Pseudopolyrotaxanes Made to Order:  Cucurbituril Threaded on Polyviologen

Abstract

Pseudopolyrotaxane 2 is synthesized from polyviologen (1) and cucurbituril (CB[6]) in water by simple stirring at room temperature. The degree of threading (number of CB[6] beads per repeat unit) can be precisely controlled from 0.1 to 1.0 by controlling the amount of CB[6] added. In 2, CB[6] beads are localized at the middle of the decamethylene units of the polymer through hydrophobic and charge − dipole interactions, to afford a well-defined microstructure in aqueous medium as found by NMR studies. The pseudopolyrotaxane has higher intrinsic viscosity, but a lower shape-dependent Huggins constant, than the parent polymer. This is attributed to a larger hydrodynamic radius and more expanded chain conformation of the pseudopolyrotaxane compared to those of the parent polymer. The decomposition temperature of 2 increases with increasing amount of CB[6] threaded on the polymer.

The Cucurbit[n]uril Family

“…[186] CB [6]-based rotaxanes have been prepared in solution by dipolar cycloadditions, [147,[150][151][152]187] stoppering with dinitrophenyl groups, [188] amide-bond formation, [189][190][191][192][193] ionic interactions, [194] and coordination of alkylcobaloximes. [195,196] A variety of polymer backbones and side chains have been threaded with CB [6] beads including polyacrylamides and polystyrenes, [197] poly(hexamethyleneimine), [151,198] di-and polyviologen, [98,199] and poly(propyleneimine) dendrimers. [200] A rotaxane derived from Ph 2 CB [6] (see Section 8.4) was stoppered with dinitrophenyl groups, [201] the CB [5]·spermine pseudorotaxane has been stoppered with benzoyl and furoyl groups, [202] and Newkome-type dendritic wedges containing viologen focal point functionality have been threaded with CB [7].…”

Directed 1D Assembly of a Ring‐Shaped Inorganic Nanocluster Templated by an Organic Rigid‐Rod Molecule: An Inorganic/Organic Polypseudorotaxane

“…From these observations, the 1D structure formed from MC and PB 14 may be called an inorganic/organic polypseudorotaxane. [7][8][9][10][11] In conclusion, we have demonstrated the formation of the first inorganic/organic polypseudorotaxane by the templateassisted cofacial assembly of a ring-shaped molybdenum cluster (MC) with a rigid-rod molecule having a high affinity toward the MC surface. Since the MC is a mixed-valent inorganic cluster with chromophoric characteristics, exploration of the optoelectronic properties of this novel 1D nanocomposite material is one of the subjects worthy of further investigation.…”

“…On the basis of this observation, PB n was designed with the expectation that it may connect multiple MC rings in a cofacial manner through electrostatic interactions to form a one-dimensional structure. [7][8][9][10][11] For the synthesis of PB n , a 1,4-diethynylbenzene derivative with four tert-butoxycarbonyl-protected amino groups ( Boc PB 1 ) was subjected to Cu II -mediated Glaser-Hey coupling. The high-molecular-weight fraction of the resultant polymer ( Boc PB n ) was isolated by preparative size-exclusion chromatography (SEC) and then deprotected with trifluoroacetic acid (TFA).…”

Cucurbiturilas

“…A partir daí é possível criar estruturas maiores, como polirotaxanos [82][83][84] e polipseudorotaxanos 85 ou até catenanos, dependendo da natureza dos grupos bloqueadores terminais, do procedimento de síntese e da natureza de seus eixos. Geralmente procede-se, com o CB [6], a cicloadições dipolares com grupos dinitrofenila e à formação de amidas, entre outras, para criar grupo bloqueantes em pseudo-rotaxanos.…”