Electrophilic aryl-halogenation using N-halosuccinimides under ball-milling

We report here a methodology of chemo- and regio-selective aryl bromination and iodination using respective N-halosuccinimides at room temperature in the absence of any solvents, catalyst/additives under ball-milling condition. However, for chlorination ceric ammonium nitrate was used as additive. The coupled product succinimide, produced from the reactions, was recycled via regeneration of NBS. This methodology works with the electron-donor substituted or unsubstituted arenes.     

Treatment of sugar processing industry wastewater using copper electrode by electrocoagulation: Performance and economic study

This paper demonstrates the use of copper electrode for the treatment of sugar processing industry wastewater (SPIW) in terms of chemical oxygen demand (COD) by applying electrocoagulation (EC) method. EC process was carried out in batch mode with electrode effective area of 0.0112 m², supplied current intensity (CI) of 44.64 A/m² - 223.21 A/m², electrode gap (EG) of 0.5–2.5 cm, electrolyte (NaCl) dose (ED) of 0.5–2.5 g/L to treat SPIW with initial chemical oxygen demand (COD) of 6000 mg/L. The maximum COD removal 73% of SPIW is achieved at optimized condition of SPIW pH: 7, CI: 89.28 A/m², EG: 1.5 cm & ED: 1.5 g/L. Sludge and scum generated during EC process were characterized by FTIR, TGA/DTA/DTG, proximate & ultimate analysis to find its applicability and their disposal. Additionally, economic study of EC treatment process at optimum condition suggest treatment cost was 11.2 US$/m³ and it indicate economic results as comparison to other available treatment processes.     

A Comparative Study of the Nonlinear Optical Properties of Cd<Subscript>n</Subscript>X<Subscript>n</Subscript> (X: S,Se and Te) Clusters

We report results of hyperpolarizability calculations on Cd_nX_n (X: S, Se and Te; n = 1–10) clusters. Our results show that the geometric configurations of different types of clusters under investigation are quite similar at specific values of n. Both static and frequency dependent components of first and second order hyperpolarizability tensors of Cd_nS_n, Cd_nSe_n and Cd_nTe_n are compared. It is observed that in general nonlinear optical coefficients show identical variation in all the cluster materials. The present investigation also manifests the improvement of these coefficients due to the introduction of asymptotically correct generalized gradient approximation functional over the local density functional and normal gradient corrected functional. Symmetrized fragment orbital analysis has been performed to provide explanation of the observed hyperpolarizability variation. We also analyse how geometries with closely lying energy values influence the hyperpolarizabilities of these cluster materials.     

Role of positional isomers on receptor-anion binding and evidence for resonance energy transfer

New urea-based sensors show a strong affinity for F⁻, CH₃COO⁻, and H₂PO₄⁻ with an appreciable color change in the presence of excess F⁻. The position of the nitro group in the urea derivative influences the relative affinity toward anionic analytes. Spectral and ab initio studies showed the difference in the deprotonation sites for the ortho- and meta/para-isomers in these cases. Photophysical studies confirmed the resonance energy transfer in the case of the ortho-isomer. The ortho-isomer can act as a dual emission probe for F⁻.     

Structure of marsileagenin a; A new hexahydroxy triterpene from marsilea minuta linn

The crude saponin obtainable from Marsilea minuta Linn on acid hydrolysis yielded a mixture of sapogenols. The major sapogenol named Marsileagenin A was found to be a hexahydroxy triterpene of oleanene series. From a study of various spectrometric data together with chemical reactions the structure of this sapogenol has been assigned as olean-12-ene-2α, 3β, 16β, 21β, 22α, 28-hexol (1a).     

Mixed equilibrium problems with relaxed \alpha -monotone mapping in Banach spaces

Using the KKM mapping technique, we obtain existence results for the mixed equilibrium problem (under the relaxed \(\alpha \)-monotonicity assumption on the bi-function) in a reflexive Banach space. Several examples are given to show that our definition of \(\alpha \)-monotonicity and, hence, our results are more general than that in the existing literature.     

Solvent‐Free Ball‐Milling Subcomponent Synthesis of Metallosupramolecular Complexes

Subcomponent self‐assembly from components A , B , C , D , and Fe²⁺ under solvent‐free conditions by self‐sorting leads to the construction of three structurally different metallosupramolecular iron(II) complexes. Under carefully selected ball‐milling conditions, tetranuclear [Fe₄( AD ₂)₆]^4? 22‐component cage 1 , dinuclear [Fe₂( BD ₂)₃]^2? 11‐component helicate 2 , and 5‐component mononuclear [Fe( CD ₃)]²⁺ complex 3 were prepared simultaneously in a one‐pot reaction from 38 components. Through subcomponent substitution reaction by adding subcomponent B , the [Fe₄( AD ₂)₆]^4? cage converts quantitatively to the [Fe₂( BD ₂)₃]^2? helicate, which, in turn, upon addition of subcomponent C , transforms to [Fe( CD ₃)]²⁺, following the hierarchical preference based on the thermodynamic stability of the complexes.     

Impact of Metal Ions in Porphyrin‐Based Applied Materials for Visible‐Light Photocatalysis: Key Information from Ultrafast Electronic Spectroscopy

Protoporphyrin IX‐zinc oxide (PP‐ZnO) nanohybrids have been synthesized for applications in photocatalytic devices. High‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction (XRD), and steady‐state infrared, absorption, and emission spectroscopies have been used to analyze the structural details and optical properties of these nanohybrids. Time‐resolved fluorescence and transient absorption techniques have been applied to study the ultrafast dynamic events that are key to photocatalytic activities. The photocatalytic efficiency under visible‐light irradiation in the presence of naturally abundant iron(III) and copper(II) ions has been found to be significantly retarded in the former case, but enhanced in the latter case. More importantly, femtosecond (fs) transient absorption data have clearly demonstrated that the residence of photoexcited electrons from the sensitizer PP in the centrally located iron moiety hinders ground‐state bleach recovery of the sensitizer, affecting the overall photocatalytic rate of the nanohybrid. The presence of copper(II) ions, on the other hand, offers additional stability against photobleaching and eventually enhances the efficiency of photocatalysis. In addition, we have also explored the role of UV light in the efficiency of photocatalysis and have rationalized our observations from femtosecond‐ to picosecond‐resolved studies.