Unusual Behaviour of Donor-Acceptor Stenhouse Adducts (DASA) in Confined Space of a Water Soluble PdII8 Molecular Vessel,Journal of the American Chemical Society

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Unusual Behaviour of Donor-Acceptor Stenhouse Adducts (DASA) in Confined Space of a Water Soluble PdII8 Molecular Vessel
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2019-05-03 , DOI: 10.1021/jacs.9b03924
Rupak Saha ₁ , Anthonisamy Devaraj ₁ , Soumalya Bhattacharyya ₁ , Soumik Das ₁ , Ennio Zangrando ₂ , Partha Sarathi Mukherjee ₁

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Donor-acceptor Stenhouse adducts (DASA) are new-generation photochromic compounds discovered recently. DASA exist normally in open form (blue/violet) and readily convert to cyclic (light yellow/colorless) zwitterionic form reversibly in the presence of green light in toluene/dioxane. In aqueous medium, the open form is not stable and converts to the cyclic zwitterionic form irreversibly. We report here a new self-assembled Pd8 molecular vessel (MV) that can stabilize and store the open form of DASA even in aqueous medium. Reaction of the 90° acceptor cis-(tmeda)Pd(NO3)2 (M) [tmeda = N, N, N', N'-tetramethylethane-1,2-diamine] with a symmetric tetraimidazole donor (L, 3,3',5,5'-tetra(1 H-imidazol-1-yl)-1,1'-biphenyl) in a 2:1 molar ratio yielded a water-soluble [8+4] self-assembled M8L4 molecular barrel (MV). This barrel (MV) is found to be a potential molecular vessel to store and stabilize the open forms of DASA in aqueous medium over the more stable zwitterionic cyclic form, while in the absence of the barrel the same DASA exist in cyclic zwitterionic form in aqueous medium. The hydrophobic interaction between the cavity and the open form of DASA molecules benefits reaching an out-of-equilibrium or reverse equilibrium state in aqueous medium. The presence of excess MV could even drive the conversion of the stable cyclic form to the open form in aqueous medium. The host-guest complex is stable upon irradiating with green light. To the best of our knowledge, this is the first successful attempt to stabilize the open form of DASA molecules in aqueous medium and the first report on the fate of DASA in a confined space discrete molecular architecture. Furthermore, the molecular vessel has been utilized for catalytic Michael addition reactions of a series of nitrostyrene derivatives with 1,3-indandione in aqueous medium.

中文翻译：

供体-受体 Stenhouse 加合物 (DASA) 在水溶性 PdII8 分子容器的密闭空间中的异常行为

供体-受体 Stenhouse 加合物 (DASA) 是最近发现的新一代光致变色化合物。DASA 通常以开放形式（蓝色/紫色）存在，并且在甲苯/二恶烷中的绿光存在下容易可逆地转化为环状（浅黄色/无色）两性离子形式。在水性介质中，开放形式不稳定并且不可逆地转化为环状两性离子形式。我们在这里报告了一种新的自组装 Pd8 分子容器 (MV)，即使在水性介质中，它也可以稳定和存储 DASA 的开放形式。90° 受体顺式-(tmeda)Pd(NO3)2 (M) [tmeda = N, N, N', N'-四甲基乙烷-1,2-二胺] 与对称四咪唑供体 (L, 3, 3',5,5'-四（1 H-咪唑-1-基）-1,1'-联苯）以 2:1 的摩尔比产生水溶性 [8+4] 自组装 M8L4 分子桶（MV）。该桶 (MV) 被发现是一种潜在的分子容器，可以在更稳定的两性离子环状形式上储存和稳定水性介质中 DASA 的开放形式，而在没有桶的情况下，相同的 DASA 以环状两性离子形式存在于水性介质中中等的。空腔和 DASA 分子的开放形式之间的疏水相互作用有利于在水性介质中达到不平衡或反向平衡状态。过量 MV 的存在甚至可以推动稳定的环状形式在水性介质中转化为开放形式。主客体复合物在绿光照射下是稳定的。据我们所知，这是第一次成功地尝试稳定水介质中 DASA 分子的开放形式，也是第一次报告 DASA 在密闭空间离散分子结构中的命运。

更新日期：2019-05-03

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