: Inclinedsquarecavitiesplayacritical role inengineeringapplications,partic ularlyinthermalmanagement,energystorageandelectroniccooling,whereinclinationangles in°uence convectiveheat transfer.This studyexamines conjugate convectiveheat transfer withinaninclinedsquarecavity¯lledwithmicropolarnano°uidsunderatiltedLorentzforce usinga two-phasenano°uidmodel.The systemincludes aheat-generatingporousmedium underthermalnonequilibrium, introducingcomplexdynamics.Factorssuchasthermalbuoy ancy,°uid{solidheattransfercoe±cientandmicropolar°uidpropertiesareanalyzedfortheir impact onheat transfer e±ciency.Methods:The studyuses the¯nitedi®erencemethod (FDM) to solvenonlinear equations governingconvective°owandheat transfer.Physical parameters,includingthermalbuoyancy,micropolarpropertiesandthicknessofthesolidwalls,
A multistep synthesis of novel pyrene-based thiazole moiety been has been realized following some synthetic challenges and complications. The chemical structure of the synthesized compound has been established on the basis of both spectroscopic and analytical tools. Its nucleophilic reactivity with 4,6-dinitrobenzofuroxan (DNBF) has been successfully studied in solution. A kinetic study of the covalent electrophile/nucleophile combination of dinitrobenzofuroxan (DNBF, electrophile) and 4-(pyren-1-yl)thiazol-2-amine (nucleophile) resulting in the formation of the corresponding σ-adduct in solution is reported. The rate constant (k1) of the second-order relating to the C
C bond forming step of this complexation process has been found to fit into the linear correlation log k = sN (N + E), thereby permitting the evaluation of the nucleophilicity parameter (N) of the 4-(pyren-1-yl)thiazol-2-amine. 4-(Pyren-1-yl)thiazol-2-amine has been subsequently ranked according to its reactivity profile on the general nucleophilicity scale developed recently by Mayr et al., leading to an interesting and direct comparison over a large domain of π-, σ-, and n-nucleophiles.
Nowadays, the growth of drug-resistant microbial strains (MDRs) is a serious public health threat worldwide. Moreover, tens of millions of people are annually diagnosed with cancer worldwide, and more than half of patients ultimately die. In the present study, a new series of 2-(4-substituted-thiazol-2-ylamino)acetamides and N-(4-substituted-thiazol-2-yl)acetamides incorporating sulfonamide moieties were designed, synthesized, well-characterized and successfully evaluated for their antimicrobial activity against multidrug resistant strains and screened for cytotoxic activity against normal lung fibroblast (WI-38), human lung carcinoma (A549), and human breast carcinoma (MDA-MB-231) cell lines. Fluorescence-activated cell sorting (FACS) analysis and molecular modeling study were performed to identify the mode of action of the novel synthesized compounds and their binding interactions with the active sites of dihydrofolate reductase enzyme (DHFR).
In this study, a new series of (4-(2,7-dichloro-9H-fluoren-4-yl)thiazol-yl)acetamide derivatives was synthesized, and the new heterocycles were completely characterized, evaluated for their antimicrobial activity, and screened for cytotoxic activity against human lung carcinoma (A-549) and human breast carcinoma (MCF-7) cell lines. A molecular docking study was undertaken to identify the possible mode of action of the synthesized compounds, which suggested binding interactions with the dihydrofolate reductase (DHFR) active sites.
Most of the synthesized compounds displayed meaningful activity against A-549 and MCF-7 cell lines when compared to 5-fluorouracil (5-FU), which was used as a reference drug. Furthermore, some of the prepared compounds exhibited potent antibacterial and antifungal activities. The highly pronounced biological activities of the compounds under investigation offer such species as promising future drug prospects which may find applications in the fields of biological and medicinal sciences.
A kinetic study of the nucleophilic addition reactions of 3-cyanomethylidene-2-oxindoline derivatives with cyclic amines (namely: piperidine, morpholine and pyrrolidine) in MeCN solution at 20 °C is reported. The second-order rate constants showed of this process fit nicely the Brönsted equation log k1 = βnuc pKa + C, allowing the determination of the βnuc parameter in the range of 0.63 < βnuc < 0.77 that indicates that the degree of formation of N–C bond in the transition state is more half complete. Moreover, the analysis of the kinetic measurements based on a good linear log k (20 °C) = sN (E + N) free enthalpy relationship are used to assess the electrophilic reactivity in term of E parameter of these series of 2-oxindoline derivatives Michael acceptors. Of major interest is that the estimated E values were established to cover a domain of reactivity of ~3 units of E, ranging from −17.5 for 2-(5-chloro-2-oxindolin-3-ylidene)malononitrile (the most reactive electrophile) to −20.3 for ethyl 2-(5-chloro-1-methyl-2-oxindolin-3-ylidene)-2-cyanoacetate (the least reactive electrophile). The theoretical reactivity indices ω based on the conceptual Density Functional Theory (DFT) explains correctly the experimental electrophilicity E ordering founded in terms of experimental scales.
Thiazoles, thiazolidinones and azetidinones are highly ranked amongst natural and synthetic heterocyclic derivatives due to their great pharmaceutical potential.
New thiazolidinone and azetidinone class of bioactive agents based on 4-(2,7-dichloro-9H-fluoren-4-yl)thiazole moiety have been successfully synthesized. 4-(2,7-dichloro-9H-fluoren-4-yl)thiazol-2-amine was synthesized and allowed to react with various aryl/heteroaryl aldehydes to afford the corresponding Schiff base intermediates. The target thiazolidinone and azetidinone analogues have derived from Schiff bases by their reactions with thioglycolic acid and chloroacetyl chloride, respectively. The newly synthesized compounds were then evaluated for their antimicrobial activity against some multidrug resistant strains and examined for cytotoxic activity against normal lung fibroblast (WI-38), human lung carcinoma (A549), and human breast carcinoma (MDA-MB-231) cell lines to develop a novel class of fluorene-based bioactive agents. The mode of action and the binding interaction of the synthesized compound with the active sites of dihydrofolate reductase enzyme were well identified by fluorescence-activated cell sorting (FACS) analysis and molecular docking study.
Some of the synthesized compounds showed remarkable activity against A-549 and MDA-MB-231 when compared to Taxol, which was used as a reference drug. 2,7-dichloro-9H-fluorene-based azetidinones are more efficient as antimicrobial and anticancer agents compared to dichloro-9H-fluorene-based thiazolidinones derivatives.
Nucleophilic substitution of carbon-leaving groups (CLGs) and base-catalyzed alcohol dehydration reactions are rare in the organic chemistry literature. Herein, we introduce an unprecedented example of a novel reaction that challenges the poor leaving group abilities of both CLGs and hydroxide ions via a concerted transition state, demonstrating E1cBanion step-2/SNAcyl step-1 reaction mechanism interference, displayed by S1 and S2 scaffolds in an alkaline medium (Schemes 5,8). The work offers swift access to C–C bond hydrolysis in the form of ketone α-hydrolytic cleavage under environmentally convenient conditions. Three reaction products were characterized by single-crystal X-ray crystallography, which supported their computed most stable ring conformer structures. Experimental and DFT evidence evoke fast reaction rates (TS1′, ΔG‡ = 26.8 kcal/mol, Scheme 5 and TS5b, ΔG‡ = 14.9 kcal/mol …
Herein, the presented manuscript provides for an extensive spectrofluorimetric method for micro determination of silver ion. This established method based on the use of the three synthesized 2,6-disubstituted pyridine derivatives (R1, R2 and R3) through exploiting their high fluorescence emission property. A noticeable effect on the fluorescence emission of the reagents after chelation with Ag (I) was monitored. Its noteworthy that the sensitivity and stability of this method was increased by using micellar medium. After chelation with Ag(I), the fluorescence emission of the ligands R1 and R2 were effectively quenched in a regular manner by increasing Ag(I) concentration. In contrast, an increase of the fluorescence intensity for reagent R3 after addition of Ag (I) was observed. The solvatochromism for all reagents under investigation was examined in different solvent. Furthermore, the chelation between Ag(I) and the and designed pyridine reagents was assessed spectrophotometrically. The optimum conditions for the most stable complexes which give a high signal difference were explored and well-determined. The linear range for determination of silver ion were determined and found to be 0.18–1.16, 0.06–0.59 and 0.18–1.43 μg mL−1 for R1, R2 and R3, respectively. The statistical analytical parameters such as LOD, LOQ, SD of slope, SD of intercept and RDS were calculated. In addition, the developed methods were efficaciously applied for determination of Ag(I) in some water samples. These selective complexation methods found to be in good precision compared to official and reported method as revealed F-test.
