A selective turn-on fluorescent chemosensor 1,1-diaminoazine for azinphos-methyl

Financiaciado para publicación en acceso aberto: Universidade de Vigo/CISUGDetection of organophosphorus pesticides (OPPs) is an important challenge in environmental chemistry, because their exposure to humans can cause severe health problems. In the current study, organic nanoparticles of (E)-(4-chlorophenyl)-1,1-diamino-2,3-diazabutadiene were developed using eco-friendly approach which was found to be in the range of 15–20 nm. These synthesized species exhibited both U.V. Visible and “turn-on” fluorescence responses in aqueous media for the selective detection of the extremely hazardous pesticide azinphos-methyl. These organic nanoparticles also exhibit a good linear relationship in the range of 1–100 μM and the limit of detection (LOD) is 7.4 µM. The selective fluorescence response was also observed in RO water, tap water and orange juice. The FT-IR and DFT studies helped in identifying the specific H-bonding interactions responsible for the selective detection of Azinphos-methylDepartment of Science and Technology, New-Delhi, India | Ref. SP/YO/2021/231

2-(4-Chloro­benzo­yl)-1-(diamino­methyl­ene)hydrazinium chloride monohydrate

In the cation of the title compound, C8H10ClN4O+·Cl−·H2O, the guanidinium group is planar (maximum deviation = 0.0001 Å) and nearly perpendicular to carboxamide group, making a dihedral angle of 87.0 (3)°. The N atoms of the guanidine fragment have a planar trigonal configuration and the N atom of the carboxamide group adopts a pyramidal configuration. In the crystal structure, inter­molecular N—H⋯O, N—H⋯Cl and O—H⋯Cl hydrogen bonds link the cations, anions and water mol­ecules into layers parallel to the bc plane

Structure and dynamics of reentrant nematics: Any open questions after almost 40 years?

Liquid crystals have attracted enormous interest because of the variety of their phases and richness of their application. The interplay of general physical symmetries and specific molecular features generates a myriad of different phenomena. A surprising behavior of liquid crystals is the reentrancy of phases as temperature, pressure, or concentration are varied. Here, we review the main experimental facts and the different theoretical scenarios that have guided the understanding of bulk reentrant nematics. Recently, some computer simulations of a system confined to nanoscopic scales have found new dynamical features of the reentrant nematic phase. We discuss this prediction in relation with the available experimental evidence on reentrant nematics and with the dynamics of liquids in strongly confined environments

Comparative 3D QSAR study on β1-, β2-, and β3-adrenoceptor agonists

A quantitative structure–activity relationship study of tryptamine-based derivatives of β1-, β2-, and β3-adrenoceptor agonists was conducted using comparative molecular field analysis (CoMFA). Correlation coefficients (cross-validated r2) of 0.578, 0.595, and 0.558 were obtained for the three subtypes, respectively, in three different CoMFA models. All three CoMFA models have different steric and electrostatic contributions, implying different requirements inside the binding cavity. The CoMFA coefficient contour plots of the three models and comparisons among these plots provide clues regarding the main chemical features responsible for the biological activity variations and also result in predictions which correlate very well with the observed biological activity. Based on the analysis, a summary regeospecific description of the requirements for improving β-adrenoceptor subtype selectivity is given

Theoretical studies on nitro substitution in keto-enol and imine-enamine tautomeric processes

100-105Ab initio studies on the keto-enol tautomerism in nitroacetaldehyde and imine-enamine tautomerism in nitroacetaldimine are carried out by performing optimizations at HF/6-31G* and MP2/6-31G* levels. Final energies are obtained by performing MP4(SDTQ) single point energies on the MP2/6-31G* geometries. The stabilities of the resultant nitrovinylalcohol and nitrovinyalamine have been estimated by studying the 1,5 hydrogen shift in these molecules. The 1,3-hydrogen shifts in nitroacetaldehyde and nitroacetaldimine to give acinitro tautomers are also analysed. The enol and enamine tautomers are stabilized due to intramolecular hydrogen bond upon nitro substitution. The tautomer energy differences are reduced in keto-enol tautomerism by about 8.7 kcal/mol because of nitro substitution. The generally unstable enamine became more stable than imine by 2.5 kcal/mol on nitro substitution