Two dumbbell-shaped components with tetraarylmethane-type stoppers - one hydrophobic and one hydrophilic - and a rod-like section containing a tetrathiafulvalene (TTF) unit and a 1,5-dioxynaphthalene (DNP) moiety as electron-donating units, and their [2]rotaxanes, incorporating the cyclobis(paraquat-p-phenylene) (CBPQT4+) cyclophane as their electron-accepting ring component, have been synthesized, the latter using template-directed protocols. The two amphiphilic [2]rotaxanes, which differ from each other only in the lengths of the polyether chains associated with their hydrophilic stoppers, were designed in order (i) to have them exhibit enhanced amphiphilicities and, by altering the lengths of polyether chains, (ii) to improve the qualities of their Langmuir-Blodgett films, and by removing the phenolic residues, (iii) to increase the oxidative stabilities of these switchable molecules, and so extend the lifetimes of electronic devices fabricated from amphiphilic hysteretic molecular switches of this type. UV-VIS absorption and 1H NMR spectra, as well as electrochemical measurements, show that both [2]rotaxanes exist to all intents and purposes in solution as the translational isomer in which the CBPQT4+ cyclophane surrounds the TTF unit. Evidence has also been obtained for the presence in solution of folded conformations of these [2]rotaxanes. While ox/red stimulation of the TTF unit causes shuttling of the CBPQT4+ cyclophane between the TTF and DNP stations, reduction of CBPQT4+ causes unfolding of the [2]rotaxane molecules.
两个哑铃形状的组分,带有四芳基甲烷型堵头-一个疏水性和一个亲水性-以及一个包含四硫富瓦烯(TTF)单元和1,5-二氧基萘(DNP)基团作为电子给体单元的棒状部分,以及它们的[2]轮烷,包括环对苯二甲氧基苯并环(CBPQT4+)环状分子作为它们的电子受体环组分,已经被合成,后者使用模板定向协议。这两个两性[2]轮烷仅在与其亲水性堵头相关的聚醚链的长度上不同,旨在(i)使它们表现出增强的两性特性,并通过改变聚醚链的长度(ii)提高其Langmuir-Blodgett膜的质量,并通过去除酚残基(iii)增加这些可切换分子的氧化稳定性,从而延长制造从这种类型的两性滞后分子开关的电子器件的寿命。 UV-VIS吸收和1H NMR光谱以及电化学测量表明,两个[2]轮烷在溶液中实质上存在于CBPQT4+环状分子包围TTF单元的平移异构体中。还获得了这些[2]轮烷的折叠构象在溶液中的存在证据。虽然TTF单元的氧化/还原刺激引起CBPQT4+环状分子在TTF和DNP站之间穿梭,但CBPQT4+的还原导致[2]轮烷分子的展开。