N‐Arylation of Heterocycles with Chloro‐ and Fluoroarenes using Resin‐Supported Sulfonato‐Cu(salen) Complex

Sulfonato‐Cu(salen) complex immobilized onto a Merrifield's resin was found to be an efficient catalyst for the N‐arylation of heterocycles with electron‐withdrawing hloro‐ and fluoroarenes. The reactions were carried out in the presence of an inexpensive mild base, K₂CO₃, and N‐arylated compounds were obtained in good to excellent yields. The catalyst was recovered by simple filtration and reused for three cycles with almost consistent activity.     

CdS quantum dots for measurement of the size-dependent optical properties of thiol capping

Abstract  

The optical- and size-dependent properties of CdS quantum dots (QDs) were analyzed in the presence and absence of different capping agents in aqueous medium. The QDs have been characterized by UV–Vis, Photoluminescence, Fourier-transform infrared spectroscopy, X-ray diffraction, and Fluorescence lifetime measurements. QDs with the presence of thiol group in cubic phase with small grain size were observed in XRD and decrease in particle size of the same with increase in band gap is deduced through UV–Vis and XRD studies. The FT-IR spectrum confirms the interaction of thiol group with CdS. Fluorescence lifetime of capped QDs was higher compared to uncapped CdS QDs. The surface passivation of thiol group on CdS is shown in photoluminescence studies.     

Schlesinger transforms for the discrete painlevé IV equation

We derive an auto-Bäcklund transformation for the discrete Painlevé IV equation and use it in order to derive Schlesinger transformations for the same equation as well as particular solutions in perfect analogy to the continuous case.     

Thermoluminescence studies of γ-irradiated nanocrystalline Y3Al5O12

Nanocrystalline yttrium aluminum garnet (Y₃Al₅O₁₂) is synthesized by combustion technique. The X-ray diffraction (XRD) pattern of 900 °C annealed sample revealed a cubic structure. The average crystallite size is found to be 20.5 nm. γ-irradiated Y₃Al₅O₁₂ exhibits two thermoluminescence (TL) glows: a prominent one with a peak at ～410 K and another one with a peak at ～575 K. It is found that the TL glow peak intensity at 410 K increases, while its glow peak temperature is almost steady with an increase in the γ-dose. The effect of the heating rate on the TL glow curve is studied. It is found that T_m1 shifts towards higher temperature region while the I_m1 decreases with an increase in the heating rate. The TL glow curves are analyzed by Chen's peak shape method and the TL parameters are estimated.     

Linearisable mappings,revisited

We examine the growth properties of second-order mappings which are integrable by linearisation and which generically exhibit a linear growth of the homogeneous degree of initial conditions. We show that for Gambier-type mappings for which the growth proceeds generically with a step of 1 there exist cases where the degree increase by unity every two steps. We examine also mappings belonging to the family known as “of third kind” in relation to the approach of Diller and Favre concerning the regularisable or not character of mappings and show that the anticonfined singularities of these mappings exhibit a linear growth with step 1. (The term anticonfined is used for singularities where the singular values extend all the way to infinity on both sides with just a few regular values in the middle). Moreover we construct specific examples of Gambier-type mappings which have anticonfined singularities and where the degree of the singularity increases linearly but where the average slope can be adjusted so as to be arbitrarily small.     

Quantum Painlevé equations: from continuous to discrete and back

We present a cascade of quantum Painlevé equations consisting in successive contiguity relations, whereupon starting form a continuous equations we obtain a discrete one, and continuous limits of the latter. We start from the quantum Painlevé V and in the process derive the quantum form of continuous PIII which was missing in previous studies.      

Comment on “painleve property of anharmonic systems with an external periodic field”

We show that the result of Steeb and Kunick concerning the singularity structure of the Van der Pol equation is false.     

Solvent-free reactions using cetyltrimethylammonium permanganate and cetyltrimethylammonium dichromate-cis-1,2-dihydroxylation of alkenes,oxidation of alcohols and regeneration of aldehydes and ketones from oximes

Cetyltrimethylammonium permanganate (CTAP) and cetyltrimethylammonium dichromate (CTAD) have been known to be good oxidizing agents in organic solvent media. This homogeneous solution phase procedure itself is a useful advantage over oxidation reactions carried out employing inorganic manganese salts (e.g., KMnO₄) or chromium salts (e.g., Kr₂Cr₂O₇) performed under heterogeneous conditions. Now we have found that oxidation reactions using CTAP or CTAD do not require a solvent medium, and can be performed under completely solvent-free conditions. We have carried out 1,2-dihydroxylation of olefins with CTAP, oxidation of alcohols to aldehydes/ketones with CTAD, and regeneration of aldehydes and ketones from their oxime derivatives using either reagent, essentially under solid phase conditions. The results are excellent. As a dihydroxylating agent the CTAP is so good that it should be able to replace the highly toxic and expensive OsO₄ for this reaction.     

Superfast Synthesis of Stabilized Silver Nanoparticles Using Aqueous Allium sativum (Garlic) Extract and Isoniazid Hydrazide Conjugates: Molecular Docking and In-Vitro Characterizations

Green synthesis of silver nanoparticles (AgNPs) was synthesized from fresh garlic extract coupled with isoniazid hydrazide (INH), a commonly used antibiotic to treat tuberculosis. A molecular docking study conducted with the selected compounds compared with anthranilate phosphoribosyltransferase (trpD) from Mycobacterium tuberculosis. The aqueous extract of garlic was prepared and mixed with silver nitrate (AgNO3) solution for the superfast synthesis of stable AgNPs. INH was then conjugated with AgNPs at different ratios (v/v) to obtain stable INH-AgNPs conjugates (AgNCs). The resulting AgNCs characterized by FTIR spectra revealed the ultrafast formation of AgNPs (<5 s) and perfectly conjugated with INH. The shifting of λmax to longer wavelength, as found from UV spectral analysis, confirmed the formation of AgNCs, among which ideal formulations (F7, F10, and F13) have been pre-selected. The zeta particle size (PS) and the zeta potential (ZP) of AgNPs were found to be 145.3 ± 2.1 nm and −33.1 mV, respectively. These data were significantly different compared to that of AgNCs (160 ± 2.7 nm and −14.4 mV for F7; 208.9 ± 2.9 nm and −19.8 mV for F10; and 281.3 ± 3.6 nm and −19.5 mV for F13), most probably due to INH conjugation. The results of XRD, SEM and EDX confirmed the formation of AgNCs. From UV spectral analysis, EE of INH as 51.6 ± 5.21, 53.6 ± 6.88, and 70.01 ± 7.11 %, for F7, F10, and F13, respectively. The stability of the three formulations was confirmed in various physiological conditions. Drug was released in a sustainable fashion. Besides, from the preferred 23 compounds, five compounds namely Sativoside R2, Degalactotigonin, Proto-desgalactotigonin, Eruboside B and Sativoside R1 showed a better docking score than trpD, and therefore may help in promoting anti-tubercular activity.     

Preparation of bio-based polymers for materials applications

A new technology developed by us for the synthesis of well defined, tailored cellulose-synthetic polymer graft polymers and crosslinked cellulose graft polymers with control over the molecular weight of the synthetic polymer graft, a high degree of graft substitution, and knowledge of the backbone-graft linkage is reviewed. The potential of bio-based polymers using these new tailored cellulosic graft polymers for use in plastics, resins, and composite applications is discussed. The new graft polymers can function as compatibilizers/interfacial agents in the preparation of biopolymer-synthetic polymer composites and blends with the desirable properties of the constitutent polymers incorporated into the new material system.