Synthesis And Molecular Recognition Of Bisphosphorylpillar[5]Arene

Supramolecular chemistry is defined as “chemistry beyond the molecule” by Nobel Price laureate Jean-Marie Lehn and it’s about the association of two or more chemical components by the non-covalent, intermolecular forces. Supramolecular chemistry has been developed into three areas: the area of the molecular recognition, the area of the self-processes and constitutional dynamic chemistry. Macrocycles are important building blocks in supramolecular structure, are being developed, diversified and functionalized. As the fifth main macrocyclic host group, with the rigid construction and easy modification, pillararene has attract a lot of attention, especially the molecular recognition and self-assembly of water-soluble pillararene. In this dissertation, we focus on the synthesis and molecular recognition of bisphosphorylpillar[5]arene.To obtain the precursor of difunctioned pillar[5]arene, we used CH2Cl2 as the solvent and an aqueous solution as an oxidizing agent to constructed a heterogeneous system, which produced the chemicalkinetizs result more easier than using other synthesis methodology. we promoted the yield of pillar[4]arene[1]quinone from 30% to 65%, and generated the o-position pillar[3]arene[2]quinone and pillar[2]arene[3]quinone. This synthesis methodology has enriched the pattern of the synthesis of pillar[4]arene[1]quinone and may save a lot of time and energy for the difunctionalization of pillar[5]arene.To study the main driven force of the host-guest complexation, we synthesized the bisphosphorylpillar[5]arene H1 and H2, and study the complexation behavior between H1,H2 and hexamethylene diamine G1 and its hydrochloride salt G2 by the 1H NMR titration experiment The interaction between the phosphate moiety of H2 and the ammonium moiety of G2, which can be identified as a hydrogen bond, plays a key role in the host–guest complexation and accounts for the observed strong binding between H1-G1 and between H2-G2. Moreover, the binding constant of H1–G1 are the same or at least in the same error range as that of H2–G2, suggesting that the host–guest complexation in these two systems might be mainly driven by the same force. Indeed, the proton transfer from the phosphoric acid moiety of H1 to the amine moiety of G1, followed by the formation of hydrogen bond between the newly formed phosphate and ammonium moieties, is expected during the complexation between H1 and G1.The host-guest complex behavior between H2 and biquaternary ammonium salt with different chain length has been studied with 1H NMR and ITC, and we concluded that with the match length, the host-guest complexation is more stable and with a higher complexing constant.The complexations of H2 with alkyl halides were studied in water. Remarkably, the addition of alkyl dihalides(X(CH2)nX; X = Cl, Br or I; n = 4 or 6) into H2 aqueous solutions led to a prompt precipitation of white solids. The solids were further confirmed by 1H NMR spectra as H2–alkyl dihalide complexes. The interaction between the substituting groups of the guest and the host plays a key role for the H2–guest complexation in aqueous solutions. Regarding to the H2–alkyl dihalides system, this driving force could be identified as a C–X???O–P interaction, i.e. a halogen bond. As we know, H2 are solubilized in water due to the formation of the hydrogen bonds between water and the phosphate group of H2. The precipitation of H2–alkyl dihalides complex can then be explained by the replacement of the H2–water hydrogen bonds with the H2–alkyl dihalide halogen bonds.