SELF-ASSEMBLING TETRATHIAFULVALENE-BASED ROTAXANES AND CATENANES

A general stepwise approach is described for the preparation of tetrat hiafulvalene (TTF)-based linear and mono- and dimacrocyclic compounds incorporating one of two 1,4-dioxyphenylene, 9,10-dioxyanthrylene or 1 ,5- or 2,6-dioxynaphthylene units from readily available starting mate rials. By utilizing, the pi-pi stacking interactions of the TTF unit w ith the dipyridinium dication of 1,1'-[1,4-phenylenebis (methylene)] b is-4,4'-bipyridinium bis(hexafluorophosphate), a rotaxane and two [2]c atenanes were synthesized starting from the linear monomacrocyclic com pounds, respectively. From the dioxypheylene-based di-macrocycle, thre e [3]pseudocatenanes (trans, cis, and a mixture of cis/trans isomers) were obtained with the trails compound as the major product. From the dioxyanthrylene dimacrocycle, only the trans-[3]pseudocatenane was obt ained. Catenane products were formed quantitatively from the 1.5-dioxy naphthylene dimacrocycle ina template-directed reaction, affording a t rans-[3]pseudo-catenane together with a [4]pseudocatenane (mixture of cis/trans isomers). From the 2.6-dioxynaphthylene dimacrocycle, a cis- [3]pseudocatenane was obtained as the major product and a trans-[3]pse udocatenane as the minor one. For the [3]pseudocatenanes (i.e., both t he eis and trans catenanes). in which the TTF units were clamped by th e tetracationic macrocycle, isomerizations were completely prevented e ven in the presence of trifluoroacetic acid. All new rotaxanes and cat enanes were characterized by electrospray mass spectrometry, and the c is- and trans-[3]pseudocatenanes were additionally investigated by H-1 NMR spectroscopy. The electrochemical and spectral properties of the rotaxane and the catenanes are reported. Catenane formation increases the redox potentials of the TTF unit. The results demonstrate the vers atility of TTF as a building block in the construction of supramolecul ar structures.