Crystal Engineering of Schiff Base Zn(II) and Cd(II) Homo- and Zn(II)M(II) (M = Mn or Cd) Heterometallic Coordination Polymers and Their Ability to Accommodate Solvent Guest Molecules.

Based on solvothermal synthesis, self-assembly of the heptadentate 2,6-diacetylpyridine bis(nicotinoylhydrazone) Schiff base ligand (H2L) and Zn(II) and/or Cd(II) salts has led to the formation of three homometallic [CdL]n (1), {[CdL]∙0.5dmf∙H2O}n (2) and {[ZnL]∙0.5dmf∙1.5H2O}n (3), as well as two heterometallic {[Zn0.75Cd1.25L2]∙dmf∙0.5H2O}n (4) and {[MnZnL2]∙dmf∙3H2O}n coordination polymers. Compound 1 represents a 1D chain, whereas 2-5 are isostructural and isomorphous two-dimensional structures. The entire series was characterized by IR spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction and emission measurements. 2D coordination polymers accommodate water and dmf molecules in their cage-shaped interlayer spaces, which are released when the samples are heated. Thus, three solvated crystals were degassed at two temperatures and their photoluminescent and adsorption-desorption properties were recorded in order to validate this assumption. Solvent-free samples reveal an increase in volume pore, adsorption specific surface area and photoluminescence with regard to synthesized crystals.

Synthesis, crystal structure and biological activity of 2-hydroxyethylammonium salt of p-aminobenzoic acid.

p-Aminobenzoic acid (pABA) plays important roles in a wide variety of metabolic processes. Herein we report the synthesis, theoretical calculations, crystallographic investigation, and in vitro determination of the biological activity and phytotoxicity of the pABA salt, 2-hydroxyethylammonium p-aminobenzoate (HEA-pABA). The ability of neutral and anionic forms of pABA to interact with TIR1 pocket was investigated by calculation of molecular electrostatic potential maps on the accessible surface area, docking experiments, Molecular Dynamics and Quantum Mechanics/Molecular Mechanics calculations. The docking study of the folate precursor pABA, its anionic form and natural auxin (indole-3-acetic acid, IAA) with the auxin receptor TIR1 revealed a similar binding mode in the active site. The phytotoxic evaluation of HEA-pABA, pABA and 2-hydroxyethylamine (HEA) was performed on the model plant Arabidopsis thaliana ecotype Col 0 at five different concentrations. HEA-pABA and pABA acted as potential auxin-like regulators of root development in Arabidopsis thaliana (0.1 and 0.2 mM) and displayed an agravitropic root response at high concentration (2 mM). This study suggests that HEA-pABA and pABA might be considered as potential new regulators of plant growth.

N-acetyl-4-[(2-hydroxybenzylidene)amino]benzenesulfonamide monohydrate and N-acetyl-4-[(5-bromo-2-hydroxybenzylidene)amino]benzenesulfonamide monohydrate.

Molecules of the title compounds, C15H14N2O4S.H2O and C15H13BrN2O4S.H2O, adopt an E configuration about the azomethine C=N double bond. In both molecules, the two benzene rings and the azomethine group are practically coplanar, as a result of intramolecular hydrogen bonds involving the hydroxy O atom and azomethine N atom. The angular disposition of the bonds about the S atom deviates significantly from that of a regular tetrahedron. In the crystal structures, both compounds form two-dimensional layers parallel to the (100) plane.

The monoclinic polymorph of rac-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetraazoniacyclotetradecane bis(hexafluorogermanate) tetrahydrate.

X-ray data were obtained for the monoclinic polymorph of rac-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetraazoniacyclotetradecane bis(hexafluorogermanate) tetrahydrate, (C(16)H(40)N(4))[GeF(6)](2).4H(2)O. The tetraaza-macrocyclic cations lie across inversion centers in space group P2(1)/c. Water molecules and [GeF(6)](2-) anions form zigzag chains, which alternate in a three-dimensional network with the macrocyclic cations. The structure is sustained by multiple hydrogen bonds.