Tridentate Chelating Research Articles

Synthesis, structural characterization, CT-DNA interaction study and antithrombotic activity of new ortho-vanillin-based chiral (Se,N,O) donor ligands and their Pd complexes

Two new selenated ligands: (S)-BnSeCH2CH(Bn)N = CH-C6H3-3-OCH3-2-OH ((S)-L1H) and (S)-BnSeCH2CH(Bn)NH-CH2-C6H3-3-OCH3-2-OH ((S)-L2H) incorporating ortho-vanillin moiety and their respective palladium(II) complexes (S)-1 and (S)-2 were synthesized in a high-yielding procedures. All compounds were characterized by various spectroscopic techniques such as 1H, 13C{1H} NMR, FT-IR, and UV–Visible. Further, the elemental and single crystal X-ray diffraction analyses of complexes showed that the deprotonated ligands ((S)-L1 and (S)-L2) coordinated to central palladium as tridentate (Se,N,O−) chelates of composition [PdCl(L1-2)]. In crystalline state the molecules of complexes were found to held by a moderate to strong intermolecular hydrogen bonds like CH⋯Cl and CH⋯O in both and OH⋯O, OH⋯Cl, NH⋯Cl in (S)-2∙H2O. In addition, there exists rare CH⋯Se and Se⋯O types of secondary bonding interactions between the molecules of (S)-1 and (S)-2∙H2O respectively. The interactions of ligands and complexes with CT-DNA have been studied by absorption, fluorescence and viscosity measurements. These determinants showed efficient binding interaction with DNA through ‘intercalation’ mode. The reduced Schiff base showed a higher binding capacity than the parent Schiff base. Further, the DNA binding affinity of complexes is higher than the corresponding ligands. The anticoagulant and non-haemolytic activities have also been investigated for these compounds. The human blood clotting time found to be enhanced from 150 to 200 sec in both PPP and PRP cases on coordination of ligands to palladium.

Nano-Schiff base Ligand:Synthesis, Characterization, DFT, and Antibacterial Evaluation of Some Complexes Derived From 4-(-4-methoxybenzylidene)amino) -Antipyrinyl with Glycine amino acid ligand

Synthesized from a new Neutral tridentate N2O Schiff base 4-(4- methoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one with amino acid ligand.forms stable complexes with transition metal ions such as Co (II), Ni (II), Cu (II), and Cd (II). The complexes were characterized on the basis of their Elemental analysis, molar conductivity, magnetic susceptibility data, IR, 1H-NMR, UV-Vis, XRD, Thermal Analysis (T.G, DTA, DSC), SEM, and Calculation Theoretical studies(DFT). Were used to characterize the complexes. The ligand acts as a tridentate chelating agent, According to physicochemical and spectral results, the ligand acts as a tridentate chelating agent. IR, UV-Vis., and magnetic susceptibility measurements all refer to an octahedral geometry. The general composition of all complexes [M(L)2] is (M=Co(II), Ni(II),Cu(II) and Cd(II), L=(K4-AMetB-Gly) The studies have led to the conclusion that, The coordination sites were established to be oxygen of the carboxyl COO- and two atoms nitrogen of the azomethine (CH=N) group based on the studies. The complexes non-electrolytic nature is verified by the lower conductivity data. The antibacterial activity of the ligand and its complexes was tested against Staphylococcus aureus, Escherichia coli, Klebsiella, and Psedomonas aeruginosa, it was found that these compounds show different activity of inhibition on the growth of the bacteria.

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Synthesis, characterization of ruthenium(II), nickel(II), palladium(II), and platinum(II) triphenylphosphine-based complexes bearing an ONS-donor chelating agent: Interaction with biomolecules, antioxidant, in vitro cytotoxic, apoptotic activity and cell cycle analysis

Four new transition metal complexes, [M(PPh3)(L)].CH3OH (M = Ni(II) (1), Pd(II) (2)) [Pt (PPh3)2(HL)]Cl (3) and [Ru(CO)(PPh3)2(L)] (4) (H2L = 2,4-dihydroxybenzaldehyde-S-methyldithiocarbazate, PPh3 = triphenylphosphine) have been synthesized and characterized by elemental analyses (C, H, N), FTIR, NMR (1H, 31P), ESI-MS and UV–visible spectroscopy. The molecular structure of (1) and (2) complexes was confirmed by single-crystal X-ray crystallography. It showed a distorted square planar geometry for both complexes around the metal center, and the H2L adopt a bi-negative tridentate chelating mode. The interaction with biomolecules viz., calf thymus DNA (ct DNA), yeast RNA (tRNA), and BSA (bovine serum albumin) was examined by both UV–visible and fluorescence spectroscopies. The antioxidant activity of all compounds is discussed on basis of DPPH• (2,2-diphenyl-1-picrylhydrazyl) scavenging activity and showed better antioxidant activity for complexes compared to the ligand. The in vitro cytotoxicity of the compounds was tested on human (breast cancer (MCF7), colon cancer (HCT116), liver cancer (HepG2), and normal lung fibroblast (WI38)) cell lines, showing that complex (1) the most potent against MCF7 and complex (4) against HCT116 cell lines based on IC50 and selective indices (SI) values. So, both complexes were chosen for further studies such as DNA fragmentation, cell apoptosis, and cell cycle analyses. Complex (1) induced MCF7 cell death by cellular apoptosis and arrest cells at S phase. Complex (4) induced HCT116 cell death predominantly by cellular necrosis and arrested cell division at G2/M phase due to DNA damage.

Synthesis, Characterization, DFT, and Antibacterial Evaluation of Some Complexes of Co (II), Ni(II), Cu(II), Zn (II), and Cd (II) with Schiff Ligand

A Synthesized from a new neutral tridentate N2O Schiff base 4-(4-hydroxy-2-methoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one with serine amino acid ligand forms stable complexes with many ions such as Co (II), Ni (II), Cu (II),Zn(II), and Cd (II). The complexes were recognized in term of their elemental analysis, 1H-NMR, UV-Vis, XRD, thermal analysis (T.G,DTA,DSC), and calculation theoretical studies (DFT) were used to characterize the complexes. The ligand acts like a tridentate chelating agent according to physicochemical and spectral results, the ligand acts like a tridentate chelating agent IR, UV-Vis, molar conductivity, and magnetic susceptibility measurements, all refer to an octahedral geometry the general composition of all complexes [M(L)2] is (M=Co(II), Ni(II). Cu(II),Zn(II), and Cd(II) L= (K4-AMetB-Ser). Concluded through studies that,the coordination sites were established to be oxygen of the carboxyl COO- and two atoms nitrogen of the azomethine (CH=N) group based on the studies. The complexes non-electrolytic nature is verified by the lower conductivity data. Finally the antibacterial activity of the ligand and its complexes was tested against Staphylococcus aureus, Escherichia coli, and Pseudomonas aereuguinosa it was found that these compounds show different activity of inhibition bacteria growth.

Albumin Conjugates of Thiosemicarbazone and Imidazole-2-thione Prochelators: Iron Coordination and Antiproliferative Activity.

The central role of iron in tumor progression and metastasis motivates the development of iron-binding approaches in cancer chemotherapy. Disulfide-based prochelators are reductively activated upon cellular uptake to liberate thiol chelators responsible for iron sequestration. Herein, a trimethyl thiosemicarbazone moiety and the imidazole-2-thione heterocycle are incorporated in this prochelator design. Iron binding of the corresponding tridentate chelators leads to the stabilization of a low-spin ferric center in 2 : 1 ligand-to-metal complexes. Native mass spectrometry experiments show that the prochelators form stable disulfide conjugates with bovine serum albumin, thus affording novel bioconjugate prochelator systems. Antiproliferative activities at sub-micromolar levels are recorded in a panel of breast, ovarian and colorectal cancer cells, along with significantly lower activity in normal fibroblasts.

Thiophene-Bipyridine Appended Diketopyrrolopyrrole Ligands and Platinum(II) Complexes.

Straightforward palladium(II) catalyzed direct cross-coupling reaction between decyl, (S)-2-methyl-butyl, and dodecyl N-substituted diketopyrrolopyrrole thiophene (DPPT), including a 3-methoxy-thiophene derivative, and 6-bromo-2,2'-bipyridine afforded a series of mono- and bis-bipyridine substituted DPPT ligands 1-3. Complexation reactions with PtCl2(DMSO)2 provided ortho-metalated platinum(II) complexes 1-Pt and 2-Pt, together with the N^N^O complex 3d-Pt(N^N^O) resulted from the O-Me activation of the intermediary complex 3d-Pt(N^N). The ligand 1b and the mononuclear complexes 1a-Pt and 1b-Pt have been structurally characterized by single crystal X-ray structure, evidencing the establishment of numerous intermolecular π-π interactions in the solid state. Moreover, in the crystal structure of the model complex DMTB-Pt(N^N^O) (DMTB = 3,4-dimethoxy-(2,2'-bipyridine)) the chelating tridentate N^N^O mode is clearly evidenced. The chiral ligand 1b and its mononuclear complex 1b-Pt do not show any CD signal in solution, but they are CD active in the solid state with bisignate bands in the low energy region, opposite in sign between the ligand and the complex, suggesting helical supramolecular arrangement of the dpp chromophore in the solid state. Photophysical investigations demonstrate that all of the ligands are fluorescent with high quantum yields, while the emission is quenched for the complexes, except partially in 3d-Pt(N^N), very likely through an intersystem crossing mechanism promoted by the heavy metal. Density functional theory calculations support the differences observed between the absorption properties of the ligands, ortho- and non-ortho-metalated complexes. The highly fluorescent bipyridine ligands reported herein open the way toward multifunctional transition metal complexes and their use in organic electronics.

Structures and magnetic properties of five lanthanide-radical complexes constructed by 8-methoxyquinoline substituted tridentate chelating nitronyl nitroxide radical

Five lanthanide complexes [Ln(hfac)3(8-MeOTQ-2-NIT)] constructed by a tridentate chelating 8-methoxyquinoline substituted nitronyl nitroxide radical (Ln ​= ​Gd (1), Tb (2), Dy (3), Ho (4), Er (5), hfac ​= ​hexafluoroacetylacetonate, 8-MeOTQ-2-NIT ​= ​2-(8-methoxyquinoline)-4,4,5,5- tetra-methylimidazoline-1-oxyl-3-oxide) have been successfully synthesized and characterized. The five complexes have similar mononuclear two-spin structures with one LnIII ion and one radical (Rad) in the molecules. And all LnⅢ ions are nine-coordinated in the geometry between mono-capped square antiprism (C4v) and a trigonal bipyramidal (D3h). Alternating current magnetic studies show that Tb and Dy complexes display frequency dependence of out of phase signals indicating the slow magnetic relaxation behavior of single molecular magnets. The ferromagnetic interactions in Gd/Tb-Rad complexes and the very weak antiferromagnetic interactions in Dy/Ho/Er-Rad complexes were estimated by the rough model combining lanthanide single ions approximation and molecular-field approximation.

Defluorination by ion exchange of SO42− on alumina surface: Adsorption mechanism and kinetics

Electrostatic and complexation effects have been considered as the primary adsorption mechanisms for defluorination using aluminum based materials, while the effect of ion exchange between anions and fluorine ion has been mostly ignored, although synthesized alumina materials usually contain a large amount of anions, such as SO42−, NO3−, and Cl−. In this study, the effect of anions exchanges and its key role on defluorination were systematically investigated for adsorption by aluminas loaded with various typical anions (SO42−, NO3− and Cl−). Experimental results showed that SO42-- loading alumina had the best defluorination performance (94.5 mg/g), much higher than NO3− (45.0 mg/g) and Cl− (19.1 mg/g). The contribution ratio of ion exchange between SO42− and F− was as high as 20–60% in all potential defluorination mechanisms. By using Density Functional Theory calculation, the detailed mechanism revealed that the ion exchange process was mainly driven by the tridentate chelation of SO42− which reduced the exchange energy (ΔF−−SO42− 4.8 eV). Our study clearly demonstrated that ion exchange between SO42− and F− is a critical mechanism in defluorination using aluminum-based materials and provides a potential alternative method to enhance the adsorption performance of modified alumina.

Synthesis, characterization and antimicrobial activity studies of new heterocyclic azo dye derived from 2-amino- 4,5- dimethyl thiazole with some metal ions

A novel heterocyclic azo dye ligand 2-[2- (4,5-Dimethyl thiazolyl)azo]- 4-methoxy phenol (DMeTAMP) was prepared by coupling reaction between diazonium salt produced from diazonited 2-amino- 4,5- dimethyl thiazole with 4 –methoxy phenol . The structures of the azo dye ligand and the metal complexes were characterized by elemental microanalyses (C.H.N.S), molar conductance, 1 H and 13 C- NMR, UV–Vis spectroscopy , FT-IR spectroscopy, magnetic susceptibility, thermal analysis (TGA), FESEM , mass spectra and XRD diffraction studies. The results appeared that prepared complexes offered [1:2] metal- ligand ratios and the ligand behaved as a tridentate chelating .The compounds were also tested for their bioactive property such as antibacterial and antifungal . The antioxidant activities of the ligand and Mn(II) complex were examined by using the DPPH radical scavenging method the compounds prove exhibited antioxidant properties of scavenging free radicals. Moreover, the anticancer properties of synthesized azo dye ligand and Mn(II) complexes were carried out against Colon cancer cell (CaCo 2 ) cell lines by MTT assay and results revealed that the prepared compounds exhibited good anticancer property and are very promising candidates for future applications in anti-tumor drugs . The finding indicated that these compounds have special significance in the field of medicine and pharmacy.

Synthesis, Crystal Structures of Gadolinium(III) and Erbium(III) Complexes Derived from Pyridine-2,6-Dicarboxylic Acid and Fluorescent Sensing of Picric Acid

Two new complexes of gadolinium(III) and erbium(III) with pyridine-2,6-dicarboxylic acid (H2Pydc),{Na3[Gd(Pydc)3]·2H2O}n (I) and [Er(HPydc)3]·10H2O (II), were prepared and their crystal structures were determined by X-ray crystallography (CIF files CCDC nos. 940633 (I) and 872068 (II)). The gadolinium atom in I is nine-coordinate (GdN3O6) and exhibits a tricapped trigonal prismatic geometry having 14 triangular faces. The Pydc ligand adopts chelating and, μ3- and μ5-bridging coordination modes. The 1D chains are further joined by Na atoms to generate a 3D coordination polymer. The structure is additionally stabilized by H-bonding. The Erbium polyhedron in II is also a tricapped trigonal prism (ErN3O6). The HPydc anions in II behave as tridentate chelating ligands. The complex molecules are connected to each other through hydrogen bonding interactions to form a three-dimensional network. Fluorescence titration experiments for complex II displayed highly sensitive fluorescence quenching efficiency of 98.3% against picric acid.

Optimization of signal amplification by reversible exchange for polarization of tridentate chelating bis[(2-pyridyl)alkyl]amine.

Signal amplification by reversible exchange (SABRE) is an effective NMR hyperpolarization technique for signal enhancement using para-hydrogen on iridium catalysts. To date, monodentate chelating nitrogen analogs have been predominantly used as substrates for SABRE because of the limited chelating sites of the Ir-catalyst with different molecular orientations. Herein, for the first time, the use of a tridentate chelating ligand (BPEA) containing pyridine moieties and a secondary amine as a SABRE substrate is demonstrated. For the optimization of the tridentate chelating ligand, alkyl chain lengths were varied with the optimization of the external magnetic field and concentrations of three different ligands. Because many chemically multidentate complexes present in nature have scarcely been studied as SABRE substrates, this optimized tridentate chelating ligand structure with the SABRE catalyst and its polarization transfer from para-hydrogen will broaden the scope of hyperpolarizable substrates and help in the investigation of chelating structures for future applications.

Zinc(II) complexes derived from 2-formylpyridine nicotinoyl hydrazone as organic blocker: Syntheses, crystal architectures, Hirshfeld surface analyses and DFT studies

In this work we report new discrete mononucler heteroleptic zinc(II) halido complexes of the type [Zn(Hal)2HL] (Hal = Cl, 1; Br, 2) and zinc(II) pseudohalido complex [Zn(NCS)2HL]·1.5MeOH (3·1.5MeOH) (HL = 2-formylpyridine nicotinoyl hydrazone). Single crystal X-ray diffraction revealed that in the structures of complexes 1–3, the Zn(II) metal atom is in a five-coordinated coordination environment and adopts a distorted square pyramidal chromophore, formed by one N2O tridentate chelator HL and two halides or thiocyanates, respectively. All complexes display a very similar molecular structure and complexes 1 and 2 are fully isostructural. Crystal packing of 1 and 2 is mainly dictated by the bifurcated N–H···Hal and linear C–H···Hal hydrogen bonds, yielding 1D polymeric chains, which additionally stabilized by intermolecular stacking interactions of the types ZnOCNN···ZnOCNN, ZnOCNN···ZnNCCN and 2-Py···3-Py. These 1D chains are interlinked into a 3D network through C–H···Hal interactions. Crystal packing of 3·1.5MeOH is constructed from centrosymmetric dimers formed through linear N–H···O and O–H···N hydrogen bonds, yielding a hydrogen bonded synthon of motif R44(16). These dimers are interlinked trough the C–S···ZnNCCN interactions, yielding 1D polymeric chains, which, in turn, are interlinked through the C–H···O bonds, and ZnNCCN···3-Py and 3-Py···3-Py stacking interactions into a 3D framework. Hirshfeld surface analysis, employed to gain additional insight into interactions responsible for the packing of complexes, and quantitative examination of 2D fingerprint plots revealed that the most important factors in the crystal packing are H···Hal and and H···H contacts in 1 and 2, and H···H, H···N, H···C and H···S contacts in 3, further supported by C···C contacts. Density function theory (DFT) calculations were performed to gather more information into structure and bonding since they play an important role in the construction of 3D supramolecular frameworks.

Systematic DFT Studies on Binary Pseudo-tetrahedral Zintl Anions: Relative Stabilities and Reactivities towards Protons, Trimethylsilyl Groups, and Iron Complex Fragments.

Binary pseudo‐tetrahedral Zintl anions composed of (semi)metal atoms of the p‐block elements have proven to be excellent starting materials for the synthesis of a variety of heterometallic and intermetalloid transition metal–main group metal cluster anions. However, only ten of the theoretically possible 48 anions have been experimentally accessed to date as isolable salts. This brings up the question whether the other species are generally not achievable, or whether synthetic chemists just have not succeeded in their preparation so far. To contribute to a possible answer to this question, global minimum structures were calculated for all anions of the type (TrTt3)5−, (TrPn3)2−, and (Tt2Pn2)2−, comprising elements of periods 3 to 6 (Tr: triel, Al⋅⋅⋅Tl; Tt: tetrel, Si⋅⋅⋅Pb; Pn: pnictogen, P⋅⋅⋅Bi). By analyzing the computational results, a concept was developed to predict which of the yet missing anions should be synthesizable and why. Additionally, the results of an electrophilic attack by protons or trimethylsilyl groups or a nucleophilic attack by transition metal complex fragments are described. The latter yields butterfly‐like structures that can be viewed as a new form of adaptable tridentate chelating ligands.

Homochiral lanthanide metal–organic frameworks based on amino acid-functionalized terpyridyl ligand: synthesis, structure determination, and optical properties

Utilizing chiral terpyridine derivative ligand (S)-2-((4-([2,2′:6′,2″-terpyridin]-4′-yl)benzyl)amino)propanoic acid (HL) and corresponding Ln(NO3)3, five new isostructural homochiral lanthanide metal–organic frameworks [{[Ln2(HL)2(NO3)4(H2O)4]·NO3·Cl·7H2O}n [Ln = Nd (1), Pr (2), Sm (3), Eu (4), Tb (5)] comprised of left- and right-handed helical chains were solvothermally synthesized. Various means such as IR spectroscopy, elemental analysis, powder X-ray diffraction, and thermal analysis were used to characterize the compounds, wherein compounds 1 and 2 were crystallographically characterized. In the structure of representative 1, zwitterionic ligands HL bridge Nd3+ ions through the monodentate coordination of their carboxylates and the tridentate chelation of their terpyridyls, leading to the formation of left- and right-handed helical chains. The adjacent left- and right-handed helical chains are further connected into a 2D helical layer through interchain hydrogen-bonding interactions, and these layers stack up through interlayer π⋯π interactions to form an interesting three-dimensional homochiral cationic architecture with one-dimensional triangular channels wherein guests anions and water are trapped. The compounds were systematically studied with respect to their solid-state optical properties, including CD spectra, and nonlinear optical and luminescent properties, and the results showed that the sensitization effect of HL ligand on the emission of Tb3+ and Eu3+ was better than that of Sm3+.

Ligand directed synthesis of a unprecedented tetragonalbipyramidal copper (II) complex and its antibacterial activity and catalytic role in oxidative dimerisation of 2‐aminophenol

In pursuit of the significant contribution of copper ion in different biological processes, this research work describes the synthesis, X‐ray structure, Hirshfeld surface analysis, oxidative dimerization of 2‐aminophenol and antibacterial activity of a newly designed copper (II)‐Schiff base complex, [Cu(L)2] (1), [Schiff base (HL) = 2‐(2‐methoxybenzylideneamino)phenol]. X‐ray structural analysis of 1 reveals that the Cu (II) complex crystallizes in a cubic crystal system with Ia‐3d space group. The Cu (II) centre adopts an unprecedented tetragonal bipyramidal geometry in its crystalline phase. The Schiff base behaves as a tridentate chelator and forms an innermetallic chelate of first order with Cu (II) ion. The copper (II) complex has been tested in the bio‐mimics of phenaxozinone synthase activity in acetonitrile and exhibits good catalytic activity as evident from high turnover number, 536.4 h−1. Electrochemical analysis exhibits the appearance of two additional peaks at −0.15 and 0.46 V for Cu (II) complex in presence of 2‐AP and suggests the development of AP−/AP•− and AP•−/IQ redox couples in solution, respectively. The presence of iminobenzosemiquinone radical at g = 2.057 in the reaction mixture was confirmed by electron paramagnetic resonance and may be considered the driving force for the oxidative dimerisation of 2‐AP. The existence of a peak at m/z 624.81 for Cu (II) complex in presence of 2‐AP in electrospray ionization mass spectrum ensures that the catalytic oxidation proceeds through enzyme‐substrate adduct formation. The copper (II) complex exhibits potential antibacterial properties against few pathogenic bacterial species like Staphylococcus aureus, Enterococcus and Klebsiella pneumonia and scanning electron microscope studies consolidates that destruction of bacterial cell membrane accounts on the development of antibacterial activity.

Directionally Selective Polyhalide Molecular Glue for Stable Inverted Perovskite Solar Cells

The fundamental instability of hybrid perovskite solar cells originates from the considerable halide vacancies. Furthermore, the local roles of halide vacancies between grain boundaries and grain bulk generally conflict, thus inhibiting complete passivation. To overcome this obstacle, a rational polyhalide ligand, di‐(2‐picolyl)amine triiodide, is designed as a molecular “glue” to achieve comprehensive passivation. Unlike a monohalide ligand, this ligand has multiple iodide ions and a quasiplanar tridentate chelation capability, contributing to directional passivation along the grain boundaries and overall passivation throughout the grain bulk. Using this molecular glue passivation, the best inverted solar cell yields an efficiency of 20.02%. Moreover, the relative stability of this cell in ambient air (≈40% humidity, 800 h aging) and under light‐soaking conditions (500 h aging) is profoundly enhanced by 33.33% and 22.26%, respectively. Herein, important insights into the design of passivating molecules to achieve low‐defect perovskites toward the development of multifunctional devices are provided.

Effect of the triphenylphosphonium cation on the biological properties of new rhenium and technetium-99m fac-[M(CO)3(NSN)]±-type complexes: Synthesis, structural characterization, in vitro and in vivo studies

Triphenylphosphonium (TPP) cations have been used for the development of tumor or myocardial diagnostic radiopharmaceuticals. In this work, the development of new [99mTc][Tc(CO)3(N,S,N)]+ complexes of the (N,S,N) tridentate chelator benzimidazol-2-yl-methylthioethylamine (L), and its triphenylphosphonium (TPP) cation derivative L-TPP is described. The TPP-moiety was conjugated at the Nτ-benzimidazol position of L. The reaction of the chelators L and L-TPP with a suitable precursor [Re(sol)3(CO)3]+ yielded single products of ReL+ and ReL-TPP2+. The complexes were characterized by spectroscopic methods and furthermore the structure of ReL was elucidated by X-ray crystallography. The respective 99mTc-radiotracers were synthesized in high yield, their lipophilicity was measured and both exhibited high stability in cysteine, histidine solutions as well as in rat plasma. The in vitro cell studies in human erythroleukemia K-562 and glioblastoma U-87MG tumor cells showed that the tracer 99mTcL+ exhibited significantly higher cellular uptake, while 99mTcL-TPP2+ exhibited significantly higher mitochondrial accumulation. The tracers 99mTcL+ and 99mTcL-TPP2+ exhibited fast blood elimination and excretion via the hepatobiliary and the renal routes after intravenous administration in healthy mice. Tracer 99mTcL+ exhibited higher myocardial uptake and renal excretion, while 99mTcL-TPP2+ exhibited primarily hepatobiliary excretion. These data confirm the high mitochondrial accumulation of 99mTcL-TPP2+ in vitro and show its potential as a candidate for tumor imaging.

Synthesis and characterization of Al(III) complex with paracetamol

The complex of Al (111) with paracetamol have synthesized and characterized using UV–Vis, Infrared spectroscopies and melting point. The ligand has been found to behave as tridentate chelating agents. Paracetamol complex coordinate through the carboxylate oxygen, phenolate oxygen atom, and amine group. The complex solubility was evaluated for several solvents and it was found the compound was more soluble in DMSO. Job’s method of continuous variation suggested 1 : 2 metals to ligand stoichiometry for paracetamol complex

Bis{2,6-bis[(E)-(4-fluorobenzylimino)methyl]pyridine}nickel(II) dinitrate dihydrate

In the title hydrated salt, [Ni(C21H17F2N3)2](NO3)2·2H2O, the central NiII ion is coordinated by six N atoms from two tridentate chelating 2,6-bis[(E)-(4-fluorobenzylimino)methyl]pyridine ligands. While the central NiII ion is six-coordinate, its environment is distorted from an octahedral structure because of the unequal Ni—N distances. The Ni—N bond lengths vary from 1.8642 (14) to 2.2131 (15) Å, while the N—Ni—N angles range from 79.98 (6) to 104.44 (6)°. Three coordinating sites of each chelating agent are almost coplanar with respect to the pyridine ring, and two pyridine moieties are perpendicular to each other. Two non-coordinating nitrate anions within the asymmetric unit balance the charges of the central metal ion, and are linked with two crystal water molecules, forming a water–nitrate cyclic tetrameric unit [O...O = 2.813 (2) to 3.062 (2) Å]. In an isolated molecule, the fluorophenyl rings of one ligand are stacked with the central ring of the other ligand via π–π interactions, with the closest centroid-to-plane distances being 3.359 (6), 3.408 (5), 3.757 (6) and 3.659 (5) Å.