3-Methylthio-5-hydroxy-1,2,4-triazine(1c)reacted with substituted benzenesulfonyl chloride to give 3-methylthio-5-oxy-1,2,4-triazin-6-yl pyridinium betaine(4)in anhydrous pyridine.But when NaOH/H_2O/CH_3COCH_3 or NaOH...3-Methylthio-5-hydroxy-1,2,4-triazine(1c)reacted with substituted benzenesulfonyl chloride to give 3-methylthio-5-oxy-1,2,4-triazin-6-yl pyridinium betaine(4)in anhydrous pyridine.But when NaOH/H_2O/CH_3COCH_3 or NaOH/CH_3OH were used as reactant and solvent,3-methylthio-4-substituted benzenesulfonyl-5-oxo-6-hydroxy-1,4,5,6-tetrahydro-1,2,4-triazine(6)or 1-tosyl-3-methylthio-5-oxo-6-methyloxy-1,4,5,6-tetrahydro-1,2,4-triazine(7)was obtained respectively.The above reactions show anomalous properties of nucleophilic attack on 6-carbon in 1,2,4-triazine ring.展开更多
Density functional theory B3LYP is employed to obtain the optimized geometries of the ground state and interaction energy for triazines and water complexes. The results show that the 1,2,3-triazine-water, 1,2,4-triazi...Density functional theory B3LYP is employed to obtain the optimized geometries of the ground state and interaction energy for triazines and water complexes. The results show that the 1,2,3-triazine-water, 1,2,4-triazine-water and 1,3,5-triazine-water complex on the ground state have Cs, Cs and C1 symmetry, and strong hydrogen bonding interaction with ?17.83, ?17.38 and ?13.55 kJ/mol after basis set superposition error and zero-point vibration energy correction, respectively, and large red-shift for the symmetric H─O stretching vibration frequencies forming N···H─O hydrogen bond in the triazines complex. The first singlet (n, π*) vertical excitation energy of the monomer and the hydrogen bonding complexes between triazines and water is investigated by time-dependent density functional theory.展开更多
The high conductivity of electrocatalyst can eliminate the Schottky energy barrier at the interface of heterogeneous phases during an electrocatalytic reaction and accelerate the rapid electron transfer to the catalyt...The high conductivity of electrocatalyst can eliminate the Schottky energy barrier at the interface of heterogeneous phases during an electrocatalytic reaction and accelerate the rapid electron transfer to the catalytic active center.Therefore,the electronic conductivity is a vital parameter for oxygen reduction reaction(ORR).Covalent triazine frameworks(CTFs)have shown great potential application as electrocatalysts in ORR with a merit of the diverse building blocks.However,the intrinsic low conductivity and high impedance of CTFs could be significant setbacks in electrocatalytic application.Herein,CTFs were constructed by introducing F and N co-modification for efficient 2e^(-)ORR.Compared with the pristine CTF,the co-presence of F,N could increase the conductivity obviously by 1000-fold.As a result,F-N-CTF exhibits enhanced catalytic performance of H_(2)O_(2)generation and selectivity towards reaction pathways.This work reveals the importance of conductivity optimization for CTFs and provides guidance for designing high conductivity non-metallic organic semiconductor catalysts for 2e^(-)ORR.展开更多
Photoinduced molecular oxygen activation is crucial for artificial photosynthesis.However,metal-free semiconductor photocatalysts with high activation efficiency are still lacking up to now.Herein,two isomorphic tris(...Photoinduced molecular oxygen activation is crucial for artificial photosynthesis.However,metal-free semiconductor photocatalysts with high activation efficiency are still lacking up to now.Herein,two isomorphic tris(triazolo)triazine-based covalent organic frameworks were successfully constructed under solvothermal conditions.And they possess high crystallinity,inherent porosity with large surface area and good stability.Strong electron donor-acceptor skeletons expand the visible light harvesting,also facilitate the charge separation and thus lead to their superior activity of photoinduced molecular oxygen activation including photosynthesis of tetrahydroquinolines and hydrogen peroxide.This work provides a way to improve the efficiency of molecular oxygen activation through the rational design of COFs,and also opens new avenues for the construction of highly active and metal-free photocatalysts toward sustainable solar-to-chemical energy conversion.展开更多
Converting CO_(2)and water into valuable chemicals like plant do is considered a promising approach to address both environmental and energy issues.Taking inspiration from the structures of natural leaves,we designed ...Converting CO_(2)and water into valuable chemicals like plant do is considered a promising approach to address both environmental and energy issues.Taking inspiration from the structures of natural leaves,we designed and synthesized a novel copper-coordinated covalent triazine framework(CuCTF)supported by silicon nanowire arrays on wafer chip.This marks the first-ever application of such a hybrid material in the photoelectrocatalytic reduction of CO_(2)under mild conditions.The Si@CuCTF6 heterojunction has exhibited exceptional selectivity of 95.6%towards multicarbon products(C_(2+))and apparent quantum efficiency(AQE)of 0.89%for carbon-based products.The active sites of the catalysts are derived from the nitrogen atoms of unique triazine ring structure in the ordered porous framework and the abundant Cu-N coordination sites with bipyridine units.Furthermore,through DFT calculations and operando FTIR spectra analysis,we proposed a comprehensive mechanism for the photoelectrocatalytic CO_(2)reduction,confirming the existence of key intermediate species such as*CO_(2)-,*=C=O,*CHO and*CO-CHO etc.This work not only provides a new way to mimic photosynthesis of plant leaves but also gives a new opportunity to enter this research field in the future.展开更多
FOR the purpose of finding novel antitumor and antivirus medicines and understanding themechanism of the metabolic process involved,several 6-azapurine derivatives were synthe-sized from 1,2,4-triazines.Mass spectrome...FOR the purpose of finding novel antitumor and antivirus medicines and understanding themechanism of the metabolic process involved,several 6-azapurine derivatives were synthe-sized from 1,2,4-triazines.Mass spectrometry plays a key role in the structure展开更多
As a continuation of the studies on the interference of metabolism of nucleic acids by 1,2,4-triazine derivatives, we have studied the preparation and chemical properties of a number of 1,2,4-triazines.
A number of azacalix[2]pyrimidine[2]triazines were synthesized in moderate to good yields from both a step-wise fragment coupling approach and a one-pot reaction strategy starting from 4,6-diaminopyrimidines and cyanu...A number of azacalix[2]pyrimidine[2]triazines were synthesized in moderate to good yields from both a step-wise fragment coupling approach and a one-pot reaction strategy starting from 4,6-diaminopyrimidines and cyanuric chloride.Nucleophilic aromatic substitution reaction of resulting dichloro-substituted azacalix[2]-pyrimidine[2]triazines with NH_(4)Cl led to the formation of NH_(2)-bearing azacalix[2]pyrimidine[2]triazine analogs.Azacalix[2]pyrimidine[2]triazines adopted symmetric 1,3-alternate conformations in solution while twisted 1,3-alternate conformations were observed in the solid state.In the presence of different additives during the growth of single crystals,azacalix[2]pyrimidine[2]triazines containing amino(-NH_(2))groups gave varied self-assembled structures due to the formation of different intermolecular hydrogen bond motifs.展开更多
The 1,3-dipolar cycloaddition of an azomethine ylide generated by a decarboxylative route from sarcosine and acenaphthenequinone to 7-arylmethylidene-3-aryl-3,4-dihydro-2H-thiazolo[3,2-aJ[1,3,5]triazin-6（7H）-ones af...The 1,3-dipolar cycloaddition of an azomethine ylide generated by a decarboxylative route from sarcosine and acenaphthenequinone to 7-arylmethylidene-3-aryl-3,4-dihydro-2H-thiazolo[3,2-aJ[1,3,5]triazin-6（7H）-ones afforded novel dispiro[acenaphthylene-1,2’-pyrrolidine]-3＇,7″-[1,3]thiazolo[3,2-a][1,3,5]triazines in moderate yields. The structures of the products were determined and characterized thoroughly by NMR, MS, IR, elemental analysis and X-ray crystallographic analysis. The results of experiment indicated that this 1,3-dipolar cycloaddition proceeded with high stereoselectivity and regioselectivity.展开更多
Polymeric carbon nitride(PCN)has garnered increasing attention as a metal-free photocatalyst with a suitable band gap.In efforts to enhance its photocatalytic performance,researchers have examined various PCN material...Polymeric carbon nitride(PCN)has garnered increasing attention as a metal-free photocatalyst with a suitable band gap.In efforts to enhance its photocatalytic performance,researchers have examined various PCN materials,including poly(heptazine imide)(PHI)and poly(triazine imide)(PTI),two isomers within the PCN family that exhibit distinct and superior photocatalytic activity compared to other forms.The challenge,however,lies in the common practice among researchers to categorize PHI and PTI along with other PCN types under the overarching term“g-C_(3)N_(4),”which significantly impedes optimization efforts.The objective of this review is to provide comprehensive insights into the structural features,photoelectrochemical properties,and effective characterization methods employed for distinguishing between PHI and PTI materials.The review also summarizes various optimization strategies,such as crystallinity adjustments,defect engineering,morphology control,constructing heterojunction,and atomic-level metal loading dispersion,to elevate the photocatalytic activity of PHI and PTI,in addition to summarizing the history of carbon nitride development.Furthermore,this review highlights the primary applications of PHI and PTI,encompassing nitrogen fixation,biomass conversion,organic synthesis,CO_(2)reduction,pollutant degradation,H_(2)O_(2)production,and photocatalytic water splitting.Lastly,the prospects and challenges associated with further advancing PHI and PTI are thoroughly examined.展开更多
Poly(triazine imide),as a kind of highly crystalline g-C_(3)N_(4),exhibits a promising potential for photo-catalytic hydrogen production,however,some drawbacks still limit its photocatalytic performance.The strategy o...Poly(triazine imide),as a kind of highly crystalline g-C_(3)N_(4),exhibits a promising potential for photo-catalytic hydrogen production,however,some drawbacks still limit its photocatalytic performance.The strategy of constructing S-scheme heterojunction with different semiconductor photocatalysts enables the effective separation of photogenerated electrons and holes,and the strong oxidative and reductive properties of the original photocatalysts could be retained,which will significantly improve the photo-catalytic activity.In this work,we synthesized the organic-organic S-scheme heterojunction between PTI and organic small molecule poly(barbituric acid)(PBA)by hydrogen bond self-assembly method,which results in a significant enhancement of photocatalytic H_(2)production activity.The H_(2)production rate of the optimum PBA/PTI-2 sample under visible light irradiation is about 0.92 mmol g^(-1),which is 5.5 times higher than that of PTI and 14.4 times higher than that of PBA.This excellent photocatalytic performance is attributed to the successful construction of S-scheme heterojunction between PTI and PBA,which ef-fectively accelerates carrier transport and spatial segregation by the formation of a built-in electric field and band bending at the interface.In addition,the S-scheme heterojunction could also reserve the maxi-mum redox capability and enhance the light absorption of the prepared photocatalytic system.This work provides a new strategy and understanding for the design and development of organic-organic S-scheme heterojunction photocatalysts.展开更多
In recent years,photocatalysis with efficient,low-cost and stable metal-free catalysts is one of the most promising technologies for non-polluting energy production and resource-economic environment purifying.Benefiti...In recent years,photocatalysis with efficient,low-cost and stable metal-free catalysts is one of the most promising technologies for non-polluting energy production and resource-economic environment purifying.Benefiting from the molecularly precise backbones,regular and homogeneous porosity,lightelement composition,nitrogen-rich system with unique electronic band structure of two-dimensional(2D)covalent triazine framework(CTF),as well as the huge specific surface area,superior thermal conductivity,excellent carrier mobility and mechanical properties of 2D graphene,CTF/graphene hybrid-based photocatalysts show great application potential in the field of photocatalysis.In this review,the recent development in synthesis of CTF/graphene hybrid-based photocatalysts,and their applications in photocatalytic water splitting for hydrogen production and photocatalytic degradation of pollutants are summarized.Firstly,we briefly describe the molecular structures,physicochemical properties,and synthetic strategies for CTF/graphene hybrid-based photocatalysts including solution mixing method,in-situ polymerization method and sol-gel method.We further assess the impact of different preparation methods on the structure,morphology,and interacting model between CTF and graphene in CTF/graphene hybrids.Following the various preparation process for CTF/graphene hybrid-based photocatalysts,these methods are analyzed and compared regarding their merits and demerits.Secondly,the functions of CTF/graphene hybrid-based photocatalysts obtained from different synthesis approaches that enhance the catalytic activity for photocataLytic hydrogen evolution and photocatalytic degradation of pollutants are discussed from the three aspects of light harvesting,charge separation and transfer,and surface catalysis.Particular focus has been placed on the catalytic mechanisms of CTF/graphene hybridbased photocatalysts for enhanced photocatalytic hydrogen evolution and improved photocatalytic degradation of pollutants.Then the rational manipulation of selection and building units of CTF,connecting bonds between CTF and graphene,dimensions and pore structures of CTF/graphene hybrids in design of CTF/graphene hybrid-based photocatalysts is discussed,aiming to inspire critical thinking about the effective strategies for modification of photocatalysts rather than the development of novel materials.In the end,the challenges and some future trends of CTF/graphene hybrids as advanced photocatalysts are also discussed from three aspects:catalysts design,performance stability and reaction mechanism.The approaches offer potential solutions to address the challenges of largescale production,catalyst activity and stability in the further research and development of new types of metal-free hybrid photocatalysts with high efficiency.展开更多
An alternative and fast method for the analysis of a mixture of nine triazines herbicides in soil is presented. The method is based on MAE （microwave-assisted extraction） of herbicides using ethyl acetate as extract...An alternative and fast method for the analysis of a mixture of nine triazines herbicides in soil is presented. The method is based on MAE （microwave-assisted extraction） of herbicides using ethyl acetate as extractant. The economy in the use of solvents coupled with the decrease in extraction time and lower power consumption make MAE a technique that meets the principles of green chemistry. MAE operational parameters, extraction time, mass of the sample and extraction temperature, were optimized by RSM （response surface methodology）. Determination of analytes was completed using gas chromatograph coupled to mass spectrometry detection. The selected triazines could be efficiently extracted by the solvent at 80 ℃ for 10 min, with 80% output of maximum power. When the optimized method was applied to analysis samples, the recoveries of analytes ranged from 81.8 to 106.0% and relative standard deviations were lower than 8.41%. The method is stable and reasonable, which can be used for the determination of ninetriazine herbicides residues in soil.展开更多
The main cash crop in Togo is cotton, with about 70% of agricultural exports. This crop is very dependent on the use of chemical inputs, in particular pesticides. Pesticides used in cotton farming in Togo include orga...The main cash crop in Togo is cotton, with about 70% of agricultural exports. This crop is very dependent on the use of chemical inputs, in particular pesticides. Pesticides used in cotton farming in Togo include organochlorines, triazines, organophosphates and pyrethroids. We conducted a study on the impact of these pesticide use, in particular organochlorines and triazines, on cotton farming soils. We chose the Plateaux region (southern Togo) as the study area because of its high cotton production. Analysis was carried out on crop soil samples at the 0 - 20 cm horizon. Several pesticide residues were found: simazine (0.051 to 0.103 μg/Kg soil);atrazine (0.149 to 0.197 μg/Kg soil);lindane (0.259 to 0.672 μg/Kg soil);β-endosulfan (1.37 to 5.727 μg/Kg soil);dieldrin (0.063 to 1.16 μg/Kg soil);endrin (0.512 μg/Kg soil), Heptachlor (0.489 to 1.243 μg/Kg soil);Heptachlor epoxide (0.928 to 1.633 μg/Kg soil);[2,4'DDT] (0.257 μg/Kg soil);[4,4'DDE] (0.262 μg/Kg soil). These results show pesticide contamination of cotton farming soils.展开更多
Substituted 2-azoniaallene salts 1 are strong bifunctional electrophiles, undergo cyclization reactions furnish many series of heterocyclic compounds, where reacted with p-tolyl urea, phenyl thiourea and thiosemicarba...Substituted 2-azoniaallene salts 1 are strong bifunctional electrophiles, undergo cyclization reactions furnish many series of heterocyclic compounds, where reacted with p-tolyl urea, phenyl thiourea and thiosemicarbazone derivatives to afford triazinium salts, and converted to corresponding free bases 3, 5, 7 under treatment with Na2CO3. While triazole derivatives 8 and 9 were obtained by the reaction 2-azoniaallene salts 1 with benzohydrazide and phenyl hydrazine, respectively. Benzoxazinium salts 10 and 11 were acquired when asymmetric 2-azoniaallene salt reacted in (1:1) ratio with p-cresol and 3-methyl-1-phenyl-5-pyrazolone, respectively. The reaction of 2-azoniaallene salt with malononitrile furnished the primidinium salt 12 which underwent neutralization with Na2CO3 followed by heterocyclization with hydrazine hydrate afforded the bicyclic compound 3-aminopyrazolo[3,4-d]pyrimidine 14, which is highly reactive for nucleophilic addition to phenyl isothiocyanate to furnish thiourea derivative 15. Moreover, 14 undergo condensation with aldehydes to give imine derivatives 16a,b. All free base compounds were screened for their antimicrobial activities.展开更多
Adsorption of atrazine, prometryne and prometon was determined on six soils with different physical and chemical properties. The adsorption isotherms of three herbicides could well fit Freundlich equation. On all of s...Adsorption of atrazine, prometryne and prometon was determined on six soils with different physical and chemical properties. The adsorption isotherms of three herbicides could well fit Freundlich equation. On all of six soils, adsorption of herbicides increased in the order: atrazine ≈prometon<prometryne. This order is quite the same to the calculation result of by means of excess thermodynamic properties of triazine. The Freundlich adsorption constants, K f, showed to have good correlation with organic matter(OM%) of soils for each of these herbicides, suggesting that OM is the main factor, which dominates in the adsorption process of these triazine herbicides.展开更多
Solar‐driven CO_(2)conversion to precious fossil fuels has been proved to become a potential way to decrease CO_(2)with producing renewable fuels,which mainly relies on photocatalysts with efficient charge separation...Solar‐driven CO_(2)conversion to precious fossil fuels has been proved to become a potential way to decrease CO_(2)with producing renewable fuels,which mainly relies on photocatalysts with efficient charge separation.In this work,a metal free heterostructure of covalent triazine framework(CTF)and graphite carbon nitride(g‐C_(3)N_(4),abbreviated as CN)is applied in the CO_(2)photoreduction for the first time.Detailed characterization methods such as photoluminescence(PL)and time‐resolved PL(TR‐PL)decay are utilized to reveal the photo‐induced carries separating process on g‐C_(3)N_(4)/CTF(CN/CTF)heterostructure.The introduced CTF demonstrated a great boosting photocatalytic activity for CN,bringing about the transform rates of CO_(2)to CO reaching 151.1μmol/(g·h)with a 30 h stabilization time,while negligible CH_(4)was detected.The optimal CN/CTF heterostructure could more efficiently separate charges with a lower probability of recombination under visible light irradiation,which made the photoreduction efficiency of CO_(2)to CO be 25.5 and 2.5 times higher than that of CTF and CN,respectively.This investigation is expected to offer a new thought for fabricating high‐efficiency photocatalyst without metal in solar‐energy‐driven CO_(2)reduction.展开更多
A new method for the synthesis of 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine (TAAT) is described. The key intermediate 4,4′,6,6′-tetra(azido)hydrazo-1,3,5-triazine (TAHT) was synthesized by nucleophilic substitution...A new method for the synthesis of 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine (TAAT) is described. The key intermediate 4,4′,6,6′-tetra(azido)hydrazo-1,3,5-triazine (TAHT) was synthesized by nucleophilic substitution in the case of sodium azide as nucleophile. N-Bromosuccinide (NBS) was used as oxidant to oxidize TAHT by a tractable operation under mild reaction condition. The target compound TAAT was obtained with a facile process and high overall yield of 81%. The structures of TAAT and its intermediates were identified by spectroscopic methods.展开更多
The photocatalytic production of syngas using a noble-metal-free catalytic system is a promising approach for renewable energy and environmental sustainability.In this study,we demonstrate an efficient catalytic syste...The photocatalytic production of syngas using a noble-metal-free catalytic system is a promising approach for renewable energy and environmental sustainability.In this study,we demonstrate an efficient catalytic system formed by integrating Co single sites,which act as the active sites,in covalent triazine frameworks(CTFs),which act as the photoabsorber,for the photocatalytic production of syngas from CO2 in aqueous solution.The enhanced light absorption of the CTFs,which contain intramolecular heterojunctions,in conjunction with 0.8 mmol L^‒1 of the Co complex enables excellent syngas production with a yield of 3303μmol g‒1(CO:H2=1.4:1)in 10 h,which is about three times greater than that achieved using CTF without a heterojunction.In the photocatalytic reaction,the coordinated single Co centers accept the photogenerated electrons from the CTF,and serve as active sites for CO2 conversion through an adsorption-activation-reaction mechanism.Theoretical calculations further reveal that the intramolecular heterojunctions highly promote photogenerated charge separation,thus boosting photocatalytic syngas production.This work reveals the promising potential of CTFs for single-metal-site-based photocatalysis.展开更多
2D MXenes are attractive for energy storage applications because of their high electronic conductivity.However,it is still highly challenging for improving the sluggish sodium(Na)-ion transport kinetics within the MXe...2D MXenes are attractive for energy storage applications because of their high electronic conductivity.However,it is still highly challenging for improving the sluggish sodium(Na)-ion transport kinetics within the MXenes interlayers.Herein,a novel nitrogen-doped Ti3C2Tx MXene was synthesized by introducing the in situ polymeric sodium dicyanamide(Na-dca)to tune the complex terminations and then utilized as intercalation-type pseudocapacitive anode of Na-ion capacitors(NICs).The Na-dca can intercalate into the interlayers of Ti3C2 Tx nanosheets and simultaneously form sodium tricyanomelaminate(Na3TCM)by the catalyst-free trimerization.The as-prepared Ti3C2Tx/Na3TCM exhibits a high N-doping of 5.6 at.%in the form of strong Ti-N bonding and stabilized triazine ring structure.Consequently,coupling Ti3C2Tx/Na3 TCM anode with different mass of activated carbon cathodes,the asymmetric MXene//carbon NICs are assembled.It is able to deliver high energy density(97.6 Wh kg-1),high power output(16.5 kW kg-1),and excellent cycling stability(≈82.6%capacitance retention after 8000 cycles).展开更多
基金Director of the project supported by National Natural Science foundation of China.
文摘3-Methylthio-5-hydroxy-1,2,4-triazine(1c)reacted with substituted benzenesulfonyl chloride to give 3-methylthio-5-oxy-1,2,4-triazin-6-yl pyridinium betaine(4)in anhydrous pyridine.But when NaOH/H_2O/CH_3COCH_3 or NaOH/CH_3OH were used as reactant and solvent,3-methylthio-4-substituted benzenesulfonyl-5-oxo-6-hydroxy-1,4,5,6-tetrahydro-1,2,4-triazine(6)or 1-tosyl-3-methylthio-5-oxo-6-methyloxy-1,4,5,6-tetrahydro-1,2,4-triazine(7)was obtained respectively.The above reactions show anomalous properties of nucleophilic attack on 6-carbon in 1,2,4-triazine ring.
基金This project has been supported by Sichuan Youth Foundation (Grant No. 05ZQ026-054) the Natural Science Foundation of Sichuan Education Bureau (Grant No. 2005A102).
文摘Density functional theory B3LYP is employed to obtain the optimized geometries of the ground state and interaction energy for triazines and water complexes. The results show that the 1,2,3-triazine-water, 1,2,4-triazine-water and 1,3,5-triazine-water complex on the ground state have Cs, Cs and C1 symmetry, and strong hydrogen bonding interaction with ?17.83, ?17.38 and ?13.55 kJ/mol after basis set superposition error and zero-point vibration energy correction, respectively, and large red-shift for the symmetric H─O stretching vibration frequencies forming N···H─O hydrogen bond in the triazines complex. The first singlet (n, π*) vertical excitation energy of the monomer and the hydrogen bonding complexes between triazines and water is investigated by time-dependent density functional theory.
基金the financial support by the National Natural Science Foundation of China(Nos.22205124,52172206)Natural Science Foundation of Shandong province(Nos.ZR2021QB070,ZR2023QB110)+2 种基金Basic Research Projects for the Pilot Project of Integrating Science and Education and Industry of Qilu University of Technology(Shandong Academy of Sciences)(Nos.2023PY024,2023PX108)Special Fund for Taishan Scholars Projectthe Development Plan of Youth Innovation Team in Colleges and Universities of Shandong Province。
文摘The high conductivity of electrocatalyst can eliminate the Schottky energy barrier at the interface of heterogeneous phases during an electrocatalytic reaction and accelerate the rapid electron transfer to the catalytic active center.Therefore,the electronic conductivity is a vital parameter for oxygen reduction reaction(ORR).Covalent triazine frameworks(CTFs)have shown great potential application as electrocatalysts in ORR with a merit of the diverse building blocks.However,the intrinsic low conductivity and high impedance of CTFs could be significant setbacks in electrocatalytic application.Herein,CTFs were constructed by introducing F and N co-modification for efficient 2e^(-)ORR.Compared with the pristine CTF,the co-presence of F,N could increase the conductivity obviously by 1000-fold.As a result,F-N-CTF exhibits enhanced catalytic performance of H_(2)O_(2)generation and selectivity towards reaction pathways.This work reveals the importance of conductivity optimization for CTFs and provides guidance for designing high conductivity non-metallic organic semiconductor catalysts for 2e^(-)ORR.
文摘Photoinduced molecular oxygen activation is crucial for artificial photosynthesis.However,metal-free semiconductor photocatalysts with high activation efficiency are still lacking up to now.Herein,two isomorphic tris(triazolo)triazine-based covalent organic frameworks were successfully constructed under solvothermal conditions.And they possess high crystallinity,inherent porosity with large surface area and good stability.Strong electron donor-acceptor skeletons expand the visible light harvesting,also facilitate the charge separation and thus lead to their superior activity of photoinduced molecular oxygen activation including photosynthesis of tetrahydroquinolines and hydrogen peroxide.This work provides a way to improve the efficiency of molecular oxygen activation through the rational design of COFs,and also opens new avenues for the construction of highly active and metal-free photocatalysts toward sustainable solar-to-chemical energy conversion.
基金supported by Natural Science Foundation of Gansu Province(23JRRA745)the Fundamental Research Funds for the Central Universities(lzujbky2021-sp55).
文摘Converting CO_(2)and water into valuable chemicals like plant do is considered a promising approach to address both environmental and energy issues.Taking inspiration from the structures of natural leaves,we designed and synthesized a novel copper-coordinated covalent triazine framework(CuCTF)supported by silicon nanowire arrays on wafer chip.This marks the first-ever application of such a hybrid material in the photoelectrocatalytic reduction of CO_(2)under mild conditions.The Si@CuCTF6 heterojunction has exhibited exceptional selectivity of 95.6%towards multicarbon products(C_(2+))and apparent quantum efficiency(AQE)of 0.89%for carbon-based products.The active sites of the catalysts are derived from the nitrogen atoms of unique triazine ring structure in the ordered porous framework and the abundant Cu-N coordination sites with bipyridine units.Furthermore,through DFT calculations and operando FTIR spectra analysis,we proposed a comprehensive mechanism for the photoelectrocatalytic CO_(2)reduction,confirming the existence of key intermediate species such as*CO_(2)-,*=C=O,*CHO and*CO-CHO etc.This work not only provides a new way to mimic photosynthesis of plant leaves but also gives a new opportunity to enter this research field in the future.
文摘FOR the purpose of finding novel antitumor and antivirus medicines and understanding themechanism of the metabolic process involved,several 6-azapurine derivatives were synthe-sized from 1,2,4-triazines.Mass spectrometry plays a key role in the structure
文摘As a continuation of the studies on the interference of metabolism of nucleic acids by 1,2,4-triazine derivatives, we have studied the preparation and chemical properties of a number of 1,2,4-triazines.
基金We thank the National Natural Science Foundation of China(Nos.21132005,21121004)the Ministry of Science and Technology of China(Nos.2011CB932501,2013CB834504)for financial support.
文摘A number of azacalix[2]pyrimidine[2]triazines were synthesized in moderate to good yields from both a step-wise fragment coupling approach and a one-pot reaction strategy starting from 4,6-diaminopyrimidines and cyanuric chloride.Nucleophilic aromatic substitution reaction of resulting dichloro-substituted azacalix[2]-pyrimidine[2]triazines with NH_(4)Cl led to the formation of NH_(2)-bearing azacalix[2]pyrimidine[2]triazine analogs.Azacalix[2]pyrimidine[2]triazines adopted symmetric 1,3-alternate conformations in solution while twisted 1,3-alternate conformations were observed in the solid state.In the presence of different additives during the growth of single crystals,azacalix[2]pyrimidine[2]triazines containing amino(-NH_(2))groups gave varied self-assembled structures due to the formation of different intermolecular hydrogen bond motifs.
基金Project supported by the National Natural Science Foundation of China （Nos. 20971041, 20803020, 20772027）, the Key Project of Chinese Ministry of Education （No. 210146） and Scientific Research Fund of Hunan Provincial Education Department （Nos. 09B032, 09C385, 09K081）.
文摘The 1,3-dipolar cycloaddition of an azomethine ylide generated by a decarboxylative route from sarcosine and acenaphthenequinone to 7-arylmethylidene-3-aryl-3,4-dihydro-2H-thiazolo[3,2-aJ[1,3,5]triazin-6（7H）-ones afforded novel dispiro[acenaphthylene-1,2’-pyrrolidine]-3＇,7″-[1,3]thiazolo[3,2-a][1,3,5]triazines in moderate yields. The structures of the products were determined and characterized thoroughly by NMR, MS, IR, elemental analysis and X-ray crystallographic analysis. The results of experiment indicated that this 1,3-dipolar cycloaddition proceeded with high stereoselectivity and regioselectivity.
基金supported by the National Natural Science Foundation of China(No.52273264)。
文摘Polymeric carbon nitride(PCN)has garnered increasing attention as a metal-free photocatalyst with a suitable band gap.In efforts to enhance its photocatalytic performance,researchers have examined various PCN materials,including poly(heptazine imide)(PHI)and poly(triazine imide)(PTI),two isomers within the PCN family that exhibit distinct and superior photocatalytic activity compared to other forms.The challenge,however,lies in the common practice among researchers to categorize PHI and PTI along with other PCN types under the overarching term“g-C_(3)N_(4),”which significantly impedes optimization efforts.The objective of this review is to provide comprehensive insights into the structural features,photoelectrochemical properties,and effective characterization methods employed for distinguishing between PHI and PTI materials.The review also summarizes various optimization strategies,such as crystallinity adjustments,defect engineering,morphology control,constructing heterojunction,and atomic-level metal loading dispersion,to elevate the photocatalytic activity of PHI and PTI,in addition to summarizing the history of carbon nitride development.Furthermore,this review highlights the primary applications of PHI and PTI,encompassing nitrogen fixation,biomass conversion,organic synthesis,CO_(2)reduction,pollutant degradation,H_(2)O_(2)production,and photocatalytic water splitting.Lastly,the prospects and challenges associated with further advancing PHI and PTI are thoroughly examined.
基金supported by the National Natural Science Foundation of China(Nos.22008185 and 22008188)the Shaanxi Provincial Key Research and Development Program(No.2022GY-166)+1 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.22JK0406)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.23JC033).
文摘Poly(triazine imide),as a kind of highly crystalline g-C_(3)N_(4),exhibits a promising potential for photo-catalytic hydrogen production,however,some drawbacks still limit its photocatalytic performance.The strategy of constructing S-scheme heterojunction with different semiconductor photocatalysts enables the effective separation of photogenerated electrons and holes,and the strong oxidative and reductive properties of the original photocatalysts could be retained,which will significantly improve the photo-catalytic activity.In this work,we synthesized the organic-organic S-scheme heterojunction between PTI and organic small molecule poly(barbituric acid)(PBA)by hydrogen bond self-assembly method,which results in a significant enhancement of photocatalytic H_(2)production activity.The H_(2)production rate of the optimum PBA/PTI-2 sample under visible light irradiation is about 0.92 mmol g^(-1),which is 5.5 times higher than that of PTI and 14.4 times higher than that of PBA.This excellent photocatalytic performance is attributed to the successful construction of S-scheme heterojunction between PTI and PBA,which ef-fectively accelerates carrier transport and spatial segregation by the formation of a built-in electric field and band bending at the interface.In addition,the S-scheme heterojunction could also reserve the maxi-mum redox capability and enhance the light absorption of the prepared photocatalytic system.This work provides a new strategy and understanding for the design and development of organic-organic S-scheme heterojunction photocatalysts.
文摘In recent years,photocatalysis with efficient,low-cost and stable metal-free catalysts is one of the most promising technologies for non-polluting energy production and resource-economic environment purifying.Benefiting from the molecularly precise backbones,regular and homogeneous porosity,lightelement composition,nitrogen-rich system with unique electronic band structure of two-dimensional(2D)covalent triazine framework(CTF),as well as the huge specific surface area,superior thermal conductivity,excellent carrier mobility and mechanical properties of 2D graphene,CTF/graphene hybrid-based photocatalysts show great application potential in the field of photocatalysis.In this review,the recent development in synthesis of CTF/graphene hybrid-based photocatalysts,and their applications in photocatalytic water splitting for hydrogen production and photocatalytic degradation of pollutants are summarized.Firstly,we briefly describe the molecular structures,physicochemical properties,and synthetic strategies for CTF/graphene hybrid-based photocatalysts including solution mixing method,in-situ polymerization method and sol-gel method.We further assess the impact of different preparation methods on the structure,morphology,and interacting model between CTF and graphene in CTF/graphene hybrids.Following the various preparation process for CTF/graphene hybrid-based photocatalysts,these methods are analyzed and compared regarding their merits and demerits.Secondly,the functions of CTF/graphene hybrid-based photocatalysts obtained from different synthesis approaches that enhance the catalytic activity for photocataLytic hydrogen evolution and photocatalytic degradation of pollutants are discussed from the three aspects of light harvesting,charge separation and transfer,and surface catalysis.Particular focus has been placed on the catalytic mechanisms of CTF/graphene hybridbased photocatalysts for enhanced photocatalytic hydrogen evolution and improved photocatalytic degradation of pollutants.Then the rational manipulation of selection and building units of CTF,connecting bonds between CTF and graphene,dimensions and pore structures of CTF/graphene hybrids in design of CTF/graphene hybrid-based photocatalysts is discussed,aiming to inspire critical thinking about the effective strategies for modification of photocatalysts rather than the development of novel materials.In the end,the challenges and some future trends of CTF/graphene hybrids as advanced photocatalysts are also discussed from three aspects:catalysts design,performance stability and reaction mechanism.The approaches offer potential solutions to address the challenges of largescale production,catalyst activity and stability in the further research and development of new types of metal-free hybrid photocatalysts with high efficiency.
文摘An alternative and fast method for the analysis of a mixture of nine triazines herbicides in soil is presented. The method is based on MAE （microwave-assisted extraction） of herbicides using ethyl acetate as extractant. The economy in the use of solvents coupled with the decrease in extraction time and lower power consumption make MAE a technique that meets the principles of green chemistry. MAE operational parameters, extraction time, mass of the sample and extraction temperature, were optimized by RSM （response surface methodology）. Determination of analytes was completed using gas chromatograph coupled to mass spectrometry detection. The selected triazines could be efficiently extracted by the solvent at 80 ℃ for 10 min, with 80% output of maximum power. When the optimized method was applied to analysis samples, the recoveries of analytes ranged from 81.8 to 106.0% and relative standard deviations were lower than 8.41%. The method is stable and reasonable, which can be used for the determination of ninetriazine herbicides residues in soil.
文摘The main cash crop in Togo is cotton, with about 70% of agricultural exports. This crop is very dependent on the use of chemical inputs, in particular pesticides. Pesticides used in cotton farming in Togo include organochlorines, triazines, organophosphates and pyrethroids. We conducted a study on the impact of these pesticide use, in particular organochlorines and triazines, on cotton farming soils. We chose the Plateaux region (southern Togo) as the study area because of its high cotton production. Analysis was carried out on crop soil samples at the 0 - 20 cm horizon. Several pesticide residues were found: simazine (0.051 to 0.103 μg/Kg soil);atrazine (0.149 to 0.197 μg/Kg soil);lindane (0.259 to 0.672 μg/Kg soil);β-endosulfan (1.37 to 5.727 μg/Kg soil);dieldrin (0.063 to 1.16 μg/Kg soil);endrin (0.512 μg/Kg soil), Heptachlor (0.489 to 1.243 μg/Kg soil);Heptachlor epoxide (0.928 to 1.633 μg/Kg soil);[2,4'DDT] (0.257 μg/Kg soil);[4,4'DDE] (0.262 μg/Kg soil). These results show pesticide contamination of cotton farming soils.
文摘Substituted 2-azoniaallene salts 1 are strong bifunctional electrophiles, undergo cyclization reactions furnish many series of heterocyclic compounds, where reacted with p-tolyl urea, phenyl thiourea and thiosemicarbazone derivatives to afford triazinium salts, and converted to corresponding free bases 3, 5, 7 under treatment with Na2CO3. While triazole derivatives 8 and 9 were obtained by the reaction 2-azoniaallene salts 1 with benzohydrazide and phenyl hydrazine, respectively. Benzoxazinium salts 10 and 11 were acquired when asymmetric 2-azoniaallene salt reacted in (1:1) ratio with p-cresol and 3-methyl-1-phenyl-5-pyrazolone, respectively. The reaction of 2-azoniaallene salt with malononitrile furnished the primidinium salt 12 which underwent neutralization with Na2CO3 followed by heterocyclization with hydrazine hydrate afforded the bicyclic compound 3-aminopyrazolo[3,4-d]pyrimidine 14, which is highly reactive for nucleophilic addition to phenyl isothiocyanate to furnish thiourea derivative 15. Moreover, 14 undergo condensation with aldehydes to give imine derivatives 16a,b. All free base compounds were screened for their antimicrobial activities.
文摘Adsorption of atrazine, prometryne and prometon was determined on six soils with different physical and chemical properties. The adsorption isotherms of three herbicides could well fit Freundlich equation. On all of six soils, adsorption of herbicides increased in the order: atrazine ≈prometon<prometryne. This order is quite the same to the calculation result of by means of excess thermodynamic properties of triazine. The Freundlich adsorption constants, K f, showed to have good correlation with organic matter(OM%) of soils for each of these herbicides, suggesting that OM is the main factor, which dominates in the adsorption process of these triazine herbicides.
文摘Solar‐driven CO_(2)conversion to precious fossil fuels has been proved to become a potential way to decrease CO_(2)with producing renewable fuels,which mainly relies on photocatalysts with efficient charge separation.In this work,a metal free heterostructure of covalent triazine framework(CTF)and graphite carbon nitride(g‐C_(3)N_(4),abbreviated as CN)is applied in the CO_(2)photoreduction for the first time.Detailed characterization methods such as photoluminescence(PL)and time‐resolved PL(TR‐PL)decay are utilized to reveal the photo‐induced carries separating process on g‐C_(3)N_(4)/CTF(CN/CTF)heterostructure.The introduced CTF demonstrated a great boosting photocatalytic activity for CN,bringing about the transform rates of CO_(2)to CO reaching 151.1μmol/(g·h)with a 30 h stabilization time,while negligible CH_(4)was detected.The optimal CN/CTF heterostructure could more efficiently separate charges with a lower probability of recombination under visible light irradiation,which made the photoreduction efficiency of CO_(2)to CO be 25.5 and 2.5 times higher than that of CTF and CN,respectively.This investigation is expected to offer a new thought for fabricating high‐efficiency photocatalyst without metal in solar‐energy‐driven CO_(2)reduction.
文摘A new method for the synthesis of 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine (TAAT) is described. The key intermediate 4,4′,6,6′-tetra(azido)hydrazo-1,3,5-triazine (TAHT) was synthesized by nucleophilic substitution in the case of sodium azide as nucleophile. N-Bromosuccinide (NBS) was used as oxidant to oxidize TAHT by a tractable operation under mild reaction condition. The target compound TAAT was obtained with a facile process and high overall yield of 81%. The structures of TAAT and its intermediates were identified by spectroscopic methods.
文摘The photocatalytic production of syngas using a noble-metal-free catalytic system is a promising approach for renewable energy and environmental sustainability.In this study,we demonstrate an efficient catalytic system formed by integrating Co single sites,which act as the active sites,in covalent triazine frameworks(CTFs),which act as the photoabsorber,for the photocatalytic production of syngas from CO2 in aqueous solution.The enhanced light absorption of the CTFs,which contain intramolecular heterojunctions,in conjunction with 0.8 mmol L^‒1 of the Co complex enables excellent syngas production with a yield of 3303μmol g‒1(CO:H2=1.4:1)in 10 h,which is about three times greater than that achieved using CTF without a heterojunction.In the photocatalytic reaction,the coordinated single Co centers accept the photogenerated electrons from the CTF,and serve as active sites for CO2 conversion through an adsorption-activation-reaction mechanism.Theoretical calculations further reveal that the intramolecular heterojunctions highly promote photogenerated charge separation,thus boosting photocatalytic syngas production.This work reveals the promising potential of CTFs for single-metal-site-based photocatalysis.
基金the support from the National Key Research and Development Program(No.2018YFB1107500)the National Natural Science Foundation of China(No.51503024)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.DUT17RC(3)003,DUT18RC(4)033)the National Natural Science Foundation of the Joint Fund Key Projects(No.U1663226)。
文摘2D MXenes are attractive for energy storage applications because of their high electronic conductivity.However,it is still highly challenging for improving the sluggish sodium(Na)-ion transport kinetics within the MXenes interlayers.Herein,a novel nitrogen-doped Ti3C2Tx MXene was synthesized by introducing the in situ polymeric sodium dicyanamide(Na-dca)to tune the complex terminations and then utilized as intercalation-type pseudocapacitive anode of Na-ion capacitors(NICs).The Na-dca can intercalate into the interlayers of Ti3C2 Tx nanosheets and simultaneously form sodium tricyanomelaminate(Na3TCM)by the catalyst-free trimerization.The as-prepared Ti3C2Tx/Na3TCM exhibits a high N-doping of 5.6 at.%in the form of strong Ti-N bonding and stabilized triazine ring structure.Consequently,coupling Ti3C2Tx/Na3 TCM anode with different mass of activated carbon cathodes,the asymmetric MXene//carbon NICs are assembled.It is able to deliver high energy density(97.6 Wh kg-1),high power output(16.5 kW kg-1),and excellent cycling stability(≈82.6%capacitance retention after 8000 cycles).
