Hydrazine Molecules Research Articles

Emissive Hydrazone-Linked Covalent Organic Frameworks as Highly Sensitive and Selective Sensor for the Hydrazine Detection.

Covalent Organic Frameworks (COFs) exhibit a range of exceptional attributes, including notable porosity, outstanding stability, and a precisely tuned π-conjugated network, rendering them highly promising candidates for fluorescence sensors applications. In this study, the synthesis of two emissive hydrazone-linked COFs designed for hydrazine detection is presented. The partially conjugated structure of the hydrazone linkage effectively weakens the fluorescence quenching processes induced by aggregation. Additionally, the incorporation of flexible structural components further reduces conjugation, thereby enhancing luminescent efficiency. Remarkably, these COFs possess a significant abundance of heteroatoms, enabling distinctive interactions with hydrazine molecules, which in turn results in exceptional selectivity and sensitivity for hydrazine detection. The detection limit of these COFs reaches the nanomolar range, surpassing all previously reported COFs, thereby underscoring their superior performance in chemical sensing applications.

Mechanism of the hydrazine hydrate electrooxidation reaction on metallic Ni electrodes in alkaline media as revealed by electrochemical methods, online DEMS and ex situ XPS

Metallic Ni surface was examined as a catalyst for the hydrazine hydrate oxidation reaction (HHOR) by cyclic voltammetry, chronoamperometry, and online differential electrochemical mass-spectrometry (DEMS). It was found that N2 is the sole gaseous product formed during the HHOR on Ni and 4 electrons are transferred in the process, which corresponds to a complete oxidation of the hydrazine molecule. The mechanism of the HHOR on the Ni surface involves OH− and adsorbed OHads intermediate, the latter improving the rate of the HHOR. Ni catalysts were found to be poisoned during the HHOR, the extent of poisoning depending on the number of surface sites, hydrazine concentration, and the α-Ni(OH)2 coverage. Ex situ X-ray photoelectron spectroscopy (XPS) measurements were performed to characterize the species poisoning Ni surface.

Embedding Ru single atom catalysts on Co3O4 for efficient hydrazine oxidation and direct hydrazine fuel cells

Direct hydrazine fuel cells (DHzFCs) are promising energy conversion devices due to their high energy density and environmental friendliness. However, inefficient hydrazine oxidation (HzOR) remains a key bottleneck in achieving practical fuel cell performance. To address this challenge, precise material design and synthesis are necessary to modulate the electronic structure and maximize the utilization of active sites. Herein, we present a Ru-Co3O4 catalyst, which is synthesized based on a cation exchange strategy through which Ru single atoms are embedded on the surface of Co3O4. Theoretical calculations confirm that Ru single atoms show a stronger hybridization with hydrazine molecules near the Fermi level and significantly lower the energy barrier required for N-containing intermediate formation, contributing to a record-low onset potential of −0.15 V vs. RHE and a working potential of −0.115 V vs. RHE at 10 mA cm−2. The assembled DHzFC using Ru-Co3O4 as the anode catalyst achieves an impressive power output of 310.7 mW cm−2.

A Simulation of Hydrazine Molecule’s Potential Energy Surface using Variational Quantum Eigensolver Algorithm

Quantum computing is a technology that utilizes the principles of quantum mechanics to perform complex computational processes. In this work, we use Qiskit Module from IBM to do quantum computational calculation using Variational Quantum Eigensolver (VQE) algorithm. VQE is a hybrid quantum-classical method that combines a quantum computer to measure energies and a classical computer to process the measurement results and update the parameters of the quantum computer. The purpose of VQE is to find the ground state energy of a chemical system. In the previous study, many of the VQE calculations have been done on simple molecules. So, in this study, we would like to use Hydrazine molecule as our object of VQE calculation. Furthermore, these results will be compared with the results from the classical calculation (MP2, CCSD(T), QCISD(T), and CASSCF) methods for testing the effectiveness of VQE using Unitary Coupled-Cluster Single and Double excitations (UCCSD) Ansatz. The quantum algorithm based on the UCCSD Ansatz led to a simplification of the algorithm by reducing the circuit depth. Then, the possibility to use active space approximation, can be used to reduce the quantum gates while trying to keep a good level of accuracy. In this study, we chose (2,2) and (4,4) active spaces. Based on the results, as we increase the size of the active space during the evaluation of the single-point energy, the estimated ground states obtained from the VQE algorithm yield nearly identical values. Conversely, in CASSCF calculations, expanding the active space introduces more energy corrections, thus making it more sensitive. Additionally, when examining potential energy surfaces, VQE demonstrates results that gradually align with CCSD(T) and QCISD(T) methods.

Switching of photoinduced proton transfer from one six-membered hydrogen-bonded ring to other: a molecule of hydrazine and pH sensor.

The present study describes photophysical properties of 3-(benzo[d]oxazol-2-yl)-5-bromo-2-hydroxybenzaldehyde (HBOB) and (E)-2-(benzo[d]oxazol-2-yl)-4-bromo-6-(hydrazonomethyl)phenol (HBON) molecules with asymmetric two-way proton transfer sites. The purpose of this study is to know the direction of ESIPT out of the two-way proton transfer pathways in these molecules in both the solid and solution state. The steady state and time-resolved spectral behaviour of HBOB and HBON and a comparison of the spectral features with the two distinct control compounds 2-(benzo[d]oxazol-2-yl)-4-bromophenol (HBO) and (E)-4-bromo-2-(hydrazonomethyl)phenol (HBN) having single 6-membered hydrogen bonded network reveal that HBOB undergoes imine-amine photoisomerisation by proton transfer towards the oxazole side and HBON undergoes towards the hydrazone side with characteristic Stokes' shifted emission. Proton transfer forms with the red shifted emission of these molecules shows fast decay than the locally excited state. In the solid state, extremely high fluorescence intensity was observed, following a similar type of ESIPT pattern. Calculated ground (S0) and excited state (S1) energy barriers for the PT process obtained using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) corroborate the unidirectional excited state intramolecular proton transfer (ESIPT) process for HBOB and HBON, and the theoretical spectral features validate our experimental absorption and emission spectra well. Interestingly, the unique unidirectional ESIPT behaviour of HBOB was utilised to detect hydrazine both in solution and solid phases. On the other hand, HBON was found to be a good fluorescence pH sensor with a ratiometric color change from yellow to green in acidic and basic media.

Maximizing urea-/hydrazine-assisted electrolytic hydrogen production by defective nickel copper selenide nanostructures

Replacing the formidable oxygen evolution reaction (OER) with other oxidizable species is an appealing approach to attain highly efficient hydrogen (H2) generation with a lower potential. Accordingly, the kinetically favorable electrooxidation reaction of urea or hydrazine molecule can increase the return on energy profiteering and prevent pollutant emission. Thus, opening up an innovative direction to replace the sluggish OER and generate high-purity H2 gas via an energy-saving approach. Thus, constructing highly efficient and stable bifunctional electrodes/electrocatalysts is a key to realize economical and sustainable H2 production. In this work, we developed defect-enriched two-dimensional (2D) heterogeneous nickel copper selenide (D/Ni-Cu-Se) on a conductive Ni foam (NF) scaffold as an integrated bifunctional electrocatalytic electrode for energy-saving for H2 production. The self-supported D/Ni-Cu-Se/NF electrode with a regulated interfacial property and abundant metal defects is fabricated through a hydrothermal approach and a metal-defect engineering route. The thus-prepared electrode exhibits a high electrocatalytic performance for both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) in a 1.0 M KOH electrolyte, achieving the catalytic current density of 10 mA cm−2 at a potential of 87.7 mV and 1.335 V vs. RHE, respectively. In relation, the two-electrode urea-water electrolyzer and hydrazine-water electrolyzer utilizing the bifunctional D/Ni-Cu-Se/NF as both the cathode and anode electrodes reveal a cell voltage of ∼ 1.395 V and 0.268 V at 10 mA cm−2 in 1.0 M KOH/0.33 M urea and 1.0 M KOH/0.25 M hydrazine, respectively, which is much less than that of conventional water electrolysis (1.572 V). The implemented electrolyzer systems consequently endow high long-term durability over 48 h of continuous electrolysis, indicating that the defect-rich D/Ni-Cu-Se/NF can serve as a potential bifunctional electrocatalyst with an outstanding electrolysis performance and excellent stability for H2 generation. Indeed, such a novel bifunctional electrode configuration and corresponding electrolysis performances are much desired for energy-saving electrolytic H2 production and pave the way for exploring highly efficient and robust electrodes.

4-Methyl/Phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-ones Synthesis: Mechanistic Pathway Study and Single-Crystal X-ray Analysis of the Intermediates

The synthesis of 4-methyl/phenyl-1,2,5,6-tetraazafluoranthen-3(2H)-one 4 and 7 has been reported with ninhydrin via a reaction first with ethyl acetoacetate or ethyl benzoylacetate and then a reaction of the resultant esters with hydrazine hydrate. The mechanism of hydrazinolysis and cyclization to obtain tetraazafluoranthen-3(2H)-ones is ambiguous, and the previously proposed mechanism was not based on facts because the actual intermediates were not isolated. Herein, the important intermediates involved in the hydrazinolysis–cyclization mechanistic pathway were isolated and characterized using NMR and X-ray single-crystal analysis. The intermediates demonstrate that the reaction carried out via two hydrazinolysis–cyclization reactions, the first of which includes the condensation of one hydrazine molecule with two ketone groups and the second of which includes the reaction of another hydrazine molecule with the ester and then condensation with the other ketone group. The stability of hydrazide 11 enabled the hydrazine to reduce the carbonyl of the ketone group to form 12 via a Wolff–Kishner-like reduction. The structure of the three intermediates was confirmed using X-ray crystallographic analysis. It was found that the three fused ring systems deviated from planarity to different extents, with their deviation from being coplanar reaching up to 5.3°. The possible non-covalent interactions which control the molecular packing of these intermediates were elucidated with the aid of Hirshfeld analysis.

Directional manipulation of electron transfer in copper/nitrogen doped carbon by Schottky barrier for efficient anodic hydrazine oxidation and cathodic oxygen reduction

Development of bifunctional hydrazine oxidation and oxygen reduction electrocatalysts with high activity and stability is of great significance for the implementation of direct hydrazine fuel cells. Combining zero-dimensional metal nanoparticles with three-dimensional nitrogen-doped carbon nanosheets is an attractive strategy for balancing performance and cost. However, the precise construction of these composites remains a significant challenge, and thorough study of their interaction mechanisms is lacking. Herein, the CuNPs/CuSA-NPCF catalyst was constructed by anchoring copper nanoparticles on a three-dimensional nitrogen-doped porous carbon nanosheet framework through coordination of polyvinyl pyrrolidone and copper ions. The Schottky barrier of metal–semiconductor matched the Fermi level of the rectifying contact, thus enabling directional electron transfer. The resulting electron-deficient Cu nanoparticles surface exhibited Lewis acidity, which was beneficial to adsorption of hydrazine molecule. While the electron-enriched Cu–N4/carbon surface improved the adsorption of oxygen molecule, and accelerated electron supply from Cu-N4 active sites to various oxygen intermediates. The CuNPs/CuSA-NPCF Mott-Schottky catalyst exhibited excellent catalytic activity for hydrazine oxidation reaction and oxygen reduction reaction in an alkaline media. The directional manipulation of electron transfer in heterogeneous materials was an attractive universal synthesis method, providing new approach for the preparation of efficient and stable hydrazine fuel cell catalysts.

A Multifunctional Coordination Polymer Constructed by Viologen Derivatives: Photochromism, Chemochromism, and MnO4- Sensing.

A multifunctional Cd-based coordination polymer based on a viologen derivative and a secondary carboxylic ligand, namely, {[Cd2(bcbp)(pta)2 (H2O)]·2H2O}n (1, H2bcbpCl2 = 1,1'-bis(4-carboxyphenyl)-(4,4'-bipyridinium) dichloride, H2pta = p-phthalic acid), has been solvothermally synthesized and structurally characterized. Compound 1 is a 3D framework built on {Cd2(pta)2 (H2O)}n net with square channels which intalls bcbp ligands at the diagonal position of the two adjacent square channels. Notably, compound 1 exhibits a reversible photochromic transformation between yellowish gray and dark green under xenon light irradiation, which should be attributed to the formation of free viologen radicals. Furthermore, compound 1 also displays a chemochromic phenomenon from yellowish gray to dark green after exposure to ammonia and hydrazine, which could be ascribed to the generation of viologen radicals and charge-transfer complexes triggered by nucleophilic attack of electron-rich ammonia and hydrazine molecules to the electron-deficient viologen moiety in the bcbp ligand. Moreover, compound 1 is capable of quickly and selectively detecting MnO4- with a high quenching coefficient and a low limit of detection via a luminescent quenching process caused by the competitive absorption of excitation energy.

Self-supported iron-doped nickel sulfide as efficient catalyst for electrochemical urea and hydrazine oxidation reactions

The electrochemical oxidation of urea and hydrazine over self-supported Fe-doped Ni3S2/NF (Fe–Ni3S2/NF) nanostructured material is presented. Among the various reaction conditions Fe–Ni3S2/NF-2 prepared at 160 °C for 8 h using 0.03 mM Fe(NO3)3 shows the best results for the hydrazine and urea oxidation reactions. The potential values of 0.36, 1.39, and 1.59 V are required to achieve the current density of the 100 mA cm−2 in 1 M hydrazine (Hz), 0.33 M urea, and 1 M KOH electrolyte, respectively. The onset potential in 1 M KOH, 0.33 M Urea +1 M KOH, and 1 M Hz + 1 M KOH values are 1.528, 1.306, and 0.176 respectively. The Fe–Ni3S2/NF-2 shows stable performance at 10 mA cm−2 until 50 h and at 60 mA cm−2 over the 25 h. A cell of PtC//Fe–Ni3S2/NF-2 requires the potential of 0.49, 1.46, and 1.59 V for the hydrogen production in 1 M Hz + 1 M KOH, 0.33 M Urea +1 M KOH, and 1 M KOH electrolyte, respectively, at a current density of 10 mA cm−2, and almost 90% stable for the hydrogen production over the 80 h in all electrolytes. The improvement of the chemical kinetics of urea and hydrazine oxidation is due to the synergistic effect of the adsorption and fast electron transfer reaction on Fe–Ni3S2/NF-2. The doped Fe ion facilitates the fast electron transfer and the surface of Ni3S2 support to the urea and hydrazine molecule adsorption.

Highly efficient catalytic debromination of tetrabromodiphenyl ether with hydrazine as reducing agent: The role of the interaction between the catalyst and the reducing agent

It is still urgently needed to clarify how the reductive dehalogenation is accelerated by the interaction between the catalyst and the reducing agent. In the present work, both Pd and Cu were observed to induce the debromination of 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) with hydrazine hydrate (N2H4·H2O) as reducing agent. In the case of Pd system, all the added BDE47 was debrominated to bromine-free products within 20 min. However, much different debromination behaviors of BDE47 were observed when Cu was used as the catalyst: in the initial stage the debromination efficiency of BDE47 could reach up to 55.3% within 0.5 min; nevertheless the complete debromination could not be achieved by prolonging reaction time. With the aid of DFT calculations, the above-mentioned great differences were attributed to the affinity of Pd to both H and N atoms, and strong Cu–N coordination existed between Cu and the adsorbed hydrazine molecules. The dissociation energy for the cleavage of N–H and N-N bonds of N2H4·H2O adsorbed on Cu was very low, and hence the debromination of BDE47 was ultra-fast due to the spontaneously cleavage of N–H bond but it was inhibited at the later stage by the generated ammonium species (poisoning effect to the Cu catalyst) due to N-N bond cleavage. In contrast, the dissociation energy for the cleavage of N–H bond on the surface of Pd was higher and no ammonium was detected. These guarantee the continuously fast and complete debromination of BDE47 and its intermediates. These new insights to the catalytic mechanism through the interaction between the catalyst and the reducing agent will help to construct an efficient system to remove halogenated organic pollutants.

Hydrazine Hydrate Intercalated 1T-Dominant MoS2 with Superior Ambient Stability for Highly Efficient Electrocatalytic Applications.

Metallic 1T-phase MoS2 exhibits superior hydrogen evolution reaction (HER) performance than natural 2H-phase MoS2 owing to its higher electrical conductivity and abundance of active sites. However, the reported 1T-MoS2 catalysts usually suffer from extreme instability, which results in quick phase transformation at ambient conditions. Herein, we present a facile approach to engineer the phase of MoS2 by introducing intercalated hydrazine. Interestingly, the as-synthesized 1T-dominant MoS2 sample demonstrates excellent ambient stability without noticeable degradation for 3 months. Additionally, the 1T-dominant MoS2 exhibits superior electrical conductivity (∼700 times higher than that of 2H-MoS2) and improved electrochemical catalytic performance (current density ∼12 times larger than that of 2H-MoS2 at an overpotential of 300 mV vs the reversible hydrogen electrode, RHE). Through experimental characterizations and density functional theory (DFT) calculation, we conclude that the stabilization of the metallic phase could be attributed to the electron donation from hydrazine molecules to the adjacent Mo atoms. The phase control strategy in this work provides a guideline to develop other highly efficient and stable two-dimensional (2D) electrocatalysts.

Synthesis and spectroscopic characterizations of manganese(II), iron(III), copper(II) and zinc(II) hydrazine complexes as catalytic activity agents

ABSTRACT. This article deals with the preparation and coordination of NH2—NH2 hydrazine molecule compounds. The hydrazine sulfate complexes of Mn(II), Fe(III), Cu(II), and Zn(II) were prepared. These complexes were characterized by elemental, infrared, conduction, electron absorption spectroscopy, magnetic susceptibility, thermogravimetric analyses, X-ray powder diffraction (XRD) patterns and atomic force microscopy (AFM) studies. The magnetic measurements were confirmed that the Mn(II), Fe(III), Cu(II), and Zn(II) hydrazine complexes have an octahedral geometric structure. Thermogravimetric and its differential thermogravimetric analysis referred that all complexes passed through two-to-three thermal degradation steps with solid metal sulfate as a residual product. The infrared spectra inferred that the NH2—NH2 ligand forms complexes through nitrogen atoms of the—NH2 moiety, while the elemental analysis indicates [M(NH2—NH2)3]SO4 (where M = Mn(II), Cu(II), and Zn(II)) while the iron(III) complexes have the [Fe2(NH2—NH2)4(SO4)2]SO4 formula of coordination compounds, NH2—NH2 acts as a double bond. Both XRD and AFM analysis deduced that the synthesized hydrazine metal complexes were found to be in nano scale range 10—30 nm.
 
 KEY WORDS: Hydrazine, FTIR, AFM, XRD, Transition metals
 Bull. Chem. Soc. Ethiop. 2022, 36(1), 33-44. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i1.4

Towards N-N-Doped Carbon Dots: A Combined Computational and Experimental Investigation.

The introduction of N doping atoms in the carbon network of Carbon Dots is known to increase their quantum yield and broaden the emission spectrum, depending on the kind of N bonding introduced. N doping is usually achieved by exploiting amine molecules in the synthesis. In this work, we studied the possibility of introducing a N–N bonding in the carbon network by means of hydrothermal synthesis of citric acid and hydrazine molecules, including hydrated hydrazine, di-methylhydrazine and phenylhydrazine. The experimental optical features show the typical fingerprints of Carbon Dots formation, such as nanometric size, excitation dependent emission, non-single exponential decay of photoluminescence and G and D vibrational bands in the Raman spectra. To explain the reported data, we performed a detailed computational investigation of the possible products of the synthesis, comparing the simulated absorbance spectra with the experimental optical excitation pattern. The computed Raman spectra corroborate the hypothesis of the formation of pyridinone derivatives, among which the formation of small polymeric chains allowed the broad excitation spectra to be experimentally observed.

Pyrazolo[3,4-b]pyridin-3(2H)-one derivatives: Synthesis and their investigation of mosquito larvicidal activity

In this study, nitrogen-nitrogen bonds containing compounds such as hydrazine derivatives are examined. There are relatively few hydrazine molecules in nature, but some have been isolated from plants, marine organisms and microorganisms. Thus, hydrazine molecules are widely used in the manufacture of synthetic catalysts, agriculture chemicals, pesticides, and also cause irreversible pollution to air, water, and soil. Hydrazine compounds were evaluated via larvicidal profile in a stagnant water system. According to the above observation, new 1H-pyrazolo[3,4-b]pyridin-3(2H)-one derivatives can be synthesized via catalyst free green chemistry approach.A range of FT-IR spectroscopic measures, 1H and 13C NMR, as well as mass spectra, were used to characterize the compounds (2a-e). The compound 2e was more potent (95,6% mortality, LD50: 20.1 µg/ mL) against Culex quinquefasciatus than natural pyrazolidine derivatives. Therefore, the objective of this study, prospered with a few of the pyrzolopyridine hydrazine models, which are demonstrated to be low toxic environmentally safe and high potential larvicidal profile.

Hydrogen generation from hydrazine on N4 moieties graphene embedded by vanadium metal, DFT calculation

In this article, the catalytic effect of the VN4 on graphene has been studied for the decomposition of hydrazine (N2H4) with Density Functional Theory (DFT) calculations using DFT-D3 in the method of Grimme. The adsorb energy, a Bader charge transfer, charge density difference, and partial density of states were examined. Hydrazine decomposition is investigated in two different ways; the NN bond cleavage for N2H4→NH2+NH2 reaction and the NH bond cleavage for N2H4→N2H3+H to produce hydrogen production. According to our result, the gauche conformer of hydrazine is the most stable formation on the modified graphene surface. The interaction of hydrazine molecule with the surface is chemical adsorption through adding V impurity. The NN bond split for V embedded surface has lower activation energy than that of the NH bond cleavages. It is promising to investigate hydrogen generation from hydrazine on the high-performance graphene-like catalyst.

Synthesis of nanocubic shape controlled Gold-Prussian blue nanocomposite for enhanced electrocatalytic hydrazine oxidation

• A facile wet chemical method used for the synthesis of nano cubic shape controlled Au-PB-NCs. • Au-PB-NC/GCE shows 13 times higher catalytic current density of hydrazine than pristine PB-NCs. • The sensitivity of Au-PB-NCs/GCE is 111 μA.cm −2 μM −1 with LOD of 0.709 µM for sensing of hydrazine. Herein, we report for the first time, facile chemical synthesis of gold nanoparticles embedded in nano-cubic shaped prussian blue (Au-PB-NCs). To understand the role of gold nanoparticles (AuNPs) present in the Au-PB-NCs, the same chemical method is used without involving gold precursor solution for pristine prussian blue nanocubes (PB-NCs). For the proof-of-concept experiment, both Au-PB-NCs and PB-NCs are modified on glassy carbon electrodes (it is called as Au-PB-NCs/GCE and PB-NCs/GCE respectively) to study the electrocatalytic activity of hydrazine molecules as a model system. The exact size of the PB-NCs and the nature of the distribution of AuNPs into the Au-PB-NCs matrix are confirmed by high-resolution transmission electron microscopy (HR-TEM) and high-angle annular dark-field scanning transmission electron microscopic (HAADF-STEM) analysis. X-ray diffraction (XRD) and X-ray photon electron microscopy (XPS) results reveal that the PB-NCs has high crystalline and the oxidation state of Au is Au 0 and Au + in Au-PB-NCs. Compared with PB-NCs/GCE, the Au-PB-NCs/GCE showed higher redox current density and improved charge transfer kinetics in electrochemical measurements. Remarkably, it exhibits higher electrocatalytic oxidation current and excellent amperometric response with the linear range of 0–40 µM for hydrazine molecule when compared with PB-NCs/GCE. The calculated low detection limit and sensitivity value of Au-PB-NCs/GCE is 0.709 µM and 111 µA. cm −2 . µM −1 , respectively, which are comparable with reported literature. The selectivity and stability of electrooxidation of hydrazine molecule on fabricated Au-PB-NCs/GCE platform is investigated by amperometric method. The obtained results clearly indicate that Au-PB-NCs/GCE has excellent stability and selectivity towards hydrazine sensing without the impact of other interference. Also, the developed Au-PB-NCs/GCE sensor platform is applied to the real water samples analysis and showed the results of good recovery, reproducibility and repeatability, which implies its feasibility for realistic application in hydrazine estimation.

Hydrazine intercalated iron sulfide (N2H4)1-xFe2+δS2: Synthesis and characterization

The discovery of superconductivity in anti-PbO-type FeS has attracted great interest in the intercalation compounds of FeS. However, it is much more difficult to synthesize intercalates of FeS than to synthesize intercalates of FeSe. Here, we report a novel intercalation compound of FeS with chemical composition of (N2H4)1-xFe2+δS2 (x ​~ ​0.25, δ ​~ ​0.1), which is synthesized via a combination of self-flux solid state method and hydrothermal route. The successful intercalation of hydrazine was confirmed by X-ray diffraction, thermogravimetric analyses and attenuated total internal reflection-Fourier transform infrared spectroscopy, while the maintenance of anti-PbO-type FeS layer in the structure was verified by transmission electron microscopy and Raman spectroscopy. Magnetic and resistivity measurements show that (N2H4)1-xFe2+δS2 is a ferromagnetic metal rather than a superconductor. The low-temperature ferromagnetism may be caused by the intercalated hydrazine molecules or interlayer iron ions and the absence of superconductivity should be closely related to the ferromagnetic ordering.

Physical achirality in geometrically chiral rotamers of hydrazine and boranylborane molecules.

The diagonal components and the trace of tensors which account for chiroptical response of the hydrazine molecule N2 H4 , that is, static anapole magnetizability and frequency-dependent electric dipole-magnetic dipole polarisability, are a function of the H─N─N─H dihedral angle. They vanish for symmetry reasons at ϕ=0° and ϕ=180°, corresponding respectively to C2v and C2h point group symmetries, that is, cis and trans conformers characterized by the presence of molecular symmetry planes. Nonetheless, vanishing diagonal components have been observed also in the proximity of H─N─N─H=90°, in which the point group symmetry is C2 and hydrazine is unquestionably chiral. In the boranylborane molecule B2 H4 , assuming the B─B bond in the y direction, the ayy component of the anapole magnetizability tensor approximately vanishes for dihedral angles H─B─B─H corresponding to chiral rotamers which belong to D2 symmetry. Such anomalous effects have been ascribed to physical achirality of these conformers, that is, to their inability to sustain electronic current densities inducing either anapole moments, or electric and magnetic dipole moments, about the chiral axis connecting heavier atoms, as well as perpendicular directions. In other terms, the structure of certain geometrically chiral rotamers may be such that neither toroidal nor helical flow, which determine chiroptical phenomenology, can take place in the presence of perturbing fields parallel or orthogonal to the chiral axis.

5-(R)BENZYLIDENE-2,2-DIMETHYL-1,3-DIOXANE-4,6-DIONES IN SYNTHESIS OF AROMATIC OXIMES, THIOSEMICARBAZONES AND HYDRAZONES

The behavior of some derivatives of Meldrum's acid, namely, 5-(R)benzylidene-2,2-dimethyl-1,3-dioxane-4,6-diones (a well-known synthetic platform) was studied with mono- and biazanucleophiles (hydrochloric hydroxylamine, thiosemicarbazide, hydrazine hydrate). The reaction of the reagents was carried out in acetic acid in a 1:1 molar ratio at 75 °C for 6-8 h, which resulted in aromatic oximes, thiosemicarbazones and hydrazones. The synthesis of (E)-4-chlorobenzaldoxime, (E)-N-(4-nitrobenzylidene) hydroxylammonium chloride, (E)-2-(4-chloro)- and (E)-2-(4-nitrobenzylidene) hydrazine-1-carbothioamides is probably accompanied by the formation of the Michael β-adduct with the subsequent elimination of Meldrum's acid. The interaction of nitrobenzylidene dioxanedione with hydrazine hydrate occurs to form a mixture of (E)-N-(4-nitrobenzylidene) acetohydrazide, (E)-(4-nitrobenzylidene) hydrazine and acetate of the latter in a ratio of 17:3:1, found from the integral signal intensity in the 1Н NMR spectrum (the ratio of similar products was 6:2:1 for chlorobenzylidene dioxanedione). It has been shown that during the reaction the studied substrates are attacked by two hydrazine molecules at the arylidene fragment and the carboxyl group of the opened dioxane cycle of Meldrum's acid. Further, the intermediates are recondensed to form hydrazones and acetylhydrazides. The latters interact with the aromatic aldehydes arising under these conditions as a result of the Knoevenagel retro-reaction of the substrates, with the formation of major products, mixtures of (E)-N-(4-chloro)- or (E)-N-(4-nitrobenzylidene) acetohydrazides. Thus, under the selected conditions, in contrast to the common mechanism presented in the periodicals, no formation of N-heterocyclic systems is observed. The structure of the compounds obtained was confirmed on the basis of 1H, 13C NMR spectroscopy data, as well as elemental analysis. Methods of two-dimensional heteronuclear correlation spectroscopy (HSQC) were also used for more reliable identification of the signals of the products (the components of mixtures).