Synthesis Of Cucurbiturils And Its Supramolecular Chemistry Incorporating Metal Cation Complexes

Cucurbit[n]urils is a kind of special pumpkin-shaped macrocyclic compounds of glycoluril, whose structure forms a rigid hollow cavitand with two highly polar carbonyl openings, and thus has primarily been used as a synthetic receptor for selectively binding linear organic substrates. However, the chemical behavior of its hydrophobic outer wall has nearly been investigated and utilized. In view of its unique pumpkin molecular shape which may be potential for inducing novel stereo-specificity in structure construction, It can recognize guests including metal ions and organic molecules via supramolecular interactions because of its unique cavity structure. These capabilities consequently make them attractive as both receptors for molecular recognition and building blocks for the construction of nano-scaled supramolecular systems. It has great application potentiality in the molecular recognition, molecular self-assembly, molecular catalysis, pollution water treatment, mimic enzyme and drug pilot carrier. So, the new kind of host is arousing more and more researchers'considerable interests.In this paper, according to synthesized the CBn homologous compounds and characterized them by IR, ¹H-NMR, Elemental Analysis, we discussed their differences on structures and properties. On this basis, we synthesized two novel hybrid supramolecule which are [Cu(HQS)₂][Na₂(CB₆)(H₂O)₈]·6H₂O and [Cu(HQS)2][K2(CB6)(H2O)8]·9H2O, characterized their structures by XRD and compared.The X-ray analyses showed that complex 1 was crystallized in Triclinic, PÄ«space group, a=11.843(2) A, b=12.381(3) A, c=15.328(3) A,α=110.884(4)°,β=112.428(4)°,γ=91.520(3)°, V=1906.3(7) A³, Z=1, F(000)=935, D_calc=1.572 g/cm³,μ=0.459 mm^-1, R₁[I>2σ(I)]=0.0489 and wR₂ (all data)=0.1612; Complex 2 was crystallized in Triclinic, PÄ«space group, a=11.8200(11) A, b=13.0280(11) A, c=14.713(4) A,α=114.800(3)°,β=110.530(3)°,γ=91.800(3)°, V=1883.2(6) A³, Z=1, F(000)=981, D_calc=1.668g/cm³,μ=0.570 mm^-1, R₁[I>2σ(I)]=0.0645 and wR₂ (all data) = 0.1281.According to the crystal structures of complex 1 with complex 2, we found there are some differences between them. The results showed that alkali metal ions can be used as one of the effective controlling factors for this kind of self-assembly.On the other hand, we try to use this feature who has a hydrophobic cavity to research the mixed system. We research its properties by UV-Vis spectrum. To compare with others, we found the CB8 which has a lager cavity affectes the [Cu(en)₂]²⁺ complex cation system significantly. It is possibly caused by the interaction between the CB8 and the ligands and we supposed that [Cu(en)₂]²⁺ complex cation is in the cavity.The present results may be significant for the supramolecular application of the macrocyclic CBn family.