Errors in the elemental analysis results in the paper by Liu et al. [ Acta Cryst. (2013), C 69 , 1488–1493] are corrected.
First-principles calculations show that strain-induced topological phase transition is auniversalphenomenon in those narrow-gap semiconductors for which the valence band maximum (VBM) and conduction band minimum (CBM) have different parities. The transition originates from the opposite responses of the VBM and CBM, whose magnitudes depend critically on the direction of the applied strain. Our work suggests that strain can play a unique role in tuning the electronic properties of topological insulators for device applications, as well as in the achievement of new topological insulators.
The molecules in (E)-N-(3,4,5-trimethoxybenzylidene)naphthalen-1-amine, C20H19NO3, (I), and its reduction product N-(3,4,5-trimethoxybenzyl)naphthalen-1-amine, C20H21NO3, (II), are both conformationally chiral, but (I) crystallizes in a centrosymmetric space group, while (II) crystallizes with just one conformational enantiomer in each crystal. A combination of two C-H···O hydrogen bonds links the molecules of (I) into sheets containing a single type of R(6)(6)(44) ring, and these sheets are linked into a continuous three-dimensional array by a single π-π stacking interaction. The molecules of (II) are linked into complex sheets by a combination of N-H···O, C-H···O and C-H···π(arene) hydrogen bonds.
A new inorganic-organic hybrid zinc phosphite, [Zn(HPO3)(C6H11NO2)](n), has been synthesized hydrothermally. Protonated piperidin-1-ium-4-carboxylate (PDCA) was generated in situ by hydrolysis of the piperidine-4-carboxamide precursor. The P atom possesses a typical PO3H pseudo-pyramidal geometry. The crystal structure features an unusual (3,4)-connected two-dimensional inorganic zinc-phosphite layer, with organic PDCA ligands appended to the sheets and protruding into the interlayer region. Helical chains of opposite chirality are involved in the construction of a puckered sheet structure.
