Nitrogen-Site Engineering in Covalent Organic Frameworks for H2O2 Photogeneration via Dual Channels of Indirect Two-Electron O2 Reduction.

Photocatalytic H2O2 production is a green and sustainable route, but far from meeting the increasing demands of industrialization due to the rapid recombination of the photogenerated charge carriers and the sluggish reaction kinetics. Effective strategies for precisely regulating the photogenerated carrier behavior and catalytic activity to construct high-performance photocatalysts are urgently needed. Herein, a nitrogen-site engineering strategy, implying elaborately tuning the species and densities of nitrogen atoms, is applied for H2O2 photogeneration performance regulation. Different nitrogen heterocycles, such as pyridine, pyrimidine, and triazine units, are polymerized with trithiophene units, and five covalent organic frameworks (COFs) with distinct nitrogen species and densities on the skeletons are obtained. Fascinatingly, they photocatalyzed H2O2 production via dominated two-electron O2 reduction processes, including O2-O2 •‒-H2O2 and O2-O2 •‒-O2 1-H2O2 dual pathways. Just in the air and pure water, the multicomponent TTA-TF-COF with the maximum nitrogen densities triazine nitrogen densities exhibited the highest H2O2 production rate of 3343 µmol g-1 h-1, higher than most of other reported COFs. The theoretical calculation revealed the higher activity is due to the easy formation of O2 •‒ and O2 1 in different catalytic process. This study gives a new insight into designing photocatalysis at atomic level.

Regulating the Topology of Covalent Organic Frameworks for Boosting Overall H2O2 Photogeneration.

Photocatalytic oxygen reduction reactions and water oxidation reactions are extremely promising green approaches for massive H2O2 production. Nonetheless, constructing effective photocatalysts for H2O2 generation is critical and still challenging. Since the network topology has significant impacts on the electronic properties of two dimensional (2D) polymers, herein, for the first time, we regulated the H2O2 photosynthetic activity of 2D covalent organic frameworks (COFs) by topology. Through designing the linking sites of the monomers, we synthesized a pair of novel COFs with similar chemical components on the backbones but distinct topologies. Without sacrificial agents, TBD-COF with cpt topology exhibited superior H2O2 photoproduction performance (6085 and 5448 µmol g-1 h-1 in O2 and air) than TBC-COF with hcb topology through the O2-O2⋅--H2O2, O2-O2⋅--O2 1-H2O2, and H2O-H2O2 three paths. Further experimental and theoretical investigations confirmed that during the H2O2 photosynthetic process, the charge carrier separation efficiency, O2⋅- generation and conversion, and the energy barrier of the rate determination steps in the three channels, related to the formation of *OOH, *O2 1, and *OH, can be well tuned by the topology of COFs. The current study enlightens the fabrication of high-performance photocatalysts for H2O2 production by topological structure modulation.

Mixed-Linkage Donor-Acceptor Covalent Organic Framework as a Turn-On Fluorescent Sensor for Aliphatic Amines.

Amine determination is crucial to our daily life, including the prevention of pollution, the treatment of certain disorders, and the evaluation of food quality. Herein, a mixed-linkage donor-acceptor covalent organic framework (named DSE-COF) was first constructed by the polymerization between 2,4-dihydroxybenzene-1,3,5-tricarbaldehyde (DTA) and 4,4'-(benzo[c][1,2,5]selenadiazole-4,7-diyl)dianiline (SEZ). DSE-COF displayed superior turn-on fluorescent responses to primary, secondary, and tertiary aliphatic amines, such as cadaverine, isopropylamine, sec-butylamine, cyclohexylamine, hexamethylenediamine, di-n-butylamine, and triethylamine in absolute acetonitrile than other organic species. Further experiments and theoretical calculations demonstrated that the combination of intramolecular charge transfer (ICT) and photoinduced electron transfer (PET) effects between the DSE-COF and aliphatic amines resulted in enhanced fluorescence. Credibly, DSE-COF can quantitatively detect cadaverine content in actual pork samples with satisfactory results. In addition, DSE-COF-based test papers could rapidly monitor cadaverine from real pork samples, manifesting the potential application of COFs in food quality inspection.

Thiophene-Containing Covalent Organic Frameworks for Overall Photocatalytic H2 O2 Synthesis in Water and Seawater.

H2 O2 is a significant chemical widely utilized in the environmental and industrial fields, with growing global demand. Without sacrificial agents, simultaneous photocatalyzed H2 O2 synthesis through the oxygen reduction reaction (ORR) and water oxidation reaction (WOR) dual channels from seawater is green and sustainable but still challenging. Herein, two novel thiophene-containing covalent organic frameworks (TD-COF and TT-COF) were first constructed and served as catalysts for H2 O2 synthesis via indirect 2e- ORR and direct 2e- WOR channels. The photocatalytic H2 O2 production performance can be regulated by adjusting the N-heterocycle modules (pyridine and triazine) in COFs. Notably, with no sacrificial agents, just using air and water as raw materials, TD-COF exhibited high H2 O2 production yields of 4060 µmol h-1 g-1 and 3364 µmol h-1 g-1 in deionized water and natural seawater, respectively. Further computational mechanism studies revealed that the thiophene was the primary photoreduction unit for ORR, while the benzene ring (linked to the thiophene by the imine bond) was the central photooxidation unit for WOR. The current work exploits thiophene-containing COFs for overall photocatalytic H2 O2 synthesis via ORR and WOR dual channels and provides fresh insight into creating innovative catalysts for photocatalyzing H2 O2 synthesis.

Chiral Ionic Covalent Organic Framework as an Enantioselective Fluorescent Sensor for Phenylalaninol Determination.

Phenylalaninol (PAL) is a significant chemical intermediate widely utilized in drug development and chiral synthesis, for instance, as a reactant for bicyclic lactams and oxazoloisoindolinones. Since the absolute stereochemical configuration significantly impacts biological action, it is crucial to evaluate the concentration and enantiomeric content of PAL in a quick and convenient manner. Herein, an effective PAL enantiomer recognition method was reported based on a chiral ionic covalent organic framework (COF) fluorescent sensor, which was fabricated via one-step postquaternization modification of an achiral COF by (1R, 2S, 5R)-2-isopropyl-5-methylcyclohexyl-carbonochloridate (L-MTE). The formed chiral L-TB-COF can be applied as a chiral fluorescent sensor to recognize the stereochemical configuration of PAL, which displayed a turn-on fluorescent response for R-PAL over that of S-PAL with an enantioselectivity factor of 16.96. Nonetheless, the single L-MTE molecule had no chiral recognition ability for PAL. Moreover, the ee value of PAL can be identified by L-TB-COF. Furthermore, density functional theory (DFT) calculations demonstrated that the chiral selectivity came from the stronger binding affinity between L-TB-COF and R-PAL in comparison to that with S-PAL. L-TB-COF is the first chiral ionic COF employed to identify chiral isomers by fluorescence. The current work expands the range of applications for ionic COFs and offers fresh suggestions for creating novel chiral fluorescent sensors.

Hypertension in China: burdens, guidelines and policy responses: a state-of-the-art review.

Hypertension is a leading risk factor of cardiovascular disease and it is becoming increasingly prevalent globally. Correspondingly, the Chinese government and public health institutions have issued a series of policy documents and guidelines for hypertension. However, no comprehensive review of such documents has been conducted. Hence, this review aims to provide an up-to-date and comprehensive assessment of not only the disease burden, but also hypertension management policies and guidelines in China. A total of 15 epidemiological studies based on national population surveys, 15 Chinese Hypertension Guidelines, and seven policy documents were identified. We found a larger burden of hypertension in men, while the awareness, treatment, and control rates have remained low in both sexes. The ranges of hypertension prevalence, awareness, treatment, and control rate among hypertensive patients were 18.0-44.7%, 23.6-56.2%, 14.2-48.5%, and 4.2-30.1% respectively. Chinese hypertension guidelines provide evidence-based instructions to healthcare practitioners over hypertension management in which primary healthcare is increasingly emphasized. Finally, the policy documents set national goals for hypertension management and standardized the services provided in primary healthcare. The findings highlight the importance of integrating new guidelines into hypertension management provided by primary healthcare practitioners and the need to evaluate the implementation of guidelines and policies.

Perceptions of e-cigarettes among smokers and non-smokers in households with children in rural China: A cross-sectional study.

INTRODUCTION: The perceived health benefits and effectiveness of electronic cigarettes (e-cigarettes) in quitting smoking may affect e-cigarette usage, however, research on the use of e-cigarettes among the Chinese, especially among the rural Chinse, is scarce. This study examined factors associated with perceptions of e-cigarette related harms, benefits, and addictiveness, among smoker and non-smoker households with children in rural China, to support the design of population-based interventions targeting rural Chinese households. METHODS: In a cross-sectional study design, using a structured questionnaire, we collected data from the household members of children in two selected rural communities in China. Descriptive analyses were used to characterize respondents; χ2 test and Fisher's exact probability test were used to compare the perceptions of e-cigarettes between different sociodemographic groups. Logistic regression was used to determine predictors for e-cigarette harms, benefits, and addictiveness, adjusting for demographic and other characteristics. RESULTS: The overall participation rate was 81% (1211/1498). Of the participants, 668 (55%) were smokers and 543 (45%) were non-smokers; 53% knew about e-cigarettes. Participants from rural Dali (77% vs 59%), those who were ethnic minority (76% vs 59%), those who perceived increased COPD risks from smoking (mean score 4.37 vs 4.18) and concerned about harmful effects of secondhand smoke (SHS) exposure to children (mean score 4.48 vs 4.30) and adults (mean score 4.06 vs 3.87) were more likely to believe that e-cigarettes were less harmful (p<0.05). Participants with more knowledge about the harm of smoking were more likely to believe that e-cigarettes were helpful in quitting smoking (p<0.05). Of those participants who knew about e-cigarettes, females (19%) were significantly more likely to believe that e-cigarettes are addictive than males (10%). In the logistic regression analyses, believing e-cigarettes are helpful to quit smoking was the only variable associated with holding a higher knowledge about smoking and SHS exposure (OR=0.608; 95% CI: 0.450-0.820). CONCLUSIONS: Our results showed that more than half of the rural household members who have a child at home were aware of e-cigarettes. Knowledge about health impacts of SHS exposure and perceptions about the benefits, harms and addictiveness of e-cigarette use varied among the participants, with a significant proportion of participants having wrong information. Public health campaigns to disseminate evidence-based information of e-cigarette benefits and harms are warranted. As knowledge about the harmfulness of smoking and SHS exposure was associated with perceived e-cigarette benefits, particular focus should be given to increasing knowledge about the health hazards related to smoking and SHS exposure.

To text or not to text? Acceptability of WeChat and text messaging intervention to promote tobacco control assistance among parents who smoke in rural China.

INTRODUCTION: Although the use of mobile health (mHealth) to promote tobacco control and smoking cessation interventions has been available in developed countries, their use in low- and middle-income countries (i.e. in China) is lacking. This study examined the acceptance of text messaging and/or WeChat based tobacco control intervention among parents who smoke, in rural China. METHODS: Using a structured questionnaire, we surveyed smoker households (n=668) of children aged ≤5 years in two rural regions of southern China. Descriptive analyses were used to characterize respondents; multivariate regression analysis was used to test the associations between participants' sociodemographic and other characteristics, and their acceptability of text messaging and/or WeChat intervention for tobacco control. RESULTS: After adjusting for other variables (i.e. region, ethnicity, age, education level, occupation, attitudes towards smoking, perception of cigarettes addictiveness, and quitting smoking), the overall knowledge about smoking and secondhand smoke (SHS) exposure significantly predicted a higher acceptance to text messaging/WeChat intervention (OR=0.567; 95% CI: 0.457-0.704). Participants who thought smoking made people feel relaxed were less likely to accept text messaging/WeChat intervention than those who did not think so (OR=1.403; 95% CI: 1.080-1.822). CONCLUSIONS: Our findings suggest that households in rural China that were more knowledgeable about the hazards of smoking and SHS exposure, and had negative feelings about the benefits of smoking, were more likely to accept text messaging/WeChat for tobacco control intervention. Understanding rural smokers' preferences to receive intervention and related characteristics can help with the design of targeted tobacco control intervention programs in rural China.