[3]rotaxanes composed of two dibenzo-24-crown-8 ether wheels and an azamacrocyclic complex

Abstract

The first [3]rotaxane based on a tetraazamacrocyclic nickel(ii) complex was synthesized and investigated.

Monosulfonated dibenzo-24-crown-8 and its properties

“…For this purpose, we have used axle 2 (Scheme 2), which contains a tetraazamacrocyclic complex unit of a family that has formerly been utilized for various DB24C8-containing rotaxanes. 14,15,19,25,26,61,62 Contrary to the experiments with neutral DB24C8, the new S DB24C8 wheel poses some synthesis challenges as it seems to decrease the stability of the enamine moiety in tetraazamacrocyclic axles. Nevertheless, in one of the attempts, the reaction of 2 , S DB24C8 − Bu 4 N + and 3,5-bis(trifluoromethyl)phenyl isocyanate resulted in rotaxane 3 (Scheme 2).…”

“…This mechanically interlocked molecule was identified by HRMS and NMR techniques, the latter revealing patterns of signals similar to those observed previously for rotaxanes of this type. 14,15,25,61…”

“…Dibenzo-24-crown-8 ether (DB24C8) is one of the iconic macrocycles in supramolecular chemistry. Its use in the assembly of pseudorotaxanes [1][2][3][4][5][6][7][8][9][10][11][12][13] and mechanically interlocked molecules (MIMs) [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] is widespread. The derivatives of DB24C8 play an equally important role; they are usually prepared by macrocyclization of the DB24C8 scaffold from appropriate pre-functionalized starting materials.…”