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► Complexes bearing heteroscorpionate derived from bis(pyrazolyl)methane moieties. ► Overview of the catalytic activity of this type of metal complexes. ► These complexes can act as ...efficient catalyst in several catalytic processes.
This review covers studies related to the design of ligands, synthetic pathways and catalytic processes of some families of metal complexes that contain heteroscorpionate ligands based on bis(pyrazol-1-yl)methane moieties.
•12 new heteroscorpionate ligands with chromone fragment have been synthesized.•Ni(II), Co(II) and Pd(II) complexes with these ligands have been synthesized and characterized.•Ni complex exhibits ...higher cytotoxicity against breast cancer cells MCF7.
Synthetic derivatives of flavonoids are a promising class of biologically active compounds. Here we report a family of (chromon-3-yl)-bis(3,5-dimethylpyrazol-1-yl)methanes bearing various substituents in chromone fragment. They have been studied for the antioxidant activity and spectra of their biological activity have been predicted. New Ni(II), Co(II) and Pd(II) complexes, supported by 3-bis(3,5-dimethylpyrazol-1-yl)methyl-6-fluoro-chromen-4-one, have been synthesized and characterized using 1H NMR, high-resolution MALDI-TOF spectrometry and elemental analyses. The molecular structures of 3-bis(3,5-dimethylpyrazol-1-yl)methyl-chromen-4-one 1, 3-bis(3,5-dimethylpyrazol-1-yl)methyl-6‑chloro-chromen-4-one 7 and Co dichloride complex with 3-bis(3,5-dimethylpyrazol-1-yl)methyl-6-fluoro-chromen-4-one 15 have been determined using single crystal X-ray diffraction studies. The cytotoxic activity of metal complexes and the ligand 1 has been studied on 4 cell lines of different histological origin. It has been observed that Ni complex exhibits higher cytotoxicity against breast cancer cells MCF7 and Co complex has almost the same effect on the growth of all studied tumor cells.
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The C-centered bis(imidazol-1-yl)methane-based heteroscorpionate metal(II) complexes of the type M(L1−3)Cl (1–9), where M = Mn(II), Ni(II) or Cu(II) have been synthesized using the heteroscorpionate ...ligands, (2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL1), (4-diethylamino-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL2) and (5-bromo-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL3). The spectral and theoretical studies suggested tetrahedral geometry for manganese(II) and nickel(II) complexes, and square-planar geometry for copper(II) complexes. The antimicrobial activity of the complexes was evaluated against two Gram (–ve) (Shigella dysenteriae and Vibrio cholerae) and two Gram (+ve) (Bacillus cereus and Streptococcus faecalis) bacterial, and three fungal (Candida albicans, Candida glabrata and Candida krusei) strains. The antioxidant activity of the ligands and their nickel(II) and copper(II) complexes were determined by ABTS, DPPH and H2O2 free radical scavenging assays. In vitro cytotoxicity activity of the ligands and their nickel(II) and copper(II) complexes were tested against human breast adenocarcinoma (MCF-7), cervical (HeLa) and lung (A549) cancerous and normal human dermal fibroblast (NHDF) cell lines by MTT reduction assay. The copper(II) complex 8 exhibit higher cytotoxicity activity than the other complexes against all the tested cancer cell lines. Molecular docking studies of the complexes were also performed with c-Met tyrosine kinase receptor to determine the possible binding mode and predominant binding interactions.
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•Nine heteroscorpionate metal(II) complexes were synthesized and characterized.•The structures of the complexes were investigated by DFT calculations.•The copper(II) complexes exhibited higher biological activity.•The molecular docking study was performed with the c-Met tyrosine kinase receptor.
In this brief review we focus on a few examples of how a family of homo‐ and heteroscorpionate ligands allow us to examine how changes in reactivity, structure, or physical/chemical properties around ...biologically interesting N2X coordinated metal centers vary as a function of donor atom, charge, hydrophobicity, hydrogen bonding, etc., in a way previously unavailable. Such a family of ligands is the bioinorganic chemists answer to site‐directed mutagenesis. Here we focus on two bioinorganic examples i.e. models for molybdoenzymes and zinc metalloproteins.
A family of heteroscorpionate ligands of the form N2X is presented where X can be interchanged between a thiolate sulfur, a pyrazole nitrogen, or a carboxylate, alkoxy or phenoxy oxygen in a series of isostructural isoelectronic metal complexes gives the bioinorganic chemist the ability to do the equivalent of “site directed mutagenesis”.
The modular synthesis of the heteroscorpionate core is explored as a tool for the rapid development of ruthenium-based therapeutic agents. Starting with a series of structurally diverse alcohol-NN ...ligands, a family of heteroscorpionate-based ruthenium derivatives was synthesized, characterized, and evaluated as an alternative to platinum therapy for breast cancer therapy. In vitro, the antitumoral activity of the novel derivatives was assessed in a series of breast cancer cell lines using UNICAM-1 and cisplatin as metallodrug control. Through this approach, a bimetallic heteroscorpionate-based metallodrug (RUSCO-2) was identified as the lead compound of the series with an IC50 value range as low as 3–5 μM. Notably, RUSCO-2 was found to be highly cytotoxic in TNBC cell lines, suggesting a mode of action independent of the receptor status of the cells. As a proof of concept and taking advantage of the luminescent properties of one of the complexes obtained, uptake was monitored in human breast cancer MCF7 cell lines by fluorescence lifetime imaging microscopy (FLIM) to reveal that the compound is evenly distributed in the cytoplasm and that the incorporation of the heteroscorpionate ligand protects it from aqueous processes, conversion in another entity, or the loss of the chloride group. Finally, ROS studies were conducted, lipophilicity was estimated, the chloride/water exchange was studied, and stability studies in simulated biological media were carried out to propose structure-activity relationships.
The versatility of the coordination mode of the heteroscorpionate ligands and their easily tunable core provide exceptional and modulable steric and electronic features required for the rational design of new anticancer ruthenium metallodrugs. Display omitted
•Metallodrugs are a well-established group of chemotherapeutic agents for the treatment of cancer.•Heteroscorpionate ligands act as auxiliary scaffolds for the generation of ruthenium metallodrugs.•RUSCO-2 showed higher cytotoxicity than cisplatin against TNBC cells.•Heteroscorpionate ruthenium derivative is evenly distributed in the cytoplasm.
Tricarbonylmanganese(I) complexes of the heteroscorpionate ligand 3,3-bis(3,5-dimethylpyrazol-1-yl)propionate (bpzp) and the tris-imidazole complex fac-Mn(CO)3(HIm)3Br were prepared. These and the ...literature-know tricarbonyl complexes based on bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza), bis(pyrazol-1-yl)acetate (bpza), 3,3-bis(3,5-dimethylpyrazol-1-yl)propionate (bdmpzp) and fac-MnBr(CO)3(Hpz)2 were tested for their potential to act as photoactivable CO-releasing molecules (PhotoCORMs) by the UV/Vis spectroscopy based myoglobin assay. The manganese(I) complexes of the monodentate imidazole and pyrazole ligands lack stability in solution and show fast CO release already in the dark. In the four heteroscorpionate complexes, the substitution pattern and the chain length of the carboxylate moiety have a pronounced influence on the stability in solution and the CO release properties.
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(η6-p-cymene)RuI22 (1) was reacted with the heteroscorpionate ligands, bis(pyrazolyl)acetic acid (BPAH) or bis(3,5-dimethylpyrazoly)acetic acid (BMPAH), in the presence of potassium carbonate under ...various conditions to yield cationic Ru(II) complexes: (BPA)Ru(cymene)I (2), (BMPA)Ru(cymene)I (3), (BPA)Ru(NCMe)3I (4), and (BMPA)Ru(NCMe)3)I (5). The piano-stool, η6-cymene ruthenium complexes (2 and 3) are isolated when the reaction was conducted at room temperature, whereas the tris-acetonitrile ruthenium(II) complexes were isolated at elevated reaction temperatures. The iodide anion of 4 or 5 was easily replaced with tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (BArF′) by reaction with silver tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (AgBArF′) to yield (BPA)Ru(NCMe)3BArF′ (6) and (BMPA)Ru(NCMe)3)BArF′ (7), which demonstrate improved solubility in organic solvents as compared to 4 and 5. The acetonitrile ligands cis to the carboxylate group in 4 and 5 were significantly more labile than the trans acetonitrile ligand. The rate of acetonitrile dissociation for 4 and 5 was found to be statistically equivalent. These complexes were characterized by 1H, 13C, 19F nuclear magnetic resonance spectroscopy, infrared spectroscopy, and elemental analyses. Compounds 2, 4, 5, and 7 were also characterized by single crystal X-ray crystallography.
Tris-acetonitrile ruthenium(II) complexes supported by heteroscorpionates ligands have been synthesized and characterized, including single crystal X-ray crystallography. Display omitted
•Synthesis of tris-acetonitrile heteroscorpionate ruthenium complexes.•Examination of the trans influence on the rate of acetonitrile dissociation.•New method for preparing p-cymene-heteroscorpionate ruthenium complexes.
A new and easy route to prepare “a la carte” bis(1,2,3‐triazol‐1‐yl)methane compounds, namely bmtzm (1), bptzm (2), bttzm (3), bmtzpm (4), bptzpm (5), bttzpm (6), bmtzom (7), bptzom (8) and bttzom ...(9), with different functional groups is reported. The compounds were prepared by reaction between readily accessible alkynes and geminal diazides in a double Cu‐catalyzed azide‐alkyne cycloaddition (CuAAC) reaction. These materials were used as starting materials for the synthesis of more elaborate compounds. Thus, the preparation of new bis(1,2,3‐triazol‐1‐yl)methane‐based heteroscorpionate neutral precursors pbptztamH (10), pbttztamH (11), (S)‐mbptzamH (12) and (S)‐mbttzamH (13) and a dinuclear zinc complex, Zn{pbptztam}Et2 (14), was achieved. The structures of the compounds were determined by spectroscopic methods, and the X‐ray crystal structures of compounds 2, 3, 7, 8, 9 and 14 were established.
A new approach for the preparation of diverse and complex bis(1,2,3‐triazol‐1‐yl)methane derivatives is reported. This process exhibits excellent compatibility with different functionalized gem‐diazides and different substituted terminal alkynes.
The dimeric amide lanthanum complex {
CP(O)Ph
2
LaN(SiMe
3
)
2
(µ
2
-OP(O)Ph
2
)}
2
(Pzl
Me2
is 3,5-dimethylpyrazole) bearing the
N
,
N
,
O
-tridentate heteroscorpionate ligand is synthesized. As ...found by X-ray diffraction (XRD) (CIF file CCDC no. 2212274), the complex is binuclear and its lanthanum ions are linked by two bridging monoanionic diphenyl phosphinate ligands. The synthesized lanthanum complex demonstrates a high catalytic activity in the polymerization with ring opening of
rac
-lactide and ε-caprolactone providing the quantitative conversion of 500 equivalents of the monomer to the polymer at room temperature within 360–720 min for
rac
-lactide and 10–30 min for ε-caprolactone. The formed polylactides are characterized by the atactic microstructure (
P
r
= 0.54–0.56) and polydispersity indices (PDI) of 1.6–2.5, whereas for polycaprolactone PDI = 2.1–2.8.
The effects of stereochemistry (cis and trans) on OAT between heteroscorpionate dioxo Mo(VI) complexes and triphenylphosphine are examined. Display omitted
•Heteroscorpionate complexes containing an ...interchangeable third heteroatom donor have been utilized for the systematic investigation of oxygen atom transfer (OAT) reactivity.•The detection of phosphoryl intermediates and products in the reaction pathway were probed by UV–Vis, mass spectrometry, and 31P NMR spectroscopy.•The OAT reactivity of the cis isomer of (L10O)MoO2Cl demonstrated a dramatic solvent dependence and is much lower than for the trans complex.•The catalytic oxidation of PPh3 to OPPh3 by trans-(L10O)MoO2Cl and cis-(L3S)MoO2Cl complexes using DMSO as an oxygen donor was monitored by 31P NMR.
Heteroscorpionate-based (L10O)MoO2Cl and (L3S)MoO2Cl complexes containing an interchangeable third heteroatom donor have been utilized for the systematic investigation of oxygen atom transfer (OAT) reactivity. The detection of phosphoryl intermediates and products in the reaction pathway were probed by UV–Vis, mass spectrometry, and 31P NMR spectroscopy. The OAT reactivity of the metal complexes toward PPh3 were monitored by UV–Vis spectroscopy under pseudo-first order conditions. The sterically encumbered (L10O) ligand gives rise to isolable trans and cis isomers of (L10O)MoO2Cl allowing investigation into the role of geometry on OAT reactivity. The OAT reactivity of the cis isomer of (L10O)MoO2Cl demonstrated a dramatic solvent dependence, in which the reaction proceeded at a measureable rate only in pyridine. However, the trans counterpart reacted in all solvents and at much faster rates. The catalytic oxidation of PPh3 to OPPh3 by trans-(L10O)MoO2Cl and cis-(L3S)MoO2Cl complexes using DMSO as an oxygen donor was monitored by 31P NMR in DMF at 30°C with rates, kcat=4.26×10−5s−1 and 5.28×10−5s−1, respectively.
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