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An interlocked covalent organic molecular cage with a trigonal-prismatic structure based on anthracene units and imine bonds was synthesized by a template-free and one-pot reaction in a relatively good yield. By comparing the single-crystal structures of the interlocked cage and two additional monomeric cages as reference compounds, a cause of weak supramolecular interaction-induced synthesis was proposed; π···π interactions induce the triphenylbenzene units as the core and anthracenes as side parts close to each other, which provides a possibility of the preorganization for the formation of the interlocked structure.

Metal-halide layered perovskites, self-assembled quantum wells with alternating insulating interlayer organic cations, and conductive perovskite layers boost the incorporation of multiple functionalities into a single-phase material. Optoelectronic performances in layered perovskites are more sensitive to crystallinity than their 3D counterparts due to the traps and insulating barriers introduced by interlayer cations. Here, we combine the capillary-bridge lithography method for the fabrication of single-crystalline nanowire arrays with strongly interacted layered perovskites for the enhancement of crystallinity and crystallographic orientation purity. Due to regulated nucleation and growth of layered perovskites in capillary bridges and the sulfur-sulfur interaction between interlayer cations, nanowires with pure (101) orientation are realized for underpinning insulating crystal interiors and photoconductive layer edges. Based on these nanowires, ultrasensitive photodetectors are reached with an ultralow dark current of below 10 -12 A, an average responsivity of 7.3 × 10 3 A W -1 , an average specific detectivity of 3.9 × 10 15 Jones, and a 3 dB bandwidth of 10.3 kHz.

Developing visible-light-active porous organic polymers with high photocatalytic efficiency is highly desirable. Here, two triazine-based conjugated microporous polymers were synthesized. The structures were controllably adjusted to explore the structure-photocatalytic activity relationship. T-CMP-1 containing more triazine units exhibited a hydrogen evolution rate of 3214.3 μmol h -1 g -1 , much higher than that of T-CMP-2 (242.1 μmol h -1 g -1 ). The increasing contents of triazine units bring better hydrogen evolution efficiency., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

A two-dimensional polymer (2DP) single crystal ( T-2DP ) with submillimeter size was synthesized by single-crystal to single-crystal transformation based on photochemical [2 + 2]-cycloaddition. A successful conversion from monomer to polymer was achieved in the single-crystal state. The structure information with an atomic resolution of both the monomer and 2DP was given through single-crystal X-ray diffraction. By simply treated with trifluoroacetic acid (TFA) under mild conditions, an unprecedented efficiency of exfoliation was achieved. The triazine core in T-2DP could be protonated by TFA, which resulted in a solution-like sample with >60% of monolayers. The size of the exfoliated monolayer reaches to several hundreds of μm 2 . This is another precious example of 2DP single crystal with nearly perfect structure and large enough size. The successful preparation of the highly desirable 2DP "solution" for a long time containing large sized and large amount of 2DP monolayers may open up new prospects for the basic properties study and the applications of 2DPs.

The efficient conversion of CO 2 to chemical fuels driven by solar energy is still a challenging research area in photosynthesis, in which the conversion efficiency greatly relies on photocatalytic coenzyme NADH regeneration. Herein, a photocatalyst/biocatalyst synergetic system based on a conjugated microporous polymer (CMP) was prepared for sustainable and highly selective photocatalytic reduction of CO 2 to methanol. Two thiazolo[5,4- d ]thiazole-linked CMPs ( TZTZ-TA and TZTZ-TP ) were designed and synthesized as photocatalysts. Slight skeleton modification led to a great difference in their photocatalytic performance. Triazine-based TZTZ-TA exhibited an unprecedentedly high NADH regeneration efficiency of 82.0% yield within 5 min. Furthermore, the in situ photocatalytic NADH regeneration system could integrate with three consecutive enzymes for efficient conversion of CO 2 into methanol. This CMP-enzyme hybrid system provides a new avenue for accomplishing the liquid sunshine from CO 2 .

Covalent organic frameworks (COFs) with improved stability and extended π-conjugation structure are highly desirable. Here, two imine-linked COFs were converted into ultrastable and π-conjugated fused-aromatic thieno[3,2- c ]pyridine-linked COFs ( B-COF-2 and T-COF-2 ). The successful conversion was confirmed by infrared and solid-state 13 C NMR spectroscopies. Furthermore, the structures of thieno[3,2- c ]pyridine-linked COFs were evaluated by TEM and PXRD. It is noted that a slight difference in the structure leads to totally different photoactivity. The fully π-conjugated T-COF-2 containing triazine as the core exhibited an excellent photocatalytic NADH regeneration yield of 74% in 10 min.

Highly selective removal of N 2 from unconventional natural gas is considered as a viable way to increase the heat value of CH 4 and reduce the greenhouse effect caused by the direct emission of CH 4 /N 2 mixture. In this work, a three-dimensional Cu-MOF with two different types of micropores was synthesized, exhibiting a high selectivity for CH 4 /N 2 (10.00-12.67) and the highest sorbent selection parameter value (65.73) among the reported materials. The CH 4 molecule interacts with the framework to form multiple van der Waals interactions both in hydrophilic and hydrophobic pores, indicated by density functional theory calculations to gain a deep insight into the adsorption binding sites. In contrast, the weak polarity feature of the hydrophobic pore and the occupied open-metal sites in the hydrophilic pore result in a very low adsorption uptake of N 2 . The excellent separation performance combining the good stability and regenerability guarantees this Cu-MOF to be a promising adsorbent for an efficient separation of the CH 4 /N 2 mixture., Competing Interests: The authors declare no competing financial interest.

Here we reported the doping of graphdiyne in P3CT-K in MAPbI 3 perovskite solar cells as hole-transport materials. The doping could improve the surface wettability of P3CT-K, and the resulting perovskite morphology was improved with homogeneous coverage and reduced grain boundaries. Simultaneously, it increased the hole-extraction mobility and reduced the recombination as well as improved the performance of devices. Therefore, a high efficiency of 19.5% was achieved based on improved short-circuit current and fill factor. In addition, hysteresis of the J- V curve was also obviously reduced. This work paves the way for the development of highly efficient perovskite solar cells.

The objective of this Account is to summarize the first five years of anion-π catalysis. The general idea of anion-π catalysis is to stabilize anionic transition states on aromatic surfaces. This is complementary to the stabilization of cationic transition states on aromatic surfaces, a mode of action that occurs in nature and is increasingly used in chemistry. Anion-π catalysis, however, rarely occurs in nature and has been unexplored in chemistry. Probably because the attraction of anions to π surfaces as such is counterintuitive, anion-π interactions in general are much younger than cation-π interactions and remain under-recognized until today. Anion-π catalysis has emerged from early findings that anion-π interactions can mediate the transport of anions across lipid bilayer membranes. With this evidence for stabilization in the ground state secured, there was no reason to believe that anion-π interactions could not also stabilize anionic transition states. As an attractive reaction to develop anion-π catalysis, the addition of malonic acid half thioesters to enolate acceptors was selected. This choice was also made because without enzymes decarboxylation is preferred and anion-π interactions promised to catalyze selectively the disfavored but relevant enolate addition. Concerning anion-π catalysts, we started with naphthalene diimides (NDIs) because their intrinsic quadrupole moment is highly positive. The NDI scaffold was used to address questions such as the positioning of substrates on the catalytic π surface or the dependence of activity on the π acidity of this π surface. With the basics in place, the next milestone was the creation of anion-π enzymes, that is, enzymes that operate with an interaction rarely used in biology, at least on intrinsically π-acidic or highly polarizable aromatic amino-acid side chains. Electric-field-assisted anion-π catalysis addresses topics such as heterogeneous catalysis on electrodes and remote control of activity by voltage. On π-stacked foldamers, anion-(π) n -π catalysis was discovered. Fullerenes emerged as the scaffold of choice to explore contributions from polarizability. On fullerenes, anionic transition states are stabilized by large macrodipoles that appear only in response to their presence. With this growing collection of anion-π catalysts, several reactions beyond enolate addition have been explored so far. Initial efforts focused on asymmetric anion-π catalysis. Increasing enantioselectivity with increasing π acidity of the active π surface has been exemplified for enamine and iminium chemistry and for anion-π transaminase mimics. However, the delocalized nature of anion-π interactions calls for the stabilization of charge displacements over longer distances. The first step in this direction was the formation of cyclohexane rings with five stereogenic centers from achiral acyclic substrates on π-acidic surfaces. Moreover, the intrinsically disfavored exo transition state of anionic Diels-Alder reactions is stabilized selectively on π-acidic surfaces; endo products and otherwise preferred Michael addition products are completely suppressed. Taken together, we hope that these results on catalyst design and reaction scope will establish anion-π catalysis as a general principle in catalysis in the broadest sense.

The molecular structure of cathode interface modification materials can affect the surface morphology of the active layer and key electron transfer processes occurring at the interface of polymer solar cells in inverted structures mostly due to the change of molecular configuration. To investigate the effects of spatial configuration of the cathode interfacial modification layer on polymer solar cells device performances, we introduced two novel organic ionic salts (linear NS2 and three-dimensional (3D) NS4) combined with the ZnO film to fabricate highly efficient inverted solar cells. Both organic ionic salts successfully decreased the surface traps of the ZnO film and made its work function more compatible. Especially NS4 in three-dimensional configuration increased the electron mobility and extraction efficiency of the interfacial film, leading to a significant improvement of device performance. Power conversion efficiency (PCE) of 10.09% based on NS4 was achieved. Moreover, 3D interfacial modification could retain about 92% of its initial PCE over 160 days. It is proposed that 3D interfacial modification retards the element penetration-induced degradation without impeding the electron transfer from the active layer to the ZnO film, which significantly improves device stability. This indicates that inserting three-dimensional organic ionic salt is an efficient strategy to enhance device performance.

Developing earth-abundant, highly active, and robust electrocatalysts capable of both oxygen and hydrogen evolution reactions is crucial for the commercial success of renewable energy technologies. Here we demonstrate a facile and universal strategy for fabricating transition metal (TM) sulfides by controlling the atomic ratio of TM precursors for water splitting in basic media. Density functional theory calculations reveal that the incorporation of Fe/Co can significantly improve the catalytic performance. The optimal material exhibits extremely small overpotentials of 208 mV for oxygen evolution and 68 mV for hydrogen evolution at 10 mA cm -2 with robust long-term stability. The optimized material was used as bifunctional electrodes for overall water splitting, which delivers 10 mA cm -2 at a very low cell voltage of 1.44 V with robust stability over 80 h at 100 mA cm -2 without degradation, much better than the combination of Pt and RuO 2 as benchmark catalysts. The excellent water-splitting performance sheds light on the promising potential of such sulfides as high activity and robust stable electrodes.

We explored the interfacial synthesis of 2D N-graphdiyne films at the gas/liquid and liquid/liquid interfaces. Triazine- or pyrazine-based monomers containing ethynyl group were polymerized through the Glaser coupling reactions at interfaces. Several layered, highly ordered and conjugated 2D N-graphdiyne were obtained. Their structures were characterized by TEM, SEM, AFM, XPS, and Raman spectra. Thin films with minimum thickness of 4 nm could be prepared.

This work proves the existence and chemical addressability of defined edge groups of a 2D polymer. Pseudohexagonally prismatic single crystals consisting of layered stacks of a 2D polymer are used. They should expose anthracene-based edge groups at the six (100) but not at the two pseudohexagonal (001) and (001̅) faces. The crystals are reacted with the isotopically enriched dienophiles maleic anhydride and a C18-alkyl chain-modified maleimide. In both cases the corresponding Diels-Alder adducts between these reagents and the edge groups are formed as confirmed by solid state NMR spectroscopy. The same applies to a maleimide derivative carrying a BODIPY dye which was chosen for its fluorescence to be out of the range of the self-fluorescence of the 2D polymer crystals stemming from contained template molecules. If the crystals are excited at λ = 633 nm, their (100) faces and thus their rims fluoresce brightly, while the pseudohexagonal faces remain silent. This is visible when the crystals lie on a pseudohexagonal face. Lambda-mode laser scanning microscopy confirms this fluorescence to originate from the BODIPY dye. Micromechanical exfoliation of the dye-modified crystals results in thinner sheet packages which still exhibit BODIPY fluorescence right at the rim of these packages. This work establishes the chemical nature of the edge groups of a 2D polymer and is also the first implementation of an edge group modification similar to end group modifications of linear polymers.

This Perspective elaborates on the currently unfolding interest in integrating unorthodox non-covalent interactions into functional systems. Initial emphasis is on anion-π interactions at work, particularly in catalysis. Recent highlights are described in comparison to a coinciding renaissance of the more conventional, charge-inverted cation-π catalysis. Progress with these complementary aromatic systems is then compared to recent efforts to integrate halogen and chalcogen bonds, the unorthodox counterparts of hydrogen bonds, into functional systems. General focus is on catalysis, pertinent examples on self-assembly, transport, sensing, and templation are covered as well.

Here we provide experimental evidence for anion-π catalysis of enamine chemistry and for asymmetric anion-π catalysis. A proline for enamine formation on one side and a glutamic acid for nitronate protonation on the other side are placed to make the enamine addition to nitroolefins occur on the aromatic surface of π-acidic naphthalenediimides. With increasing π acidity of the formally trifunctional catalysts, rate and enantioselectivity of the reaction increase. Mismatched and more flexible controls reveal that the importance of rigidified, precisely sculpted architectures increases with increasing π acidity as well. The absolute configuration of stereogenic sulfoxide acceptors at the edge of the π-acidic surface has a profound influence on asymmetric anion-π catalysis and, if perfectly matched, affords the highest enantio- and diastereoselectivity.

The introduction of new noncovalent interactions to build functional systems is of fundamental importance. We here report experimental and theoretical evidence that anion-π interactions can contribute to catalysis. The Kemp elimination is used as a classical tool to discover conceptually innovative catalysts for reactions with anionic transition states. For anion-π catalysis, a carboxylate base and a solubilizer are covalently attached to the π-acidic surface of naphthalenediimides. On these π-acidic surfaces, transition-state stabilizations up to ΔΔGTS = 31.8 ± 0.4 kJ mol(-1) are found. This value corresponds to a transition-state recognition of KTS = 2.7 ± 0.5 μM and a catalytic proficiency of 3.8 × 10(5) M(-1). Significantly increasing transition-state stabilization with increasing π-acidity of the catalyst, observed for two separate series, demonstrates the existence of "anion-π catalysis." In sharp contrast, increasing π-acidity of the best naphthalenediimide catalysts does not influence the more than 12 000-times weaker substrate recognition (KM = 34.5 ± 1.6 μM). Together with the disappearance of Michaelis-Menten kinetics on the expanded π-surfaces of perylenediimides, this finding supports that contributions from π-π interactions are not very important for anion-π catalysis. The linker between the π-acidic surface and the carboxylate base strongly influences activity. Insufficient length and flexibility cause incompatibility with saturation kinetics. Moreover, preorganizing linkers do not improve catalysis much, suggesting that the ideal positioning of the carboxylate base on the π-acidic surface is achieved by intramolecular anion-π interactions rather than by an optimized structure of the linker. Computational simulations are in excellent agreement with experimental results. They confirm, inter alia, that the stabilization of the anionic transition states (but not the neutral ground states) increases with the π-acidity of the catalysts, i.e., the existence of anion-π catalysis. Preliminary results on the general significance of anion-π catalysis beyond the Kemp elimination are briefly discussed.

A pH-controlled fluorescence switch based on a core-substituted naphthalenediimide compound (NDI-DBU) was constructed. The novel pentacyclic compound (NDI-DBU) was derived from naphthalenediimide (NDI) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in only one synthetic operation, catalysized by CuI.

Three novel gold nanoparticle (AuNPs) composites protected by perylene bisimide derivatives have been designed and synthesized. Thanks to the rational molecular design, AuNPs capped by N,N'-2,6-bis(4-aminomethylpyridine)-1,6,7,13-tert-[4-(hydroxymethyl)phenoxy-5-(1,2-dithiolan-3-yl)pentanoate]-3,4,9,10- tetracarboxylic acid bisimide (8SP-AuNPs) exhibited unusual enhancement in fluorescence intensity, while the other two nanoparticle composites showed slight enhancement or quench in emission spectra. The structural effect of ligands on aggregation enhanced emission had been studied, and temperature dependence experiments had been conducted. Deductive explanation had been made to elucidate the special spectral behavior of 8SP-AuNPs led by restricted motion of perylene chromophores in the packed nanoclusters.