Over the past two decades, supramolecular gels have attracted significant attention from scientists in diverse research fields and have been extensively developed. This review mainly focuses on the significant achievements in supramolecular gels and catalysis. First, by incorporating diverse catalytic sites and active organic functional groups into gelator molecules, supramolecular gels have been considered as a novel matrix for catalysis. In addition, these rationally designed supramolecular gels also provide a variety of templates to access metal nanocomposites, which may function as catalysts and exhibit high activity in diverse catalytic transformations. Finally, as a new kind of biomaterial, supramolecular gels formed in situ by self-assembly triggered by catalytic transformations are also covered herein.
The option of conjugated π-linkers
is critical for molecular
engineering toward the energy-level strategy of donor−π–acceptor
(D−π–A) sensitizers. There is always a balance
in the optimization of a π-linker. The π-conjugation should
be enlarged to expand the light-harvesting capability of sensitizers
for an increase in photocurrent; however, the oversized π-linker
also would affect seriously the photovoltage and photostability. Two
sensitizers, WS-22 and WS-23, are constructed
without or with benzothiadiazole (BTD) in a molecular skeleton, aiming
to gain insight into the effect of an auxiliary acceptor in D–A−π–A
sensitizers on the photophysical and photovoltaic performances, especially
focusing on the exploitation of the short circuit current density
(J
sc) and open circuit voltage (V
oc). Compared with the typical D−π–A
sensitizer WS-22, the incorporation of an auxiliary acceptor
of BTD in WS-23 can improve the light-harvesting ability
both in red-shifting the absorption peaks and the increment of absorption
coefficient. The predominant increase by 15.6% in light-harvesting
efficiency (LHE) of WS-23 results in a relatively higher J
sc from 13.77 (WS-22) to 16.91
mA cm–2 (WS-23). Moreover, the improvement
of the V
oc in WS-23 is originated
by a synergy contribution of the uplifting of E
CB and inhibition of charge recombination. The stepped light-induced
transient (SLIT) measurements indicate that the introduction of BTD
can negatively shift the conduction band of the TiO2 film.
For WS-23, the higher molecular dipole moment can bring forth a more effective charge
separation between donor and acceptor units, also resulting in an
increase in V
oc. The incorporated BTD
unit can increase V
oc by 57 mV, arising
from the CB edge shift of TiO2 (accounting for 40%, 23
mV) and the retarding charge recombination (accounting for 60%, 34
mV). As a consequence, WS-23 realizes an optimizing photovoltaic
efficiency (η = 8.15%), with an improvement of 36.5% with respect
to WS-22.
A single-step gold(I)-catalyzed
chemoselective protocol to access ortho-substituted
diarylsulfones has been established. Acenaphthoimidazolylidene
gold complexes are effective catalysts for the arylsulfonylation of
boronic acids by potassium metabisulfite (K2S2O5) and diaryliodonium salts to access (poly-)ortho-substituted diarylsulfones even in gram scale. Unlike
the transition metal-catalyzed two-component coupling systems, the
sterically hindered aryl groups in diaryliodonium salts are preferentially
transferred over less bulky ones to form synthetically difficult targets,
including those of pharmaceutical importance.
Lowering the LUMOs and decreasing energy “waste” is targeted through inserting an auxiliary group from an electron donor or acceptor into D–π–A organic sensitizers, and the photovoltaic efficiency increases 38 fold from 0.24 to 9.46%.
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