N-2-hydroxy-4-methoxyacetophenone-N'-4-nitrobenzoyl hydrazine: synthesis and structural characterization

Fluoride ions detection in aqueous media by unprecedented ring opening of fluorescein dye: A novel multimodal sensor for fluoride ions and its utilization in live cell imaging

Imidazole functionalized on fluorescein dye was developed as an efficient probe for naked eye and fluorescence determination of fluoride ions. The probe is dramatic color change and very exciting fluorescence turn-on response with the addition fluoride ions. Moreover, fluoride ions triggering leads to the fissure of the spirolactam ring that causes drastic color makes feasible for the naked eye detection of fluoride ions. The mode of binding of fluoride with the probe was proved by ¹H NMR titration experiments and the observed photophysical changes were rationalized by use of DFT calculations. This sensor was more applied to detect fluoride ions in real samples and imaging of fluoride ions through fluorescence imaging in living cells.

Crystal structure of (E)-2,6-di-tert-butyl-4-{[2-(2,4-di-nitro-phen-yl)hydrazinylidene]meth-yl}phenol

The essential part (including all the non-hydrogen atoms except two methyl carbons) of the mol-ecule of the title compound, C21H26N4O5, lies on a mirror plane, which bis-ects the t-butyl groups. The conformation of the C=N bond of this Schiff base compound is E, and there is an intra-molecular N-H⋯O hydrogen bond present, forming an S(6) ring motif. In the crystal, mol-ecules are linked via O-H⋯O hydrogen bonds, forming zigzag chains propagating along the a-axis direction. There are no other significant inter-molecular contacts present.

Crystal structure of (E)-N'-(5-bromo-2-hy-droxy-benzyl-idene)nicotinohydrazide monohydrate

In the title compound, C13H10BrN3O2·H2O, the conformation about the azomethine double bond is E. The mol-ecule exists in the amido form with a C=O bond length of 1.229 (2) Å. There is an intra-molecular O-H⋯N hydrogen bond forming an S(6) ring motif. The whole mol-ecule is almost planar, with an r.m.s. deviation of 0.021 Å for all non-H atoms, and the dihedral angle between the planes of the pyridine and benzene rings is 0.74 (12)°. In the crystal, the water mol-ecule of crystallization links the organic mol-ecules via Ow-H⋯O, Ow-H⋯N and N-H⋯Ow hydrogen bonds and short C-H⋯Ow contacts, forming sheets lying parallel to (100). Within the sheets there is a weak π-π inter-action involving the pyridine and benzene rings [centroid-to-centroid distance = 3.8473 (15) Å]. The sheets are linked via C-H⋯Br inter-actions, forming a three-dimensional network.

Bis{μ-N-[(E)-4-benz-yloxy-2-oxidobenzyl-idene]-4-nitro-benzene-carbo-hydrazidato}bis-[di-aqua-nickel(II)] di-methyl-formamide tetra-solvate

The molecule of the title complex, [Ni₂(C₂₁H₁₅N₃O₅)₂(H₂O)₄]·4C₃H₇NO, is located on an inversion centre. This results in a dimeric Ni^II complex, with the two Ni^II atoms bridged by phenolate O atoms. The tridentate ligand is chelated to each Ni^II atom via one N and two O atoms of the imino­late form of the hydrazide moiety, which has the same conformation as the free ligand. The coordination geometry around each Ni^II ion is slightly distorted octa­hedral. A supra­molecular three-dimensional architecture is created by dominant inter­molecular O—H⋯N, O—H⋯O and C—H⋯O hydrogen-bonding inter­actions. These are augmented by two C—H⋯π inter­actions and a π–π inter­action with a centroid–centroid distance of 3.681 (2) Å.

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 all1–3structures 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 complexes1,2, and3the conformation of 2-furanyl oxygen atom relative to the carbohydrazide oxygen atom iss-anti,s-anti/s-syn, ands-syn at 293 K, respectively. Cyclic voltammetric experiments of the solution species1–5in DMSO revealed a quasi-reversible behavior.

Synthesis and crystal structure of hydroxyacetophenone Schiff bases containing propargyl moiety: solvent effects on UV-visible spectra

Four tetradentate (N(2)O(2)) and tridentate (NO(2)) Schiff base compounds (L1-L4) with propargyl moiety were prepared by the condensation of 1-[2-hydroxy-4-(prop-2-yn-1-yloxy)phenyl]ethanone with various aliphatic amines. The newly synthesized compounds (L1-L4) were characterized on the basis of the results of elemental analysis, thermal analysis, FT-IR, (1)H NMR spectroscopic studies and single crystal X-ray crystallography. The different bands observed in the electronic spectra of the compounds in various organic solvents have been assigned to the proper electronic transitions. The hydrogen bonding and tautomeric equilibria in both of solution and the solid state are explained. The solvatochromism of the synthesized compounds in different solvents in the UV-visible spectra are discussed.

Bach adsorption study for the extraction of silver ions by hydrazone compounds from aqueous solution

Sorbent materials based on a hydrazone Schiff base compound, C₁₄H₁₁BrN₄O₄, were prepared either by immobilizing the ligand into sol-gel (SG1) or bonding to silica (SG2). The sorbent materials were characterized by FT-IR, EDX, SEM, TEM, and TGA. The sorption characteristics of a matrix of eight transition metal ions (Ag⁺, Cu²⁺, Co²⁺, Ni²⁺, Fe³⁺, Pb²⁺, Zn²⁺, and Mn²⁺) using batch method were studied. Several key parameters that affected the extraction efficiency such as pH, contact time, metal ions concentration, and gel size (for SGl) were investigated and optimized. Under the optimized conditions, the physically immobilized hydrazone sorbent (SG1) exhibits highest selectivity towards Ag⁺ ions, while the chemically bonded hydrazone sorbent (SG2) exhibits high extraction for all metal ions tested. However, for practical applications such as the removal and preconcentration of Ag⁺, the physically immobilized sorbent (SG1) is preferred.

Molecular structures, spectral and computational studies on nicotinohydrazides

The FT-IR and the high resolution (1)H and (13)C NMR spectra have been recorded for N'-(2-methyl-3-phenylallylidene)nicotinohydrazide (1) and N'-(2-methyl-3-phenylallylidene)isonicotinohydrazide (2) and analyzed. (1)H-(1)H COSY spectra were also recorded for the hydrazides. The spectral studies reveal that both the hydrazides exist in the keto form. Theoretical calculations were performed for some possible conformations of the hydrazide and the minimum energy conformers are predicted to be the one in which the azomethine protons are syn to N-NH bond. From the optimized structures, HOMO-LUMO energy gap and geometrical parameters were derived and these parameters were compared with the XRD measurements of hydrazide 1. The vibrational frequencies in the ground state have been calculated using DFT and HF methods and compared with the observed frequencies. Non-linear optical (NLO) behaviour of the hydrazides was investigated by the determination of the electric dipole moment mu, the polarizability alpha and the hyperpolarizability beta using B(3)LYP method.

(2Z,N'E)-N'-[(2-Hy-droxy-1-naphth-yl)methyl-idene]furan-2-carbohydrazonic acid

In the title compound, C₁₆H₁₂N₂O₃, the dihedral angle between the mean planes of the naphthalene ring system and the furan ring is 21.3 (6)°. The mol­ecular structure is stabilized by an intra­molecular O—H⋯N hydrogen bond, which generates an S(6) graph-set motif.

2-Hydr-oxy-5-nitro-benzaldehyde 2,4-dinitro-phenyl-hydrazone

In the title compound, C(13)H(9)N(5)O(7), one of the nitro groups is twisted away from the attached benzene ring by 16.21 (8)°. The dihedral angle between the two benzene rings is 4.63 (1)°. The mol-ecular structure is stabilized by intra-molecular N-H⋯O and O-H⋯N hydrogen bonds which generate an S(6) ring motif. The mol-ecules pack as layers parallel to the ab plane; mol-ecules of adjacent layers are linked into chains along the [101] direction through N-H⋯O hydrogen bonds.