BODIPY Immobilized MCM-41 Based Multianalyte Sensor: Application in Detection and Removal of Trivalent (Al3+, Cr3+) and Divalent (Cu2+, Hg2+) Metal Ions in Aqueous Media

In the present study, a novel p-phenylcarboxylic acid BODIPY ( L ) immobilized MCM-41 based solid chemosensor material L-propylsilyl@MCM-41 ( MS4 ) was developed to detect multiple metal ions in a pure aqueous medium. The synthesized solid chemosensor material MS4 shows high sensitivity and removal ability towards trivalent (Al³⁺, Cr³⁺) and divalent (Cu²⁺, Hg²⁺) metal ions. The emission intensity of MS4 enhanced multifold selectively in the presence of trivalent (Al³⁺, Cr³⁺) metal ions and shows quenching in the presence of divalent (Cu²⁺, Hg²⁺) metal ions. The limit of detection was calculated to be in the nanomolar range with Al³⁺, Cr³⁺, Cu²⁺_, and Hg²⁺ metal ions in the aqueous medium. The spectroscopic and analytical results suggest that MS4 selectively binds with Al³⁺ and Cr³⁺ through −NH functionality and with Hg²⁺ and Cu²⁺ through −COOH functionality of p-phenylcarboxylic acid BODIPY ( L ). Further, MS4 selectively removes Al³⁺, Cr³⁺, Cu²⁺, and Hg²⁺ metal ions from the aqueous media with removal efficiency of 97.28 %, 96.34 %, 87.19 %, and 95.63 %, respectively. No noticeable change in the concentration was observed for other metal ions. The recycling potential of MS4 was evaluated using EDTA for up to seven cycles with no significant reduction in sensing capability.     

DABCO-catalyzed synthesis of 3-substituted-3-hydroxyindolin-2-ones in aqueous media

An efficient and greener protocol for easy access to 3-susbstituted-3-hydroxy-2-oxindoles by the reaction with various substituted isatins and acetophenones is described. This protocol is widely applicable for a variety of isatins and acetophenones using water as a reaction media and 1,4-diazabicyclo[2.2.2]octane (DABCO) as catalyst with shorter reaction time and good to excellent yield of products.     

Sonochemical Synthesis and Characterization of Some Alkoxyl-Functionalized Ionic Liquids Derived from 1-Butoxyl-3-butyl Imidazolium Bromide

Non-conventional techniques, such as power ultrasound (US) has been used to promote one-pot synthesis of second generation ionic liquids (ILs), reducing reaction times and improving yields. Because of the emerging importance of the ILs as green materials with wide ranging applications and our general interests in green processes such as sonication, 1-butoxyl-3-butyl imidazolium bromide (alkoxyl-functionalized) and their derivatives were synthesized using a facile and green US assisted procedure. Their structures were characterized by FT–IR, ¹H-NMR, ¹³C-NMR and mass spectroscopy.     

Levitin-Polyak Well-Posedness of Constrained Inverse Quasivariational Inequality

In this article, we introduce and study different types of Levitin–Polyak well-posedness for a constrained inverse quasivariational inequality problem. Criteria and characterizations for these types of well-posedness for inverse quasivariational inequality problems are given. Su?cient conditions for the Levitin–Polyak well-posedness of inverse quasivariational inequality problems are also established.     

Stereoselective synthesis of novel C-3 functionalized 3-sulfonyl-β-lactams: Promising biologically active heterocyclic scaffolds

An efficient and operationally simple strategy for the stereoselective synthesis of novel C-3 functionalized 3-sulfonyl-β-lactam heterocycles is described. The C-3 functionalized 3-phenyl/benzylsulfonyl-β-lactams 3/3′, 5/5′ has been synthesized via Michael addition using different Michael acceptors on trans-3-phenyl/benzylsulfonyl-β-lactams 2(a–f) using K₂CO₃ as a base and acetonitrile/DMF as solvents. The reaction furnished exclusively cis-β-lactam adducts 3(a–r) using sterically less hindered Michael acceptors. Further, the effect of steric bulk and chiralilty of Michael acceptors was explored to achieve target C-3 functionalized β-lactams 3(s-u)/3′(s-u) and 5(a–c)/5′(a–c). The structural and stereochemical analysis of novel β-lactams were carried out using FT-IR, NMR (¹H, ¹³C, ¹H-¹H COSY, ¹H-¹³C COSY and ¹³C DEPT-135), elemental analysis (CHNS), mass spectrometry (EIMS and LCMS) in representative cases and single crystal X-ray crystallographic studies (3e). The cis or trans configuration of the Michael acceptor (E) at C-3 was assigned with respect to C4-H.     

Effects of cucurbit[7]uril on enzymatic activity

The macrocyclic host cucurbit[7]uril exhibits highly specific inhibitory effects on the activity of proteases, which can be analyzed by a host-substrate complexation model.     

Monitoring stepwise proteolytic degradation of peptides by supramolecular domino tandem assays and mass spectrometry for trypsin and leucine aminopeptidase

A label-free optical detection method has been designed that allows direct monitoring of enzymatic peptide digestion in vitro. The method is based on the addition of a reporter pair, composed of the macrocyclic host cucurbit[7]uril (CB7) and the fluorescent dye acridine orange (AO), to detect the proteolytic degradation of peptides. The enzymatic activity of trypsin and leucine aminopeptidase (LAP) was investigated using H-LSRFSWGA-OH as a substrate. The substrate as well as the intermediary and final products (i.e., H-FSWGA-OH and phenylalanine) formed during its enzymatic hydrolysis differ in their binding affinity to the receptor CB7, which results in varying degrees of dye displacement and, therefore, different fluorescence intensities. CB7 showed a relatively weak binding constant of K approximately 10(4) M(-1) with the substrate, a relatively strong binding constant of K > or = 10(6) M(-1) with H-FSWGA-OH (which is a final product formed by trypsin digestion and the intermediary product formed during the enzymatic activity of LAP), and a moderate binding constant of K < or = 10(5) M(-1) with phenylalanine. Owing to this differential binding affinity of CB7 with the substrate and the corresponding products, the digestion of a peptide by trypsin was followed as a decrease in fluorescence signal, while the complete degradation of the peptide by LAP was monitored as a decrease and a subsequent increase in fluorescence signal. The k(cat)/K(M) value for trypsin (2.0 x 10(7) min(-1) M(-1)) was derived from the change in fluorescence signal with time. Additionally, the complete degradation of the peptide by LAP was also followed by mass spectrometry. The use of a supramolecular sensing ensemble (macrocyclic host and dye) as a fluorescent reporter pair gives this method the flexibility to adapt for monitoring the stepwise degradation of different biologically relevant peptides by other proteases.     

Organotin(IV) complexes of carboxylic acid derivatives

A comprehensive review, >100 references, on organotin(IV) complexes of the carboxylic acid derivatives are presented with special reference to their methods of synthesis, spectroscopic and structural studies and their biological activities. The structures of these complexes are discussed on the basis of IR, multinuclear (¹H-, ¹³C- and ¹¹⁹Sn-) NMR.     

Swift heavy ion induced effects at Mo/Si interface and silicide formation

Swift heavy ion (SHI) induced modification at metal/Si interfaces has emerged as an interesting field of research due to its large applications. In this study, we investigate SHI‐induced mixed molybdenum silicide film with ion fluences. The molybdenum thin films were deposited on silicon substrates using e‐beam evaporation at 10^?8 torr vacuum. Thin films were irradiated with Au ions of energy 120 MeV to form molybdenum silicide. The samples were characterized by grazing incidence X‐ray diffraction (GIXRD) technique for the identification of phase formation at the interface. Rutherford backscattering spectrometry (RBS) was used to investigate the elemental distribution in the films. The mixing rate calculations were made and the diffusivity values obtained lead to a transient melt phase formation at the interface according to thermal spike model. Irradiation‐induced effects at surface have been observed and roughness variations at the surface were calculated using atomic force microscopy (AFM) technique. Copyright © 2009 John Wiley & Sons, Ltd.