Effect Of Counter Ions On Self-assembles And CB Molecule Reactor

Cucurbit[n]uril is a series of complexes with barrel-shaped hydrophobic cavity. CB[n] family has many members such as CB[5], CB[6], CB[7] and CB[8]. Because of its special structure, CB[n] was wildly used in many areas including host-guest Chemistry, molecule recognition and biological macromolecules detection. Viologen derivates are one of the most important guests with CB[n], which can be accommodated in the cavity of CB[n] by ion dipole interaction. In addition, viologen derivates have remarkable physical chemistry properties, which make them useful in molecular switch design and DNA photocleavage.In viologen derivatives, counter ions are needed to keep the molecule neutral. Different counter ions can be employed to design cross-linked polyviologen film to recognize halide ions. Counter ions can also change the physical chemistry properties of self-assemble complexes between viologen derivates and host complexes. We designed a series of viologen derivative BEV with different counter ions including halide ions and organic ions such as PF6-and ClO4-. Our research suggested that the counter ions were located just outside the cavity of CB[8], integrated with including complexes by electrostatic interaction. Different counter ions can change the dimerization constant of self-assembly process. After reduced by rongalite, BEV-2X radical cation can form a stable1:2complex within CB[8].CB[n] can be a reactor to accelerate1,3-dipolar cycloaddition and light polymerization. Electrophilic substitution reaction is very important to aromatic compounds, but there is no report that CB[n] was employed to control electrophilic substitution reaction. We synthesized a complex PhEV composed of phenol and viologen. According to our research, PhEV can assemble with CB[n] in different molecule architecture. CB[6] can assemble with phenol part while CB[7] can assemble with viologen part. When comes to CB[8], phenol part and viologen part can form CT complex to assemble with CB[8]. The density of electron cloud of phenol was different because of different assembly architecture. So when bromine atom substitute the hydrogen atom of phenol, different products such as monosubstituted, double substituted or trisubstituted phenol can be achieved within different size of cavity. This is the first time CB[n] was employed to control electrophilic substitution reaction.