Improved Pseudorotaxane and Catenane Formation from a Derivative of Bis(m-phenylene)-32-crown-10

2,2'-Dihydroxy-bis(m-phenylene)-32-crown-10 (2,2'-dihydroxy-BMP32C10, 1a) was synthesized and used to prepare the [2]catenane 4 in an unexpected yield of 68%, three times the corresponding value for the case in which BMP32C10 (1b) was used and close to the corresponding value for the case in which bis(p-phenylene)-34-crown-10 was used. This indicated that 1a and paraquat derivatives formed pseudorotaxanes rather than the previously reported taco complexes between BMP32C10 and paraquat derivatives. Another unique feature of 1a in relation to other previously reported BMP32C10 derivatives was that its binding to paraquat derivatives in solution could be switched off and back on by addition of K+ and then dibenzo-18-crown-6. In the solid state, a 2: 1 [3]pseudorotaxane of 1a with a paraquat derivative was formed.