Physicochemical studies of a new series of aryloxide complexes,Na2[Co(OAr)4].nTHF

Summary By the interaction of anhydrous CoBr₂ or CoBr₂·2THF with different sodium aryloxides, a new series of complexes of general formula Na₂[Co(OAr)₄]·nTHF (OAr =o-nitro,o-chloro,o-bromo,m-chloro,p-bromo, 2,4-dichloro, 2,6-dichloro, or 2,4-dimethylphenoxide;n = 1, 3, 4 or 5) were prepared and characterized by physicochemical means. The electronic spectra and magnetic measurements suggest a tetrahedral geometry for cobalt(II). Heating the complexes led to reversible loss of THF with an accompanying colour change.     

Synthesis of new bicarbazole-linked triazoles as non-cytotoxic reactive oxygen species (ROS) inhibitors

Abstract

Carbazole analogs 3 and 4 and a new library of bicarbazole-linked triazoles 6–11 were prepared via new synthetic methodology. Metal-catalyzed oxidative coupling reaction was utilized for the synthesis of bicarbazole acetylene 4 and different metals (Zn⁺², Co⁺², Fe⁺³, Ni⁺², Cu⁺², Mn⁺²) as catalyst were screened. Only Fe-catalyzed reaction was found to be excellent and gave homocoupled product 4. Cu-catalyzed 1,3-dipolar cycloaddition was also utilized to install triazole moiety for the synthesis of hybrid molecules 6–11. Based on reported anti-inflammatory activity of carbazole and triazole scaffolds, all compounds were screened for their reactive oxygen species (ROS) inhibitory potential. Results from these studies revealed triazole 9 as most active compound (IC₅₀ value of 7.6?±?0.1?µg/mL on human whole blood and 2.7?±?0.09?µg/mL on isolated neutrophils) using ibuprofen as a standard. Therefore, class described herein can serve as attractive structural element for further studies on ROS inhibition.     

Enamine Rearrangement of Pyridinium Salts to Indole Ring: A Combined Experimental and Molecular Modeling Study

N‐Alkyl pyridinium ( II ) and N‐alkyl isoquinolinium salts V undergo cyclization reaction when heated with sodium bicarbonate to give the corresponding indolizine derivatives III and VIa , VIb , VIc , VId , VIe , respectively, which undergo ring opening and recyclization reactions when heated with aqueous sodium hydroxide to give the corresponding indole derivatives IV and IXa , IXb , IXc , IXd , IXe , respectively. Molecular modeling tools including Molecular Mechanics using Augmented MM3 parameters followed by geometry optimization calculations in MO‐G using PM3 parameters were performed to gain better understanding and more insights on the thermodynamic properties of the recyclization reactions of compounds IIa , IIb , IIc , IId , IIe , IIf , IIg to the corresponding IIIa , IIIb , IIIc , IIId , IIIe , IIIf , IIIg and IIIa , IIIb , IIIc , IIId , IIIe , IIIf , IIIg to the corresponding IVa , IVb , IVc , IVd , IVe , IVf , IVg . The results were in excellent agreement with the experimental data and hence were proven to be a good tool in explaining different yields % because of the steric and electronic effects of electron‐withdrawing groups on the reactivity of the pyridine ring for nucleophilic attack.     

An evaluation of the radial part of numerical integration commonly used in DFT

Recently, Gill and Chien introduced a new radial quadrature for multiexponential integrands (MultiExp grid) to deal with the radial part of the numerical integration. In this article, the MultiExp grid is studied and used to integrate the charge density. The MultiExp grid, along with an optimal pruning scheme, performed very well both in terms of accuracy and efficiency compared to other radial mappings commonly used in Density Functional Theory.     

An efficient sonochemical oxidation of benzyl alcohols into benzaldehydes by FeCl3/HNO3 in acetone

Sonochemical oxidation of benzyl alcohols into corresponding aldehydes by FeCl(3)/HNO(3) in acetone at room temperature has been reported. All substrates give good yield of the products within 10-25 min. The reaction of selected substrates were also studied under reflux and at the room temperature. Further, various Lewis acids were used to evaluate their catalytic efficacy.     

Substituted pyridopyrimidinones. Part 5. Behavior of 2-hydroxy-4-oxo-4<Emphasis Type="Italic">H</Emphasis>-pyrido[1,2-<Emphasis Type="Italic">α</Emphasis>]pyrimidine-3-carbaldehyde in nucleophilic condensation reactions

Reactivity of 2-hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carbaldehyde (I) towards N- and C-nucleophiles was described. A series of new enaminones II–III, Schiff’s base IV, and hydrazinomethylenediketones V–VIII and X were prepared in good yields. Cyclization of compounds X was achieved by an action of acetic acid to give pyrazolo[3,4-d]pyrido[1,2-a]pyrimidines XI. Base catalyzed Knoevenagel condensation of aldehyde I with some active methyl and methylene compounds led to a series of chalcone-like derivatives XII, XV, XVII, XX, XXIII, XXV, XXVII, XXIX, XXXI, XXXII, and XXXV, in fair yields. Cyclization of enones XII, XV, and XX with hydrazine gave novel heterocyclyl substituted pyrazoles XIII, XVII, and XXI, respectively. Pyrano[2,3-d]pyrido[1,2-a]pyrimidine-2,5-diones XXXIII, XXXIV, and XXXVI derivatives were obtained via cyclization of their respective enone derivatives.     

General boundary stabilization of memory type in thermoelasticity of type III

In this paper, we consider a multi-dimensional system of thermoelasticity type III with a viscoelastic damping acting on a part of the boundary. We establish a general decay result, from which the usual exponential and polynomial decay rates are only special cases.     

Imidazole-modified porphyrin as a pH-responsive sensitizer for cancer photodynamic therapy

5,10,15,20-Tetrakis(N-(2-(1H-imidazol-4-yl)ethyl)benzamide)porphyrin produced twice as many singlet oxygen ((1)O(2)) molecules at pH 5.0 (quantum yield 0.53 ± 0.01) than at pH 7.4, whereas the (1)O(2) quenching rate was reduced by a factor of 2.5 for a pH change from 7.4 to 5.0.