Synthesis and Biological Evaluation of S-, O- and Se-Containing Dispirooxindoles.

A series of novel S-, O- and Se-containing dispirooxindole derivatives has been synthesized using 1,3-dipolar cycloaddition reaction of azomethine ylide generated from isatines and sarcosine at the double C=C bond of 5-indolidene-2-chalcogen-imidazolones (chalcogen was oxygen, sulfur or selenium). The cytotoxicity of these dispiro derivatives was evaluated in vitro using different tumor cell lines. Several molecules have demonstrated a considerable cytotoxicity against the panel and showed good selectivity towards colorectal carcinoma HCT116 p53+/+ over HCT116 p53-/- cells. In particular, good results have been obtained for LNCaP prostate cell line. The performed in silico study has revealed MDM2/p53 interaction as one of the possible targets for the synthesized molecules. However, in contrast to selectivity revealed during the cell-based evaluation and the results obtained in computational study, no significant p53 activation using a reporter construction in p53wt A549 cell line was observed in a relevant concentration range.

Dispirooxindoles Based on 2-Selenoxo-Imidazolidin-4-Ones: Synthesis, Cytotoxicity and ROS Generation Ability.

A regio- and diastereoselective synthesis of two types of dispiro derivatives of 2-selenoxoimidazolidin-4-ones, differing in the position of the nitrogen atom in the central pyrrolidine ring of the spiro-fused system-namely, 2-selenoxodispiro[imidazolidine-4,3'-pyrrolidine-2',3″-indoline]-2″,5-diones (5a-h) and 2-senenoxodispiro[imidazolidine-4,3'-pyrrolidine-4',3″-indoline]-2″,5-diones (6a-m)-were developed based on a 1,3-dipolar cycloaddition of azomethine ylides generated from isatin and sarcosine or formaldehyde and sarcosine to 5-arylidene or 5-indolidene-2-selenoxo-tetrahydro-4H-imidazole-4-ones. Selenium-containing dispiro indolinones generally exhibit cytotoxic activity near to the activity of the corresponding oxygen and sulfur-containing derivatives. Compounds 5b, 5c, and 5e demonstrated considerable in vitro cytotoxicity in the 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) test (concentration of compounds that caused 50% death of cells (CC50) 7.6-8.7 µM) against the A549 cancer cell line with the VA13/A549 selectivity index 5.2-6.9; some compounds (5 and 6) increased the level of intracellular reactive oxygen species (ROS) in the experiment on A549 and PC3 cells using platinized carbon nanoelectrode. The tests for p53 activation for compounds 5 and 6 on the transcriptional reporter suggest that the investigated compounds can only have an indirect p53-dependent mechanism of action. For the compounds 5b, 6b, and 6l, the ROS generation may be one of the significant mechanisms of their cytotoxic action.

CoII Complexes with a Tripyridine Ligand, Containing a 2,6-Di-tert-butylphenolic Fragment: Synthesis, Structure, and Formation of Stable Radicals.

Interaction of a tripyridine ligand bearing a 2,6-di-tert-butylphenolic fragment (L, 2,6-di-tert-butyl-4-(3,5-bis(4-pyridyl)pyridyl)phenol) with CoII pivalate or chloride led to the formation of one-dimensional coordination polymers [Co(L)Cl2] n ·nEtOH (1) and [Co3(L)2(OH)(Piv)5] n (2) or a trinuclear complex Co3(H2O)4(L)2Cl6 (3) (Piv- = pivalate). Chemical oxidation of L and 1-3 by PbO2 or K3[Fe(CN)6], as well as exposure of L (in solution or solid state) and 2 (in solid state) to UV irradiation, led to the formation of free radicals with g = 2.0024, which probably originated because of oxidation of 2,6-di-tert-butylphenolic groups. These radicals were stable for several days in solutions and more than 1 month in solid samples. Irradiation and oxidation of the solid samples probably caused formation of the phenoxyl radical only on their surface. It was shown by density functional theory calculations that exchange coupling between the unpaired electron of the phenoxyl radical and CoII ions was negligibly weak and could not affect the electron paramagnetic resonance signal of the radical, as well as exchange coupling of CoII ions could not be transmitted by L. The latter conclusion was confirmed by the analysis of magnetic properties of 1: temperature dependency of magnetic susceptibility (χM) of 1 could be simulated by a simple model for isolated CoII ions.

Yb3+ can be much better than Dy3+: SMM properties and controllable self-assembly of novel lanthanide 3,5-dinitrobenzoate-acetylacetonate complexes.

The first representatives of the binuclear lanthanide 3,5-dinitrobenzoate-acetylacetonate complexes, namely isostructural compounds [Ln(dnbz)(acac)2(H2O)(EtOH)]2 (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), and Yb (8); dnbz - 3,5-dinitrobenzoate anion; acac - acetylacetonate (pentane-2,4-dionate) anion) were prepared and characterized. The SMM behavior of the Yb compound 8 was shown to be surprisingly less sensitive to the composition of the Yb3+ coordination environment in comparison with that of the Dy derivative. For Yb compound 8, the anisotropy barrier is Δeff/kB = 26 K under the dc field of 2000 Oe. This value is the highest one currently known for binuclear Yb complexes.

Novel mononuclear Ln complexes with pyrazine-2-carboxylate and acetylacetonate co-ligands: remarkable single molecule magnet behavior of a Yb derivative.

A series of novel isomorphic mononuclear complexes [Ln(PyrCOO)(acac)2(H2O)2] (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), Yb (8), Y(9); acac- - acetylacetonate (pentane-2,4-dionate) anion, PyrCOOH is pyrazine-2-carboxylic acid) were prepared. Slow magnetic relaxation indicating SMM behavior was found in complexes 3, 4, 6 and 8. For 4 (Dy), the anisotropy barrier is Δeff/kB = 77 K under a dc field of 1500 Oe. For 8 (Yb), the anisotropy barrier is Δeff/kB = 54 K under a dc field of 2000 Oe which is the highest presently known value for molecular Yb carboxylate complexes and for Yb molecular complexes in general.

Novel mononuclear and 1D-polymeric derivatives of lanthanides and (η6-benzoic acid)tricarbonylchromium: synthesis, structure and magnetism.

Two series of novel heteroleptic derivatives of lanthanides and (η6-benzoic acid)tricarbonylchromium (benchrotrenecarboxylic acid) were synthesized and characterized: mononuclear complexes [Ln(BcrCOO)(acac)2(H2O)2] (Ln = Eu (1), Gd (2), Tb (3a), Dy (4a), Ho (5a)) and 1D-polymeric ones [Ln(BcrCOO)(acac)2(H2O)]n (Ln = Tb (3b), Dy (4b), Ho (5b), Er (6), Tm (7), Yb (8) and Y (9)), Bcr = (η6-C6H5)Cr(CO)3. The molecular and crystal structures of the obtained compounds were determined. Complexes 3a, 4a, 4b, 6 and 8 were found to exhibit SMM properties. Two maxima were observed on χ''(ν) dependencies (LF and HF) for 4a, 4b and 6. For 4a, the anisotropy barriers are Δeff/kB = 100 K and 118 K in zero dc-field (128 K and 143 K in 2000 Oe field) for the LF (low frequency) and HF (high frequency) signals, respectively. These values are the highest ones for Ln carboxylate complexes. The nature of the appearance of two maxima in the system is discussed.

Synthesis, structure, and physical properties of new rare earth ferrocenoylacetonates.

New ferrocenoylacetonate complexes of several rare earth elements, [Ln(fca)3(bpy)]·MeC6H5 (Ln = Pr (), Eu (), Gd (), Tb (), Dy (), Ho (), Y (); bpy - 2,2'-bipyridine; Hfca - FcCOCH2COMe) as well as scandium ferrocenoylacetonate [Sc(fca)3]·0.5MeC6H5 (), were synthesized and characterized by single crystal X-ray diffraction analysis. In the crystal lattice of the isostructural complexes , two [Ln(fca)3(bpy)] molecules form a pair due to stacking interactions between the bpy ligands. The Ln(3+) ions are coordinated in a square antiprism geometry with a coordination number of 8. The Sc(3+) ions in complex are coordinated in an octahedral geometry. Thermolysis of complexes was studied under air and argon atmospheres; in the first case, it affords perovskites LnFeO3 as one of the products. Complexes display single-molecule magnet properties, and the effective relaxation barrier for the Dy complex , was found to be Δeff/kB = 241 K, which is one of the highest values obtained for a mononuclear ß-diketonate lanthanide complex.

Heterometallic Coordination Polymers Assembled from Trigonal Trinuclear Fe2Ni-Pivalate Blocks and Polypyridine Spacers: Topological Diversity, Sorption, and Catalytic Properties.

Linkage of the trigonal complex [Fe2NiO(Piv)6] (where Piv(-) = pivalate) by a series of polypyridine ligands, namely, tris(4-pyridyl)triazine (L(2)), 2,6-bis(3-pyridyl)-4-(4-pyridyl)pyridine (L(3)), N-(bis-2,2-(4-pyridyloxymethyl)-3-(4-pyridyloxy)propyl))pyridone-4 (L(4)), and 4-(N,N-diethylamino)phenyl-bis-2,6-(4-pyridyl)pyridine (L(5)) resulted in the formation of novel coordination polymers [Fe2NiO(Piv)6(L(2))]n (2), [Fe2NiO(Piv)6(L(3))]n (3), [Fe2NiO(Piv)6(L(4))]n·nHPiv (4), and [{Fe2NiO(Piv)6}4{L(5)}6]n·3nDEF (5, where DEF is N,N-diethylformamide), which were crystallographically characterized. The topological analysis of 3, 4, and 5 disclosed the 3,3,4,4-connected 2D (3, 4) or 3,4,4-connected 1D (5) underlying networks which, upon further simplification, gave rise to the uninodal 3-connected nets with the respective fes (3, 4) or SP 1-periodic net (4,4)(0,2) (5) topologies, driven by the cluster [Fe2Ni(µ3-O)(µ-Piv)6] nodes and the polypyridine µ3-L(3,4) or µ2-L(5) blocks. The obtained topologies were compared with those identified in other closely related derivatives [Fe2NiO(Piv)6(L(1))]n (1) and {Fe2NiO(Piv)6}8{L(6)}12 (6), where L(1) and L(6) are tris(4-pyridyl)pyridine and 4-(N,N-dimethylamino)phenyl-bis-2,6-(4-pyridyl)pyridine, respectively. It was shown that a key structure-driven role in defining the dimensionality and topology of the resulting coordination network is played by the type of polypyridine spacer. Compounds 2 and 3 possess a porous structure, as confirmed by the N2 and H2 sorption data at 78 K. Methanol and ethanol sorption by 2 was also studied indicating that the pores filled by these substrates did not induce any structural rearrangement of this sorbent. Additionally, porous coordination polymer 2 was also applied as a heterogeneous catalyst for the condensation of salicylaldehyde or 9-anthracenecarbaldehyde with malononitrile. The best activity of 2 was observed in the case of salicylaldehyde substrate, resulting in up to 88% conversion into 2-imino-2H-chromen-3-carbonitrile.

Modeling of catalytically active metal complex species and intermediates in reactions of organic halides electroreduction.

The results of quantum chemical modeling of organic and metal-containing intermediates that occur in electrocatalytic dehalogenation reactions of organic chlorides are presented. Modeling of processes that take place in successive steps of the electrochemical reduction of representative C1 and C2 chlorides - CHCl3 and Freon R113 (1,1,2-trifluoro-1,2,2-trichloroethane) - was carried out by density functional theory (DFT) and second-order Møller-Plesset perturbation theory (MP2). It was found that taking solvation into account using an implicit solvent model (conductor-like screening model, COSMO) or considering explicit solvent molecules gave similar results. In addition to modeling of simple non-catalytic dehalogenation, processes with a number of complexes and their reduced forms, some of which were catalytically active, were investigated by DFT. Complexes M(L1)2 (M = Fe, Co, Ni, Cu, Zn, L1H = Schiff base from 2-pyridinecarbaldehyde and the hydrazide of 4-pyridinecarboxylic acid), Ni(L2) (H2L2 is the Schiff base from salicylaldehyde and 1,2-ethylenediamine, known as salen) and Co(L3)2Cl2, representing a fragment of a redox-active coordination polymer [Co(L3)Cl2]n (L3 is the dithioamide of 1,3-benzenedicarboxylic acid), were considered. Gradual changes in electronic structure in a series of compounds M(L1)2 were observed, and correlations between [M(L1)2](0) spin-up and spin-down LUMO energies and the relative energies of the corresponding high-spin and low-spin reduced forms, as well as the shape of the orbitals, were proposed. These results can be helpful for determination of the nature of redox-processes in similar systems by DFT. No specific covalent interactions between [M(L1)2](-) and the R113 molecule (M = Fe, Co, Ni, Zn) were found, which indicates that M(L1)2 electrocatalysts act rather like electron transfer mediators via outer-shell electron transfer. A relaxed surface scan of the adducts {M(L1)2·R113}(-) (M = Ni or Co) versus the distance between the chlorine atom leaving during reduction and the corresponding carbon atom showed an energy barrier to electron transfer (the first stage of R113 catalytic reduction), while DFT optimization of the {Ni(L2)·R113}(-) adduct showed barrier-free decomposition. The difference between the stabilities of the {Ni(L1)2·R113}(-) and {Ni(L2)·R113}(-) adducts correlates with the difference between the catalytic activities of Ni(L1)2 and Ni(L2) in the electrochemical reduction of R113.

Heterodinuclear (Sm, Tb) lanthanide pivalates with heterocyclic N-donors: synthesis, structure, thermal behavior, and magnetic and photoluminescence properties.

Heterobimetallic complexes [SmTb(piv)6(phen)2] (1), [SmTb(piv)6(bath)2]·1.75EtOH (2a·1.75EtOH), [SmTb(piv)6(bath)2]·2EtOH (2b·2EtOH), and [SmTb(piv)6(bath)2]·EtOH (2b·EtOH), where piv is (CH3)3CCO2(-), phen is 1,10-phenanthroline, and bath is 4,7-diphenyl-1,10-phenanthroline, were synthesized and studied by X-ray diffraction. It was shown that complexes 2a·1.75EtOH and 2b·2EtOH have different molecular and crystal structures. Complexes 2a·1.75EtOH, 2b·2EtOH, and 2b·EtOH differ in the structural functions of µ2-piv anions. 2a·1.75EtOH contains two µ2-piv-κ(2)O,O' anions and two µ2-piv-κ(2)O,O,O' anions, whereas 2b·2EtOH and 2b·EtOH have four µ2-piv-κ(2)O,O' anions. According to the mass spectrometry data, the dimeric molecule [SmTb(piv)6] is the major metal-containing component of gas-phase complexes 1, 2a·1.75EtOH, and 2b·2EtOH. The characteristic features of the thermal behavior of these complexes were revealed, and their magnetic and photoluminescence (PL) properties were investigated. A unique feature of desolvated complexes 2a·1.75EtOH and 2b·2EtOH is melting at high temperatures before thermal decomposition. The magnetic properties of 1 and 2a·1.75EtOH are determined mainly by the Tb(3+) ions. The optical properties of these complexes and their homodinuclear analogs were analyzed by photoluminescence, excitation, phosphorescence, and scattering spectroscopy and by lifetime measurements at 77 K and 300 K. As the temperature decreases to 77 K, the PL intensity of Tb(3+) ions in 1 and 2a·1.75EtOH substantially increases by 40 and 100 times, respectively, compared to 300 K. The PL color evidently changes from red at 300 K to bright green at 77 K. Based on these results, the mechanism of intramolecular energy transfer between the ligand levels and Sm(3+) and Tb(3+) ions under UV radiation was proposed.

Platinum acetate blue: synthesis and characterization.

Platinum acetate blue (PAB) of the empirical formula Pt(OOCMe)2.5±0.25, a byproduct in the synthesis of crystalline platinum(II) acetate Pt4(OOCMe)8, is an X-ray amorphous substance containing platinum in the oxidation state between (II) and (III). Typical PAB samples were studied with X-ray diffraction, differential thermal analysis-thermogravimetric, extended X-ray absorption fine structure, scanning electron microscopy, transmission electron microscopy, magnetochemistry, and combined quantum chemical density functional theory-molecular mechanics modeling to reveal the main structural features of the PAB molecular building blocks. The applicability of PAB to the synthesis of platinum complexes was demonstrated by the preparation of the new homo- and heteronuclear complexes Pt(II)(dipy)(OOCMe)2 (1), Pt(II)(µ-OOCMe)4Co(II)(OH2) (2), and Pt(III)2(OOCMe)4(O3SPhMe)2 (3) with the use of PAB as starting material.

Aqueous stability of alumina and silica perhydrate hydrogels: experiments and computations.

Alumina and silica perhydrate hydrogels were synthesized. Raman spectroscopy and solid (27)Al MAS NMR confirmed alumina perhydrate formation. Thermal and aqueous stability of alumina and silica perhydrates was studied, and they showed exceptionally high stabilities. Alumina perhydrate retained some of the hydrogen peroxide even at 170 °C, higher than any other reported perhydrate, whereas the silica perhydrate lost its hydrogen peroxide content already at 90 °C. The silica perhydrate lost all its peroxide content upon immersion in water, whereas the alumina perhydrate was stable under near-neutral pH conditions. A computational study was conducted in order to glean molecular insight into the observed thermal and aqueous stability of alumina compared to silica perhydrate. Comparison of the hydrogen bond features and the stabilization energies of the hydrate and perhydrate of silica and alumina revealed a higher preference for hydrogen peroxide over water by alumina relative to silica. This is shown to be due to hydrogen peroxide being a better hydrogen donor than water and due to the superior hydrogen accepting propensity of alumina compared to silica.

Temperature-dependent zero-field splitting in a copper(II) dimer studied by EPR.

We report on the synthesis and temperature-dependent magnetic properties observed in an exchange-coupled copper(II) dimer using X/Q-band Electron Paramagnetic Resonance (EPR) spectroscopy (9/34 GHz). It has been found that the zero-field splitting (D) in the dimer changes gradually by a factor close to two in the temperature range from T = 50 to 300 K. X-ray diffraction data show that this dimer consists of two five-coordinated copper ions, one of which has a highly asymmetric geometry intermediate between square pyramid and trigonal bipyramid. The copper-copper distance in the dimer is temperature-independent, whereas the degree of trigonality in an asymmetric unit decreases as the temperature is lowered. Therefore we suppose that the observed dependence D(T) originates from the interplay of different exchange interaction pathways driven by these thermal changes. Magnetic susceptibility measurements reveal weak ferromagnetic interactions, whose anisotropic parts should indeed be very sensitive to the subtle changes in the geometry and may result in apparent D(T). Apart from being a very unusual example of magneto-structural correlations, this and similar dimeric systems can be considered as an interesting type of new materials exhibiting strongly temperature-dependent magnetic properties.

2D porous honeycomb polymers versus discrete nanocubes from trigonal trinuclear complexes and ligands with variable topology.

Trinuclear building block {Fe(2)NiO(Piv)(6)} (Piv = pivalate), which possessed pseudo-D(3h) symmetry, was linked by two ligands, pseudo-D(3h) ligand tris-(4-pyridyl)pyridine (L1) and C(2v) ligand 4-(N,N-dimethylamino)phenyl-2,6-bis(4-pyridyl)pyridine (L2) into two products with different topologies: 2D coordination polymer [Fe(2)NiO(Piv)(6)(L1)](n) (1), and discrete molecule [{Fe(2)NiO(Piv)(6)}(8) {L2}(12)], which had a nanocube structure (2). In compound 1, trinuclear {Fe(2)NiO(Piv)(6)} blocks were linked through ligand L1 into layers with honeycomb topology. In compound 2, eight trinuclear blocks were located in the vertices of the nanocube, with each L2 ligand linked to two {Fe(2)NiO(Piv)(6)} units. In the crystal structure, these nanocubes formed infinite catenated chains. Analysis of possible structures that could be assembled from these building blocks showed that compounds 1 and 2 corresponded to their respective predicted topologies. Compound [1⋅solvent] possessed a porous structure, in which the voids were filled by solvent molecules (DMF or DMSO). This structure was retained following desolvation, and compound 1 absorbed significant quantities of N(2) and H(2) at 78 K (S(BET) = 730 m(2) g(-1), H(2) sorption capacity: 0.9 % by weight at 865 Torr). Desolvation of [2⋅solvent] led to disorder of its crystal structure, and compound 2 only adsorbed negligible quantities of N(2) but adsorbed 0.27 % H(2) (by weight) at 855 Torr and 78 K. The magnetic properties of these complexes (temperature dependence of molar magnetic susceptibility) were governed by the magnetic properties of the trinuclear "building block".