Dipyridinocalixcrown/diiodoperfluorocarbon binary host systems for CsI: structural studies and fluorous phase extraction of caesium

A mixture of partial cone 2,4-bis[(2-pyridylmethyl)oxy]-(1,3)-p-tert-butylcalix[4]crown-6, hexadecafluoro-1,8-diiodooctane and CsI in EtOH produces a crystalline ‘supramolecular salt’. In the solid state the caesium ion of the ‘supercation’ is encapsulated inside the cavity created by the crown ether loop, the picolyl and the inverted phenyl moieties, while the two iodide ions of the ‘superanion’ form a discrete five-component aggregate held together by co-existing hydrogen and halogen bonds. Similar calix/CsI/iodofluorocarbon adducts are shown to exist also in solution. In a prototypical study, a combination of this calixcrown and liquid octafluoro-1,4-diiodobutane acts as an effective ‘binary host’ system for the selective extraction of CsI from aqueous to fluorous phase.     

A Structural Study of Tautomerism and Hydrogen-Bonding in Supramolecular Assemblies

The synthesis and X-ray structures of four new crystalline materials incorporating ’dimers’ assembled from two different units possessing complementary hydrogen bonding motifs are reported; namely, phthalimide and 3-iminoisoindolinone or 2-guanidinobenzimidazole (or selected methylated derivatives) and 2-guanidinobenzoxazole. The bonding within each dimer involves a triplet of hydrogen bonds. The extended supramolecular structures are compared with each other as well as with two related structures described previously. The effect of using complementary DAD/ADA motifs that are not symmetrical on the respective supramolecular structures is also examined as is the prospect of incorporating different tautomeric components into the supramolecular structures. The presence of a very short, proton-transferred hydrogen bond within the respective triplets is also discussed.     

卤键在超分子化学中的应用进展

卤键是指作用在卤原子(路易斯酸)和具有孤对电子的原子或π电子体系(路易斯碱)之间的新型弱相互作用,其在超分子多维自组装和分子识别(如超分子催化、超分子选择拆分、超分子传感)等领域有着广泛的应用。本文介绍了卤键的类别、特性、功能及在超分子化学结构与功能领域中的应用。     

Supramolecular Assemblies of Phosphorylated Cavitands

The recent results in the chemistry of cavitands have proved that they are very efficient molecular receptors and potential precursors of molecular devices. In this context, we have investigated the synthesis and binding properties of phosphorylated cavitands. The stereoselective synthesis and the structural studies of the new compounds showed that these bowl-shaped molecules possess a well defined aromatic cavity surrounded by four phosphoryl groups (P=O or P=S). They are very efficient ligands for metal and organic cations. They are able to encapsulate cationic species by cooperative effect of the preorganized aromatic cavity and the four phosphorylated groups. Moreover, the upper and lower rim functionalitics can lead to the formation of molecular capsules and supramolecular assemblies whose properties and structures have been investigated by X-ray diffraction and NMR studies in solution.     

环糊精超分子组装体的研究进展

环糊精是由若干个D-吡喃葡萄糖单元通过α-1,4-糖苷键连接而成的环状低聚糖,具有一个亲水性的外表面和一个疏水性的空腔。利用主客体相互作用,环糊精及其衍生物能够选择性地与大小匹配的疏水性客体分子形成各种超分子包合物。本文概述了环糊精的结构与性质,并介绍了近年来国内外以环糊精为基础的纳米粒子、水凝胶等超分子组装体的设计原理、作用机制、刺激响应及应用特点,并对环糊精超分子组装体的前景进行了展望。     

Metal-mediated Discrete Supramolecular Assemblies of Porphyrins

There is substantial recent interest worldwide in the construction of multiporphyrin assemblies which can either mimic naturally occurring multichromophore aggregates, such as the photosynthetic reaction center and the light harvesting complex of purple bacteria, or which can be used as electron- and/or energy-transfer molecular devices for advanced technological tasks. The metal-mediated self-assembly approach, which exploits the formation of coordination bonds between peripheral basic site(s) on the porphyrins and metal centers, has recently allowed the design and preparation of sophisticated supramolecular architectures whose complexity and function begin to approach the properties of naturally occurring systems. Within this framework, meso -pyridyl/phenyl porphyrins (PyPs), or strictly related chromophores, can provide geometrically well-defined connections to as many as four metal centers by coordination of the pyridyl groups. Several discrete assemblies of various nuclearities, in which the pyridylporphyrins are linkers binding metalloporphyrins and/or coordination compounds, have been constructed in recent years. Our contribution to this field is reviewed, with the aim of providing insight into the design of new, more elaborated architectures of higher order.     

Adaptive Supramolecular Networks: Emergent Sensing from Complex Systems

Molecular differentiation by supramolecular sensors is typically achieved through sensor arrays, relying on the pattern recognition responses of large panels of isolated sensing elements. Here we report a new one-pot systems chemistry approach to differential sensing in biological solutions. We constructed an adaptive network of three cross-assembling sensor elements with diverse analyte-binding and photophysical properties. This robust sensing approach exploits complex interconnected sensor-sensor and sensor-analyte equilibria, producing emergent supramolecular and photophysical responses unique to each analyte. We characterize the basic mechanisms by which an adaptive network responds to analytes. The inherently data-rich responses of an adaptive network discriminate among very closely related proteins and protein mixtures without relying on designed protein recognition elements. We show that a single adaptive sensing solution provides better analyte discrimination using fewer response observations than a sensor array built from the same components. We also show the network's ability to adapt and respond to changing biological solutions over time.     

Stabilizing Liquids Using Interfacial Supramolecular Assemblies

Stabilizing liquids based on supramolecular assembly (non-covalent intermolecular interactions) has attracted significant interest, due to the increasing demand for soft, liquid-based devices where the shape of the liquid is far from the equilibrium spherical shape. The components comprising these interfacial assemblies must have sufficient binding energies to the interface to prevent their ejection from the interface when the assemblies are compressed. Here, we highlight recent advances in structuring liquids based on non-covalent intermolecular interactions. We describe some of the progress made that reveals structure–property relationships. In addition to treating advances, we discuss some of the limitations and provide a perspective on future directions to inspire further studies on structured liquids based on supramolecular assembly.     

Organic‐Inorganic Hybrid Supramolecular Assemblies Based on Isomers [HxAs2Mo6O26](6–x)– Clusters

The arsenomolybdates [H₂As₂Mo₆O₂₆(H₂O)] · (H₂biyb)₂ · 2H₂O ( 1 ) and [H₃As₂Mo₆O₂₆] · (H₃pt)₂ ( 2 ) [biyb = 1,4‐bis(imidazol‐1‐ylmethyl)benzene, pt = 4′‐(3′′‐pyridyl)‐2,3′:6′3′′‐terpyridine] were synthesized via hydrothermal method. The structures of the compounds were characterized by single‐crystal X‐ray diffraction analyses, elemental analyses, IR spectroscopy, and TG analysis. Compounds 1 and 2 exhibit two isomeric forms of [H_xAs₂Mo₆O₂₆]^(6–x)–. The structure of 1 is constructed from the B‐type [H₂As₂Mo₆O₂₆(H₂O)]^4– polyanions and free biyb ligands via weak interactions to form 3D supramolecular framework with a {3 · 4 · 5³ · 6}{3 · 4³ · 5²}{3 · 5 · 6}²{3 · 5²}² topology structure. In compound 2 , the A‐type [H₃As₂Mo₆O₂₆]^3– clusters are surrounded by pt ligands through hydrogen bond interactions forming 3D supramolecular framework with a {4³ · 6³}²{4⁶ · 6⁶ · 8³} topology structure. The electrochemical behaviors, electrocatalytic and photocatalytic activities of 1 and 2 are detected.     

Supramolecular AA/BB-type oligomer formation from a heterotetratopic bis-calix[5]arene monomer and octanediyldiammonium dichloride

A novel bis-calix[5]arene (1) with divergent cavities was prepared in four steps starting from p-methylcalix[5]arene. This molecule is composed of two calix[5]-bis-crown-3 units held together, via their narrow rims, by a N,N″-1,4-phenylene-bis[N′-(2-ethenyloxyethyl)]diureido bridging moiety. Owing to the anion-binding ability of the ureido moieties embedded in its framework, bis-calix[5]arene 1 acts as a heterotetratopic monomer and, in the presence of 1,8-octanediyldiammonium dichloride, self-assembles into AA/BB-type polycapsular oligomers. Extensive ¹H NMR investigations have demonstrated that the nature and stoichiometry of these supramolecular oligomers are strongly dependent on the concentration and the ratio of the two monomers.     

典型锕系超分子组装体的构筑原理及研究进展

锕系超分子化学是锕系元素化学的重要研究领域,可以为乏燃料后处理的配位化学基础研究提供重要信息,并为探索锕系功能材料在发光、传感、催化和分离等方面的功能应用提供关键材料体系。本文介绍了基于锕系金属离子的金属-有机超分子组装体这一新兴领域的最新研究进展。从锕系超分子组装体的构筑原理出发并结合笔者自身研究情况,对基于主客体准轮烷配体的锕系-轮烷配位聚合物、具有闭合结构的锕系配位组装体和基于超分子相互作用的锕系超分子聚合物这三类典型的锕系超分子组装体的研究进展进行了梳理和总结阐述。期望为未来新型锕系超分子组装体的设计合成提供参考,促进相关领域的进步和发展。     

Polymeric Carbon Nitride with Chirality Inherited from Supramolecular Assemblies

The facile synthesis of chiral materials is of paramount importance for various applications. Supramolecular preorganization of monomers for thermal polymerization has been proven as an effective tool to synthesize carbon and carbon nitride-based (CN) materials with ordered morphology and controlled properties. However, the transfer of an intrinsic chemical property, such as chirality from supramolecular assemblies to the final material after thermal condensation, was not shown. Here, we report the large-scale synthesis of chiral CN materials capable of enantioselective recognition. To achieve this, we designed supramolecular assemblies with a chiral center that remains intact at elevated temperatures. The optimized chiral CN demonstrates an enantiomeric preference of ca. 14 %; CN electrodes were also prepared and show stereoselective interactions with enantiomeric probes in electrochemical measurements. By adding chirality to the properties transferrable from monomers to the final product of a thermal polymerization, this study confirms the potential of using supramolecular precursors to produce carbon and CN materials and electrodes with designed chemical properties.     

Macrocycle-Based Crystalline Supramolecular Assemblies Built with Intermolecular Charge-Transfer Interactions

Synthetic macrocycles have served as principal tools for supramolecular chemistry, have greatly extended the scope of organic charge transfer (CT) complexes, and have proved to be of great practical value in the solid state during the past few years. In this Minireview, we summarize the research progress on the macrocycle-based crystalline supramolecular assemblies primarily driven by intermolecular CT interactions (a.k.a. macrocycle-based crystalline CT assemblies, MCCAs for short), which are classified by their donor–acceptor (D-A) constituent elements, including simplex macrocyclic hosts, heterogeneous macrocyclic hosts, and host–guest D-A pairs. Particular attention will be focused on their diverse functions and applications, as well as the underlying CT mechanisms from the perspective of crystal engineering. Finally, the remaining challenges and prospects are outlined.     

Self-assembly of nitroxide radicals via halogen bonding—directional NO?I interactions

Novel supramolecular self-assemblies of nitroxide free radicals via noncovalent halogen bonding are synthesised. A directional NO?I interaction is observed in a one-dimensional coordination polymer consisting of alternating electron donor and acceptor molecules.     

Mn4-硫杂杯[4]芳烃单元的溶剂导向超分子组装

以去叔丁基硫杂杯[4]芳烃与Mn(II)为研究对象,通过改变体系溶剂分别得到了两个四核化合物Mn4(T4A)2 (1)和Mn4(T4A)2(DMF)2(2) (T4A = thiacalix[4]arene)。当反应溶剂为氯仿(CHCl3)和甲醇的混合溶剂时,形成的是以四核锰为结构单元的二维“笼目”(Kagomé)状超分子化合物1,而当反应溶剂为N,N-二甲基甲酰胺(DMF)和甲醇的混合溶剂时,得到的是格子状二维超分子互穿的三维结构化合物2。化合物1具有很大的溶剂占有空隙,是一个潜在的多孔材料,而化合物2是一个紧密堆积的拓展结构。     

Supramolecular fluoride and chloride anions

The Cambridge Structural Database has been searched for supramolecular anions of the form H_nX_n + 1⁻ where X is fluorine (n = 1 to 6) and chlorine (n = 1 to 5); no credible evidence was found for comparable bromine or iodine species. Several structural isomers have been identified, and an experimental measure has been developed which seems to distinguish between two-centre and three-centre bonded species. There are also examples of suprafluoride and suprachloride anions as ligands in organometallic complexes. Most of these anions have not been previously described.     

Perfluorocarbon-hydrocarbons self-assembly: halogen bonding mediated intermolecular recognition

Halogen bonding is discussed as an interaction that is capable of overcoming the reluctance shown by fluorinated compounds towards interactions with hydrocarbons. This non-covalent interaction is sufficiently strong to enact formation of supramolecular architectures where perfluorocarbons, hydrocarbons, and inorganic salts are self-assembled. Examples are discussed which exemplify the consistency and versatility of this interaction in affording numerous and structurally different hybrid materials. The importance of fluorine in determining the overall packing of the formed architectures is also highlighted.     

Synthesis of amine, halide, and pyridinium terminated 2-alkyl-p-tert-butylcalix[4]arenes

The synthesis of calix[4]arenes with functional groups tethered to a single methylene bridge has been explored. Mono-lithiated calix[4]arenes react with 1,ω-bromochloroalkanes to give 2-(ω-chloroalkyl)-calix[4]arenes, which function as key intermediates in the synthesis of a variety of tether-functionalized calix[4]arenes. Subsequent reactivity of these chloroalkyl species has allowed for successful synthesis of 2-(ω-iodoalkyl)-calix[4]arenes, 2-(ω-pyridiniumalkyl)-calix[4]arenes, and 2-(ω-aminoalkyl)-calix[4]arenes. This latter group of amine-terminated calix[4]arenes are especially significant as they may serve as useful entries to a wide range of subsequent chemistry, including metal coordination or attachment to a solid support. Both alkyl and aryl amines have been incorporated at the end of the tether, and a 2,6-diisopropylaniline derivative has been analyzed by X-ray diffraction.