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Using first-principles calculations, the structural, electronic, and optical properties of CO2, CO, N2O, CH4, H2, N2, O2, NH3, acetone, and ethanol molecules adsorbed on a diazine monolayer were studied to develop the application potential of the diazine monolayer as a room-temperature gas sensor for detecting acetone, ethanol, and NH3. We found that these molecules are all physically adsorbed on the diazine monolayer with weak adsorption strength and charge transfer between the molecules and the monolayer, but the physisorption of only NH3, acetone, and ethanol remarkably modified the electronic properties of the diazine monolayer, especially for the obvious change in electric conductivity, showing that the diazine monolayer is highly sensitive to acetone, NH3, and ethanol. Further, the adsorption of NH3, acetone, and ethanol molecules remarkably modifies, in varying degrees, the optical properties of the diazine monolayer, such as work function, absorption coefficient, and the reflectivity, whereas adsorption of other molecules has infinitesimal influence. The different adsorption behaviors and influences of the electronic and optical properties of molecules on the monolayer show that the diazine monolayer has high selectivity to NH3, acetone, and ethanol. The recovery time of NH3, acetone, and ethanol molecules is, respectively, 1.2 μs, 7.7 μs, and 0.11 ms at 300 K. Thus, the diazine monolayer has a high application potential as a room-temperature acetone, ethanol, and NH3 sensor with high performance (high selectivity and sensitivity, and rapid recovery time).

Heterocycle-derived aldehydes are challenging substrates in metal-catalysed hydroacylation chemistry. We show that by using azine N-oxide substituted aldehydes, good reactivity can be achieved, and that they are highly effective substrates for the intermolecular hydroacylation of alkynes. Employing a Rh(i)-catalyst, we achieve a mild and scalable aldehyde C–H activation, that permits the coupling with unactivated terminal alkynes, in good yields and with high regioselectivities (up to >20 : 1 l:b). Both substrates can tolerate a broad variety of functional groups. The reaction can also be applied to diazine aldehydes that contain a free N-lone pair. We demonstrate conversion of the hydroacylation products to the corresponding azine, through a one-pot hydroacylation/deoxygenation sequence. A one-pot hydroacylation/cyclisation, using N-Boc propargylamine, additionally leads to the synthesis of a bidentate pyrrolyl ligand., Heterocycle-derived aldehydes are challenging substrates in metal-catalysed hydroacylation chemistry; using the N-oxide derivatives allows efficient reactions to be achieved.

Thermally activated delayed fluorescence (TADF) materials have attracted intensive interests in recent decade owing to their intrinsic merits of 100% exciton collection capability and relatively low-cost device fabrication. An abundance of TADF emitters with donor-acceptor structure have been reported. Among them, the diazine-based TADF derivatives can not only form a wide range of emission spanning the entire region from deep blue to near-infrared through rational molecular design, but also realize multiple exciton utilization channels, such as aggregation-induced emission (AIE), room-temperature phosphorescence (RTP) and mechanochromic luminescence (MCL). Such diversiform variability in the same acceptor system is extremely infrequent and deserves in-depth understanding. Herein, a comprehensive review of diazine-based TADF materials is presented according to the relative position of two nitrogen atoms, including pyridazine, pyrimidine and pyrazine derivatives. Their molecular design, optoelectronic behavior, and related application in organic light-emitting diodes (OLEDs) have been systematically summarized, especially focusing on the subtle structure–property relationship. This review provides a guideline and further direction for the development of high-efficient and multifunctional luminescent materials.

© 2020, Akadémiai Kiadó, Budapest, Hungary. New coordination compounds have been synthesized by reacting Zn(II) and Co(II) nitrate or acetate in the presence of triethylamine with Schiff-base ligands containing diazine-ring, pyridine-2-carbaldehyde phthalazine-1-hydrazone, HzPYH, and di(2-pyridyl)ketone 3-chloro-pyridazine-6-hydrazone, HpDPKH. Complexes of [Co(HzPY)2]·3.4H2O, [Zn(HzPY)2] and [Co(HpDPK)2]NO3·H2O were obtained. The crystal and the molecular structure of [Co(HzPY)2]·3.4H2O were determined using X-ray diffraction structure analysis. The compounds were characterized by elemental analysis, FT-IR and UV–Vis spectral data, conductivity and magnetic measurements, too. Except for the diamagnetic Co(III) compound with a nitrate counter-ion, [Co(HpDPK)2]NO3·H2O, all the complexes are neutral-type. The magnetic moment of [Co(HzPY)2]·3.4H2O indicated a low-spin octahedral complex which is relatively rear amongst octahedral Co(II) complexes. Hence, its magnetic moment was measured in the temperature range of 3–300 K. To obtain products in the form of single crystals and/or to increase the yield, the reactions were carried out in solutions with different solvents or recrystallized from solvent mixtures. To determine the nature of the solvent (if any) in the crystalline products and to gain better insight into the decomposition mechanism, coupled TG–MS measurements were carried out. The desolvated compounds were stable at relatively high temperatures (> 200 °C). The cytotoxic, antiproliferative and efflux pump inhibitory effects of the compounds were tested in multidrug-resistant mouse T-lymphoma cells to study their effect on the suppression of MDR. The antibacterial activity of the compounds was also tested. The results of the antibacterial tests were analysed to understand better the effect of the central atoms and the structure on a specific activity.

1H NMR spectroscopy was applied to study the catalytic activity of dinuclear Pd(II)-aqua complexes with different benzodiazine bridging ligands, [{Pd(en)(H2O)}2(μ-qx)]4+ (Pd1), [{Pd(en)(H2O)}2(μ-qz)]4+ (Pd2) and [{Pd(en)(H2O)}2(μ-phtz)]4+ (Pd3) (qx, qz and phtz denote quinoxaline, quinazoline and phthalazine, respectively), in the hydrolytic cleavage of the amide bond in N-acetylated L-methionylglycine (Ac–L–Met–Gly) and L-histidylglycine (Ac–L–His–Gly) dipeptides. All reactions were investigated with an equimolar amount of the reactants at pH = 2.0–2.5 in D2O and at 37 °C. The obtained data for the catalytic activity of Pd1–Pd3 complexes are compared with those previously reported for [{Pt(en)(H2O)}2(μ-L)]4+ (L denotes benzodiazine: qx, qz and phtz), [{Pd(en)(H2O)}2(μ-L)]4+ and [{Pt(en)(H2O)}2(μ-L)]4+ (L denotes diazine: pyrazine and pyridazine) complexes. It was found that catalytic activity of these complexes in peptide cleavage is strongly related to the position of the nitrogen atoms in the benzodiazine or diazine bridging ligand. The investigated dinuclear Pd(II) and Pt(II) complexes show catalytic activity in the selective hydrolysis of the Met–Gly amide bond of Ac–L–Met–Gly dipeptide. Moreover, all the above mentioned Pd(II) complexes were also able to catalyze the regioselective hydrolysis of the His–Gly amide bond of Ac–L–His–Gly dipeptide. However, in the reaction with Ac–L–His–Gly, only Pt(II) aqua complexes containing bridging ligands with two nitrogen atoms in the para-position (quinoxaline and pyrazine) were able to cleave this dipeptide.

The crystal structures of four new chiral [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines are described, namely, ethyl 5′-benzoyl-5′H,7′H-spiro[cyclohexane-1,6′-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3′-carboxylate, C19H22N4O3S, ethyl 5′-(4-methoxybenzoyl)-5′H,7′H-spiro[cyclohexane-1,6′-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3′-carboxylate, C20H24N4O4S, ethyl 6,6-dimethyl-5-(4-methylbenzoyl)-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C17H20N4O3S, and ethyl 5-benzoyl-6-(4-methoxyphenyl)-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C21H20N4O4S. The crystallographic data and cell activities of these four compounds and of the structures of three previously reported similar compounds, namely, ethyl 5′-(4-methylbenzoyl)-5′H,7′H-spiro[cyclopentane-1,6′-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3′-carboxylate, C19H22N4O3S, ethyl 5′-(4-methoxybenzoyl)-5′H,7′H-spiro[cyclopentane-1,6′-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3′-carboxylate, C19H22N4O4S, and ethyl 6-methyl-5-(4-methylbenzoyl)-6-phenyl-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C22H22N4O3S, are contrasted and compared. For both crystallization and an MTT assay, racemic mixtures of the corresponding [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines were used. The main manner of molecular packing in these compounds is the organization of either enantiomeric pairs or dimers. In both cases, the formation of two three-centre hydrogen bonds can be detected resulting from intramolecular N—H...O and intermolecular N—H...O or N—H...N interactions. Molecules of different enantiomeric forms can also form chains through N—H...O hydrogen bonds or form layers between which only weak hydrophobic contacts exist. Unlike other [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines, ethyl 5′-benzoyl-5′H,7′H-spiro[cyclohexane-1,6′-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3′-carboxylate contains molecules of only the (R)-enantiomer; moreover, the N—H group does not participate in any significant intermolecular interactions. Molecular mechanics methods (force field OPLS3e) and the DFT B3LYP/6-31G+(d,p) method show that the compound forming enantiomeric pairsviaweak N—H...N hydrogen bonds is subject to greater distortion of the geometry under the influence of the intermolecular interactions in the crystal. For intramolecular N—H...O and S...O interactions, an analysis of the noncovalent interactions (NCIs) was carried out. The cellular activities of the compounds were tested by evaluating their antiproliferative effect against two normal human cell lines and two cancer cell lines in terms of half-maximum inhibitory concentration (IC50). Some derivatives have been found to be very effective in inhibiting the growth of Hela cells at nanomolar and submicromolar concentrations with minimal cytotoxicity in relation to normal cells.

Guided by computational analysis, herein we report the design, synthesis and evaluation of four novel diazine-based histone deacetylase inhibitors (HDACis). The targets of interest (TOI) are analogues of panobinostat, one of the most potent and versatile HDACi reported. By simply replacing the phenyl core of panobinostat with that of a diazine derivative, docking studies against HDAC2 and HDAC8 revealed that the four analogues exhibit inhibition activities comparable to that of panobinostat. Multistep syntheses afforded the visualized targets TOI1, TOI2, TOI3-rev and TOI4 whose biological evaluation confirmed the strength of HDAC8 inhibition with TOI4 displaying the greatest efficacy at varying concentrations. The results of this study lay the foundation for future design strategies toward more potent HDACis for HDAC8 isozymes and further therapeutic applications for neuroblastoma.

International audience; Diazines are electron deficient six-membered aromatic rings heterocycles which have successfully been employed in the design of a wide range of push-pull chromophores for various applications in the field of organic electronics and optoelectronics. For instance, some have been specifically designed to be inserted in the electroluminescent emission layer of organic light emitting diodes (OLED). OLED technology has continuously evolved and is currently used in industry for display and lighting purposes, offering many advantages including low turn-on voltage and power consumption. In the prospect to further reduce energy waste, a third generation of OLED based on thermally activated delayed fluorescence (TADF), which allows harvesting both triplet and singlet excitons, attracts increasing attention from the scientific community. In this review, we provide a comprehensive overview of the present status of diazine-based dyes developed for TADF. The pyrimidine core is by far the most used and has demonstrated deep blue, blue or sky-blue and green emission when combined with carbazole, acridan and phenoxazine fragments, respectively. Further design of TADF emitters is desirable to afford red OLED and both the pyrazine and pyridazine cores have been scarcely explored.

The increased bioavailability of aluminum has led to a concern about its toxicity on living systems. Among the most important toxic effects, it has been proven that aluminum increases oxidative stress in biological systems, a controversial fact, however, due to its non-redox nature. In the present work, we characterize in detail how aluminum can alter redox equilibriums by analyzing its effects on the thermodynamics of the redox scavenging reaction between DPPH . , a radical compound often used as a reactive oxygen species model, and hydroquinones, a potent natural antioxidant. For the first time, theoretical and experimental redox potentials within aluminum biochemistry are directly compared. Our results fully agree with experimental reduction and oxidation potentials, unequivocally revealing how aluminum alters the spontaneity of the reaction by stabilizing the reduction of DPPH· to DPPH − and promoting a proton transfer to the diazine moiety, leading to the production of a DPPH-H species. The capability of aluminum to modify redox potentials shown here confirms previous experimental findings on the role of aluminum to interfere with free radical scavenging reactions, affecting the natural redox processes of living organisms.

The title compound, a new inhibitor of the Hepatitis B virus (HBV), was prepared via alkyl­ation of 3-(chloro­meth­yl)-5-(pentan-3-yl)-1,2,4-oxa­diazole in anhydrous dioxane in the presence of tri­ethyl­amine., The title compound, C15H22N4O5S, was prepared via alkyl­ation of 3-(chloro­meth­yl)-5-(pentan-3-yl)-1,2,4-oxa­diazole in anhydrous dioxane in the presence of tri­ethyl­amine. The thia­diazine ring has an envelope conformation with the S atom displaced by 0.4883 (6) Å from the mean plane through the other five atoms. The planar 1,2,4-oxa­diazole ring is inclined to the mean plane of the thia­diazine ring by 77.45 (11)°. In the crystal, mol­ecules are linked by C—H⋯N hydrogen bonds, forming chains propagating along the b-axis direction. Hirshfeld surface analysis and two-dimensional fingerprint plots have been used to analyse the inter­molecular contacts present in the crystal. Mol­ecular docking studies were use to evaluate the title compound as a potential system that inter­acts effectively with the capsid of the Hepatitis B virus (HBV), supported by an experimental in vitro HBV replication model.

Encouraged by the developments in the synthesis of novel two-dimensional (2D) materials through bottom-up approaches, we investigate the structural properties and stability of a variety of 2D monolayers constructed from aromatic six-membered rings using density functional theory methods. We study benzene, single heteroatom heterocycles, as well as borazine, 1,3-diazine, and 1,3,5-triazine as building blocks of graphene-like monolayers. Through an analysis of the relative stability of the 2D layers with respect to their molecular constituents, we find that diazine and borazine monolayers present the greatest stability of all studied compounds. These large bandgap holey materials open the possibility of a whole family of 2D sheets based on seamlessly connected six-membered rings that can show promise in applications such as catalysis and gas separation.

Heterocyclic 1,3-diazine nucleus is a valuable pharmacophore in the field of medicinal chemistry and exhibit a wide spectrum of biological activities. PharmMapper, a robust online tool used for establishing the target proteins based on reverse pharmacophore mapping. PharmMapper study is carried out to explore the pharmacological activity of 1,3-diazine derivatives using reverse docking program. PharmMapper, an open web server was used to recognize for all the feasible target proteins for the developed compounds through reverse pharmacophore mapping. The results were analyzed via molecular docking with maestro v11.5 (Schrodinger 2018-1) using GTPase HRas as possible target. The molecular docking studies displayed the binding behavior of 1,3-diazine within GTP binding pocket. From the docking study compounds s3 and s14 showed better docked score with anticancer potency against cancer cell line (HCT116). Hence, the GTPase HRas may be the possible target of 1,3-diazine derivatives for their anticancer activity where the retrieved information may be quite useful for developing rational drug designing. Furthermore the selected 1,3-diazine compounds were evaluated for their in vitro anticancer activity against murine macrophages cell line. 1,3-Diazine compounds exhibited good selectivity of the compounds towards the human colorectal carcinoma cell line instead of the murine macrophages. The toxicity study of the most active compounds was also performed on non cancerous HEK-293 cell line. Electronic supplementary material The online version of this article (10.1186/s13065-019-0613-8) contains supplementary material, which is available to authorized users.

The pyrimidinyl hydrazone ligand O C{NHN C(Me)(pm)}2 (pm = 2-pyrimidinyl) (L3H2) has two potentially protic H atoms and multiple donor atoms. The reaction of L3H2 with CuCl2·2H2O yielded the tetranuclear complex [Cu4(L3H)2Cl6(CH3OH)2] (1). Structural studies on 1 reveal the molecule is located about a crystallographic inversion centre, affording two crystallographically independent Cu(II) centres with the two symmetry equivalent [Cu2(L3H)Cl3CH3OH] units connected via µ2-Cl bridges to generate a linear tetranuclear copper complex. The ligand is singly deprotonated (L3H−) and twisted around the diazine N N′ bond, affording an N3 donor set for the Cu1 centre and an N2O donor set for the Cu2 centre. The Cu1 ion is five coordinate with an [N3] donor set from the L3H− ligand and the remaining two sites occupied by Cl− anions. The Cu2 ion is six coordinate with the L3H− ligand offering a mer [N2O] donor set, with the three remaining sites occupied by two Cl− anions and a MeOH molecule. Magnetic studies reveal the presence of strong antiferromagnetic interactions via the diazine bridge linking the Cu1 and Cu2 ions and moderate ferromagnetic interactions via the chloro bridges located about the inversion centre, connecting the Cu2 and Cu2i ions.

Two different luminescent rhenium complexes, having the general formula [Re2(μ-Cl)2(CO)6(μ-1,2-diazine)] and containing two different diazine ligands, namely 4-(pyridazin-4-yl)-butanoic acid (Re-1) and 8-(5-methylpyridazin-4-yl)-octanoic acid (Re-2), were prepared. Exploiting the presence of the carboxylic acid moieties, both complexes were further covalently linked to a 20-mer oligomer (PNA1), bearing a nucleobase sequence complementary to that of mature miR-21–5p (5′-TCAACATCAGTCTGATAAGCTA-3′), as well as to a 20-mer oligomer (PNA2) used as a negative control bearing the sequence 5′-GTGTAACACGTCCTATACGCC-3’. The resulting four Re-PNA conjugates were characterized and used to target miR-21 in the DU145 prostate cancer cell line. The conjugation with PNA did not perturb the photoluminescence behavior of the organometallic fragments: emission from 3MLCT excited states, centered in a range between 580 and 610 nm, was observed, with satisfactory photoluminescence quantum yields (Φ = ca. 0.03–0.01, in aerated water/acetonitrile solution 1/1). Experiments of cell uptake, performed with living prostate cancer cells showed that the length of the aliphatic linker between the rhenium complex and the PNA sequence, strongly affects the cellular localization.

Excitation of the valence electronic states of the pyridazine molecules in the gas phase have been studied using the technique of electron energy-loss spectroscopy. Varying the electron scattering conditions, the residual electron energy and scattering angle, enabled the optically-allowed and -forbidden excitations to be differentiated. The measured energy-loss spectra enabled the vertical excitation energies of the observed states to be determined and tentative assignments for them to be obtained. Comparison of the available vertical excitation energies of the correlating triplet and singlet states of the diazine molecules, pyridazine, pyrimidine and pyrazine, allowed systematic trends in the energy shifts to be determined.

This article describes the synthesis of 2-(2-oxo-2-arylethylidene)-2,3-dihydropyrimidin-4(1Н)-ones and provides details of their reactivity, such as nucleophilic and electrophilic substitution, as well as associated processes: acidic degradation, isomerization, and diazine ring cleavage.

g-C3N4 is a visible-light photocatalyst with a suitable band gap and good stability. Moreover, g-C3N4 is considered to be earth-abundant, which makes it an appealing photocatalyst. However, due to its small specific surface area, low utilization of visible light, and high photogenerated electron-hole pair recombination rate, the photocatalytic activity of g-C3N4 remains unsatisfactory. In this work, a highly efficient nonmetallic photocatalyst, i.e., g-C3N4 doped with uracil (denoted U-C3N4) was successfully developed. Based on the various characterizations and calculations, it is shown that the triazine group in g-C3N4 is replaced with the diazine group in uracil. This occurrence leads to the formation of a new electron-transfer pathway between triazine groups, which can promote the separation of photogenerated electrons and holes. Concurrently, due to the ultrathin structure of the as-prepared U-C3N4, the material possessed a larger specific surface area than pristine g-C3N4, which can provide more active sites. Furthermore, the transfer pathway between the electron and hole was also shortened, and the recombination of the electron and hole was inhibited. According to the results, an optimal hydrogen evolution rate of 31.7 mol h-1 g-1 was achieved by U-C3N4, which is 5.1 times higher as compared to that achieved by pristine g-C3N4 (6.26 mol h-1 g-1). For the photocatalytic degradation of rhodamine B, the reaction rate constant of U-C3N4 (11.3 × 10-2 min-1) is about 5.5 times that of g-C3N4 (2.07 × 10-2 min-1). Furthermore, the uracil-doped catalyst was also able to demonstrate good stability after five successive runs.

The development of microorganisms on the surface of building materials, in pores or cracks, leads to the destruction or dissolution of this material. One of the most common and effective ways to protect building materials and structures from microbiologically influenced corrosion (MIC) is the use of biocidal drugs. The biocidal activity of a number of fluorinated derivatives of 1,3-diazines and 1,2,4-triazoles against Bacillus mucilaginosus cells has been studied. This bacterium is an active destroyer of silicates and aluminosilicates. The mineral-destroying role of this microorganism is associated with the synthesis of exopolysaccharides and acidic low-molecular-weight metabolites. It was found that in a series of 6-fluorinated of 2-amino- (I), 2-hydroxy- (II), 2-mercapto- (III) and 2-methylthio- (IV) pyrimidines, 2-methylthio- (IV) derivatives have the greatest biocidal effect, the suppression zones vary from 25 mm to 35.5 mm at the studied concentrations (0.6, 6 and 60% (vol.)). Samples of fluorinated of 5-mercapto-1,2,4-triazoles (V) also showed a good protective effect: the zone of growth inhibition of Bacillus mucilaginosus are in the interval from 20.5 mm to 27.5 mm. The greatest biocidal effect is inherent in perfluoroalkyl substituents of the following structure: C6F13 (a), CF(CF3)OC3F7 (c); CF(CF3)OCF2CF(CF3)OC3F7 (d); CF(CF3)[OCF2CF(CF3)]2OC3F7 (e). Their use as a protective coating, especially concrete, will ensure a longer safe operation.

The preferred site of alkylation of diazine N-oxides by representative hard and soft alkylating agents was established conclusively using the 1H–15N HMBC NMR technique in combination with other NMR spectroscopic methods. Alkylation of pyrazine N-oxides (1 and 2) occurs preferentially on nitrogen regardless of the alkylating agent employed, while O-methylation of pyrimidine N-oxide (3) is favoured in its reaction with MeOTf. As these outcomes cannot be explained in the context of the hard/soft acid/base (HSAB) principle, we have instead turned to Marcus theory to rationalise these results. Marcus intrinsic barriers (ΔG‡0) and ΔrG° values were calculated at the DLPNO-CCSD(T)/def2-TZVPPD/SMD//M06-2X-D3/6-311+G(d,p)/SMD level of theory for methylation reactions of 1 and 3 by MeI and MeOTf, and used to derive Gibbs energies of activation (ΔG‡) for the processes of N- and O-methylation, respectively. These values, as well as those derived directly from the DFT calculations, closely reproduce the observed experimental N- vs. O-alkylation selectivities for methylation reactions of 1 and 3, indicating that Marcus theory can be used in a semi-quantitative manner to understand how the activation barriers for these reactions are constructed. It was found that N-alkylation of 1 is favoured due to the dominant contribution of ΔrG° to the activation barrier in this case, while O-alkylation of 3 is favoured due to the dominant contribution of the intrinsic barrier (ΔG‡0) for this process. These results are of profound significance in understanding the outcomes of reactions of ambident reactants in general.

Using LiCl as a chlorine source, the chlorination of 2-aminopyridines or 2-aminodiazines in the presence of Selectfluor and DMF is established under mild conditions. This method gives chlorinated pyridines or diazines in good to high yields with high regioselectivities. Also, this method is extended to the bromination of 2-aminopyridines or 2-aminodiazines by using LiBr. The regioselectivity of the chlorination reaction is strongly dependent upon the substituent pattern in either the 2-aminopyridines or 2-aminodiazines. The synthesis of Buparlisib from chlorinated pyridines was explored. A study of the mechanism revealed that this chlorination occurs via either a pyridine or diazine radical process.

A dendrimer based on diazine supported heterogeneous Cobalt nanoparticles (NPs) were synthesized by a reduction method whereas the dendrimer was produced between the reaction of 2,4,6-triamino-1,3-diazine and benzoyl chloride at 80 °C for 8 h. The SEM image of the dendrimer supported Co NPs displayed the globular and agglomerate spherical size and EDX assessment noted the existence of necessary cobalt ion while TG and DSC showed excellent thermal stability. XRD revealed that FCC configuration of Co NPs. By using the Debye–Scherrer formula, the average size of these Co NPs was calculated to 18.10 nm likewise it was found 7.00 nm by the TEM analysis. The dendrimer was also evaluated by IR, 1HNMR, 13CNMR, Mass spectrophotometry, and elemental analysis. The catalytic effect of these nanoparticles catalyst has been studied for Heck coupling reactions in tetrabutylammonium bromide solution and observed excellent catalytic efficiency within very short reaction time (45 min) and also reusable.

The iron(II) complexes of two structural isomers of 2-(1 H-imidazol-2-yl)diazine reveal how ligand design can be a successful strategy to control the electronic and magnetic properties of complexes by fine-tuning their ligand field. The two isomers only differ in the position of a single diazinic nitrogen atom, having either a pyrazine (Z) or a pyrimidine (M) moiety. However, [Fe(M)3](ClO4)2 is a spin-crossover complex with a spin transition at 241 K, whereas [Fe(Z)3](ClO4)2 has a stable magnetic behavior between 2 and 300 K. This is corroborated by temperature-dependent Mossbauer spectra showing the presence of a quintet and a singlet state in equilibrium. The temperature-dependent single-crystal X-ray diffraction results relate the spin-crossover observed in [Fe(M)3](ClO4)2 to changes in the bond distances and angles of the coordination sphere of iron(II), hinting at a stronger σ donation of ligand Z in comparison to ligand M. The UV/vis spectra of both complexes are solved by means of the multiconfigurational wave-function-based method CASPT2 and confirm their different spin multiplicities at room temperature, as observed in the Mossbauer spectra. Calculations show larger stabilization of the singlet state in [Fe(Z)3]2+ than in [Fe(M)3]2+, stemming from the slightly stronger ligand field of the former (506 cm-1 in the singlet). This relatively weak effect is indeed capable of changing the spin multiplicity of the complexes and causes the appearance of the spin transition in the M complex.

Photolysis of the diazine heterocycle, pyrazine, following irradiation at 308, 248, and 193 nm was examined using nanosecond time-resolved Fourier transform infrared emission spectroscopy. The resulting time-resolved IR emission spectra reveal that for 308 and 248 nm vibrationally highly excited pyrazine is produced, but no photolysis products were detected. However, at 193 nm excitation, the measured IR emission spectra consist solely of resonances originating from rovibrationally excited photofragments, including acetylene (HCCH), hydrogen cyanide (HCN), and hydrogen isocyanide (HNC), indicating that photofragmentation proceeds from vibrationally highly excited pyrazine on the ground electronic state. Spectral fit analysis of the time-resolved HCN and HNC IR emission band shapes and intensities allowed an estimate of the nascent product population distributions, from which a lower bound estimate of the HNC/HCN branching ratio was deduced as Φ ≥ 0.07. Additionally, ab initio calculations were performed in order to examine the propensity of photoinduced reactions on the ground- and lowest-energy excited-state surfaces. The calculations provide a basis for understanding the wavelength dependence of the UV photolysis of pyrazine, the photolytic production of HNC, and also explain previous experimental observations in the literature.

The halogenation of pyridinium N -(benzoazynyl) aminides with N -halosuccinimides provides a mild and regioselective method to functionalize the negatively charged diazine moiety in most cases. In some examples, however, formation of other products is explained. Finally, alkylation of the exocyclic nitrogen and reduction of the N–N bond provides a simple and straightforward strategy to obtain functionalized N -benzyl-benzoazynyl-α-amines.

In this work, we performed plasma treatment of thin layers of graphene oxide samples in various nitrogen containing gases (mainly NH3 and N2). Experiments were performed in the preparation chamber of the X-ray photoelectron spectrometer, allowing “in situ” characterization of the treated surface. Introduction of nitrogen into the top surface was intensified by applying negative voltage on the sample between 0 and 300 V accelerating the positive plasma ions towards the sample. Significant amount of nitrogen (≈10 atomic %) was built into the top atomic layers of the graphene oxide samples at application of the 2 types of plasma gases for 10-minute reaction time. When comparing the NH3 and N2 plasma treatments, more complete reduction and closely similar amount of nitrogen was found at applying NH3 plasma. When increasing the bias, the N-content increased, together with decrease of the O content. The high-resolution C1s, O1s, and N1s spectra are broad, representing different chemical states. The peak envelopes of the O1s and N1s lines could be decomposed essentially to 3, while the C1s spectrum to 5 different, well-separated peaks, being identical for all samples. The component peaks were assigned to specific chemical bonding states (N1s: 398.3 eV sp2 pyridine N, 399.7 eV sp2 pyrrole, diazine or triazine N, 401.0 eV N in graphite plane; O1s: 530.8 eV carbonyl, 532.2 eV ether, epoxy, alcohol, ester C═O, 533.6 eV ester C―O―C, carboxyl OH). The relative amounts of C―O and C―N bonding states changed significantly with advancement of the treatment performed at increasing biases.

We report an air-stable bisboron complex as an efficient catalyst for the inverse electron-demand Diels–Alder (IEDDA) reaction of 1,2-diazine as well as 1,2,4,5-tetrazine. Its stability towards air and moisture was demonstrated by NMR studies enabling its application in organic transformations without glovebox. A one-pot procedure for its synthesis was developed starting from 1,2-bis(trimethylsilyl)benzene greatly enhancing its practicality. Comparative reactions were carried out to evaluate its catalytic activity in IEDDA reactions of diazine including phthalazine as well as 1,2,4,5-tetrazine.

Push-pull types Donor-Bridge-Acceptor (D-B-A) organic molecules have been reported as efficient functional materials for various technological applications. Often their interesting properties were reported to be directly linked to their nature of intramolecular charge transfers (ICT). Bridge that connects the D with A, plays the vital role in the ICT processes. A recent report of comparative experimental and computational nonlinear optical (NLO) study, shows many interesting behaviours exhibited by aromatic (diazine, thiophene and benzene rings) bridges. Many earlier studies also exist, where effects of one or more of aromatic bridges were investigated for NLO applications. But no systematic comparative study with well-known aromatic bridges at one place exist in literature. Inspired by those earlier works, this computational work reports the influences of a set of mono-aromatic ring bridges on NLO properties for a set of D-B-A types of organic molecules. This work can be expected to serve as a reference for many researchers working in the search of new and efficient functional materials.

The interaction between KrOF2 or XeOF2 and the 1,2, 1,3, and 1,4 diazines is characterized chiefly by a Kr/Xe⋯N aerogen bond, as deduced from ab initio calculations. The most stable dimers take advantage of the σ-hole on the aerogen atom, wherein the two molecules lie in the same plane. The interaction is quite strong, as much as 18 kcal mol−1. A second class of dimer geometry utilizes the π-hole above the aerogen atom in an approximate perpendicular arrangement of the two monomers; these structures are not as strongly bound: 6–8 kcal mol−1. Both sorts of dimers contain auxiliary CH⋯F H-bonds which contribute to their stability, but even with their removal, the aerogen bond energy remains as high as 14 kcal mol−1. The nature and strength of each specific interaction is confirmed and quantified by AIM, NCI, NBO, and electron density shift patterns. There is not a great deal of sensitivity to the identity of either the aerogen atom or the position of the two N atoms in the diazine.