A rare and exclusive endoperoxide photoproduct was quantitatively obtained from a thiacalix[4]arene crown-shaped derivative upon irradiation at λ=365 nm; the structure was unambiguously confirmed by ¹H/¹³C NMR spectroscopy and X-ray crystallography. The prerequisites for the formation of the endoperoxide photoproduct have also been discussed. Furthermore, the photochemical reaction rate could be greatly enhanced in the presence of the thiacalix[4]arene platform because it served as a host to capture oxygen.

A convenient route to a new class of pyrene-based [4]helicenes is presented. Wittig reaction of 7-tert-butyl-1,3-dimethyl-5-formylpyrene with benzyltriphenylphosphonium salts in the presence of nBuLi afforded 7-tert-butyl-1,3-dimethyl-5-(phenylethenyl)pyrenes, from which 4,5-naphthalene annulated aromatic [4]helicenes, namely 7-tert-butyl-1,3-dimethyl-13-methoxydibenzo[ij,no]tetraphene and 7-tert-butyl-1,3,12,14-tetramethyldibenzo[ij,no]tetraphene, were obtained by photoinduced intramolecular cyclization. The chemical structures of these [4]helicenes were determined on the basis of their elemental analyses and spectroscopic data. The helicity in the synthesized [4]helicene induced by the presence of the second methyl group in the fjord region is discussed in detail. The photophysical and electrochemical properties of these newly developed [4]helicenes were fully investigated by UV/Vis absorption and photoluminescence spectrphotometry, and cyclic voltammetry (CV), and the crystal structures were determined for two examples.

Heteroditopic hexahomotrioxacalix[3]arene receptors that are capable of binding an anion and a cation simultaneously in a cooperative fashion were synthesized. The structure of one of the triamide derivatives was confirmed by single-crystal X-ray diffraction. The binding of alkali metals at the lower rim, and the binding of anions (chloride, bromide) at the upper rim, has been investigated by using ¹H NMR titration experiments. Alkali metal binding at the lower rim controls the calix cavity. Li⁺-ion binding to the lower rim can improve the binding ability of anions at the upper rim amide moiety by a factor of 15, thus suggesting a strong positive allosteric effect for anion recognition. However, when a Na⁺ cation is bound to the ionophoric site on the lower rim, the calix cavity is changed from a “flattened cone” to a more-upright form, which is favored for intramolecular hydrogen bonding between the neighboring NH and CO groups; this change can block the inclusion of anions onto the amide moiety at the upper rim, which strongly suggests a negative allosteric effect of Na⁺-ion binding, which controls the cooperative recognition system.

A new series of pyrene-based, pure-blue, fluorescent, stable monomers, namely 2,7-di-tert-butyl-4,5,9,10-tetrakis(p-R-phenylethynyl)pyrenes, have been successfully synthesised by Pd/Cu-catalysed Sonogashira coupling in excellent yield. The cruciform-shaped, π-conjugated structures were fully characterised by ¹H/¹³C NMR and IR spectroscopy, mass spectrometry and elemental analysis. As revealed from single-crystal X-ray analysis, there is a herringbone pattern between stacked columns, but the π-π stacking distance of adjacent pyrene units was not especially short at about 5.82 Å due to the introduction of the two bulky tBu groups in the pyrene rings at the 2- and 7-positions. The photophysical properties of these monomers were carefully examined in different organic solvents, and these data strongly indicate their promising application as blue-emitting materials in organic light-emitting diodes (OLEDs).