Syntheses, characterization and molecular structures of calcium(II) and copper(II) complexes bearing O2-chelate ligands: DNA binding, DNA cleavage and anti-microbial study

Syntheses and Characterization of Main Group, Transition Metal, Lanthanide, and Actinide Complexes of Bidentate Acylpyrazolone Ligands

The synthesis of acylpyrazolone salts and their complexes of main group elements, transition metals, lanthanides, and actinides are described and characterized inter alia by means of single-crystal X-ray crystallography, NMR, and IR spectroscopies. The complexes consist of two, three, or four acylprazolone ligands bound to the metal atom, resulting in a structurally diverse set of coordination complexes with (distorted) octahedral, pentagonal-bipyramidal, or antiprismatic arrangements. Several complexes proved to be polymeric in the solid state including heterobimetallic sodium/lanthanide coordination polymers. A selection of the polymeric compounds was analyzed via TG/DTA measurements to establish their stability. The ligands, in turn, were readily synthesized in good yields from commercially available hydrazine hydrochloride salts. These findings demonstrate that acylpyrazolone ligands can form complexes with metals of varying ionic radii, highlighted by their utility in other areas such as analytical and metal organic framework chemistry.

Copper(II) Complexes of 5-Fluoro-Salicylaldehyde: Synthesis, Characterization, Antioxidant Properties, Interaction with DNA and Serum Albumins

The synthesis, characterization and biological profile (antioxidant capacity, interaction with calf-thymus DNA and serum albumins) of five neutral copper(II) complexes of 5-fluoro-salicylaldehyde in the absence or presence of the N,N'-donor co-ligands 2,2'-bipyridylamine, 2,9-dimethyl-1,10-phenanthroline, 1,10-phenanthroline and 2,2'-bipyridine are presented herein. The compounds were characterized by physicochemical and spectroscopic techniques. The crystal structures of four complexes were determined by single-crystal X-ray crystallography. The ability of the complexes to scavenge 1,1-diphenyl-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radicals and to reduce H₂O₂ was investigated in order to evaluate their antioxidant activity. The interaction of the compounds with calf-thymus DNA possibly takes place via intercalation as suggested by UV-vis spectroscopy and DNA-viscosity titration studies and via competitive studies with ethidium bromide. The affinity of the complexes with bovine and human serum albumins was examined by fluorescence emission spectroscopy revealing the tight and reversible binding of the complexes with the albumins.

Zinc(II) Complex with Pyrazolone-Based Hydrazones is Strongly Effective against Trypanosoma brucei Which Causes African Sleeping Sickness

Two pyrazolone-based hydrazones H₂L′ [in general, H₂L′; in detail, H₂L¹ = 5-methyl-2-phenyl-4-(2-phenyl-1-(2-(4-(trifluoromethyl)phenyl)hydrazineyl)ethyl)-2,4-dihydro-3H-pyrazol-3-one, H₂L² = (Z)-5-methyl-2-phenyl-4-(2-phenyl-1-(2-(pyridin-2-yl)hydrazineyl)ethylidene)-2,4-dihydro-3H-pyrazol-3-one] were reacted with Zn(II) and Cu(II) acceptors affording the complexes [Zn(HL¹)₂(MeOH)₂], [Cu(HL¹)₂], and [M(HL²)₂] (M = Cu or Zn). X-ray and DFT studies showed the free proligands to exist in the N–H,N–H tautomeric form and that in [Zn(HL¹)₂(MeOH)₂], zinc is six-coordinated by the N,O-chelated (HL¹) ligand and other two oxygen atoms of coordinated methanol molecules, while [Cu(HL¹)₂] adopts a square planar geometry with the two (HL¹) ligands in anti-conformation. Finally, the [M(HL²)₂] complexes are octahedral with the two (HL²) ligands acting as κ-O,N,N-donors in planar conformation. Both the proligands and metal complexes were tested against the parasite Trypanosoma brucei and Balb3T3 cells. The Zn(II) complexes were found to be very powerful, more than the starting proligands, while maintaining a good safety level. In detail, H₂L¹ and its Zn(II) complex have high selective index (55 and >100, respectively) against T. brucei compared to the mammalian Balb/3T3 reference cells. These results encouraged the researchers to investigate the mechanism of action of these compounds that have no structural relations with the already known drugs used against T. brucei. Interestingly, the analysis of NTP and dNTP pools in T. brucei treated by H₂L¹ and its Zn(II) complex showed that the drugs had a strong impact on the CTP pools, making it likely that CTP synthetase is the targeted enzyme.

New Zn(II) and Cu(II) complexes with pyrazolone-based hydrazone ligands display different structural features. The Zn(II) complexes show strong efficiency against the parasite Trypanosoma brucei, while maintaining a good safety level. They strongly impact the CTP pools, indicating that CTP synthetase is the targeted enzyme.

Pyrazolone structural motif in medicinal chemistry: Retrospect and prospect

The pyrazolone structural motif is a critical element of drugs aimed at different biological end-points. Medicinal chemistry researches have synthesized drug-like pyrazolone candidates with several medicinal features including antimicrobial, antitumor, CNS (central nervous system) effect, anti-inflammatory activities and so on. Meanwhile, SAR (Structure-Activity Relationship) investigations have drawn attentions among medicinal chemists, along with a plenty of analogues have been derived for multiple targets. In this review, we comprehensively summarize the biological activity and SAR for pyrazolone analogues, wishing to give an overall retrospect and prospect on the pyrazolone derivatives.

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The pyrazolone structural motif is a critical element of drugs aimed at different biological end-points.

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The pyrazolone analogues have been carried out to drug-like candidates with broad range of medicinal properties.

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This review wishes to give an overall retrospect and prospect on the pyrazolone derivatives.

A twofold interpenetrating three-dimensional heterometallic metal–organic framework with pcu topology based on 2-methylbiphenyl-4,4′-dicarboxylic acid

The 2-methylbiphenyl-4,4′-dicarboxylate (mbpdc2−) ligand has versatile coordination modes and can be used to construct multinuclear structures. Despite this, reports of the synthesis of coordination complexes involving this ligand are scarce. The title compound, poly[[triaquadi-μ3-hydroxido-hexakis(μ4-2-methylbiphenyl-4,4′-dicarboxylato)calcium(II)hexazinc(II)] monohydrate], {[CaZn6(C15H10O4)6(OH)2(H2O)3]·H2O} n , has been prepared by the hydrothermal assembly of Zn(NO3)2·6H2O, CaCl2 and 2-methylbiphenyl-4,4′-dicarboxylic acid. Two ZnII atoms adopt a four-coordinated distorted tetrahedral geometry by bonding to three O atoms from three different 2-methylbiphenyl-4,4′-dicarboxylate (mbpdc2−) dianionic ligands and one bridging hydroxide O atom. For the remaining ZnII atom, a five-coordinate environment is completed half the time by one carboxylate O atom, and then the same carboxylate O atom and an aqua O atom are present the other half of the time, giving a six-coordinate environment. The CaII atom is coordinated by six O atoms to give an octahedral coordination geometry. The supramolecular secondary building unit (SBU) is a hamburger-like heptanuclear unit (Zn6CaO30) and these units are interconnected through mbpdc2− carboxylate groups to generate a three-dimensional framework with the pcu topology. The single net leaves voids that are filled by mutual interpenetration of an independent equivalent framework in a twofold interpenetrating architecture. The title compound shows thermal stability up to 673 K. The excitation and luminescence data showed the emission of a bright-blue fluorescence.

Screening the DNA interaction ability and antimicrobial activity of a few novel bioactive complexes tethering N-((2-aminophenyl)(phenyl)methylene)-4-nitroaniline

Few novel transition metal complexes having N-((2-aminophenyl)(phenyl)methylene)-4-nitroaniline were synthesized and characterized by elemental analyses, IR, (1)H and (13)C NMR, electronic, EPR and mass spectra, conductivity and magnetic susceptibility measurements. All the metal complexes adopted square planar geometrical arrangements. The DNA-binding properties of the metal(II) complexes have been investigated by electronic absorption, fluorescence, CD spectra, cyclic voltammetry, differential pulse voltammogram and viscosity measurements. The results obtained indicate that these complexes bind to DNA via an intercalation binding mode. DNA cleavage activities indicate that the metal complexes exhibit greater activity than the ligand. The antimicrobial screening reveals that all the metal complexes exhibit better activity than the free ligand.

Crystal structure of [1-(3-chloro-phen-yl)-5-hy-droxy-3-methyl-1H-pyrazol-4-yl](p-tol-yl)methanone

In the title compound C₁₈H₁₅ClN₂O₂, the dihedral angles between the central pyrazole ring and the pendant chloro­benzene and p-tolyl rings are 17.68 (10) and 51.26 (12)°, respectively. An intra­molecular O—H⋯O hydrogen bond is observed, which closes an S(6) ring.

Copper(ii) complexes of salicylaldehydes and 2-hydroxyphenones: synthesis, structure, thermal decomposition study and interaction with calf-thymus DNA and albumins

The characterized copper(ii) complexes with substituted salicylaldehydes and 2-hydroxyphenones exhibit enhanced affinity for DNA and albumins in comparison to free ligands.

Crystal structure of (4Z)-1-(3,4-di-chloro-phen-yl)-4-[hy-droxy(4-methyl-phen-yl)methyl-idene]-3-methyl-4,5-di-hydro-1H-pyrazol-5-one

The title compound, C₁₈H₁₄Cl₂N₂O₂, crystallizes with two mol­ecules, A and B, in the asymmetric unit. In mol­ecule A, the dihedral angles between the central pyrazole ring and pendant di­chloro­benzene and p-tolyl rings are 2.18 (16) and 46.78 (16)°, respectively. In mol­ecule B, the equivalent angles are 27.45 (16) and 40.45 (18)°, respectively. Each mol­ecule features an intra­molecular O—H⋯O hydrogen bond, which closes an S(6) ring and mol­ecule A also features a C—H⋯O inter­action. In the crystal, weak C—H⋯π interactions and aromatic π–π stacking [shortest centroid–centroid separation = 3.707 (2) Å] generate a three-dimensional network.

Crystal structure of (Z)-1-(3,4-dichlorophenyl)-3-methyl-4-[(naphthalen-1-yl-amino)(p-tolyl)methylidene]-1H-pyrazol-5(4H)-one

The title Schiff base compound, C28H21Cl2N3O, was synthesized by the condensation of 1-(3,4-di-chloro-phen-yl)-3-methyl-4-(4-methyl-benzo-yl)-1H-pyrazol-5(4H)-one with 1-aminona-phthalene. The p-tolyl ring is normal to the pyrazole ring, with a dihedral angle of 88.02 (14)°, and inclined to the naphthalene ring system by 78.60 (12)°. The pyrazole ring is inclined to the naphthalene ring system and the di-chloro-substituted benzene ring by 63.30 (12) and 11.03 (13)°, respectively. The amino group and carbonyl oxygen atom are involved in an intra-molecular N-H⋯O hydrogen bond enclosing an S(6) ring motif. There is also a short C-H⋯O contact involving the carbonyl O atom and the adjacent benzene ring. In the crystal, mol-ecules are linked by C-H⋯π inter-actions, forming a three-dimensional structure.

A comparative study of experimental and theoretical results of conformations of oxovanadium(IV) complexes with 4-acyl pyrazolone ligands using DFT method

The optimized structures and electronic properties of the oxovanadium(IV) complexes containing 4-acyl pyrazolone ligands were calculated using density functional theory. The total energies of both the complexes were calculated e.g. syn and anti conformation of complex 1 and complex 2 with and without solvent. The calculated total energy for syn conformation was -10.162 keV, while total energy for anti conformation was -10.155 keV. Similarly, the calculated total energy for complex 2 with solvent was obtained -10.793 keV, while total energy for complex 2 without solvent was -10.158 keV. The total energy calculation shows that syn conformation is more stable in complex 1, while complex 2 is more stable in twisted geometry with solvent. In order to investigate the electronic properties of ligands and complexes, quantum chemical parameters, such as the highest occupied molecular orbital energy (HOMO), the lowest unoccupied molecular orbital energy (LUMO), and energy gap were calculated. The theoretically calculated data of the complexes are in good agreement with the data obtained by the single-crystal X-ray diffraction analysis.