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The development of nonpyrolytic catalysts featuring precisely defined active sites represents an effective strategy for investigating the fundamental relationship between the catalytic activity of oxygen reduction reaction (ORR) catalysts and their local coordination environments. In this study, we have synthesized a series of model electrocatalysts with well‐defined CoN4 centers and nonplanar symmetric coordination structures. These catalysts were prepared by a sequential process involving the chelation of cobalt salts and 1,10‐phenanthroline‐based ligands with various substituent groups (phen(X), where X=OH, CH3, H, Br, Cl) onto covalent triazine frameworks (CTFs). By modulating the electron‐donating or electron‐withdrawing properties of the substituent groups on the phen‐based ligands, the electron density surrounding the CoN4 centers was effectively controlled. Our results demonstrated a direct correlation between the catalytic activity of the CoN4 centers and the electron‐donating ability of the substituent group on the phenanthroline ligands. Notably, the catalyst denoted as BCTF−Co‐phen(OH), featuring the electron‐donating OH group, exhibited the highest ORR catalytic activity. This custom‐crafted catalyst achieved a remarkable half‐wave potential of up to 0.80 V vs. RHE and an impressive turnover frequency (TOF) value of 47.4×10−3 Hz at 0.80 V vs. RHE in an alkaline environment. [ABSTRACT FROM AUTHOR]

The catalytic performance for electrocatalytic CO2 reduction reaction (CO2RR) depends on the binding strength of the reactants and intermediates. Covalent organic frameworks (COFs) have been adopted to catalyze CO2RR, and their binding abilities are tuned via constructing donor‐acceptor (DA) systems. However, most DA COFs have single donor and acceptor units, which caused wide‐range but lacking accuracy in modulating the binding strength of intermediates. More elaborate regulation of the interactions with intermediates are necessary and challenge to construct high‐efficiency catalysts. Herein, the three‐component COF with D‐A‐A units was first constructed by introducing electron‐rich diarylamine unit, electron‐deficient benzothiazole and Co‐porphyrin units. Compared with two‐component COFs, the designed COF exhibit elevated electronic conductivity, enhanced reducibility, high efficiency charge transfer, further improving the electrocatalytic CO2RR performance with the faradic efficiency of 97.2 % at −0.8 V and high activity with the partial current density of 27.85 mA cm−2 at −1.0 V which exceed other two‐component COFs. Theoretical calculations demonstrate that catalytic sites in three‐component COF have suitable binding ability of the intermediates, which are benefit for formation of *COOH and desorption of *CO. This work offers valuable insights for the advancement of multi‐component COFs, enabling modulated charge transfer to improve the CO2RR activity. [ABSTRACT FROM AUTHOR]

Fullerene exhibits a wealth of interesting characteristics owing to its unique π‐electron configuration. The structure and properties of fullerene can be manipulated by introducing chemical groups to the carbon–carbon bonds via organic reactions, extending its application field. The Diels–Alder (DA) cycloaddition reaction is commonly used to decorate the carbon cage of fullerene. Furthermore, atoms, ions, clusters, and molecules can be inserted into the hollow carbon cage of a fullerene, thereby changing the electron transfer process within the fullerene cage and thus the reactivity of the as well as the regioselectivity of the DA cycloaddition reaction. Computer‐based theoretical modeling is an essential tool for studying chemistry. Herein, we provide a brief review of theoretical investigations into the cycloaddition mechanism of two most common fullerenes (C60 and C70), especially in terms of the effects of encapsulated chemical species based on the distortion–interaction model. We hope that the current mini review will provide a useful and interesting resource for researchers working on—or simply being interested in—the in silico investigation of fullerenes and their DA‐based modification. [ABSTRACT FROM AUTHOR]

Vinylene‐linked covalent organic frameworks (COFs) have attracted enormous attention for photocatalytic H2 evolution from water because of their fully conjugated structures, high chemical stabilities, and enhanced charge‐carrier mobilities. In this work, two novel vinylene‐linked COFs with tuned cyano contents were successfully synthesized and then employed as photocatalysts for H2 generation. Notably, the photocatalytic H2 production rate of the COF with the higher cyano content reached 73 μmol h−1 under visible light irradiation, which is 2.4 times higher than that with the lower content (30 μmol h−1). Both the experimental and computational results demonstrated that the rational design incorporating cyano groups into COF skeletons could precisely tune the corresponding energy levels, expand the visible‐light absorption, and improve the photoinduced charge separation. This work not only provides a simple method for modulating the photocatalytic activities of COFs at the molecular level, but also affords interesting insights into the relationship between their structures and photocatalytic performance. [ABSTRACT FROM AUTHOR]

Donor–acceptor linear conjugated polyelectrolytes (D–A linear CPEs) have been considered as a type of potential organic photocatalyst for photocatalytic hydrogen evolution. However, most of the organic photocatalysts suffer from an unfavorable hydrogen evolution rate, primarily originating from unsuitable photoelectric properties for photocatalysis. The quest for a universal and easy method to turn the photoelectric characteristics of organic photocatalysts is significant for photocatalytic hydrogen evolution. Herein, we present two series of D–A linear CPEs (PFBBr and PBBBr series). Compared to the PFBBr series polyelectrolytes, the PBBBr series shows obvious extended absorption spectra. Moreover, we employed a facile substituent optimization strategy to fine-turn the photoelectric properties and realized an optimized photocatalytic hydrogen evolution efficiency. Compared to the methoxy group, chlorine atom modified PBBBr, i.e. PBBBr-Cl, achieved a high hydrogen evolution rate of over 1.90 mmol g−1 h−1 (4.3 times than that of PBBBr-OMe and 8.5 times than that of PFBBr-OMe). The CPEs with strong electron withdrawing substituents (–F and –Cl) present a reduced exciton binding energy, a smaller absolute value of hydrogen adsorption energy, and an enhanced molecular dipole. Moreover, efficient charge transfer to Pt cocatalysts was observed in –F/–Cl modified CPEs through femtosecond transient absorption spectroscopy. Our results reveal the great potential of substituent optimization in high-performance organic photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

Two‐dimensional covalent organic frameworks (2D COFs) are often employed for electrocatalytic systems because of their structural diversity. However, the efficiency of atom utilization is still in need of improvement, because the catalytic centers are located in the basal layers and it is difficult for the electrolytes to access them. Herein, we demonstrate the use of 1D COFs for the 2e− oxygen reduction reaction (ORR). The use of different four‐connectivity blocks resulted in the prepared 1D COFs displaying good crystallinity, high surface areas, and excellent chemical stability. The more exposed catalytic sites resulted in the 1D COFs showing large electrochemically active surface areas, 4.8‐fold of that of a control 2D COF, and thus enabled catalysis of the ORR with a higher H2O2 selectivity of 85.8 % and activity, with a TOF value of 0.051 s−1 at 0.2 V, than a 2D COF (72.9 % and 0.032 s−1). This work paves the way for the development of COFs with low dimensions for electrocatalysis. [ABSTRACT FROM AUTHOR]

To achieve high-efficiency catalysts for CO2 reduction reaction, various catalytic metal centres and linker molecules have been assembled into covalent organic frameworks. The amine-linkages enhance the binding ability of CO2 molecules, and the ionic frameworks enable to improve the electronic conductivity and the charge transfer along the frameworks. However, directly synthesis of covalent organic frameworks with amine-linkages and ionic frameworks is hardly achieved due to the electrostatic repulsion and predicament for the strength of the linkage. Herein, we demonstrate covalent organic frameworks for CO2 reduction reaction by modulating the linkers and linkages of the template covalent organic framework to build the correlation between the catalytic performance and the structures of covalent organic frameworks. Through the double modifications, the CO2 binding ability and the electronic states are well tuned, resulting in controllable activity and selectivity for CO2 reduction reaction. Notably, the dual-functional covalent organic framework achieves high selectivity with a maximum CO Faradaic efficiency of 97.32% and the turnover frequencies value of 9922.68 h−1, which are higher than those of the base covalent organic framework and the single-modified covalent organic frameworks. Moreover, the theoretical calculations further reveal that the higher activity is attributed to the easier formation of immediate *CO from COOH*. This study provides insights into developing covalent organic frameworks for CO2 reduction reaction. Covalent organic frameworks constructed with ionic skeletons and C-N linkages by multilevel post-synthetic modification. These frameworks achieved high activity and stability for electrocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

The effective detection of environmental pollutants is very important to the sustainable development of human health and the environment. A luminescent Cd(II) coordination complex, {[Cd(dbtdb)(1,2,4-H3btc)]·0.5H2O}n (1) (dbtdb = 1-(2,3,5,6-tetramethyl-4-((2-(thiazol-4-yl)-2H-benzo[d]imidazol-3(3aH)-yl)methyl)benzyl)-2,7a-dihydro-2-(thiazol-4-yl)-1H-benzo[d]imidazole, 1,2,4-H3btc = 1,2,4-benzenetricarboxylic acid), was obtained by hydrothermal reactions. Complex 1 has a chain structure decorated with uncoordinated Lewis basic O and S donors and provides good sensing of Fe3+, Cr2O72−, and p-nitrophenol with fluorescence quenching through an energy transfer process. The calculated binding constants were 3.3 × 103 mol−1 for Fe3+, 2.36 × 104 mol−1 for Cr2O72−, and 9.3 × 103 mol−1 for p-nitrophenol, respectively. These results show that 1 is a rare multiresponsive sensory material for efficient detection of Fe3+, Cr2O72−, and p-nitrophenol. [ABSTRACT FROM AUTHOR]

A porphyrin-based conjugated organic polymer (COP) was constructed from 5,10,15,20-tetrakis(4-bromophenyl)porphyrin copper (CuTBPP) and 5,5′-bis-ethynyl-2,2′-bipyridine (BPY) via Sonogashira coupling. Its complex Co/CuTBPP–BPY–COP (with dual metal sites composed of copper porphyrin and a cobalt BPY unit) was prepared by coordination with Co2+. All of the prepared CuTBPP–BPY–COP and Co/CuTBPP–BPY–COP compounds exhibited excellent photocatalytic performance toward CO2 reduction under visible-light irradiation without another sacrificial reagent but only H2O. Co/CuTBPP–BPY–COP (dual metal sites) exhibited better photocatalytic activity than CuTBPP–BPY–COP (a single metal site). Co/CuTBPP–BPY–COP retained a higher photocatalysis capacity for CO2 reduction after 10 consecutive cycles. The total quantity of CO product was 263.2 μmol g−1 after 10 h of irradiation. Theoretical studies indicate that introducing Co metal centers and nitro groups are more favorable for the photoreduction catalysis of CO2 compared with that using CuTBPP–BPY–COP. [ABSTRACT FROM AUTHOR]