The E and Z isomers of 3‐(benzoxazol‐2‐yl)­prop‐2‐enoic acid

The carboxyl­ic acid group and the double bond are coplanar in (E)‐3‐(benzoxazol‐2‐yl)­prop‐2‐enoic acid, C₁₀H₇NO₃, whereas in isomeric (Z)‐3‐(benzoxazol‐2‐yl)­prop‐2‐enoic acid, also C₁₀H₇NO₃, they are almost orthogonal. In both isomers, a strong O—H⋯N hydrogen bond, with the carboxyl­ic acid group as a donor and the pyridine‐like N atom as an acceptor, and weak C—H⋯O interactions contribute to the observed supramolecular structures, which are completed by π–π stacking interactions between oxazole and benzenoid rings.     

One and Two-Dimensional 1,4-Xylylenediammonium (pXDA) Lead Halides: Powders and Thin Films

The discovery of new 3D perovskites and their 2D and 1D analogues continues to attract the interest of the scientific community and therefore the understanding of their structural, optical, and physicochemical properties is of fundamental importance. Here, we report the one-pot synthesis and the full characterization of 1D and 2D lead halide polycrystalline solids containing the rather rigid 1,4-xylylenediammonium (pXDA) organic cation as spacer. We isolated 2D Dion-Jacobson (DJ) perovskites, namely (pXDA)PbX₄ (X=Cl, Br) and the mixed halide (pXDA)Pb(Br_1–xI_x)₄ species (all based on 2D monolayers of corner-sharing lead halide octahedra), and, for iodine, the (pXDA)Pb₂I₆ . 2H₂O phase, which contains 1D ribbons. The latter species can be reversibly dehydrated by gentle heating, forming the isomorphous (pXDA)Pb₂I₆. crystal phase. These species, some of which have recently been studied in the frame of broad light emitters and for photovoltaic applications, have been characterized by variable-temperature X-ray diffraction methods, shedding light onto their anisotropic thermal responses, of utmost importance for day-night cycling in functional devices. Spin-coated thin films were also prepared and studied by means of synchrotron radiation grazing incidence X-ray diffraction, SEM imaging and fluorescence spectroscopy experiments.     

Diorganotin(IV) compounds derived from n‐methyl‐2,2′‐diphenolamine and 2,2′‐diphenolamine

The reaction of N‐methyl‐2,2′‐diphenolamine 1 and 2,2′‐diphenolamine 2 with some diorganotin(IV) oxides [R1/2SnO: R¹ = Me, n‐Bu, t‐Bu and Ph] led to the syntheses of diorgano[N‐methyl‐2,2′‐diphenolato‐O,O′,N]tin (IV) 3–6 and diorgano[2,2′‐diphenolato‐O,O′,N]tin (IV) 7–9 . All compounds (except 7 ) studied in this work were characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, infrared, and mass spectroscopy. Their ¹¹⁹Sn NMR data show that the tin atom is tetracoordinated in CDCl₃ but penta and hexacoordinated in DMSO‐d₆. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 133–139, 1999     

A data-driven memory model for solving turbulent flows with the pseudo-direct numerical simulation method

It is well known that the inherent three-dimensional and unsteady nature of turbulent flows is a stumbling block for all approaches aimed at resolving their spatial and temporal variability. The pseudo-direct numerical simulation (P-DNS) method for turbulent flows, proposed by the authors in a previous publication, focused on resolving the spatial variability, leaving the task of solving the temporal evolution to a highly simplified, parameter dependent model, to be adjusted in a case by case basis. Although some auspicious results were obtained, the applicability of P-DNS for problems of industrial interest required a more sophisticated method to deal with the temporal variability. In this sense, the present work proposes a new, parameter free, data-driven memory model for P-DNS. The model is based on the study of off-line DNS solutions of turbulent flows transitioning between statistically steady states in simple domains. The new P-DNS model is tested and successfully compared against existing methods in selected three-dimensional turbulent flows.