2 research outputs found
Reversibly Tunable Lower Critical Solution Temperature Utilizing Host–Guest Complexation of Pillar[5]arene with Triethylene Oxide Substituents
A thermoresponsive macromolecule consisting of 10 outer
triethylene
oxide groups and a pillar[5]Âarene core was prepared. The macromolecule
showed lower critical solution temperature behavior. Moreover, its
clouding point can be reversibly tuned based on the addition of guest
and host compounds; the clouding point increased upon addition of
a guest didecylviologen salt and decreased when the competitive host
cucurbit[7]Âuril was added
Cyclic Host Liquids for Facile and High-Yield Synthesis of [2]Rotaxanes
We developed “cyclic host liquids (CHLs)”
as a new
type of solvent. The CHLs are a nonvolatile liquid over a wide temperature
range, are biocompatible and recyclable, have high thermal stability,
and are miscible with many organic solvents. Compared with typical
complexation systems, the CHL system is extremely efficient for maintaining
host–guest complexation because an additional solvent is not
required. Based on the efficient host–guest complexation in
the CHL system, we demonstrated synthesis of [2]Ârotaxanes in pillar[5]Âarene-based
CHL. High yields were obtained for [2]Ârotaxanes capped by cationization
(yield 91%) and Huisgen reaction (yield 88%) between the axle and
the stopper components in the CHL system, while the association constants
between the axles and wheels were quite low (10–15 M<sup>–1</sup>) in CDCl<sub>3</sub>. The CHL system provides a new powerful approach
for synthesis of mechanically interlocked molecules (MIMs) even with
unfavorable statistical combinations of host–guest complexes