Ligand HL Research Articles

An investigation of two heterobimetallic [Cu(II)2Ln(III)] (Ln = La and Ce) complexes of a more flexible bis(salamo)‐type ligand

Two heterobimetallic [Cu(II)2Ln(III)] (Ln = La and Ce) complexes composed of flexible bis(salamo)‐type ligand H4L with Cu(II) and Ln(III) atoms, [Cu2La(L)(ƞ2-NO3)3]·EtOH (1) and [Cu2Ce(L)(ƞ2-NO3)3]·EtOH (2) have been successfully synthesized, and characterized by IR spectra, elemental analyses, UV–Vis spectroscopy, the crystal structures of the complexes 1 and 2 were determined by single-crystal X-ray diffraction analyses. Each Cu(II) atom of the complexes 1 and 2 is located in the N2O2-donor of the completely deprotonated (L)4− unit, so that the two Cu(II) atoms have tetra-coordinated slightly distorted square planar geometries, while the Ln(III) (La or Ce) atom is located in the O5 cavity of the ligand (L)4− unit. At the same time, there are six oxygen atoms from three bidentate nitrate groups coordinated with the Ln(III) (La or Ce) atom, resulting in the formation of an eleven-coordinated augmented sphenocorona J87. In addition, DFT calculations and Hirshfeld surfaces analyses are performed and fluorescence properties are evaluated.

Controlled synthesis, structure and luminescent property of a 3D layered–pillared zinc(II) coordination polymer based on a newly designed ligand

Continuing our previous strategy for construction of layered–pillared coordination polymer, in this paper, a new O–thiocarbamate–containing ligand H2L (5–[(dimethylamino)thioxomethoxy]–1,3–benzenedicarboxylic acid) has been designed and synthesized to construct a zinc(II)–based metal organic framework, namely [ZnL(4,4′–bpy)]n (1) (4,4′–bpy = 4,4′–bipyridine). Single crystal X–ray diffraction analysis of 1 reveals that the metal ions are bridged by L2– ligands to generate a two–dimensional layer, and the layers are further pillared by 4,4′–bpy to form a three–dimensional framework with a pcu topology. Furthermore, the solid state photoluminescent studies reveal that both H2L and polymer 1 display emission bands at 400 nm upon excitation at 325 nm. The average emission life time is 4.27 µs.

Competent DNA binder pentagonal bipyramidal Fe(II) complex executed as a proficient catalyst for primary carbamates production from alcohols and urea

The iron (II) complex, [Fe(H2L)(H2O)2](ClO4)2(H2O) (1) of Schiff base ligand H2L [5-Methyl-1-H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide] was prepared and structurally determined by X-ray crystal analysis. The complex 1 is being hepta-coordinated mononuclear system that adopts pentagonal bipyramidal geometry. Moreover, the calf thymus DNA (CT-DNA) interaction with 1 was carried out by proper bio-physical methods. The complex 1 was observed to interact with CT-DNA by intercalation binding mode and the binding constant of this interaction was calculated as (1.5 ± 0.06) × 106 M−1 and that was obtained from fluorimetric spectral titration. Again the complex 1 is very much effective in the catalytic reaction of primary carbamate synthesis. In this procedure alcohols and eco-friendly sustainable carbonylation source urea were used for the synthesis of desired product. Both aromatic alcohols as well as aliphatic alcohols were efficiently proceeded through the catalytic reaction and produced medium to high yield (up to 94%) of carbamate products under mild reaction conditions. The catalytic mechanism was also supported by DFT studies.

Investigation of syntheses, structures, theoretical calculations, and fluorescence properties of two N3O-donor half-salamo-type Cu(II) complexes

The coordination behaviors of asymmetric quinoline-decorated half-salamo-type ligand HL1 with Cu(NO3)2·3H2O and Cu(OAc)2·H2O were studied. Two Cu(II) complexes, [Cu(L1)(NO3)]·CH3CH2OH (1) and [Cu2(L2)2] (2), were isolated and characterized by X-ray crystallography, FTIR, UV–vis, and fluorescence spectroscopies. Structural analyses showed that 1 is a mononuclear species, whereas 2 is a binuclear entity. Spontaneous cleavage along the oxime N-O bond close to quinoline ring of the ligand HL1 occurred upon reaction with Cu(OAc)2·H2O, yielding an unexpected complex 2. Moreover, DFT theoretical calculations and Hirshfeld surfaces analyses of the ligand HL1 and its corresponding Cu(II) complexes were investigated in detail.

Solvent-driven self-assembly of two novel di- and tetra-nuclear Cu(II) bis(salamo)-based complexes

Two novel di- and tetra-nuclear Cu(II) complexes, [Cu2(HL)Cl2(MeOH)]·MeOH (1) and [Cu4(HL)2Cl2(μ2-Cl)2]·4EtOH·H2O (2) (where H3L= bis(salamo)-based ligand) have been synthesized, and structurally characterized by elemental analysis, infrared and electronic absorption spectroscopy. The molecular structures of complexes 1 and 2 were defined by using single crystal X-ray diffraction experiment. The structural results indicated that complexes 1 and 2 have a close comparable [Cu2(HL)Cl2] unit in the unit cell where the ligand acts as a two-compartmental species chelating the metal ions Cu1 and Cu2. However, in complex 2, the [Cu2(HL)Cl2] complexes are paired in a centrosymmetric fashion to form a tetra-nuclear arrangement, connected by μ2-bridging chlorides. The observed different nuclearity is likely induced by the different solvent molecules used in the syntheses, methanol and ethanol in complexes 1 and 2, respectively. A methanol molecule participates in coordination of complex 1, while ethanol species in complex 2 is rather distant from one of the Cu(II) ions (ca 2.82 Å). The molecular frontier orbitals HOMO and LUMO of the complexes were analyzed by DFT calculations, and the results showed that the energy gaps of complexes 1 and 2 are particularly small compared to H3L, which may be caused by the combination of the orbitals of the central atoms and the donor atoms. The reaction sites of the ligand H3L with the metal Cu(II) were analyzed by ESP studies, and the results showed that the experiments were in agreement with the theory. Finally, Hirshfeld surfaces analyses were performed to quantitatively show various weak interactions of complexes 1 and 2.

Synthesis, Structural Studies and Antimicrobial Evaluation of Nickel(II) Bis-Complex of Schiff Base of S-Benzyldithiocarbazate

A tridentate nitrogen-oxygen-sulfur (NOS) S-benzyl(2-oxoindolin-3-ylidene)dithiocarbazate, HSBISA (HL1) ligand was synthesized via a condensation reaction between S-benzylditihocarbazate (SBDTC) and isatin. The produced ligand was reacted with nickel(II) acetate salt in 1:2 (metal:ligand) ratio to yield a brown Ni(SBISA)2 complex (2) (SBISA = monoanionic form of HL1). Characterization of HL1 and its Ni(II) complex was performed via elemental analysis, FT-IR, ICP-AES, UV-Vis spectroscopy and mass spectrometry, along with molar conductivity and magnetic susceptibility measurement. Slow evaporation of 2 from DMSO at room temperature led to a structure crystallizing in the monoclinic P21/a space group with a = 18.6860(3), b = 11.3037(2), c = 19.8993(3), b = 112.1897(10), V = 3891.86(11) Å3, wR2 (all data) = 0.0407 and R1 = 0.0386 for data with I > 2σ(I). The nickel(II) metal center is ligated by doubly-deprotonated NOS monoanionic tridentate HL1 ligands forming a neural distorted octahedral Ni(SBISA)2×2DMSO (2a) complex. The antimicrobial assays of both compounds were performed on selected pathogenic bacteria and fungi strains. HIGHLIGHTS Octahedral Ni(II) complex was synthesized using acetate salt Compound was characterized via physico-chemical analyses Structural studies were resolved via single crystal X-ray diffraction Compound 2a crystallized in a monoclinic system (P21/a space group) with cell parameters a = 18.6860 (3), b = 11.3037 (2), c = 19.8993(3), b = 112.1897 (10), V = 3891.86 (11) Å3, wR2 (all data) = 0.0407 and R1 = 0.0386 for data with I > 2σ(I) Compound was evaluated for its antimicrobial activity GRAPHICAL ABSTRACT

Selective Turn-On Fluorescence Sensing of Cyanide Using the Pyridoxal Platform of a Ni(II) Complex

Cyanide is a very toxic pollutant to aquatic life and the environment. Analytical methods for the quantitative assay of cyanide, which are rapid, sensitive (low limit of detection), and cost-effective, are in great demand. Colorimetric and fluorometric methods are ideally suited for this purpose. In this report, we describe a Ni(II) complex containing a pyridoxal platform for the rapid and sensitive fluorometric estimation of cyanide. The square-planar Ni(II) complex, [Ni(L)(N3)]·3H2O, where the ligand LH = 4-[(2-dimethylamino-ethylimino)-methyl]-5-hydroxymtheyl-2-methyl-pyridin-3-ol, a Schiff base formed between pyridoxal and (2-dimethylamino)ethyl amine, was synthesized and characterized by various spectroscopic techniques as well as by single-crystal X-ray structure determination. The complex was found to selectively bind CN- in the presence of other biologically important anions such as F-, Cl-, Br-, I-, OAc-, S2-, NO3 -, PO4 3-, SO4 2-, and H2PO4 - in tris-HCl/NaCl buffer [pH = 7.4], and it can be monitored by fluorescence turn-on or by UV-visible spectroscopy. The binding constant of the complex with CN- was estimated to be 2.046 × 1014 M-2 and the limit of detection (LOD) was 9 nM, the LOD being considerably lower than the maximum permissible level of cyanide ions (1.9 μM) in drinking water, as recognized by the World Health Organization (WHO). The effects of pH and temperature on the sensing are also investigated. The Ni(II) complex is also found to bind to calf-thymus DNA very strongly, and the apparent binding constant (K app) was determined to be 1.33 × 107 M-1 by the fluorescence quenching of the ethidium bromide-DNA adduct by the complex.

Synthesis and characterization of thiosemicarbazone metal complexes: Crystal structure, and antiproliferation activity against breast (MCF7) and lung (A549) cancers

Thiosemicarbazone compound has pronounced anticancer activity, which increases by metal ions presence. New Ni(II), Cu(II), Pd(II), and Pt(II) complexes synthesized from 2-(2,3-dihydroxy benzylidene)-N-ethylhydrazine-1-carbothioamide ligand H3L and had been characterized via NMR, GC–MS, FTIR, CHNS, UV–vis, TGA, magnetic susceptibility measurements, and molar electric conductivity. X‐ray crystallographic data and the refinement structure of thiosemicarbazide ligand indicated a clear light colorless block with the formula C10H13N3O2S, which belongs to a monoclinic system with P1 21/ c1 space group and adopts orthorhombic crystal with a = 5.1509(3) Å; b = 10.2856(6) Å; c = 11.3261(6) Å. The ligand and the metal complexes were also tested for antiproliferation activity against the MCF7 breast and A549 lung cancer cell lines. The data showed that Ni(II), Cu(II), Pd(II), and Pt(II) complexes had potent antiproliferation activity at the micromolar level. Pt(II) complex with square planar geometry exhibits the highest antiproliferation activity, while Ni(II) complex with distorted octahedral geometry showed the lowest antiproliferation activity in both cell lines.

Thiosemicarbazones and Derived Antimony Complexes: Synthesis, Structural Analysis, and In Vitro Evaluation against Bacterial, Fungal, and Cancer Cells

Two antimony complexes {[Sb(L1)Cl2] C1 and [Sb(L2)Cl2] C2} with the thiosemicarbazone ligands {HL1 = 4-(2,4-dimethylphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were introduced. The structures were elucidated on the basis of a CHNS analysis, spectroscopic techniques (UV-Vis and FT-IR), and DMF solution electrical conductivities. Single crystal X-ray diffraction analysis of complex C1 assigned the complex pseudo-octahedral geometry and triclinic P-1 space group. Only the ligand HL1 and its derived complex C1 displayed antifungal activities against Candida albicans and this activity was enhanced from 10 mm to 21 mm for the respective complex, which is the same activity given by the drug “Amphotericin B”. The ligands HL1 and HL2 gave inhibitions, respectively, of 14 and 10 mm against Staphylococcus aureus and 15 and 10 mm against Escherichia coli; however, complexes C1 and C2 increased these inhibitions to 36 and 32 mm against Staphylococcus aureus and 35 and 31 mm against Escherichia coli exceeding the activities given by the ampicillin standard (i.e., 21 mm against Staphylococcus aureus and 25 mm against Escherichia coli). Against MCF-7 human breast cancer cells, the IC50 values of HL1 (68.9 μM) and HL2 (145.4 μM) were notably enhanced to the values of 34.7 and 37.4 μM for both complexes, respectively. Further, the complexes induced less toxicity in normal BHK cells (HL1 (126.6 μM), HL2 (110.6 μM), C1 (>210.1 μM), and C2 (160.6 μM)). As a comparison, doxorubicin gave an IC50 value of 9.66 μM against MCF-7 cells and 36.42 μM against BHK cells.

Modulating the Inclusive and Coordinating Ability of Thiacalix[4]arene and Its Antenna Effect on Yb3-Luminescence via Upper-Rim Substitution.

The present work introduces the series of thiacalix[4]arenes (H4L) bearing different upper-rim substituents (R = H, Br, NO2) for rational design of ligands providing an antenna-effect on the NIR Yb3+-centered luminescence of their Yb3+ complexes. The unusual inclusive self-assembly of H3L− (Br) through Br…π interactions is revealed through single-crystal XRD analysis. Thermodynamically favorable formation of dimeric complexes [2Yb3+:2HL3−] leads to efficient sensitizing of the Yb3+ luminescence for H4L (Br, NO2), while poor sensitizing is observed for ligand H4L (H). X-ray analysis of the single crystal separated from the basified DMF solutions of YbCl3 and H4L(NO2) has revealed the transformation of the dimeric complexes into [4Yb3+:2L4−] ones with a cubane-like cluster structure. The luminescence characteristics of the complexes in the solutions reveal the peculiar antenna effect of H4L(R = NO2), where the triplet level at 567 nm (17,637 cm−1) arisen from ILCT provides efficient sensitizing of the Yb3+ luminescence.

Utilization of diamagnetic Zn(II) ion to boost the anisotropic nature of Ln(III) ion in heterodinuclear Zn(II)–Ln(III) single‐molecule magnets

A series of dimetallic ZnII–LnIII compounds of general formulae [LnZn(L)3(NO3)2]·2CH3OH (LnIII = DyIII (1), TbIII (2), GdIII(3)) was prepared by stepwise reaction of compartmental ligand LH = ((E)‐2‐((pyridin‐2‐ylmethylene)amino)phenol) with Ln (NO3)3·xH2O and Zn (NO3)2·xH2O in the presence of triethylamine as base. The single crystal XRD analysis indicated that both metallic ions are connected to each other through phenolic oxygen atom from fully deprotonated ligand. Based on the SHAPE analysis, the DyIII ion has nine coordination numbers with distorted spherical capped square antiprism geometry, while the ZnII ion has six coordination numbers with distorted octahedral geometry. DC magnetic studies reveal the existence of antiferromagnetic interaction between the ZnII and LnIII metal centers. AC magnetic studies reveal that the complex 1 show field‐induced single‐molecule magnet (SMM) properties with an effective energy barrier of 155 K under an applied dc field of 0.1 T, whereas complex 2 does not show SMM behavior. Furthermore, we conducted DFT and ab initio CASSCF + RASSI‐SO calculations to probe the single‐ion properties of Ln(III) ions and to understand the role of the diamagnetic ZnII ion in the magnetization relaxation in order to interpret the experimental observations. Ab initio calculations predict that the gz values are strongly axial in nature in the ground state of Dy(III) ion in complex 1 and that allows the magnetic relaxation to occur via excited states with a Ucal of 380.8 K. DFT calculations discovered that the presence of the diamagnetic Zn(II) ion causes greater negative charges on the bridging oxygen atoms, which enhances the anisotropy of Dy(III) ion and thus reduces the quantum tunneling of magnetization (QTM) effects, and helps to achieve better SMM features for 1.

Treatment Activity of Ho(III)-Based Coordination Polymer on Liver Cancer by the Inhibition of Vascular Endothelial Growth Factor Signaling Pathway Activity

A new 0D dinuclear coordination polymer [Ho2(L)6(phen)2] (1) was hydrothermally synthesized based on HoCl3·6H2O, organic ligand HL = 3-hydroxybenzoic acid, and the auxiliary ligand phen = 1,10-phenanthroline (L− is the fully deprotonated organic ligand), and full characterization of the structure was performed via the X-ray single-crystal diffraction data. Once this newly synthesized novel compound was achieved, the way it acted inside the liver cancer was examined, and the corresponding mechanism was determined. First, the Cell Counting Kit-8 (CCK-8) method was conducted to analyze the compound activity after the treatment of liver cancer cells. In addition, real-time reverse-transcription polymerase chain reaction (RT-PCR) method was used to examine the in-cell vascular endothelial growth factor (VEGF) signaling pathway activity. The molecular docking simulation showed that the carboxyl and phenol groups contained active binding receptor sites, indicating that Ho complex has excellent biological activity.

Experimental and Computational Studies on the Interaction of a Dansyl-Based Fluorescent Schiff Base Ligand with Cu2+ Ions and CuO NPs.

We studied the interaction of Cu2+ ions and CuO nanoparticles with the fluorescent Schiff base ligand H3L, which derives from the condensation of 4-formyl-3-hydroxybenzoic acid with N-(2-aminobenzyl)-5-(dimethylamino)naphthalene-1-sulfonamide (DsA). A detailed assignment of the most significant bands of the electronic and infrared spectra of H3L and DsA was performed using DFT methods, based on both crystal structures. The affinity of H3L to react with Cu2+ ions in solution (KB = 9.01 103 L mol−1) is similar to that found for the Cu2+ ions present on the surface of CuO NPs (KB = 9.84 103 L mol−1). Fluorescence spectroscopic measurements suggest five binding sites for H3L on the surface of the CuO NPs used. The µ-XRF analysis indicates that a polycrystalline sample of CuO-H3L NPs contains 15:1 Cu:S molar ratio (CuO:H3L). ATR-FTIR spectroscopy, supported by DFT calculations, showed that the HL2− (as a phenolate and sulfonamide anion) is coordinated to superficial Cu2+ ions of the CuO NPs through their azomethine, sulphonamide, and phenolic groups. A solution of H3L (126 ppb) shows sensitive responses to CuO NPs, with a limit of detection (LOD) of 330 ppb. The working range for detection of CuO NPs with [H3L] = 126 ppb was 1.1–9.5 ppm. Common metal ions in water, such as Na+, K+, Mg2+, Ca2+, Fe3+, and Al3+ species, do not interfere significantly with the detection of CuO NPs.

Detecting CdSe Nanomaterials with a Fluorescent Schiff Base Ligand

We investigated the easily synthesized ligand H3L as a fluorescent chemosensor for the detection of CdSe nanoparticles (CdSe NPs) and L-cysteine-capped CdSe quantum dots (CdSe-Cys QDs) in ethanol–water samples. A drastic quenching of the fluorescence emission of H3L at 510 nm occurred, as a result of the addition of CdSe NPs and CdSe-Cys QDs. A solution of H3L (1.26 ppb) showed sensitive responses to both CdSe NPs and CdSe-Cys QDs, with limits of detection (LOD) as low as 40 and 62 ppb, respectively. Moreover, using a smartphone color recognizer application, the fluorescence intensity response of H3L-modified cellulose paper to CdSe-Cys QDs was recorded on a red channel (R), which allowed us to detect CdSe-Cys QDs with LOD = 15 ppb. Interference of some common metal nanomaterials (NMs), as well as metal ions, in the determination of CdSe NMs in solution was studied. The affinity of H3L to CdSe NPs and CdSe-Cys QDs was spectroscopically determined. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), micro-X-ray fluorescence (µ-XRF), 1H-NMR, attenuated total reflection infrared spectroscopy (ATR-IR), and density functional theory (DFT) were also used to investigate the interaction of H3L with CdSe NMs.

New wheel-shaped Ln6 clusters for conversion of CO2 and magnetic properties

A series of novel hexanuclear lanthanide clusters, namely, [Ln6(HL)6(NO3)6]·3CH3CN (Ln = Gd(1), Tb(2), Dy(3) and Er(4)) was assembled using a multidentate ligand H3L (trolamine). The clusters 1–4 show a wheel-shaped Ln6 topology with the approximate diameter and thickness of 1.5 and 0.7 nm, respectively. All of them show high thermal stability. In the aspect of the catalytic capacities for the cycloaddition reactions of CO2 and epoxide, the reaction conditions, the substrate scope, and possible catalytic mechanism were investigated. The highest yield for clusters 1–4 is up to 99% at 333 K for 12 h. In particular, cluster 1 can be reused at least three times with no obvious loss of catalytic performance and keep the integrity of the crystal structure. Magnetic investigations reveal that cluster 1 exhibits a relatively large magnetocaloric effect with −ΔSm = 41.43 J/(kg⋅K) (T = 3.0 K, 7.0 T); while cluster 3 displays slow magnetic relaxation behavior under zero dc field with Ueff = 0.51 K and τ0 = 2.54 × 10−5 s.

Structural, theoretical and optical investigations of two lateral twisting trinuclear Co(II) and Ni(II) salamo type complexes

Two trinuclear Co(II) and Ni(II) complexes, [{Co3(L)2(μ-OAc)2}2]·3CH2Cl2 (1) and [Ni3(L)2(μ-OAc)2(EtOH)2]·2EtOH (2) have been successfully obtained by a new nonsymmetrical salamo type ligand H2L with Co(OAc)2·4H2O and Ni(OAc)2·6H2O, respectively. Single crystal X-ray diffraction analysis revealed that complex 1 is an unsymmetric trinuclear structure, two tetradentate N2O2-donor ligand (L)2- units are coordinated to three Co(II) atoms where two terminal Co(II) atoms are penta-coordinated lateral twisting trigonal bipyramidal geometries but central Co(II) atom is hexa-coordinated lateral twisting octahedral configuration. Complex 2 is a centrosymmetrical trinuclear structure, all of the three Ni(II) atoms are hexa-coordinated lateral twisting octahedral configurations. In addition, complexes 1 and 2 have been characterized by physicochemical and spectroscopic methods. Molecular electrostatic potential analysis revealed that the phenolic oxygen atoms in the ligand H2L have nucleophilic reactions with Co(II) and Ni(II) atoms to form chemical bonds. Hirshfeld surfaces analyses showed that H···H/H···H interactions are the predominant, indicating the presence of great amount hydrogen bonds in complexes 1 and 2. IRI analyses indicated the presence of weak hydrogen bonding interactions that made complexes 1 and 2 more stable.

Trivalent Cobalt Complexes with NNS Tridentate Thiosemicarbazones: Preparation, Structural Study and Investigation of Antibacterial Activity and Cytotoxicity against Human Breast Cancer Cells

New complexes of trivalent cobalt with substituted thiosemicarbazone ligands having an NNS donor system {HL1 = 4-(4-nitrophenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were synthesized via the in situ oxidation of divalent cobalt chloride accompanying its addition to the ligands. The complexes C1 and C2 were characterized via elemental (CHNS) analysis and 1H NMR, FT-IR and UV-Vis. spectroscopic data. Further, conductometric studies on the DMF solutions of the complexes indicated their 1:1 nature, and their diamagnetism revealed the low-spin trivalent oxidation state of the cobalt in the complexes. The X-ray diffraction analysis of complex C1 indicated that it crystallizes in the triclinic space group P-1. The metal exhibits an octahedral environment built by two anionic ligands bound via pyridine nitrogen, imine nitrogen and thiol sulfur atoms. The complex is counterbalanced by a chloride ion. In addition, two lattice water molecules were detected in the asymmetric unit of the unit cell. The ligand HL2 (20 mg/mL in DMSO) displayed inhibition zones of 10 mm against both S. aureus and E. coli, and the same concentration of the respective complex raised this activity to 15 and 12 mm against these bacterial strains, respectively. As a comparison, ampicillin inhibited these bacterial strains by 21 and 25 mm, respectively. Screening assay by HL1 on four human cancer cells revealed the most enhanced activity against the breast MCF-7 cells. The induced growth inhibitions in the MCF-7 cells by all compounds (0–100 μg/mL) have been detected. The ligands {HL1 and HL2} and complex C2 gave inhibitions with IC50 values of 52.4, 145.4 and 49.9 μM, respectively. These results are more meaningful in comparison with similar cobalt complexes, but less efficient compared with the inhibition with IC50 of 9.66 μM afforded by doxorubicin. In addition, doxorubicin, HL1 and HL2 induced cytotoxicity towards healthy BHK cells with IC50 values of 36.42, 54.8 and 110.6 μM, but surviving fractions of 66.1% and 62.7% of these cells were detected corresponding to a concentration of 100 μg/mL of the complexes (136.8 μM of C1 and 131.4 μM of C2).

Hydrazone bimetallic complex: synthesis, characterization, in silico and biological evaluation targeting breast and lung cancer cells’ G-quadruplex DNA

Manganese complex of (N'1E,N'3E)-N'1,N'3-bis(2-hydroxybenzylidene)isophthalo-hydrazide [H4L] was designed, spectroscopically analyzed, and confirmed via GC-MS, FTIR, CHNS, UV-VIS, magnetic susceptibility measurements, and molar electric conductivity. The data confirmed the formation of ligand H4L and [Mn2(H2L)Cl]Cl.2H2O complex. Ligand H4L acts as a bi-negative hexadentate and tetra-negative hexadentate coordinating through two amide carbonyl, two azomethine, and two deprotonated OH groups. The magnetic and spectral data proposed a square-planar and a tetrahedral structure. The TGA data confirmed the final metal oxide form for the Mn ligand complex. Additionally, an in-vitro assessment of the ligand H4L confirmed its ability to control cancer cell proliferation in both breast (MCF7) and lung (A549) cancer cell lines while the Mn ligand complex possessed an anticancer effect in both cancer cells at the nano-molar level. Further, the in silico data showed four hydrogen bond interactions of the ligand with G-quadruplex DNA. This strengthens our hypothesis that the hydrazone complex acts as an anticancer agent by targeting the G-quadruplex DNA.

Synthesis, Characterization, Antioxidant and Antibacterial Activities of Six Metal Complexes Based Tetradentate Salen Type Bis-Schiff Base

Considering the importance of metal complexes in the development of medicinal chemistry, a series of transition metal complexes of Co(II), Fe(II), Zn(II), Cu(II), and Ni(II) has been synthesized from N,N'-bis(salicylidene)-2,2-dimethyl-1,3-diaminopropane H2L Schiff base ligand. The reaction of the H2L with the selected metal ions led to tetrahedral and octahedral coordinated complexes. The structural features of the obtained metal complexes were determined using analytical techniques such as FT-IR, NMR, UV-Vis, X-ray powder diffraction, mass spectrometry, and Thermogravimetry–differential thermal (TGA/DTA) analysis. The measured conductance for obtained compounds has shown the electrolytic behavior of all obtained complexes. The synthesized ligand and corresponding complexes were screened for their antioxidant and antibacterial activities. Indeed, Co(II) and Fe(II) complexes have shown excellent antioxidant activities for DPPH radical scavenging and FRAP assays, respectively. The results obtained from the disc diffusion assay showed that Co(II), Fe(II), Zn(II), and Cu(II) complexes had displayed promising antibacterial activity against Escherichia coli and Staphylococcus aureus, while no effect has been observed on both strains for ligand H2L and its corresponding Ni(II) complex.

Fluorescence, cyclic voltammetric, computational, and spectroscopic studies of Mn(II), Co(II), Pd(II), Zn(II) and Cd(II) complexes of salen ligand and their biological applications

2,2′-((1E,1′E)-(ethane-1,2-diylbis(azanylylidiene))bis(methanylylidene))diphenol (H2L) ligand and its Mn(II), Co(II), Pd(II) Zn(II) and Cd(II) chelates have been isolated and characterized by conventional and spectroscopic techniques including FTIR spectrum, 1HNMR , 13CNMR , powder X-ray diffraction [PXRD], UV–visible, mass spectroscopy besides elemental analyses, and magnetic susceptibility measurements. The DMOL3 tool in the material studio package was also used to optimize the structures. The ligand behaves as binegative N2O2 tetradentate in Pd(II) and Zn(II) complex, neutral N2 bidentate in Mn(II), Co(II) and Cd(II)-complexes. Horowitz–Metzger and Coats–Redfern approaches were used to estimate the various kinetic and thermodynamic parameters. Zeta Potentials for the H2L ligand and its Pd(II), Cd(II) and Co(II) complexes in ethanol as a dispersive medium were measured. Ligand and its complexes were tested for their biological potency as anti-bacterial activity against gram (-) E. coli, P. aeruginosa, and gram (+) B. subtilis, S. aureus bacteria as well as antifungal activity against C. albicans. The antioxidant potentials of the isolated compounds were also screened by using DPPH scavenging methods. The isolated compounds were examined for cytotoxic activity using the MTT assay on MDA-MB-231 and HepG2 cell lines, and the results were verified using molecular docking simulations.