Stereoselective Formation of Triphenylene Ketals

The oxidative trimerization of catechol ketals by MoCl₅ or MoCl₅/TiCl₄ mixtures leads preferentially to the all‐syn stereoisomer of the corresponding triphenylene ketal. The concomitant metal salts of the oxidative coupling most probably form a multinuclear template that directs the diastereoselectivity in a subsequent isomerization step under electrophilic conditions. Several functionalities can serve as coordination sites for the multinuclear metal chloro clusters. Suitable functional groups have to be stable towards the strong electrophilic and oxidizing conditions. Therefore, esters, nitriles, nitro derivatives, triazoles, and pyridines are successfully employed. Based on the flexibility and size of the substrate, different reagent mixtures lead to the stereoselective formation of the all‐syn derivatives.     

Construction of 1,3-disubstituted 4-oxo-1,4-dihydroquinolines as a potential antibacterial agents

Research on Chemical Intermediates - A novel series of 1,3-disubstituted 4-oxo-1,4-dihydroquinolines as antimicrobial agents were designed and synthesized. Their structures have been confirmed...     

Effect of Cd content on the structural characteristic and some physical properties of Zn1−x Cd x Se

The present work focuses on the structural, optical, and electrical properties of Zn_1?x Cd _x Se (0.1≤x≤0.25) compounds. The compounds were synthesized by solid state reaction. X-ray diffraction (XRD) patterns confirm that the samples have cubic single phase (zinc-blende) crystal structure with space group F-43m. The crystal structural parameters were refined by the Rietveld method using the FullProf program. It was found that the lattice parameters increase linearly with increasing the Cd content and obeys Vegard’s law. The refined values of the crystallite size and the bond lengths increase with increasing the Cd content. The energy band gap of the samples has been calculated and it was found that it decreased as Cd increased. The conductivity of the samples increases with increasing both of composition parameter x and temperature, and showing semiconducting behavior.     

Synthesis of Novel 3-Substituted Pyridothienopyrimidine Derivatives with Biological Evaluation as Antimicrobial Agents

Novel 3-substituted pyridothienopyrimidine derivatives have been synthesized via the reaction of 2-{7,9-dimethyl-4-oxopyrido[3',2':4,5]thieno[3,2-d]pyrimidin-3(4H)-yl}acetohydrazide(5) with a variety of active reagents and chemicals. Structures of the newly synthesized compounds were established based on spectral data. The resulting pyridothienopyrimidine derivatives were evaluated for their possible antimicrobial activity and some of them represent a new class of potentially antimicrobial compounds, especially compounds 9 and 18 which displayed the highest activity against Gram-positive bacteria, Gram-negative bacteria, and Fungi in MIC range of 0.12-1.95 μg/mL.     

Synthesis of 2,2-functionalized benzo[1,3]dioxoles

Highly functionalized catechol ketals exhibiting either a tert-butyl moiety or a spiro center in position 2 are synthesized by ketalization and functionalized in a sequence of subsequent transformations. By a specific ketalization protocol catechol ketals of enolizable β-keto esters can be prepared. With the succeeding steps these compounds incorporate moieties, which are not compatible and accessible by direct ketalization of catechol.     

Electronic transport properties of low band gap a-SiGe:H alloys prepared by PECVD technique

The electronic transport properties of a-(Si,Ge):H alloys across the range of Ge content (0-40%) grown using PECVD technique have been investigated in detail by employing the microwave photomixing technique. Strong evidence for the existence of long-range potential fluctuations in a-(Si,Ge):H alloys has been found from the measurements of electric field dependence of the drift mobility. It was observed that the film transport properties degrade monotonically with increasing Ge content, where the strongest potential fluctuations occur as a result of a significant increase in the charged defect density. The potential fluctuations whose effect is enhanced by adding Ge to the alloy system result in deterioration of the transport properties of a-(Si,Ge):H alloys. Our present results demonstrate that the increased charged scattering centers and compositional disorder upon adding Ge to the alloys play an important role in the potential fluctuations.     

Discovery of Quinazoline-2,4(1H,3H)-Dione Derivatives as Potential Antibacterial Agent: Design,Synthesis, and Their Antibacterial Activity

In this paper, we report on the design and synthesis of a novel series of quinazoline-2,4(1H,3H)-dione derivatives as fluoroquinolone-like inhibitors of bacterial gyrase and DNA topoisomerase IV to identify and develop antimicrobial agents to prevent bacterial resistance problems. Their structures were confirmed using spectroscopic analyses (IR, NMR, and EI-MS). The novel quinazoline-2,4(1H,3H)-dione derivatives were evaluated for their antimicrobial activities against Gram-positive and Gram-negative bacterial strains using the Agar well diffusion method to study the antimicrobial activities and compared them with the standard drugs. Most compounds displayed moderate activity. Among the tested compounds, the most promising compounds 13 and 15 provided broad bioactive spectrum against Gram-positive and Gram-negative strains compared to the standard drugs.