Synthesis And Properties Of Pillararenes-based Pseudo [1]Rotaxane And Their [1]Rotaxane

As a new class of supramolecular macrocyclic hosts after crown ethers, cyclodextrins, calixarenes, and cucurbiturils, pillar[n]arenes are useful and interesting macrocyclic compounds that present repeating units are connected by methylene bridges at the para positions forming a pillar architecture, which were first reported by T. Ogoshi et al. in 2008. Through a variety of functionalizations to develop many pillararene derivatives that exhibit very interesting host-guest properties has gradually become the focus of supermolecular chemistry, which widely used to fabrication of (pseudo)rotaxanes, poly(pseudo)rotaxanes, dimers or polymers. In this paper, we describe strategies for the synthesis and functionalization of pillararenes, we also discuss their host-guest properties.1. On the basis of our previous work on calixarenes and calixpyrrole, we designed and synthesized a series of mono-amide-functionalized pillar[5]arenes with different lengths of N-ω-aminoalkyl groups as the side chain on the rim, which all formed pseudo[1]rotaxanes in the crystal state. And these pseudo[1]rotaxanes could be transformed into [1]rotaxanes or open forms in the crystal state. In addition, they were also studied in solution by 1-H NMR spectroscopy. We cultivated 12 crystal compounds, and all compounds were characterized by NMR, IR, ESI-MS, melting, etc.2. A series of new pillar[5]arene derivatives containing thiourea moieties were conveniently synthesized and characterized. Determination of single crystal structures indicated that the chain unit of thiourea moieties inserted to the cavity of pillar[5]arene to form corresponding pseudo[1]rotaxane in solid state. However, different structures were invented in some solutions, on which many factors depended. Furthermore, NMR titration was investigated to research their recognition of anions in solution. We cultivated 3 crystal compounds, and all compounds were characterized by NMR, IR, ESI-MS, melting, etc.3. A series of copillar[5]arenes mono-schiff bases were conveniently synthesized by the condesation reaction of pillar[5]arene mono-oxyacetohydrazide with substituted salicylaldehydes, isatins, acetoacetone and terephthalaldehyde in refluxing ethanol. Determination of single crystal structures indicated that the chain unit of mono-schiff base exists in the outside of the cavity of copillar[5]arene, which is more convenient to metal ion recognition. We found that copillar[5]arenes mono-schiff bases have a strong ability to identify metal Zn2+, Cu2+, Ni2+ in recognition experiments. We cultivated 5 crystal ligand compounds and 2 crystal metal-ligand compounds, and all compounds were characterized by NMR, IR, ESI-MS, melting, etc.