AP-TPE at 525 nm showed a clear increase. The host–guest recognition restricts the
intramolecular rotation of AIEgens, and thus non-radiative pathway is blocked,
which further causes a visible fluorescence enhancement [10, 11]. In this case,
after the first acidification, dibenzylammonium salts (DBAs) bound with dibenzo24-crown-8(DB24C8) to form polar groups. Benefiting from the solvophobic effect,
the host–guest complex formed a micelle with the polar groups located on the inner
side. The subsequent reaction product further promoted the aggregation named
salting-out effect.
Recent studies showed that ammonium and its derivatives have been utilized as
proton conductors in ionic liquids [12] and metal–organic frameworks [13], respectively. Bu et al. reported some supramolecular connection mode forms with twodimensional ionic channels that show controllable and appreciable proton-conducting
behaviors. The starlike polymer of poly(E-caprolactone dibenzylammonium salt
(PCL-DBA) contained four DBA-terminated poly(E-caprolactone (PCL) arms. The
supramolecular network (Mo132-PCL and W12-PCL) was also obtained using
PCL-DBA and DB24C8, where their molar ratio was controlled as 1:1. Considering
that the present proton conductivity is originated from the NH 2
+ group, the increases in
the proton conductivities of both W12-PCL and Mo132-PCL should arise from the
aforementioned formation of [2]pseudorotaxanes between DBA ion and DB24C8
group, leading to the formation of supramolecular networks. Conductive AFM images
showed that the patterns were electrically pronounced in a pA range. This is the first
report that secondary dialkylammonium salt/crown ether [2]pseudorotaxanes were
utilized as proton conductors (Fig. 2) [14].
Yan et al. reported a bis(p-phenylene)-34-crown-10 (BPP34C10) derivative
bearing two pyridyl groups and studied its binding to paraquat and
2,7-diazapyrenium derivative (DAP) (Fig. 3) [15]. Upon the addition of di-Pt(II)
acceptor, poly[2]pseudorotaxanes were formed. The themes of coordinationdriven self-assembly, host–guest interactions, and supramolecular polymerization
are unified in an orthogonal manner. It was found that the binding ability of DAP
to the crown ether is stronger than that of paraquat. Interestingly, after DAP was
added into polypseudorotaxane, the more stable polypseudorotaxane was formed.
The dynamical and reversible supramolecular polymer backbone with reversibility and adaptability makes it potentially useful in areas such as stimuli-responsive
materials.
During the past two decades, the Gibson team has been working on
polypseudorotaxanes based on crown ethers. In 1998, they reported a polypseudorotaxane by threading linear paraquat through the cavities of cyclic repeated
units of polymacrocycle. The change of color and proton NMR spectroscopy could
validate the formation of polypseudorotaxane. With increasing amounts of paraquat,
m/n value of polypseudorotaxane increased, as well as with decreasing temperature.
The values of ΔS, K, and ΔH provided the foundation for predicting the m/n values
for the preparation of analogous systems [16]. To further expand the research, they
built the first supramolecular comblike graft copolymer based on pseudorotaxane
constructed from two polymeric building blocks: a paraquat-terminated polystyrene
and a main-chain crown ether polyester (Fig. 4) [17]. Introduction of appropriate
2 Polypseudorotaxanes Constructed by Crown Ethers
29
intramolecular rotation of AIEgens, and thus non-radiative pathway is blocked,
which further causes a visible fluorescence enhancement [10, 11]. In this case,
after the first acidification, dibenzylammonium salts (DBAs) bound with dibenzo24-crown-8(DB24C8) to form polar groups. Benefiting from the solvophobic effect,
the host–guest complex formed a micelle with the polar groups located on the inner
side. The subsequent reaction product further promoted the aggregation named
salting-out effect.
Recent studies showed that ammonium and its derivatives have been utilized as
proton conductors in ionic liquids [12] and metal–organic frameworks [13], respectively. Bu et al. reported some supramolecular connection mode forms with twodimensional ionic channels that show controllable and appreciable proton-conducting
behaviors. The starlike polymer of poly(E-caprolactone dibenzylammonium salt
(PCL-DBA) contained four DBA-terminated poly(E-caprolactone (PCL) arms. The
supramolecular network (Mo132-PCL and W12-PCL) was also obtained using
PCL-DBA and DB24C8, where their molar ratio was controlled as 1:1. Considering
that the present proton conductivity is originated from the NH 2
+ group, the increases in
the proton conductivities of both W12-PCL and Mo132-PCL should arise from the
aforementioned formation of [2]pseudorotaxanes between DBA ion and DB24C8
group, leading to the formation of supramolecular networks. Conductive AFM images
showed that the patterns were electrically pronounced in a pA range. This is the first
report that secondary dialkylammonium salt/crown ether [2]pseudorotaxanes were
utilized as proton conductors (Fig. 2) [14].
Yan et al. reported a bis(p-phenylene)-34-crown-10 (BPP34C10) derivative
bearing two pyridyl groups and studied its binding to paraquat and
2,7-diazapyrenium derivative (DAP) (Fig. 3) [15]. Upon the addition of di-Pt(II)
acceptor, poly[2]pseudorotaxanes were formed. The themes of coordinationdriven self-assembly, host–guest interactions, and supramolecular polymerization
are unified in an orthogonal manner. It was found that the binding ability of DAP
to the crown ether is stronger than that of paraquat. Interestingly, after DAP was
added into polypseudorotaxane, the more stable polypseudorotaxane was formed.
The dynamical and reversible supramolecular polymer backbone with reversibility and adaptability makes it potentially useful in areas such as stimuli-responsive
materials.
During the past two decades, the Gibson team has been working on
polypseudorotaxanes based on crown ethers. In 1998, they reported a polypseudorotaxane by threading linear paraquat through the cavities of cyclic repeated
units of polymacrocycle. The change of color and proton NMR spectroscopy could
validate the formation of polypseudorotaxane. With increasing amounts of paraquat,
m/n value of polypseudorotaxane increased, as well as with decreasing temperature.
The values of ΔS, K, and ΔH provided the foundation for predicting the m/n values
for the preparation of analogous systems [16]. To further expand the research, they
built the first supramolecular comblike graft copolymer based on pseudorotaxane
constructed from two polymeric building blocks: a paraquat-terminated polystyrene
and a main-chain crown ether polyester (Fig. 4) [17]. Introduction of appropriate
2 Polypseudorotaxanes Constructed by Crown Ethers
29