Preparation and photoluminescent properties of europium complexes with methoxy derivatives of 2′-hydroxy-2-phenylacetophenones

The complexes Eu(L₁)₃·2H₂O (I) [where L₁=2′-hydroxy-4′-methoxy-2-phenylacetophenone], Eu(L₂)₃·2H₂O (II) [where L₂=2′-hydroxy-4′-methoxy-2-(p-methoxyphenyl) acetophenone], Eu(L₃)₃·2H₂O (III) [where L₃=2′-hydroxy-4′, 6′-dimethoxy-2-phenylacetophenone] and Eu(L₄)₃·2H₂O (IV) [where L₄=2′-hydroxy-4′, 6′-dimethoxy -2-(p-methoxyphenyl) acetophenone] were synthesized. Energy dispersive X-ray analysis (EDX) results showed the presence of europium in all the complexes. These complexes were further characterized by infra-red spectroscopy, thermal analysis, scanning electron microscopy (scanning electron microscope) and elemental analysis. The synthesized complexes emit red luminescent with main peak at 612 nm on exposure to UV light at 354 nm. The complexes emitting bright red color might be applicable for optical devices and solid-state lamps for general illumination purposes.     

Asymptotic Behavior of Inflated Lattice Polygons

We study the inflated phase of two dimensional lattice polygons with fixed perimeter N and variable area, associating a weight exp [pA−Jb] to a polygon with area A and b bends. For convex and column-convex polygons, we calculate the average area for positive values of the pressure. For large pressures, the area has the asymptotic behaviour , where , and ρ<1. The constant K(J) is found to be the same for both types of polygons. We argue that self-avoiding polygons should exhibit the same asymptotic behavior. For self-avoiding polygons, our predictions are in good agreement with exact enumeration data for J=0 and Monte Carlo simulations for J≠0. We also study polygons where self-intersections are allowed, verifying numerically that the asymptotic behavior described above continues to hold.     

Structural Analysis of ^23O Through Single-Neutron Stripping Reaction

We have studied the single-neutron stripping reaction induced by ^23O on carbon target at beam energy of 72 MeV//A with a motive to analyze its ground state structure. The partial stripping cross sections as well as longitudinal momentum distribution of ^22O core have been calculated within the framework of the eikonal approximation approach. Several core-neutron spin coupling configurations, corresponding to J^π= 1/2 ＋ as ground state spin parity of ^23O, along with their suitable admixtures have been considered. The major outcome of the present work is that the s and d admixed configuration with a large contribution of s state seems to explain the longitudinal momentum distribution data more satisfactorily.     

Macro and microsurface morphology reconstructions during laser-induced etching of silicon

Surface morphologies of the laser-etched silicon were studied as a function of the laser power densities. Scanning electron microscope (SEM) results show that different kind of microstructures develop. Pores like structures are formed at low laser power density and pillar like structures are obtained at higher laser power density. It is the etching rate, which is responsible for the surface morphology reconstructions. Etching rate was found to be a function of the laser power density. Atomic force microscope (AFM) results reveal that macro and microsurface morphology reconstructions take place simultaneously as a result of increasing etching rate. Macrosurface morphology reconstruction takes place on the silicon wafer surface and the microsurface morphology reconstruction takes place inside the pore wall.     

Characterization of Ethylene methyl methacrylate and Ethylene butylacrylate Copolymers with Interactive Liquid Chromatography

Summary: Copolymers of ethylene with methyl methacrylate (EMMA) and butyl acrylate (EBA), which are of different average chemical composition and block lengths according to NMR analysis, were analyzed by size exclusion chromatography (SEC), differential scanning calorimetry (DSC), Crystallization Analysis Fractionation (CRYSTAF), and high performance liquid chromatography at high temperature (HT-HPLC). With CRYSTAF and DSC crystallizing fractions were detected only in some samples. HT-HPLC fractionated all the samples irrespective of their crystallinity. Homopolymers, PMMA and PE were also found in the copolymer samples of EMMA. EMMA and EBA were separated in HPLC according to the content of polar comonomer. A linear correlation between the MMA content and elution volume could not be established due to the presence of homopolymers as admixtures. In such a case the average chemical composition obtained by NMR does not correspond to the real chemical composition of the copolymers. Unlike EMMA the EBA samples eluted in single peaks, which was used for evaluation of their chemical composition distribution. The comparison of results obtained by fractionation via CRYSTAF and HT-HPLC clearly demonstrates the advantages of the chromatographic approach to study the chemical heterogeneity of olefin based copolymers.     

A Convenient One‐pot Synthesis of N‐Fused 1,2,4‐Triazoles via Oxidative Cyclization Using Trichloroisocyanuric Acid

A facile one‐pot synthesis of N‐fused 1,2,4‐triazoles from heterocyclic hydrazines and aldehydes is reported. The reaction is efficiently promoted by trichloroisocyanuric acid to afford the desired products mostly in high yields and in relatively short time. The mild nature of the synthesis and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.     

Investigation of Different Prototropic Forms of Biologically Active Flavin Lumichrome in the Presence of Liposome

Herein, we reported the photophysical behavior of lumichrome (LC), one of the biologically active flavin molecules, in the presence of small unilamellar vesicle of anionic lipid 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphocholine (DMPC). With the help of different spectroscopic techniques, we have proposed that anionic DMPC liposome interacts with the cationic form LC in ground state and in excited state and modulate the spectral properties of LC. Photophysical study reveals that different prototropic forms of LC are present in DMPC liposome medium. In the presence of DMPC liposome, fluorescence emission properties of LC vary with change in excitation and emission wavelengths. This indicates switch over between different structural forms of LC. From fluorescence lifetime measurements and fluorescence lifetime imaging (FLIM) study, it was revealed that emission decay profile of LC was fitted biexponentially in the presence of liposome. It suggests that in the presence of liposome, more than one form of LC is present. We have constructed the time‐resolved area‐normalized emission spectra (TRANES) of LC in the liposome and found one isoemissive point. This confirmed that two emissive species of LC are present in liposome. FLIM study and FE‐SEM study give an idea about the structural feature of the complex between LC and liposome.     

Growth and characterization of organic material 4-nitrobenzaldehyde single crystal using modified vertical Bridgman technique

The organic material 4-nitrobenzaldehyde single crystal has been grown using the single wall ampoule with nano-translation by modified vertical Bridgman technique. The grown crystal was confirmed by single and powder X-ray diffraction (XRD). Fourier transform infrared (FTIR) analysis was used to identify the functional groups present in the grown crystal. The optical property of the grown crystal was analyzed by UV–vis–NIR and photoluminescence (PL) spectral measurements. The thermal characteristics of the grown crystal were analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). The dielectric measurements were carried out with four different frequencies and the results indicate an increase in dielectric and conductivity parameters with the increase of temperature at all frequencies. The microhardness measurements were used to analyze the mechanical property of the grown crystal.