Topic
Aquation
About: Aquation is a research topic. Over the lifetime, 1443 publications have been published within this topic receiving 17507 citations.
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TL;DR: Piano stool ruthenium complexes of the composition [Ru(II)(η6‐arene)(en)Cl]+/2+ (en = ethylenediamine) represent an emerging class of cisplatin‐analogue anticancer drug candidates and computational quantum chemistry is used to characterize the structure, stability and reactivity of these compounds.
Abstract: Piano stool ruthenium complexes of the composition [Ru(II)(η6-arene)(en)Cl]+/2+ (en = ethylenediamine) represent an emerging class of cisplatin-analogue anticancer drug candidates. In this study, we use computational quantum chemistry to characterize the structure, stability and reactivity of these compounds. All these structures were optimized at DFT(B3LYP)/6-31G(d) level and their single point properties were determined by the MP2/6-31++G(2df,2pd) method. Thermodynamic parameters and rate constants were determined for the aquation process, as a replacement of the initial chloro ligand by water and subsequent exchange reaction of aqua ligand by nucleobases. The computations were carried out at several levels of DFT and ab initio theories (B3LYP, MP2 and CCSD) utilizing a range of bases sets (from 6-31G(d) to aug-cc-pVQZ). Excellent agreement with experimental results for aquation process was obtained at the CCSD level and reasonable match was achieved also with the B3LYP/6-31++G(2df,2pd) method. This level was used also for nucleobase-water exchange reaction where a smaller rate constant for guanine exchange was found in comparison with adenine. Although adenine follows a simple replacement mechanism, guanine complex passes by a two-step mechanism. At first, Ru-O6(G) adduct is formed, which is transformed through a chelate TS2 to the Ru-N7(G) final complex. In case of guanine, the exchange reaction is more favorable thermodynamically (releasing in total by about 8 kcal/mol) but according to our results, the rate constant for guanine substitution is slightly smaller than the analogous constant in adenine case when reaction course from local minimum is considered. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
33 citations
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33 citations
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TL;DR: In this article, a near uV-visible range photolysis of cis-Ru{sup II}(NH{sub 3}{sub 4}(L){sub 2} (: = pyridine (py), 4-picoline (4-pic), isonicotinamide (isn), or 4-acetylpyridine(4-acpy)) and cis-R-sup II{sup III{sub 5}(R.
Abstract: Near uV-visible range photolysis of cis-Ru{sup II}(NH{sub 3}){sub 4}(L){sub 2} (: = pyridine (py), 4-picoline (4-pic), isonicotinamide (isn), or 4-acetylpyridine (4-acpy)) and cis-Ru{sup II}(NH{sub 3}){sub 4}(isn)(L) (L = py, 4-pic, pyrazine, or 4-acpy) lead to isn, L, and ammonia aquation. The complexes were irradiated at 313, 365, 405, 436, 480, and 519 nm, in acidic (pH 3.5-4.0) aqueous solution and with {approximately} 10{sup {minus}3} M Ru complex concentration. The cis complexes have ligand field (LF) and metal-to-ligand charge-transfer (MLCT) states as the lowest energy excited states. The relative yields of the photoreactions of the cis complexes show patterns consistent with the excited-state tuning model proposed to explain photochemical properties of the pentaammine analogues, Ru{sup II}(NH{sub 3}){sub 5}(L), which undergo photosubstitution when LF is the lowest energy excited state, as is also the case for the trans complexes. For each cis complex, a fixed ratio of released ligands is observed at all irradiation wavelengths studied, this being a strong evidence that the observed photoreactions occur from one single LF excited state, or an ensemble of equilibrated LF excited states of the same electronic configuration. Ligands are more easily labilized along the axis with the weaker {pi}-acceptor ability. For a particular axis,more » the ligand with lower {pi}-acceptor ability is more easily labilized. 18 refs., 3 figs., 5 tabs.« less
33 citations
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32 citations
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TL;DR: In this paper, the formation of iridium(IV) [Ir(IV)] in hydrochloric acid solutions at different proton concentrations (between 1 and 10 −3 M ) has been studied using capillary zone electrophoresis and spectrophotometry in order to determine the number of species that are formed during the aquation and hydrolysis of the hexachloro complex of Ir(IV).
32 citations