Tridentate Schiff Base Research Articles

An Ammonium Cation Included Dinuclear Cd(II) Complex and A Face-Shared Octahedral Dinuclear Cd(II) Complex with N2O Donor Tridentate Schiff base Ligand

One face-shared octahedral Cd(II) complex and one ammonium cation included Cd(II) complex have been examined with the N2O donor monoanionic Schiff-base ligand 4-methyl-2,6-bis(((phenylmethyl)imino)methyl)phenol (HL) having a central phenoxide unit. The configuration of the cadmium coordination geometries is responsible for varying modes of ligand binding and structures. The gas phase geometry of complex 1 has been optimized by density functional theory. In CH3OH, the reaction between HL and Cd(NO3)2·4H2O in the presence of triethylamine produces a tris-L clipped face-shared octahedral dinuclear complex [Cd2(μ-L)3]·(OH) (1). Use of Cd(NO3)2·4H2O and NH4SCN in CH3OH in the absence of triethylamine leads to the synthesis of [Cd2(μ-L)2(μ1,1-NCS)(μ-NH4 +)(NCS)2] (2), which contains a NH4 + cation at its center. Changes in co-ligands have an ability to regulate the synthesis of these two Cd(II) complexes, effectively allowing selfassembly to be directed. Three types of bridges of Cd(OPh)3Cd and Cd(OPh)2(μ1,1-NCS)(μ- H4+)Cd in 1 and 2 are responsible for the Cd···Cd separations of 3.324 and 3.432 Å, respectively.

Explorations on the synthesis, structure, DFT, DNA binding properties and molecular docking of tridentate Schiff base Copper (II) complexes

Copper(II) Schiff base complexes of (2-Hydroxy-benzaldehyde)-amino acid have been synthesized and characterized. The complexes' single-crystal X-ray structures were studied, and it was discovered that the 4,4-bipyridine functions as a bidentate bridging ligand connecting two Cu(II) ions. In order to assemble the complicated components into a three-dimensional chain structure and arrange the 4,4-bipyridine molecules into parallel sheets, intermolecular hydrogen bonds are essential. A robust intermolecular hydrogen bond network including water oxygen atoms strengthens the connection between water molecules and phenolate oxygen atoms from the ligand, which is produced from salicylaldehyde. The complexes' interaction with DNA was investigated by UV–Visible, fluorescence and CD spectrophotometric methods, which indicate that the complexes favourably bind to the groove in the DNA. The DNA binding affinity was confirmed by molecular docking. Additionally, DFT calculations were used to determine the stable geometry for these complexes. A thorough understanding of the interactions of these synthesized complexes was achieved through an intensive molecular docking research. These findings show that the complexes have a high affinity for DNA binding and considerable groove binding. Notably, Complex 1 showed a greater affinity for DNA than Complex 2.

Thiocyanato and Schiff base coordinated mono/di-nuclear Ni(II) complexes: Syntheses, crystal structures and protein binding

Two Ni(II) complexes, [Ni2(L1)2(SCN)2(dmf)2] (1) and [Ni(L2)(SCN)] (2) [where HL1 = 2-ethoxy-6-[(2-phenylamino-ethylimino)-methyl]-phenol, HL2 = 2-[(2-pyrrolidin-1-yl-ethylimino)-methyl]-phenol, dmf = N,N-dimethylformamide], have been synthesized and characterized by single crystal X-ray diffraction, IR and mass spectroscopic studies. In the centrosymmetric complex 1, two Ni(L1) fragments are connected via µ2-oxo bridges and the metals complete the octahedral coordination with one thiocyanate and one dmf solvent molecule. In complex 2, the Ni(II) ion is coordinated by the tridentate Schiff base and a thiocyanate in a square planar environment. Both the complexes form 1D supra-molecular network through CH…π interactions and complex 2 also via H-bonding. The interaction of complexes with serum albumins was investigated using UV–Vis absorption and fluorescence spectroscopic techniques.

Synthesis, Structural Characterisation and Biological Activity; New Metal Complexes Derived from Semicarbazone Ligand

The results of synthesizing a novel tridentate Schiff-base ligand and its metal complexes have been given. The ligand itself is described as being tridentate. The synthesis of the ligand has the following chemical formula: (E)-2-((2S)-4-(tert-butyl) -2-((S)-(phenylamino) (p-tolyl) methyl) cyclohexylidene) hydrazine -1-carboxamide was produced as a byproduct of the reaction between benzoic acid and benzoic acid between (((4-(tert-butyl)-2-((S)-(phenylamino)(p-to and (HL). The ligand was reacted with 1:1 (L:M) mole ratios of ions containing Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), which resulted in the production of title complexes. In cases where it was necessary, physicochemical techniques were utilized to characterize both the ligand and the complexes. Examples include magnetic susceptibility and conductance measurements, microanalysis of elements, nuclear magnetic resonance (1H, 13C), mass spectrometry, Fourier transform infrared (FT-IR), electronic spectra, and more. The results of these studies demonstrated that the ions Mn (II), Co (II), Cu(II), Ni(II), Zn(II), and Cd(II) can be partitioned into four-coordinate and six-coordinate complexes, respectively. In addition, the TGA was used to investigate whether or not the ligand and specific complexes were thermally stable. Several different bacterial and fungus strains were utilized to examine the ligand and its complexes for potential antibacterial activity. According to the findings, the complexes are far more effective than the free ligand in combating a wider variety of species. Keywords: Structural study; Metal complexes; Mannich -β-amino carbonyl; Thermal stability; Staphylococcus aureus (G+).

Synthesis, characterization, crystal structure, thermal and redox behaviour and antiproliferative studies of morpholine‐based two copper(II) compounds

Two novel copper(II) complexes, [Cu(L)(Cl)2](H2O) (1) and [Cu(L)(N3)2] (2), have been synthesized from a morpholine‐based N,N,N donor tridentate Schiff base ligand, (E)‐N‐(2‐morpholinoethyl)‐1‐phenyl‐1‐(pyridin‐2‐yl)methanimine (L). Ligand (L) and its stabilized complexes, 1 and 2, have been comprehensively characterized by different physical and spectroscopic techniques. Solid‐state single‐crystal X‐ray structures of both 1 and 2 have been determined. Powder X‐ray diffraction studies on the bulk samples of 1 and 2 have been executed to demonstrate that the synthesized bulk materials retain their solid‐phase purity as that exists in the single crystals. Cyclic voltammetric experiments have been done to demonstrate the redox behaviour of 1 and 2. UV–vis spectra of the copper(II) complexes with variation in time were accrued to probe that both 1 and 2 retain their stability in solution. Thermogravimetric analysis (TGA) has been performed to collate the thermal stability of 1 along with its possible thermal degradation behaviour. Room temperature magnetic moments of 1 and 2 have been determined. Cytotoxic activity of 1 and 2 has been screened against non‐small human lung cancer cell, A549.

Synthesis, Structures and Photophysical Properties of Tetra- and Hexanuclear Zinc Complexes Supported by Tridentate Schiff Base Ligands

The synthesis, structure and photophysical properties of two polynuclear zinc complexes, namely [Zn6L2(µ3-OH)2(OAc)8] (1) and [Zn4L4(µ2-OH)2](ClO4)2 (2), supported by tridentate Schiff base ligand 2,6-bis((N-benzyl)iminomethyl)-4-tert-butylphenol (HL) are presented. The synthesized compounds were investigated using ESI-MS, IR, NMR, UV-vis absorption spectroscopy, photoluminescence spectroscopy and single-crystal X-ray crystallography. The hexanuclear neutral complex 1 comprises six-, five- and four-coordinated Zn2+ ions coordinated by O and N atoms from the supporting ligand and OH- and acetate ligands. The Zn2+ ions in complex cation [Zn4L4(µ2-OH)2]2+ of 2 are all five-coordinated. The complexation of ligand HL by Zn2+ ions leads to a six-fold increase in the intensity and a large blue shift of the ligand-based 1(π-π)* emission. Other biologically relevant ions, i.e., Na+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+ and Cu2+, did not give rise to a fluorescence enhancement.

Synthesis, characterization, photocatalytic activity, DNA interaction and antimicrobial studies of some lanthanide(III) complexes with a tridentate Schiff base ligand

Lanthanide complexes of Sm(III), Nd(III), and Dy(III) with a Schiff base ligand, (potassium2-((4-hydroxy-3-methoxybenzylidene)amino)acetate, derived from condensation of 4-hydroxy-3-methoxybenzaldehyde and 2-aminoethanoic acid were synthesized. The compounds were characterized by elemental analysis, IR, UV–Vis, 1H-NMR, ESI-MS, photoluminescence spectra, thermogravimetric analysis, magnetic susceptibility, and molar conductivity measurements. No well-defined peaks were observed in X-ray diffractograms of the synthesized complexes, indicating an amorphous nature. The Schiff base ligand is tridentate and coordinated with the metal ion through phenolic oxygen, azomethine nitrogen, and carboxylic oxygen. Thermal properties of the metal complexes were studied using thermogravimetric analysis (TG/DTG) and revealed good thermal stability. The photocatalytic efficiencies of the complexes were explored using solar water-splitting. The optical band gaps (E g) were measured and found to be 2.94, 2.86, and 2.82 eV for Sm(III), Nd(III), and Dy(III) complexes, respectively. These values indicated the semi-conducting nature of the investigated complexes. At room temperature, samarium and dysprosium complexes showed characteristic luminescence of the central metal ions ascribed to the efficient transfer of energy from the Schiff base ligand to the metal center under excitation at 390 nm. The binding properties of these complexes with calf-thymus DNA (CT-DNA) have been investigated using absorption spectrophotometry and fluorescence studies. The physicochemical properties such as hydrodynamic size, zeta potential, and stability of the DNA/complexes were also investigated. DNA cleavage activities of the compounds were assayed using the Agarose gel electrophoresis method. In-vitro antimicrobial activities of the compounds were screened against selected pathogenic strains by Agar well diffusion method.

Design, spectroscopic characterization, DFT, molecular docking, and different applications: Anti-corrosion and antioxidant of novel metal complexes derived from ofloxacin-based Schiff base

A new tridentate Schiff base ligand derived from ofloxacin (oflo) with 2-aminophenol was synthesized and a series of d-transition metal complexes were prepared. The ligand and its metal complexes were investigated using elemental, spectral, and thermal studies. The molecular and electronic structure of the free ligand and its Zn(II) complex were refined theoretically, and the chemical quantum parameters were computed. SEM studies were conducted on the free ligand and its Ni(II) chelate to confirm their nanostructure. The anti-corrosive performance of HL for mild steel (MS) was employed using electrochemical frequency modulation (EFM), potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) and showed a significant efficiency as anticorrosion agent (89.71%). Molecular docking studies were carried out between the ligand and its [Zn(HL)(H2O)Cl2] complex with active sites of 3T88, 3Q8U, and 3Q7K receptors and the complex showed the strongest binding with 3T88 receptor (-31.9 kcal mol−1). The antioxidant activity of the free ligand and its metal chelates had been carried out using the standard DPPH method and the free ligand showed the highest antioxidant activity (IC50 = 10.52 µg/mL). The in vitro antibacterial activity showed that all prepared compounds were biologically active and Fe(III) complex has the highest inhibiting activity against Proteus Vulgaris Gram-negative bacteria.

Ru(II) complexes containing NOO donors of tridentate Schiff base ligands: Synthesis, characterization, crystal structure and catalytic activity in transfer hydrogenation of ketones

A new series of pincer type ruthenium(II) Schiff base complexes namely [Ru(CO)(PPh3)2(L1‒6)] (1–6) (where, L1‒6 ​= ​NOO ‒ donors of tri-dentate ligands) have been synthesized from ruthenium precursor such as [RuHCl(CO)(PPh3)3] containing tri-dentate Schiff bases ligands (H2L1‒H2L6). These ruthenium complexes were analyzed by elemental analysis and diverse characterizations such as FT‒IR, UV–Vis and NMR (1H and 31P) spectroscopy studies. The crystal structure of one of the complexes 5 ([Ru(CO)(PPh3)2L5]) was determined by single crystal X‒ray crystallography that revealed pincer type of coordination mode of complexes. Furthermore, complexes 1–6 have been utilized for transfer hydrogenation of aromatic ketones to secondary alcohols in the presence of i‒PrOH/KOH. The catalytic efficiency of complexes showed an efficient for transfer hydrogenation of ketones with alcohol as moderate to high conversions.

Syntheses of two copper(II) coordination polymers from a morpholine-based tridentate Schiff base ligand: crystal structures and magnetic properties

Two new one-dimensional (1-D) end-to-end azido and thiocyanato bridged Cu(II) coordination polymers, [Cu(L)(µ-1,3-N3)] n (ClO4) n (1) and [Cu(L)(µ-1,3-NCS)] n (ClO4) n (2) with a morpholine-based tridentate N,N,N-donor Schiff base ligand (1-methyl-1H-imidazol-2-yl)-N-[2-(morpholin-4-yl)ethyl]methanimine, L) have been synthesized. Compounds 1 and 2 have been characterized by elemental analyses and spectroscopic techniques. The X-ray single crystal structures of 1 and 2 show the formation of regular zigzag chains with µ-1,3-azido and µ-1,3-thiocyanate bridges, respectively. Variable temperature (2–300 K) magnetic studies indicate that 1 shows a ferromagnetic intrachain exchange interaction with g = 2.135(2) and J = 2.13(2) cm−1, while in 2 this interaction is antiferromagnetic with g = 2.1412(3) and J = –0.277(2) cm−1. X-band EPR spectra of 1 and 2 in frozen (143 K) DMF solution corroborate our magnetic studies.

Synthesis of oxidovanadium complexes containing coumarin and naphthalene: bromoperoxidase activity and DNA/BSA binding

Two tridentate Schiff base ligands, L1 and L2 , have been introduced in the synthesis of mononuclear oxidovanadium complexes with a co-ligand 1,10-phenanthroline. Two mononuclear complexes, [VO(L1)(1,10-phen)] (1) and [VO(L2)(1,10-phen)] (2), have been synthesized in high yields by reactions with [VO(acac)2] in 1:1 ratio in methanol under reflux with 1,10-phenanthroline as co-ligand. X-ray crystallographic studies unveil the structures of 1 and 2 showing L1 and L2 bind in O^N^O coordination. The complexes were characterized by using UV-Vis, IR, NMR and Mass spectral techniques. The physiochemical properties have been interpreted by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. The mimicking of vanadium haloperoxidase was investigated by bromination of phenol red in the presence of bromide and H2O2 with a rate of 2.68 × 102 (mol/L)−2 s−1. The DNA and BSA protein binding interactions of 1 and 2 have been explored by UV–Vis and fluorescence spectral methods; viscosity measurements reveal that the complexes interact with CT-DNA through intercalation in the order [VO(L1)(1,10-phen)](2.71 × 104) > [VO(L2)(1,10-phen)](9.67 ×103). The complexes exhibit binding interactions with BSA protein.

Crystal structure of [2-({[2-(dimethylamino-κN)ethyl]imino-κN}methyl)phenolato-κO](1,10-phen-anthroline-κ2 N,N')copper(II) perchlorate.

The title compound, [Cu(C11H15N2O)(C12H8N2)]ClO4 or [Cu(L)(phen)](ClO4) {where L refers to the deprotonated form of 2-[(2-di-methyl-amino-ethyl-imino)-meth-yl]phenol} and phen is 1,10-phenanthroline) is a mononuclear mixed ligand copper(II) complex. The CuII atom is coordinated by two N and one O atoms of the tridentate Schiff base ligand (HL) and two N atoms of the 1,10-phenanthroline ligand, resulting in a five-coordinate complex. The asymmetric unit of the title complex contains two crystallographically independent complex cations (a and b) with a slightly different geometry around the CuII ion. The value of the trigonality index τ, indicates that in both cations a and b, the CuII atoms display a square-pyramidal distorted trigonal-bipyramidal (SPDTBP) geometry, although the distortion is greater for cation a.

Dinuclear Zn(II) complexes with Schiff base ligands derived from 4-aminoantipyrine; crystal structure and catalytic activity in the synthesis of tetrazoles

Two new phenolato bridged dinucelar Zn(II) complexes, [Zn2(L1)2(N3)2] (1) and [Zn2(L2)2(N3)2] (2), were synthesized where HL1 and HL2 are tridentate Schiff base ligands obtained from the reaction of 4-aminoantipyrine with 5-bromo-2-hydroxybenzaldehyde and 2-hydroxybenzaldehyde, respectively. The ligands and complexes were characterized by elemental analysis and spectroscopic methods. Crystal structures of complexes 1 and 2 were determined by X-ray analysis which revealed the Zn(II) ions in both of these neutral dinuclear complexes are five coordinated and have distorted square pyramidal geometry. The equatorial plane of this geometry is filled by ONO-donor atoms of the ligands and the axial position is filled by azide co-ligand. Intermolecular interactions in the crystal structure of 1 and 2 were studied by Hirshfeld surface analysis. Due to the presence of azide ligand in the structure of these complexes, they were used as catalysts in the synthesis of 5-phenyl-1H-tetrazole from the reaction of benzonitrile and sodium azide. The results indicated that complexes 1 and 2 are active catalysts for the synthesis of tetrazoles from nitrile and azide cycloaddition reaction.

Instigating the in vitro antidiabetic activity of new tridentate Schiff base ligand appended M(II) complexes: From synthesis, structural characterization, quantum computational calculations to molecular docking, and molecular dynamics simulation studies

In search of novel medications that could be effective in preventing and treating diabetes, four new [Co(L)(H2O)3] (2), [Ni(L)(H2O)3] (3), [Cu(L)(H2O)] (4) and [Zn(L)(H2O)] (5) complexes were synthesized from 4‐Chloro‐2‐(((3‐mercapto‐5‐[pyridin‐4‐yl]‐4H‐1,2,4‐triazol‐4‐yl)imino)methyl)phenol ligand (H2L), which is obtained by the condensation of 5‐chlorosalicylaldehyde with 4‐amino‐5‐(pyridin‐4‐yl)‐4H‐1,2,4‐triazole‐3‐thiol in 1:1 ratio. The Fourier‐transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) (1H and 13C), elemental analyses, UV–visible, electron spin resonance (ESR), thermogravimetric analysis (TGA), scanning electron microscopy, energy dispersive X‐ray analysis (EDAX), and X‐ray diffraction (XRD) studies were used to successfully characterize the compounds. The ligand act in a tridentate manner and coordinates to the metal ions through Nazomethine, Ophenolic and Sthiol functionalities. On the premise of their spectral and physico‐analytical data; octahedral geometry for complex 2 and 3, while square planar and tetrahedral geometry for complex 4 and 5 was proposed. Theoretical calculations of the synthesized compounds have been performed by using density functional theory (DFT)/B3LYP method and parameters such as HOMO‐LUMO energy values and MESP were calculated. In vitro examinations against α‐amylase and α‐glucosidase reveal promising results for the compounds. Nickel (II) complex (3) against α‐amylase and zinc (II) complex (5) against α‐glucosidase were found to be good inhibitors. Molecular docking experiments against the receptors 1BSI and 5ZCC were done to support the observation and considerable binding energies and interactions were observed. Additionally, a 100‐ns molecular dynamics simulation (MDS) was done to assess the stability of the complex structures generated during in silico research, and it showed a stable conformation and binding pattern for the compounds.

Effect of di- and tri-ethylammonium cations on the structure and physicochemical properties of dioxido vanadium(V) Schiff base complexes

Four dioxido vanadium(V) complexes with formula [VO2(L)]− (where L = Schiff base ligand, formed by reacting 3‑hydroxy-2-naphtoic hydrazide with 5-chlorosalicylaldehyde or 5-bromosalicylaldehyde) have been isolated and structurally characterized based on elemental analysis, IR and UV–Vis spectra results. The X-ray crystal structure diffraction analyses of all complexes indicate a distorted square pyramidal geometry for the vanadium(V) atom, being coordinated by the tridentate Schiff base and two oxido groups. The complexes are charge-balanced by triethylammonium or diethylammonium cations, and the hydrogen bond interactions between the ionic species are discussed. Ionic vanadium complexes are characterized by better solubility in water compared to neutral molecules, and this represents an important feature if these compounds have to be used as pharmaceuticals. The stability of the complexes at pH = 2 and 7 was established by UV–Vis spectroscopy and compared to the previously studied potential insulin-mimetic vanadium(III-V) complexes with Schiff base ligands. The effect of the cation on the solubility of the complexes in water and their stability in solution has been described in detail.

Biological activity of mixed chelate copper(II) complexes, with substituted diimine and tridentate Schiff bases (NNO) and their hydrogenated derivatives as secondary ligands: Casiopeína's fourth generation

We synthesize and characterize nine copper(II) compounds. Four with general formula [Cu(NNO)(NO3)] and five mixed chelates [Cu(NNO)(N-N)]+, where NNO corresponds to asymmetric salen ligands (E)-2-((2-(methylamino)ethylimino)methyl)phenolate (L1) and (E)-3-((2-(methylamino)ethylimino)methyl)naphthalenolate (LN1); and their hydrogenated derivatives 2-((2-(methylamino)ethylamino)methyl)phenolate (LH1) and 3-((2-(methylamino)ethylamino)methyl)naphthalenolate (LNH1); and N-N correspond to 4,4′-dimethyl-2,2′-bipiridyne(dmbpy) or 1,10-phenanthroline (phen). Using EPR, the geometries of the compounds in solution in DMSO were assigned, [Cu(LN1)(NO3)] and [Cu(LNH1)(NO3)] a square-planar, [Cu(L1)(NO3)], [Cu(LH1)(NO3)], [Cu(L1)(dmby)]+ and [Cu(LH1)(dmby)]+ a square-based pyramid; and [Cu(LN1)(dmby)]+, [Cu(LNH1)(dmby)]+ and [Cu(L1)(phen)]+ and elongated octahedral. By X-ray it was observed that [Cu(L1)(dmby)]+ and. [Cu(LN1)(dmby)]+ presented a square-based pyramidal, and [Cu(LN1)(NO3)]+ a square-planar geometry. The electrochemical study showed that copper reduction process is a quasi-reversible system, where the complexes with hydrogenated ligands were less oxidizing. The cytotoxicity of the complexes was tested by MTT assay, all the compounds showed biological activity in HeLa cell line, the mixed compounds were the more active ones. Naphthalene moiety, imine hydrogenation and aromatic diimine coordination, increased biological activity. A structure-activity relationships were found: Log(IC50) = − 1.01(Epc) − 0.35(Conjugated Rings) + 0.87, for Schiff base complexes and Log(IC50) = 0.078(Epc) − 0.32(Conjugated Rings) + 1.94, for hydrogenated complexes; the less oxidizing species with a great number of conjugated rings presented the best biological activity. Complexes-DNA binding constants were obtained by uv-vis studies using CT-DNA, the results suggested that the complexes can interact through the grooves, except the phenanthroline mixed complex that intercalate with DNA. Gel electrophoresis study with pBR 322 showed that compounds can produce changes in the form of DNA and some complexes can cleave DNA in the presence of H2O2.

Cover Feature: Improvement of Solid Photoluminescence of Tridentate Schiff Base Pt(II) Foldamer by Hybridizing Poly (4‐Vinylpyridine) (Eur. J. Inorg. Chem. 36/2022)

The Cover Feature shows the bis(tridentate Schiff base Pt(II)) complex containing dimethyl sulfoxide (Pt2L2DMSO) as a combination of yellow disks, gray disks, orange cones, and a black curved line. Pt2L2DMSO is unfolding due to the steric repulsion of the bulky ligand. The blue hexagons connected to the branched black lines stand for poly(4-vinylpyridine) (P4VP). The green curved figure in the background indicates hybridization. The top image shows the hybridization of Pt2L2DMSO and P4VP, which causes a ligand exchange reaction for Pt2L2DMSO, forming a folding network structure in the yellow membrane. The yellow membrane exhibits red photoluminescence under ultraviolet irradiation (green wavy arrow). The reddish thunder expresses phosphorescence. The bottom image in the cover shows hybridization of Pt2L2DMSO and 4-vinylpyridine (4VP), which causes a ligand exchange reaction for Pt2L2DMSO, forming the folding columnar packing structure in the brown block crystal. The black wavy arrow indicates non-radiative deactivation. The metallofoldamer crystal does not exhibit solid photoluminescence under ultraviolet irradiation, while the metallofoldamer membrane is luminescent, thanks to the hybridization with P4VP. The background color changes gradually from orange to gray at the bottom to orange at the top, showing the improvement of photoluminescence from bottom to top. More information can be found in the Research Article by H. Achira and co-workers.

Improvement of Solid Photoluminescence of Tridentate Schiff Base Pt(II) Foldamer by Hybridizing Poly (4‐Vinylpyridine)

AbstractA series of bis(tridentate Schiff base platinum) complex (Pt2L2) linked with 2‐methylenepropane‐1,3‐diyl were synthesized, and their photophysical properties were examined to analyze different solid states. X‐ray crystallographic analysis indicated that Pt2L2 containing 4‐vinylpyridine (Pt2L24VP) as a ligand had a helically‐folded structure. It caused upfield chemical shifts and a redshift in UV‐Vis absorption spectra compared to the analogous mononuclear complex. Pt2L2 containing dimethylsulfoxide (Pt2L2DMSO) had no such helically‐folded structure due to the steric repulsion of DMSO. Pt2L24VP did not exhibit solid photoluminescence owing to the crystal packing. The mixture of poly(4‐vinylpyridine) (P4VP) and Pt2L2DMSO (Pt2L2DMSO−P4VP) showed a similar redshift in UV‐Vis absorption and excitation spectra to Pt2L24VP, implying the helically‐folded structure of Pt2L2 with P4VP coordination. The Pt2L2DMSO−P4VP exhibited solid photoluminescence with a longer phosphorescence lifetime (2.4 μs) than the Pt2L24VP crystals (0.5 μs), indicating regulated aggregation of the Pt2L2 frames in the P4VP matrix.

Cytotoxic profile study, DNA and protein binding activity of a new dinuclear nickel(II) thiocyanato complex

One new binuclear Ni(II) complex with the molecular formula [Ni2(L)2(SCN)2(μ-SCN)2] (1) has been synthesized using a tridentate Schiff base ligand (L), formed by the condensation between quinoline-2-carboxaldehyde and N,N-dimethylethylenediamine. Complex 1 was characterized by FT-IR, UV-vis, and ESI-mass spectroscopy techniques, as well as elemental analysis, cyclic voltammetry, and single-crystal X-ray crystallography. The X-ray diffraction analysis of 1 indicated a centrosymmetric complex with nickel(II) centers in a distorted octahedral geometry and double bridged by thiocyanate anions via end-to-end (μ-1,3) fashion. The interaction of 1 with CT-DNA was explored by UV-vis and fluorescence spectroscopy, viscosity and cyclic voltammetry which indicated a moderate intercalation of the complex with CT-DNA. The protein binding study of 1 with BSA and HSA was investigated by various spectroscopic methods and indicated a static quenching process. In addition, 1 showed prominent in vitro cytotoxic activity against human melanoma (A375) and human breast carcinoma (MDA-MB-231) cell lines under the identical condition with IC50 value of 149.06 and 124.22 µM, respectively.

Development of new tridentate ligands bearing hydrazone motif and their diorganotin(IV) complexes: Synthesis, spectral, antimicrobial and molecular docking studies

Current antimicrobial drug discovery and advancement attempts are aimed to identify new complexes that can work effectively against the infections caused by microbes. The aim of present study was to synthesize new diorganotin(IV) complexes of N'-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)-2-nitrobenzohydrazide (H2L1), N'-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)-3-methoxybenzohydrazide (H2L2) and N'-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)-4-methylbenzohydrazide (H2L3) Schiff base ligands with formula R2SnL1−3 (where R = Me, Et, Bu and Ph). Various spectral and physico-analytical techniques such as elemental analysis, FT-IR, multinuclear (1H, 13C, 119Sn) NMR, HRMS and XRD were utilized to structurally elucidate the prepared compounds. Based on the spectral data, it was concluded that ligands behave in a tridentate manner and coordinates to the central tin atom through ONO donor atoms. Furthermore, the synthesized compounds were examined for in vitro antimicrobial activity against four bacterial and two fungal strains. Among the examined compounds, Ph2SnL1 complex (MIC = 0.0095 µmol/mL) was found to be the most active. To rationalize the preferred mode of interactions of the most active compound, a molecular docking study of compound Ph2SnL1 was executed in the binding site of 3-oxoacyl-[acyl-carrier-protein] synthase 2 (FabF) of E. coli and sterol 14-alpha demethylase of C. albicans. Compound Ph2SnL1 inhibits the microbes effectively and it could be an effective and new candidate for the modulation of various infections. New diorganotin(IV) complexes (4–15) were prepared from tridentate Schiff base hydrazones (1–3). The compounds were examined for in vitro antimicrobial activity. Further, molecular docking study of the most potent compound Ph2SnL1 (7) was performed against the enzyme 3-oxoacyl-[acyl-carrier-protein] synthase 2 (FabF) of E. coli and sterol 14-alpha demethylase of C. albicans.