2 research outputs found
<i>N</i>‑Heterocyclic Carbene-Based Conducting Polymer–Gold Nanoparticle Hybrids and Their Catalytic Application
Hybrid
nanocomposites of <i>N</i>-heterocyclic carbene
(NHC)-functionalized conducting polymers (CPs) with gold nanoparticles
(AuNPs) were prepared by concurrent disproportionation and oxidative
coupling. The formation of hybrid nanocomposites, NHC-CP/AuNPs, in
the simultaneous process was confirmed by transmission electron microscopy,
powder X-ray diffraction, cyclic voltammetry, and <sup>13</sup>C solid-state
NMR analyses. More importantly, the NHC group played a pivotal role
in the dispersion of AuNPs. Further, NHC-CP/AuNPs exhibited good catalytic
activity for the reduction of 4-nitrophenol
Torsionally Responsive Tropone-Fused Conjugated Polymers
Torsionally responsive molecular
systems can change their electronic
properties according to the dihedral angles and can be utilized as
sensory materials. We have designed and synthesized novel tropone-fused
conjugated polymers <b>PBTr</b>, <b>PBTr-T</b>, and <b>PBTr-Tz</b> that showed interesting dihedral-angle-dependent variations
in UV–vis absorptions. Tropone-fused thiophene derivatives
were prepared from one-step condensation of thiophene-3,4-dialdehyde
and aliphatic ketones via a modular, facile, and high-yielding method.
Subsequent halogenation and Stille cross-coupling polymerization with
a bisÂ(stannyl)ÂbenzoÂdithiophene resulted in a tropone-fused conjugated
polymer <b>PBTr</b>. We were also able to prepare thiophene-
and thiazole-bridged polymers, <b>PBTr-T</b> and <b>PBTr-Tz</b>, respectively, using similar synthetic methods. Electronic absorptions
of the newly synthesized <b>PBTrs</b> were measured in solutions
and in films states. Substantial red-shifts occurred in the case of
thiophene-bridged <b>PBTr-T</b>, whereas almost no shift was
observed for thiazole-bridged <b>PBTr-Tz</b>. We attributed
this to the substantial change in the torsional angle between the
tropone-fused thiophene moiety and thiophene, which was further supported
by density functional theory (DFT) calculations. Similar spectral
changes of UV–vis absorptions were observed when a poor solvent
(methanol) was introduced to a chloroform solution of <b>PBTr-T</b>. Reverse torsional angle variations were realized with initially
planar <b>PBTr-Tz</b> by introducing steric hindrance through
protonation on the thiazole rings. We believe that torsionally responsive
tropone-fused conjugated polymers are promising as novel platforms
for sensory applications