This paper explores a synthetic pathway for naphtopyrazolotriazines utilizing amines as versatile starting materials. The approach leverages the reactivity of amines to construct the triazine core, fused with naphtho and pyrazolo cycles, through a series of controlled diazo coupling and cyclization reactions. By employing amines, this method allows for the introduction of varied substituents, enabling the tailoring of electronic and steric properties to suit specific potential applications. The significance of this work lies in its efficiency, scalability, and potential to synthesize compounds with tunable functionalities. Naphtopyrazolotriazines are of interest due to the presence of a pyrazolo triazine moiety, which is known for its bioactivity, including anticancer and antimicrobial properties, and their possible utility in optoelectronic materials. All synthesized compounds have been characterized by 1D and 2D NMR, IR, UV-Vis, and mass spectrometry. Additionally, UV-Vis and fluorescence spectra of the synthesized compounds, together with the frontier molecular orbitals energies, were calculated by DFT methods implemented in Gaussian 09W software.

Background: 8-Quinolinol and its derivatives are drawing significant attention across various disciplines due to their remarkable versatility. These compounds are well-known for their exceptional chelating ability, forming stable metal complexes via their nitrogen and oxygen electron donor atoms. This main characteristic determines their broad utility. Biological activity can also be explained by the chelating capacity, which allows 8-quinolinol to bind to essential metal ions such as Fe, Zn, Cu, and others. This chelation disrupts metal-dependent biological processes in target cells or organisms, leading to a range of effects, including antimicrobial, anticancer, antifungal, and neuroprotective activities. On the other hand, the biological activity of pyrazole derivatives is attributed to their heterocyclic structure, which allows for interactions with biological targets that can lead to enzyme inhibition, receptor antagonism, radical scavenging, and other effects. Objective: This work aimed to synthesize and characterize novel diazene compounds derived from 8-quinolinol or 2-methyl-8-quinolinol and pyrazole amines, and to evaluate their antimicrobial and anticancer activities. Methods: The compounds have been synthesized by coupling diazonium salts obtained from the diazotization of heterocyclic amines with 8-quinolinol and its derivative, 2-methyl-8-quinolinol. The careful selection of reaction conditions enabled the synthesis of high-purity products. The compounds were characterized by 1D and 2D NMR, FT-IR spectroscopy, UV-Vis spectroscopy, and LC-HRMS analysis. The biological activity of the newly synthesized compounds was evaluated following the protocols of EU-OPENSCREEN, a European Research Infrastructure Consortium (ERIC) initiative dedicated to supporting early drug discovery. Results: By combining diazonium salts obtained from 3-methyl-1H-pyrazol-5-amine and ethyl 5-amino-3-methyl-1H-pyrazole-4-carboxylate with the aforementioned coupling agents, four novel 8-quinolinol derivatives were synthesized. The further hydrolysis of the ethoxy carbonyl functional group allowed its conversion to a carboxylic functional group, thus expanding the series of new compounds to six members. Several compounds from the series have proven to be biologically active against several human pathogenic microorganisms and the Hep-G2 cancer cell line. Conclusions: The combination of two well-known biologically active scaffolds through a classic diazo coupling reaction allowed the synthesis of novel biologically active compounds, which showed promising results as possible antifungal and anticancer agents. These results represent a foundation for future studies, which will include a broader biological screening and in vivo studies.

Nitrogen-containing heterocycles are essential compounds in nature, and their structural and functional diversity inspired the synthesis of a wide range of derivatives with diverse applications as pharmaceuticals, agrochemicals, dyes, polymers, cosmetics, etc. Among them, N-fused heterocycles represent an important category, due to their high potential as biologically active agents. Pyrazolo[5,1-c][1,2,4]triazoles, a class of nitrogen heterobicycles, have multiple applications as dyes and pigments. Also, a number of compounds containing this structure have been investigated for their biological activities. All the main experimental results published in the literature (both articles and patents) regarding the latter are summarized in this review.

The nitrosation of 1H-1-alkyl-6-methyl-3-phenylpyrazolo[5,1-c][1,2,4]triazoles leads to new 1H-1-alkyl-6-methyl-7-nitroso-3-phenylpyrazolo[5,1-c][1,2,4] triazoles that react in acidic media, giving rise to 1H-1-alkyl-7-hydroxyimino-6-methyl-3-phenylpyrazolo[5,1-c][1,2,4]triazolium salts. These compounds were characterized by FT-IR, UV-Vis, 1H-NMR, 13C-NMR, and 15N-NMR spectroscopic techniques.

In this paper, we present the synthesis, characterization and evaluation of antiproliferative activity for four compounds carrying the 4-amino-5-mercapto-1,2,4-triazol-3-yl scaffold. The synthesis of 1,n-bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl) alkanes was carried out using as starting reagents the dihydrazides of oxalic, malonic, succinic and adipic acids, using mercaptoacetic acid dianion as a leaving group, by a one-pot synthesis method implemented in our research group for the synthesis of 3-substituted-5-mercapto-1,2,4-triazoles. The compounds were obtained with modest yields (12–60%) but with good purity and were characterized by elemental analysis, FTIR, 1H-NMR and 13C-NMR spectroscopy. Also, the stability of the synthesized bis-triazoles was investigated under controlled thermal stress in a dynamic oxidative atmosphere. The last part of the study consisted of biological activity evaluation, by evaluating the antiproliferative activity against the A375 line (human malignant melanoma), as well as on viability of the BJ fibroblast cell line, using MTT and LDH assays.

When 1-benzoylthiosemicarbazide (2) or thiosemicarbazide (1) were treated with benzoyl chloride in a basic medium, a mixture of two compounds was obtained: 1,2-dibenzoylthiosemicarbazide (3) and 1,4-dibenzoylthiosemicarbazide (4). To determine the structure of the novel compounds, 2D NMR spectroscopy techniques such as 1H-13C and 1H-15N were employed.

A novel approach for the enzymatic esterification of carbohydrate polyols with fatty acids was investigated, with reactive natural deep eutectic solvents (R-NADES) as reaction medium and source of reagents. Three binary hydrophilic R-NADES consisting of choline chloride (ChCl) as hydrogen bond acceptor (HBA) and sugar alcohols (D-sorbitol, xylitol, D-arabitol) as hydrogen bond donors (HBD), were prepared and characterized. The carbohydrate polyol-based R-NADES were durable viscous fluids between 40 and 800C, the common temperature range for an enzymatic reaction. The commercially accessible lipase B from Candida antarctica immobilized on acrylic resins (LAR) showed significant esterification activity and exceptional thermal stability in all three tested R-NADES and successfully catalyzed the synthesis of polyol esters. Box Behnken factorial design with three levels-three variables was used for optimizing the reaction conditions. The preparative esterification of D-arabitol with lauric acid (LA) at predicted optimal values for enzyme load, (i.e., 800 U/gram D-arabitol), temperature (70 degrees C) and LA/D-arabitol molar ratio of 1), attained 80 mol% LA conversion after 24 h reaction time. Structural analysis based on mass, infrared and nuclear magnetic resonance spectroscopy demonstrated that the reaction product is solely the diester 1,5-dilauryl-D-arabitol (1,5-DLDA). The 1,5-DLDA product, with an NMR-purity above 99.9%, was isolated in 95% yield. Under similar conditions, 1,5-dilauryl-xylitol (1,5-DLX) and 1,6dilauryl-D-sorbitol (1,6-DLDS) were obtained, at a LA conversion of 56 mol% and 62 mol%, respectively. A combination of docking and molecular dynamics simulations allowed to rationalize the structural stability of the lipase B from Candida antarctica (CalB) active site in R-NADES, as well as the selectivity of the catalyzed esterification.

The present paper describes the preparation and characterization of a new dinuclear ligand based on terpyridine featuring a diselenide unit. This new compound was synthesized in a two-step procedure that first involved the insertion of the diselenide moiety on a carboxylic acid and was followed by a Steglich esterification reaction between the biscarboxylic acid containing the diselenide unit and 2,6-di(pyridin-2-yl)pyridin-4-ol (tpyOH). The title compound was characterized via FT-IR, Raman, NMR (1D and 2D), and UV-Vis spectroscopies and elemental analysis. Emission properties were investigated.

A new azo compound was synthesized via an azo coupling reaction between 4-(phenyldiazenyl)benzenediazonium chloride and 8-hydroxyquinoline (8-Hq). The new diazene compound can be used to synthesize metal complexes as a derivative of 8-Hq. The structure of the new compound was characterized using UV–Vis, FT-IR, and 2D NMR spectroscopic methods.

A new triazol-3-one resulted unexpectedly from the reduction reaction of a heterocyclic thioketone using sodium borohydride in pyridine containing a small amount of water. The structure of the new compound was characterised using FT-IR, 1D and 2D NMR, and HRMS spectroscopic methods.

The scope of the current work was to synthesize an S-alkylated 1,2,4-triazole-3-thiol derivative. Synthesis was carried out in two steps: in the first step, 4,5-diphenyl-4H-1,2,4-triazole-3-thiol was S-alkylated using a halogenated acetal and cesium carbonate. In the second step, several acetal deprotection procedures were tested, and the aldehyde obtained was isolated as a bisulfite adduct. The structures of the new compounds were characterized by FT-IR, 1D, and 2D NMR spectroscopic methods.

Pyrazolo[5,1-c][1,2,4]triazoles are bicyclic nitrogen heterocyclic compounds belonging to the azoloazole class, containing one bridgehead nitrogen atom. They are particularly useful dye and pigment products, with applications in a wide variety of fields. They have also been investigated as biologically active compounds with potential applications in medicine and agriculture. Many methods for the preparation of pyrazolo[5,1-c][1,2,4]triazoles have been researched, due to different needs in terms of structure, functionalization etc.; several of them are currently applied on an industrial scale. This review comprehensively describes and discusses the synthetic methods for the preparation of pyrazolo[5,1-c][1,2,4]triazoles published in the literature from the beginning (ca. 1970) until 2020.

Pyrazolo[5,1-c][1,2,4]triazoles are bicyclic nitrogen heterocyclic compounds belonging to the azoloazole class, containing one bridgehead nitrogen atom. They are particularly useful dye and pigment products, with applications in a wide variety of fields. They have also been investigated as biologically active compounds with potential applications in medicine and agriculture. Many methods for the preparation of pyrazolo[5,1-c][1,2,4]triazoles have been researched, due to different needs in terms of structure, functionalization etc.; several of them are currently applied on an industrial scale. This review comprehensively describes and discusses the synthetic methods for the preparation of pyrazolo[5,1-c][1,2,4]triazoles published in the literature from the beginning (ca. 1970) until 2020.

Six new bio-inspired flavylium salts were synthesized and investigated by a combined computational and experimental study for dye-sensitized solar cell applications. The compounds were characterized by FT–IR, UV–Vis, NMR spectroscopy, and LC–MS spectrometry techniques. The pH-dependent photochromic properties of the flavylium dyes were investigated through a UV–Vis spectroscopy study and revealed that they follow the same network of chemical reactions as anthocyanins upon pH changes. The structural and electronic properties of the dyes were investigated using density functional theory (DFT) and time-dependent density functional theory (TD–DFT). Geometry optimization calculation revealed that all dyes, regardless of the specie, flavylium cations or quinoidal bases, present a planar geometry. The photovoltaic performances of the dyes, in both flavylium and quinoidal base forms, were evaluated by the HOMO and LUMO energies and by calculating the light-harvesting efficiencies, the free energy change of electron injection, and the free energy change regeneration. The MO analysis showed that all dyes can inject electrons into the conduction band of the TiO2 upon excitation and that the redox couple can regenerate the oxidized dyes. The results obtained for the free energy change of electron injection suggest that the quinoidal bases should inject electrons into the semiconductor more efficiently than the flavylium cations. The values for the free energy change regeneration showed that the redox electrolyte can easily regenerate all dyes. Dipole moment analysis was also performed. DSSCs based on the dyes, in both flavylium and quinoidal base forms, were assembled, and their photovoltaic performances were evaluated by measuring the open-circuit voltage, the short circuit current density, the fill factor, and the energy conversion efficiency. Results obtained by both experimental and computational studies showed that the overall performances of the DSSCs with the quinoidal forms were better than those obtained with the flavylium cations dyes.

A new azo compound was prepared via the azo coupling reaction between 4-(ethoxycarbonyl)-3-methyl-1H-pyrazole-5-diazonium chloride and 8-hydroxyquinoline (oxine). The ester functional group of the obtained compound was hydrolyzed and thus a new chemical structure with a carboxylic functional group resulted. The structures of the new compounds were fully characterized by: UV–Vis, FT-IR, 1D and 2D NMR spectroscopy, and HRMS spectrometry.

4-(4-Methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-thiol (4) was alkylated to 2-{[4-(4-methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenylethan-1-one (5) in alkaline conditions using 2-bromo-1-phenylethanone. The alkylated compound (5) was reduced at the carbonyl group to the corresponding racemic secondary alcohol with an asymmetric carbon, (R,S)-2-{[4-(4-methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol (6). Both synthesized compounds, ketone (5) and secondary alcohol (6), are new and have not yet been reported in the literature. All the synthesized compounds were characterized by IR, 1D and 2D 1H-1H, 1H-13C and 1H-15N NMR spectroscopy and by elemental analysis.

The novel racemic secondary alcohol (±)-2-{[4-(4-bromophenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]sulfanyl}-1-phenyl-1-ethanol (12) has been successfully synthesized through S-alkylation of 4-(4-bromophenyl)-5-phenyl-4H-1,2,4-triazole-3-thiol (10) in alkaline medium with 2-bromo-1-phenylethanone followed by reduction of the corresponding ketone 11. All the synthesized compounds were characterized by IR, 1D (1H, 13C, DEPT135) and 2D (1H-1H, 1H-13C and 1H-15N) NMR spectroscopy, elemental analysis and HRMS spectrometry.

4-(4-Methoxyphenyl)-5-phenyl--4H-1,2,4-triazole-3-thiol (4) was alkylated to 2-{[4-(-4-methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenylethan-1-one (5) in alkaline conditions using 2-bromo-1-phenylethanone. The alkylated compound (5) was reduced at the carbonyl group to the corresponding racemic secondary alcohol with an asymmetric carbon, (R,S)-2-{[4-(4-methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol (6). Both synthesized compounds, ketone (5) and secondary alcohol (6), are new and have not been reported yet in the literature. All the synthesized compounds were characterized by IR, 1D and 2D NMR 1H-1H, 1H-13C and 1H-15N-NMR spectroscopy and by elemental analysis.

Polarized emission in highly luminescent room temperature columnar metallomesogens based on Zn( ii ) metal centre.

The network of chemical reactions of 2, 6-bis(5-bromo-2-hydroxybenzylidene)cyclohexanone (BHBC) when subjected to light and different pH values has been investigated. The pH dependent species involved in the chemical network have been identified and characterized by NMR and UV-VIS spectroscopy. Direct pH jumps were carried out by adding a strong acid to equilibrated solutions of trans -chalcone (Ct) forming the flavylium cation which was stable only under extremely acidic conditions (pH < 0.5). The single crystal X-ray study and NMR analysis has confirmed the structure of the new flavylium cation. In the case of a reverse pH jump, the Ct species interconverted instantaneously into deprotonated trans -chalcone (Ct^2−) around pH 12. A new colorless compound 3, 11-dibromo-7, 8-dihydro-6 H -chromeno[3, 2- d ]xanthene (B–B) isolated from the equilibrated solution of trans -chalcone species in methanol after long periods of time (100 h) under dark conditions has been isolated and fully characterized by NMR and X-ray diffraction. The rate of the reaction increased when the solution of trans -chalcone was exposed to light and the total conversion of Ct into the spiropyran-like compound (B–B) was achieved in about 30 minutes. The B–B form was stable under neutral and basic conditions, while at low pH values it converts into a cationic AH^+ form.