Fluctuation study of pionisation in ultrarelativistic nucleus-nucleus interaction

The scaled factorial moments and the multifractal moments have been investigated in differentη-intervals to study the dynamical fluctuation of pions produced in 200 AGeV³²S-Ag/Br interaction. In order to investigate the detail characteristics of intermittency behaviour, theF-moments are extracted up to the eighth order of moments in differentM-intervals. The analysis indicates a non-thermal phase transition and different regime of particle production during the hadronisation process.     

Naphthyl-(2-pyridylmethylene)amine complexes of silver(I) and ruthenium(II): synthesis,spectral studies and electrochemical behaviour

Pyridine-2-carboxaldehyde reacts with /-naphthylamine to give /-naphthyl-(2-pyridylmethylene)amine [-L (1), -L (2)]. L belongs to the unsymmetric diimine (—N=C—C=N—) family which can form five–membered chelate rings with metal ions. {donor centers are abbreviated as N[N(Py)] and N [N(nap)]} [Ag(L)₂]⁺ complexes were prepared and characterized by spectroscopic data. The reaction between L and RuCl₃ in boiling EtOH yielded green and blue–green compounds of composition RuCl₂(L)₂. I.r., u.v.–vis. and ¹H-n.m.r. data determined the stereochemistry of the complexes as trans-cis-cis (green) and cis-trans-cis (blue–green) according to the sequence of the coordination pair of Cl, N [N(Py)] and N [N(nap)]. Upon treatment of Ag(L)₂ ⁺ with Ru(bpy)₂Cl₂ in alcoholic suspension the ternary complexes, [Ru(bpy)₂(L)](ClO₄)₂, were isolated and characterized by spectroscopic data. [Ru(bpy)(L)₂](ClO₄)₂ complexes were synthesized similarly from ctc-Ru(L)₂Cl₂ and 2,2-bipyridine (bpy) in the presence of AgNO₃ and NaClO₄. These complexes show well-defined m.l.c.t transitions in the visible region. The sterochemistry of the complexes was established by ¹H-n.m.r. data. Cyclic voltammetry shows a high potential Ru^III/Ru^II couple and follows the order: [Ru(bpy)(L)₂]²⁺ > [Ru(bpy)₂(L)]²⁺ > Ru(-L)₂Cl₂ > Ru(-L)₂Cl₂.     

A Two‐Dimensional Coordination Compound as a Zinc Ion Selective Luminescent Probe for Biological Applications

A 2D coordination compound {[Cu₂(HL)(N₃)]?ClO₄}_∞ ( 1 ; H₃L=2,6‐bis(hydroxyethyliminoethyl)‐4‐methyl phenol) was synthesized and characterized by single‐crystal X‐ray diffraction to be a polymer in the crystalline state. Each [Cu₂(HL)(N₃)]⁺ species is connected to its adjacent unit by a bridging alkoxide oxygen atom of the ligand to form a helical propagation along the crystallographic a axis. The adjacent helical frameworks are connected by a ligand alcoholic oxygen atom along the crystallographic b axis to produce pleated 2D sheets. In solution, 1 dissociates into [Cu₂(HL)₂(H₃L)]?2H₂O ( 2 ); the monomer displays high selectivity for Zn²⁺ and can be used in HEPES buffer (pH 7.4) as a zinc ion selective luminescent probe for biological application. The system shows a nearly 19‐fold Zn²⁺‐selective chelation‐enhanced fluorescence response in the working buffer. Application of 2 to cultured living cells (B16F10 mouse melanoma and A375 human melanoma) and rat hippocampal slices was also studied by fluorescence microscopy.     

Effect of adsorption of vapours on the electrical conductivity of some polyene semiconductors: adsorption and desorption kinetics

The change in semiconductive properties of β-apo-8′-carotenal, astacene and methyl bixin on adsorption of various vapours on the crystallite surfaces has been studied at a constant sample temperature. The adsorption of vapours enhances the semiconductivity of the polyenes appreciably. This enhancement depends on the chemical nature and also on the pressure of the adsorbed vapour. The adsorption and desorption kinetics follow the modified Roginsky-Zeldovich relation. A two stage desorption process, the first stage of which gives a Lennard-Jones potential energy curve and is followed by a rate-determining transition over a potential energy barrier to the second stage of adsorption forming weakly bound complexes between the vapour molecules and the polyene crystallites, can explain satisfactorily the experimentally observed kinetic data.     

Remarkably mild and efficient catalytic Sakurai reaction of N-alkoxycarbonylamino sulfones with allyltrimethylsilane using indium(III) chloride

The Sakurai reaction of N-alkoxycarbonylamino sulfones with allyltrimethylsilane in the presence of a catalytic amount of indium(III) chloride at room temperature produces the corresponding protected homoallylic amines in high yields.     

An efficient, rapid and regioselective nuclear bromination of aromatics and heteroaromatics with NBS using sulfonic-acid-functionalized silica as a heterogeneous recyclable catalyst

A simple, efficient and rapid method has been developed for high-yielding regioselective nuclear monobromination of aromatic and heteroaromatic compounds using NBS in the presence of sulfonic-acid-functionalized silica at room temperature. The catalyst works under heterogeneous conditions and can be recycled.     

A mild, rapid and highly regioselective ring-opening of epoxides and aziridines with acetic anhydride under solvent-free conditions using ammonium-12-molybdophosphate

A highly regioselective ring opening of epoxides and aziridines can be carried out efficiently with acetic anhydride to form the acetates of the corresponding 1,2-diols and 2-amino-alcohols, respectively, using ammonium-12-molybdophosphate (AMP) as a heterogeneous catalyst, at room temperature, in the absence of solvent.     

A simple, efficient and highly selective deprotection of t-butyldimethylsilyl (TBDMS) ethers using silica supported sodium hydrogen sulfate as a heterogeneous catalyst

t-Butyldimethylsilyl (TBDMS) ethers have been efficiently and selectively deprotected using silica supported sodium hydrogen sulfate (NaHSO₄·SiO₂) as a heterogeneous catalyst at room temperature to regenerate the parent alcohols in high yields.     

Perchloric Acid–Silica (HClO4⋅SiO2)‐Catalyzed Synthesis of 14‐Alkyl‐ or 14‐Aryl‐14H‐dibenzo[a,j]xanthenes and N‐[(2‐Hydroxynaphthalen‐1‐yl)methyl]amides

The synthesis of 14‐aryl‐ or 14‐alkyl‐14H‐dibenzo[a,j]xanthenes 3 involving the treatment of naphthalen‐2‐ol ( 1 ) with arenecarboxaldehydes or alkanals 2 in the presence of HClO₄?SiO₂ as a heterogeneous catalyst was achieved (Table 1), and this reaction was extended to the preparation of N‐[(2‐hydroxynaphthalen‐1‐yl)methyl]amides 5 by a three‐component reaction with urea ( 4a ) or an amide 4b – d as a third reactant (Table 2).     

Kinetics and mechanisms of the reactions of thiosulphato-amine complexes of cobalt(III). Part I. Isomerization and base hydrolysis ofcis andtrans isomers of dithiosulphatobis(ethylenediamine) cobalt(III) ion in aqueous solution

Summary Investigations were carried out on the isomerization and base hydrolysis ofcis andtrans forms of dithiosulphatobis-(ethylenediamine)cobalt(III) ions. Thecis form isomerizes to thetrans form in neutral aqueous medium, rates being 1.15, 2.30 and 4.0×10^–5s^–1, respectively at 42, 50 and 58 °C. Thetrans complex isomerizes to thecis form in basic solution only, the rate varying with pH in a sigmoid pattern. In presence of OH^–, an acid-base equilibrium of the complex ion sets in, but only the basic form takes part in the isomerization reaction. Hydrolysis of thecis isomer proceeds through a base-dependent path only, but that of thetrans isomer proceeds both through base-dependent and base-independent paths. The mechanisms are associative in nature. Thetrans form reacts faster thancis in all cases.