Triazine Ring Research Articles

Comparison of conventional hydrothermal and microwave‐assisted synthesized g‐C3N4/MoS2 nanocomposite coated steel substrate by tribological measurement

AbstractMolybdenum disulfide is an effective solid lubricant, but it suffers from oxidation and moisture absorption issues, resulting in insufficient wear resistance and a shortened lifespan. This study introduces an innovative approach, integrating graphitic carbon nitride with molybdenum disulfide via advanced microwave‐assisted synthesis, offering precise control over synthesis parameters. The research assesses the tribological performance, comparing it with conventional hydrothermal synthesis. The study extensively investigates the morphology, microstructure, and tribology of a g‐C3N4/MoS2 nanocomposite created through novel microwave (g‐C3N4/MoS2‐MW) and hydrothermal techniques (g‐C3N4/MoS2‐HT). MoS2 exhibits a flower‐like structure, while graphitic carbon nitride has a layered structure, as confirmed by elemental analysis via energy‐dispersive X‐ray spectroscopy. X‐ray diffraction identifies g‐C3N4 peaks at 13.0° (100) and 27.5° (002) and hexagonal MoS2 peaks at 14° (002), 32.7° (100), 35.8° (102), and 58.3° (110). The Fourier‐transform infrared spectrum reveals peaks at 1237.4 and 808 cm−1 (aromatic and triazine ring breathing modes in g‐C3N4), 1407.1 and 1638.9 cm−1 (C=N and C−C heterocyclic structures), and 3432 cm−1 (vibrations due to −NH and −OH). The coefficients of friction for microwave‐assisted and traditional hydrothermal synthesized nanocomposites are 0.22 and 0.34, respectively. The wear depths are 98 microns and 141 microns, with a wear scar diameter of 2.87 mm for g‐C3N4/MoS2‐MW and 3.45 mm for g‐C3N4/MoS2‐HT, indicating superior lubrication with the microwave‐assisted coating.

A Versatile, Functional Group-Tolerant, and Bench-Stable Iron Precatalyst for Building Arene and Triazine Rings by [2+2+2] Cycloadditions.

We report an efficient iron-catalyzed cycloaddition procedure leading to the construction of (hetero)aromatic rings by alkyne [2+2+2] cycloisomerization. This method relies on the use of an air-stable (N,N)Fe(II) precursor easily prepared from a commercially available ligand derived from 1,10-phenanthroline, reduced in situ into a catalytically active non-innocent (N,N ⋅- )2 Fe(II) species. This system displays a large scope application, operates under mild conditions and at low catalytic charges (25 cycloadducts formed, up to 1.5 mol% catalyst). Moreover, this method also enables access to 29 cycloadducts by cross-cycloisomerization between 1,6- or 1,7-diynes and alkynes in near-equimolar conditions. 1,3,5-Triazines can also be prepared with this procedure starting from the corresponding cyanamides. Scale-up reactions and post-functionalization of several cycloadducts also show that this [2+2+2] cycloaddition can be used in multistep sequences.

Elaboration of a green and highly dispersible Co-MOFs induced Co-doped C3N5 photocatalyst: Applications and mechanistic insights into activated perxymonosulfate degradation of antibiotics

In recent years, metal-organic frameworks (MOFs) as metal-based carbon materials have been widely concerned with the application of activated perxymonosulfate(PMS) to degrade antibiotics. However, constructing MOFs-derived materials with excellent dispersion, highly exposed metal active sites, and environmental friendliness remains a challenge. This paper reports for the first time the in-situ formation of nitrogen-rich Co-doped C3N5 (Co-C3N5) materials using a cobalt-based metal-organic framework (Co-MOFs), which has highly dispersed metal sites that are conducive to the activation of PMS. The forbidden bandwidth value of Co-C3N5 photocatalyst is as low as ∼1.20 eV, which could completely degrade chlortetracycline hydrochloride (CTC) with the initial concentration of 30 mg/L within 6 min under a light source of 50 W LED lamp. The results indicate that efficient photoelectron separation and transport are key factors in the activation and degradation of CTC by PMS, involving both free radical and non-free radical degradation processes. Meanwhile, the skeletal structure of MOFs and the triazine ring of C3N5 were retained, enhancing the stability of the photocatalyst and reducing the leaching of cobalt Finally, the seed germination experiment of Chinese cabbage showed that the treated CTC could increase the root length of Chinese cabbage seedlings by 10.1∼42.9%, which proved that the materials had no toxic effect on environment and could provide carbon and nitrogen source for plant growth. Based on this, this study proposes a novel approach for the development of MOFs-derived carbon photocatalysts that exhibit excellent dispersion and highly exposed metal active sites.

Capture of CO2 by Melamine Derivatives: A DFT Study Combining the Relative Energy Gradient Method with an Interaction Energy Partitioning Scheme.

A theoretical study of the interaction between melamine and CO2 was carried out using density functional theory (DFT) with the B3LYP-D3(BJ)/aug-cc-pVTZ level of theory. The presence of anions interacting with melamine transforms the weakly bonded tetrel complexes into adducts. Thus, melamine acts as an FLP (frustrated Lewis pair) with acid groups (NHs as hydrogen bond donors) and a base group (N of the triazine ring). The application of the relative energy gradient formalism (REG) along the reaction coordinate has demonstrated that the ability of the melamine-anion systems to capture CO2 is linked to its capacity to polarize the CO2 molecule. These results have been confirmed by placing the melamine:CO2 complex in a uniform electric field with different strengths.

O-doped g-C3N4 prepared in pyridine for efficiently photocatalytic hydrogen production

ABSTRACT Oxygen-doped g-C3N4 with pyridine ring (POCN) was synthesized by easily thermal polymerization of urea, pyridine solution, and ammonium acetate to improve photocatalytic hydrogen production. The experimental results indicate that pyridine was incorporated into the tri-s-triazine structure of g-C3N4. The O atoms were modified to g-C3N4 by replacing the N atoms (C–N=C) of the triazine ring. The photocatalytic activity for the hydrogen production rate of optimized POCN was 1018 µmol g–1 h–1, approximately 30 times higher than that of bulk g-C3N4 (CN) under visible light irradiation (λ > 420 nm). The high stability of POCN was confirmed through cycling tests for 30-h, XRD patterns, and SEM images. The pyridine incorporation can significantly enhance surface charge transfer efficiency. The oxygen modification can greatly promote visible light absorption (600 nm) and photogenerated electron–hole pairs separation. This work provides a suitable strategy to synthesize g-C3N4 based on metal-free photocatalysts for highly efficient photocatalytic hydrogen generation performance.

Cyanuric Acid-Functionalized Perovskite Nanocrystals toward Low Interface Impedance, High Environmental Stability, and Superior Electrochemiluminescence.

Perovskite nanocrystals (PNs) have received much attention as luminescence materials in the field of electrochemiluminescence (ECL). However, as one key factor for determining the optoelectronic properties of the surface state of PNs, the surface passivation layer of PNs has enormous difficulty in simultaneously meeting the requirements of high ECL efficiency, conductivity, and stability. Herein, an effective surface modification strategy with cyanuric acid (CA) is used to solve such issue. As confirmed, the CA molecules are chemically anchored onto the surface of PNs via the Lewis interaction between π electrons of the triazine ring and the empty orbit of Pb2+. Benefiting from the above interaction, the electrochemical impedance of PNs is decreased greatly without the loss of light-emitting efficiency. Moreover, the stability of PNs under O2 exposure is improved by almost sixfold. These improvements are confirmed to be beneficial for enhancing the ECL behaviors of PNs under electrochemical operation. Upon cathode ECL driving conditions in aqueous media, the ECL intensity and efficiency of PNs are increased to 200 and 170%, respectively. This work provides a new modification strategy to holistically improve the ECL performance of PNs, which is instructive to exploring robust perovskite nanomaterials for electrochemical applications.

Preparation and thermostability of a Si/P/N synergistic flame retardant containing triazine ring structure for cotton fabrics

A new synergistic flame retardant named Bisiminopropyl trimethoxysilane-1,3,5-triazine-O-bicyclic pentaerythritol phosphate (BTPODE) was synthesized, which is a type of Si/P/N flame retardant. This was accomplished by grafting aminopropyl trimethoxysilane and bicyclic pentaerythritol phosphate onto a triazine ring structure, serving as an intermediate. The structure of BTPODE was determined using nuclear magnetic resonance (1H NMR, 13C NMR, and 31P NMR) and Fourier transform infrared spectroscopy (FT-IR). SEM was used to detect the surface morphology of cotton fabrics, which suggested that BTPODE had been resoundingly stick to cotton fabrics. The flame retardant properties of cotton fabrics were evaluated by measuring the limiting oxygen index (LOI) and conducting vertical flammability experiments. Cotton fabrics with a weight gain of 20.73 % achieved an LOI value of 32.5 %. Thermogravimetric (TG) experiments demonstrated the samples' good thermostability. Furthermore, under nitrogen conditions, the char residue of cotton fabric with a weight gain of 20.73 % was 36.85 %. The cone calorimetry test (CONE) showed a significant reduction in the TSP value, indicating a certain level of smoke suppression performance. Finally, based on the obtained experimental results, the fire-retardant mechanism principle of the flame retardant was deduced.

Covalent triazine reducing the defects by coordination roles and inhibiting I− migration by anion-π interaction for efficient perovskite solar cell

The grain boundary defects related non-radiative recombination, I− migration, and lead leakage problems are the foundational and fundamental aspects for the perovskite solar cells. Herein, covalent triazine frameworks (CTFs) are introduced into the perovskite film to address these problems. CTFs can passivate the uncoordinated Pb2+ defects at grain boundary and reduce the lead leakage based on the coordination interaction between nitrogen atoms in triazine ring and Pb2+. CTFs can also inhibit the I− migration and reduce the I− vacancy defects based on the anion-π interaction between electron-deficient triazine ring and I−. Benefited from the passivated grain boundary defects and inhibited I− migration by CTFs, the modified target device achieves a power conversion efficiency of 23.05 % with improved humidity stability and thermal stability. Therefore, this work lays the foundation for obtaining effective, stable, and environmentally friendly perovskite solar cells.

An unexpected tautomer: synthesis and crystal structure of N-[6-amino-4-(methylsulfanyl)-1,2-dihydro-1,3,5-triazin-2-ylidene]benzenesulfonamide

The title compound, C10H11N5O2S2, consists of an unexpected tautomer with a protonated nitrogen atom in the triazine ring and a formal exocyclic double bond C=N to the sulfonamide moiety. The ring angles at the unsubstituted nitrogen atoms are narrow, at 115.57 (12) and 115.19 (12)°, respectively, whereas the angle at the carbon atom between these N atoms is very wide, 127.97 (13)°. The interplanar angle between the two rings is 79.56 (5)°. The molecules are linked by three classical hydrogen bonds, forming a ribbon structure. There are also unusual linkages involving three short contacts (< 3 Å) from a sulfonamide oxygen atom to the C—NH—C part of a triazine ring.

A facile creation of hydrophilic-lipophilic-balanced covalent organic frameworks with mixed-mode retention mechanisms for multiple applications in liquid chromatography

Currently, high-performance liquid chromatographic separation materials that can provide multiple retention mechanisms are highly favored. Covalent organic frameworks (COFs) have undoubtedly demonstrated promising application prospects in chromatographic separation on account of excellent stability and porosity. Nevertheless, the utilization of COFs as liquid chromatographic fillers is still in the early stages of development. Especially, developing powerful COF@SiO2 with versatile separation capabilities still poses certain difficulties. Herein, a hydrophilic-lipophilic-balanced imine-linked COF was synthesized and in-situ growth on the amino-modified silica microsphere to obtain a multifunctional TAPT-TP-COF@SiO2 composite material. The synergistic effect of multiple functional groups including hydroxyl, amino, aldehyde, triazine and aromatic ring in the TAPT-TP-COF provided multiple retention mechanisms. The selection of 2,4,6-triformylphloroglucinol (TP) as the aldehyde counterpart improved the hydrophilic effect of the developed COF-based separation material, which enabled the effective separation of hydrophilic analytes (nucleosides, sulfonamides and vitamins). The novel TAPT-TP-COF@SiO2 column displayed typical reverse-phase and hydrophilic interaction chromatographic retention behavior. The successful applications demonstrated that TAPT-TP-COF@SiO2 had enormous potential for efficient liquid chromatographic analysis.

CREATION OF NOVEL GENERATION INHIBITORS WITH POTENTIAL EFFECT AGAINST ALZHEIMER'S DISEASE

Using fine organic synthesis methods and the latest capabilities of computational chemistry, for the first time, 2-(4-amino-6-phenyl-1,2,5,6-tetrahydro-1,3,5-triazine-2(1H)-ylidene)-malononitrile, which contains a triazine ring and various functional groups in the molecule, was synthesized without the presence of a catalyst through a one-step three-component reaction. Structural analyses were carried out using X-ray and Hirshfeld surface analysis, and it was determined that asymmetric molecules of 2-(4-amino-6-phenyl1,2,5,6-tetrahydro-1,3,5-triazine-2(1H)-ylidene)-malononitrile and a dimethylformamide solvent molecule in the asymmetric unit crystallize as a racemate in the monoclinic P21/c space group. These molecules exhibit stereochemical activity at the carbon atoms where the triazine rings are attached to the phenyl ring. For the first time, theoretical predictions using Density Functional Theory calculations for the synthesis reaction of tetrahydro-s-triazine via a one-step three-component condensation without a catalyst were experimentally tested. Comprehensive theoretical-experimental studies were conducted using quantum chemical calculations to simulate these chemical reactions, leading to significant results. The synthesis under milder conditions and atom-efficient methods obtained through computer simulations further enhances the importance of this work. This compound has shown high inhibitory effects on acetylcholinesterase in living organisms, and multiple analyses, including "molecular docking" studies, have revealed that in the future, representatives of these inhibitors with different functional groups could potentially be used as drugs against epilepsy, Alzheimer’s, and other neurological diseases.

Microenvironment modulation of Zr sites in covalent organic frameworks for low-pressure preparation of UHMWPE

Zr-TtDa catalyst with a triazine ring in ethylene polymerization forms hydrogen bonds with ethylene, enriching it around metal sites. This method produced high molecular weight linear polyethylene (Mw = 1.71 × 106 g mol−1) at a low pressure (5 bar).

Carbon pre-protected iron strategy to construct Fe, C-codoped g-C3N4 for effective photodegradation of organic pollutants via hole oxidation mechanism

Improving photocatalytic activity in graphitic carbon nitride (g-C3N4) by enhancing charge transfer and light absorption remains a challenge. Herein, iron-loaded carbon (FeC) was first prepared at low temperature, and then the Fe, C-codoped g-C3N4 (FeC–CN) was synthesized by high temperature thermal copolymerization of FeC with melamine. The carbon shell of FeC prevented the formation of iron oxide during high temperature thermal copolymerization, and Fe as electron channels existed in the interlayer, meanwhile, C atoms of FeC replaced part of the N atoms in the triazine ring. This designed structure facilitates in-plane and interlayer transfer of photogenerated carriers, as well as the separation of photogenerated carriers. Additionally, the UV–visible absorption spectra have demonstrated that the substitution of C atoms can greatly enhance visible light absorption. The catalyst exhibits significantly increased photocatalytic activity and excellent stability compared to g-C3N4. Interestingly, different from the reactive oxygen species-based g-C3N4 catalysis reaction, the degradation of organic pollutants was found to initiate from a hole-involved non-radical pathway. The increased electron transfer facilitates the reduction of O2 via a one-step two-electron pathway to generate hydrogen peroxide.

Carboxyl-functionalized two-dimensional MXene-Au nanocomposites were prepared as SERS substrates for the detection of melamine in dairy products.

In the present study, we address the limitations of conventional surface-enhanced Raman scattering (SERS) techniques for sensitive and stable detection of melamine in food products, especially dairy. To overcome these challenges, we developed a novel SERS-active substrate by incorporating gold nanoparticles (AuNPs) onto carboxyl-functionalized two-dimensional (2D) MXene material doped with nitrides, specifically Au-Ti2N-COOH. Our strategy leverages the unique physicochemical properties of MXene, a class of atomically thin, 2D transition metal carbides/nitrides, with tunable surface functionalities. By modifying the MXene surface with AuNPs and introducing carboxyl groups (-COOH), we successfully enhanced the interaction between the substrate and melamine molecules. The carboxyl groups form hydrogen bonds with the amino groups on the melamine's triazine ring, facilitating the adsorption of melamine molecules within the 'hotspot' regions responsible for SERS signal amplification. A series of characterization methods were used to confirm the successful synthesis of Au-Ti2N-COOH composites.Using Au-Ti2N-COOH as the SERS substrate, we detected melamine in spiked dairy product samples with significantly enhanced sensitivity and stability compared to nitride-doped MXene alone. The detection limit in liquid milk stands at 3.7008 μg kg-1, with spike recovery rates ranging from 99.84% to 107.55% and an approximate RSD of 5%. This work demonstrates the effectiveness of our approach in designing a label-free, rapid, and robust SERS platform for the accurate quantitation of melamine contamination in food, thereby mitigating health risks associated with melamine adulteration.

Highly efficient hydrogen production and selective CO2 reduction by the C3N5 photocatalyst using only visible light.

The production of energy sources by metal-free photocatalysts based on graphitic carbon nitride (g-C3N4) has garnered substantial attention. In this study, nitrogen-rich carbon nitride (C3N5) was successfully synthesized through the thermal polycondensation of 3-amino-1,2,4-triazole. The structural and physical characterization has suggested that a portion of the triazine rings, which constitute the structural framework of g-C3N4, may be substituted with five-membered rings in C3N5. Furthermore, the polymerization of C3N5 proceeded more extensively than that of g-C3N4 from melamine precursors. The increased nitrogen content in C3N5 resulted in a heightened number of π-electrons and a narrowed energy bandgap, with the potential of the valence band maximum being negatively shifted. Additionally, photocatalytic assessments encompassing nitro blue tetrazolium reduction, H2 production from triethanolamine aqueous solution, and CO2 reduction in the liquid phase were performed. All findings demonstrated that C3N5 exhibits significantly superior photocatalytic properties compared to g-C3N4. It is particularly noteworthy that C3N5 selectively generates methanol and H2 from oversaturated CO2 solutions under visible light irradiation, while g-C3N4 selectively generates formaldehyde. These outcomes strongly indicate that C3N5 serves as a metal-free, visible-light-responsive photocatalyst, capable of contributing to both the production of renewable energy sources and the reduction of greenhouse effect gases.

Electron Spin Resonance Spin Probe Technique for Investigating Non‐TEMPO Radicals Dispersed in Nanospaces of a Crystalline Zn Complex

An ESR spin probe technique with non‐TEMPO radicals, such as nitronyl nitroxide (NN), benzonitronyl nitroxide (BzNN), and iminonitroxide (IN) radicals, was used for a porous metal‐organic framework (MOF), [(ZnI2)3(TPT)2] (ZnTPT; TPT = tris(4‐pyridyl)‐1,3,5‐triazine), at room temperature. The principal values of g and hyperfine coupling (A) tensors estimated from spectral reproduction were different from those for organic matrices for some of these radicals. These results indicate that host‐guest interactions occur between the ZnTPT matrix and guest radicals. Thus, when using NN, BzNN, and IN radicals as spin probes for a porous MOF, the interaction between the metal atoms or organic ligands in host materials and guest radicals should be considered. The experimental ESR spectra for the derivatives of NN or BzNN radicals were reproduced only by the rigid‐limit component in the ESR time scale. However, those for the derivatives of IN radicals were approximately reproduced only by rotational diffusion around the z‐axis perpendicular to the plane in the IN group. Interestingly, this reproduction was not around the y‐axis of the principal axes of the g tensors, parallel to the molecular long axis, as previously observed in a few organic matrices. The IN radicals dispersed in the ZnTPT matrix are expected to be accommodated in cylindrical or pseudocylindrical nanospaces sandwiched by the pyridyl or triazine rings of TPT in ZnTPT. These findings show that the ESR spin probe technique using non‐TEMPO radicals can be used to investigate the chemical and biological structures of nanosized materials.

Emerging trends in the development and applications of triazine-based covalent organic polymers: a comprehensive review.

Owing to unique structural features, triazine-based covalent organic polymers (COPs) have attracted significant attention and emerged as novel catalysts or support materials for an array of applications. Typically formed by reacting triazine-based monomers or the in situ creation of triazine rings from nitrile monomers, these COPs possess 2D/3D meso/microporous structures held together via strong covalent linkages. The quest for efficient, stable and recyclable catalytic systems globally necessitates the need for a well-structured and comprehensive review summarizing the synthetic methodologies and applications of triazine-based COPs. This review explores the various synthetic routes and applications of these COPs in photocatalysis, heterogeneous catalysis, electrocatalysis, adsorption and sensing. By exploring the latest advancements and future directions, this review offers valuable insights into the synthesis and applications of triazine-based COPs.

Pseudo-covalent triazine frameworks for superior Li-S batteries

Rechargeable lithium-sulfur batteries are promising because of exceptional energy density and low cost. However, lithium-sulfur batteries suffer from severe polysulfide shuttle problems and sluggish conversion kinetics, which result in poor electrode reversibility and a limited lifespan. Herein, pseudo-covalent triazine frameworks integrated with conductive Ketjenblack have been desgined as sulfur hosts. The pseudo-covalent triazine frameworks, controllably synthesized via regulating on temperature and ratio between 1,4-dicyanobenzene precursor and ZnCl2, maintain highly porous triazine ring-lining skeleton with amorphous graphitic layers and abundant defects such as pyridine/pyrrole/quaternary-N atoms. Strong immobilization and fast catalytic conversion towards polysulfide are verified and theoretical explanations reveal these reaction sites are mostly occurring around triazine rings groups due to enhanced electron donating ability from N-atoms. Coin-type Li-S cells based on CTF@KB hosts exhibit outstanding rate performances (425.7 mAh/g at 10C) and lifespan (960.5 mAh/g mAh/g after 180 cycles), which are superior than previous reports. Pouch cells stress practicality of pseudo-covalent triazine frameworks (550.6 mAh/g after 60 cycles).

Development of a multistep-GRRM/MC/MD simulation method for the formation of crosslinked network structures via multistep reversible reaction pathways

Molecular dynamics (MD) simulations offer insights into high-performance polymer attributes and assist in creating novel materials. However, simulating cyanate resin systems remains a challenge due to the complexities of triazine ring formation. While earlier research efforts have been made, a consistent procedure for analyzing cyanate resins remains elusive. This research introduces a precise and replicable method for modeling cyanate resin systems, focusing on triazine ring formation processes. The technique combines a crosslinking method, a unique ring-formation algorithm, and a protocol for MD simulations. Using Bisphenol A dicyanate ester (BPACN) as the monomer, a polymer model is created. Predicted attributes like a glass transition temperature of 298.7 ± 3.7 °C and a Young's modulus of 2.95 ± 0.22 GPa align well with experimental data. This innovative method offers a blueprint for other triazine ring formations.

Donor-Acceptor Conjugated Acetylenic Polymers for High-Performance Bifunctional Photoelectrodes.

Due to the drastic required thermodynamical requirements, a photoelectrode material that can function as both a photocathode and a photoanode remains elusive. In this work, we demonstrate for the first time that, under simulated solar light and without co-catalysts, donor-acceptor conjugated acetylenic polymers (CAPs) exhibit both impressive oxygen evolution (OER) and hydrogen evolution (HER) photocurrents in alkaline and neutral medium, respectively. In particular, poly(2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine) (pTET) provides a benchmark OER photocurrent density of ~200 μA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) at pH 13 and a remarkable HER photocurrent density of ~190 μA cm-2 at 0.3 V vs. RHE at pH 6.8. By combining theoretical investigations and electrochemical-operando Resonance Raman spectroscopy, we show that the OER proceeds with two different mechanisms, with the electron-depleted triple bonds acting as single-site OER in combination with the C4-C5 atoms of the phenyl rings as dual sites. The HER, instead, occurs via an electron transfer from the tri-acetylenic linkages to the triazine rings, which act as the HER active sites. This work represents a novel application of organic-based materials and contributes to the development of high-performance photoelectrochemical catalysts for the solar fuels' generation.