Ferrocene and Silicon-Containing Oxathiacrown Macrocycles and Linear Oligo-Oxathioethers Obtained via Thiol鈥揈ne Chemistry of a Redox-Active Bifunctional Vinyldisiloxane

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• 作者：Sonia Bru帽a ; Ignacio Mart铆nez-Montero ; Ana M^a Gonz谩lez-Vadillo ; Carlos Mart铆n-Fern谩ndez ; M. Merced Montero-Campillo ; Otilia M贸 ; Isabel Cuadrado
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：October 13, 2015
• 年：2015
• 卷：48
• 期：19
• 页码：6955-6969
• 全文大小：843K
• ISSN：1520-5835

文摘

The application of 1,3-divinyl-1,3-dimethyl-1,3-diferrocenyldisiloxane [(CH₂鈺怌H)FcMeSi]₂O (1) as an efficient electroactive vinylsilane precursor for thiol鈥揺ne radical reactions is described. In order to determine if steric or electronic limitations due to the redox-active metallocene moiety might affect the bis(hydrothiolation) of the bifunctional vinylsilane, a model reaction was initially performed between 1 and 2-mercaptoethanol, resulting in the formation of the newly sulfur-containing carbosiloxane 2 in excellent yield. The bis(thiol鈥揺ne) reaction of 1 was successfully extended to 2,2鈥?(ethylenedioxy)diethanethiol, affording a series of novel precisely defined, redox-active oxathiacrown macrocycles (3 and 4_n) and sulfur-bearing linear oligo-carbosiloxanes (5_n and 6_n) with a backbone in which the 鈭扴(CH₂)₂鈥揙(CH₂)₂O鈥?CH₂)₂S鈥?chain and the 鈭扴i鈥揙鈥揝i鈥?bond, bearing pendant ferrocenes, are alternately linked by ethylene bridges. These reactions have been initiated either thermally (in toluene solution with AIBN) or by UV light irradiation in THF in the presence of 2,2-dimethoxy-2-phenylacetophenone (DMPA) as photoinitiator, even though UV photoinitiated thiol鈥揺ne reactions were found to be the most efficient hydrothiolations. All newly silicon-containing oxathioether-based ferrocenyl compounds 2鈥?b>6_n have been thoroughly characterized using a combination of elemental analysis, multinuclear NMR spectroscopy, FT-IR, and MALDI-TOF mass spectrometry to establish their chemical structures and chain-end functionalities. The electrochemical behavior of 2鈥?b>6_n has been examined by cyclic and square wave voltammetries, in dichloromethane solution using [PF₆]^{鈭?/sup> and [B(C₆F₅)₄]鈭?/sup> as supporting electrolyte anions of different coordinating ability. The sulfur-rich cyclic and linear oligomers 4_n鈥?b>6_n exhibit excellent chemisorption properties and spontaneously form robustly adsorbed electroactive films onto Au or Pt electrode surfaces. The cation complexation ability of diferrocenyl silaoxathiacrown ether 3 has been studied using electrochemical and 1H NMR spectroscopic techniques. The voltammetric behavior of receptor 3 has proved to be very sensitive to the presence of Hg2+ cation. The ability of macrocycle 3 to bind Hg2+ has also been investigated through electronic structure calculations, being the interaction between the cation and one of the cyclopentadienyl rings the responsible of the different behavior of both redox-active centers.}