112 research outputs found
Reactivity of platinum(II) triphenylphosphino complexes with nitrogen donor divergent ligands
Dinuclear platinum(II) complexes [{PtCl2(PPh3)}2(μ-N–N)], where N–N is a divergent bidentate nitrogen ligand, were prepared by reacting cis-[PtCl2(PPh3)(NCMe)] with N–N in a Pt/N–N molar ratio 2. The (trans,trans)-isomers were obtained as kinetic products and recovered in good yields and high purity {1, N–N = pyrazine (pyrz); 2, N–N = 4,4′-bipyridyl (bipy); 3, N–N = piperazine (pipz); 4, N–N = p-xylylendiamine (xylN2)}. Cis-[PtCl2(PPh3)(NCMe)] was also reacted with the tridentate divergent ligand 2,4,6-tris-(pyrid-4′-yl)1,3,5-triazine (py3TRIA) in molar ratio 3 with formation of the trinuclear (trans,trans,trans)-[{PtCl2(PPh3)}3(μ-py3TRIA)], 5. On the other hand, the treatment of cis-[PtCl2(PPh3)(NCMe)] with the monodentate pyridine (py) produced a mixture of both trans-[PtCl2(PPh3)(py)] (6a) and cis-[PtCl2(PPh3)(py)] (6b). The reactions of cis-[PtCl2(PPh3)(NCMe)] with N–N = pyrz, bipy, pipz, carried out with a Pt/N–N molar ratio 1, were monitored by 31P NMR spectroscopy. Equilibria were observed in solution, involving dinuclear (trans–trans)-[{PtCl2(PPh3)}2(μ-N–N)], mononuclear [PtCl2(PPh3)(N–N)] and free N–N. The addition of an excess of the divergent ligand allowed the complete conversion to the corresponding mononuclear complexes. With the heteroaromatic ligands both geometric isomers were observed (7a, 7b and 8a, 8b, for pyrz and bipy derivatives, respectively) while with pipz the trans-isomer only was detected, 9. In the system involving bipy, the scarcely soluble dinuclear (cis,cis)-[{PtCl2(PPh3)}2(μ-bipy)], 2b, was also obtained. Products 2, 2b, 3·2(CHCl3) and 6a·0.5(C2H4 Cl2) were structurally characterized by single crystal X-ray diffraction methods
Synthesis and reactivity of platinum(II) triphenylphosphino complexes with aromatic aldoximes
trans-[Pt(μ-Cl)Cl(PPh3)]2 reacted with arylaldoximes in 1,2-dichloroethane to afford [PtCl2(PPh3){N(OH)=CHAr}] (Ar = 3,4-dimethoxyphenyl, 1-naphthyl, 9-anthryl) where aldoxime ligands are N-coordinated to platinum. The obtained complexes are soluble in chlorinated solvents, where they afford equilibrium mixtures of cis,trans and/or (E),(Z) isomers. Equilibria in solution were studied by 31P-NMR spectroscopy and solid state structural data were obtained by single crystal X ray diffraction studies. The reactivity of [PtCl2(PPh3){N(OH)=CHAr}] complexes with basic aqueous solutions was studied, under liquid-liquid phase transfer catalysis conditions. The outcome of the reaction depends on the stereochemistry of the precursors: cis,(Z)-isomers promptly undergo cyclization to the corresponding dinuclear derivatives [Pt{μ-(2-N,O)}- {N(O)=CHAr}Cl(PPh3)]2, where two aldoximate ligands symmetrically bridge two metal centers
A convenient synthesis of highly luminescent lanthanide 1D-zigzag coordination chains based only on 4,4′-bipyridine as connector
The coordination polymers View the MathML source·C7H8 (Ln = Eu, β-dik = dbm, tta, hfac; Ln = Tb; β-dik = dbm; Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac: hexafluoroacetylacetone) were easily assembled in mild conditions and high yields starting from the anhydrous lanthanide β-diketonates as nodes and 4,4′-bipyridine (bpy) as connector. X-ray single crystal studies have shown zigzag extended chains where lanthanide centres are 8-coordinated in a distorted square-antiprismatic geometry. Photoluminescence studies show bright red europium emission and spectral features dependent on the topology of the polymeric chains
Analyses of organochlorine pesticides residues in eels (Anguilla anguilla) from Lake Garda using Gas chromatography coupled with Tandem Mass Spectrometry (GC-MS/MS).
Lake Garda is located in Insubria region, that is known for being the most populated and industrialized area of Italy (Camusso et al., 2001). Therefore, the Lake water, and also the fish species present, could be affected by environmental contamination. European eel (Anguilla anguilla) are considered as suitable matrix for biomonitoring environmental contaminants in European water (Belpaire et al., 2007), being widespread in many European waters and highly contaminated by lipophilic compounds, due to the high lipid content (up to 40%) (Larsson et al., 1991). Moreover, eel is an edible species (its farming currently supplies approximately 45,000 tons/year) (Nielsen et al., 2008), so it also represents a public health issue. Based on these considerations, the aim of this study was to evaluate the occurrence of fourteen organochlorine pesticides (OCs) in forty-five eels (Anguilla anguilla) from Lake Garda, using Accelerated Solvent Extraction (ASE) procedure for the analytes extraction and Gas chromatography coupled with Tandem Mass Spectrometry (GC-MS/MS) for the analysis of OCs. GC-MS/MS analysis was developed and validated according to the SANTE/11945/2015 guidelines. Uncontaminated eel sample (previously checked for the presence of OCs and considered blank with a concentration of compounds < Limit of Detection) were used for all procedure's optimization steps. For all the OCs analysed, satisfactory results were achieved. Regarding eel samples, several pesticides were detected, but DDTs (DDT and its metabolites) were found with the highest prevalence (92 %). The concentration rage was from not detected (n.d.) to 19000 ng g-1. Although DDTs levels in the environment are declining (Albaiges et al., 2011), they continue to bioaccumulate in tissues of human and animal and biomagnify in food chains
Are saponins and sapogenins precursors of prednisolone? Preliminary results
The transformation of cortisol into prednisolone in cattle faeces was demonstrated and provided by literature, given the structural similarity of prednisolone with cortisol. In this study, we evaluated a possible neo-formation of prednisolone, as results of a faecal or environmental contamination. A saponine, α-solanine, and a sapogenin, diosgenin, were selected as possible precursors. A simple method without extraction was applied. The analyses were performed by HPLC–MSn to evaluate the possible transformations. The results showed that prednisolone was detected in the faecal suspension spiked with diosgenin at t= 8h, while cortisol was also detected at t = 24h in the sample of faeces spiked with α-solanine. In the feed and in the control samples, no transformations were observed
Synthesis and DNA binding tests of a fluorescent pyrene bearing a Pt(II) pyridineimino complex
Despite the long time gone respect to the discovery of cis-platinum anticancer activity, still a huge amount of research is devoted to the design of new Pt(II) complexes with enhanced biological activity [1-3].
The here presented work concerns the synthesis of a fluorescent pyridinimino platinum(II) complex, where the presence of a cis-platinum moiety linked to an extended aromatic residue could provide interesting properties as for binding to biosubstrates. In fact, covalent Pt(II) binding can occur, which would be strengthened by the anchoring offered by possible intercalation in nucleic acids of the pyrene fragment. Antiproliferative properties have been described for some pyridinimino [4] and pyridinamino [5] platinum(II) complexes. Moreover, similar bifunctional systems have already been tested with interesting performances [7,8].
The chelating iminopyridine ligand was prepared by a condensation reaction between pyridine-2-carboxyaldehyde and the suitably O-alkylated aminoalcohol. The platinum complex was then synthesized starting from cis-[PtCl2(DMSO)2], and purified by crystallization. The pure complex (elemental analysis) was spectroscopically (IR, 1H-, 13C and 195Pt NMR) characterized. It is well soluble in DMSO and in DMSO/H2O mixtures, where its stability was checked by 1H- and 195Pt NMR. The absorbance and fluorescence optical features of the dye were also checked.
Afterwards, the target Pt(II) complex was let interact with natural double stranded DNA to check its reactivity towards this biosubstrate. Spectrophotometric and spectrofluorometric titrations show that the binding does indeed occur. As for absorbance data, hypochromic and bathochromic effects suggest intercalative binding. However, the absence of a defined isosbestic point indicates multiple equilibria. Interestingly and in agreement with this observation, the light emission behavior of the dye/DNA system is complex. Opposite fluorescence change trends are observed at different temperatures, likely related to a different contribution of DNA-templated dye aggregation. Under the (until now) explored conditions, the binding is so strong to turn to be quantitative. Further experiments are ongoing to better enlighten the binding mechanism.
References:
[1] S. X. Chong, S. C. F. Au-Yeung, K. K. W. To, Current Medicinal Chemistry 2016, 23(12), 1268-12.
[2] L. Cai, C. Yu, L. Ba, Q. Liu, Y. Qian, B. Yang, C. Gao, Applied Organometallic Chemistry 2018, 32(4).
[3] M. Hanif, C. G. Hartinger, Future Medicinal Chemistry 2018, 10(6), 615-617.
[4] B. A. Miles, A. E. Patterson, C. M. Vogels, A. Decken, J. C. Waller, P. Jr. Morin, S. A. Westcott, Polyhedron 2016, 108, 23-29.
[5] S. Karmakar, K. Purkait, S. Chatterjee, A. Mukherjee, Dalton Trans. 2016, 45, 3599-3615.
[6] S. Hochreuther, R. van Eldik, Inorg. Chem., 2012, 51 (5), 3025-3038.
[7] C. Bazzicalupi, A. Bencini, A. Bianchi, T. Biver, A. Boggioni, S. Bonacchi, A. Danesi, C. Giorgi, P. Gratteri, A. Marchal Ingraín, F. Secco, C. Sissi, B. Valtancoli, M. Venturini, Chemistry – A European Journal 2008, 14(1), 184-196.
[8] S. Biagini, A. Bianchi, T. Biver, A. Boggioni, I.V. Nikolayenko, F. Secco, M. Venturini, Journal of Inorganic Biochemistry 2011, 105, 558-562
Создатели ядерного щита
The first example of a crystallographically established bis-adduct of tridentate 2,2':6',2:6',2"'-quaterpyridine (qtpy) of formula [Fe(qtpy)(2)][ClO4](2) has been obtained by treating an aqueous solution of iron(II) perchlorate with the ligand in the presence of triethylamine
Determination of thyreostats in bovine urine and thyroid glands by HPLC-MSMS
Thyreostats are orally active substances used in medicine and veterinary work to regulate the production of T3 and T4 hormones by the thyroid gland. They can be illicitly administered to livestock for fattening purposes in order to improve body-weight gain due to an important retention water in edible tissues and in the gastroenteric tract. Their fraudulent utilisation is severely prohibited by the European Union, which requires a precise monitoring. In 2007, European Union of Reference Laboratories in the CRL Guidance paper proposed a recommended concentration of 10 ng mL-1 in urine, which has just been suggested to increase to 30 ng mL-1. In order to facilitate the detection of thyreostats in two bovine matrices, urine and thyroid glands, a method was developed without a previous derivatisation step, frequently used for HPLC analysis of Thiouracil. A salting-out assisted liquid–liquid extraction procedure for preparation was carried out to facilitate the movement of the thyreostats to the tert buthyl methyl ether phase. The HPLC-MS/MS analytical procedure of the method was validated according to the guidelines of Commission Decision 2002/657/EC and has permitted to obtain satisfactory performance parameters and, decision limit and detection capability values for all the thyreostats lower than the recommended values hitherto mentioned
New trans dichloro (triphenylphosphine)platinum(II) complexes containing N-(butyl),N-(arylmethyl)amino ligands: Synthesis, cytotoxicity and mechanism of action
Some new platinum(II) complexes have been prepared, of general formula trans-[PtCl2(PPh3)NH(Bu)CH2Ar], where the dimension of the Ar residue in the secondary amines has been varied from small phenyl to large pyrenyl group. The obtained complexes, tested in vitro towards a panel of human tumor cell lines showed an interesting antiproliferative effect on both cisplatin-sensitive and -resistant cells. For the most cytotoxic derivative 2a the investigation on the mechanism of action highlighted the ability to induce apoptosis on resistant cells and interestingly, to inhibit the catalytic activity of topoisomerase II
Insights into the Redox Activity of Platinum(II) Complexes Bearing a Mitochondriotropic Ligand in Cisplatin-resistant Ovarian Cancer Cell Lines
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