Dapson in Heterocyclic Chemistry,Part II: Antimicrobial and Antitumor Activities of Some Novel Sulfone Biscompounds Containing Biologically Active Thioureido,Carbamothioate, Quinazoline,Imidazolidine, and Thiazole Moieties

The reaction of 4,4′-diisothiocyanato-1,1-diphenylsulfone 2 with aromatic amines and phenol derivatives afforded the corresponding thioureio derivatives 3–9 , respectively. Also, the reaction of 2 with catechol gave the corresponding carbamothioate derivative 11. Quinazoline derivatives 14 and 15 were obtained in good yield via reaction of 2 with anthranlic acid derivatives. Imidazolidine biscompounds 16 and 17 were readily synthesized from the reaction of 2 with N-(4-substituted-phenyl)cyanothioformanilides. The structure of the products was confirmed from elemental analysis as well as spectral data. Most of the synthesized compounds showed remarkable antimicrobial activity compared with chloramphenicol and Grisofluvine as positive controls. Compound 6 was almost as active an antitumor agent as the reference drug Doxorubicin.     

Thermal decomposition of lanthanide(III) complexes of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand

The thermal decomposition of lanthanide complexes, with a general formula: [LnL(NO₃)₂](NO₃), where Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, and Er; and L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand, was studied by thermogravimetric (TG) and derivative thermogravimetric (DTG) techniques. The TG and DTG data indicated that all complexes are thermostable up to 398 K. The thermal decomposition of all Ln(III) complexes was a two-stage process and the final residues were Ln₂O₃ (Ln = La, Nd, Sm, Gd, Dy, Er), Tb₄O₇, and Pr₆ O₁₁. The activation energies of thermal decomposition of the complexes were calculated from analysis of the TG-DTG curves using the Kissinger, Friedman, and Flynn-Well-Ozawa methods.     

Synthesis of 3-(Tetritol-1-YL)-6-Phenyl-1,2,4-Triazolo[3,4-a]Phthalazines and Conformational Analysis of their Acetates

ABSTRACT

Condensation of 1-hydrazino-4-phenylphthalazine with D-arabinose, L-arabinose, D-lyxose, and D-xylose gave the corresponding 3-(tetritol-l-yl)-6-phenyl-1,2,4-triazolo[3,4-a]phthalazines (acyclic C-nucleoside analogs). D-Ribose, on the other hand, reacted with the same hydrazine to give the corresponding aldehydo-D-ribo-(4-phenyl-1-phthalazinyl) hydrazone. Catalytic dehydrogenative cyclization of this hydrazone with palladium-on-charcoal affected its transformation into the corresponding triazolophthalazine. Acetylation of the prepared acyclic C-nucleoside analogs gave the corresponding tetra-O-acetyl derivatives, the conformational analysis of which has been studied using proton magnetic resonance spectroscopy. Results of some biological activities of the prepared compounds are reported.     

Antioxidant properties of phenolic Schiff bases: structure–activity relationship and mechanism of action

Phenolic Schiff bases are known for their diverse biological activities and ability to scavenge free radicals. To elucidate (1) the structure–antioxidant activity relationship of a series of thirty synthetic derivatives of 2-methoxybezohydrazide phenolic Schiff bases and (2) to determine the major mechanism involved in free radical scavenging, we used density functional theory calculations (B3P86/6-31+(d,p)) within polarizable continuum model. The results showed the importance of the bond dissociation enthalpies (BDEs) related to the first and second (BDE_d) hydrogen atom transfer (intrinsic parameters) for rationalizing the antioxidant activity. In addition to the number of OH groups, the presence of a bromine substituent plays an interesting role in modulating the antioxidant activity. Theoretical thermodynamic and kinetic studies demonstrated that the free radical scavenging by these Schiff bases mainly proceeds through proton-coupled electron transfer rather than sequential proton loss electron transfer, the latter mechanism being only feasible at relatively high pH.     

Clavulazols A and B,Two New Pyrazine Derivatives from Clavularia Viridis

Two new marine pyrazine derivatives, clavulazols A ( 4 ) and B ( 5 ), were isolated from ethyl acetate extract of the soft coral Clavularia viridis collected in Taiwan. The structures were determined on the basis of spectral analysis, especially 2D NMR as well as chemical conversion.     

Selecting optimum maintenance strategy by fuzzy interactive linear assignment method

In the current competitive environment managers of manufacturing and service organizations try to make their organizations competitive by providing timely delivery of high quality products. Maintenance, as a system, plays a key role in reducing cost, minimizing equipment downtime, improving quality, increasing productivity and providing reliable equipment and as a result achieving organizational goals and objectives. This paper presents a new approach for selecting optimum maintenance strategy using qualitative and quantitative data through interaction with the maintenance experts. This approach has been based on linear assignment method (LAM) with some modifications to develop interactive fuzzy linear assignment method (IFLAM).     

A new effective potential for deuteron

We calculate for the first time the static properties of the deuteron, within the framework of supersymmetric quantum mechanics, analytically. A new effective potential and its partner are derived from a superpotential so that all parameters are fitted by the experimental data. An analytical expression is obtained for the deuteron wave function and contributions of the orthogonal ¹³S₁ and ¹³D₁ states are determined, explicitly. Compared to one pion exchange, the superpotential produces an electrostatic as well as two pion exchange terms for the potential. The saddle point radius of the potential and the maximum of the wave function are linearly proportional. In comparison with other methods, the approach presented in this paper is a new and extensible symmetry-based approach that, despite its straightforward calculations and explicit analytical expressions, provides a good explanation for two-body effective interactions such as two-nucleon systems and diatomic molecules.     

A comparative study between classical stirred and ultrasonically-assisted dead-end ultrafiltration

The aim of this work was to determine mass transfer coefficients in the cases of ultrasonically-assisted and classical stirred dead-end ultrafiltration. A comparative study was then performed, and mass transfer coefficients obtained under ultrasonic conditions are described by an empirical model. This correlation results from an analogy with what is observed using a stirred cell and involves the ultrasonic power as the main parameter. The hydrodynamics are assumed to depend on the intensity of the ultrasound effects illustrated by the agitation arising within the cell. This agitation is due to convective currents as well as physical effects due to cavitation. The concentration polarization phenomenon is therefore affected by this action of ultrasonic waves.