新型杯呋喃大环的合成、结构及其与酸相互作用的研究

Calixarene derivatives are widely used in the fields of supramolecular chemistry coordination chemistry self-assembly chemistry, optoelectronic materials, and so on. The extensive development of calixarene studies has fostered growing interest in exploring the chemistry of heterocalixarenes, particularly while the aryl units of calixarenes are replaced by heterocycles. Calixfurans, also known as tetraoxaporphyrinogens, represent a significant class of heterocalixarenes. Here, we present a novel class of calixfuran macrocycles and study their interactions with acid compounds. Under catalysis by sulfuric acid, furan and tetrahydro-2H-pyran-4-one were condensed to obtain calix[4]furan macrocyclic compound C4TP and calix[6]furan macrocyclic compound C6TP. The macrocycles were characterized by ¹H nuclear magnetic resonance (¹H NMR), ¹³C nuclear magnetic resonance (¹³C NMR), and mass spectrometry, specifically, the structure of C4TP and C6TP were determined by single-crystal X-ray diffraction analysis. The crystal of C4TP was cuboidal, colorless with smooth surface, good light transmittance, and triclinic system, space group name was P-1. According to the single crystal structure, the molecular skeleton showed a tetragonal cup structure with mirror symmetry. The four furan rings were enclosed like four walls, and tetrahydropyranes were located at the four corners through spiral-conjugate interactions. It was found that the solvents of macrocycle C4TP could change color after interacting with acid compounds. The interactions between the macrocycle host C4TP and a series of acid guests were systematically studied by ultraviolet-visible absorption spectroscopy. The results indicated that the solvents of macrocycle C4TP and different acids presented new absorption bands in the visible light region, exhibiting different colors. Particularly, when macrocycle C4TP was mixed with methanesulfonic acid (MSA), it appeared a wide range absorption over 300～700 nm and displayed green color. Subsequently, we investigated the effects of interaction time and different equivalents of MSA on the ultraviolet-visible absorption spectra. The results figured out that the interaction between the macrocycle C4TP and MSA essentially reached a stable state after 48 h, and achieved a high intensity at a molar ratio of 1∶2000. This study provides a new model and insight into the research of host-guest interactions of calixfuran macrocycles with acid.