Macrocyclic host molecules with aromatic building blocks: the state of the art and progress

Macrocyclic host molecules play the central role in host-guest chemistry and supramolecular chemistry. The highly structural symmetry of macrocyclic host molecules can meet people's pursuit of aesthetics in molecular design, and generally means a balance of design, synthesis, properties and applications. For macrocyclic host molecules with highly symmetrical structures, building blocks, which could be described as repeat units as well, are the most fundamental elements for molecular design. The structural features and recognition ability of macrocyclic host molecules are determined by the building blocks and their connection patterns. Using different building blocks, different macrocyclic host molecules could be designed and synthesized. With decades of developments of host-guest chemistry and supramolecular chemistry, diverse macrocyclic host molecules with different building blocks have been designed and synthesized. Aromatic building blocks are a big family among the various building blocks used in constructing macrocyclic host molecules. In this feature article, the recent developments of macrocyclic host molecules with aromatic building blocks were summarized and discussed.

Synthesis, Structures, and Electronic Properties of 2,7-Anthrylene-Based Azacyclophanes Bearing o-, m-, and p-Phenylenediamine Linkers

A series of novel azacyclophanes consisting of 2,7-anthrylene and phenylene units were designed and synthesized by the Buchwald-Hartwig coupling reaction to investigate their unique electronic properties in multiple oxidized states. Cyclic voltammetry showed that the p-phenylene derivative exhibited three reversible oxidation waves, whereas the o- and m-phenylene derivatives showed two quasi-reversible oxidation waves due to the complicated intramolecular interaction between the oxidized units and neutral units. Moreover, the absorption spectra of the p-phenylene derivative in different oxidation states showed absorption bands at 865 and 1025 nm, which were attributed to intramolecular charge-transfer interactions. The photophysical and electrochemical properties of the p-phenylene analog were also compared with those of the o- and m-phenylene derivatives based on theoretical calculations for further evaluation of the intramolecular electronic interactions.

Electron-poor arylenediimides

This review article highlights the emergence of eclectic molecular design principles to realize remarkably strong electron deficient arylenediimide molecules, aspects of their stability and associated applications.

Electronic structure of tetraaza[1.1.1.1]o,p,o,p-cyclophane and its oxidized states

The smallest macrocyclic oligoarylamine bearing the alternantortho–para-linkage exhibits the unique structural and electronic features.

Polymers for electronics and spintronics

This critical review is devoted to semiconducting and high spin polymers which are of great scientific interest in view of further development of the organic electronics and the emerging organic spintronic fields. Diversified synthetic strategies are discussed in detail leading to high molecular mass compounds showing appropriate redox (ionization potential (IP), electron affinity (EA)), electronic (charge carrier mobility, conductivity), optoelectronic (electroluminescence, photoconductivity) and magnetic (magnetization, ferromagnetic spin interactions) properties and used as active components of devices such as n- and p-channel field effect transistors, ambipolar light emitting transistors, light emitting diodes, photovoltaic cells, photodiodes, magnetic photoswitches, etc. Solution processing procedures developed with the goal of depositing highly ordered and oriented films of these polymers are also described. This is completed by the description of principal methods that are used for characterizing these macromolecular compounds both in solution and in the solid state. These involve various spectroscopic methods (UV-vis-NIR, UPS, pulse EPR), electrochemistry and spectroelectrochemistry, magnetic measurements (SQUID), and structural and morphological investigations (X-ray diffraction, STM, AFM). Finally, four classes of polymers are discussed in detail with special emphasis on the results obtained in the past three years: (i) high IP, (ii) high |EA|, (iii) low band gap and (iv) high spin ones.

Functionalization of the methylene bridges of the calix[6]arene scaffold

The bromine atoms of the hexabromo calixarene derivative 3 were replaced by other groups under S(N)1 conditions, allowing the facile synthesis of calix[6]arene derivatives incorporating identical functionalities at all bridges. Heating at reflux a mixture of 3 and the appropriate alcohol incorporated primary and secondary alkoxy substituents. Hydride abstraction was observed when the reaction with EtOH and i-PrOH was conducted in hexafluoroisopropanol (HFIP). Solvolysis of 3 in TFE in the presence of strong nucleophiles (such as N3(-) and aniline) afforded the corresponding hexaazido and hexaanilino derivatives. Hydroxyl groups were incorporated into the calix[6]arene scaffold via acetolysis of 3, followed by LiAlH4 reduction of the hexaacetate derivative obtained. Friedel-Crafts alkylations in the absence of Lewis acids were conducted by heating at reflux a mixture of 3, HFIP, and a substituted benzene derivative (e.g, m-xylene, p-methyl anisole, mesitylene). The calix[6]arene bridges were alkylated by heating at reflux a mixture of 3 and 2,4-pentanedione in TFE or HFIP. In all cases the reaction proceeded with high diastereoselectivity, and the major isomer isolated was assigned to the rc5 (i.e., all-cis) form. NMR spectroscopy indicates that the conformation adopted by the macrocycle possesses 3-fold symmetry (a "pinched cone") that is rigid in the laboratory time scale in the mesityl-substituted derivative.