Complexes In DMSO Research Articles

Regulation of Buried Interface through the Rapid Removal of PbI2·DMSO Complex for Enhancing Light Stability of Perovskite Solar Cells

Regulation of Buried Interface through the Rapid Removal of PbI₂·DMSO Complex for Enhancing Light Stability of Perovskite Solar Cells

Enoxacin fluoroquinolone antibacterial agent complexes with Pt(IV), Ru(III) and Ir(III) ions: Synthesis, spectroscopic, physicochemical characterizations and biological studies

The synthesis, physicochemical characterizations, and biological investigations on the chelation of the antibiotic medication enoxacin (EXN) with certain vital metal ions, such as platinum(IV), ruthenium(III), and iridium(III) are discussed in this study. These compounds structures were interpreted based on elemental analysis and spectral measurements (FTIR, 1H-NMR, UV-Vis electronic, and XRD). The findings show that there is same coordination pathway for the chelation behavior of enoxacin complexes: a monodentate manner. The Pt(IV), Ru(III), and Ir(III) complexes are coordinated through the N atom of the piperazine ring, which is an unusual mode of coordination for this class of compounds. The dissolved complexes in DMSO were found to have non-electrolyte nature based on their molar conductance measurements. The formula for these complexes is [Pt(EXN)3(H2O)2Cl] (1), [Ru(EXN)3(H2O)3] (2), and [Ir(EXN)3(H2O)3] (3). Using scanning electron microscope (SEM) analysis and X-ray powder diffraction (XRD), the nano-scale range of the Pt(IV), Ru(III), and Ir(III) complexes has been determined. Results of in vitro cytotoxicity were examined using MCF-7 cells (human breast cancer cell line) and HepG-2 cells (human hepatocellular carcinoma) that had been grown. The cytotoxic activity of the metal complexes demonstrated a cytotoxic effect against the growth of human breast and liver cancer cell lines.
 KEY WORDS: Enoxacin, Platinum(IV), Complexity, Spectral analyses, Biological assessments
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 685-699. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.11

Understanding the behavior of a potential anticancer lamotrigine in explicit solvent (water and DMSO) using quantum mechanical tools and abinitio molecular dynamics

Lamotrigine is a medication used to treat epilepsy and help stabilize mood in individuals with bipolar disorder. Epilepsy includes different types of seizures, such as focal seizures, tonic-clonic seizures, and Lennox-Gastaut syndrome, and Lamotrigine is specifically designed to manage this condition. The effectiveness of the drug relies on how it interacts with different liquid environments. In our study, we employed two methods, namely PBE0-D3/def2-TZVP, for optimizations and various calculations. We utilized this approach for NBO, NCI, and wavefunction assay. Additionally, we used PBE0-D3/def2-TZVP and DLPNO-CCSD(T) for analyzing LED, MD, and the bond energy of Lamotrigine in both a vacuum and a complex setting (with water and DMSO). Our findings revealed that Lamotrigine can break down into four fragments: triazine, dichlorophenyl-, 10 amine at the second position in triazine, and 10 amines at the fourth position in triazine. The bond energy for these fragments is measured at 351.84 kcal/mol. NBO provided insights into the electronic transition energies of Lamotrigine in different environments, including a vacuum and with solvents. NCI helped us understand the non-covalent interactions of Lamotrigine in both a vacuum and with water and DMSO (complex) molecules through their two pores: inter and intra interactions. We further explored binding energies and total binding energies of Lamotrigine with water and DMSO. Simulations indicated that Lamotrigine with DMSO pore1 exhibited the highest energy changes over time with a positive sign, while Lamotrigine with water pore2 showed the lowest energy changes over time with a negative sign. In our implicit solvation assay using the SMD model and the CPCM method, we found that Lamotrigine with water had a lower free energy compared to the Lamotrigine-DMSO system.

Dibromo- and Dichlorotriphenylphosphino N-Acyclic Carbene Complexes of Platinum(II)—Synthesis and Cytotoxicity

Some new dichloro- and dibromotriphenylphosphino isonitrile and N-acyclic (NAC) carbene complexes of platinum(II) were synthesized, starting from suitable dinuclear precursors. The reaction of cyclohexylisonitrile with trans-[Pt(μ-X)X(PPh3)]2, followed by the addition of N,N-diethylamine afforded the corresponding N-acyclic carbene (NAC)derivatives cis-[PtX2(PPh3)(NAC)] in 61–64% isolated yield. The cis geometry was attributed based on the comparison with known structures. The stability of the complexes in pure DMSO, DMSO/H2O, and DMSO/NaClaq mixtures was evaluated. While pure DMSO, as well as DMSO/H2O, did not affect the nature of either dichloro- or dibromo-compounds, dibromo derivatives were not stable in the presence of chloride ions. Since a high concentration of chloride ions is essential to perform in vitro cell assays, only dichlorocomplexes were tested as cytotoxic agents against HepG2 and human tumor cells. Among the tested complexes, NAC derivatives showed a moderate effect on MSTO-211H.

Striking stability of a mixed-valence thallium(III)-thallium(I) complex in some solvents

At the dissolution of solid anhydrous thallium(III) trifluoromethanesulfonate, Tl(CF3SO3)3, or thallium(III) trifluoroacetate, Tl(CF3COO)3, in dimethylsulfoxide (dmso) or N,N,N’,N’-tetramethylurea (tmu), intensely red-colored complexes are formed. This red thallium complex is stable for years in dmso, while it is reduced fairly rapidly to thallium(I) in tmu with a half-life time of an hour. At the dissolution of Tl(CF3SO3)3 in N,N-dimethylpropyleneurea (dmpu) an immediate reduction to thallium(I) takes place. A stable colorless aqueous thallium(III) solution is obtained at the dissolution in acidic water. Stable dmso solutions and solid dmso solvates of thallium(III) perchlorate, nitrate and trifluormethanesulfonate can be prepared by adding dmso to concentrated acidic aqueous thallium(III) solutions. These experimental observations conclude that the pure solids Tl(CF3SO3)3 and Tl(CF3COO)3 play an essential role in the formation of the red-colored thallium complexes. 205Tl NMR data show that the red thallium complex contains equal amounts of thallium(III) and thallium(I). The structure of the red thallium complex in dmso, as determined by EXAFS, has Tl–O bond distances of 2.216(3) and 2.80(2) Å, which are in very close agreement with the bond distances obtained in the pure dmso solvates of the thallium(III) and thallium(I) ions, respectively, and a Tl···Tl distance of 3.49(1) Å bridged by oxygen atoms. From the EXAFS data it is impossible to distinguish if dmso molecules and/or trifluoromethanesulfonate ions act as bridges. DFT calculations could eliminate some structures due to the irrelevant structural parameters or the energetics of the proposed reactions.

The role of redox active copper(II) on antioxidant properties of the flavonoid baicalein: DNA protection under Cu(II)-Fenton reaction and Cu(II)-ascorbate system conditions

The antioxidant properties of flavonoids are mediated by their functional hydroxyl groups, which are capable of both chelating redox active metals such as iron, copper and scavenging free radicals. In this paper, the antioxidant vs. prooxidant and DNA protecting properties of baicalein and Cu(II)-baicalein complexes were studied under the conditions of the Copper-Fenton reaction and of the Copper-Ascorbate system. From the relevant EPR spectra, the interaction of baicalein with Cu(II) ions was confirmed, while UV–vis spectroscopy demonstrated a greater stability over time of Cu(II)-baicalein complexes in DMSO than in methanol and PBS and Phosphate buffers. An ABTS study confirmed a moderate ROS scavenging efficiency, at around 37%, for both free baicalein and Cu(II)-baicalein complexes (in the ratios 1:1 and 1:2). The results from absorption titrations are in agreement with those from viscometric studies and confirmed that the binding mode between DNA and both free baicalein and Cu-baicalein complexes, involves hydrogen bonds and van der Waals interactions. The DNA protective effect of baicalein has been investigated by means of gel electrophoresis under the conditions of the Cu-catalyzed Fenton reaction and of the Cu-Ascorbate system. In both cases, it was found that, at sufficiently high concentrations, baicalein offers some protection to cells from DNA damage caused by ROS (singlet oxygen, hydroxyl radicals and superoxide radical anions). Accordingly, baicalein may be useful as a therapeutic agent in diseases with a disturbed metabolism of redox metals such as copper, for example Alzheimer's disease, Wilson's disease and various cancers. While therapeutically sufficient concentrations of baicalein may protect neuronal cells from Cu-Fenton-induced DNA damage in regard to neurological conditions, conversely, in the case of cancers, low concentrations of baicalein do not inhibit the pro-oxidant effect of copper ions and ascorbate, which can, in turn, deliver an effective damage to DNA in tumour cells.

Selective Detection of Copper Ions and Biological Activities of Isoniazid Schiff Bases

AbstractFollowing mechanical milling, the condensation reaction of the corresponding heterocyclic aldehydes with Isoniazid yields the Schiff base (E)‐N′‐((1H‐pyrrol‐2‐yl) methylene)isonicotinohydrazide (S1) and (E)‐N′‐(Thiophen‐2‐ylmethylene)isonicotinohydrazide (S2) supported heterocyclic derivatives. The structures of the Schiff bases, S1 and S2 were confirmed by 1H NMR, 13C NMR and IR spectroscopy. Copper ions (Cu2+) were trapped by S1 in DMSO to form the yellow‐coloured complex Cu‐(E)‐N′‐((1H‐pyrrol‐2‐yl)methylene) isonicotinohydrazide (Cu2++S1) with high sensitivity and selectivity. But the same ligand S1 could not be able to capture other metal ions tested for this work (namely, Co2+, Ni2+, Zn2+, Mn2+, Hg2+, Cd2+, Pb2+, Fe2+, and Fe3+) in DMSO. UV‐visible spectroscopic results confirmed the complex formation (Cu2++S1) with copper ions, but not with the other ions. Analysis of non‐covalent interactions (NCI) of ligand S1 with Ni2+, Cu2+ and Zn2+ in DMSO were investigated by density functional theory (DFT). NCI analysis of S1 by Cu2+ ions in DMSO was in good agreement with the experimental results. S2 did not react with any metal ions used in this study to form a complex in DMSO and the same was confirmed by UV‐Visible spectra. Reasonably good antibacterial activity was observed with S1, S2, Cu2++S1 compared to amoxicillin against Gram‐negative bacteria (K. pneumoniae, E. coli), Gram‐positive bacteria (S. aureus, S. pneumoniae), and fungal strain (C. albicans).

New Cu(II), Mn(II) and Mn(III) Schiff base complexes cause noncovalent interactions: X-ray crystallography survey, Hirshfeld surface analysis and molecular simulation investigation against SARS-CoV-2

In this study, polynuclear Cu(II) complex (1), Mn(II) and Mn(III) complex (2) have been prepared with a Schiff base ligand derived from 2-Hydroxy-3-methoxybenzaldehyde with 2-amino-2-methyl-1-propanol. The compounds were characterized by elemental analysis, FT-IR, and UV–Vis spectroscopy. The molecular and crystal structures of (1–2) were determined by the single-crystal x-ray diffraction technique. It turned out that Cu(II) complex (1) forms an S4-symmetrical tetrameric cage structure, with square-planar coordinated Cu and bridging O atoms at the vertexes of the approximate cube. In the crystal structure of 1, there are large channels along the c-axis, between the tetramers; the solvent– DMSO molecules, occupies these channels. In turn, the complex (2) creates a centrosymmetric trimeric structure, with three octahedrally coordinated Mn ions bridged by O atoms from ligand molecules and acetate ions. The electrochemical behavior studies of the complexes in DMSO displayed the electronic effects of the groups on the redox potential. The redox behavior of Schiff base (1) and (2) complexes included quasi -reversible and irreversible voltammograms, respectively. Intermolecular interactions in the solid states were studied by Hirshfeld surface analysis. These studies provide a comprehensive description of these inter-contact exchanges using an attractive graphical representation using Hirshfeld surfaces and fingerprint plots, along with enrichment ratios. Furthermore, assessment of the inhibitory effect against coronavirus (main protease SARS-CoV-2) was performed by a molecular docking study for both complexes (1 and 2). Both complexes showed a good affinity for CoV-2 for PDB protein ID: 6M03 and 6Y2F.

Complex Additive‐Assisted Crystal Growth and Phase Stabilization of α‐FAPbI3 Film for Highly Efficient, Air‐Stable Perovskite Photovoltaics

AbstractSolution‐processed formamidinium lead iodide (FAPbI3) perovskite is entropically metastable, and it exhibits condition‐induced crystal polymorphism. Under an ambient atmosphere, the photoactive black α‐FAPbI3 converts easily to photoinactive yellow δ‐FAPbI3. This α → δ phase degradation is further accelerated upon exposure to high temperature/humidity, directly threatening the performance and stability of perovskite solar cells (PSCs). Herein, cesium iodide‐lead iodide:dimethyl sulfoxide (CsI‐PbI2:DMSO) complex is introduced as a phase stabilizer to modulate the crystallization of α‐FAPbI3 perovskite from δ‐FAPbI3 precursor and simultaneously, serve as a defect passivator to suppress trap states formation. Theoretical simulations and experimental results reveal the pivotal role of complex additive in optimizing the energy band alignment and optoelectronic properties of α‐FAPbI3 perovskite and most importantly, hindering the α → δ phase transition. The best PSC device based on the additive‐engineered perovskite film achieves an efficiency of ≈21.9%, which is ≈11% higher than that of its pristine counterpart (≈19.8%). In addition, the incorporation of CsI‐PbI2:DMSO complex remarkably enhances the long‐term stability and photostability of the PSCs by inhibiting ion migrations and preserving the α‐phase in FAPbI3 perovskite. The additive engineering presented herein offers a route to produce FAPbI3‐based PSCs with improved performance, stability, and reproducibility.

Stabilization of {Ag20(StBu)10} and {Ag19(StBu)10} Toroidal Complexes in DMSO: HPLC-ICP-AES, PL, and Structural Studies

The presence of DMSO provides a unique ability to stabilize silver toroidal complexes in the direct reaction between AgStBu and AgNO3 at 80 °C. Slow cooling results in large crystals of [NO3@Ag19.2(StBu)10(DMSO)5.2(NO3)8.2]·3DMSO (1), which were isolated and characterized by single crystal X-ray diffraction (SCXRD) analysis. The crystal structure contains both {Ag20(StBu)10} and {Ag19(StBu)10} clusters. The solution of these material in DMSO was studied with HPLC techniques, which demonstrated the presence of both complexes in solution. The use of [SiW12O40]4– as counter anion gives crystals of a double complex salt [Ag17.8(NO3)3.8(StBu)10][SiW12O40]·30DMSO (2) under the same conditions. Temperature-dependent photoluminescence (PL) was studied.

Low-Dimensional Compounds Containing Bioactive Ligands. Part XIX: Crystal Structures and Biological Properties of Copper Complexes with Halogen and Nitro Derivatives of 8-Hydroxyquinoline

Six new copper(II) complexes were prepared: [Cu(ClBrQ)2] (1a, 1b), [Cu(ClBrQ)2]·1/2 diox (2) (diox = 1,4-dioxane), [Cu(BrQ)2] (3), [Cu(dNQ)2] (4), [Cu(dNQ)2(DMF)2] (5) and [Cu(ClNQ)2] (6), where HClBrQ is 5-chloro-7-bromo-8-hydroxyquinoline, HBrQ is 7-bromo-8-hydroxyquinoline, HClNQ is 5-chloro-7-nitro-8-hydroxyquinoline and HdNQ is 5,7-dinitro-8-hydroxyquinoline. Prepared compounds were characterised by infrared spectroscopy, elemental analysis and by X-ray structural analysis. Structural analysis revealed that all complexes are molecular. Square planar coordination of copper atoms in [Cu(XQ)2] (XQ = ClBrQ (1a, 1b), BrQ (3) and ClNQ (6)) and tetragonal bipyramidal coordination in [Cu(dNQ)2(DMF)2] (5) complexes were observed. In these four complexes, bidentate chelate coordination of XQ ligands via oxygen and nitrogen atoms was found. Hydrogen bonds stabilizing the structure were observed in [Cu(dNQ)2(DMF)2] (5) and [Cu(ClNQ)2] (6), no other nonbonding interactions were noticed in all five structures. The stability of the complexes in DMSO and DMSO/water was evaluated by UV-Vis spectroscopy. Cytotoxic activity of the complexes and ligands was tested against MCF-7, MDA-MB-231, HCT116, CaCo2, HeLa, A549 and Jurkat cancer cell lines. The selectivity of the complexes was verified on a noncancerous Cos-7 cell line. Antiproliferative activity of the prepared complexes was very low in comparison with cisplatin, except complex 3; however, its activity was not selective and was similar to the activity of its ligand HBrQ. Antibacterial potential was observed only with ligand HClNQ. Radical scavenging experiments revealed relatively high antioxidant activity of complex 3 against ABTS radical.

Triplet Emitting C^N^C Cyclometalated Dibenzo[c,h]Acridine Pt(II) Complexes.

In a series of Pt(II) complexes [Pt(dba)(L)] containing the very rigid, dianionic, bis-cyclometalating, tridentate C^N^C2- heterocyclic ligand dba2- (H2dba = dibenzo[c,h]acridine), the coligand (ancillary ligand) L = dmso, PPh3, CNtBu and Me2Imd (N,N'-dimethylimidazolydene) was varied in order to improve its luminescence properties. Beginning with the previously reported dmso complex, we synthesized the PPh3, CNtBu and Me2Imd derivatives and characterized them by elemental analysis, 1H (and 31P) NMR spectroscopy and MS. Cyclic voltammetry showed partially reversible reduction waves ranging between -1.89 and -2.10 V and increasing along the series Me2Imd < dmso ≈ PPh3 < CNtBu. With irreversible oxidation waves ranging between 0.55 (L = Me2Imd) and 1.00 V (dmso), the electrochemical gaps range between 2.65 and 2.91 eV while increasing along the series Me2Imd < CNtBu < PPh3 < dmso. All four complexes show in part vibrationally structured long-wavelength absorption bands peaking at around 530 nm. TD-DFT calculated spectra agree quite well with the experimental spectra, with only a slight redshift. The photoluminescence spectra of all four compounds are very similar. In fluid solution at 298 K, they show broad, only partially structured bands, with maxima at around 590 nm, while in frozen glassy matrices at 77 K, slightly blue-shifted (~580 nm) bands with clear vibronic progressions were found. The photoluminescence quantum yields ΦL ranged between 0.04 and 0.24, at 298 K, and between 0.80 and 0.90 at 77 K. The lifetimes τ at 298 K ranged between 60 and 14040 ns in Ar-purged solutions and increased from 17 to 43 µs at 77 K. The TD-DFT calculated emission spectra are in excellent agreement with the experimental findings. In terms of high ΦL and long τ, the dmso and PPh3 complexes outperform the CNtBu and Me2Imd derivatives. This is remarkable in view of the higher ligand strength of Me2Imd, compared with all other coligands, as concluded from the electrochemical data.

Impact of denticity of chromone/chromene thiosemicarbazones in the ruthenium(II)‐DMSO complexes on their cytotoxicity against breast cancer cells

AbstractDenticity plays a prominent role in the cytotoxicity of metal complexes. The impact of ligand denticity of chromone/chromene thiosemicarbazones (TSCs) in the Ru(II)‐DMSO complexes on the cytotoxicity of cancer cells was evaluated. Ru(II)‐DMSO complex containing tridentate chromone TSC (D1) exhibited better in vitro anticancer activity than the one with bidentate chromene TSC (D2). Using the optimized structures of the complexes, the reason behind the same was attributed to the thermodynamically stable nature of the tridentate system. Hydrolysis study of the complexes showed the kinetically labile nature of the chloride ligand in the tridentate species with respect to the bidentate counterpart. The selective cytotoxicity of complex D1 against breast cancer cells and its less toxicity against normal cells demonstrated the effective anticancer potential of the complex. Further, the binding efficacy of the complexes against DNA and BSA, along with imaging and flow cytometry experiments, warranted the effective cell death induced by the complexes against breast cancer cells via apoptosis.

Synthesis and characterization of copper complexes of phenylpiperazine ring-based ligands and evaluation of their antimicrobial, BSA binding, computational, and molecular docking studies

This paper describes the synthesise of copper complexes of phenylpiperazine ring-based ligands and characterization via physical and spectroscopic methods. Structure of complexes has been proposed on the basis of UV-vis, IR and Mass fragmentation pattern and additionally supported by electrochemical and thermogravimetric analysis. Low molar conductance value of metal complexes in water and DMSO suggest non-ionic nature of complexes which is in agreement of proposed structure. TGA curve, where loss of coordinated solvent molecules starts early followed by loss of ligand itself also support the proposed structures. Percentage ash content analysis also indicate that only one copper metal is binding to the ligands reported here. Antibacterial activity of metal complexes has been performed by agar well diffusion method and indicated these metal complexes possess higher activity than the corresponding ligands. Binding interaction of these complexes were studied with BSA protein by UV-vis spectroscopic methods and binding constant was calculated which indicated that the complexes are having moderate affinity. Some complexes were also geometrically optimized to lowest energy ground state by using DFT calculations. Docking study of these optimized structures with BSA protein revealed these metal complexes exhibit hydrophobic interaction owing to the aromatic bulk in the ligand.

Synthesis, characterization, spectral studies and evaluation of noncovalent interactions in co-crystal of μ-oxobridged polymeric copper(II) complex derived from pyrazolone by theoretical studies

The new co-crystal of μ-oxobridged polymeric copper(II) complex {[0.714(9) CuII2(HL-CH2OH)2].[0.286(9) CuII2(HL-CHO2H)2]}n with Schiff base ligand derived from pyrazolone, (HL = 4-[(2-hydroxy-3-methoxybenzylidene)amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3-one), was synthesized and characterized by spectral and analytical techniques. The optimal and unexpected quality structures of the copper (II) polymer complex were determined using X-ray. Crystals are monoclinic, a = 7.8472(2), b = 12.5860(3), c = 17.0842(3) Å, β = 97.140(2)° and space group P21/c. The complexes are 4 + 1 coordinated, with four standard coordination distances in a square-planar geometry and a fifth, longer, secondary coordination distance at the square pyramid's apex. The basic complexes have a Ci-symmetrical Cu2L2 composition and extend into polymeric chains along the x crystallographic axis due to the longer contact. The electrochemical properties of complex in DMSO displayed the electronic effects on the groups on redox potential. The density functional theory by B3LYP method with (6-311 G) basis set was used to optimize the molecular geometry of the copper complex. Following the optimized DFT, FT-IR spectroscopy was used to determine geometric characteristics such as bond length and bond angle, which were then compared to experimental data. The intermolecular interactions were characterized using X-ray crystal structure analysis, HS (Hirshfeld surface analysis) and FPs (fingerprint diagrams). In addition, QTAIM (Quantum Theory of Atoms in Molecules) analysis was studied to determine the type of bonds and the energies of the metal-ligand bond. The adsorption process of complexes (1) and (2) in the aqueous phase on graphene oxide (GO) was calculated by the Monte Carlo adsorption locator. The results showed complex (2) had a high binding efficiency on GO compared with complex (1). The molecular docking study was also carried out for the copper complex to find its binding affinity to protein B-cell lymphorna (BCL-2, PDB ID: 4LXD).

Confirming the Molecular Basis of the Solvent Extraction of Cadmium(II) Using 2-Pyridyl Oximes through a Synthetic Inorganic Chemistry Approach and a Proposal for More Efficient Extractants.

The present work describes the reactions of CdI2 with 2-pyridyl aldoxime (2paoH), 3-pyridyl aldoxime (3paoH), 4-pyridyl aldoxime (4paoH), 2-6-diacetylpyridine dioxime (dapdoH2) and 2,6-pyridyl diamidoxime (LH4). The primary goal was to contribute to understanding the molecular basis of the very good liquid extraction ability of 2-pyridyl ketoximes with long aliphatic chains towards toxic Cd(II) and the inability of their 4-pyridyl isomers for this extraction. Our systematic investigation provided access to coordination complexes [CdI2(2paoH)2] (1), {[CdI2(3paoH)2]}n (2), {[CdI2(4paoH)2]}n (3) and [CdI2(dapdoH2)] (4). The reaction of CdI2 and LH4 in EtOH resulted in a Cd(II)-involving reaction of the bis(amidoxime) and isolation of [CdI2(L’H2)] (5), where L’H2 is the new ligand 2,6-bis(ethoxy)pyridine diimine. A mechanism of this transformation has been proposed. The structures of 1, 2, 3, 4·2EtOH and 5 were determined by single-crystal X-ray crystallography. The complexes have been characterized by FT-IR and FT-Raman spectra in the solid state and the data are discussed in terms of structural features. The stability of the complexes in DMSO was investigated by 1H NMR spectroscopy. Our studies confirm that the excellent extraction ability of 2-pyridyl ketoximes is due to the chelating nature of the extractants leading to thermodynamically stable Cd(II) complexes. The monodentate coordination of 4-pyridyl ketoximes (as confirmed in our model complexes with 4paoH and 3paoH) seems to be responsible for their poor performance as extractants.

Crystal structures, electrochemical properties and theoretical studies of three New Zn(II), Mn(III) and Co(III) Schiff base complexes derived from 2-hydroxy-1-allyliminomethyl-naphthalen

Three novel complexes of the Schiff base, 2-hydroxy-1-allyliminomethyl-naphthalen (HL), namely ZnII(HL)2 (1), polymeric [(MnIII(HL)2)(N3)2]n (2), and CoIII(HL)3 (3) were synthesized from the reaction of ZnBr2•2H2O, MnCl2•2H2O and Co(OAc)2•4H2O with the Schiff base ligand. The complexes were characterized by elemental analysis, FT-IR, UV-vis, as well as by the single-crystal X-ray diffraction technique. In all these complexes, central metal ions were coordinated by O and N atoms of the Schiff base ligand. It was found that the Zn complex (1) was C2-symmetrical, with the Zn ion in quite a regular tetrahedral environment. In turn, the Mn complex (2) made 1D-coordination polymer with N3 linkers between also symmetrical (Ci) Mn(HL)2 monomers, with six-coordinated Mn ion in an octahedral environment. Finally, the Co ion in Co(HL)3 complex (3) was also octahedrally 6-coordinated. Additional solvent (DMSO) molecules are built in the crystal architecture. The electrochemistry of complexes in DMSO displayed a metal-centered reduction peak corresponding to the ZnII/I- ZnI/0, MnIII/II- MnII/I, and CoIII/II - CoII/I at (-1.15,-1.53), (-0.11,-1.79) and (-0.76, -1.69) V, respectively. The molecular geometry of the complexes was optimized using the density functional theory with the basic set (B3LYP / 6-311G). After optimal DFT, the electron transfer spectrum was calculated theoretically and compared with the experimental results. Hirshfeld surfaces and fingerprint plots are used to visualize and analyze intermolecular interactions. The Hirshfeld surface analysis showed that the crystal cohesion of the structures of the three complexes is established via H•••H, C•••H/H•••C, and O•••H/H•••O the dominant contacts. As well as, molecular docking studies were carried out for all complexes to find their binding affinity with protein (PDB ID: 1LRI). Molecular binding studies have shown good interaction with the intended drug targets.

2,2′-Bipyridine based biologically active mixed ligand metal(II) complexes: Synthesis, characterization, DFT and antioxidant studies

Mixed ligand [CoL(bpy)], [NiL(bpy)], [CuL(bpy)] and [ZnL(bpy)] complexes were synthesized from Schiff base ligand L, metal(II) acetates of Co, Ni, Cu and Zn with 2,2′-bipyridine (bpy). The synthesized compounds were characterized using molar conductance, elemental analyses, 1H-NMR, FTIR and mass spectral studies. The geometry of metal complexes has been assigned by magnetic moment analysis and UV-vis spectral techniques. The X-band ESR spectra of [CuL(bpy)] complex in DMSO were recorded at room temperature and liquid nitrogen temperature. Grain size of metal complexes was predicted using Powder XRD. Computational DFT studies were performed using Gaussian 6.0 program package. HOMO-LUMO of L, optimized geometry, bond angle and bond length calculations were preceded at B3LYP/GENECP level with 6-31G (d,p) basis sets. Antimicrobial and antioxidant activities of complexes were evaluated.

Indium(III)/2-benzoylpyridine chemistry: interesting indium(III) bromide-assisted transformations of the ligand.

Reactions of 2-benzoylpyridine, (py)(ph)CO, with InX3 (X = Cl, Br) in EtOH at room temperature have been studied. The InCl3/(py)(ph)CO system has provided access to complex [InCl3{(py)(ph)CO}(EtOH)]·{(py)(ph)CO} (1) and the byproduct {(pyH)(ph)CO}Cl (2). The reaction of InBr3 with (py)(ph)CO has led to a mixture of (L)[InBr4{(py)(ph)CO}] (3) and [In2Br4{(py)(ph)CH(O)}2(EtOH)2] (4), where L+ is the 9-oxo-indolo[1,2-a]pyridinium cation and (py)(ph)CH(O)- is the anion of (pyridin-2-yl)methanol. Based on solubility and crystallisation time differences between the two components of the mixture, complex 4 was isolated in pure form, i.e. free from 3. The formations of the counterion L+ and the coordinated (py)(ph)CH(O)- anion represent clearly InBr3-promoted/assisted transformations. Reaction mechanisms have been proposed for the formation of 2, 3 and 4. Complex 4 could also be isolated by the reaction of InBr3 and pre-formed (py)(ph)CH(OH) in EtOH. The solid-state structures of 1, 3 and 4 were determined by single-crystal X-ray crystallography, while the identity of the salt 2 was confirmed by microanalyses and a variety of spectroscopic techniques, including ESI-MS spectra. In the indium(III) complexes, the metal ions are 6-coordinate with a distorted octahedral geometry. The halogeno groups (Cl-, Br-) in the three complexes are terminal. The (py)(ph)CO molecule behaves as a N,O-bidentate (1.11) ligand in 1 and 3. A terminal EtOH ligand completes the coordination sphere of InIII in 1. The alkoxo oxygen atoms of the two 2.21 (py)(ph)CH(O)- ligands doubly bridge the InIII centers in 4 creating a {InIII2(μ-OR)2}4+ core; a nitrogen atom of one reduced organic ligand, two bromo ions and one terminal EtOH molecule complete the 6-coordination at each metal centre. Complexes 1, 3 and 4 were characterised by IR and Raman spectroscopies, and the data were discussed in terms of their known solid-state structures. Molar conductivity data and 1H NMR spectra were used in an attempt to probe the behaviour of the complexes in DMSO. The to-date observed metal ion-assisted/promoted transformations of (py)(ph)CO are also discussed.

A new photoactivable NO-releasing {Ru-NO}6 ruthenium nitrosyl complex with a tetradentate ligand containing aniline and pyridine moieties.

A new type of photoactivable NO-releasing ruthenium nitrosyl complex, [Ru(EPBP)Cl(NO)], with a tetradentate ligand, N,N'-(ethane-1,2-diyldi-o-phenylene)-bis(pyridine-2-carboxamide) (= H2 EPBP) was synthesized. Single crystal X-ray crystallography revealed that the complex has a distorted octahedral coordination geometry and NO is positioned at cis to Cl- ion. NO-photolysis was observed under a white room light. The photodissociation of Ru-NO bond was identified by various techniques including X-ray crystallography, IR, UV/Vis absorption, electron paramagnetic resonance (EPR), and NMR spectroscopies. Quantum yields for the NO-photolysis of the complex in CH3 OH, CHCl3 , DMSO, CH3 CN, and CH3 NO2 were measured to be 0.19-0.36 with 400 (±5) nm excitation. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were performed to understand the details of the photodissociation of the complex. The calculations suggest that the NO photolysis is most likely initiated by the electronic transition from the aniline moiety π MOs (π (aniline)) of the EPBP2- chelating ligand to the π-antibonding MO of Ru-NO (π*(Ru-NO)). Experimental and theoretical investigations indicate that the EPBP2- ligand provides an effective platform forming ruthenium nitrosyl complexes useful for NO-photoreleasing.