Electrochemical, quantum-chemical and antioxidant properties of antipyrine and its derivatives

Syntheses, crystal structures, Hirshfeld surface analyses and energy frameworks of two 4-amino-anti-pyrine Schiff base compounds: (E)-4-{[4-(di-ethyl-amino)-benzyl-idene]amino}-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one and (E)-4-[(4-fluoro-benzyl-idene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

The title Schiff base compounds, C₂₂H₂₆N₄O (I) and C₁₈H₁₆FN₃O (II), were each synthesized by a single-step condensation reaction. The substituted benzyl-idene ring is inclined to the pyrazole ring mean planes by 22.92 (7)° in I and 12.70 (9)° in II. The phenyl ring of the 4-amino-anti-pyrine unit is inclined to the pyrazole ring mean plane by 54.87 (7)° in I and by 60.44 (8)° in II. In the crystal of I, the mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions to form layers lying parallel to (001). In the crystal of II, the mol-ecules are linked by C-H⋯O and C-H⋯F hydrogen bonds and C-H⋯π inter-actions, thereby forming layers lying parallel to (010). Hirshfeld surface analysis was employed to further qu-antify the inter-atomic inter-actions in the crystals of both compounds.

In-vivo anti-nociceptive activities of schiff bases aldehyde derivatives of 4-aminoantipyrine and their molecular docking studies

In this study, the anti-nociceptive potential of Schiff bases derivatives of 4-aminoantioyrine, (Z)-4-(4-hydroxy-3-methoxybenzylideneamino)-2, 3-dimethyl-1-phenyl-1, 2dihydropyrazol-5-one 1 and (Z)-4-(2-nitrobenzylideneamino)-2, 3-dimethyl-1-phenyl-1-2-dihydropyrazol-5-one 2 were tested in various mice pain models and their binding affinities with different drug targets were evaluated through molecular docking studies. The binding scores were calculated through molecular docking techniques for receptor sensitivity. Acute toxicity test suggests the safety of both compounds up 200 mg/kg. In the righting test, compound 1 and 2 had a significant effect in a dose-dependent manner and showed 59.46% and 48.40% blockade of pain at 150 mg/kg, respectively. In the formalin test, dose-dependently compound 1 showed 52.95% and 62.02% of inhibition in the early and late phase at 150 mg/kg. Similarly, Compound 2 showed 45.74% and 55.95% inhibition in the early and late phases at 150 mg/kg, respectively. In the tail immersion test, both compounds caused significant pain inhibition during various assessment times with maximum effects at 74.94% and 66.80% for 1 and 2 respectively at 150 mg/kg after 120 min. In molecular docking studies, compounds 1 and 2 showed a greater affinity for LOX with a docking score of –6.50 and 6.57 respectively. Similarly, for compounds 1 and 2 the docking was –4.94 and –4.83 with COX-1 while –5.10 and –4.85 with COX-2, respectively. Taken together, both the compounds exhibited marked antinociceptive effects in various pain-induced models possibly mediated by inhibition of LOX and COX pathways.

Phenolic Imidazole Derivatives with Dual Antioxidant/Antifungal Activity: Synthesis and Structure-Activity Relationship

BACKGROUND

Previous publications show that the addition of a phenolic antioxidant to an antifungal agent, considerably enhances the antifungal activity.

OBJECTIVE

Synthesis of novel compounds combining phenolic units with linear or cyclic nitrogencontaining organic molecules with antioxidant/antifungal activity using methodologies previously developed in the group.

METHODS

Several N- [1,2-dicyano-2- (arylidenamino) vinyl]-O-alkylformamidoximes 3 were synthesized and cyclized to 4,5-dicyano-N- (N´-alcoxyformimidoyl)-2-arylimidazoles 4 upon reflux in DMF, in the presence of manganese dioxide or to 6-cyano-8-arylpurines 5 when the reagent was refluxed in acetonitrile with an excess of triethylamine. These compounds were tested for their antioxidant activity by cyclic voltammetry, DPPH radical (DPPH•) assay and deoxyribose degradation assay. The minimum inhibitory concentration (MIC) of all compounds was evaluated against two yeast species, Saccharomyces cerevisiae and Candida albicans, and against bacteria Bacillus subtilis (Gram-positive) and Escherichia coli (Gram negative). Their cytotoxicity was evaluated in fibroblasts.

RESULTS

Among the synthetised compounds, five presented higher antioxidant activity than reference antioxidant Trolox and from these compounds, four presented antifungal activity without toxic effects in fibroblasts and bacteria.

CONCLUSION

Four novel compounds presented dual antioxidant/antifungal activity at concentrations that are not toxic to bacteria and fibroblasts. The active molecules can be used as an inspiration for further studies in this area.

Electropolymerization of cobalto(5,10,15-tris(4-aminophenyl)-20-phenylporphyrin) for electrochemical detection of antioxidant-antipyrine

Porphyrins are a kind of aromatic molecules possessing unique physic-chemical properties. In this manuscript, it was thus utilized to synthesize 5,10,15-tris(4-aminophenyl)-20-phenylporphyrin and cobalto(5,10,15-tris(4-aminophenyl)-20-phenylporphyrin). In addition, conducting cobalto(5,10,15-tris(4-aminophenyl)-20-phenylporphyrin) polymeric films were successfully prepared by electropolymerization approach on glassy carbon electrode in the presence of dimethyl formamide solution and 0.1 M tetra-n-butyl ammonium perchlorate at 100 mV/s scan rate. The synthesized polymeric films were evaluated as the active electrode materials to detect an antioxidant (Antipyrine) present in pharmaceuticals and the limit of detection is ~ 74 μM.

Chemistry of Phosphorus Ylides: Part 41 Synthesis of Antimicrobial Agents from the Reaction of Aminoantipyrine, Coumarin- and Quinoline-carbaldehyde with Phosphacumulene and Phosphaallene Ylides

Pyrrolo-pyrazoles were obtained from the reaction between phosphacumulenes and aminoantipyrine, while the reaction with the phosphaallene (hexaphenylcarbodiphosphorane ylide) afforded the azaphosphole and pyrazolo-phosphanylidene. The aminocoumarin carbaldehyde gave the chromeno-phosphanylidene and the chromeno-pyridinone, when it was allowed to react with phosphacumulenes. The reaction of chloroquinoline carbaldehyde with the phosphacumulenes, gave chloroquinoline phosphanylidenecyclobutane, while the reaction with phosphaallene resulted in the formation of oxaphosphetane, phosphanylidene ethenyl- and oxaphosphetyl-quinoline. The structure of cyclobutanedione was confirmed by X-ray crystallography. The antimicrobial activity of the new compounds is also reported.

Synthesis, structure and photoresponsive properties of 4-(3-fluorobenzylideneamino)antipyrine

Organic compounds are attracting greater attention largely in the recent years owing to their potential applications in the functional materials. Herein we reported the structural and photophysical properties of 4-(3-fluorobenzylideneamino)antipyrine. The studied molecule adopts a trans configuration about the imine bond, and forms a non-planar molecular device consisted of two effectively conjugated π-electron moieties. The stronger vibrational and nonlinear optical activities are tightly related to the molecular structural characteristics revealed by the analysis on vibrational modes and frontier molecular orbitals. The intramolecular electrons can be separated by the electron-transporting with specified photon-absorbing theoretically. The total molecular dipole moment, mean linear polarizability and first-order hyperpolarizability calculated at B3LYP/6-31G(d) level are 1.5390 Debye, 35.6075 Å(3) and 1.5391×10(-29) cm(5)/esu, respectively. The reported results indicate that the compound is a promising candidate of photoresponsive materials.

Molecular structure and vibrational spectra studies on antipyrine derivative, 4-(2,3,4-trihydroxybenzylideneamino) antipyrine

The molecular geometry, theoretical harmonic frequencies and infrared intensities of 4-(2,3,4-trihydroxybenzylideneamino) antipyrine (THBAP) were calculated using different density functional methods (LSDA, mPW1PW91, B3LYP and HCTH) with various basic sets, including 3-21G, 6-311G, LanL2DZ, and SDD. The purpose of this research is to compare the performance of different density functional theory (DFT) methods at different basis sets in predicting geometry and vibration spectrum of THBAP. The optimized geometric band lengths and bond angles obtained by using mPW1PW91 at both LanL2DZ and SDD basic sets show the best agreement with the experimental data. A comparison between the observed fundamental vibrational frequencies of THBAP and the calculated results has been made and the result indicates that the mPW1PW91/6-311G level is superior to all the remaining levels for predicting all the vibration spectra on average for THBAP.

Synthesis, structure, photo-responsive properties of 4-(2-fluorobenzylideneamino)antipyrine: a combined experimental and theoretical study

In this work, 4-(2-fluorobenzylideneamino)antipyrine (FBIAAP) was synthesized and characterized by elemental analysis, XRD, FT-IR, FT-Raman and UV-Vis techniques as well as density functional calculations. The studied molecule adopts a trans configuration about the imine CN bond, and adjacent molecules are linked through two kinds of weak hydrogen bonds to form supramolecular layered structures along the ab plane. Vibrational spectral analyses show that the benzene moiety directly attached to the central pyrazoline shows good vibrational isolation from the other moiety of pyrazole-imino-benzene presenting good vibrational resonances. UV-vis absorption bands mainly belong to n→π and π→π according to the electron transfer orbital assignments for the electron absorption spectrum of FBIAAP. The first-order hyperpolarizability of FBIAAP is 44.9 times that of urea theoretically. In addition, the thermodynamic properties were also obtained theoretically from the harmonic frequencies of the optimized structure.

Chemical and biological evaluation of some new antipyrine derivatives with particular properties

Starting from 4-amino-antipyrine, six new compounds were synthesized and characterized. The new compounds contain moieties with particular properties, such are ionophore (benzo-15-crown-5), fluorescent (nitrobenzofurazan), stable free radical (nitroxide), or other types of biological active residues, like nitroderivatives, antipyrine or isoniazid residues. They were fully characterized by appropriate means ((1)H and (13)C NMR, IR, UV-Vis, fluorescence, EPR, elemental analysis) and some of their biological properties were evaluated. Hydrophobicity (R(M0), log P), total antioxidant capacity (TAC), and antimicrobial properties are also presented and discussed.

4-[(1-Hy-droxy-2-naphth-yl)methyl-ene-amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

The title anti-pyrine derivative, C(22)H(19)N(3)O(2), was synthesized by the reaction of 4-amino-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one and 1-hy-droxy-naphthalene-2-carbaldehyde in methanol solution. As expected, the compound adopts a trans configuration about the central C=N bond. The N atom is involved in an intra-molecular O-H⋯N bond which stabilizes the mol-ecular configuration. In the crystal structure, adjacent mol-ecules stack with no short contacts.

Experimental and theoretical studies on o-, m- and p-chlorobenzylideneaminoantipyrines

Three antipyrine derivatives of o-, m- and p-chlorobenzylideneaminoantipyrines were characterized by spectral techniques and density functional calculations. The optimized configurations are very close to the XRD values and are used as foundations to investigate the molecular properties. The spectral assignments were attempted to ascribe to the vibrational modes of the detailed substructures with the aid of theoretical calculations because of the satisfactory consistencies between the experimental and theoretical spectra for each of the studied compounds. Raman spectral ascriptions represent that the pi-conjugated moieties linked by Schiff base imines are responsible for the excellent Raman scattering activities of these compounds. The linear polarizabilities and first hyperpolarizabilities of the studied molecules indicate that the compounds are good candidates of nonlinear optical materials. The statistical thermodynamic functions and their correlations with temperatures obtained from the theoretical vibrations are similar to each other among the isomers.

Experimental and theoretical studies on vibrational spectra of 4-(2-furanylmethyleneamino)antipyrine, 4-benzylideneaminoantipyrine and 4-cinnamilideneaminoantipyrine

This work deals with the IR and Raman spectroscopy of 4-(2-furanylmethyleneamino) antipyrine (FAP), 4-benzylideneaminoantipyrine (BAP) and 4-cinnamilideneaminoantipyrine (CAP) by means of experimental and quantum chemical calculations. The equilibrium geometries, harmonic frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-31G(d) basis set. The comparisons between the calculated and experimental results covering molecular structures, assignments of fundamental vibrational modes and thermodynamic properties were investigated. The optimized molecular geometries have been compared with the experimental data obtained from XRD data, which indicates that the theoretical results agree well with the corresponding experimental values. For the three compounds, comparisons and assignments of the vibrational frequencies indicate that the calculated frequencies are close to the experimental data, and the IR spectra are comparable with some slight differences, whereas the Raman spectra are different clearly and the strongest Raman scattering actives are relative tightly to the molecular conjugative moieties linked through their Schiff base imines. The thermodynamic properties (heat capacities, entropies and enthalpy changes) and their correlations with temperatures were also obtained from the harmonic frequencies of the optimized structures.

Experimental and theoretical studies on 4-(2,4-dichlorobenzylideneamino)antipyrine and 4-(2,6-dichlorobenzylideneamino)antipyrine

Two antipyrine derivates, with the same formula C(18)H(15)Cl(2)N(3)O, are structurally similar Schiff bases derived from the condensation of 2,4-dichlorobenzaldehyde or 2,6-dichlorobenzaldehyde and 4-aminoantipyrine in methanol solutions. The compounds were characterized by elemental analysis, FT-IR, FT-Raman and UV-vis techniques. Density functional calculations were performed to further optimize and characterize them. The calculated results indicate that the theoretical values show good agreements with experimental ones. They are similar in their IR spectra and different in their Raman spectra. The detailed vibrational and UV-vis absorption spectra of the compounds have been ascribed to their corresponding molecular structures and electrons orbital transitions. The statistical thermodynamic functions and their correlations with temperatures of the title compounds have been obtained from their theoretical vibrations of the optimized structures. The nonlinear optical and UV-vis properties indicate that the compounds are the promising photoelectronic materials.

Antioxidant redox sensors based on DNA modified carbon screen-printed electrodes

Antioxidant redox sensors based on DNA modified carbon screen-printed electrodes were developed. The carbon ink was doped with TiO2 nanoparticles, onto which double-strand DNA was adsorbed. A redox mediator, namely, tris-2,2'-bipyridine ruthenium(II) [Ru(bpy)3(2+)] was electrooxidized on the electrode surface to subsequently oxidize both the adsorbed ds-DNA and the antioxidants in solution. The resulting oxidation damage of the adsorbed ds-DNA was then detected by square wave voltammetry in a second solution containing only Ru(bpy)3Cl2 at a low concentration (microM). A kinetic model was developed to study the protecting role of antioxidants in aqueous solutions. The electrochemical sensor has been applied to evaluate the redox antioxidant capacity of different molecules.