Reaction Site Designation by Intramolecular Electric Field in Tröger's-Base-Derived Conjugated Microporous Polymer for Near-Unity Selectivity of CO2 Photoconversion

Molecular engineering of donor-acceptor-type conjugated microporous polymers for dual effective photocatalytic production of hydrogen and hydrogen peroxide

Conjugated microporous polymers (CMPs) have garnered increasing attention as emerging polymeric photocatalysts for solar-driven hydrogen (H2) and hydrogen peroxide (H2O2) production, owing to their high surface areas, extended π-conjugation, and tunable architectures. In pursuit of this goal, we undertook the rational design and synthesis of two donor-acceptor CMPs, PyPh-DBZS and ANTh-DBZS, via Suzuki coupling polymerization. These CMPs integrate electron-rich pyrene (PyPh) or tetrathienoanthracene (ANTh) donor units with the electron-deficient benzothiophene S,S-dioxide (DBZS) acceptor moiety, enabling efficient dual photocatalytic generation of H2 and H2O2. Notably, both polymers exhibit excellent thermal stability with T10 values exceeding 590 °C and high char yields at 800 °C. PyPh-DBZS CMP exhibited an exceptional H2 evolution rate (HER) of 133 241 μmol g-1 h-1. At the same time, ANTh-DBZS CMP achieved superior H2O2 production (24.51 mM g-1), demonstrating structure-dependent charge separation under visible light irradiation. These results offer critical design principles for the rational emergence of new-generation CMPs photocatalysts, paving the way toward efficient and sustainable H2 and H2O2 production.

Acid/Base-Responsive Circularly Polarized Luminescence Emitters with Configurationally Stable Nitrogen Stereogenic Centers

A way to prevent the fast configurational interconversion of tertiary amines is to invoke Tröger's base analogs, which display methano- or ethano-bridged diazocine cores fused to aromatic rings. These derivatives are configurationally stable, even in acidic media when their structures bear ethylene bridges. Here, a two- to three-step synthesis is presented of methano- and ethano-bridged Tröger's base analogs with two peripheral fluorophores, i.e., anthracene, pyrene, and 9,9-dimethylfluorene units. These compounds, possessing two nitrogen stereogenic centers, exhibit good circularly polarized luminescence (CPL) dissymmetry factors (|glum| up to 1.2 × 10-3) and brightnesses (BCPL up to 26.3 M-1 cm-1), as well as excellent fluorescence quantum yields, demonstrating the Tröger´s base core to be a convenient scaffold to prepare CPL emitters upon functionalization with simple achiral fluorophores. Furthermore, the configurationally stable ethano-bridged Tröger's base analogs are employed to modulate their CPL response, generating a CPL switch through their protonation/deprotonation by consecutive additions of acid and base. The reversibility of the switching process is demonstrated for two cycles without altering the CPL performance of the molecule. It is believed that this straightforward and efficient approach to building CPL emitters employing the Tröger's base core could lead to its incorporation in CPL-based sensors and materials.

Controlled Synthesis of Dy/Cu Bimetallic Atoms for Efficient Artificial Photosynthesis

The birth of metal atom catalysts marked a new historical stage in the field of catalysis, allowing scientists to better understand the science of catalysis at the atomic level. On the basis of anchoring independent metal atoms, bimetal dysprosium-copper atoms are successfully anchored on graphdiyne (DyCu/GDY). Dy and Cu metal atoms are selectively anchored in triangular holes of GDY and stabilized by non-integer charge transfer and the confined space effect between the metals and GDY. The dynamic charge-transfer equilibrium caused by the inherent non-integer charge transfer between GDY and metal atoms produces sustained high activity, inducing a redistribution of surface charge. This result shows that the non-integer charge transfer strongly promotes the adsorption activation of CO2 and the desorption of the reaction intermediates, realizing the unpredictable selectivity and activity of CO2 conversion in the process of artificial photosynthesis, where the selectivity and yield of CO are 98% and 279 µmol gcat. -1 h-1, respectively.

Porous Organic Polymers for CO2 Capture and Catalytic Conversion

Overuse of fossil fuels and anthropogenic activities have led to excessive emissions of carbon dioxide, leading to global warming, and measures to reduce atmospheric carbon dioxide concentrations are needed to overcome this global challenge. Therefore, exploring an environmentally friendly strategy for capturing airborne CO2 and converting it into high-value-added chemicals offers a promising pathway toward "carbon neutrality". In recent years, porous organic polymers have attracted much attention for carbon capture and the catalytic conversion of carbon dioxide because of their high specific surface area, high chemical stability, nanoscale porosity, and structural versatility, which make them easy to functionalize. In this review, we introduce the preparation methods for various POPs, the types of POPs adsorbed during carbon dioxide capture, and the progress in the use of POPs for the photocatalytic and chemicatalytic conversion of carbon dioxide, with a special discussion on the influence of adsorption type on the efficiency of catalytic conversion. Finally, we propose a prospective direction for the subsequent development of this field.

CoII-organic 'soft' metallo-supramolecular polymer nanofibers for efficient photoreduction of CO2

Coordination-driven metallo-supramolecular polymers hold significant potential as highly efficient catalysts for photocatalytic CO2 reduction, owing to the covalent integration of the light harvesting unit, catalytic center and intrinsic hierarchical nanostructures. In this study, we present the synthesis, characterization, and gelation behaviour of a novel low molecular weight gelator (LMWG) integrating a benzo[1,2-b:4,5-b']dithiophene core with terpyridine (TPY) units via alkyl amide chains (TPY-BDT). The two TPY ends of the TPY-BDT unit efficiently chelate with metal ions, enabling the formation of a metallo-supramolecular polymer that brings together the catalytic center and a photosensitizer in close proximity, maximizing catalytic efficiency for CO2 reduction. The self-assembly of TPY-BDT with CoII ions yields a Co-TPY-BDT coordination polymer gel (CPG) with a 3D interconnected fibrous morphology, facilitating rapid electron transfer and efficient substrate diffusion. The Co-TPY-BDT CPG achieves an outstanding CO2 to CO conversion, producing 33.74 mmol g-1 of CO in 18 hours with ∼99% selectivity under visible light irradiation, using triethylamine (TEA) as a sacrificial electron donor. Remarkably, the Co-TPY-BDT CPG demonstrates significant catalytic activity even under low-concentration CO2 atmospheres (5% CO2, 95% Ar), producing 1.9 mmol g-1 of CO in 10 hours with a selectivity of 94.6%. Moreover, In situ diffuse reflectance Fourier transform (DRIFT) study, femtosecond transient absorption spectroscopy, and DFT calculations were employed to elucidate the CO2 to CO reaction mechanism.

Photoirradiation-enhanced behavior via morphological manipulation of CoFe2O4/g-C3N4 heterojunction for supercapacitor and CO2 reduction

Regulating the morphology of graphitic carbon nitride (g-C3N4, CN) and constructing CoFe2O4/g-C3N4 (CFO/CN) heterojunctions were adopted in the photocatalytic energy storage and photocatalytic CO2 reduction (PCR). CFO/CNS had outstanding light response ability, while CFO/CNT possessed excellent charge transfer ability. Consequently, CFO/CNT electrode exhibited the highest specific capacitance without light, CFO/CNS electrode showed the most obvious photo-enhanced capacitance behavior with an increase by 21.05 % under light. This was ascribed to the generation and separation of photo-generated carriers, promoting oxidation/reduction reactions. And in PCR, the electron consumption rates of four CFO/CN heterojunctions were CFO/CNT > CFO/BCN > CFO/MCN > CFO/CNS. CFO/CNT presented the highest photocatalytic activity, attributing to the strong redox ability and photo-enhanced electron transfer. This strategy of utilizing CFO/CN heterojunctions to construct photo-enhanced supercapacitor electrodes and photocatalytic CO2 reduction catalysts provided new ideas for energy conversion and storage.

Photoselectively modulating main products by changing the wavelength of visible light over D-π-A-D conjugated polymers

The diversity of catalytic products determines the difficulty of selective product modulation, which usually relies on adjusting the catalyst and reaction conditions to obtain different main products selectively. Herein, we synthesized D-π-A-D conjugated organic polymers (TH-COP) using cyclotriphosphonitrile, alkyne, 2H-benzimidazole, and sulfur units as electron donors, π bridges, electron acceptors, and electron donors, respectively. TH-COP exhibited excellent photoinduced carrier separation and redox ability under different visible light wavelengths, and the main products of its CO2 reduction are CH4 (1000.0 μmol g-1) and CO (837.0 μmol g-1) under 400-420 nm and 420-560 nm, respectively. In addition, TH-COP could completely convert phenylmethyl sulfide to methyl phenyl sulfone at 400-420 nm and diphenyl disulfide at 480-485 nm in yields up to 95 %. This study presents a novel strategy for the targeted fabrication of various main products using conjugated polymers by simply changing the wavelength range of visible light.

Microporous membrane with ionized sub-nanochannels enabling highly selective monovalent and divalent anion separation

Membranes tailored for selective ion transport represent a promising avenue toward enhancing sustainability across various fields including water treatment, resource recovery, and energy conversion and storage. While nanochannels formed by polymers of intrinsic microporosity (PIM) offer a compelling solution with their uniform and durable nanometer-sized pores, their effectiveness is hindered by limited interactions between ions and nanochannel. Herein, we introduce the randomly twisted V-shaped structure of Tröger's Base unit and quaternary ammonium groups to construct ionized sub-nanochannel with a window size of 5.89-6.54 Å between anion hydration and Stokes diameter, which enhanced the dehydrated monovalent ion transport. Combining the size sieving and electrostatic interaction effects, sub-nanochannel membranes achieved exceptional ion selectivity of 106 for Cl-/CO32- and 82 for Cl-/SO42-, significantly surpassing the state-of-the-art membranes. This work provides an efficient template for creating functionalized sub-nanometer channels in PIM membranes, and paves the way for the development of precise ion separation applications.

Efficient Charge Separation in Ag/PCN/UPDI Ternary Heterojunction for Optimized Photothermal-Photocatalytic Performance via Tandem Electric Fields

Charge separation driven by the internal electric field is a research hotspot in photocatalysis. However, it remains challenging to accurately control the electric field to continuously accelerate the charge transfer. Herein, a strategy of constructing a tandem electric field to continuously accelerate charge transfer in photocatalysts is proposed. The plasma electric field, interface electric field, and intramolecular electric field are integrated into the Ag/g-C3N4/urea perylene imide (Ag/PCN/UPDI) ternary heterojunction to achieve faster charge separation and longer carrier lifetime. The triple electric fields function as three accelerators on the charge transport path, promoting the separation of electron-hole pairs, accelerating charge transfer, enhancing light absorption, and increasing the concentration of energetic electrons on the catalyst. The H2 evolution rate of Ag/PCN/UPDI is 16.8 times higher than that of pristine PDI, while the degradation rate of oxytetracycline is increased by 4.5 times. This new strategy will provide a groundbreaking idea for the development of high-efficiency photocatalysts.

Hollow g-C3N4@Ag3PO4 Core-Shell Nanoreactor Loaded with Au Nanoparticles: Boosting Photothermal Catalysis in Confined Space

Low solar energy utilization efficiency and serious charge recombination remain major challenges for photocatalytic systems. Herein, a hollow core-shell Au/g-C3N4@Ag3PO4 photothermal nanoreactor is successfully prepared by a two-step deposition method. Benefit from efficient spectral utilization and fast charge separation induced by the unique hollow core-shell heterostructure, the H2 evolution rate of Au/g-C3N4@Ag3PO4 is 16.9 times that of the pristine g-C3N4, and the degradation efficiency of tetracycline is increased by 88.1%. The enhanced catalytic performance can be attributed to the ordered charge movement on the hollow core-shell structure and a local high-temperature environment, which effectively accelerates the carrier separation and chemical reaction kinetics. This work highlights the important role of the space confinement effect in photothermal catalysis and provides a promising strategy for the development of the next generation of highly efficient photothermal catalysts.

Synthetic Leaves Based on Crystalline Olefin-Linked Covalent Organic Frameworks for Efficient CO2 Photoreduction with Water

We report, for the first time, a new synthetic strategy for the preparation of crystalline two-dimensional olefin-linked covalent organic frameworks (COFs) based on aldol condensation between benzodifurandione and aromatic aldehydes. Olefin-linked COFs can be facilely crystallized through either a pyridine-promoted solvothermal process or a benzoic anhydride-mediated organic flux synthesis. The resultant COF leaf with high in-plane π-conjugation exhibits efficient visible-light-driven photoreduction of carbon dioxide (CO2) with water (H2O) in the absence of any photosensitizer, sacrificial agents, or cocatalysts. The production rate of carbon monoxide (CO) reaches as high as 158.1 μmol g-1 h-1 with near 100% CO selectivity, which is accompanied by the oxidation of H2O to oxygen. Both theoretical and experimental results confirm that the key lies in achieving exceptional photoinduced charge separation and low exciton binding. We anticipate that our findings will facilitate new possibilities for the development of semiconducting COFs with structural diversity and functional variability.

Conjugated Microporous Polymers for Catalytic CO2 Conversion

Rising carbon dioxide (CO2) levels in the atmosphere are recognized as a threat to atmospheric stability and life. Although this greenhouse gas is being produced on a large scale, there are solutions to reduction and indeed utilization of the gas. Many of these solutions involve costly or unstable technologies, such as air-sensitive metal-organic frameworks (MOFs) for CO2 capture or "non-green" systems such as amine scrubbing. Conjugated microporous polymers (CMPs) represent a simpler, cheaper, and greener solution to CO2 capture and utilization. They are often easy to synthesize at scale (a one pot reaction in many cases), chemically and thermally stable (especially in comparison with their MOF and covalent organic framework (COF) counterparts, owing to their amorphous nature), and, as a result, cheap to manufacture. Furthermore, their large surface areas, tunable porous frameworks and chemical structures mean they are reported as highly efficient CO2 capture motifs. In addition, they provide a dual pathway to utilize captured CO2 via chemical conversion or electrochemical reduction into industrially valuable products. Recent studies show that all these attractive properties can be realized in metal-free CMPs, presenting a truly green option. The promising results in these two fields of CMP applications are reviewed and explored here.

A Tröger's base-linked aluminium phthalocyanine polymer for discriminative electrochemical sensing of the antibiotic isoniazid

Isoniazid is a first-line drug used to treat tuberculosis. However, its excessive use can lead to serious adverse effects. Thus, strict monitoring of the isoniazid levels in medications and human systems is required. In this study, a new polymer (AlPc-TB POP) containing a metal phthalocyanine and Tröger's base was synthesized and explored as an electrocatalyst for the oxidation of isoniazid. The results indicated that the polymer is an excellent electron-transfer medium for isoniazid oxidation. The AlPc-TB POP-based sensor quantified isoniazid in the linear range of 0.1-130 μM, with a detection limit of 0.0185 μM. The response of the developed sensor to isoniazid was reproducible and stable. Furthermore, this method can accurately determine isoniazid levels by ignoring the influence of common interfering species in tablets and biological samples. This study contributes to the development of nitrogen-rich porous organic polymers and offers a novel strategy for addressing challenges in disease therapeutic efficacy and public safety monitoring.

Regulating π-Conjugation in sp2 -Carbon-Linked Covalent Organic Frameworks for Efficient Metal-Free CO2 Photoreduction with H2 O

The development of sp² -carbon-linked covalent organic frameworks (sp² c-COFs) as artificial photocatalysts for solar-driven conversion of CO₂ into chemical feedstock has captured growing attention, but catalytic performance has been significantly limited by their intrinsic organic linkages. Here, a simple, yet efficient approach is reported to improve the CO₂ photoreduction on metal-free sp² c-COFs by rationally regulating their intrinsic π-conjugation. The incorporation of ethynyl groups into conjugated skeletons affords a significant improvement in π-conjugation and facilitates the photogenerated charge separation and transfer, thereby boosting the CO₂ photoreduction in a solid-gas mode with only water vapor and CO₂ . The resultant CO production rate reaches as high as 382.0 µmol g^-1  h^-1 , ranking at the top among all additive-free CO₂ photoreduction catalysts. The simple modulation approach not only enables to achieve enhanced CO₂ reduction performance but also simultaneously gives a rise to extend the understanding of structure-property relationship and offer new possibilities for the development of new π-conjugated COF-based artificial photocatalysts.