Interaction between p-tetraphenyl tetrahomodioxacalix[4]arene amide derivatives and alkali and alkaline-earth metal cations

The binding properties of four amido derivatives of p-tetraphenyl tetrahomodioxacalix[4]arene towards alkali and alkaline-earth metal cations using UV-absorption spectrophotometry, ¹H NMR and ESI-mass spectrometry techniques are reported.     

Complexation Studies of a Calix[4](aza)crown and Crystal Structure of its Magnesium Complex

A systematic study of extraction properties and complexation behaviour of the calix[4](aza)crown 1 towards alkaline earth (Mg²⁺, Ca²⁺,Sr²⁺, Ba²⁺) and transition metal (Co²⁺, Ni²⁺, Cu²⁺,Zn²⁺) cations is presented. The binding behaviour of 1 was also investigated by ¹H-NMR and the crystal structure of the 1:1 complex with Mg²⁺ isdescribed.     

Calixarene-based dendrimers. Second generation of a calix[4]-dendrimer with a ‘tren’ as core

Hyperbranched calix[4] (4) and calix[4]-dendrimer (5) as a second generation (G2) of calixdendrimers have been synthesized by divergent and convergent synthesis via amidation reactions.     

Synthese von in 2- bzw. 3-Stellung substituierten Alkandiphosphonsäuren

Synthesis of 2- or 3-substituted Alkanediphosphonic Acids Syntheses of substances of the general formula RCX(PO₃H₂)₂ X = OH, H, Cl, NH₂ have been known for a long time. The preparative possibilities for the synthesis of alkanediphosphonic acids containing an amino group or a chlorine atom in the 2- or 3-position were limited, only 2 substances from this class of compounds being known. Further examples of this class of substances have been synthesized.     

Properties of a Tetrahomodioxacalix[6]arene Derivative

The synthesis and X-ray crystalstructure of a novel tetrahomodioxacalix[6]arenehexamethylester 2 arepresented. Preliminary investigations of alkali metal ioncomplexation showed that 2 is apoor extractant with selectivity for lithium.     

Sequential photo-addition of glycine methyl-ester to [60]fullerene

While direct photo-addition of glycine-methyl-esters (GME) to [60]fullerene (C₆₀) can yield a complex product mixture, only a fulleropyrrolidine (FP) mono-adduct has been characterized and the mechanism remains to be ascertained. We show here that visible light irradiation of a mixture of C₆₀ and GME in the presence of oxygen is a direct route to synthesize sequentially higher FP poly-adducts through an unprecedented cyclization–deamination mechanism. Each step of this mechanism leads to a FP adduct involving the correlated addition of two GME radicals and the departure of an ammonia molecule.     

New determination of the fine structure constant and test of the quantum electrodynamics

We report a new measurement of the ratio h/m(Rb) between the Planck constant and the mass of (87)Rb atom. A new value of the fine structure constant is deduced, α(-1)=137.035999037(91) with a relative uncertainty of 6.6×10(-10). Using this determination, we obtain a theoretical value of the electron anomaly a(e)=0.00115965218113(84), which is in agreement with the experimental measurement of Gabrielse [a(e)=0.00115965218073(28)]. The comparison of these values provides the most stringent test of the QED. Moreover, the precision is large enough to verify for the first time the muonic and hadronic contributions to this anomaly.     

Comparaison de deux indicateurs de la régularité en variation des queues de distributionsComparison between two indicators for the variation regularity of tails of distributions

We compare assumptions used in [4] in order to study the rate of convergence to 0, as u→s₊(F), of , where $\text{F}{}_{\mathrm{u}}$ is the survival function of the excesses over u, s₊(F)=sup{x,F(x)<1} is the upper end point of the distribution function (d.f.) F and $\text{G}{}_{\mathrm{\gamma }}$ is the survival function of the Generalized Pareto Distribution, with assumptions used in [2] in order to study the rate of convergence to 0, as n→+∞, of $\text{d}\text{?}{}_{\mathrm{n}}\text{=}\text{sup}{}_{\mathrm{<mtext>x\in </mtext><mtext>R</mtext>}}\text{|F}{}^{\mathrm{n}}\text{(x)?H}{}_{\mathrm{\gamma }}\text{(}\text{x?α}{}_{\mathrm{n}}\text{σ}{}_{\mathrm{n}}\text{)|}$, where H_γ is the d.f. of an extreme value distribution. In each case, an indicator linked to regular variation assumptions had been introduced. We characterize situations where these two indicators coincide, and others where they are different. To cite this article: R. Worms, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 709–712.     

Über 1-Hydroxyalkan-1,1- diphosphonsäuren

The reaction of acylating agents with H₃PO₃ or carbonic acids with PCl₃ and calculated amounts of water gives raw products converted by steam treatment into high yields of 1-hydroxyalkane-1,1-diphosphonic acids. A cyclic condensation product of two molecules 1-hydroxyethane-1,1-diphosphonic acid was found in the raw product of the reaction of acetylating agents with H₃PO₃. Two structure proposals are discussed.