Synthesis, photoluminescent, antibacterial activities and theoretical studies of three novel coumarin and dihydropyran derivatives containing a triphenylamine group

Coumarin N-Acylhydrazone Derivatives: Green Synthesis and Antioxidant Potential-Experimental and Theoretical Study

Coumarin N-acylhydrazone derivatives were synthesized in the reaction of 3-acetylcoumarin and different benzohydrazides in the presence of molecular iodine as catalyst and at room temperature. All reactions were rapidly completed, and products were obtained in good to excellent yields. It is important to emphasize that four products were reported for the first time in this study. The obtained compounds were subjected to evaluation of their in vitro antioxidative activity using DPPH, ABTS, and FRAP methods. It was shown that products with a catechol moiety in their structure are the most potent antioxidant agents. The thermodynamic parameters and Gibbs free energies of reactions were used to determine the most probable mechanism of action. The results of in silico examination emphasize the need to take solvent polarity and free radical species into account when examining antiradical action. It was discovered by using computational approaches that HAT and SPLET are competitive molecular pathways for the radical scavenging activity of all compounds in polar mediums, while the HAT is the dominant mechanism in non-polar environments.

Spectroscopic and computational studies of the solid state photophysical properties of a biscoumarin dye

The solid state photophysical properties of the 3,3'-paraphenyl bis[6,8-dimethoxy-2H-chromen-2-one] symmetrical biscoumarin material were investigated by optical spectroscopy techniques and by theoretical calculations. Vibrational analysis using IR absorption and Raman scattering techniques carried out together with DFT theoretical calculations have confirmed the structure of this biscoumarin. The geometry optimization using different functionals reveal a nonplanar equilibrium structure with a dihedral between the phenyl and the pyran rings of about 142°. The UV-Visible absorption measurements and the TDDFT simulation show that this biscoumarin is characterized by a bicomponent feature resulting from ππ* electronic transitions and Intramolecular Charge Transfer (ICT). Solid state photoluminescence showed a bright blue-green emission at 506 nm with a large stokes shift estimated at 146 nm, and the temperature dependence study of this emission reveals two thermal evolution regimes. Finally, these good optical properties, as well as the stability of the emission, make this biscoumarin dye of potential interest for optoelectronic applications.

Synthesis and Evaluation of New Coumarin Derivatives as Antioxidant, Antimicrobial, and Anti-Inflammatory Agents

New pyranocoumarin and coumarin-sulfonamide derivatives were prepared and evaluated for their antioxidant, antimicrobial, and/or anti-inflammatory activities. Coumarin-sulfonamide compounds 8a-d demonstrated significant antioxidant activity, while 7c,d, 8c,d, and 9c,d exhibited antimicrobial activity equal to or higher than the standard antimicrobials against at least one tested microorganism. Regarding the anti-inflammatory testing, pyranocoumarins 2b, 3a,b and 5c and coumarin-sulfonamide compound 9a showed more potent antiproteinase activity than aspirin in vitro; however, five compounds were as potent as aspirin. The anti-inflammatory activity of the promising compounds was further assessed pharmacologically on formaldehyde-induced rat paw oedema and showed significant inhibition of oedema. For in vitro COX-inhibitory activity of coumarin derivatives, pyranocoumarin derivative 5a was the most selective (SI = 152) and coumarin-sulfonamide derivative 8d was most active toward COX-2 isozyme. The most active derivatives met the in silico criteria for orally active drugs; thus, they may serve as promising candidates to develop more potent and highly efficient antioxidant, antimicrobial, and/or anti-inflammatory agents.

Novel 6a,12b-Dihydro-6H,7H-chromeno[3,4-c] chromen-6-ones: Synthesis, Structure and Antifungal Activity

A new series of coumarin derivatives, 7-hydroxy-7-(trifluoromethyl)-6a,12b-dihydro-6H,7H-chromeno[3,4-c]chromen-6-ones 3a–p, were synthesized via Michael addition, transesterification and nucleophilic addition from the reaction of 3-trifluoroacetyl coumarins and phenols in the presence of an organic base. The products were characterized by infrared spectroscopy (IR), hydrogen nuclear magnetic resonance spectroscopy (¹H-NMR), carbon nuclear magnetic resonance spectroscopy (¹³C-NMR) and high-resolution mass spectrometer (HRMS). Single crystal X-ray analysis of compounds 3a and 3n clearly confirmed their assigned chemical structures and their twisted conformations. Compound 3a crystallized in the orthorhombic system, Pbca, in which a = 8.6244(2) Å, b = 17.4245(4) Å, c = 22.5188(6) Å, α = 90°, β = 90°, γ = 90°, v = 3384.02(14) ų, and z = 8. In addition, the mycelial growth rate method was used to examine the in vitro antifungal activities of the title compounds 3a–p against Fusarium graminearum and Fusarium monitiforme at 500 µg/mL. The results showed that compound 3l exhibited significant anti-Fusarium monitiforme activity with inhibitory index of 84.6%.

Antibacterial activities of fluorescent nano assembled triphenylamine phosphonium ionic liquids

Staphylococcus aureus, a Gram positive coccal bacterium is a major cause of nosocomial infection. We report the synthesis of new triphenylamine phosphonium ionic liquids which are able to self-assemble into multiwall nanoassemblies and to reveal a strong bactericidal activity (MIC=0.5mg/L) for Gram positive bacteria (including resistant strains) comparable to that of standard antibiotics. Time kill, metabolism and fluorescence confocal microscopy studies show a quasi-instantaneously penetration of the nanoassemblies inside the bacteria resulting of a rapid blocking (30min) of their proliferation. As confirmed by rezasurin reduction monitoring, these compounds strongly affect the bacterial metabolism and a Gram positive versus Gram negative selectivity is clearly observed. These fluorescent phosphonium ionic liquid might constitute a useful tool for both translocation studies and to tackle infectious diseases related to the field of implantology.