2-[((E)-2-{2-[(E)-2-Hy­droxy­benzyl­idene]hydrazinecarbon­yl}hydrazinyl­idene)meth­yl]phenol

The mol­ecule of the title compound, C15H14N4O3, is completed by the application of crystallographic twofold symmetry, with the carbonyl group lying on the rotation axis. The mol­ecule is close to planar: the greatest deviation of a torsion angle from 0° is 7.3 (2)° about the bond linking the phenol ring to the rest of the mol­ecule. An intra­molecular O—H⋯N(imine) hydrogen bond is formed in each half of the mol­ecule. The carbonyl O atom is anti with respect to the amine H atoms and this allows for the formation of N—H⋯O(hydrox­yl) hydrogen bonds in the crystal, which results in supra­molecular layers lying parallel to (100)

N′-[(2Z)-4-Oxo-4-phenyl­but-2-en-2-yl]pyridine-4-carbohydrazide

There are significant twists in the title compound, C16H15N3O2, as seen in the dihedral angle between the benzene and adjacent but-2-enal group [29.26 (4)°] and between the pyridine ring and amide group [24.79 (6)°]. A twist is also evident around the hydrazine bond [the C—N—N—C torsion angle is −138.25 (13)°]. The conformation about the ethene bond is Z. An intra­molecular N—H⋯O hydrogen bond involving the benzoyl O atom and leading to an S(6) motif is formed. Significant delocalization of π-electron density is found in this part of the mol­ecule. In the crystal, helical supra­molecular chains aligned along the b axis and mediated by N—H⋯O hydrogen bonds are formed

(E,E)-N′-{4-[(2-Benzoyl­hydrazin-1-yl­idene)meth­yl]benzyl­idene}benzo­hydrazide

In the title compound, C22H18N4O2, the mol­ecules lie across an inversion centre. The dihedral angle between the mean planes of the central and terminal benzene rings is 66.03 (2)°. The mol­ecule displays trans and anti conformations about the C=N and N—N bonds, respectively. In the crystal, N—H⋯O hydrogen bonds, with the O atoms of C=O groups acting as acceptors, link the mol­ecules into a chain along [101]

(E)-4-{2-[(2-Hy­droxy­naphthalen-1-yl)methyl­idene]hydrazinecarbon­yl}pyridinium nitrate

The title compound, C17H14N3O2 +·NO3 −, is an aroylhydrazone-based material consisting of a 4-(hydrazinecarbon­yl)pyridinium cation and a nitrate anion. In the cation, the dihedral angle between the benzene ring and the naphthalene ring system is 2.20 (7)°. In the cation, the configuration about the C=N bond is E. There is an intra­molecular O—H⋯N hydrogen bond in the cation, and the supra­molecular structure is stabilized by inter­molecular N—H⋯O hydrogen bonds and weak C—H⋯O contacts between the cation and the nitrate anion

Synthesis, Structural Characterization, and Electrochemical Studies of New Oxovanadium(V) Complexes Derived from 2-Furanoylhydrazon Derivatives

Five monooxovanadium(V) complexes [VO(L1)(OCH3)(OHCH3)] (1), [VO(L2)(OCH3)(OHCH3)] (2), [VO(L3)(OCH3)(OHCH3)] (3), [VO(L4)(OCH3)(OHCH3)] (4), and [VO(L5)(OCH3)(OHCH3)] (5) were synthesized and characterized by IR, NMR UV-Vis, and single-crystal structure analysis [H2L1=(E)-N′-((2-hydroxynaphthalen-1-yl)methylene)furan-2-carbohydrazide, H2L2=(E)-N′-(2-hydroxybenzylidene)furan-2-carbohydrazide, H2L3(E)-N′-(5-bromo-2-hydroxybenzylidene)furan-2-carbohydrazide, H2L4=(E)-N′-(2-hydroxy-5-nitrobenzylidene)furan-2-carbohydrazide, H2L5=(E)-N′-(2-hydroxy-5-iodobenzylidene)furan-2-carbohydrazide]. In all 1–3 structures the vanadium atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base dianion (L1–3)2− and one methoxylato group occupying the sites of the equatorial plane. The oxo group and one methanol molecule occupy the apical sites. In the complexes 1, 2, and 3 the conformation of 2-furanyl oxygen atom relative to the carbohydrazide oxygen atom is s-anti, s-anti/s-syn, and s-syn at 293 K, respectively. Cyclic voltammetric experiments of the solution species 1–5 in DMSO revealed a quasi-reversible behavior

(E)-N′-[(2-Hy­droxy­naphthalen-1-yl)methyl­idene]-4-methyl­benzene­sulfono­hydrazide

In the title compound, C18H16N2O3S, the dihedral angle between the planes of the benzene ring and the naphthyl ring system is 83.37 (10)°. An intra­molecular O—H⋯N hydrogen bond occurs. Inter­molecular N—H⋯O hydrogen bonds stabilize the crystal structure. There is a π–π inter­action between the naphthyl ring systems [centroid–centroid distance = 3.7556 (15) Å]. In addition, naphth­yl–tolyl and naphth­yl–naphthyl C—H⋯π inter­actions are observed

Mn oxide as a kinetically dominant “true” catalyst for water oxidation

Nature uses an Mn cluster for water oxidation, and thus, water oxidation using Mn clusters is interesting when used in artificial water-splitting systems. An important question is whether an Mn cluster is a true catalyst for water oxidation or not. Herein, an Mn–K cluster was investigated for electrochemical water oxidation to find the true and the kinetically dominant catalyst using X-ray absorption spectroscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electrochemical methods. The experiments showed that conversion into nanosized Mn oxide occurred for the cluster, and the nanosized Mn oxides are the true catalyst for water oxidation

N′-[(E)-2-Hy­droxy-5-iodo­benzyl­idene]furan-2-carbohydrazide monohydrate

The organic mol­ecule of the title monohydrate, C12H9IN2O3·H2O, features a disordered furyl ring with the major component [site occupancy = 0.575 (18)] having the carbonyl O and furyl O atoms syn, and the other conformation having these atoms anti. The mol­ecule is slightly twisted with the dihedral angle between the benzene and furyl rings being 10.3 (6)° (major component). An intra­molecular O—H⋯N(imine) hydrogen bond is formed. In the crystal, the water mol­ecule accepts a hydrogen bond from an amine H atom, and forms two O—H⋯O(carbon­yl) hydrogen bonds, thereby linking three different carbohydrazide mol­ecules. The result is a supra­molecular layer parallel to (001). The closest contacts between layers are of the type I⋯I, at a distance of 3.6986 (6) Å

{(E)-4-Hy­droxy-N′-[phen­yl(pyridin-2-yl-κN)methyl­idene]benzohydrazide-κ2 N′,O}bis­(nitrato-κ2 O,O′)copper(II)

In the title compound, [Cu(NO3)2(C19H15N3O2)], the coordination geometry around the CuII ion can be described as distorted square-pyramidal, with two N atoms and one O atom from an (E)-4-hy­droxy-N′-[phen­yl(pyridin-2-yl)methyl­ene]benzohydrazide ligand and one nitrate O atom in the basal plane and one nitrate O atom at the apical site. The other two nitrate O atoms also bind to the Cu atom with long Cu—O distances [2.607 (4) and 2.853 (5) Å]. The crystal packing is stabilized by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds