Molecular cable-like 1-D iodic spiral chains covered with triple helices stabilized in guest-included chiral porous framework

The supramolecular crystal {[Pr(DMFA)](3)[Ni(II)(Hbim)(3)](2)I}(n) with intricate chiral networks of [Ni(II)(Hbim)(3)](-) molecules is reported. It includes a cationic architecture as a guest, constructed from chiral nanotubes that penetrate I(-) chains with spiral channels wrapped by triple helices. The I(-) chains have AC conductivity in crystals like a molecular cable.     

Kristallstrukturen der 3 kristallinen Formen von Polyvinylidenfluorid

Ohne Zusammenfassung     

Ester-armed cyclens having quadruplicated helical geometry: remarkably stable and selective encapsulation of Na+ ion

A new series of ester-armed cyclens nicely accommodated a Na+ ion in their quadruplicated helical binding spheres and effectively discriminated the cation from Li+ and K+ ions. Crystallographic studies revealed that four ester-functionalized sidearms provided effective coordination with the Na+ ion trapped in the 12-membered cyclen ring. Log K values for their Na+ complexes were estimated as 9-11 in CD3CN or C2D5OD, which were comparable to those of common bicyclic cryptands. FAB-MS, liquid-liquid extraction, and NMR binding experiments demonstrated that the cooperative action of the parent cyclen ring and ester-functionalized sidearms offered stable and selective encapsulation of the Na+ ion based on unique quadruplicated helical geometry.     

Radical copolymerization of crotonyl compounds with styrene

The monomer reactivity ratios for the radical copolymerization of crotononitrile (CN), methyl crotonate (MC), and n-propenyl methyl ketone (PMK) with styrene (St) were measured at 60°C. in benzene and little penultimate unit effect was shown for these systems. The values obtained were: St–CN, r₁ = 24.0, r₂ = 0; St–MC, r₁ = 26.0, r₂ = 0.01; St–PMK, r₁ = 13.7, r₂ = 0.01. The rate of copolymerization and the viscosity of the copolymer decreased markedly as the molar fraction of the crotonyl compound in the monomer mixture increased. The Q–e values were also calculated to be as follows: CN, e = 1.13, Q = 0.009; MC, e = 0.36, Q = 0.015; PMK, e = 0.61, Q = 0.024. A linear relationship was obtained between the e values of the crotonyl compounds and their Hammett constants σ_m.     

One-dimensional void-space arrays constructed from a coordination polymer with bowl-like frameworks of cavitands

A one-dimensional coordination polymer of [Mn(II)(hfac)2] bridged by new bowl-like ligands of cavitands was prepared and the crystal structure was determined by X-ray crystal analysis. Ethyl acetate molecules are necessarily included as guest molecules in each of the void-space cavities of the cavitands, and then are held by weak interaction forces.     

Structure of polyethylene sulfide

The structure of the polyether series expressed by the general formula [─(CH₂)_m─O─]_n with m = 1-4, 6, 8-10, and 12 was previously determined [l]. The molecular structure of polyoxymethylene (m = 1) is a sequence of nearly gauche forms (9/5 o r 29/16 helix [a]). On the other hand, the conformation of polythiomethylene, the first member of the polythioether series [─(CH₂)_m ─S─]_n, was found to also be a nearly gauche sequence (l7/9 helix) by Carrazzolo and Valle [3]. Both of these polymers have the highest melting point of each series (polyoxymethylene, 180°C; polythiomethylene, 245°C). Polyethylene oxide (m = 2) is a 7/2 helix consisting of nearly trans, trans, and gauche forms and has rather a low melting point (66°C). Polyethylene sulfide has a very high melting point (210°C) compared with polyethylene oxide. In this respect it is thus of much interest to investigate the structure of polyethylene sulfide. Boileau et al. [4] synthesized high molecular weight polyethylene sulfide and reported its unit-cell dimensions, but they did not determine its structure. In this note, the molecular and crystal structure of polyethylene sulfide is briefly reported.