QAAR exploration on pesticides with high solubility:An investigation on sulfonylurea herbicide dimers formed through π–π stacking interactions

Bioactive compounds could form aggregates that influence the bio-interactive processes. In this letter,based on p–p stacking models, quantitative aggregation–activity relationship(QAAR) studies were carried out on a series of sulfonylurea herbicides with good solubility. Four QAAR/QSAR models were constructed, which indicated that the bioactivity may strongly depend on both the characters of the dimeric aggregates and the monomer. The QAAR approach based on dimer-aggregates was also applicable for the highly water-soluble sulfonylurea herbicides that can form p–p stacking interactions.It was expected that the QAAR studies based on molecular aggregation state would be applied to other pesticide systems.     

Perfectly Encoding π-Conjugated Anions in the RE5(C3N3O3)(OH)12 (RE=Y,Yb, Lu) Family with Strong Second Harmonic Generation Response and Balanced Birefringence

Nonlinear optical (NLO) crystal, which simultaneously exhibits strong second-harmonic-generation (SHG) response and desired optical anisotropy, is a core optical material accessible to the modern optoelectronics. Accompanied by strong SHG effect in a NLO crystal, a contradictory problem of overlarge birefringence is ignored, leading to low frequency doubling efficiency and poor beam quality. Herein, a series of rare earth cyanurates RE₅(C₃N₃O₃)(OH)₁₂ (RE=Y, Yb, Lu) were successfully characterized by 3D electron diffraction technique. Based on a “three birds with one stone” strategy, they enable the simultaneous fulfillment of strong SHG responses (2.5–4.2× KH₂PO₄), short UV cutoff (ca. 220 nm) and applicable birefringence (ca. 0.15 at 800 nm) by the introduction of rare earth coordination control of π-conjugated (C₃N₃O₃)³⁻ anions. These findings provide high-performance short-wavelength NLO materials and highlight the exploration of cyanurates as a new research area.     

Opportunities and challenges in photochemical activation of π-bond system using common transition-metal-catalyzes as a seminal photosensitizer

The volatility of noble metals prices, globally increasing demands, and its limited resources drive chemists to find alternatives in the place of expensive transition metal catalysts. So, this is a time for the scientific community to find alternative sources to replace Nobel metals, and it is making genuine changes in developing sustainable synthetic methods. Photoexcited transition-metal catalysis is revitalizing the research area for functionalizing diverse π-bond systems. The massive progression of the two conventional photochemical reactivity modes, photoredox catalysis, and synergetic photocatalyst/transition-metal catalysis, has fueled the search for a next-level mechanistic paradigm visible-light initiated excited-state transition-metal catalysis (Cu, Pd, Fe, Au, Co, Ni, W, and Mn), which can be deployed to harvest light energy and convert it into chemical energy in a single catalytic cycle. This review summarizes early examples of the visible-light-induced photocatalytic activities of conventional transition metals employed in C-H activation, π-bond functionalization, and annulation reactions of unsaturated compounds, and excluding the commonly used expensive photocatalysts (i.e., Ir-, and Ru-based pyridyl complexes). Unlike the other two classical photochemical approaches, the discrete inner-sphere mechanism associated with photoexcited transition metals facilitates reactive substrate-metal-complex interactions. It enables the direct involvement of excited-state catalysts in bond-forming or-breaking processes.     

Enhanced Energy Transfer in A π-Conjugated Covalent Organic Framework Facilitates Excited-State Nickel Catalysis

Covalent organic frameworks (COFs) have received broad interest owing to their permanent porosity, high stability, and tunable functionalities. COFs with long-range π-conjugation and photosensitizing building blocks have been explored for sustainable photocatalysis. Herein, we report the first example of COF-based energy transfer Ni catalysis. A pyrene-based COF with sp² carbon-conjugation was synthesized and used to coordinate Ni^II centers through bipyridine moieties. Under light irradiation, enhanced energy transfer in the COF facilitated the excitation of Ni centers to catalyze borylation and trifluoromethylation reactions of aryl halides. The COF showed two orders of magnitude higher efficiency in these reactions than its homogeneous control and could be recovered and reused without significant loss of catalytic activity.     

Tetranuclear CuII Cluster as the Ten Node Building Unit for the Construction of a Metal–Organic Framework for Efficient C2H2/CO2 Separation

Rational design of high nuclear copper cluster-based metal–organic frameworks has not been established yet. Herein, we report a novel MOF ( FJU-112 ) with the ten-connected tetranuclear copper cluster [Cu₄(PO₃)₂(μ₂-H₂O)₂(CO₂)₄] as the node which was capped by the deprotonated organic ligand of H₄L (3,5-Dicarboxyphenylphosphonic acid). With BPE (1,2-Bis(4-pyridyl)ethane) as the pore partitioner, the pore spaces in the structure of FJU-112 were divided into several smaller cages and smaller windows for efficient gas adsorption and separation. FJU-112 exhibits a high separation performance for the C₂H₂/CO₂ separation, which were established by the temperature-dependent sorption isotherms and further confirmed by the lab-scale dynamic breakthrough experiments. The grand canonical Monte Carlo simulations (GCMC) studies show that its high C₂H₂/CO₂ separation performance is contributed to the strong π-complexation interactions between the C₂H₂ molecules and framework pore surfaces, leading to its more C₂H₂ uptakes over CO₂ molecules.     

σ-Cyclopropyl to π-Allyl Rearrangement at AuIII

The possibility for Au^III σ-cyclopropyl complexes to undergo ring-opening and give π-allyl complexes was interrogated. The transformation was first evidenced within (P,C)-cyclometalated complexes, it occurs within hours at −50 °C. It was then generalized to other ancillary ligands. With (N,C)-cyclometalated complexes, the rearrangement occurs at room temperature while it proceeds already at −80 °C with a dicationic (P,N)-chelated complex. Density Functional Theory (DFT) calculations shed light on the mechanism of the transformation, a disrotatory electrocyclic ring-opening. Intrinsic Bond Orbital (IBO) analysis along the reaction profile shows the cleavage of the distal σ(CC) bond to give a π-bonded allyl moiety. Careful inspection of the structure and bonding of cationic σ-cyclopropyl complexes support the possible existence of C−C agostic interactions at Au^III.     

On-Demand Control of Short-Wave Infrared Light Transparency Based on Stimuli-Responsive Association of Tetrathiafulvalene Radical Cations

The light-transmissive properties of a solid-state tetrathiafulvalene radical cation-bis(trifluoromethanesulfonyl)imide, 1-C₅⋅⁺ ⋅ NTf₂⁻, underwent instantaneous changes in the short-wave infrared (SWIR) region (1000–2500 nm) upon exposure to solvent vapor or the application of mechanostress at room temperature. The initial solid state of 1-C₅⋅⁺ ⋅ NTf₂⁻ exhibited strong absorption in the near-infrared (NIR; 700–1000 nm) and SWIR regions, whereas the absorption in the SWIR region was significantly diminished in the stimulated state induced by dichloromethane vapor. Upon cessation of vapor stimulation, the solid state spontaneously and promptly reverted to its original state, characterized by absorption bands in the NIR/SWIR region. Moreover, the SWIR absorption was absent upon the application of mechanical stress using a steel spatula. The reversal was fast and occurred within 10 s. These changes were visualized using a SWIR imaging camera under 1450-nm light irradiation. Experimental investigations demonstrated that the transparency to the SWIR light in the solid states was modulated through significant structural transformations of the associated radical cations, with transitions between columnar and isolated π-dimer structures under ambient and stimulated conditions, respectively.     

Electrically Conductive π-Intercalated Graphitic Metal-Organic Framework Containing Alternate π-Donor/Acceptor Stacks

Two-dimensional graphitic metal–organic frameworks (GMOF) often display impressive electrical conductivity chiefly due to efficient through-bond in-plane charge transport, however, less efficient out-of-plane conduction across the stacked layers creates large disparity between two orthogonal conduction pathways and dampens their bulk conductivity. To address this issue and engineer higher bulk conductivity in 2D GMOFs, we have constructed via an elegant bottom-up method the first π-intercalated GMOF (iGMOF1) featuring built-in alternate π-donor/acceptor (π-D/A) stacks of Cu^II-coordinated electron-rich hexaaminotriphenylene (HATP) ligands and non-coordinatively intercalated π-acidic hexacyano-triphenylene (HCTP) molecules, which facilitated out-of-plane charge transport while the hexagonal Cu₃(HATP)₂ scaffold maintained in-plane conduction. As a result, iGMOF1 attained an order of magnitude higher bulk electrical conductivity and much smaller activation energy than Cu₃(HATP)₂ (σ=25 vs. 2 S m⁻¹, E_a=36 vs. 65 meV), demostrating that simultaneous in-plane (through-bond) and out-of-plane (through πD/A stacks) charge transport can generate higher electrical conductivity in novel iGMOFs.     

A Highly Water-Soluble Aggregation-Induced Emission Luminogen with Anion-π+ Interactions for Targeted NIR Imaging of Cancer Cells and Type I Photodynamic Therapy

The low oxygen dependence of type I photosensitizers (PSs) has made them a popular choice for treating solid tumors. However, the drawbacks of poor water solubility, short emission wavelength, poor stability, and inability to distinguish cancer cells from normal cells limit the application of most type I PSs in clinical therapy. Thereby, developing novel type I PSs for overcoming these problems is an urgent but challenging task. Herein, by utilizing the distinctive structural characteristics of anion-π⁺ interactions, a highly water-soluble type I PS (DPBC-Br) with aggregation-induced emission (AIE) characteristic and near-infrared (NIR) emission is fabricated for the first time. DPBC-Br displays remarkable water solubility (7.3 mM) and outstanding photobleaching resistance, enabling efficient and precise differentiation between tumor cells and normal cells in a wash-free and long-term tracking manner via NIR-I imaging. Additionally, the superior type I reactive oxygen species (ROS) produced by DPBC-Br provide both specific killing of cancer cells in vitro and inhibition of tumor growth in vivo, with negligible systemic toxicity. This study rationally constructs a highly water-soluble type I PS, which has higher reliability and controllability compared with conventional nanoparticle formulating procedures, offering great potential for clinical cancer treatment.     

双齿甜菜碱衍生物大环及双环镉(Ⅱ)配位化合物的合成与晶体结构

利用甜菜碱衍生物1,5-二(4-羧基吡啶基)-N-甲基二乙胺(L)合成了两种镉(Ⅱ)的配位化合物[Cd2Cl4(H2O)2L2].2H2O和[Cd2(SCN)4(μ-H2O)L2]。用X-射线单晶衍射仪测定了配合物的单晶结构,并对它们进行了元素分析、红外光谱、1H NMR、热重等表征。结构分析表明,前者具有三十六元大环框架,而后者为双环结构。由于缺乏分子之间的强烈相互作用,弱相互作用决定了这两种化合物在晶格中的堆积模式:前者由相邻分子间的π-π和C-H…π相互作用而堆积形成二维砖墙的结构;后者由配位的SCN-阴离子通过S…S弱相互作用联接成一维链状结构。