Priya Mishra

Growth mechanism and optical property of ZnO nanoparticles synthesized by sonochemical method.

ZnO nanoparticles have been synthesized by ultrasonic irradiation of an aqueous-alcoholic/aqueous-alcoholic-ethylenediamine (EDA) solutions of zinc nitrate and sodium hydroxide. ZnO nanoparticles possess hexagonal wurtzite structures and they exhibit special photoluminescence properties with a red-shift of 22 nm in UV emission band. It is found that the ultrasonic irradiation time and the solvents both influence the growth mechanism and optical properties of ZnO nanoparticles. The possible growth mechanism of ZnO nanoparticles formation by sonochemical method has been tried to discuss.

Growth mechanism and photoluminescence property of flower-like ZnO nanostructures synthesized by starch-assisted sonochemical method.

Flower-like ZnO nanostructures have been synthesized by starch-assisted sonochemical method and the effect of starch and ultrasound on the formation of ZnO nanostructure has been investigated. It is observed that starch and ultrasonic wave both plays a vital role on the growth of ZnO nanostructure. X-ray diffraction (XRD) pattern indicated that the synthesized flower-like ZnO nanostructures were hexagonal. FTIR spectrum confirms the presence of starch on the surface of flower-like ZnO nanostructure. The photoluminescence spectrum of flower-like ZnO nanostructure consists of band-edge emission at 393nm as well as emission peaks due to defects. On the basis of structural information provided by X-ray diffraction (XRD) and morphological information by Scanning Electron Microscopy (SEM), a growth mechanism is proposed for formation of flower-like ZnO nanostructures. Differential Scanning Calorimetry (DSC) of starch in liquid medium confirms that gelatinization is a two step process involving two phases.

Growth mechanism and optical property of CdS nanoparticles synthesized using amino-acid histidine as chelating agent under sonochemical process

Using amino-acid histidine as chelating agent, CdS nanoparticles have been synthesized by sonochemical method. It is found that by varying the ultrasonic irradiation time, we can tune the band gap and particle size of CdS nanoparticles. The imidazole ring of histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. The deviation in the linear relation in between cube of radius of nanoparticles and ultrasonic irradiation time confirms the growth of CdS nanoparticles occur via two process; one is the diffusion process of the reactants as well as reaction at the surface of the crystallite. CdS nanoparticles synthesized using histidine as organic chelating agent have band edge emission at approximately 481 nm and have greater photoluminescence intensity with blue-shift to higher energy due to typical quantum confinement effect.

Nucleophilic heterocyclic carbene promoted one pot multicomponent synthesis of new 6-(1H-indol-3-yl)-2-oxo-4-aryl-1,2,3,4 tetrahydropyrimidine-5-carbonitriles: an eco-compatible approach with PEG as a biodegradable medium

A three-component, one-pot, simple, direct and highly efficient cyclocondensation method has been developed for the synthesis of fourteen 6-(1H-indol-3-yl)-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidine-5-carbonitriles by combining an arylaldehyde with 3-(cyanoacetyl)-indoles and urea in the presence of the PEG-400 and a catalytic amount of the thiazolium anion. A short reaction time, simple reaction conditions, ease of product isolation, use of a cheap and readily available and reusable catalyst make this method very attractive from an environmental and economic perspective.

N-heterocyclic carbene (thiamine) promoted eco-friendly synthesis of quinoxalines under mild reaction conditions

Abstract An efficient and convenient protocol of broad scope for the synthesis of quinoxaline by cyclization-oxidation of phenacyl bromide with equimolar amount of phenylenediamine at room temperature catalyzed by thiamine in the form of N-heterocyclic carbene (NHC). High efficiency, inexpensiveness, and non-toxicity are the interesting features of the catalyst, which make it eco-friendly and highly attractive.

TUNING THE BAND GAP OF ZnO NANOPARTICLES BY ULTRASONIC IRRADIATION

In this present paper, we report the tunability of ZnO nanoparticles by ultrasonic irradiation. Different sized ZnO nanoparticles viz. 2.58–2.97 nm have been synthesized with variation of ultrasonic irradiation time 75–270 min in presence of Histidine as capping agent. UV and visible spectroscopy study revealed that as ultrasonic irradiation time increases, there is increase in amount of formed ZnO nanoparticles and also there is red shift in absorption edge. This confirms the tunability of bandgap of histidine capped ZnO nanoparticles with ultrasonic irradiation. Growth mechanism for controlling the size of ZnO nanoparticles are also discussed.

Microwave-Induced Solvent-Free Synthesis and Antifungal Screening of Novel Spiro Heterocyclic Systems Containing 3,5-Diphenyl-7H-thiazolo[3,2-a]pyrimidine and Indolin-2-one

Abstract A microwave-induced technique has been developed for the synthesis of a series of novel spiro indoline-based heterocycles (7a–g) at atmospheric pressure in an open vessel using an environmentally benign procedure. This rapid method produces pure products in good yields within a few minutes in comparison to the conventional procedure developed for the synthesis of these heterocycles. The synthesized compounds have been screened in vitro for antifungal activity against two fungal strains (i.e., Aspergillus niger and Aspergillus flavus). All compounds have shown significant activity against these pathogens. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.] GRAPHICAL ABSTRACT

Histidine functionalised biocompatible CdS quantum dots synthesised by sonochemical method

Histidine functionalised CdS quantum dots (QDs) have been synthesised by sonochemical method. Transmission Electron Microscopy (TEM) observation shows that the histidine functionalised CdS QDs are well-defined, nearly spherical particles. The X-ray diffraction pattern indicates formation of cubic phase of CdS/histidine QDs. The absorption spectra confirm quantum confinement of histidine functionalised CdS QDs. The photoluminescence property of CdS/histidine QDs is found better than that of CdS QDs. Histidine functionalised CdS QDs, in which histidine acts as a biocompatibiliser, can find potential applications in the biological fields.

Novel, versatile and eco-compatible preparation of new 6-(1 H -indol-3-yl)-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidine-5-carbonitriles in water

A three-component, one-pot, simple and direct, highly efficient cyclocondensation method has been developed for the synthesis of 11 6-(1H-indol-3-yl)-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidine-5-carbonitriles by combining an araldehyde with 3-(cyanoacetyl)-indole and urea in the presence of the cationic surfactant, CTAB and a catalytic amount of thiamine hydrochloride in water. A short reaction time, simple reaction conditions, ease of product isolation, and use of a cheap and readily available reusable catalyst make this method very attractive from an environmental and economic perspective.

ZnO nanoparticle synthesis in presence of biocompatible carbohydrate starch

ZnO nanocrystals were successfully prepared through a simple and non‐toxic route under ultrasonic irradiation using different amounts of starch. The nanocrystals were characterized by means of X‐ray diffraction (XRD), photoluminescence spectroscopy (PL) and E‐SEM (enviornmental mode). The X‐ray diffraction analysis suggested that the ZnO nanocrystals were of wurtzite structure and ESEM showed flower‐like morphology. Four different concentrations of Starch was used and pH was also varied to see the effect on optical property.