Omar Khoumeri

Influence of Silver Nanoparticles on 2,3-Bis(Chloromethyl)Anthracene-1,4,9,10-Tetraone

Size effect of silver nano particles on the photophysical properties of 2,3-bis(chloromethyl)anthracene-1,4,9,10-tetraone (BCMAT) have been investigated using optical absorption and fluorescence emission techniques. Silver NPs of different sizes have been prepared by two different methods. Quenching of fluorescence of BCMAT has been found to increase with decrease in the size of the silver NPs. Stern–Volmer quenching constants have also been calculated.

Synthesis of Novel Highly Functionalized 4-Thiazolidinone Derivatives from 4-Phenyl-3-thiosemicarbazones

We present herein the synthesis in good yields of two series of highly functionalized thiazolidinone derivatives from the reactions of various 4-phenyl-3-thio-semicarbazones with ethyl 2-bromoacetate and diethyl acetylenedicarboxylate, respectively.

Synthesis of New Quinoxalines Containing an Oxirane Ring by the TDAE Strategy and in Vitro Evaluation in Neuroblastoma Cell Lines

Neuroblastoma is an aggressive pediatric malignancy with significant chemotherapeutic resistance. In order to obtain new compounds active on neuroblastoma cell lines, we investigated the reactivity of carbanion formed via TDAE in quinoxaline series. The new synthesized compounds were tested for their anti-proliferative activity on two neuroblastoma cell lines, and seven oxirane derivatives obtained interesting activities.

Adsorption of N-(1-(2-bromophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide on silver nanoparticles: SERS investigation.

SERS provides essential data regarding the interaction of molecules in drugs with DNA. In the present study silver nanoparticles were synthesized using a solution combustion method with urea as fuel. The prepared silver nanoparticles are rod like structure. Surface-enhanced Raman scattering (SERS) of N-(1-2-bromophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide (BrS) adsorbed on the silver nanoparticle was studied. The nRs and Raman spectral analysis reveal that the BrS adsorbed tilted orientation on the silver surface. Vibrational modes of nRs along with HF calculations are also performed to study the HOMO and LUMO behavior and vibrational features of BrS.

Spectroscopic studies of 1,4-dimethoxy-2,3-dimethylanthracene-9,10-dione on plasmonic silver nanoparticles.

Silver nanoparticles (Ag NPs) of different sizes from 7nm to 22nm have been prepared by simple Dirk and Charles chemical method and characterized using UV-vis spectroscopy and high resolution transmission electron microscopy (HRTEM). Fluorescence quenching of 1,4-dimethoxy-2,3-dimethylanthracene-9,10-dione (DMDMAD) by silver nanoparticles has been investigated by fluorescence spectroscopy to understand the role of quenching mechanism. Furthermore, the intensity of DMDMAD fluorescence emission peak decreases with decrease in the size of the Ag NPs. The fluorescence quenching rate constant and association constant for above system were determined using Stern-Volmer and Benesi-Hildebrand plots. The mechanism of DMDMAD fluorescence quenched by Ag NPs was discussed according to the Stern-Volmer equation. It has been observed that the quenching due to Ag NPs proceeds via dynamic quenching process. The distance between DMDMAD (donor) to Ag NPs (acceptor) and the critical energy transfer distance were estimated based on the Förster Resonance Energy Transfer (FRET) theory.

Synthesis and Anti-Platelet Activity of Thiosulfonate Derivatives Containing a Quinone Moiety

Thiosulfonate derivatives based on quinones were synthesized for studying “structure-activity relationship” compounds with an acylated and a free amino-group. Anti-platelet activity of the synthesized compounds was determined and the influence of substituents on the activity of the derivatives was assessed.

TDAE Strategy in the Benzoxazolone Series: Synthesis and Reactivity of a New Benzoxazolinonic Anion

We describe an original pathway to produce new 5-substituted 3-methyl-6-nitro-benzoxazolones by the reaction of aromatic carbonyl and α-carbonyl ester derivatives with a benzoxazolinonic anion formed exclusively via the TDAE strategy.

TDAE Strategy for the Synthesis of 2,3-Diaryl N-Tosylaziridines

We report herein an original and rapid synthesis of 2,3-diaryl N-tosylaziridines by TDAE strategy starting from ortho- or para-nitro(dichloromethyl)benzene derivatives and N-tosylimines. A mixture of cis/trans isomers was isolated from 1-(dichloromethyl)-4-nitrobenzene, whereas only trans-aziridines were obtained from ortho-nitro derivatives.

Mn(OAc)3 catalyzed intermolecular oxidative peroxycyclization of naphthoquinone

Manganese(III) acetate-mediated peroxycyclization between 2-hydroxy-3-methylnaphthoquinone and various alkenes was performed to obtain dihydronaphtho[2,3-c][1,2]dioxine-5,10(3H,10aH)-diones. The reactivity of symmetrical or unsymmetrical 1,1-disubstituted alkenes and monosubstituted alkenes allowed the synthesis of more than 50 original molecules. Focusing on the excellent reactivity of 2-hydroxy-3-methylnaphthoquinone, we describe the first example of Mn(OAc)3 reactivity with nitro-substituted alkenes. The scope, limitations and stereochemistry of the products synthesized are discussed. Starting from monosubstituted alkenes, the instability of a pair of diastereoisomers was observed, leading to ring opening.

Synthesis and Conformational Analysis of [3-(6-Chloropyridazin-3-yl)-3,4-Dihydropyridazino[4,5-b]Quinoxalin-2(1Н)-yl](Phenyl)Methanone

[3-(6-Chloropyridazin-3-yl)-3,4-dihydropyridazino[4,5-b]quinoxalin-2(1H)-yl](phenyl)methanone has been synthesized and its two stable forms were isolated. For the establishment of their structures, B3LYP geometry and energy and GIAO/B3LYP NMR calculations of possible conformers using the polarizable continuum model were performed. The differences in calculated spectra allow attributing calculated structures and obtained substances by their 1H and 13C NMR. The conformer ratio correlates with their calculated Gibbs energies.