Tetranitro- and tetraamino-dibenzo[18]crown-6-ether derivatives: complexes for alkali metal ions, redox potentials, crystal structures, molecular sorption, and proton conducting behaviours
Tetranitro- and tetraamino-dibenzo[18]crown-6-ether derivatives: complexes for alkali metal ions, redox potentials, crystal structures, molecular sorption, and proton conducting behaviours
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DOI：
10.1039/d2ce00582d
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发表时间：
2022-06-29
期刊：
影响因子：
3.1
通讯作者：
Akutagawa，Tomoyuki
中科院分区：
文献类型：
--
作者：
Shimizu，Yuta;Takeda，Takashi;Akutagawa，Tomoyuki
四硝基二苯并[18]冠-6（1）和四氨基二苯并[18]冠-6（2）分别是离子识别电子受体和电子给体分子。1的电子接受能力低于邻二硝基苯，而2的给电子能力超过典型的给电子体四硫富瓦烯。在酸性条件下，通过在两个-NH 2位点处的双质子化，2的氧化电位急剧降低。热退火的1在200 K和77 K分别对CO2和N2表现出开门式的吸附-脱附行为。1的中心空腔可以结合碱金属离子（M）形成M（1）络合物，M = Na+、K+、Rb+和Cs+;这些络合物结晶成单体（M = Na+和K+）、二聚体（M = Rb+）和一维聚合物（M = Cs+），形成[M（1）I]·nCH 3CN单晶。在M+位点处的多个M+ → O2 N-轴向配位在固体中产生二聚体和聚合物网络。在Na+和K+存在下，在稀H2SO 4溶液中，通过2的结晶得到[Na（2）（H2SO 4）3]·nH 2 O和[K（2）（H2SO 4）3]·nH 2 O的单晶。单晶形成了一个一维排列的离子通道<$[（Na）0.25（2）]<$H2O <$[（H3 O）0.25（2）]<$H2O <$，HSO 4-和H2SO 4的混合质子化态借助额外的H2O分子占据离子通道周围形成了O-H <$O氢键网络。相反，HSO 4 −的两个氧原子轴向配位到K（2）络合物上，使它们彼此分离，HSO 4 −和H2O占据[K（2）（H2SO 4）3]。这两种水合晶体在310 K时的质子电导率（σH+）为1.5 μS cm−1，而脱水晶体中的σH+值消失;此外，在德拜型介电弛豫中观察到极性HSO 4 −的运动自由。
Tetranitro-dibenzo[18]crown-6 (1) and tetraamino-dibenzo[18]crown-6 (2) are ion-recognition electron acceptor and electron donor molecules, respectively. The electron-accepting ability of 1 is lower than that of o-dinitorobenzene, whereas the electron-donating ability of 2 exceeds that of tetrathiafulvalene, a typical electron donor. The oxidation potential of 2 is drastically reduced by di-protonation at the two –NH2 sites under acidic conditions. Thermally annealed 1 exhibits gate-opened gas adsorption–desorption behaviors for CO2 at 200 K and N2 at 77 K. The central cavity of 1 can bind alkali metal ions (M) to form M(1) complexes for M = Na+, K+, Rb+, and Cs+; these crystallize into monomers (M = Na+ and K+), dimers (M = Rb+), and one-dimensional polymers (M = Cs+) in single crystals of [M(1)I]·nCH3CN. Multiple M+⋯O2N– axial coordination at the M+ site generates dimer and polymer networks in solids. Single crystals of [Na(2)(H2SO4)3]·nH2O and [K(2)(H2SO4)3]·nH2O were obtained by crystallization of 2 in the presence of Na+ and K+, respectively, in dilute H2SO4. The single crystals formed an ionic channel in the one-dimensional array of ⋯[(Na)0.25(2)]⋯H2O⋯[(H3O)0.25(2)]⋯H2O⋯, and the mixed protonated state of HSO4− and H2SO4 formed an O–H⋯O hydrogen-bonding network with the aid of additional H2O molecule occupation around the ionic channels. In contrast, the two oxygen atoms of HSO4− were axially coordinated to the K(2) complex, which isolated them from each other, and HSO4− and H2O occupied [K(2)(H2SO4)3]. These two hydrated crystals showed a proton conductivity (σH+) of ∼5 μS cm−1 at 310 K, while in the dehydrated crystals the σH+ values disappeared; furthermore, the motional freedom of the polar HSO4− was observed in the Debye-type dielectric relaxations.