbiphenyl, 1,3,5-tris(4-vinylphenyl) benzene and tetrakis(4-vinylbiphenyl)methane as cross-linkers, the RAFT copolymerization was carried out in the presence of polylactide macro-chain transfer agents. During the polymerization, microphase separation occurred spontaneously to produce cross-linked block polymer precursors with a bicontinuous morphology composed of polylactide and cross-linked polystyrene microdomains. Hierarchically porous polymers with strong fluorescence were successfully derived by polylactide etching. We demonstrate that the rigid conjugated structure of the cross-linkers with a high cross-linking density is critical for creating the micropores and for stabilizing the mesopores that are templated by the polylactide domain.
关键词： hierarchically porous polymers,polylactide macro-chain transfer agents,RAFT copolymerization,micropores,conjugated multi-vinyl cross-linkers
更新于2025-09-04 15:30:14
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Sequence-definition in stiff conjugated oligomers
摘要： The concept of sequence-definition in the sense of polymer chemistry is introduced to conjugated, rod-like oligo(phenylene ethynylene)s via an iterative synthesis procedure. Specifically, monodisperse sequence-defined trimers and pentamers were prepared via iterative Sonogashira cross-coupling and deprotection. The reaction procedure was extended to tetra- and pentamers for the first time yielding a monodisperse pentamer with 18% and a sequence-defined pentamer with 3.2% overall yield. Furthermore, three novel trimers with a 9H-fluorene building block at predefined positions within the phenylene ethynylene chain were synthesised in 23–52% overall yields. Hence, it was confirmed that a functionality of interest can be incorporated selectively at a pre-defined position of these monodisperse oligomers. All respective intermediate structures were fully characterised by proton and carbon NMR, mass spectrometry, size-exclusion chromatography, and IR spectroscopy. Additionally, thermal and optical transitions are reported for the different oligomers.
关键词： fluorene,monodisperse,Sonogashira cross-coupling,sequence-definition,conjugated oligomers
更新于2025-09-04 15:30:14