- Molecular interaction fields vs. quantum-mechanical-based descriptors in the modelling of lipophilicity of platinum(iv) complexes
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We report QSAR calculations using VolSurf descriptors to model the lipophilicity of 53 Pt(iv) complexes with a diverse range of axial and equatorial ligands. Lipophilicity is measured using an efficient HPLC method. Previous models based on a subset of these data are shown to be inadequate, due to incompatibility of whole molecule descriptors between carboxylato and hydroxido ligands. Instead, the interaction surfaces of complexes with various probes are used as independent descriptors. Partial least squares modelling using three latent variables results in an accurate (R2 = 0.92) and robust model (Q2 = 0.87) of lipophilicity, that moreover highlights the importance of size and hydrophobicity terms and the modest relevance of hydrogen bonding.
- Ermondi, Giuseppe,Caron, Giulia,Ravera, Mauro,Gabano, Elisabetta,Bianco, Sabrina,Platts, James A.,Osella, Domenico
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supporting information
p. 3482 - 3489
(2013/03/28)
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- Trend in cytotoxic activity of a series of cis-[APtCl2] (A = ethylenediamine methylated at different positions) complexes
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The study of a series of cis-[APtCl2] complexes (A = ethylenediamine, en, methylated at different positions) was carried out to evaluate the effect of different methyl substitutions on the cytotoxic properties of the resulting derivatives. As expected, differentially methylated complexes were found to differ widely in their cytotoxic effects on human cultured ovarian carcinoma cells (A2780). Molecular mechanics (MM) calculations have been performed to assess the relationship between differential diamine methylation and the repulsive energy of the corresponding complexes when interacting with DNA. Compounds that bind DNA at high energetic cost relative to cisplatin, due to the steric hindrance of additional methyl groups, have shown high values for IC50 (concentration inhibiting tumour cell growth by 50%). Semi-quantitative analyses with a DNA electrochemical biosensor confirm that the interaction between cis-[APtCl2] complexes and ds-DNA deposed onto the electrode is stronger for the non-methylated derivative with respect to the fully methylated congener. In addition, MM calculations were used to investigate the interactions between DNA and cis-[(P-L-A)PtCl2] complexes [A = en group linked to an antiestrogen-like pharmacophore, P, via a -(CH2)n- spacer (n = 2, 4, 6, 8 and 10), L].
- Milanesio, Marco,Monti, Elena,Gariboldi, Marzia Bruna,Gabano, Elisabetta,Ravera, Mauro,Osella, Domenico
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p. 2803 - 2814
(2009/02/03)
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- Reaction of dichloro(N-methylethylenediamine)platinum(II) PtmenCl 2 with iodine: The crystal structure of mixed-valence compound {[PtI4][PtI6]}[(CH3)2NH 2]4
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The reaction of dichloro(N-methylethylenediamine)platinum(II) with iodine gave {[PtI4][PtI6]}[(CH3)2NH 2]4 (I). Compound I was studied by X-ray diffraction. The crystals are triclinic, a = 7.833(2) ?, b = 8.889(2) ?, c = 13.737(3) ?, α = 97.65(3)°, β = 97.46(3)°, γ = 114.13(3)°, V = 857.0(3) ?3, Z = 1, space group P1 , R = 0.047 over 1431 reflections. This is a class I anionic mixed-valence compound. It is built of isolated centrosymmetrical square (platinum(II)) and octahedral (platinum(IV)) complexes, [PtI4]2- and [PtI 6]2-, respectively, and dimethylammonium cations. Average PtII-I and PtIV-I distances are 2.608(2) and 2.673(2) ?, respectively. The structural units in the crystal are combined by a hydrogen-bond array.
- Fedotova,Minacheva,Kuznetsova
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p. 1163 - 1167
(2008/10/08)
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- Atom-transfer and outer-sphere reductions of platinum(IV) complexes. A comparative kinetic investigation
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Reductions of platinum(IV) complexes of the type (N-N=en, meen, dmen, tmen, 1,2-pn, 1,3-pn) by FeCp2, Bu4NI and (ClO4)2 in the presence of Et4NCl have been kinetically investigated in methanol solution.The reactions with FeCp2 or Bu4NI obey e second-order rate law reductant), whereas the rate law for the reactions with (ClO4)2 in the presence of Et4NCl is: rate = Pt(II)+kPt(II)->2+4>.The reactivity of the complexes is enhanced by an increased steric hindrance of the N-N ligand.Such a reactivity trend is likely to be related to a parallel increased thermodynamic tendency of platinum(IV) towards reduction.The effect of steric hindrance on the rate is less pronounced in the reaction with 2+ probably due to a direct interaction between the N-N and the NH2Et ligands in the activated complex
- Peloso, Arnaldo,Mohamud, Sacid Issa
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p. 349 - 354
(2007/10/02)
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