Benzohydroxamic acid as a reductometric titrant: Determination of manganese, chromium and vanadium in steels

A method has been developed for the rapid determination of manganese and chromium by direct stepwise reductometric titration with benzohydroxamic acid, and of vanadium by titration with ascorbic acid (with benzohydroxamic acid as indicator) in the same aliquot. The method is free from the interference of common alloying elements present in steels. Some BCS steel samples have been analysed with good precision and accuracy.     

Organic reactions in a solid matrix-vi: Silica-gel supported reagents for the isolation of aldehydes and ketones

Semicarbazide-on silica gel and Girard-T-on-silica gel are described and evaluated as convenient reagents for efficient isolation of aldehydes and ketones from mixtures with other usual neutral organic components Semicarbazide-on-silica gel, which can be readily prepared, can effectively replace the classical Girard reagents, for the isolation of aldehydes and ketones in most cases.     

Analysis of the effect of the temperature variation on transistor parameters and gain

The variations of the hybridh-parameters and the gain of the transistor with temperature have been studied by obtaining an analytical expression. The values of theh-parameters are calculated in the entire temperature range 213–473 K with the help of the expression obtained and the calculated values are in good agreement with the experimental data. The gain of the transistor extracted from the obtained values of the parameters is seen to be in excellent agreement with the experimental values.

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Zusammenfassung Die Änderung des Hybrid-Parameters und die Verstärkung des Transistors mit der Temperatur wurden untersucht, indem ein analytischer Ausdruck hierfür erhalten worden ist. Die Werte derh-Parameter wurden im ganzen Temperaturbereich von 213 bis 473 K mit Hilfe des erhaltenen Ausdrucks berechnet und die berechneten Angaben sind in guter Übereinstimmung mit den Versuchsergebnissen. Die aus den erhaltenen Parameterwerten errechnete Transistorverstärkung stimmt mit den Versuchswerten sehr gut überein.

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Résumé On a étudié, à l'aide d'une expression analytique obtenue pour le but poursuivi, la variation des paramètresh hybrides et l'amplification du transistor avec la température. On a calculé, à l'aide de cette expression, les paramètresh dans tout l'intervalle des températures comprises entre 213 et 473 K. Les valeurs calculées sont en bon accord avec les données d'expériences. L'amplification du transistor, calculée à partir des valeurs obtenues, est en excellent accord avec les valeurs d'expériences.

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h- . h 213–473 . , , , .

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Ex-student (M.Sc.) of Department of Physica, R.E.C. Waranga-506004, India.

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The work was done in the Department of Physica, R.E.C. Warangal-506004, India.

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The authors wish to express their thanks to Dr. V. V. Rao and Dr. G. S. Verma for their interest in the present project. One of us (K.S.D.) is also grateful to Dr. R. A. Rashid and Dr. R. H. Misho.     

Self-assembly of C(3)(h) and C(s) symmetric keto-enamine forms of tris(N-salicyl-ideneanilines) into columnar phases: a new family of discotic liquid crystals

A new class of discotic liquid crystals derived from tris(N-salicylideneanilines) existing exclusively in their C3h and Cs keto-enamine tautomeric forms is reported. These compounds self-assemble to form columnar liquid crystalline phases with a small core-core separation as evidenced by X-ray diffraction studies.     

Increased carrier mobility in end-functionalized oligosilanes

We show that a class of oligosilane–arene σ, π-hybrid materials exhibits distinct and enhanced solid-state electronic properties relative to its parent components. In the single crystal structure, the σ-conjugation axis of one molecule points towards the π-face of a neighboring molecule due to an unusual gauche conformation. This organization is hypothesized to be beneficial for charge transport. We show that solution-deposited crystalline films of the hybrid materials show up to a 100-fold increase in space-charge limited current (SCLC) mobility relative to literature reports of photoinduced hole transport in oligosilane films. The discovery that σ, π-hybrids are more than the sum of their parts offers a design opportunity for new materials.     

In silico identification and in vitro antiviral validation of potential inhibitors against Chikungunya virus

Journal of Computer-Aided Molecular Design - The Chikungunya virus (CHIKV) has become endemic in the Africa, Asia and Indian subcontinent, with its continuous re-emergence causing a significant...     

Nano CuO–Ag-catalyzed synthesis of some novel pyrano[2,3-d] pyrimidine derivatives and evaluation of their bioactivity

A simple, highly efficient, and green method is developed for the synthesis of pyrano[2,3-d] pyrimidine derivatives via Knoevenagel and Michael addition in the presence of nano CuO–Ag as a catalyst. The structures of synthesized target compounds 5a–l were confirmed by spectral and elemental analysis and were screened for their antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH), H₂O₂, and NO methods. Their antibacterial activity against Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli, against Gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus, and antifungal activity against Candida albicans and Candida glabrata was also evaluated. The compounds showed higher bacterial activity than the standard used. Compounds 5b , 5d , 5g , 5h , and 5i exhibited higher free radical scavenging activity than the standard butylated hydroxy toluene (BHT). Compounds 5b , 5d , and 5h showed higher activity on Gram-positive bacteria, and compounds 5b , 5d , 5h , and 5i showed higher activity on Gram-negative bacteria than that of standard tetracycline. Compounds 5b , 5j , and 5l showed much higher antifungal activity against Candida globrata and C. albicans than that of standard Griseofulvin.     

Photoinduced Charge Separation in Molecular Silicon

Interest in molecular silicon semiconductors arises from the properties shared with bulk silicon like earth abundance and the unique architectures accessible from a structure distinctly different than rigid π‐conjugated organic semiconductors. We report ultrafast spectroscopic evidence for direct, photoinduced charge separation in molecular silicon semiconductors that supports the viability of molecular silicon as donor materials in optoelectronic devices. The materials in this study are σ–π hybrids, in which electron‐deficient aromatic acceptors flank a σ‐conjugated silicon chain. Transient absorption and femtosecond‐stimulated Raman spectroscopy (FSRS) techniques revealed signatures consistent with direct, optical charge transfer from the silane chain to the acceptor; these signatures were only observed by probing excited‐state structure. Our findings suggest new opportunities for controlling charge separation in molecular electronics.     

The structure of cis and trans lsomers of 1-(p-Bromobenzylidene)-2-indanone

Abstract

In this communication we wish to report an interesting case of the isolation and characterization of the cis and trans isomers of 1-(p-bromobenzylidene)-2-indanone and their ketals. Prior to this work, Hoogstreen and Trenner² had reported on the cis and trans isomers of 1-(p-chlorobenzylidene)-2-methyl-5-methoxyindenylacetic acid. The condensation of 2-(N-morpholinyl)-indene (1, prepared by the reaction of 2-indanone³ and morpholine) with P-bromobenzaldehyde was conducted by refluxing them in the presence of acetic acid for 4 hours. Acid hydrolysis of the reaction mixture followed by dry column chrcmatography over sillica gel using a fraction collector afforded two iscmeric monobenzylidenes, compounds 2(36.6%, mp 110–111°)and 3(1.3%, mp 115–116°) and a dibenylidene, compound 4 (8.7%, mp 205°). The relative rations of the mono- and dibenzylidenes seemed to depend on the reaction conditions. Higher yields of the monobenzylidenes 2 and 3 were obtained by conducting the reaction in the presence of UV light. The structures of these monobenzylidenes were established as cis and trans isomers of 1-(p-bromobenzylidenes)-2-indanone on the Basis of elemental analyses and ir and nmr spectroscopy. The ir spectra⁴ (CHCl₃)

of compounds 2 [1725 (c=0), 1620 (c=c)cm^?1] and 3[1710 (c=o), 1570, 1600 (c=c) cm^?1] were consistent with the structures. The molecular ion peaks as well as the fragmentation patterns in the mass spectra of both these compounds were consistent with the assigned structures. Before going into the omr discussion it should be pointed out that treatment of compound 2 with athylene glycol in the presence of p-toluene sulfonic acid produced two ketals, 5 (38.3% mp, 118–120°) and 6 (30.6% mp, 125–126°). As depicted; the ketals 5and 6 were also found (by omr) to be related to each other as cis and trans isomers. Furthermore, each of them could be hydrolyzed with acid to the corresponding monobenzylidenes 2 and 3 without any isomerization. However, UV irradiation of compounds 2 and 3 gave equilibrium mixtures containing both the isomers, indicating isomerization had occurred under photolytic conditions.     

Photoreduction of an α-Dichloroketone

We describe here a simple three step synthesis of B-santalene (1), one of the main hydrocarbons in East Indian Sandalwood oil,³ using the readily available camphene sultone (2) as a starting material. This synthesis, outlined in Figure 1, features the novel use of a sultone as a carbon activating group and involves a new desulfurization procechrre.