Extension and functionalization of an encapsulating macrobicyclic ligand using palladium-catalyzed Suzuki-Miyaura and Sonogashira reactions of iron(ii) dihalogenoclathrochelates with inherent halogen substituents.

A new approach for performing Suzuki-Miyaura and Sonogashira reactions of iron(ii) dihalogenoclathrochelates, optimizing their reaction conditions (such as temperature, solvent and a palladium-containing catalyst) and the nature of other reagents (such as arylboron components) is elaborated. These palladium-catalyzed reactions are very sensitive to the nature of the macrobicyclic substrates. The reactivity of the leaving halogen atoms correlates with their ability to undergo an oxidative addition, decreasing in the order: I > Br > Cl, and iron(ii) diiodoclathrochelate underwent these C-C cross-couplings under their "classical" conditions.

Induced chirality of cage metal complexes switched by their supramolecular and covalent binding.

An ability of the ribbed-functionalized iron(ii) clathrochelates to induce a CD output in interactions with a protein, covalent bonding or supramolecular interactions with a low-molecular-weight chiral inductor, was discovered. The interactions of CD inactive, carboxyl-terminated iron(ii) clathrochelates with serum albumin induced their molecular asymmetry, causing an appearance of strong CD signals in the range of 350-600 nm, whereas methyl ester and amide clathrochelate derivatives remained almost CD inactive. The CD spectra of carboxyl-terminated clathrochelates on supramolecular interactions or covalent bonding with (R)-(+)-1-phenylethylamine gave a substantially lower CD output than with albumin, affected by both the solvent polarity and the isomerism of clathrochelate's ribbed substituents.

A Trigonal Prismatic Mononuclear Cobalt(II) Complex Showing Single-Molecule Magnet Behavior.

Single-molecule magnets (SMMs) with one transition-metal ion often rely on unusual geometry as a source of magnetically anisotropic ground state. Here we report a cobalt(II) cage complex with a trigonal prism geometry showing single ion magnet behavior with very high Orbach relaxation barrier of 152 cm(-1). This, to our knowledge, is the largest reported relaxation barrier for a cobalt-based mononuclear SMM.

Molecular design of cage iron(II) and cobalt(II,III) complexes with a second fluorine-enriched superhydrophobic shell.

Pentafluorophenylboron-capped iron and cobalt(II) hexachloroclathrochelate precursors were obtained by the one-pot template condensation of dichloroglyoxime with pentafluorophenylboronic acid on iron and cobalt(II) ions under vigorous reaction conditions in trifluoroacetic acid media. These reactive precursors easily undergo nucleophilic substitution with (per)fluoroarylthiolate anions, giving (per)fluoroarylsulfide macrobicyclic complexes with encapsulated iron and cobalt(II) ions; nucleophilic substitution of the cobalt(II) hexachloroclathrochelate precursor with a pentafluorophenylsulfide anion gave the target hexasulfide monoclathrochelate and the mixed-valence Co(III)Co(II)Co(III) bis-clathrochelate as a side product. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, (57)Fe Mössbauer (for the X-rayed iron complexes), (1)H, (11)B, (13)C and (19)F NMR spectroscopies and by X-ray diffraction; their redox and electrocatalytic behaviors were studied using cyclic voltammetry and gas chromatography.

Copper(I)- and copper(0)-promoted homocoupling and homocoupling-hydrodehalogenation reactions of dihalogenoclathrochelate precursors for C-C conjugated iron(II) bis-cage complexes.

Iron(II) dibromo- and diiodoclathrochelates undergo copper(I)-promoted reductive homocoupling in HMPA at 70-80 °C leading to C-C conjugated dibromo- and diiodo-bis-clathrochelates in high yields. Under the same conditions, their dichloroclathrochelate analog does not undergo the same homocoupling reaction, so the target dichloro-bis-cage product was obtained in high yield via dimerization of its heterodihalogenide iodochloromonomacrobicyclic precursor. The use of NMP as a solvent at 120-140 °C gave the mixture of bis-clathrochelates resulting from a tandem homocoupling-hydrodehalogenation reaction: the initial acetonitrile copper(I) solvato-complex at a high temperature underwent re-solvatation and disproportionation leading to Cu(II) ions and nano-copper, which promoted the hydrodehalogenation process even at room temperature.

Clathrochelates meet phosphorus: thiophosphorylation of Fe(II) dichloroclathrochelate precursor, synthesis of N,S-donor macrobicyclic ligands and their Pd(II) complexes as potent catalysts of Suzuki cross-coupling reaction.

Nucleophilic substitution of an iron(ii) dichloroclathrochelate with diphenylphosphine sulfide under PTC afforded a monophosphorylated cage complex. This precursor undergoes further nucleophilic substitution with mono- and diamines giving P,N-substituted mono- and bis-clathrochelates; those with thiophosphoryl and pyridyl groups were used as N,S-donor macrobicyclic ligands toward the palladium(ii) ion. In the resulting Pd,Fe-binuclear 1 : 1 complexes, the clathrochelate moieties retain the geometry, characteristic of low-spin iron(ii) complexes, with a minor distortion caused by intramolecular interactions.

A Mononuclear Mn(II) Pseudoclathrochelate Complex Studied by Multi-Frequency Electron-Paramagnetic-Resonance Spectroscopy.

Knowledge of the correlation between structural and spectroscopic properties of transition-metal complexes is essential to deepen the understanding of their role in catalysis, molecular magnetism, and biological inorganic chemistry. It provides topological and, sometimes, functional insight with respect to the active site properties of metalloproteins. The electronic structure of a high-spin mononuclear Mn(II) pseudoclathrochelate complex has been investigated by electron-paramagnetic-resonance (EPR) spectroscopy at 9.

Study of anti-fibrillogenic activity of iron(II) clathrochelates.

The macrocyclic compounds mono- and bis-iron(II) clathrochelates were firstly studied as potential anti-fibrillogenic agents using fluorescent inhibitory assay, atomic force microscopy and flow cytometry. It is shown that presence of the clathrochelates leads to the change in kinetics of insulin fibrillization reaction and reduces the amount of formed fibrils (up to 70%). The nature of ribbed substituent could determine the activity of clathrochelates-the higher inhibitory effect is observed for compounds containing carboxybenzenesulfide groups, while the inhibitory properties only slightly depend on the size of complex species.

Chloride ion-aided self-assembly of pseudoclathrochelate metal tris-pyrazoloximates.

Chloride ion-aided one-pot template self-assembly of a mixed pyrazoloxime ligand with phenylboronic acid on a corresponding metal(II) ion as a matrix afforded the first boron-capped zinc, cobalt, iron, and manganese pseudoclathrochelate tris-pyrazoloximates. The presence of a pseudocross-linking hydrogen-bonded chloride ion is critical for their formation, as the same chloride-capped complexes were isolated even in the presence of large excesses of bromide and iodide ions. As revealed by X-ray diffraction, all complexes are capped with a chloride ion via three N-H···Cl hydrogen bonds that stabilize their pseudomacrobicyclic frameworks.

Apically linked iron(II) α-dioximate and α-oximehydrazonate bis-clathrochelates: synthesis, structure and electrocatalytic properties.

Iron(II) α-oximehydrazonate and α-dioximate bis-clathrochelates with apical hydrocarbon linkers were obtained by template condensation on an iron(II) ion followed by H(+)-catalyzed macrobicyclization of the bis-semiclathrochelate precursor with formaldehyde and triethyl orthoformate, and by transmetallation of the triethylantimony-containing clathrochelate precursor with diboron-containing bifunctional Lewis acids, respectively. The geometry of the para-phenylenediboron-capped iron(II) bis-clathrochelate studied by single-crystal X-ray diffraction is intermediate between a trigonal prism and a trigonal antiprism with a distortion angle of 20.4°; the rigidity of its C6H4 linker results in the presence of the expected three-fold pseudo-rotational B···Fe···B···B···Fe···B axis and a staggered conformation of the cyclohexane-containing chelate moieties.

Size matters, so does shape: Inhibition of transcription of T7 RNA polymerase by iron(II) clathrochelates.

Coordination and organoelement compounds are rarely proposed as the drug candidates despite their vast potential in the area owing to their strictly controlled geometry and rather extensive surface. This is the first example of the inhibition of transcription in the system of T7 RNA polymerase by cage metal complexes. Their IC50 values reach as low as the nanomolar range, placing them among the most potent metal-based transcription inhibitors.

Interaction of the iron(II) cage complexes with proteins: protein fluorescence quenching study.

Interaction of the iron(II) mono- and bis-clathrochelates with bovine serum albumin (BSA), β-lactoglobulin, lysozyme and insulin was studied by the steady-state and time-resolved fluorescent spectroscopies. These cage complexes do not make significant impact on fluorescent properties of β-lactoglobulin, lysozyme and insulin. At the same time, the monoclathrochelates strongly quench a fluorescence intensity of BSA and substantially decrease its excited state lifetime due to their binding to this protein.

Insight into the electronic structure, optical properties, and redox behavior of the hybrid phthalocyaninoclathrochelates from experimental and density functional theory approaches.

An insight into the electronic structure of several hafnium(IV), zirconium(IV), and lutetium(III) phthalocyaninoclathrochelates has been discussed on the basis of experimental UV-vis, MCD, electro- and spectroelectrochemical data as well as density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. On the basis of UV-vis and MCD spectroscopy as well as theoretical predictions, it was concluded that the electronic structure of the phthalocyninoclathrochelates can be described in the first approximation as a superposition of the weakly interacting phthalocyanine and clathrochelate substituents. Spectroelectrochemical data and DFT calculations clearly confirm that the highest occupied molecular orbital (HOMO) in all tested complexes is localized on the phthalocyanine ligand.

Synthesis and structure of the first clathrochelate iron(II) tris-dioximates with inherent nitrile substituent(s) and new dehalogenation--reduction reaction at a quasi-aromatic macrobicyclic framework.

Monoribbed-substituted mono- and dicyano-functionalized iron(II) macrobicycles were obtained for the first time by the reaction of iron(II) diiodoclathrochelate precursor with copper(I) cyanide-triphenylphosphine complex under mild conditions. The target dinitrile clathrochelate is a minor product of this reaction, whereas the major product contains only one cyano group. The clathrochelates obtained were characterized using elemental analysis, (1)H and (13)C{(1)H} NMR, IR and UV-vis spectroscopy, MALDI-TOF spectrometry and X-ray diffraction crystallography.

Efficient electrocatalytic hydrogen production from H+ ions using specially designed boron-capped cobalt clathrochelates.

Specially designed hexachlorine-containing cobalt(II) tris-dioximate clathrochelates were found to efficiently electrocatalyze the production of molecular hydrogen from H(+) ions without the overpotential of this process.

Interaction of dichloride iron(II) clathrochelate with dimercaptomaleodinitrile: synthesis of the precursor monoribbed-functionalized phthalocyaninoclathrochelates and the unexpected formation of a new thiophene-containing heterocyclic system in the ribbed chelate fragment of the clathrochelate framework.

Clathrochelate iron(II) FeBd 2(S2C2(CN)2Gm)(BF)2 tris-dioximate with a ribbed vic-dinitrile fragment was synthesized as a precursor of the monoribbed-functionalized hybrid phthalocyaninoclathrochelates by nucleophilic substitution of the vic-dichloride FeBd2(Cl2Gm)(BF)2 clathrochelate (1) with the potassium salt of dimercaptomaleodinitrile. Reaction of nitromethane with this salt was followed by the condensation of the reaction products with 1 to yield the clathrochelate with an annulated previously unknown thiazinothiophene heterocyclic system in the ribbed fragment. Both complexes were characterized on the basis of elemental analysis; MALDI-TOF mass spectrometry; IR, UV-vis, (57)Fe Mössbauer, and NMR spectroscopies; and X-ray crystallography.

Ditopic macropolycyclic complexes: synthesis of hybrid phthalocyaninoclathrochelates.

A remetalation (a capping group exchange) reaction of the boronantimony-capped iron(II) clathrochelates with zirconium and hafnium(IV) phthalocyanines in CH2Cl2/CH3OH medium afforded the hybrid phthalocyaninoclathrochelates in a practically quantitative yield. The complexes obtained have been characterized both on the basis of elemental analysis, PD mass spectrometry, IR, UV-vis, 57Fe Mössbauer, and NMR spectroscopies, and crystallographically. An encapsulated iron(II) ion in an intermediate between a trigonal-prismatic and a trigonal-antiprismatic environment of six nitrogen atoms of the macrobicyclic ligand was found to be in a low-spin state.

Synthesis and DNA binding properties of dioxime-peptide nucleic acids.

Peptide nucleic acids (PNAs) C- or N-modified with dioxime ligands were prepared by solid-phase synthesis using iron(II)-clathrochelates as protected dioxime building blocks. These PNA bind complementary DNA sequence specifically, though with much reduced affinity in comparison with nonmodified PNA. The dioxime-PNA conjugates bind Cu2+ and Ni2+ at microM concentration.