Search

Coordination of a stereochemically defined P3‐chain to a series of transition metal carbonyls [M(CO)x]z− (M = Mn (x = 5, z = 1), Fe (x = 4, z = 2) or Co (x = 4, z = 1)) is explored using a [3]ferrocenophane scaffold. A gradual transition from η1‐, η2‐ to η3‐coordination is observed where in the η2‐mode the terminal positions of the phosphorus chain are bridged. With an excess of cobalt carbonyl successive P–P bond activation and gradual separation of the central phosphorus atoms from the phosphorus chain has been observed. This process is reversible and with suitable reagents such as methyl lithium, the P3‐unit is regenerated in stereospecific manner. The bonding situation and steps of the gradual P–P bond activation are investigated by DFT calculations as well as experimental methods (e.g., NMR spectroscopy, X‐ray crystallography). [ABSTRACT FROM AUTHOR]

Substituted acrylamides have found an extensive application in organic and medical chemistry; therefore, it is very important to get insight into their features such as electronic structure, spectral properties, and stereochemical transformations. A correct interpretation of the chemical behavior and biological activity of these heteroatomic systems is impossible without knowledge of the structure of stereodynamic forms and factors determining their relative stability. The structure and peculiarities of stereodynamic behavior of substituted acrylamides and their model compounds were studied by dynamic and multinuclear 1H, 13C, and 15N nuclear magnetic resonance (NMR) spectroscopy in CDCl3 and DMSO‐d6 solution. It has been established that acrylamides in solution are realized as Z‐ and E‐isomers, with the E‐rotamer being somewhat predominant. The obtained experimental values of the free activation energy of rotamers vary within 15–17 kcal/mol, depending on the stereochemical structure of the molecule. 15N NMR spectroscopy is the most reliable and fastest method for determining the structural and stereochemical features of nitrogen‐containing compounds. [ABSTRACT FROM AUTHOR]

The Li 1+x Al x Ti 2−x (PO 4) 3 (LATPx) series displays the highest "bulk" reported conductivity, but a much lower "overall" contribution, that changes with the powder preparation and sintering conditions. In this work, the preparation of LATPx ceramics is discussed, by using the sol-gel technique for powders synthesis and mild spark plasma (SPS) for ceramics sintering at 800 °C. An "overall" conductivity ~ 2.10−3 Ω−1 cm−1 was obtained for the x = 0.4 composition, that was the result of a high "bulk" conductivity, an optimized microstructure and almost full density, in absence of micro-cracks, with a small content of secondary phases and clean grain boundaries. Fast-ion ceramics prepared by SPS are good candidates for solid electrolytes in all solid state batteries (ASSB). [ABSTRACT FROM AUTHOR]

Mixed amine/ammine motifs are important features in newer generation platinum anticancer agents, including the Pt(IV) prodrug satraplatin. One synthetic route that can be used to access platinum molecules with such structures exploits the trans effect during NH3-mediated cleavage of iodo-bridged platinum(II) dimers of the form [Pt(Am)I(μ-I)]2, where Am is an amine. A clear picture of the nature of these dimers that is consistent with the reactivity they exhibit has remained elusive. Moreover, technical aspects of this chemistry have impeded its more widespread use. We present here an improved strategy that permits isolation and use of [Pt(Am)I(μ-I)]2, where Am is cyclohexylamine, within minutes as opposed to weeks, as previously reported. A detailed spectroscopic, crystallographic, and chromatographic investigation of this intermediate in the synthesis of satraplatin is also presented with a discussion of the ability of both cis and trans isomers of the dimer to produce exclusively cis-[Pt(NH2C6H11)(NH3)I2] upon treatment with NH3.

The siderophore organic ligand N,2-dihydroxybenzamide (H2dihybe) incorporates the hydroxamate group, in addition to the phenoxy group in the ortho-position and reveals a very rich coordination chemistry with potential applications in medicine, materials, and physical sciences. The reaction of H2dihybe with TiCl4 in methyl alcohol and KOH yielded the tetranuclear titanium oxo-cluster (TOC) [TiIV4(μ-O)2(HOCH3)4(μ-Hdihybe)4(Hdihybe)4]Cl4∙10H2O∙12CH3OH (1). The titanium compound was characterized by single-crystal X-ray structure analysis, ESI-MS, 13C, and 1H NMR spectroscopy, solid-state and solution UV–Vis, IR vibrational, and luminescence spectroscopies and molecular orbital calculations. The inorganic core Ti4(μ-O)2 of 1 constitutes a rare structural motif for discrete TiIV4 oxo-clusters. High-resolution ESI-MS studies of 1 in methyl alcohol revealed the presence of isotopic distribution patterns which can be attributed to the tetranuclear clusters containing the inorganic core {Ti4(μ-O)2}. Solid-state IR spectroscopy of 1 showed the presence of an intense band at ~800 cm−1 which is absent in the spectrum of the H2dihybe and was attributed to the high-energy ν(Ti2–μ-O) stretching mode. The ν(C=O) in 1 is red-shifted by ~10 cm−1, while the ν(N-O) is blue-shifted by ~20 cm−1 in comparison to H2dihybe. Density Functional Theory (DFT) calculations reveal that in the experimental and theoretically predicted IR absorbance spectra of the ligand and Ti-complex, the main bands observed in the experimental spectra are also present in the calculated spectra supporting the proposed structural model. 1H and 13C NMR solution (CD3OD) studies of 1 reveal that it retains its integrity in CD3OD. The observed NMR changes upon addition of base to a CD3OD solution of 1, are due to an acid–base equilibrium and not a change in the TiIV coordination environment while the decrease in the complex’s lability is due to the improved electron-donating properties which arise from the ligand deprotonation. Luminescence spectroscopic studies of 1 in solution reveal a dual narrow luminescence at different excitation wavelengths. The TOC 1 exhibits a band-gap of 1.98 eV which renders it a promising candidate for photocatalytic investigations.

tert-Butyl-substituted diphospha[2]ferrocenophane was used as a stereochemically confined diphosphane to investigate the addition of various dichalcoganes (R2Ch2; Ch = S, Se, Te and R = Me, Ph). Bischalcogenophosphinous acid esters bearing four soft donor sides were obtained as a mixture of rac and meso diastereomers and characterized by means of multinuclear NMR and X-ray analysis. The coordination chemistry of multidentate ligand 3b was explored toward d10 coinage metal centers (Cu(I), Ag(I), and Au(I)), yielding various bimetallic complexes.

A series of new (E)-3(5)-[β-(aryl)-ethenyl]-5(3)-phenyl-1H-pyrazoles bearing fluorine atoms at different positions of the aryl group have been synthesized starting from the corresponding β-diketones. All compounds have been characterized by elemental analysis, DSC as well as NMR (1H, 13C, 19F and 15N) spectroscopy in solution and in solid state. Three structures have been solved by X-ray diffraction analysis, confirming the tautomeric forms detected by solid state NMR. The in vitro study of their inhibitory potency and selectivity on the activity of nNOS and eNOS (calcium-calmodulin dependent) as well as iNOS (calcium-calmodulin independent) isoenzymes is presented. A qualitative structure–activity analysis allowed the establishment of a correlation between the presence/ absence of different substituents with the inhibition data proving that fluorine groups enhance the biological activity. (E)-3(5)-[β-(3-Fluoro-4-hydroxyphenyl)-ethenyl]-5(3)-phenyl-1H-pyrazole (13), is the best inhibitor of iNOS, being also more selective towards the other two isoforms.

Treatment of a chelating silane 1-(dimethylsilyl)-2-silylbenzene (4) with Pd(PEt3)4 in the ratio of 2:1 selectively afforded a unique mononuclear palladium complex [{1,2-C6H4(SiMe2)(SiH)}2Pd(PEt3)2] (6), which was formed by two Si-Si coupling reactions between the SiH2 groups and the SiMe2 moieties from two hydrosilane ligands. Complex 6 was structurally characterized by single crystal X-ray analysis and multinuclear NMR spectroscopic studies and is one of the very few examples of cis-bis(silyl)palladium(II) complexes containing in situ formed Si-Si single bonds. [ABSTRACT FROM AUTHOR]

Encapsulation of platinum-based antitumor drugs into host molecules is a rapidly growing field, as it provides the potential to reduce the toxicity and overcome tumor resistance issues, with cucurbit[ n ]uril family being a very promising class of potential hosts. Although, previously it was reported that carboplatin, a second generation platinum-based antitumor drug, did not interact with cucurbit[7]uril, in this work, we have observed such an interaction by means of multinuclear NMR spectroscopy. Apparently, upon the interaction with cucurbit[7]uril in aqueous solution, carboplatin decomposes into 1,1-cyclobutane dicarboxylic acid and some cis -PtL 2 (NH 3 ) 2 (L = H 2 O or OH − ) which forms a relatively stable inclusion complex with cucurbit[7]uril. DFT calculations of the geometry of hypothetical complexes and NMR shielding of 1 H, 13 C, and 195 Pt nuclei help with interpretation of the experimental NMR results. [ABSTRACT FROM AUTHOR]

The catalytic process of cyclohexanone oxidation by hydrogen peroxide was investigated using in situ NMR spectroscopy in real working conditions. The behavior of the Keggin heteropolyacid H 3 PMo 12 O 40 , used as a model catalyst, was explored before and after adding the oxidant agent. This study revealed the evolution pathways to different reduced states of H 3 PMo 12 O 40 and its reversible transformation into peroxomolybdate complexes. These latter were identified as the active species for the adipic acid formation, while the acid function of the catalyst was found important for the substrate activation via ketonic-enolic tautomerism. The oxidative mechanism of the cyclohexanone was described through three successive steps to produce adipic acid. [ABSTRACT FROM AUTHOR]

Three mononuclear organotin(IV) complexes supported by Schiff bases have been synthesized. The complexes [(C6H5)2Sn(L)] (1), [(t‐Bu)2Sn(L)] (2) and [(t‐Bu)2Sn(L')] (3) (L, L' = deprotonated Schiff bases) were obtained in good yield by the reaction of Schiff bases H2L or H2L′ with corresponding diorganotin dichlorides respectively. All newly synthesized complexes were characterized by means of FT‐IR spectroscopy, elemental analysis and multinuclear (1H, 13C and 119Sn) NMR spectroscopy. In addition, single crystal X‐ray diffraction analyses were employed to establish the solid state molecular structures of these complexes. The structures of 1–3 reveal that all complexes are mononuclear with a five‐coordinated tin(IV) centre in it. The absorption and emission properties of all complexes have been investigated. Moreover, cytotoxicity and fluorescence cell imaging studies of theses complexes have been performed. [ABSTRACT FROM AUTHOR]

The platinum(II) oxalato complexes [Pt(ox)(naza)2] (1–3) were synthesized and characterized by elemental analysis (C, H, N), multinuclear NMR spectroscopy (1H, 13C, 15N, 195Pt) and electrospray ionization mass spectrometry (ESI-MS); naza = 4-chloro-7-azaindole (4Claza; 1), 3-bromo-7-azaindole (3Braza; 2) or 4-bromo-7-azaindole (4Braza; 3). The prepared substances were screened for their in vitro antitumor activity on the osteosarcoma (HOS) and breast adenocarcinoma (MCF7) human cancer cell lines, where 2 showed moderate antitumor effect (IC50 = 27.5 μM, and 18.3 μM, respectively). The complex 2 was further tested on a panel of six others human cancer cell lines, including the malignant melanoma (G361), cervix carcinoma (HeLa), ovarian carcinoma (A2780), cisplatin-resistant ovarian carcinoma (A2780R), lung carcinoma (A549) and prostate adenocarcinoma (LNCaP). This substance was found to be moderate antitumor effective against G361 (IC50 = 17.3 μM), HeLa (IC50 = 31.8 μM) and A2780 (IC50 = 19.2 μM) cell lines. The complex 2 was also studied by NMR for its solution stability and by ESI-MS experiments for its ability to interact with biomolecules, such as cysteine, glutathione or guanosine 5'-monophosphate.

A one-step synthetic procedure using the reaction of potassium bis(oxalato)platinate(II) with the corresponding N6-benzyladenosine derivative (nL) provided the [Pt(ox)(nL)2]∙1.5H2O oxalato (ox) complexes 1–5, involving the nL molecules as monodentate coordinated N-donor ligands. The complexes were thoroughly characterized by elemental analysis, multinuclear (1H, 13C, 15N, 195Pt) and two dimensional NMR, infrared and Raman spectroscopy, and mass spectrometry, proving their composition and purity as well as coordination of nL through the N7 atom of the purine moiety. Geometry of [Pt(ox)(4FL)2] (5) was optimized at the B3LYP/LANLTZ/6-311G** level of theory. The complexes were screened for their in vitro cytotoxicity against two human cancer cell lines (HOS osteosarcoma and MCF7 breast adenocarcinoma), but they did not show any effect up to the concentration of 50.0 µM (compounds 1, 2) or 20.0 µM (compounds 3–5).

The interaction of MeSn(IV) and MeSn(IV) with a prodrug, sodium 2-mercaptoethane sulfonate (HSCHCHSONa, MESNA) abbreviated as (HL), has been studied potentiometrically in aqueous solution ( I = 0.1 mol·L KNO, 298 K). The concentration distribution of various species formed in the solution was studied with changes in pH (~3-11). A strong coordination of MESNA with metal through the S atom of thiol group has been found. In the MeSn(IV)-HL system, the species [MeSn(L)] (53.1-75.6%) is predominant at acidic pH (3.73 ± 0.02) and the species [MeSn(L)OH] (29.4-38.5%) is predominant at basic pH (10.32 ± 0.08). In contrast, for the MeSn(IV) system, [MeSnL] (37.0-57.4%) is the major species at pH 7.65 ± 0.03 and [MeSn(OH)] (49.9-67.2%) and [MeSn(L)(OH)] (30.2-46.5%) are the major species at pH 11.05 ± 0.01. However, at physiological pH (7.01 ± 0.32), in both (1:1) and (1:2) MeSn(IV)-HL systems, the species [MeSn(L)(OH)] (67.2-89.9%) is predominant, whereas for MeSn(IV)-HL (1:1) and (1:2) systems, [MeSn(OH)] (53.5%) and [MeSnL] (56.8%) are the respective predominant species. In order to characterize the possible geometry of the proposed complex species, multinuclear (H, C and Sn) NMR studies were carried out at different pHs. No polymeric species were detected in the experimental pH range. [ABSTRACT FROM AUTHOR]

Treatment of 1,2-C6H4(SiH3)(SiH3) (1) or 1,2-C6H4(SiMe2H)(SiH3) (2) with Pd(dcpe)(PEt3)2 (dcpe=Cy2PCH2CH2PCy2) in the ratio of 1:1 affords two cis-bis(silyl) palladium(II) complexes {1,2-C6H4(SiH2)(SiH2)}PdII(dcpe) (3) and {1,2-C6H4(SiMe2)(SiH2)}PdII(dcpe) (4) with good thermal stability respectively. To the best of our knowledge, only ten silyl palladium complexes prepared from these two chelating hydrosilane ligands are presented in the Cambridge Structural Database. The structures of complexes 3 and 4 are unambiguously determined by single crystal X-ray analysis and multinuclear NMR spectroscopic studies. [ABSTRACT FROM AUTHOR]

The preparation and crystal structures of four β-ketoimines with bulky aryl nitrogen substituents (2,6-diisopropylphenyl and 2,4,6-trimethylphenyl) and varying degrees of backbone methyl substitution are reported. Backbone substitution "pinches" the chelate ring. Deprotonation with n-butyllithium leads to dimeric Li2O2 clusters, as primary laddered units, with an open transoid geometry as shown by crystal structures of three examples. The coordination sphere of each lithium is completed by one tetrahydrofuran ligand. NMR spectra undertaken in either C6D6 or 1:1 C6D6/d8-THF show free THF in solution and the chemical shifts of ligand methyl groups experience significant ring-shielding which can only occur from aryl rings on adjacent ligands. Both features point to conversion to higher-order aggregates when the THF concentration is reduced. Recrystallization of the materials from hydrocarbon solutions results in secondary laddering as tetrameric Li4O4 clusters with a cuboidal core, three examples of which have been crystallographically characterised. These clusters are relatively insoluble and melt up to 250 °C; a consideration of the solid-state structures indicates that the clusters with 2,6-diisopropylphenyl substituents form very uniform ball-like molecular structures that will only be weakly solvated. [ABSTRACT FROM AUTHOR]

Two novel tetrafluorinated 1,5-benzodiazepinones were synthesized and their X-ray structures determined. 6,7,8,9-Tetrafluoro-4-methyl-1,3-dihydro-2H-1,5-benzodiazepin-2-one crystallizes in the monoclinic P21/c space group and 6,7,8,9-tetrafluoro-1,4-dimethyl-1,3-dihydro-2H-1,5-benzodiazepin-2-one in the triclinic P−1 space group. Density functional theory studies at the B3LYP/6-311++G(d,p) level were carried out on these compounds and on four non-fluorinated derivatives, allowing to calculate geometries, tautomeric energies and ring-inversion barriers, that were compared with the experimental results obtained by static and dynamic NMR in solution and in solid state.

The platinum(II) complexes trans-[PtCl2(Ln)2]∙xSolv 1–13 (Solv = H2O or CH3OH), involving N6-benzyladenosine-based N-donor ligands, were synthesized; Ln stands for N6-(2-methoxybenzyl)adenosine (L1, involved in complex 1), N6-(4-methoxy-benzyl)adenosine (L2, 2), N6-(2-chlorobenzyl)adenosine (L3, 3), N6-(4-chlorobenzyl)-adenosine (L4, 4), N6-(2-hydroxybenzyl)adenosine (L5, 5), N6-(3-hydroxybenzyl)-adenosine (L6, 6), N6-(2-hydroxy-3-methoxybenzyl)adenosine (L7, 7), N6-(4-fluoro-benzyl)adenosine (L8, 8), N6-(4-methylbenzyl)adenosine (L9, 9), 2-chloro-N6-(3-hydroxy-benzyl)adenosine (L10, 10), 2-chloro-N6-(4-hydroxybenzyl)adenosine (L11, 11), 2-chloro-N6-(2-hydroxy-3-methoxybenzyl)adenosine (L12, 12) and 2-chloro-N6-(2-hydroxy-5-methylbenzyl)adenosine (L13, 13). The compounds were characterized by elemental analysis, mass spectrometry, IR and multinuclear (1H-, 13C-, 195Pt- and 15N-) and two-dimensional NMR spectroscopy, which proved the N7-coordination mode of the appropriate N6-benzyladenosine derivative and trans-geometry of the title complexes. The complexes 1–13 were found to be non-toxic in vitro against two selected human cancer cell lines (HOS and MCF7; with IC50 > 50.0 µM). However, they were found (by ESI-MS study) to be able to interact with the physiological levels of the sulfur-containing biogenic biomolecule L-methionine by a relatively simple 1:1 exchange mechanism (one Ln molecule was replaced by one L-methionine molecule), thus forming a mixed-nitrogen/sulfur-ligand dichlorido-platinum(II) coordination species.

A series of mono-, di- and triorganotin compounds with general formulae [RSnL2Cl], R = Bu (compound 3), [R2SnL2], where R = Me, Et, Bu, Oct (compounds 1, 2, 4 and 6) and [R3SnL], where R = Bu, Cy and Ph (compounds 5, 7 and 8) and where L = 3,4-methylenedioxy-6-nitrophenylpropenoic acid have been prepared and characterized by elemental analysis, multinuclear (1H-, 13C- and 119Sn-) NMR and mass spectrometry. The ligand and its respective organotin complexes were screened for cytotoxicity using the brine shrimp lethality assay and for antitumor activity using the crown gall tumor inhibition (potato disc) assay. The bioassay results support the conclusion that the biological activities of these synthetic compounds are in the following order: [RSnL2Cl] < [R2SnL2] < [R3SnL].

Regioselective introduction of nitro groups was studied in the case of pyrazoles containing a 1- or 5-tetrazole substituent at position 3(5). All the possible isomeric C-mononitropyrazoles were synthesized. The reduction of these compounds gave the respective 3(5)-amino-5(3)-tetrazolylpyrazoles, which were nitrated to 3(5)-nitramino-4-nitro-5(3)-tetrazolylpyrazoles. The reaction of 1-(nitropyrazol-3(5)-yl)tetrazoles with hydroxylamine- O-sulfonic acid produced the respective N-amino derivatives. [ABSTRACT FROM AUTHOR]

Three structurally different mononuclear dichlorido platinum(II) complexes with 5,7-diethyl-1,2,4-triazolo[1,5- a ]pyrimidine (detp) were synthesized and characterized through multinuclear magnetic resonance ( 1 H, 13 C, 15 N, 195 Pt) and infrared spectroscopy. The X-ray structure of cis -[PtCl 2 (detp)(dmso)] ( 2 ) was determined using the single-crystal X-ray diffraction technique. The molecular structure of ( 2 ) exhibits a square planar geometry surrounding the Pt(II) ion with a unique placement of two chlorido ligands in the cis position in the presence of a S-dmso molecule in the coordination sphere. All NMR data obtained in solution unambiguously confirmed the square planar geometry of Pt(II) with monodentate N3-bonded detp, a monodentate second ligand (detp or NH 3 or dmso) and two chlorido ligands in the cis geometry. Cytotoxicity tests using human carcinoma cell lines, specifically the T47D (breast cancer), A549 (non-small cell lung carcinoma), and LoVo (colon cancer) cell lines, and the healthy cell line BALB/3T3 (mouse embryonic fibroblast), indicated that only cis -[PtCl 2 (detp) 2 ] ( 1 ) possesses similar in vitro cytotoxicity against T47D and sevenfold lower toxicity than cisplatin. [ABSTRACT FROM AUTHOR]

The reaction of 1,2-C 6 H 4 (SiMe 2 H)(SiH 3 ) ( 1 ) with Pt(dmpe)(PEt 3 ) 2 (dmpe = Me 2 PCH 2 CH 2 PMe 2 ) in the ratio of 1:1 yields the complex {1,2-C 6 H 4 (SiMe 2 )(SiH 2 )}Pt II (dmpe) ( 2 ), which has unique reactivity towards sterically unhindered phenol to form an unusual diphenoxy substituted (bis)silyl platinum(II) compound ( 3 ). Only 6 examples of bis(silyl) platinum(II) complexes prepared from this chelating hydrosilane ligand have been registered in the Cambridge Structural Database. The structure of complex ( 3 ) was unambiguously determined by single crystal X-ray analysis and multinuclear NMR spectroscopic studies. [ABSTRACT FROM AUTHOR]

Lithium bis(diisopropylphosphino)amide LiN[P( i -Pr) 2 ] 2 reacts with SnCl 2 or GeCl 2 ·dioxane in the presence of excess n -BuLi to produce the bicyclic compounds {MN[P( i -Pr) 2 ] 2 } 2 (M = Sn, Ge) which feature Sn 2 2+ or Ge 2 2+ units bridged by phosphorus. When paired with B(C 6 F 5 ) 3 in THF, the Lewis-basic M 2 2+ complexes participate in a THF ring-opening reaction. Quite surprisingly, in the absence of THF one para -F atom from B(C 6 F 5 ) 3 is activated and displaced to B while a new M–C bond is formed. Each of these complexes, as well as Cl 2 Sn{N[P( i- Pr) 2 ] 2 } 2 and {ClSnN[P( i- Pr) 2 ] 2 } 2 were characterized by a combination of multi-nuclear NMR spectroscopy and single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Imidazolium (IMILs) with a piperidine moiety appended via variable length methylene spacers (with n = 1-4) were studied computationally to assess their potential to act as internal base for N-heterocyclic carbene (NHC) generation. Proton transfer energies computed by B3LYP/6-311+G(2d,p) were least endothermic for the basic-IL with n = 3, whose optimized structure showed the shortest C2-H----N(piperidine) distance. Inclusion of counter anion (Cl or NTf2) caused dramatic conformational changes to enable close contact between the acidic C2-H and the anions. To examine the prospect for internal C2-H----N coordination, multinuclear NMR data (1H, 15N, and 13C) were computed by gauge independent atomic orbitals-density functional theory (GIAO-DFT) in the gas phase and in several solvents by the PCM method for comparison with the experimental NMR data for the basic ILs (with n = 2-4) synthesized in the laboratory. These studies indicate that interactions with solvent and counter ion are dominant forces that could disrupt internal C2-H----N coordination/proton transfer, making carbene generation from these basic-ILs unlikely without an added external base. Therefore, the piperidine-appended IMILs appear suitable for application as dual solvent/base in organic/organometallic transformations that require the use of mild base, without the necessity to alkylate at C-2 to prevent N-heterocyclic carbene formation. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The 28 membered macrocyclic ligand L ( 1 ) containing S, Se and N donor atoms was obtained by the [2 + 2] condensation reaction between bis( o -formylphenyl)selenide and bis(2-aminoethyl)sulfane. The reaction between 1 and AgX in a 1:1 molar ratio resulted in the ionic species [LAg] + X − [X = OSO 2 CF 3 ( 2 ), PF 6 ( 3 ) and BF 4 ( 4 )]. The NMR spectra of ligand 1 at room temperature suggest a mixture of two invertomers in chlorinated solvents, while the spectra of 1 in C 6 D 6 indicate only one species in solution. The molecular structures of 1 and the silver(I) complexes 2 and 3 ·2CHCl 3 were determined by single-crystal X-ray diffraction. A N,N,S,S,Se,Se coordination behavior of the ligand and a distorted octahedral environment about Ag(I) were observed in the [LAg] + cation in both complexes. [ABSTRACT FROM AUTHOR]

Treatment of 1,2-C 6 H 4 (SiH 3 )(SiH 3 ) ( 1 ) with [Pt(depe)(PEt 3 ) 2 ] (depe = Et 2 PCH 2 CH 2 PEt 2 ) in the ratio of 1:1 yields the complex [Pt II {1,2-C 6 H 4 (SiH 2 )(SiH 2 )}(depe)] ( 2 ), which has unique reactivity towards sterically unhindered alcohol to form an unusual tetra-alkoxy substituted silyl platinum(II) compound ( 3 ). Only 2 examples of bis(silyl)platinum(II) complexes prepared from this chelating hydrosilane ligand have been registered in the Cambridge Structural Database. The structure of complex ( 3 ) was unambiguously determined by multinuclear NMR spectroscopic studies and single crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

Water assisted phase transformation process from crystalized AlPO 4 -5 to AlPO 4 -tridymite was studied by the combination of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and in situ multinuclear MAS NMR. It is found that water first activates the residue amorphous aluminophosphate in crystalized AlPO 4 -5 sample through hydrolysis and condensation reactions. Then the activated aluminophosphate species reassemble into AlPO 4 -tridymite crystalline. Meanwhile, AlPO 4 -5 transforms into orthorhombic phase during heating process. With further crystallization of AlPO 4 -tridymite, the amorphous phase is gradually consumed, and mass transportation between AlPO 4 -5 and AlPO 4 -tridymite is established through gradually amorphization of AlPO 4 -5. Finally, most of the AlPO 4 -5 transforms into the thermodynamically stable dense phase AlPO 4 -tridymite. [ABSTRACT FROM AUTHOR]

The reaction of (SiH3)(SiMeBu t 2) with [Pt(PEt3)4] and dcpe gave [Pt{(SiH2)(SiMeBu t 2)}2(dcpe)] (dcpe=Cy2PCH2CH2PCy2), which has been structurally characterised by single-crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

Reaction of Li(P3C2Bu t2 ) with BrCH(SiMe3)2 results in a novel organophosphorus compound with the formula, P6C4Bu t4 CHSiMe3 (1). Compound 1 was fully characterised spectroscopically and its unique molecular structure determined by single crystal X-ray diffraction. Another isomer (2) with a saturated structure was also fully characterised.

Sodium calcium aluminoborophosphate glasses (some containing Ga 3+ ) simulate interactions at the interface between β-tricalcium phosphate crystal waste hosts (β-TCP and β-TC(Ga)P) and sodium aluminoborophosphate (NABP) glass encapsulant. 31 P NMR and Raman spectroscopies show progression from Na + charge-balanced, mixed Q Al P = Q 2 1 + Q 3 0 in the NABP base glass, to Ca 2+ charge-balanced, Q 0 0 dominated structure, eventually inhibiting vitrification above 80 wt% addition of β-TCP or β-TC(Ga)P. 27 Al NMR shows [Al(PO 4 ) n ] species with dominant n =4 and 11 B NMR shows the 4-coordinated boron fraction in NABP falls from 0.7 to 0.1 on addition of the crystal hosts. Devitrification of glasses with 60–70 wt% crystal additions shows that Na + and Al 3+ from the encapsulant substitute for ∼20% of Ca 2+ in the β-TCP phase formed from the β-TCP:NABP glasses whilst ∼85% of Ga 3+ resubstitutes into β-TCP from the β-TC(Ga)P:NABP glasses. This demonstrates the preference for Ga 3+ substitution over Al 3+ in the Ca(5) site. [ABSTRACT FROM AUTHOR]

Treatment of 1,2-C 6 H 4 (SiH 3 )(SiH 3 ) (1) with Pt(dcpe)(PEt 3 ) 2 (dcpe = Cy 2 PCH 2 CH 2 PCy 2 ) in dry toluene at room temperature in the ratio of 1:1 leads to the complex {1,2-C 6 H 4 (SiH 2 )(SiH 2 )}Pt II (dcpe) (2) , which can react with proton organic reagent bearing hydroxy group with low steric hindrance to form a tetra-alkoxy substituted silyl platinum( II ) compound ( 3) . The structures of complexes (2) and (3) were unambiguously determined by multinuclear NMR spectroscopic studies and single crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

Treatment of 1,2-C6H4(SiH3)(SiH3) ( 1) with Pt(dmpe)(PEt3)2 (dmpe=Me2PCH2CH2PMe2) in the ratio of 1:1 leads to the complex {1,2-C6H4(SiH2)(SiH2)}PtII (dmpe) ( 2), which can react with proton organic reagent bearing hydroxy group with low steric hindrance to form a tetra-alkoxy substituted silyl platinum(II) compound ( 3). Compounds 2 and 3 are the very rare examples of silyl transition-metal complexes derived from this chelating hydrosilane ligand. To the best of our knowledge, there are only 6 examples of silyl metal complexes prepared from this ligand with such structural features registered in the Cambridge Structural Database, among them, only one silyl platinum(II) compound is presented. The structures of complexes 2 and 3 were unambiguously determined by multinuclear NMR spectroscopic studies and single crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

[MediaObject not available: see fulltext.]The reaction of bromoacetone and hydroxylamine- О-sulfonic acid with isomeric mono- and dinitropyrazoles containing a furazanyl moiety at position 3(5) gave pairs of regioisomeric products from pyrazole ring N-acetonylation and N-amination, respectively, that were characterized in detail by multinuclear NMR spectroscopy. X-ray structural study of the four synthesized N-amino derivatives indicated a non-planar structure, while the conformational analysis pointed to conformational lability of such molecules, and the role of intermolecular interactions in determining the crystal structure. [ABSTRACT FROM AUTHOR]

A series of new (E)-3(5)-[β-(aryl)-ethenyl]-5(3)-phenyl-1H-pyrazoles bearing fluorine atoms at different positions of the aryl group have been synthesized starting from the corresponding β-diketones. All compounds have been characterized by elemental analysis, DSC as well as NMR (1H, 13C, 19F and 15N) spectroscopy in solution and in solid state. Three structures have been solved by X-ray diffraction analysis, confirming the tautomeric forms detected by solid state NMR. The in vitro study of their inhibitory potency and selectivity on the activity of nNOS and eNOS (calcium-calmodulin dependent) as well as iNOS (calcium-calmodulin independent) isoenzymes is presented. A qualitative structure-activity analysis allowed the establishment of a correlation between the presence/absence of different substituents with the inhibition data proving that fluorine groups enhance the biological activity. (E)-3(5)-[â-(3-Fluoro-4-hydroxyphenyl)-ethenyl]-5(3)-phenyl-1Hpyrazole (13), is the best inhibitor of iNOS, being also more selective towards the other two isoforms. [ABSTRACT FROM AUTHOR]

[Figure not available: see fulltext.] A general method has been developed for the synthesis of 1-pyrazolyl-1 Н-tetrazoles, and N-nitration of these compounds was studied. The structural features affecting the direction of nitration were identified. A series of 1-( N-nitropyrazolyl)-1 Н-tetrazoles was obtained, representing a new type of heteronuclear N-nitropyrazole derivatives. [ABSTRACT FROM AUTHOR]

23 Na, 35 Cl, 81 Br, and 87 Rb NMR have been applied to clarify the influence of electrostatic and hydrophobic interactions on the counterion binding equilibria of weakly acidic and basic polyelectrolytes with negatively and positively charged polyions, respectively. Na + and Rb + ions capable of binding to weakly acidic polymers (i.e., polyacrylate acid (PAA)), and Cl − and Br − ions capable of binding to weakly basic polymers (i.e., poly(N-vinylimidazole) (PVIm) and polyallylamine (PAAm)) were used as representative examples to measure these interactions. The results revealed that the longitudinal and transverse NMR relaxation rates of the Cl − , Br − and the Rb + counterions in the PVIm and PAA systems were faster than those of free Cl − , Br − and Rb + ions when the polyions were completely neutralized. The binding interactions between the Cl − , Br − and the Rb + ions and PVIm and PAA were found to be hydrophobic in nature because the magnitudes of these effects were found to be dependent on the hydrophobicities of the polyelectrolytes and the counterions. Although a slight hydrophobic interaction was detected between the Rb + ions and PAA, where the degree of neutralization of the polyacid ( α ) was 1, Na + ions also started to bind to PAA at α = 0.65, where the linear charge density corresponded to the Bjerrum length. [ABSTRACT FROM AUTHOR]

195Pt and 1H NMR has been used to show that addition of chlorine and bromine to [Pt(CN)4]2_ in presence of perchloric acid in water results in cyanide and water scrambling with formation of eleven complexes of the type [Pt(CN)4-nCl(H2O)n+1](n-1)+ (n=0, 1, 2, 3, 4). Addition of NBu4OH to this solution gives (NBu4)2[Pt(CN)4Cl(OH)]. NMR measurements in acetone also show cyanide and hydroxyl group scrambling with formation of complexes of the type [Pt(CN)4-nCl(OH)n+1]2-, (n=0, 1, 2, 3, 4).

Treatment of the unsymmetric disilane (SiH 3 ) (SiMeBu t 2 ) (1) containing one Si–Si single bond with Pt(dcpe) (PEt 3 ) 2 (dcpe = Cy 2 PCH 2 CH 2 PCy 2 ) in the ratio of 1:1 leads to a stable disilanylplatinum hydride complex {(SiH 2 ) (SiMeBu t 2 )}(H)– Pt Ⅱ (dcpe) (2) , which is one of the very few examples of bis(phosphine) (hydrido) platinum(Ⅱ) complexes bearing silyl ligands with Si–Si single bonds structurally characterized by single crystal X-ray analysis and multinuclear NMR spectroscopic studies. [ABSTRACT FROM AUTHOR]

Structures of the main resonance and tautomeric forms of three Schiff bases of 2-hydroxy-1-naphthaldehyde (1OXA), 5-bromosalicylaldehyde (2OXA) and 5-nitrosalicylaldehyde (3OXA) with 1,8-diamine-3,6-dioxaoctane, before and after protonation and complexation of monovalent metal cations, have been studied by FTIR, H, C and N NMR methods. The spectroscopic investigations provided clear evidence that the Schiff bases exist in acetonitrile solution as three different tautomers: 1OXA in enamine-oxo, 2OXA in imine-hydroxy and 3OXA in a low-barrier O···H···N imine-oxo forms. It was found on the basis of multinuclear NMR studies, that in solid state, the enamine-oxo and imine-hydroxy tautomers are formed exclusively, but not the untypical imine-oxo tautomer, which requires strong stabilisation by solvent molecules in solution. MOG-PM6 calculations of the different tautomers allowed visualisation of their energetically the most favourable structures. Protonation of 1OXA-3OXA Schiff bases leads to formation of common forms, i.e. protonated imine-hydroxy structure, irrespectively of the structure of tautomer before protonation. In turn, coordination of monovalent metal cations implies common formation of zwitterionic forms within all studied ligands in solution. Application of FT-IR and NMR titrations in combination with ESI MS spectrometry revealed the nature and the structure of OXA complexes, whose formation is impeded by the intra- and intermolecular interactions. MOG-PM6 calculations allowed visualisation of Li and Na metal coordination sphere geometries within structure of all investigated complexes, stabilised by intermolecular interactions with solvent molecules. [ABSTRACT FROM AUTHOR]

The platinum(II) oxalato complexes [Pt(ox)(naza)2] (1-3) were synthesized and characterized by elemental analysis (C, H, N), multinuclear NMR spectroscopy (¹H, 13C, 15N, 195Pt) and electrospray ionization mass spectrometry (ESI-MS); naza = 4-chloro-7-azaindole (4Claza; 1), 3-bromo-7-azaindole (3Braza; 2) or 4-bromo-7-azaindole (4Braza; 3). The prepared substances were screened for their in vitro antitumor activity on the osteosarcoma (HOS) and breast adenocarcinoma (MCF7) human cancer cell lines, where 2 showed moderate antitumor effect (IC50 = 27.5 μM, and 18.3 μM, respectively). The complex 2 was further tested on a panel of six others human cancer cell lines, including the malignant melanoma (G361), cervix carcinoma (HeLa), ovarian carcinoma (A2780), cisplatin-resistant ovarian carcinoma (A2780R), lung carcinoma (A549) and prostate adenocarcinoma (LNCaP). This substance was found to be moderate antitumor effective against G361 (IC50 = 17.3 μM), HeLa (IC50 = 31.8 μM) and A2780 (IC50 = 19.2 μM) cell lines. The complex 2 was also studied by NMR for its solution stability and by ESI-MS experiments for its ability to interact with biomolecules, such as cysteine, glutathione or guanosine 5′-monophosphate. [ABSTRACT FROM AUTHOR]

A one-step synthetic procedure using the reaction of potassium bis(oxalato)platinate(II) with the corresponding N6-benzyladenosine derivative (nL) provided the [Pt(ox)(nL)2]·1.5H2O oxalato (ox) complexes 1-5, involving the nL molecules as monodentate coordinated N-donor ligands. The complexes were thoroughly characterized by elemental analysis, multinuclear (1H, 13C, 15N, 195Pt) and two dimensional NMR, infrared and Raman spectroscopy, and mass spectrometry, proving their composition and purity as well as coordination of nL through the N7 atom of the purine moiety. Geometry of [Pt(ox)(4FL)2] (5) was optimized at the B3LYP/LANLTZ/6-311G** level of theory. The complexes were screened for their in vitro cytotoxicity against two human cancer cell lines (HOS osteosarcoma and MCF7 breast adenocarcinoma), but they did not show any effect up to the concentration of 50.0 μM (compounds 1, 2) or 20.0 μM (compounds 3-5). [ABSTRACT FROM AUTHOR]

Abstract: Treatment of (SiH2)(SiMe2 t Bu)2 (1), (SiH3)SiH(SiMe2 t Bu)2 (2) with Pt(dcpe)(PEt3)2 (dcpe = Cy2PCH2CH2PCy2) in the ratio of 2:1:1 in one pot leads to a novel complex {(SiH)(SiMe2 t Bu)2}(SiH3)PtII(dcpe) (3), which is the first example of bis(silyl) platinum(II) complex bearing a SiH3 ligand structurally characterized by single crystal X-ray analysis and multinuclear NMR spectroscopic studies. H2Si(SiMe2 t Bu)2 for 1, HSi(SiH3)(SiMe2 t Bu)2 for 2, Pt(dcpe)(SiH3)[SiH(SiMe2 t Bu)2] for 3 throughout the manuscript. [Copyright &y& Elsevier]

The reaction of dichlorostannanes RSnCl (R=Me 1, Bu 2) with piperazine ligand in molar ratio 1:2, in dry methylene dichloride, in an inert atmosphere leads to the synthesis of RSn(CHN)(R=Me 1, Bu 2). In a similar manner, The reaction between PhSnCl and piperazine in dry ethanol in molar ratio 1:1 produces [PhSn(CHN)] (3). The yields of these new products were excellent and they have been fully characterized by FT-IR, UV-Vis, multinuclear (H, C, Sn) NMR spectroscopy and mass spectrometry, as well as elemental analysis. The spectroscopic results indicate that the piperazine ligand is coordinated to tin atom of organotin moieties, through the nitrogen atoms. Furthermore, the ligand behaves as a bidentate fashion in (1) and (2) and gives 1:2 substitution products, while in the complex (3) the two six-membered rings bind in bidentate-chelate forms between the two Sn atoms. [ABSTRACT FROM AUTHOR]

The platinum(II) complexes trans-[PtCl2(Ln)2].xSolv 1-13 (Solv = H2O or CH3OH), involving N6-benzyladenosine-based N-donor ligands, were synthesized; Ln stands for N6-(2-methoxybenzyl)adenosine (L1, involved in complex 1), N6-(4-methoxybenzyl) adenosine (L2, 2), N6-(2-chlorobenzyl)adenosine (L3, 3), N6-(4-chlorobenzyl)- adenosine (L4, 4), N6-(2-hydroxybenzyl)adenosine (L5, 5), N6-(3-hydroxybenzyl)- adenosine (L6, 6), N6-(2-hydroxy-3-methoxybenzyl)adenosine (L7, 7), N6-(4-fluorobenzyl) adenosine (L8, 8), N6-(4-methylbenzyl)adenosine (L9, 9), 2-chloro-N6-(3-hydroxybenzyl) adenosine (L10, 10), 2-chloro-N6-(4-hydroxybenzyl)adenosine (L11, 11), 2-chloro- N6-(2-hydroxy-3-methoxybenzyl)adenosine (L12, 12) and 2-chloro-N6-(2-hydroxy-5- methylbenzyl)adenosine (L13, 13). The compounds were characterized by elemental analysis, mass spectrometry, IR and multinuclear (1H-, 13C-, 195Pt- and 15N-) and two-dimensional NMR spectroscopy, which proved the N7-coordination mode of the appropriate N6-benzyladenosine derivative and trans-geometry of the title complexes. The complexes 1-13 were found to be non-toxic in vitro against two selected human cancer cell lines (HOS and MCF7; with IC50 > 50.0 μM). However, they were found (by ESI-MS study) to be able to interact with the physiological levels of the sulfur-containing biogenic biomolecule L-methionine by a relatively simple 1:1 exchange mechanism (one Ln molecule was replaced by one L-methionine molecule), thus forming a mixed-nitrogen/sulfur-ligand dichlorido-platinum(II) coordination species. [ABSTRACT FROM AUTHOR]

Abstract: The platinum(II) dichlorido and oxalato complexes of the general formula cis-[PtCl2(nHaza)2] (1–3) [Pt(ox)(nHaza)2] (4–6) involving 7-azaindole halogeno-derivatives (nHaza) were prepared and thoroughly characterized. A single-crystal X-ray analysis of cis-[PtCl2(3ClHaza)2]·DMF (1·DMF; 3ClHaza symbolizes 3-chloro-7-azaindole) revealed a distorted square-planar arrangement with both the 3ClHaza molecules coordinated through their N7 atoms in a cis fashion. In vitro cytotoxicity of the complexes was evaluated by an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay against the HOS (osteosarcoma), MCF7 (breast adenocarcinoma) and LNCaP (prostate adenocarcinoma) human cancer cell lines. The dichlorido complexes 1–3 (IC50 =3.8, 3.9, and 2.5μM, respectively) showed significantly higher in vitro anticancer effect against HOS as compared with cisplatin, whose IC50 =37.7μM. The biological effect of cisplatin against MCF7 (IC50 =24.5μM) and LNCaP (IC50 =3.8μM) was also exceeded by 1–3 (except for 2 against LNCaP), but the difference can be classified as significant only in the case of 1 (IC50 =3.4μM) and 3 (IC50 =2.0μM) against MCF7. The molecular pharmacological studies (RNA synthesis by T7 RNA polymerase in vitro) proved that 1–3 bind to DNA in a similar manner as cisplatin, since the RNA synthesis products of 1–3 and cisplatin showed a similar sequence profile of major bands. [Copyright &y& Elsevier]