N-Substituted diamino-benzoquinone diimines featuring tunable aryl electron-withdrawing functions and vapochromic properties have been developed.

Newly designed aryl-substituted azacalixphyrins are promising contrast agents for photoacoustic imaging upon excitation in the 800–1000 nm NIR range.

Azacalixquinarenes, a new family of macrocycles constituted of diaminobenzoquinone diimine units linked by dinitrobenzene rings are synthesized by selected oxidation of the parent azacalixarenes. Crystallographic analyses of two compounds demonstrated the presence of (uncharged) canonical and zwitterionic quinones within a single structure. The electron-withdrawing nature of the dinitrobenzene moieties can trigger the intramolecular H-transfer that generates zwitterionic-ground state quinones. The nature of the Nsubstituents and the polarity of the solvent have a crucial impact on the equilibrium between the canonical and zwitterionic forms that present distinct optical and electrochemical properties. Thus, within [4]-and [6]-membered macrocycles, poly-zwitterionic structures can be reached, as demonstrated experimentally and theoretically using first-principle approaches. With the aim to combine several of these systems in a single molecule and study the impact on the canonical/zwitterionic equilibrium, we naturally focused our attention on the elaboration of macrocyclic architectures of types 2 or 3 presenting an alternation of quinones and aromatic rings substituted with EWG. We report herein their synthesis from ACA precursors and demonstrate that these macrocycles (2a-c and 3a), named azacalixquinarenes (ACQ), can be seen as "hemi-azacalixphyrins", i.e. an intermediary class of ACA-ACP derivatives featuring an alternation of dinitrosubstituted aromatic rings and diaminobenzoquinone diimine rings. As for model compounds 1a-d, the quinoidal fragments within ACQs can be either stabilized under canonical (uncharged) or zwitterionic forms depending on given parameters (N-substituents, solvent), allowing to reach unprecedented poly-zwitterionic systems. RESULTS AND DISCUSSION Synthesis. The access to the target ACQs 2a-c was envisaged by chemical oxidation of the azacalix[4]arene precursors (Scheme 1). Therefore, the preparation of ACA 7a-c was carried out following a well-established strategy starting from precursors 4a-c, incorporating octylamine or selected aniline moieties, which were reduced under acidic conditions in presence of Sn(II) salts or Fe powder, then substituted by 1,5-difluoro-2,4-dinitrobenzene (DFDNB) to afford the adducts 6a-c. 30, 34 Scheme 1. Synthesis of compounds 1a-d, 2a-c and 3a (quinones only represented under their canonical forms). These intermediates were converted to the corresponding azacalix[4]arene 7a-c using one equivalent of tetraaminobenzenes 4a-c in refluxing acetonitrile. For compound 6d, previously unknown, the reaction was carried out at room temperature and a low concentration of 5d (10-2 M) was necessary to reach a moderate yield (43%, Table S1). Such poor efficiency is presumably imputable to a lack of regioselectivity during the nucleophilic aromatic substitution of the electron-rich adduct 5d on DFDNB. Unfortunately, for the same reason, it was impossible to reach the corresponding azacalix[4]arene 6d using classical conditions. The synthesis of azacalix[6]arenes 8a wa...