Bingel–Hirsch Addition of Diethyl Bromomalonate to Ion-Encapsulated Fullerenes M@C60 (M=Ø, Li+, Na+, K+, Mg2+, Ca2+, and Cl−)

In the last 30 years, fullerene-based materials have become popular building blocks for devices with a broad range of applications. Among fullerene derivatives, endohedral metallofullerenes (EMFs, M@C_x) have been widely studied owing to their unique properties and reactivity. For real applications, fullerenes and EMFs must be exohedrally functionalized. It has been shown that encapsulated metal cations facilitate the Diels–Alder reaction in fullerenes. Herein, the Bingel–Hirsch (BH) addition of ethyl bromomalonate over a series of ion-encapsulated M@C₆₀ (M=Ø, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, and Cl⁻; Ø@C₆₀ stands for C₆₀ without any endohedral metal) is quantum mechanically explored to analyze the effect of these ions on the BH addition. The results show that the incarcerated ion has a very important effect on the kinetics and thermodynamics of this reaction. Among the systems studied, K⁺@C₆₀ is the one that leads to the fastest BH reaction, whereas the slowest reaction is given by Cl⁻@C₆₀.     

Synthesis,spectral characterization,thermal study and antimicrobial activity of (E)-4-(substituted 1-Benzo[d]imidazole-2-yl)-N'-(substituted Benzylidene)benzohydrazide schiff bases

Antimicrobial properties casing wide applicability in water detoxification, pharmaceutics and in industries. Present work focus on the synthesis of a new series of Schiff Bases (E)-4-(1 substituted-1H Benzo[d]imidazole-2-yl)-N'-(substituted Benzylidene)benzohydrazide (5a-5l) were synthesized. The convenient route for the synthesis of new analogues by the condensation of 4-(substituted -1H-Benzo[d]imidazole-2-yl)-N'- Hydrazine with different derivatives of aromatic aldehydes were described using different solvents and catalysts. The structures of the synthesized compounds were ascertain by spectral techniques viz. IR, ¹H NMR, MS and Physical Elemental data. Compounds were also subjected to thermal analysis to study their physical and chemical properties. The title compounds were also screened for their antimicrobial activity against various bacterial & Fungal strains. Results of bioassay vary with diverse group attached to Benzimdazole motif and could be helpful for the development of other bioactive molecules.     

Polyelectrolyte properties of a plant and animal polysaccharide

The principal properties of polyelectrolytes in aqueous solution are reviewed; experimental data obtained about polysaccharides in our laboratory identify the main electrostatic interactions which occur between macromolecular chains, between ionic sites on isolated chains or between counterions and polyelectrolytes. Two examples are described. Hyaluronan, a linear alternated copolymer type with one anionic site per repeat unit, is very soluble in water, with a persistence length around 8 nm and a rheological behavior directly related to the molecular weight and polymer concentration in the presence of external monovalent electrolyte. The second example is that of pectin for which the influence of the charge density is studied. It exhibits an important ionic selectivity among divalent counterions in dilute solution with a dimer formation followed by aggregation and gelation.     

Nickel Pyrazolyl Borate Complex: Synthesis,Structure, and Analytical Application as Benzoate Selective Sensor

The complex [Tp^Ph,MeNi(Cl)Pz^Ph,MeH] ( I ) [Tp^Ph,Me=hydrotris(3‐phenyl‐5‐methyl‐pyrazol‐1‐yl)borate; Pz^Ph,MeH=3‐phenyl‐5‐methyl‐pyrazole] has been synthesized and explored as ionophore for the preparation of a poly(vinyl chloride) (PVC) membrane sensor for benzoate anions. The formation constants for the interaction of complex I with different organic/inorganic anions in solution have also been studied by sandwich membrane method. PVC based membranes of I using tridodecylmethylammonium chloride (TDDMACl) as cation discriminator and o‐nitrophenyloctyl ether (o‐NPOE), dibutylphthalate (DBP), benzylacetate (BA) and tributylphosphate (TBP) as plasticizing solvent mediators were prepared and investigated as benzoate selective sensors. The best performance was shown by the membrane with composition (w/w) of I (5): PVC (150): NPOE (345): TDDMACl (0.3). The proposed sensor exhibits significantly enhanced selectivity toward benzoate ions over the concentration range 2.2×10^?6–1.0×10^?1 M with a lower detection limit of 1.4×10^?6 M and a Nernstian slope of 59.2 mVdecade^?1 of activity within a pH range of 4.5–8.5. The sensor has a response time of 12 s and can be used for at least 8 weeks without any considerable divergence in their potential response. The membrane sensor of complex I have been checked for reversible and accurate sensing of benzoate levels present in liquid food products.     

Electrochemical Studies of the Benzoate Adsorption on Au (111) Electrode

Cyclic voltammetry (CV), differential capacity (DC), and charge densitymeasurements have been employed to study the benzoate (BZ) adsorption at the Au(111)electrode surface. Thermodynamic analysis of charge density (_M) data has beenperformed to describe the properties of the adsorbed benzoate ion. The Gibbsexcess , Gibbs energy of adsorption G, and the number of electrons flowingto the interface per adsorbed benzoate ion at a constant potential (electrosorptionvalency) and at a constant bulk concentration of the benzoate (reciprocal of theEsin—Markov coefficient) have been determined. The results demonstrate thatalthough benzoate adsorption starts at negative charge densities, it takes placepredominantly at a positively charged surface. At the most positive potentials,the surface concentration of benzoate attains a limiting value of about 7.3×10^–10mol-cm^–2, which is independent of the bulk benzoate concentration. This valueis consistent with packing density corresponding to a closed-packed monolayerof vertically adsorbed benzoate molecules. At negative charge densities, benzoateassumes a flat (-bonded) surface coordination. The surface coordination ofbenzoate changes, by moving from a negatively to positively charged surface.At the negatively charged surface, the electrosorption bond is quite polar. Thepolarity of the chemisorption bond is significantly reduced due either to a chargetransfer or a screening of the charge on the anion by the charge on the metal.     

Two New Benzoate‐di(methylcyclopentadienyl)ytterbium(III) Complexes: [Yb(MeCp)2(O2CC6F5)]2 and [Yb(MeCp)2(O2C‐o‐HC6F4)]2

Transparent orange crystals of [Yb(MeCp)₂(O₂CC₆F₅)]₂ and [Yb(MeCp)₂(O₂C‐o‐HC₆F₄)]₂ were obtained by oxidation of Yb(MeCp)₂ with M(O₂CR) (M = ¹/₂ Hg, Tl; R = C₆F₅, o‐HC₆F₄) in tetrahydrofuran. They have a dimeric structure with bridging bidentate (O, O')‐benzoate groups and eight coordinated ytterbium. Both crystallise isotypic in the orthorhombic space group Pbca. Room temperature as well as low temperature single crystal X‐ray investigations show the o‐H/F positions in [Yb(MeCp)₂(O₂C‐o‐HC₆F₄)]₂ not to be ordered.     

纸色谱法快速分离液相色谱法测定食品中苯甲酸钠和山梨酸钾

提出以纸色谱法对食品中的苯甲酸钠和山梨酸钾进行分离，以液相色谱定性、定量其结果。方法简便、快速、准确。     

Counterion binding to poly(allylammonium) cation

Chloride ion activity coefficients in aqueous solutions of poly(allylamine) hydrochloride (PAA · HCl) have been determined both in the absence and the presence of simple salts. Without added salt, the activity coefficient depends on the polymer concentration. With added salt, the binding of added counterions by PAAH⁺ is evaluated from the release of chloride ion. The extent of interaction between counterions and PAAH⁺ at a given polymer concentration decreases in the order SO ? ClO > NO > Cl^? > Br^? > I^?. This order of counterion selectivity agrees with the previous estimation of potentiometric titrations. The result shows that the hydration of the counterion, as well as its charge, plays an important part in counterion binding to the polyion.     

Inverse phase transfer catalysis: kinetics of the pyridine-1-oxide-catalyzed two-phase reactions of methyl-, methoxy-, iodo-, and nitro-benzoyl chlorides and benzoate ions

The substitution reactions of XC₆H₄COCl [X=2-, 3-, or 4-CH₃; 2-, 3-, or 4-CH₃O; 2-, or 4-I; or 2-, 3-, or 4-NO₂] and YC₆H₄COONa [Y=2-, 3-, or 4-CH₃; 2-, 3-, or 4-CH₃O; 2-I; 4-NO₂; or H] in a two-phase H₂O/CH₂Cl₂ medium using pyridine-1-oxide (PNO) as an inverse phase transfer catalyst were investigated. In general, the kinetics of the reaction follows a pseudo-first-order rate law, with the observed rate constant being a linear function of the concentration of PNO in the water phase. In contrast to other analogous reactions, the hydrolysis reaction of 2-, 3-, or 4-NO₂C₆H₄COCl in H₂O/CH₂Cl₂ medium is catalyzed considerably by PNO and reaches an equilibrium. In the PNO-catalyzed reaction of XC₆H₄COCl and XC₆H₄COONa in H₂O/CH₂Cl₂ medium, the order of reactivities of XC₆H₄COCl toward reaction with PNO in CH₂Cl₂ is 2-IC₆H₄COCl>4-IC₆H₄COCl>(C₆H₅COCl,3-CH₃OC₆H₄COCl)>3-CH₃C₆H₄COCl>(2-CH₃C₆H₄COCl,4-CH₃C₆H₄COCl)>4-CH₃OC₆H₄COCl>2-CH₃OC₆H₄COCl. Combined with the results of other analogous reactions, good Hammett correlations with positive reaction constant were obtained for the meta- and para-substituents, which supports that the XC₆H₄COCl–PNO reaction in CH₂Cl₂ is a nucleophilic substitution reaction.