We observe for the first time a structural phase transition in the oxyborate Fe3O2BO3 which occurs along three leg ladders present in this material. X-ray diffraction shows that this transition at 283 K is associated with a new phase where atomic displacements occur in alternate directions perpendicular to the axis and within the plane of the ladders. Magnetic data show that these displacements lead to the formation of singlet pairs which dissociate close to the structural transition. Anomalies in the transport properties also occur close to 283 K showing that the structural transition is related to a charge ordering phenomenon in a low dimensional structure.

[reaction: see text] A new approach for the synthesis of (+/-)-indatraline, which is a 3-phenyl-1-indanamine that displays several biological activities, is described. The strategy features as the key step a diastereoselective ring contraction of a 1,2-dihydronaphthalene promoted by PhI(OTs)OH, to construct the indan ring system. The oxidative rearrangement of other 1,2-dihydronaphthalenes was also investigated, generalizing this method to obtain indans.

The alpha zein, the maize storage prolamin, is a mixture of several homologous polypeptides that shows two bands in SDS-PAGE, called Z19 and Z22. The conformation studies carried out by several authors in this mixture are conflicting. To elucidate these inconsistencies, we analyzed the conformation of the Z19 fraction, extracted from BR451 maize variety by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and small-angle X-ray scattering. The infrared results show that Z19 has 46% of alpha helix and 22% of beta sheet. The fast N-H to N-D exchange measured by (1)H NMR spectroscopy showed that Z19 is not a compact structure. The scattering measurements indicated an extended structure with 12 by 130 A. With these data, we have modeled the Z19 structure as a hairpin, composed of helical, sheet, turns, and secondary structures, folded back on itself.