Triazine Moiety Research Articles

Unconventional Three-Armed Luminogens Exhibiting Both Aggregation-Induced Emission and Thermally Activated Delayed Fluorescence Resulting in High-Performing Solution-Processed Organic Light-Emitting Diodes.

In this work, three-armed luminogens IAcTr-out and IAcTr-in were synthesized and used as emitters bearing triazine and indenoacridine moieties in thermally activated delayed fluorescence organic light-emitting diodes (OLEDs). These molecules could form a uniform thin film via the solution process and also allowed the subsequent deposition of an electron transporting layer either by vacuum deposition or by an all-solution coating method. Intriguingly, the new luminogens displayed aggregation-induced emission (AIE), which is a unique photophysical phenomenon. As a nondoped emitting layer (EML), IAcTr-in showed external quantum efficiencies (EQEs) of 11.8% for the hybrid-solution processed OLED and 10.9% for the all-solution processed OLED with a low efficiency roll-off. This was evident by the higher photoluminescence quantum yield and higher rate constant of reverse intersystem crossing of IAcTr-in, as compared to IAcTr-out. These AIE luminogens were used as dopants and mixed with the well-known host material 1,3-bis( N-carbazolyl)benzene (mCP) to produce a high-efficiency OLED with a two-component EML. The maximum EQE of 17.5% was obtained when using EML with IAcTr-out doping (25 wt %) into mCP, and the OLED with EML bearing IAcTr-in and mCP showed a higher maximum EQE of 18.4% as in the case of the nondoped EML-based device.

Carbazole-decorated covalent triazine frameworks: Novel nonmetal catalysts for carbon dioxide fixation and oxygen reduction reaction

Task-specific carbazole-based covalent triazine frameworks (CTF-CSUs) have been designed and prepared. The obtained materials could serve as excellent catalysts for both CO2 chemical fixation and oxygen reduction reaction (ORR). Results shown that using CTF-CSUs as catalysts, the cycloaddition reactions between CO2 and epoxides were readily achieved with extremely high yields (99%) under mild conditions (0.1 MPa, 25 °C). The catalysts could be reused for five times without any obvious loss of catalytic activity. In addition, the as-made carbazole-containing CTFs catalysts delivered attractive ORR activity, superior durability and methanol tolerance relative to commercially available Pt/C reference electrocatalyst (E-TEK). Rich N contents (15.33 wt%) and large surface areas (982 m2 g−1) combining abundant mesopores favor a combination of two-electron and four-electron reduction pathway under alkaline condition. All these attracting characteristics were attributed to their unique structures and strong synergistic effect between carbazole and triazine moieties.

Branched phenyl‐s‐triazine moieties to enhance thermal properties of phthalonitrile thermosets

AbstractHeat‐resistant materials have made tremendous progress in marine, aerospace and microelectronic fields. Herein, a new class of phthalonitrile resins, branched poly(biphenyl ether triphenyl‐s‐triazine) phthalonitriles, were successfully synthesized via a two‐step, one‐pot reaction, on the basis of 2,4,6‐tris(4‐fluorophenyl)‐1,3,5‐triazine and 4,4′‐biphenol. 4,4′‐Diaminodiphenylsulfone was employed to facilitate the curing reaction, and successful realization of curing behavior was concluded from rheological and differential scanning calorimetric studies, indicating the obtained resins possess favorable processability. The relationship between concentration of reactants and properties of the resins was systematically studied. After thermal curing, the E‐glass fiber‐reinforced composite, prepared with a concentration of reactants of 0.15 g mL−1, shows an admirable glass transition temperature of 480 °C and commendable thermal stability with 5% weight loss temperature in nitrogen of 563 °C, suggesting that the improvement of the thermal properties stems from the branched structure and the phenyl‐s‐triazine units. © 2017 Society of Chemical Industry

Hindered C[sbnd]N bond rotation in triazinyl dithiocarbamates

The substituent and solvent effects on the rotation around a CN amide bond were studied for a series of triazine dibenzylcarbamodithioates. The Gibbs free energies (ΔG‡) were measured to be 16–18 kcal/mol in DMSO-d6 and toluene-d8 using variable-temperature nuclear magnetic resonance (VT-1H NMR) spectroscopy. Density functional theory (DFT) calculations reproduced the experimental observations with various substituents, as well as solvents. From the detailed analysis of the DFT results, we found that the electron donating dibenzyl amine group increased the electron population on the triazinyl ring, which decreased the rotational barrier of the CN bond in the dithiocarbamate group attached to the triazinyl ring. The higher electron population on the triazine moiety stabilizes the partial double bond character of the SC bond, which competitively excludes the double bond character of the CN bond. Therefore, the rotational dynamics of the CN bond in dithiocarbamates can be a sensitive probe to small differences in the electron population of substituents on sulfur.

Chemically Activated Covalent Triazine Frameworks with Enhanced Textural Properties for High Capacity Gas Storage.

Chemical activation of porous/nonporous materials to achieve high surface area sorbents with enhanced textural properties is a very promising strategy. The chemical activation using KOH, however, could lead to broad distribution of pores originating from the simultaneous pore deepening and widening pathways. Accordingly, establishing correlation between the chemical/textural properties of starting porous/nonporous materials and various pore formation mechanisms is quite critical to realize superior porosity and gas uptake properties. Here, we show that the chemical and textural properties of starting porous organic polymers, that is, covalent triazine frameworks (CTF), have profound effect on the resulting porosity of the frameworks. The chemical activation of microporous CTF-1 using KOH at 700 °C enabled the preparation of chemically activated CTF-1, caCTF-1-700, which predominantly showed pore deepening, leading to an increased surface area of 2367 m2 g-1 and significantly enhanced gas adsorption properties with CO2 uptake capacities up to 6.0 mmol g-1 at 1 bar and 1.45 mmol g-1 at 0.15 bar and 273 K along with a isosteric heats of adsorption (Qst) of 30.6 kJ mol-1. In addition, a remarkable H2 uptake capacity of 2.46 and 1.66 wt % at 77 and 87 K, 1 bar along with the Qst value of 10.95 kJ mol-1 at zero coverage was also observed for the caCTF-1-700. Notably, the activation of mesoporous CTF-2 under the same conditions was accompanied by a decrease in its surface area and also in the conversion of mesopores into the micropores, thus leading to a pore deepening/narrowing rather than widening. We attributed this result to the presence of reactive weak spots, triazine moieties, for the chemical activation reaction within the CTF backbone. These results collectively suggest the critical role of chemical and pore characteristics of porous organic polymers in chemical activation to realize solid-sorbents for high capacity gas storage applications.

Dual-sensitive charge-conversional polymeric prodrug for efficient co-delivery of demethylcantharidin and doxorubicin

Polypyridyl based on triazine and pyrazine rings with Pt4+, including 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPT, L1) and 2,3,5,6-tetra(2-pyridyl)-1,4-triazine (TPP, L2), was reported. [Pt34+ (TPT)2Cl8]Cl4·2H2O (1) and [Pt4+(TPP)Cl3]Cl·3H2O (2) were synthesized and characterized. Comparative studies of the solvothermal of Pt4+ complexes and the stability studies of triazine and pyrazine moieties were investigated. Pt2+ complex, [PtII(bpca)Cl], resulted from the metal-promoted solvolysis of L1 to bis-(2-pyridylcarbonyl) amide anion (bpca) and 2-picolinamide, gives yellow single crystal, C12H8ClN3O2Pt (3). The effect of ionic radii of the metal ions has a vital role in solvolysis process. The single crystal shows a square-planar around the Pt2+ ion (3). Crystal data of 3: space group; a = 7.5263 (2) b = 14.1846 (4) c = 22.6884 (7) Å, α = β = γ = 90°, V = 2422.16 (12) Å3, Z = 8. The DFT parameters were calculated to confirm the geometry of complexes. Anticancer activity of complexes was measured.

An intelligent doxorubicin prodrug with GRP78 recognition and sequential targeting ability to tumor cell membrane and nucleus

Polypyridyl based on triazine and pyrazine rings with Pt4+, including 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPT, L1) and 2,3,5,6-tetra(2-pyridyl)-1,4-triazine (TPP, L2), was reported. [Pt34+ (TPT)2Cl8]Cl4·2H2O (1) and [Pt4+(TPP)Cl3]Cl·3H2O (2) were synthesized and characterized. Comparative studies of the solvothermal of Pt4+ complexes and the stability studies of triazine and pyrazine moieties were investigated. Pt2+ complex, [PtII(bpca)Cl], resulted from the metal-promoted solvolysis of L1 to bis-(2-pyridylcarbonyl) amide anion (bpca) and 2-picolinamide, gives yellow single crystal, C12H8ClN3O2Pt (3). The effect of ionic radii of the metal ions has a vital role in solvolysis process. The single crystal shows a square-planar around the Pt2+ ion (3). Crystal data of 3: space group; a = 7.5263 (2) b = 14.1846 (4) c = 22.6884 (7) Å, α = β = γ = 90°, V = 2422.16 (12) Å3, Z = 8. The DFT parameters were calculated to confirm the geometry of complexes. Anticancer activity of complexes was measured.

Triazines – A comprehensive review of their synthesis and diverse biological importance

Triazine is a heterocyclic aromatic ring structure, with three isomers distinguished by positions of their nitrogen atoms. 1,2,3-triazine derivatives like tubercidin, toyocamycin, sangivamycin, 2-azaadenosine and 2-aza-2-desamino-5,8-dideazafolic acid are the important active moieties in pharmaceutical field while 6-azacytosine, 6-azauracil, azaribine, tirapazamine, dihydromethyl furalazine, vardenafil, apazone, lamotrigine, ceftriaxone, pymetrozine, fervenulin (planomycin), reumycin and toxoflavin (panthothricin) are 1,2,4-triazine moieties used in clinical practices. The triazine ring structure is also found in naturally occurring antibiotics like fervenulin, reumycin and toxoflavin. 1,3,5-Triazine isomer or s-triazine is an oldest known organic compound, broadly used as a lead structure in ammeline, aceto-guanide, acetoguanamine, cyanuric acid and melamine. Some s-triazine containing drugs are hexamethylmelamine (altretamine), 2-amino-4-morpholino-s-triazine, hydroxymethyl-pentamethyl melamine, triethylenemelamine (tretamine), dioxadet, irsogladine, cycloguanil, almitrine, S9788 and DW1865. Triazines have a high significance in the field of pharmaceutical chemistry with wide-spectrum of pharmacological activities so useful for design and formation of novel drugs. Some triazine analogues are recently screened in clinical trials which may lead to potent type drugs with no side effects as presently available pharmacological agents. This review outlines the biological importance and synthesis of various types of triazine derivatives from various heterocyclic and drugs containing triazine moiety.

Synthesis and Structure of a New Class of Fused Heterocycle with 8,9-Dihydro-pyridazino[1,2,4]triazine Skeleton

The synthesis and X-ray crystal structure of a new class of fused heterocycle with 8,9-dihydro-pyridazino[1,2,4]triazine type 2 is reported. The synthesis is facile and efficient and, the structure of compounds was proven by elemental and spectral analysis, the X-ray spectra including (for 2b). The compound crystallizes in the space group P21/N (monoclinic) with a = 9.0077(2) �, b = 10.20019(18) �, c = 14.0099(3) �, a= 90�, b = 89.768(2)�, g= 90�, V= 1287.22(5) and Z = 4. Accurate molecular parameters for the heterocyclic system were obtained from intensity data collected at 200(14) K. The molecule 8,9-dihydro-pyridazino[1,2,4]triazine type 2 is a noncoplanar bicyclic fused system, with an envelope shape onto the triazine moiety, the C12 carbon being out of plane. The methyl group from the C12 carbon it is almost perpendicular on the triazine plane. We also notice a rather powerful hydrogen bond between hydrogen atom from N1 and the oxygen from the C11=O1 carbonyl group.

Triazole/Triazine-Functionalized Mesoporous Silica As a Hybrid Material Support for Palladium Nanocatalyst.

Noble and precious metal catalysts are sought for their remarkable efficiency in catalyzing numerous reactions in heterogeneous phase. However, they are costly and require the development of high-surface-area supports that favor their strong immobilization, dispersion, and stability. Toward this end, mesoporous silica-based materials can be regarded as unique supports for nanometric-sized noble metal catalysts provided they are functionalized with appropriate ligands. In this work, mesoporous silica SBA-15 was prepared and modified with 3-azidopropyltriethoxysilane and then clicked with alkyne derivatives of 1,3,5-triazine complex ligand. The resulting hybrid material contains triazole and triazine moieties covalently bound to the mesoporous silica network. The triazole/triazine minidendron was immobilized through a 1,3-dipolar cycloaddition click reaction, which was monitored by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The heterocyclic ligand-functionalized SBA-15 material served as a hybrid reactive platform for in situ deposition of palladium nanoparticles whose size is 3.154 ± 0.49 nm as assessed by X-ray diffraction and confirmed by transmission electron microscopy. The catalytic performance of the final palladium-decorated hybrid triazole/triazine-functionalized SBA-15 support was evaluated in the model reduction of 4-nitrophenol to 4-aminophenol by catalytic hydrogenation and stoichiometric reduction. Excellent catalytic performances were achieved, with reduction rate constant (Kapp) of 16.8 × 10-3 s-1 for this model reaction. Moreover, the hybrid catalyst can be produced in high yield and recycled.

Multiple spectroscopic analyses reveal the fate and metabolism of sulfamide herbicide triafamone in agricultural environments

Triafamone, a sulfamide herbicide, has been extensively utilized for weed control in rice paddies in Asia. However, its fate and transformation in the environment have not been established. Through a rice paddy microcosm-based simulation trial combined with multiple spectroscopic analyses, we isolated and identified three novel metabolites of triafamone, including hydroxyl triafamone (HTA), hydroxyl triafamone glycoside (HTAG), and oxazolidinedione triafamone (OTA). When triafamone was applied to rice paddies at a concentration of 34.2 g active ingredient/ha, this was predominantly distributed in the paddy soil and water, and then rapidly dissipated in accordance with the first-order rate model, with half-lives of 4.3–11.0 days. As the main transformation pathway, triafamone was assimilated by the rice plants and was detoxified into HTAG, whereas the rest was reduced into HTA with subsequent formation of OTA. At the senescence stage, brown rice had incurred triafamone at a concentration of 0.0016 mg/kg, but the hazard quotient was <1, suggesting that long-term consumption of the triafamone-containing brown rice is relatively safe. The findings of the present study indicate that triafamone is actively metabolized in the agricultural environment, and elucidation of the link between environmental exposure to these triazine or oxazolidinedione moieties that contain metabolites and their potential impacts is warranted.

1,2,4-Triazine-Modified 2'-Deoxyuridine Triphosphate for Efficient Bioorthogonal Fluorescent Labeling of DNA.

In order to establish the Diels-Alder reaction with inverse electron demand for postsynthetic DNA modification, a 1,2,4-triazine-modified 2'-deoxyuridine triphosphate was synthesized. The bioorthogonally reactive 1,2,4-triazine group was attached at the 5-position of 2'-deoxyuridine by a flexible alkyl linker to facilitate its acceptance by DNA polymerases. The screening of four DNA polymerases showed successful primer extensions, using a mixture of dATP, dGTP, dCTP, and the modified 2'-deoxyuridine triphosphate, by using KOD XL or Vent polymerase. The triazine moiety was stable under the conditions of primer extension, which was evidenced by labeling with a BCN-modified rhodamine at room temperature in yields of up to 82 %. Two or three modified bases could be incorporated in quantitative yields when the modification sites were separated by three base pairs. These results establish the 1,2,4-triazene group as a bioorthogonally reactive moiety in DNA, thereby replacing the problematic 1,2,4,5-tetrazine for postsynthetic labeling by the Diels-Alder reaction with inverse electron demand.

Thermally stable bipolar host materials for high efficiency phosphorescent green and blue organic light-emitting diodes

Two bipolar host materials H1 (N-linked carbazole) and H2 (C-3-linked carbazole) via changing the substitution position of triazine and carbazole moieties are reported. Their structural and physical properties were fully characterized. The thermal analysis demonstrated that both H1 and H2 are of high thermal stability. The triplet energy levels of H1 and H2 were determined to be 2.64 and 2.7 eV, respectively. Both green and blue OLEDs with H1 and H2 acting as host materials were fabricated to investigate their performances in PHOLED. The green PHOLED based on H1 exhibits the best performance with the maximum current efficiency, maximum power efficiency and maximum brightness of 51.7 cd/A, 37.8 lm/W and 132800 cd/m2, respectively, while the blue PHOLED based on H2 shows the best performance with the maximum current efficiency, maximum power efficiency and maximum brightness of 21.6 cd/A, 17.2 lm/W and 16640 cd/m2, respectively. The characteristic measurements of OLED devices reveal that both H1 and H2 are promising host materials for practical application. By comparing the commercial host materials of 4,4’-bis(carbazol-9-yl)biphenyl (CBP) and N,N-dicarbazoyl-3,5-benzene (mCP), the power efficiencies of green and blue PHOLED were boosted by 22.3% and 75.5%, respectively.

Formation of planarized intramolecular charge-transfer state in dichlorotriazinyl-pyrene fluorescent probe: TD-DFT and resonance Raman study

This study is focused on explanation of the remarkable photophysical behaviour of the 1-(4,6-dichloro-1,3,5-triazin-2-yl)-pyrene (PyTC2) compound which has been introduced as a fluorescent polarity probe. This compound exhibits large solvatochromic red-shift of fluorescence emission band while maintaining high fluorescence quantum yield and monoexponential decay kinetics throughout the whole solvent polarity scale. As the semi-empirical calculations reported in the original paper have not revealed any excited state possessing a high dipole moment, it has been suggested that the red-shift originates from planarization of the emitting excited state in polar solvents in contrast to unchanged twisted geometry in non-polar solvents. However, both the extent of the red-shift and the disappearance of the vibronic structure in polar solvents indicate that the emission originates from an excited state with high dipole moment and that the semi-empirical methods may not be sufficient to describe the emitting state of this molecule correctly. Thus, we have performed TD-DFT calculations including the potential energy surface scans. According to these calculations and scans, the emission takes place from a planarized intramolecular charge-transfer (ICT) state. This is in good agreement with all aspects of the observed fluorescence behaviour of PyTC2. Independent experimental evidence for the ICT has been provided by analysis of resonance Raman intensities where bands corresponding to enhanced normal modes residing on triazine and the stretching mode between pyrene and triazine moieties have been identified. The formation of the photoinduced ICT together with easy and inexpensive preparation make this compound and its derivatives candidate as push-pull building blocks for the design of advanced functional materials.

Silica gel microspheres decorated with covalent triazine-based frameworks as an improved stationary phase for high performance liquid chromatography

A new stationary phase for high performance liquid chromatography (HPLC) applications based on silica gel microspheres decorated with covalent triazine-based frameworks (CTF–SiO2) composite has been reported here. In this new hybrid material, sheet-like covalent triazine-based frameworks (CTF) were grown onto the supporting silica spheres, in order to achieve improved chromatographic separation and selectivity. The new material was characterized by infrared spectroscopy, elemental analysis and thermogravimetric analysis. The chromatographic performance and retention mechanism of the new stationary phase were investigated in reversed-phase mode and compared against standard C18 and cyano-modified silica (CN–SiO2) columns. A variety of different probe molecules were analyzed, including mono-substituted benzenes, polycyclic aromatic hydrocarbons, phenols, anilines and bases. The synergism of triazine and aromatic moieties provided several different retention mechanisms, thus improving the selectivity in the CTF–SiO2 composite. The good column packing properties of the uniform silica microspheres combined with the separation ability of the CTF frameworks make the new CTF–SiO2 material a potentially useful stationary phase for the analysis of complex samples.

Pd catalyzed couplings of “superactive esters” and terminal alkynes: Application to flavones and γ-benzopyranones construction

Lewis base, N-methylmorpholine (NMM) accelerated Pd-catalyzed Sonogashira coupling of steric hindered super active esters, 1a–1e, and terminal alkynes. This approach provided an efficient synthetic protocol for a broad array of acylated o-alkynoylphenols compounds, 3a–3e, under moderate conditions. The mechanistic study clearly demonstrated that NNM stabilized the catalytic palladium species, and accelerated the leaving of triazine moiety during the catalytic cycle of the cross-coupling reactions. In addition, piperazine was found to efficiently catalyze the 6-endo cyclization of acylated o-alkynoylphenols, which achieved the diversity oriented synthesis of γ-benzopyranones, 4aa–4eg, with 93–99% yields.

Engineering the Interconnecting Position of Star-Shaped Donor-π-Acceptor Molecules Based on Triazine, Spirofluorene, and Triphenylamine Moieties for Color Tuning from Deep Blue to Green.

Pi-conjugated organic molecules featuring the donor-bridge-acceptor (D-π-A) structure have been widely used in semiconducting materials owing to their rigid structure, good thermal stability, excellent charge transfer, and high emission efficiency. To investigate the effect of the D-π-A molecular structure on the photophysical properties, in this contribution, three star-shaped D-π-A isomers based on the 2,4,6-triphenyl-1,3,5-triazine, spirofluorene, and triphenylamine moieties, that is, p-TFTPA, mp-TFTPA, and m-TFTPA, were synthesized by elaborately engineering the interconnecting position in the building-block units. The optophysical properties of these compounds were systematically explored by experiments and theory calculations. Definitively, changing the interconnecting position in these molecules played a significant role in the degree of π conjugation, which resulted in tunable emission colors from deep blue to green. Moreover, these isomers were employed as emissive dopants in organic light-emitting diodes. The highest external quantum efficiency of 2.3 % and current efficiency of 6.2 cd A(-1) were achieved by using the p-TFTPA based device. This research demonstrates a feasible way to realize blue emitters by engineering D-π-A conjugation.

Synthesis, structural characterization, thermal analysis, and DFT calculation of a novel zinc (II)-trifluoro-β-diketonate 3D supramolecular nano organic-inorganic compound with 1,3,5-triazine derivative

A sonochemical method was used to synthesize a novel nano-structure of a zinc(II) organic-inorganic compound [Zn(dapt)2(ttfa)2] (1) [dapt = 2,4-diamino-6-phenyl-1,3,5-triazine and ttfa = 2-thenoyltrifluoroacetonate]. The new nanostructure was characterized by scanning electron microscopy, X-ray powder diffraction, elemental analysis, and thermal analysis. The single-crystal X-ray structure shows that 1 is a discrete coordination compound. Strong intra- and intermolecular hydrogen bonds are observed in the structure with the latter forming chains of molecules running parallel to (110). The chains are further extended into a three-dimensional supramolecular structure by intermolecular CF⋯π interactions between trifluoromethyl and triazine moieties. The coordination number of the zinc(II) ion is six (ZnN2O4), and the coordination sphere is tetragonally elongated octahedral. The structure of the title complex was optimized by DFT calculations.

Novel Nitrogen and Sulfur Rich Hyper-Cross-Linked Microporous Poly-Triazine-Thiophene Copolymer for Superior CO2 Capture

A novel synthetic strategy has been developed for the preparation of hyper-cross-linked microporous copolymers, HMC-1, HMC-2, and HMC-3, by using 2,4,6-tri(thiophen-2-yl)-1,3,5-triazine and thiophene monomers in their different molar ratios in the presence of anhydrous FeCl3 in chloroform under solvothermal conditions at 150 °C. These polymers are highly porous and robust materials, exhibiting very high BET surface areas and supermicroporosity. The presence of triazine and thiophene moieties within the copolymer network increases the electron donating basic N and S sites in the porous frameworks. Thus, these porous polymers displayed efficient adsorption of Lewis acidic CO2 molecules and showed good CO2/N2 adsorption selectivity. The maximum CO2 uptake of 14.2 mmol g–1 at 273 K under 3 bar pressure has been observed.

The influence of torsion on excimer formation in bipolar host materials for blue phosphorescent OLEDs.

We present a combined detailed spectroscopic and quantum chemical study on the bipolar host materials BPTRZ and MBPTRZ in solution and in neat film. In the two compounds, the hole transporting carbazole is separated from the electron transporting triazine moiety by a fully aromatic but non-conjugated meta-linked biphenyl unit. The two materials differ by an additional steric twist at the biphenyl in MBPTRZ, which is achieved by methyl-substitution in 2- and 2'-position of the biphenyl. We find that while the twist shifts the triplet state in MBPTRZ to higher energies (3.0 eV in solution) compared to BPTRZ (2.8 eV in solution), this also localizes electron density on the carbazole moiety, leading to excimer formation in neat films.