Search results for "Substituents"
showing 9 items of 9 documents
Strategic Syntheses of Vine and Wine Resveratrol Derivatives to Explore their Effects on Cell Functions and Dysfunctions
2018
Trans-resveratrol, the most well-known polyphenolic stilbenoid, is found in grapes and accordingly in wine and it is considered to be beneficial for human health, especially towards the aging-linked cell alterations by providing numerous biological activities, such as anti-oxidant, antitumoral, antiviral, anti-inflammatory, neuroprotective, and platelet anti-aggregation properties. Although trans-resveratrol is a promising molecule, it cannot be considered as a drug, due to its weak bio-availability and fast metabolism. To overcome these weaknesses, several research teams have undertaken the synthesis of innovative trans-resveratrol derivatives, with the aim to increase its solubility in wa…
Preparation and molecular structures of N′-(2-heteroarylmethylidene)-3-(3-pyridyl)acrylohydrazides
2018
Abstract The crystal and molecular structures of N′-(2-furylmethylidene)-3-(3-pyridyl)acrylohydrazide and N′-(2-thienylmethylidene)-3-(3-pyridyl)acrylohydrazide are reported, and the influence of the type of the heteroatom on the aromaticity of the aromatic rings is discussed. Both molecules are nearly planar. The geometry of the acrylohydrazide arrangement is comparable to that of homologous compounds. Density functional theory (DFT) calculations were performed in order to analyze the changes in the geometry of the studied compounds in the crystalline state and for the isolated molecule. The most significant changes were observed in the values of the N–N and C–N bond lengths. The harmonic …
Substituent effect on the redox potential of substituted (aryl)(2-nitrobenzo[ b ]thiophen-3-yl)amines
2001
Abstract The electronic effect of some meta- or para-substituents on the reduction of the title compounds has been investigated. The reversible reduction potential values of these compounds have been evaluated by cyclic voltammetry at a mercury electrode in 0.1 M tetraethylammoniumtetrafluoroborate, dimethylsulfoxide solutions. The substituent effect depends on both its nature and its position. The reduction potential values of the derivatives studied have been correlated with the Hammett substituent constants.
Effect of Substituents at Imide Positions on the Laser Performance of 1,7-Bay-Substituted Perylenediimide Dyes
2021
Perylenediimide (PDI) compounds with no substituents in their core are widely used as the active units of thin-film organic lasers. Recently, bay-substituted PDIs (b-PDIs) bearing two sterically hindering diphenylphenoxy groups at the 1,7-bay positions have received great attention because they show red-shifted emission with respect to bay-unsubstituted PDIs, while maintaining high photoluminescence (PL) quantum yields and low amplified spontaneous emission (ASE) thresholds even at high doping rates. However, their ASE photostability is relatively low compared to that of state-of-the-art PDIs. Thus, the design of b-PDIs with improved ASE photostability remains a challenge. Here, the synthes…
Carborane-stilbene dyads: influence of substituents and cluster isomers on the photoluminescence properties
2017
Two novel styrene-containing meta-carborane derivatives substituted at the second carbon cluster atom (Cc) with either a methyl (Me), or a phenyl (Ph) group, are introduced herein alongside with a new set of stilbene-containing ortho- (o-) and meta- (m-) carborane dyads. The latter set of compounds has been prepared from styrenecontaining carborane derivatives via Heck coupling reaction. High regioselectivity has been achieved for these compounds by using a combination of palladium complexes [Pd2(dba)3]/[Pd(t-Bu3P)2] as a catalytic system, yielding exclusively E isomers. All compounds have been fully characterized and the crystal structures of seven of them analyzed by X-ray diffraction. Th…
On the rearrangement of some Z-arylhydrazones of 3-benzoyl-5-phenylisoxazoles into 2-aryl-4-phenacyl-2H-1,2,3-triazoles: a kinetic study of the subst…
2015
Abstract The rearrangement of eight new Z -arylhydrazones of 3-benzoyl-5-phenylisoxazoles ( 3d – k ) into the relevant 2-aryl-4-phenacyl-2 H -1,2,3-triazoles ( 4d – k ) in dioxane/water solution at different proton concentrations has been quantitatively studied in a wide temperature range (293–333 K). The data collected together with some our previous ones on compounds 3a – c have allowed a deep study of the substituent effects on the course of the rearrangement, thus increasing our knowledge on the Boulton–Katritzky reactions in isoxazole derivatives and on the temperature effects on free energy relationships.
Stacking of Sterically Congested Trifluoromethylated Aromatics in their Crystals – The Role of Weak F···π or F···F Contacts
2020
European journal of organic chemistry : EurJOC 2020(38), 6073-6077 (2020). doi:10.1002/ejoc.202001008
Syntheses of Trifluoroethylated N-Heterocycles from Vinyl Azides and Togni’s Reagent Involving 1,n-Hydrogen-Atom Transfer Reactions
2020
2,2,2-Trifluoroethyl-substituted 3-oxazolines, 3-thiazolines, and 5,6-dihydro-2H-1,3-oxazines have been obtained by reacting substituted vinyl azides with a combination of Togni’s reagent and substoichiometric amounts of iron(II) chloride. The results of density functional theory calculations support the proposed mechanism involving 1,n-hydrogen-atom transfer reactions. peerReviewed
Substituent effects on the mechanism changeover in a multipathway reaction: A model for the behavior of biological systems?
2009
By studying the rearrangement in dioxane/water of a series of (Z)-arylhydrazones of 5-amino-3- benzoyl-1,2,4-oxadiazole (1a-k) into the relevant (2-aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas (2a-k) in a wide range of pS + (an operational scale of proton concentration in the mixed solvent used; dioxane/water, 1:1, v:v), the occurrence of three different reaction pathways (specific-acid- catalyzed, uncatalyzed, and general-base-catalyzed) for the relevant SNi process has been recently enlightened. The significantly different substituent effects on the three pathways cause some crossovers in the log kA,R versus pS + plots. Both the pS + value at which the crossover occurs and the width of the u…