Solution-processable polymers of intrinsic microporosity for gas-phase carbon dioxide photoreduction

Efficient unsymmetric disulfide formation by molecular-scale tailoring of ortho-polyquinone-based polymer photocatalyst

Disulfide bonds, especially unsymmetric disulfide bonds, have important applications in bioactivity and drug molecules, but the synthesis of unsymmetric disulfide bonds remains challenging due to efficiency and selectivity issues. Herein, this work utilizes anthraquinone (AQ) and cyclictriphosphonononitrile through a nucleophilic substitution reaction to synthesize an organic polymer (ANTH-AMI) that incorporates an ortho-polyquinone (o-polyquinone) redox center. The anthraquinone molecule functions as a redox center, capable of accepting photoinduced electrons and subsequently transferring them to initiate an electron-coupled hydrogenation reaction (AQ to AQH). Moreover, the proximity of the o-polyquinone redox sites facilitates the catalysis of unsymmetric disulfide bond formation. Consequently, the ANTH-AMI photocatalysts demonstrate exceptional yields (up to 82 %), substrate versatility, cycling stability, and scalable preparation in promoting unsymmetric coupling reactions of thiol. This work offers a solution for designing organic polymer photocatalysts with adjacent multiple redox centers for cross-coupling reactions.

Correlation between the Molecular Properties of Semiconducting Polymers of Intrinsic Microporosity and Their Photocatalytic Hydrogen Production

Increasing the interface area between organic semiconductor photocatalysts and electrolyte by fabricating nanoparticles has proven to be an effective strategy to increase photocatalytic hydrogen production activity. However, it remains unclear if increasing the internal interface by the introduction of porosity has as clear benefits for activity. To better inform future photocatalyst design, a series of polymers of intrinsic microporosity (PIMs) with the same conjugated backbone were synthesized as a platform to independently modulate the variables of porosity and relative hydrophilicity through the use of hydrophilic alcohol moieties protected by silyl ether protecting groups. When tested in the presence of ascorbic acid and photodeposited Pt, a strong correlation between the wettable porosity and photocatalytic activity was found, with the more wettable analogue of two polymers of almost the same surface area delivering 7.3 times greater activity, while controlling for other variables. Transient absorption spectroscopic (TAS) investigation showed efficient intrinsic charge generation within 10 ps in two of the porous polymers, even without the presence of ascorbic acid or Pt. Detectable hole polarons were found to be immediately extracted by added ascorbic acid, suggesting the generation of reactive charges at regions readily accessible to electrolyte in the porous structures. This study directs organic semiconductor photocatalysts design toward more hydrophilic functionality for addressing exciton and charge recombination bottlenecks and clearly demonstrates the advantages of wettable porosity as a design principle.

Rational Design of Conjugated Polymers for Photocatalytic CO2 Reduction: Towards Localized CO Production and Macrophage Polarization

Light presents substantial potential in disease treatment, where the development of efficient photocatalysts could enhance the utilization of photocatalytic systems in biomedicine. Here, we devised a novel approach to designing and synthesizing photocatalysts of conjugated polymers for photocatalytic CO2 reduction, relying on a multiple linear regression model built with theoretically calculated descriptors. We established a logarithmic relationship between molecular structure and CO yield and identified the poly(fluorene-co-thiophene) deviant (PFT) as the optimal one. PFT excited a CO regeneration ratio of 231 nmol h-1 in acetonitrile and 46 nmol h-1 in an aqueous solution with a reaction selectivity of 88%. Further advancements were made through the development of liposomes encapsulating PFT for targeted macrophage delivery. By distributing PFT on the liposome membranes, our constructed photocatalytic system efficiently generated CO in situ from surrounding CO2. This localized CO production served as an endogenous signaling molecule, promoting the desirable polarization of macrophages from the M1 to M2 phenotype. Consequently, the M2 cells reduced the secretion of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β). We also demonstrated the efficacy of our system in treating lipopolysaccharide-induced inflammation of cardiomyocytes under white light irradiation. Moreover, our research provides a comprehensive understanding of the intricate processes involved in CO2 reduction by a combination of theoretical calculations and experimental techniques including transient absorption, femtosecond ultrafast spectroscopy, and in situ infrared spectroscopy. These findings pave the way for further advancements of conjugated polymers and photocatalytic systems in biomedical investigation.

Synchrotron Radiation Based X-ray Absorption Spectroscopy: Fundamentals and Applications in Photocatalysis

Photocatalysis is one of the most promising green technologies to utilize solar energy for clean energy achievement and environmental governance. There is a knotty problem to rational designing high-performance photocatalyst, which largely depends on an in-depth insight into their structure-activity relationships and complex photocatalytic reaction mechanisms. Synchrotron radiation based X-ray absorption spectroscopy (XAS) is an important characterization method for photocatlayst to offer the element-specific key geometric and electronic structural information at the atomic level, on this basis, time-resolved XAS technique has a huge impact on mechanistic understanding of photochemical reaction owing to their powerful ability to probe, in real-time, the electronic and geometric structures evolution within photocatalysis reactions. This review will focus on the fundamentals of XAS and their applications in photocatalysis. The detailed applications obtained from XAS is described through the following aspects: 1) identifying local structure of photocatalyst; 2) uncovering in situ structure and chemical state evolution during photocatalysis; 3) revealing the photoexcited process. We will provide an in depth understanding on how the XAS method can guide the rational design of highly efficient photocatalyst. Finally, a systematic summary of XAS and related significance is made and the research perspectives are suggested.

Control of Properties through Hydrogen Bonding Interactions in Conjugated Polymers

Molecular design is crucial for endowing conjugated polymers (CPs) with unique properties and enhanced electronic performance. Introducing Hydrogen-bonding (H-bonding) into CPs has been a broadly exploited, yet still emerging strategy capable of tuning a range of properties encompassing solubility, crystallinity, electronic properties, solid-state morphology, and stability, as well as mechanical properties and self-healing properties. Different H-bonding groups can be utilized to tailor CPs properties based on the applications of interest. This review provides an overview of classes of H-bonding CPs (assorted by the different H-bond functional groups), the synthetic methods to introduce the corresponding H-bond functional groups and the impact of H-bonding in CPs on corresponding electronic and materials properties. Recent advances in addressing the trade-off between electronic performance and mechanical durability are also highlighted. Furthermore, insights into future directions and prospects for H-bonded CPs are discussed.