Carbohydrate-Tailored PPG#400 vs Ionic Liquid-Based Aqueous Biphasic System That Enables Extraction of Polyphenols

Polypropylene glycol (PPG#400) and an ionic liquid (IL), tris(2-hydroxyethyl)methyl ammonium methylsulfate-based aqueous biphasic system (ABS) has been constructed. The high concentration of the IL as one of the phase-forming components can make the ABS toxic and at the same time expensive. Thus, to decrease the phase-forming concentration of the IL, carbohydrates have been introduced as adjuvants. By tailoring the ABS with the help of carbohydrates, a dramatic decrease in the phase-forming concentration of IL was observed. The required concentration of the IL reduced from 80% (w/w) to ≤20% (w/w) to form an ABS with PPG#400. These observations are justified on the basis of theoretical calculations. The ABS tailored with d-mannitol as an adjuvant was chosen for further applications. The present work reports on the use of the newly designed ABS toward extraction of polyphenols such as rutin and morin. ∼75% of rutin and ∼91% of morin were extracted in the PPG#400-rich phase of ABS

Amino Acid and Block Copolymer-Based ABS: An Efficient Extraction Tool for PPIs and Consequent Recovery of the Polymer

Aiming to construct a biocompatible aqueous biphasic system (ABS), amino acids and a block copolymer, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (PPG-PEG-PPG), have been employed. Glycine and l-proline can successfully salt out PPG-PEG-PPG and can form a biphase even at room temperature, whereas l-alanine requires the temperature to be increased to at least 318 K at normal atmospheric pressure to form an ABS with the block copolymer. The phase diagrams for all the systems have been constructed using a turbidometric method at different temperatures, and the corresponding binodal graphs are plotted with the help of the Merchuk equation. An increase in temperature leads to an increase in the biphasic region. The tie line lengths, slope of the tie lines, and compositions of both the phases of the corresponding ABSs have been determined using the lever arm rule. The presence of amino acids in the place of ionic salts as one of the phase-forming components makes the ABSs eligible to extract medically relevant molecules. Herein, proton pump inhibitors (PPIs), “one of the most prescribed medicines in the world,” are extracted using the newly designed amino acid and block copolymer-based ABSs. The complete extractions of rabeprazole and pantoprazole are achieved using the glycine-based ABS, whereas ∼83% of esomeprazole is extracted with the same ABS. The extraction efficacies of the other two amino acid-based ABSs are also noticeable. After the extraction, the block copolymer-rich phase is regenerated using thermoseparation and adsorption techniques, which makes the ABS a much greener and cost-effective methodology in extraction chemistry

Comparison of Salt Cations in the Design of Nonionic Surfactant Based Aqueous Biphasic Systems: Application in Polyphenol Separations

New aqueous biphasic systems (ABSs) composed of a nonionic surfactant, Brij 35, and sulfate salts of Na, Mg, and Zn were designed. Ternary phase diagrams were constructed together with respective tie lines. The tie line lengths and slope of tie lines were calculated, and the results were validated using Othmer-Tobias and Bancroft equations. The binodals plotted for the three individual salts indicate their respective biphasic regions which follows the order MgSO₄ > ZnSO₄ > Na₂SO₄. All three ABSs were checked for their binary separation ability for the two polyphenols catechin and hesperidin. A pH dependent study indicates the possibility of separation of the two polyphenols using MgSO₄ as the salt rich phase

Biogenic Nano-CuO-Catalyzed Facile C–N Cross-Coupling Reactions: Scope and Mechanism

We demonstrate here a green and efficient biogenic synthesis of copper­(II) oxide nanoparticles using easily available <i>Ocimum Sanctum</i> leaf extract at room temperature. The biogenic copper oxide nanoparticles have shown excellent activity on N-arylation of cyclic and acyclic amides with aryl and styryl halides. Broad substrate scope, excellent functional group tolerance, and high yields were observed. This protocol is also extended for the N-arylation of substituted aryl amines and nitrogen heterocycles including pyrole, indole, imidazole, benzimidazole, and carbazole. The catalyst was characterized by EPR, UV, FT-IR, BET, AAS, TGA analysis, XPS, XRD, and HR-TEM

Sustainable Generation of Ni(OH)₂ Nanoparticles for the Green Synthesis of 5‑Substituted 1<i>H</i>‑Tetrazoles: A Competent Turn on Fluorescence Sensing of H₂O₂

A mutually correlated green protocol has been devised that originates from a sustainable production of β-Ni­(OH)₂ nanoparticles which is used for an efficient catalytic synthesis of versatile substituted tetrazoles, under mild reaction conditions in water via a simple, one-pot, eco-friendly method. The synthesis is followed by derivatization into a highly fluorescence active compound 9-(4-(5-(quinolin-2-yl)-1<i>H</i>-tetrazol-1-yl)­phenyl)-9<i>H</i>-carbazole that can be used at tracer concentrations (0.1 μM) to detect as well as quantify hydrogen peroxide down to 2 μM concentration. The nanocatalyst was synthesized by a simple, proficient, and cost-effective methodology and characterized thoroughly by UV–vis absorption and Fourier transform infrared spectra, N₂ adsorption/desorption, high resolution transmission electron microscopy, powder X-ray diffraction pattern, field emission scanning electron microscopy, and thermogravimetric analysis. Broad substrate scope, easy handling, higher efficiency, low cost, and reusability of the catalyst are some of the important features of this heterogeneous catalytic system. The strong analytical performance of the resultant derivative in low-level quantification of potentially hazardous hydrogen peroxide is the key success of the overall green synthesis procedure reported here

A phenoxo–azido assorted Schiff base copper(II) bridged dimer in trace level fluorescence sensing of a pesticide: a DFT supported phenomenon

<p>A binuclear phenoxo- and azido-bridged copper(II) Schiff base complex has been synthesized along with its mononuclear copper-Schiff base analog. The compounds have been characterized by IR spectroscopy and CHN elemental analysis. The single-crystal structure and variable temperature magnetic properties of the binuclear compound have been studied from the X-ray crystallographic data and superconducting quantum interference device magnetometry, respectively. The synthesized crystalline binuclear complex has interesting spectral features that allow it to act as a spectral sensor toward an organophosphorus pesticide which is a potential environmental toxicant coming to the environment as agricultural waste. Although both the mononuclear and binuclear complexes are suitable as sensors for the organophosphorus, the binuclear complex being crystalline is suitable for attaining structural and mechanistic details of the interaction. Density functional theory calculations and ESI MS analysis of the interactions with the binuclear complex suggest that the binding of organophosphorus substrate with <b>2</b> occurs through one copper center.</p