1-(4-Chloro-phen-yl)-1H-1,2,4-triazol-5(4H)-one.

In the title compound, C8H6ClN3O, the dihedral angle between the 1,2,4-triazole and benzene rings is 4.60 (9)° and an intra-molecular C-H⋯O inter-action closes an S(6) ring. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R 2 (2)(8) loops and C-H⋯O inter-actions link the dimers into [100] chains. Weak π-π stacking inter-actions [centroid-centroid distance = 3.644 (1) Å] are also observed.

Serendipitous Formation of 2H-Pyrazolo[3,4-d]pyridazin-7(6H)-ones from 3-Arylsydnones.

Fused nitrogen heterocyclesnamely, pyrazolo[3,4-d]pyridazin-7(6H)-ones have been obtained by exploiting the 1,3-dipolar nature of N-arylsydnones, from hydrazones of 3-aryl-4-acetylsydnones via the Vilsmeier-Haack strategy. Facile intramolecular nucleophilic addition followed by CO2 elimination under reflux or upon microwave irradiation was presented. Plausible mechanisms for the formation of the title compounds are proffered. Structure confirmatory evidence came from single-crystal X-ray crystallography.

Synthesis, Photophysical and Computational Study of Novel Coumarin-based Organic Dyes.

A series of novel coumarin pyrazoline moieties combined with tetrazoles, 3-(1-phenyl-4-(1H-tetrazol-5-yl)-1H-pyrazol-3-yl)-2H-chromen-2-one, 6-chloro-3-(1-phenyl-4-(1H-tetrazol-5-yl)-1H-pyrazol-3-yl)-2H-chromen-2-one, 6-bromo-3-(1-phenyl-4-(1H-tetrazol-5-yl)-1H-pyrazol-3-yl)-2H-chromen-2-one and 6-bromo-3-(1-(4-bromophenyl)-4-(1H-tetrazol-5-yl)-1H pyrazol-3-yl)-2H-chromen-2-one7(a-d), were designed and synthesized. Single crystal X-ray diffraction and their interactions were studied by Hirshfeld surface analysis. Thermal stabilities and electrochemical properties of these compounds were examined from differential scanning calorimetry (DSC), thermogravimetric (TGA) and cyclic voltammetric (CV) studies. Their spectroscopic properties were analyzed in various alcohols and general solvents by UV-Vis absorption, fluorescence and time-resolved spectroscopy. In addition, the ground and excited state electronic properties were investigated using density functional theory (DFT). The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and energy band gap (Eg ) values have revealed the effect of substitution of halogens. The substitution has equally affected the ground and excited states of 7(a-d) compounds. The solvatochromism on absorption, fluorescence spectra and fluorescence lifetimes of these compounds was investigated. All these results showed the chromen-2-one of pyrazoline tetrazole derivatives could play an important role in photonic and electronic devices.

Design and Microwave Assisted Synthesis of Coumarin Derivatives as PDE Inhibitors.

Coumarins appended to benzimidazole through pyrazole are designed and synthesized using microwave irradiation. These compounds were analyzed for phosphodiesterase (PDE) inhibition indirectly by motility pattern in human spermatozoa. Some of the synthesized compounds, namely, 5d, 5e, 5f, 5g, 5h, and 5k, have exhibited potent inhibitory activity on PDE.