A Flexible Copper(I)‐Complexed [4]Rotaxane Containing Two Face‐to‐Face Porphyrinic Plates that Behaves as a Distensible Receptor

A new cyclic [4]rotaxane composed of two flexible bis‐macrocycles and two rigid axles is described. Each bis‐macrocycle consists of two rings attached to antipodal meso positions of a central Zn porphyrin through single C? C bonds. Each ring incorporates a 2,9‐diphenyl‐1,10‐phenanthroline chelation site. The axles contain two coplanar bidentate sites derived from the 2,2′‐bipyridine motif. The building blocks were assembled by using a one‐pot threading‐and‐stoppering reaction, which afforded the [4]rotaxane in 50 % yield. The “gathering‐and‐threading” effect of copper(I) was utilised in the formation of a [4]pseudorotaxane, which was immediately converted to the corresponding [4]rotaxane by a quadruple CuAAC stoppering reaction. The rotaxane contains two face‐to‐face zinc porphyrins, which allowed the coordination of ditopic guest substrates. The rotaxane host showed remarkable flexibility and was able to adjust its conformation to the guest size. It can be distended and accommodate rod‐like guests of 2.6 to 15.8 Å in length.     

Chiral spiro Cu(I) complexes. Supramolecular stereocontrol and isomerisation dynamics by the use of TRISPHAT anions

Association of enantiopure TRISPHAT anion (1) with chiral spiro [Cu(LL')2] complexes (LL' = 2-R-phen, 2, 6-R-bpy, 3, and 2-iminopyridine, 4) leads to an efficient NMR enantiodifferentiation. Variable temperature 1H NMR spectroscopy has been used to determine the isomerisation kinetics of these pseudo-tetrahedral complexes and to evaluate their configurational stability; the latter depending on the structure of the diimine ligands. In the case of the 2-anthracenyl-phen derivative, a decent level of supramolecular stereocontrol was noted (d.e. up to 45%); the configuration of the complex being determined by electronic circular dichroism (ECD).     

Properties of the low-lying levels in the transitional Ir and Au nuclei

We try to determine to what extent an “axial prolate rotor +1 or 2 quasiparticle model” succeeds in describing the transitional odd and odd-odd Ir and Au nuclei. The relative location of the excited states, as well as the properties of the ground and isomeric states, particularly the magnetic and spectroscopic quadrupole moments, is compared to the predictions of the model.     

Macrocycles Incorporating an Endocyclic But Non‐Sterically‐Hindering Chelate: Synthesis and Structural Studies

Two rings of different size have been prepared both incorporating a 3,3′‐biisoquinoline (biiq) chelate. The biiq ligand bears phenyl groups at its 8‐ and 8′‐positions, which provide it with an approximate crescent shape. The incorporation of the 8,8′‐diaryl‐3,3′‐biisoquinoline motif in a ring leads to an unusual situation. The complexing site of the macroring is unambiguously pointing towards the inner part of the macrocycle, but, at the same time, it is not sterically hindered, due to the relatively large distance between the coordinating site and the various organic groups belonging to the macrocyclic structure. The synthesis of the two compounds is reported, as well as the X‐ray structure of one of them, which confirms the expected geometrical properties of the molecules.     

Plasma sputtering of an alloyed target for the synthesis of Zr-based metallic glass thin films

ZrTiAlCuNi films are deposited by plasma sputtering from an alloyed target prepared by induction – cold crucible melting method. The films are found to be amorphous and exhibit a composition very similar to the target one. It is shown that the amorphous character of the deposits is rather due to the high glass forming ability (GFA) of the Zr-based alloy system, than to the deposition method used. The sputtering process of the alloyed target, composed of mixed Zr-containing phases, has been studied. It appears to be a global process leading to a quasi-congruent transfer of the target elements into the film. PACS 81.15.Cd; 61.43.Dq; 52.40.Hf     

Determination of boron by (p, a) reaction

Back-extraction of tri- and tetravalent actinides from diisodecylphosphoric acid (DIDPA) is studied using hydrazine carbonate as back-extractant. In experiments using 0.5M DIDPA–0.1M TBP n-dodecane solution, Am(III), Eu(III), Pu(IV) and Np(IV) are back-extracted, and the distribution ratios are decreased with an increase of hydrazine carbonate concentration. The back-extraction equilibria are confirmed by slope analysis in consideration of neutralization between DIDPA and hydrazine carbonate, which occurs quantitatively during back-extraction. In particular, oxidation of Np(IV) to Np(V) during back-extraction is observed by measuring absorption spectra. The hydrazinium ion acts as an oxidation reagent in the back-extraction of Np(IV). Separation factors of those metals are compared with the results of HDEHP. Hydrazine carbonate back-extracts Np(IV) more selectively from DIDPA than from HDEHP.     

Donor-acceptor molecular figures-of-eight

The intermolecular template-directed synthesis, separation and characterisation of two constitutional isomers that are self-complexing donor-acceptor [1]rotaxanes has been achieved by click chemistry, starting from a π-electron deficient tetracationic cyclophane containing two azide functions and a π-electron rich 1,5-dioxynaphthalene-containing polyether chain terminated by propargyl groups.