An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Fragments of 1,2,4-triazolo[5,1-c][1,2,4]triazin-7-one are found in many compounds with various types of biological activities, including the antiviral drug Riamilovir (Triazavirin®), which shows activity against SARS-CoV-2 (COVID-19). Therefore, the development of convenient methods for the synthesis of new derivatives of 1,2,4-triazolo[5,1-c][1,2,4]triazin-7-one is always in demand. This review systematizes the information on the most common synthetic methods for constructing the 1,2,4-triazolo[5,1-c][1,2,4]triazin-7-one heterocyclic system.

An efficient synthetic approach to 3-(4-carboxyphenyl)pyridine-2,6-dicarboxylic acid has been developed on the basis of “1,2,4-triazine” methodology. The title compound is of practical interest, in particular for the preparation of metal–organic frameworks (MOF). No synthesis of this compound has been reported previously.

An efficient procedure has been developed for the synthesis of 2-phenyl-1,3,4-oxadiazole deriva­tives with one or two pyrrolidin-1-yl substituents in the benzene ring via nucleophilic substitution of fluorine in 2-[(di)fluorophenyl]-1,3,4-oxadiazole on heating with pyrrolidine under solvent-free conditions.

An operationally facile and high yielding one-pot protocol has been developed for the preparation of pyridines appended with pyrazole via NH linker. This protocol includes S-N(ipso)/aza-Diels-Alder reactions in up to 54 % yields starting from 1,2,4-triazine precursors. All the synthesized compounds have been evaluated for their in silico activity against JAK1, SYK, and FAK1 kinases. The most promising compound was tested in vitro using A-172, Hs578T, and HepG2 cancer cell lines and exhibited considerable cytotoxicity with IC50 values <50 mu M in A-172 and HepG2 cell lines. Anticancer in vitro activity correlates well with the predicted in silico data.

N-([2,2′-Bipyridin]-6-ylmethylene)cyclohexanamine was prepared by the reaction between cyclohexylamine and 2,2′-bipyridine-6-carbaldehyde. High “turn-on” fluorescence response toward Zn2+ in solutions was observed.

4-(4-Aminophenyl)-2-azinylquinazolines bearing pyridyl or quinolinyl residue in the position 2 have been designed and synthesized. The basic photophysical properties of obtained compounds and their 2-phenylquinazoline counterpart have been investigated in both solution and the solid state. Quinazoline chromophores exhibited positive emission solvatochromism, and the collected data were analyzed using the Lippert-Mataga equation, as well as Kosower and Dimroth/Reichardt scales. Moreover, halochromic properties upon addition of trifluoroacetic acid have been examined; it was shown that chromophores display bathochromically shifted emission band in acidic media due to the protonation at 2-azynylquinazoline fragment. The luminescence response towards metal cations has also been analyzed for the synthesized heterocycles. The obtained data represent an important step for further structure modification to improve sensitivity and selectivity to analyts.

The structures of six 2,2′-bipyridine derivatives containing aromatic amine moieties, namely N-aryl-4-aryl-1-(pyridin-2-yl)-6,7-dihydro-5H-cyclopenta[c]pyridine-3-amines, were studied by single-crystal X-ray diffraction. The molecular structures and the effect of the substituents of these compounds on the crystal packing are discussed.

A series of new 5-aryl-2,2'-bipyridines and their (polyfluoro)salicylate complexes of Cu(II), Co(II) and Mn(II) were synthesized. Their antimicrobial activity was evaluated in vitro against six strains of Trichophytons, E. floccosum, M. canis, C. ablicans and Gram-negative bacteria N. gonorrhoeae. Among azo-ligands, Ph-bipy and Tol-bipy showed promising antifungal activity (minimum inhibitory concentration (MIC)<0.8-27 mu M). Their antifungal action was found can be realized via binding Fe(III) ions. Tol-bipy suppressed growth of Gram-positive bacteria S. aureus, S. aureus MRSA and their monospecies biofilms (MIC 6-16 mu M). Using molecular docking, the anti-staphylococcal action mechanism based on the inhibition of S. aureus DNA gyrase GyrB was proposed for the lead compounds. Among metal complexes, Cu(II) and Mn(II) complexes based on tetrafluorosalicylic acid and Tol-bipy or Ph-bipy had the high antifungal activity (MIC<0.24-32 mu M). Mn(SalF(4)-2H)(2)(Tol-bipy)(2)] suppressed the growth of seven Candida strains at MIC 12-24 mu M. [Cu(Sal-2H)(Ph-bipy)] and [Cu(SalF(3)-2H)(Ph-bipy)(2)] showed the promising anti-gonorrhoeae activity (MIC 4.2-5.2 mu M). (Cu(SalF(n)-2H)(Tol-bipy)(2)], [Cu-(SalF(4)-2H)(Ph-bipy)(2)] and [Cu(SalF(3)-2H)(Ph-bipy)(2)]) were found active against the bacteria of S. aureus, S. aureus MRSA and their biofilms (MIC 2.4-41.4 mu M). The most active compounds were tested for toxicity in vitro against human embryonic kidney (HEK-293) cells and in vivo experiments with CD-1 mice.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Two series of V-shaped 6,7-dihydro-5H-cyclopenta[c]pyridine chromophores bearing two 5-arylthiophen-2-yl fragments as well as pyridyl or quinolinyl residue have been designed and synthesized. The basic photo-physical properties of the compounds have been investigated both in solutions and the solid state. 3,4-Bis(5-(4-diethylaminophenyl)thiophen-2-yl)-1-(quinolin-2-yl)-6,7-dihydro-5H-cyclopenta[c]pyridine 2a demonstrated positive emission solvatochromism, and the collected data were analyzed by using Lippert-Mataga equation, as well as Kosower and Dimroth/Reichardt scales. The ability to detect metal cations has been analyzed for the obtained heterocycles. It is found that addition of 1.5 eq of Cu2+ to diphenylamino-substituted chromophore 1b lead to totally luminescence quenching and solution of chromophore 1b turns dark yellow that can be seen with the naked eye. Additionally, halochromic properties have been examined, it was shown that diethylamino de-rivatives 1a and 2a demonstrated blue shifts in both absorption and emission spectra upon the treatment with TFA. Also, we checked emission behavior of chromophore 1a in MeCN-water mixtures with different water volume fractions. Finally, DFT calculations have been performed and according data, the replacement of pyridyl residue with quinolinyl one in studied heterocyclic ensembles leads to decrease in the value of energetic gap.

Various conditions for the inverse electron-demand aza-Diels–Alder reaction in the series of 5-aryl-3-(2-pyridyl)-1,2,4-triazine-5-carbonitriles and 2-amino-4-aryloxazoles to obtain 4,5-diaryl-3-hydroxy-2,2'-bipyridine-6-carbonitriles were tested. Heating in 1,2-dichlorobenzene or under solvent-free conditions were found to be the most effective.

3-Hydroxy-4-(4-methoxyphenyl)-5-phenyl-2,2'-bipyridine-6-carbonitrile was synthesized by the aza-Diels–Alder reaction between 4-(4-methoxyphenyl)oxazole-2-amine and 6-phenyl-3-(2-pyridyl)-1,2,4-triazine-5-carbonitrile. The 3-methoxy derivative of the product was synthesized by the O-methylation reaction. The photophysical characteristics of both compounds were studied. The alkylation of the 3-hydroxy group at the position of C3 of 2,2'-bipyridine leads to a significant increase in the photoluminescence intensity.

The present study describes a facile and solvent free synthesis of 1,2,4-triazine antipyrine derivatives (2a–f) in prominent yields (70–85%) over nucleophilic substitution of 5-carbonitrile triazines. Further, we strained to convert them into pyridine analogues (3a–f) over aza-Diels-Alder reaction with norbornadiene as dienophile but it was an unsuccessful attempt. It is an assumption we made that the antipyrine substituent primes the triazine electronically unfavorable at 1,2-aza position. All the synthesized compounds were confirmed by using 1H NMR, 19F NMR, 13C NMR and Mass spectral studies. Furthermore, this stated synthetic approach is ecofriendly as there are no toxic intermediates and also, the antipyrine derivatives can be aiding as promising templates for the development of new pharmaceutical scaffolds.

A new co-polymer based on fragments of 2-(2-pyridyl)monoazatriphenylene and 2,5-bis (2-ethylhexyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione was prepared by using the Sonogashira reaction. The photophysical properties of the polymer were studied. The presence of a strong bathochromic shift of the absorption and emission maxima in comparison with the previously described monomer units is shown. The polymer exhibits an intense “turn-off” response toward Cu2+ cations.

Показана возможность получения 1,2,4-триазинов, имеющих в положении С5 остаток 3-амино-5-метоксикарбонилтиофена, в результате нуклеофильного ипсо -замещения цианогруппы в отсутствие растворителя.

A series of coumarin-pyridine-based push-pull fluorophores were prepared starting from 1,2,4-triazines by using direct C-H functionalization (S-N(H)-reaction)-Diels-Alder-retro Diels-Alder domino reaction sequence. This efficient synthetic strategy allowed to obtain a series of 19 coumarin-pyridine fluorophores. Their photophysical properties were studied. While pyridine-substituted derivatives of 4-alkylcoumarins may be considered as alternative to coumarin dyes characterized by emission maxima mainly in a visible region with wavelengths of 402-415 nm, absorption in the UV range at 210-307 nm, and good photoluminescence quantum yields of 6-19%, all the derivatives of 4-phenylcoumarin did not exhibit any noticeable fluorescence. More detailed photophysical studies were carried out for two the most representative derivatives of 4-alkyl-coumarin-pyridines to demonstrate their positive solvatochromism, and the collected data were analyzed by using Lippert-Mataga equation, as well as Kosower and Dimroth/Reichardt scales. The obtained results demonstrate that the combining two chromophore systems, such as 2,5-diarylpyridine and coumarin ones, is promising in terms of improving the photophysical properties of the new coumarin-pyridine hybrid compounds. (C) 2021 Elsevier B.V. All rights reserved.