Spacer Conformation Induced Multiple Hydrogen Bonds in 2D Perovskite toward Highly Efficient Optoelectronic Devices

Two-dimensional (2D) Dion-Jacobson (DJ) perovskites typically outperform Ruddlesden-Popper (RP) analogs in terms of photodetection (PD). However, the mechanism behind this enhanced performance remains elusive. Theoretical calculations for elucidating interlayer spacer conformation-induced multiple hydrogen bonds in 2D perovskite are presented, along with the synthesis of DPAPbBr4 (DPB) single crystals (SCs) and their PD properties under X-ray/ultraviolet (UV) excitation. The high-quality DPB SC enhances PD with exceptional photoresponse attributes, including a high on/off ratio (4.89 × 104), high responsivity (2.44 A W⁻1), along with large dynamic linear range (154 dB) and low detection limit (7.1 nW cm⁻2), which are currently the best results among 2D perovskite SC detectors, respectively. Importantly, high-resolution images are obtained under UV illumination with weak light levels. The SC X-ray detector exhibits a high sensitivity of 663 µC Gyair⁻1 cm-2 at 10 V and a detection limit of 1.44 µGyair s⁻1. This study explores 2D DJ perovskites for efficient and innovative optoelectronic applications.

Enantioconvergent synthesis of chiral fluorenols from racemic secondary alcohols via Pd(ii)/chiral norbornene cooperative catalysis

An efficient protocol for the asymmetric synthesis of fluorenols has been developed through an enantioconvergent process enabled by Pd(ii)/chiral norbornene cooperative catalysis. This approach allows facile access to diverse functionalized chiral fluorenols with constantly excellent enantioselectivities, applying readily available racemic secondary ortho-bromobenzyl alcohols and aryl iodides as the starting materials.

[Study on the correlation between thyroid nodule and metabolic index in physical examination population]

Objective: By analyzing the prevalence and influencing factors of thyroid nodules (TN) among a population undergoing physical examinations in Nantong region, this study aims to provide theoretical basis for early prevention and intervention of TN. Methods: A cross-sectional study was conducted, including 6 950 participants who underwent physical examinations at the Affiliated Hospital of Nantong University from January 2017 to April 2020. All participants underwent high-resolution ultrasound examination of the thyroid, and measurements of height, body mass index (BMI), blood pressure. Fasting blood glucose (FBG), total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), uric acid (UA), homocysteine (HCY) and other metabolic indicators were detected. Data analysis was performed using SPSS 26.0 statistical software. The numerical variables with normal distribution were expressed as mean±standard deviation (x¯±s), and the t-test was used for comparison between the two groups. Numerical variables with non-normal distribution were expressed as median (interquartile range), namely M (Q1, Q3). The Mann-Whitney U test was used for comparison between two groups, and the Kruskal-Wallis test was used for comparison between multiple groups. Results: The prevalence of thyroid nodules among the 6 950 participants was 53.97% (3 751/6 950), with a rate of 47.08% (2 218/4 711) in males and 68.47% (1 533/2 239) in females, which was significantly higher in females than in males (χ2=278.575, P<0.001). The prevalence of TN increased with age both overall (χ2=552.145, P<0.001), in males (χ2=304.086, P<0.001), and in females (χ2=202.178, P<0.001). The prevalence of TN was higher in females than in males across different age groups (P<0.05). In the comparison between males in the TN and non-TN groups, significant differences were found in terms of alcohol consumption history, BMI, blood pressure, HCY, and FBG (all P<0.05). In the comparison between females in the TN and non-TN groups, significant differences were found in terms of BMI, blood pressure, HCY, FBG, TC, TG, LDL-C, and UA (all P<0.05). Univariate logistic regression model showed that FBG<6.1 mmol/L (P<0.001) and TC<5.2 mmol/L (P=0.013) were protective factors for TN. Normal UA (P=0.013) was a risk factor for TN. After adjusting for gender, smoking, alcohol consumption, BMI, and blood pressure, multivariate logistic regression analysis revealed that FBG<6.1 mmol/L (OR: 0.713, 95%CI: 0.621-0.817, P<0.001) was a protective factor against TN. Conclusion: The prevalence of TN is relatively high in the Nantong region. Gender, age, blood pressure, BMI, and FBG are important influencing factors for TN. Health screening and management should be strengthened for the physical examination population with abnormal indicators.

Unveiling the Electrolyte Cations Dependent Kinetics on CoOOH-Catalyzed Oxygen Evolution Reaction

The electrolyte cations-dependent kinetics have been widely observed in many fields of electrocatalysis, however, the exact mechanism of the influence on catalytic performance is still a controversial topic of considerable discussion. Herein, combined with operando X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), we verify that the electrolyte cations could intercalate into the layer of pristine CoOOH catalyst during the oxygen evolution reaction (OER) process, while the bigger cations lead to enlarged interlayer spacing and increased OER activity, following the order Cs+ >K+ >Na+ >Li+ . X-ray absorption spectroscopy (XAS), in situ Raman, in situ Ultraviolet-visible (UV/Vis) spectroscopy, in situ XAS spectroscopy, cyclic voltammetry (CV), and theoretical calculations reveal that the intercalation of electrolyte cations efficiently modify the oxidation states of Co by enlarging the Co-O bonds, which in turn enhance the d-band center of Co, optimize the adsorption strength of oxygen intermediates, facilitate the formation of OER active Co(IV) species, and reduce the energy barrier of the rate-determing step (RDS), thereby enhancing the OER activity. This work not only provides an informative picture to understand the complicated dependence of OER kinetics on electrolyte cations, but also sheds light on understanding the mechanism of other electrolyte cation-targeted electrocatalysis.

[Application of preoperative serum CYFRA 21-1 level in the prognosis of colorectal cancer]

To explore the predictive value of preoperative serum CYFRA 21-1 in colorectal cancer (CRC) resection patients. In this retrospective study, 456 patients with CRC who received surgical treatment in the Department of General Surgery, Affiliated Hospital of Nantong University from January 2016 to February 2018 were analyzed. Preoperative CYFRA 21-1, CEA, CA19-9 and pathological data of the study subjects were collected. Determine the cut-off value of CYFRA 21-1 based on the X-tile. Chi-square test or Fisher exact probability test were used to compare clinicopathological features in different CYFRA 21-1 level groups. Univariate and multivariate regression analysis of factors affecting 5-year overall survival (OS) and disease-free survival (DFS). Kaplan-Meier survival curves were used to analyze 5-year differences in OS and DFS in CRC patients with different levels of CYFRA 21-1, CEA and CA19-9. Receiver operating characteristic(ROC) was adopted. ROC curves were used to analyze the prognostic efficacy of CYFRA21-1 for CRC, and nomogram maps were used to predict 1, 3, and 5-year survival rates. The results showed that the optimal cut-off values of serum CYFRA 21-1, CEA and CA19-9 were 4.9 ng/ml, 29.2 ng/ml and 72.8 U/ml, respectively. Different gender, tumor size, location, degree of differentiation, depth of invasion, lymph node metastasis and tumor node metastasis (TNM) classification stage were significantly different between the two groups with high and low CYFRA 21-1, the P-values were 0.018,<0.001,<0.001,<0.001, 0.002, 0.001, 0.003, respectively. CYFRA 21-1 (≥4.9 ng/ml) was an independent risk factor for 5-year OS (HR: 4.008, 95%CI: 2.309-6.958, P<0.001) and DFS (HR: 3.75, 95%CI: 2.227-6.314, P<0.001) in CRC patients. CYFRA 21-1 predicts a 5-year AUC of 0.725 and 0.720 for OS and DFS, respectively, and 0.804 and 0.827 for the combination of CEA and CA19-9. Based on the results of multivariate Cox regression analysis, nomogram graphs of OS and DFS were established, the C-indexes were 0.799 and 0.803, respectively. In conclusion, preoperative serum CYFRA 21-1 level may be an independent risk factor affecting the prognosis of patients with colorectal cancer. The prognostic model established by CYFRA 21-1 combined with CEA, CA19-9 and TNM stages may provide references for the prevention of CRC recurrence and clinical decision-making.

Valve turning towards on-cycle in cobalt-catalyzed Negishi-type cross-coupling

Ligands and additives are often utilized to stabilize low-valent catalytic metal species experimentally, while their role in suppressing metal deposition has been less studied. Herein, an on-cycle mechanism is reported for CoCl2bpy2 catalyzed Negishi-type cross-coupling. A full catalytic cycle of this kind of reaction was elucidated by multiple spectroscopic studies. The solvent and ligand were found to be essential for the generation of catalytic active Co(I) species, among which acetonitrile and bipyridine ligand are resistant to the disproportionation events of Co(I). Investigations, based on Quick-X-Ray Absorption Fine Structure (Q-XAFS) spectroscopy, Electron Paramagnetic Resonance (EPR), IR allied with DFT calculations, allow comprehensive mechanistic insights that establish the structural information of the catalytic active cobalt species along with the whole catalytic Co(I)/Co(III) cycle. Moreover, the acetonitrile and bipyridine system can be further extended to the acylation, allylation, and benzylation of aryl zinc reagents, which present a broad substrate scope with a catalytic amount of Co salt. Overall, this work provides a basic mechanistic perspective for designing cobalt-catalyzed cross-coupling reactions.

Promoting water formation in sulphate-functionalized Ru for efficient hydrogen oxidation reaction under alkaline electrolytes

Improving the sluggish kinetics of the hydrogen oxidation reaction (HOR) under alkaline electrolytes plays a significant role in the practical application of alkaline polymer electrolyte fuel cells (APEFCs). Here we report a sulphate functionalized Ru catalyst (Ru-SO₄) that exhibits remarkable electrocatalytic performance and stability toward alkaline HOR, with a mass activity of 1182.2 mA mg_PGM^-1, which is four-times higher than that of the pristine Ru catalyst. Theoretical calculations and experimental studies including in situ electrochemical impedance spectroscopy and in situ Raman spectroscopy demonstrate that the charge redistribution on the interface of Ru through sulphate functionalization could lead to optimized adsorption energies of hydrogen and hydroxide, together with facilitated H₂ transfer through the inter Helmholtz plane and precisely tailored interfacial water molecules, contributing to a decreased energy barrier of the water formation step and enhanced HOR performance under alkaline electrolytes.

Hydroxyl-Binding Energy-Induced Kinetic Gap Narrowing between Acidic and Alkaline Hydrogen Oxidation Reaction on Intermetallic Ru3 Sn7 Catalyst

Developing highly efficient catalysts toward alkaline hydrogen oxidation reaction (HOR) and narrowing the kinetic gap between acidic and alkaline electrolytes are of great importance for the practical application of alkaline exchange membrane fuel cell . Herein, ordered Ru₃ Sn₇ /C intermetallic compound has been developed for the HOR under alkaline and acidic conditions. The authors demonstrate that the ordered intermetallic Ru₃ Sn₇ /C shows much enhanced HOR activity, stability, and CO-tolerance compared with its disordered RuSn solid solution alloy counterpart. More importantly, the authors find that the kinetic gap of HOR between acidic and alkaline media is significantly narrowed in the as-synthesized intermetallic Ru₃ Sn₇ /C catalysts. Combined experiment results and theoretical calculations, the authors understand that promoted hydroxyl-binding energy on Ru₃ Sn₇ /C derived from the intermetallic-induced strong electron interaction is responsible for the accelerated alkaline HOR performance and narrowed kinetic gap.

Enantioselective Assembly of Ferrocenes with Axial and Planar Chiralities via Palladium/Chiral Norbornene Cooperative Catalysis

The preparation of ferrocenes with both axial and planar chiralities poses a considerable challenge. Herein, we report a strategy for the construction of both axial and planar chiralities in a ferrocene system via palladium/chiral norbornene (Pd/NBE*) cooperative catalysis. In this domino reaction, the first established axial chirality is dictated by Pd/NBE* cooperative catalysis, while the latter planar chirality is controlled by the preinstalled axial chirality through a unique axial-to-planar diastereoinduction process. This method exploits readily available ortho-ferrocene-tethered aryl iodides (16 examples) and the bulky 2,6-disubstituted aryl bromides (14 examples) as the starting materials. Five- to seven-membered benzo-fused ferrocenes with both axial and planar chiralities (32 examples) are obtained in one step with constantly high enantioselectivities (>99% e.e.) and diastereoselectivities (>19:1 d.r.).

Unraveling the Structure and Reactivity Patterns of the Indole Radical Cation in Regioselective Electrochemical Oxidative Annulations

Oxidation-induced strategy for inert chemical bond activation through highly active radical cation intermediate has exhibited unique reactivity. Understanding the structure and reactivity patterns of radical cation intermediates is crucial in the mechanistic study and will be beneficial for developing new reactions. In this work, the structure and properties of indole radical cations have been revealed using time-resolved transient absorption spectroscopy, in situ electrochemical UV-vis, and in situ electrochemical electron paramagnetic resonance (EPR) technique. Density functional theory (DFT) calculations were used to explain and predict the regioselectivity of several electrochemical oxidative indole annulations. Based on the understanding of the inherent properties of several indole radical cations, two different regioselective annulations of indoles have been successfully developed under electrochemical oxidation conditions. Varieties of furo[2,3-b]indolines and furo[3,2-b]indolines were synthesized in good yields with high regioselectivities. Our mechanistic insights into indole radical cations will promote the further development of oxidation-induced indole functionalizations.

Synergistic passivation and stepped-dimensional perovskite analogs enable high-efficiency near-infrared light-emitting diodes

Formamidinium lead iodide (FAPbI₃) perovskites are promising emitters for near-infrared light-emitting diodes. However, their performance is still limited by defect-assisted nonradiative recombination and band offset-induced carrier aggregation at the interface. Herein, we introduce a couple of cadmium salts with acetate or halide anion into the FAPbI₃ perovskite precursors to synergistically passivate the material defects and optimize the device band structure. Particularly, the perovskite analogs, containing zero-dimensional formamidinium cadmium iodide, one-dimensional δ-FAPbI₃, two-dimensional FA₂FA_n-1Pb_nI_3n+1, and three-dimensional α-FAPbI₃, can be obtained in one pot and play a pivotal and positive role in energy transfer in the formamidinium iodide-rich lead-based perovskite films. As a result, the near-infrared FAPbI₃-based devices deliver a maximum external quantum efficiency of 24.1% together with substantially improved operational stability. Combining our findings on defect passivation and energy transfer, we also achieve near-infrared light communication with device twins of light emitting and unprecedented self-driven detection.

[Correlation between serum uric acid and creatinine ratio and metabolic syndrome based on physical examination population in Nantong area]

To investigate the relationship between serum uric acid to creatinine ratio (SUA/Cr) and metabolic syndrome (MS) and other indexes on physical examination population in Nantong area. Using the method of cross-sectional study, 8 148 physical examiners in the physical examination center of the Affiliated Hospital of Nantong University from January 2017 to April 2020 were used as the research objects, and the clinical data and serum biochemical indicators such as smoking and alcohol addiction, physical examination and so on were collected. According to the standard diagnosis of MS of Diabetes Society of Chinese Medical Association, the patients were grouped according to the quartile of SUA/Cr and the clinical data of each group were compared. Pearson correlation analysis and logistic regression analysis were used to explore the correlation between SUA/Cr and clinical indicators and the relationship between SUA/Cr and the risk of MS. The results showed that UA and SUA/Cr were the lowest in normal metabolism group, followed by abnormal metabolism group and the highest in MS group, The difference between the two groups was statistically significant (H=919.21 and 629.34, P<0.001). According to the SUA/Cr quartile, the population was divided into four groups. After adjusting for gender, age, smoking history and drinking history, SUA/Cr in group Q₁ was positively correlated with BMI and TG (r=0.061 and 0.080, P<0.05), but negatively correlated with HDL-C (r=-0.057, P<0.05). Multivariate logistic regression results showed that after adjusting for age, sex, smoking history and drinking history, the risk of MS for BMI, SBP, DBP, FBG, TG, HDL-C and SUA/Cr [OR (95%CI)] were: 1.44 (1.41-1.47), 1.07 (1.06-1.07), 1.10 (1.10-1.11), 1.83 (1.73-1.92), 1.89 (1.79-1.99), 0.08 (0.06-0.10) and 1.54 (1.47-1.62). Compared with SUA/Cr group Q₁, the risk of MS in group Q₂, Q₃ and Q₄ increased by 75%, 162% and 346%, respectively. In conclusion, there was an independent positive correlation between SUA/Cr and MS risk in Nantong area.

From N-H Nitration to Controllable Aromatic Mononitration and Dinitration-The Discovery of a Versatile and Powerful N-Nitropyrazole Nitrating Reagent

Nitroaromatics are tremendously valuable organic compounds with a long history of being used as pharmaceuticals, agrochemicals, and explosives as well as vital intermediates to a wide variety of chemicals. Consequently, the exploration of aromatic nitration has become an important endeavor in both academia and industry. Herein, we report the identification of a powerful nitrating reagent, 5-methyl-1,3-dinitro-1H-pyrazole, from the N-nitro-type reagent library constructed using a practical N-H nitration method. This nitrating reagent behaves as a controllable source of the nitronium ion, enabling mild and scalable nitration of a broad range of (hetero)arenes with good functional group tolerance. Of note, our nitration method could be controlled by manipulating the reaction conditions to furnish mononitrated or dinitrated product selectively. The value of this method in medicinal chemistry has been well established by its efficient late-stage C-H nitration of complex biorelevant molecules. Density functional theory (DFT) calculations and preliminary mechanistic studies reveal that the powerfulness and versatility of this nitrating reagent are due to the synergistic "nitro effect" and "methyl effect".

Intermolecular Energy Gap-Induced Formation of High-Valent Cobalt Species in CoOOH Surface Layer on Cobalt Sulfides for Efficient Water Oxidation

Transition metal-based electrocatalysts will undergo surface reconstruction to form active oxyhydroxide-based hybrids, which are regarded as the "true-catalysts" for the oxygen evolution reaction (OER). Much effort has been devoted to understanding the surface reconstruction, but little on identifying the origin of the enhanced performance derived from the substrate effect. Herein, we report the electrochemical synthesis of amorphous CoOOH layers on the surface of various cobalt sulfides (CoS_α ), and identify that the reduced intermolecular energy gap (Δ_inter ) between the valence band maximum (VBM) of CoOOH and the conduction band minimum (CBM) of CoS_α can accelerate the formation of OER-active high-valent Co⁴⁺ species. The combination of electrochemical and in situ spectroscopic approaches, including cyclic voltammetry (CV), operando electron paramagnetic resonance (EPR) and Raman, reveals that Co species in the CoOOH/Co₉ S₈ are more readily oxidized to CoO₂ /Co₉ S₈ than in CoOOH and other CoOOH/CoS_α . This work provides a new design principle for transition metal-based OER electrocatalysts.

Electronic Modulation of Ru Nanosheet by d-d Orbital Coupling for Enhanced Hydrogen Oxidation Reaction in Alkaline Electrolytes

The alkaline polymer electrolyte fuel cells (APEFCs) hold great promise for using nonnoble metal-based electrocatalysts toward the cathodic oxygen reduction reaction (ORR), but are hindered by the sluggish anodic hydrogen oxidation reaction (HOR) in alkaline electrolytes. Here, a strategy is reported to promote the alkaline HOR performance of Ru by incorporating 3d-transition metals (V, Fe, Co, and Ni), where the conduction band minimum (CBM) level of Ru can be rationally tailored through strong d-d orbital coupling. As expected, the obtained RuFe nanosheet exhibits outstanding HOR performance with the mass activity of 233.46 A g_PGM ^-1 and 23-fold higher than the Ru catalyst, even threefold higher than the commercial Pt/C. APEFC employing this RuFe as anodic catalyst gives a peak power density of 1.2 W cm^-2 , outperforming the documented Pt-free anodic catalyst-based APEFCs. Experimental results and density functional theory calculations suggest the enhanced OH-binding energy and reduced formation energy of water derived from the downshifted CBM level of Ru contribute to the enhanced HOR activity.

Selective radical cascade (4+2) annulation with olefins towards the synthesis of chroman derivatives via organo-photoredox catalysis

Due to the importance of chroman frameworks in medicinal chemistry, the development of novel synthetic methods for these structures is gaining increasing interest of chemists. Reported here is a new (4 + 2) radical annulation approach for the construction of these functional six-membered frameworks via photocatalysis. Featuring mild reaction conditions, the protocol allows readily available N-hydroxyphthalimide esters and electron-deficient olefins to be converted into a wide range of valuable chromans in a highly selective manner. Moreover, the present strategy can be used in the late-stage functionalization of natural product derivatives and biologically active compounds, which demonstrated the potential application. This method is complementary to the traditional Diels–Alder [4 + 2] cycloaddition reaction of ortho-quinone methides and electron-rich dienophiles, since electron-deficient dienophiles were smoothly transformed into the desired chromans.

We have developed a (4 + 2) radical annulation approach for the synthesis of diverse chromans. This method is complementary to the traditional Diels–Alder [4 + 2] annulation of ortho-quinone methides and electron-rich dienophiles.

Exfoliation of MoS2 Nanosheets Enabled by a Redox-Potential-Matched Chemical Lithiation Reaction

Ion intercalation assisted exfoliation is the oldest and most popular method for the scalable synthesis of molybdenum disulfide (MoS₂) nanosheets. The commonly used organolithium reagents for Li⁺ intercalation are n-butyllithium (n-BuLi) and naphthalenide lithium (Nap-Li); however, the highly pyrophoric nature of n-BuLi and the overly reducing power of Nap-Li hinder their extensive application. Here, a novel organolithium reagent, pyrene lithium (Py-Li), which has intrinsic safe properties and a well-matched redox potential, is reported for the intercalation and exfoliation of MoS₂. The redox potential of Py-Li (0.86 V vs Li⁺/Li) is located just between the intercalation (1.13 V) and decomposition (0.55 V) potentials of bulk MoS₂, thus allowing precise Li⁺ intercalation to form a lamellar LiMoS₂ compound without undesirable structural damage. The lithiation reaction can be accomplished within 1 h at room temperature and the exfoliated nanosheets are almost single layer. This method also offers the advantages of low cost, high repeatability, and ease in realizing large-scale production.

Enantioselective Nickel-Catalyzed Reductive Aryl/Alkenyl-Cyano Cyclization Coupling to All-Carbon Quaternary Stereocenters

An enantioselective nickel-catalyzed intramolecular reductive cross-coupling of C(sp²) electrophiles and cyano groups is reported. Enantioenriched CN-containing all-carbon quaternary stereocenters are assembled by desymmetrizing cyclization of aryl/alkenyl halide-tethered malononitriles. The use of an organic reductant, (EtO)₂MeSiH, is crucial to the enantioselectivity and reactivity. Applications of the method are demonstrated through the synthesis of bioactive molecules and their cyanated analogues and the total synthesis of the natural product diomuscinone. This study exhibits the potential of desymmetrizing reductive coupling strategies to access structurally rigid and synthetically versatile molecules from readily available starting materials.

Electrochemical dual-oxidation strategy enables access to α-chlorosulfoxides from sulfides

Electrochemistry contributes a strong tool for the manufacture of molecules, addressing intractable challenges in synthetic chemistry by enabling innovative reaction pathways. Herein, a bifunctional reagent, aqueous hydrochloric acid, is used to establish an electrochemical selective dual-oxidation approach that gives access to α-chlorosulfoxides from sulfides. This strategy presents broad substrate scope, high diastereoselectivity, and regioselectivity. The late-stage modification of amino acids and pharmaceutical derivatives further highlights the utility. Furthermore, detailed mechanistic studies reveal that the key success for this selective chemical transformation is the dual-oxidation process at the anode. This electrochemical dual-oxidation strategy may have wide universality; we anticipate diverse applications of this protocol across the many fields of chemistry.