Chemistry

4,16-para-substituted [2,2] paracylophane with naphthalene (PCP⎼NAP), anthracene (PCP⎼ANTH), and tetraphenylethylene (PCP⎼TPE) as a new through-space conjugated dimers were prepared by the Suzuki-Miyaura cross-coupling reaction of 4, 16-diboryl [2,2] paracyclophane and respective bromo derivative using Pd(PPh3)4 as a catalyst and KOH as a base. The synthesized compounds were fully characterized by NMR, HR-MS and their photophysical, and electrochemical properties were studied. The quantum yield of PCP⎼NAP, PCP⎼ANTH and PCP-TPE were calculated and estimated as 0.21, 0.50 and 0.31 respectively. PCP⎼TPE exhibited aggregation-induced emission characteristics when the water fraction was higher than 50% in the THF/water mixtures. PCP-ANTH and PCP-TPE were also characterized by X-ray Crystallography, obtained single crystal of PCP-ANTH crystalizes in centrosymmetric monoclinic space group C2/c. A single crystal of PCP-TPE crystallizes in the centrosymmetric triclinic space group P⎼1 with one molecule residing on the inversion centre. The observed properties of these π-stacked dimers were compared through through-space Conjugation and conjugation length in the structure.

Direct Allylic Amination of Allylic Alcohols with Aromatic/Aliphatic Amines Using Pd/TPPTS as an Aqueous Phase Recyclable Catalyst. -Title reaction is highly chemoselective towards monoallylation of primary amines and proceeds for a diversity of functionalized and sterically hindered aromatic and aliphatic amines. Additionally, the reaction is atom-economical and avoids the use of a co-catalyst. The catalyst can be recycled and reused up to eight consecutive runs. -(WAGH, Y. S.; SAWANT, D. N.; DHAKE, K. P.; BHANAGE*, B. M.; Catal. Sci. Technol. 2 (2012) 4, 835-840, http://dx.doi.org/10.1039/c2cy00474g ; Dep. Chem., Inst. Chem. Technol., Univ. Mumbai, Matunga, Mumbai 400 019, India; Eng.) -Mischke 33-069

Simple methodology for the allylation of various N-and O-pronucleophiles with 1-phenyl-1-propyne as an allylating agent, using PS-TPP-Pd (polymer supported triphenylphosphine palladium) as a highly active heterogeneous recyclable catalyst has been developed. The protocol is applicable for a wide variety of hindered and functionalized aromatic amines, alcohols, and carboxylic acids. The catalyst exhibited remarkable catalytic activity for five consecutive recycles.

Development of a suitable process for the separation of trivalent lanthanides and actinides remain a challenge in large scale nuclear process. In the present work Nd(III) metal ion is chosen as a representative member of the lanthanide series and extraction behavior of Nd(III) is studied with tributyl phosphate (TBP) and an indigenously synthesized asymmetric phosphate -diethylethoxyethyl (DEEEP) in alkaline medium. The extraction method shows that Nd (III) is better extracted in alkaline medium with TBP than with DEEEP. This can be considered as an advantage for the separation of actinides from lanthanides in alkaline media.

The study of intracellular water in living cells is a challenge of fundamental importance. While the critical roles of water in maintaining and propagating life have been widely recognized and accepted, our understanding of water/biomolecule interactions is surprisingly limited. Using Raman microspectroscopic imaging of a living yeast cell followed by a multivariate analysis in form of the nonnegative matrix factorization method, we successfully resolve organelle-specific water structures. The intensities and the band profiles of the segregated water OH stretch spectra yield important and otherwise unobtainable information on the extensive effect of the water/biomolecule interactions in a given organelle on the hydrogen-bonding network of water molecules.

The study of intracellular water in living cells is a challenge of fundamental importance. While the critical roles of water in maintaining and propagating life have been widely recognized and accepted, our understanding of water/biomolecule interactions is surprisingly limited. Using Raman microspectroscopic imaging of a living yeast cell followed by a multivariate analysis in form of the nonnegative matrix factorization method, we successfully resolve organelle-specific water structures. The intensities and the band profiles of the segregated water OH stretch spectra yield important and otherwise unobtainable information on the extensive effect of the water/biomolecule interactions in a given organelle on the hydrogen-bonding network of water molecules.

The kinetics of the bimolecular Diels−Alder reaction between anthracene-9carbinol and N-ethyl maleimide have been studied in a series of pyridinium-based ionic liquids with the tetrafluoroborate ([BF 4 ] −) and the bis(trifluorosulfonimide) ([NTf 2 ] −) anions and the viscosity dependence of the rate constants have been compared with the results for the intramolecular Diels−Alder reaction of (E)-1-phenyl-4-[2-(3-methyl-2-butenyloxy)benzylidene]-5pyrazolone. The comparison leads to the surprising observation that the intermolecular reaction is less susceptible to viscosity variations of the ionic liquids as compared to the intramolecular reaction. The observed similarities and differences emphasize the complicated nature of solvent friction on the kinetics of cycloaddition reactions. The results are explained by considering the bimolecular and intramolecular processes as cases of translational and rotational diffusion, respectively. Plausible indicators of microviscosity consistent with the kinetic data for the Diels−Alder reactions are briefly discussed along with the constraints involved in designing a general microviscosity scale.

The nature and extent of preferential solvation in SNAr reaction between 1-fluoro-2,4-dinitrobenzene and morpholine are observed to depend upon the concentration of amine. Positive deviation from ideality is observed during kinetic studies of reactions carried out with lower concentration of the amine, while reaction rates measured for systems containing higher concentration of the amine show negative deviation from ideal behavior. The anomaly originates from the competition between rate-limiting proton transfer and fluoride abstraction step in the SNAr mechanism. The observations have been explained on the basis of the generally accepted mechanism and by calculation of preferential solvation parameters.

The structure and interactions of a series of ionic liquids composed of N-alkyl pyridinium cation ([C n Py] + , n = 2, 4, 6, 8, 10, 12, 14) with varied anions like bromide (Br-), tetrafluoroborate ([BF 4 ]-), bis(trifluoromethanolsulfonyl)imide ([NTf 2 ]-) and hexafluorophosphate ([PF 6 ]-) were investigated using ATR-FTIR and Raman spectroscopy. The observed frequencies were compared to the frequencies computed by means of DFT theory at the B3LYP/6-311++G(d,p) level. Significant variations were observed in the vibrational spectra of the pyridinium based ionic liquids, with increasing chain length of the alkyl group in the cation. The nature and extent of the chain-length dependent variations in the spectra was also dependent on the anionic species present in the sample. Comparison of the observed spectra to the computed spectra and previously reported data for imidazolium based ionic liquids indicate mesoscopic segregation of polar and nonpolar regions in the pyridinium ionic liquids. The strength of the cation-anion interaction determines the nature and extent of such microscopic heterogeneity, which is reflected in the anion-specific variations in the vibrational spectra. While the mesoscopic reorganization of pyridinium based ionic liquids is analogous to that in imidazolium based ionic liquids, some important differences have also been noted. The observations highlight the importance of all three structural featurescation, anion and alkyl chain lengthin determining the microscopic organization and properties of ionic liquids. The results emphasize the need for broadening the scope of ionic liquid research to include more studies on the non-imidazolium based ionic liquids.

Deep eutectic solvents have emerged as a promising and economically viable alternative to address our need for environmentally benign media. Efficient utilization of deep eutectic solvents in various fields will require adequate knowledge about their physicochemical properties. In this work, independent polarity scales pertaining to solvent polarizability, dipolarity, acidity and basicity have been determined for some commonly used deep eutectic solvents based on choline chloride. The three eutectic mixtures selected for the study include reline (1:2 mixture of choline chloride and urea), ethaline (1:2 mixture of choline chloride and ethylene glycol) and glyceline (1:2 mixture of choline chloride and glycerol). The variation of the probe response as a function of temperature revealed some interesting details about the polarity of neoteric solvents being investigated. Our observations indicate that while the polarity parameters for ethaline and glyceline are easily determined, the instability of probe molecules in reline poses a potential challenge for the determination of its polarity parameters. Attempts to correlate the empirical polarity parameters with solvatochromic response of Reichardt's dye (E T N

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Rising concern for environment hazards resulting from the use of volatile organic compounds (VOCs) is prompting many chemists to use "green" solvents like water, polyethylene glycol, ionic liquids and deep eutectic solvents (DES). With a few notable exceptions, many of these processes still need to use volatile organic solvents for the workup and isolation of products. In the present report, we demonstrate a "zero VOC" protocol which eliminates the need to use organic solvents for any stage of the reaction. As a proof of concept, nucleophilic aromatic substitution reactions of 1-halo-2,4-dinitrobenzene with secondary amines were carried out in deep eutectic solvents. The reaction workup involved the addition of water for separating the product from the DES. Evaporation of water led to recovery of the DES, which exhibited good recyclability.The reaction in deep eutectic solvents was much faster than that in many other solvents, as confirmed by the kinetic studies. An attempt was made to elucidate the origin of this rate enhancement based on analysis activation parameters and correlation with the polarity parameters. The results show that use of deep eutectic solvents can take chemists a step closer towards the "zero VOC" synthetic strategy.

Inverse gas chromatography (IGC) is an attractive technique for polymer characterization due to possible simultaneous determination of various physicochemical properties of polymer systems merely from retention times of selected sorbates. The technique is especially advantageous to polymers that cannot be characterized by conventional methods. In this review, the utilization of the method for glass transition determination of homopolymers, copolymers and polymer blends is described. Advantages and drawbacks of the IGC method over traditionally used methods for glass transition temperature determination is discussed, along with the most important parameters that influence the precision and accuracy of the glass transition temperature (T g ) measurements.

Crosslinked macroporous hydrophilic poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate)s [abbreviated poly(GMA-co-EGDMA)] with identical chemical structure (60% of glycidyl methacrylate) but with varied average pore sizes (from 30 to 560 nm), specific surface areas (from 13.2 to 106.0 m 2 /g), specific volumes (from 0.755 to 1.191 cm 3 /g) and particle sizes (less than 100-650 m) were synthesized via suspension polymerization. The influence of the resin properties on the loading of Candida antarctica lipase B (Cal-B) during immobilization and on the hydrolytic (hydrolysis of para-nitrophenyl acetate) and synthetic (ring-opening polymerization of -caprolactone) activity of the immobilized Cal-B were studied. Immobilization of Cal-B was performed at different temperatures and pH values. Cal-B immobilized at 30 • C and pH 6.8 was leading to increased activities. By decreasing the resin diameter: (i) the amount of Cal-B adsorbed onto the resin decreases, (ii) the conversion of para-nitrophenyl acetate increases (hydrolytic activity) and (iii) the conversion of -caprolactone and the molecular weight of the synthesized poly--caprolactone increases (synthetic activity). Varying the porosity parameters results in different hydrolytic and synthetic activities. Pore sizes of all synthesized resins (from 30 to 560 nm) are big enough to overcome diffusion limitations. Therefore increasing the pore size of the resins resulted in a large increase in the hydrolytic and synthetic activity. Increasing the specific surface area resulted in an increase of activities, as the result of alleviated substrate approach to the immobilized enzyme zones. The obtained results were compared to results from dried Cal-B powder and Novozyme 435. Resin with particle size less than 100 m and pore size 48 nm had much higher hydrolytic activity than both dried Cal-B powder and Novozyme 435. Nearly similar trends were observed for the synthetic activity.

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Macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), p(GME), was synthesized by suspension copolymerization and modified by reaction of the pendant epoxy groups with ethylenediamine. The sorption rate and capacity of the modified copolymer, p(GME)-en for Rh(III), Au(III) and Pt(IV) ions were determined in batch experiments under non-competitive conditions. The uptake of Rh(III) was faster than those of Au(III) and Pt(IV). The sorption capacity for Pt(IV) was determined in the pH range 0.9-6.0. The maximum Pt(IV) uptake capacity onto p(GME)-en at pH 5.5 was 1.30 mmol/g.

A series of poly(GMA-co-EGDMA) resins with identical composition but varying particle sizes, pore radii, specific surface areas and specific volumes are studied to assess how Candida antarctica lipase B immobilization affects the porosity of the copolymer particles. Mercury porosimetry reveals a significant change in the average pore size (up to 6.1-fold), the specific surface area (up to 3.2-fold) and the specific volume (up to 2.1-fold) of the epoxy resin. A similar behaviour is observed for glutaraldehyde-modified epoxy resins. The influences of the resin porosity properties on the loading of Candida antarctica lipase B during immobilization and on the hydrolytic activity (hydrolysis of p-nitrophenyl acetate) of the immobilized lipase are studied.