The sunlight-driven
reduction of CO
2
into carbonaceous
fuels can lower the atmospheric CO
2
concentration and provide
renewable energy simultaneously, attracting scientists to design photocatalytic
systems for facilitating this process. Significant progress has been
made in designing high-performance photosensitizers and catalysts
in this regard, and further improvement can be realized by installing
additional interactions between the abovementioned two components,
however, the design strategies and mechanistic investigations on such
interactions remain challenging. Here, we present the construction
of molecular models for intermolecular π–π interactions
between the photosensitizer and the catalyst, via the introduction
of pyrene groups into both molecular components. The presence, types,
and strengths of diverse π–π interactions, as well
as their roles in the photocatalytic mechanism, have been examined
by
1
H NMR titration, fluorescence quenching measurements,
transient absorption spectroscopy, and quantum chemical simulations.
We have also explored the rare dual emission behavior of the pyrene-appended
iridium photosensitizer, of which the excited state can deliver the
photo-excited electron to the pyrene-decorated cobalt catalyst at
a fast rate of 2.60 × 10
6
s
–1
via
co-facial π–π interaction, enabling a remarkable
apparent quantum efficiency of 14.3 ± 0.8% at 425 nm and a high
selectivity of 98% for the photocatalytic CO
2
-to-CO conversion.
This research demonstrates non-covalent interaction construction as
an effective strategy to achieve rapid CO
2
photoreduction
besides a conventional photosensitizer/catalyst design.
Histoplasmosis is an endemic disease mainly occurring in North America and is rare in China. Confirmation of histoplasmosis should be based on a compatible clinical scenario and a positive culture or histopathology. However, there are still many cases that are misdiagnosed or missed, especially in individuals from non-endemic areas. In recent years, metagenomic next-generation sequencing (mNGS) has led to the accurate and timely diagnosis of some rare and complicated infectious diseases. We describe the case of a 27-year-old Chinese man who had chronic progressive pulmonary lesions without any symptoms for more than 1 year, until the lesions reached the epiglottis and led to progressive pharyngeal pain. There were no positive results from bronchoalveolar lavage fluid (BALF) and epiglottis tissue cultures, or from epiglottis and lung pathological examinations, but mNGS was able to identify Histoplasma capsulatum in the epiglottis tissues and BALF as the cause of the lesions. The patient was treated successfully with itraconazole.
The design of a highly efficient system for CO
2
photoreduction fully based on earth-abundant elements presents a challenge, which may be overcome by installing suitable interactions between photosensitizer and catalyst to expedite the intermolecular electron transfer. Herein, we have designed a pyrene-decorated Cu(I) complex with a rare dual emission behavior, aiming at additional π-interaction with a pyrene-appended Co(II) catalyst for visible light–driven CO
2
-to-CO conversion. The results of
1
H NMR titration, time-resolved fluorescence/absorption spectroscopies, quantum chemical simulations, and photocatalytic experiments clearly demonstrate that the dynamic π–π interaction between sensitizer and catalyst is highly advantageous in photocatalysis by accelerating the intermolecular electron transfer rate up to 6.9 × 10
5
s
−1
, thus achieving a notable apparent quantum yield of 19% at 425 nm with near-unity selectivity. While comparable to most earth-abundant molecular systems, this value is over three times of the pyrene-free system (6.0%) and far surpassing the benchmarking Ru(II) tris(bipyridine) (0.3%) and Ir(III) tris(2-phenylpyridine) (1.4%) photosensitizers under parallel conditions.
Improving the photocatalytic efficiency of a fully noble-metal-free
system for CO2 reduction remains a fundamental challenge,
which can be accomplished by facilitating electron delivery as a consequence
of exploiting intermolecular interactions. Herein, we have designed
two Cu(I) photosensitizers with different pyridyl pendants at the
phenanthroline moiety to enable dynamic coordinative interactions
between the sensitizers and a cobalt macrocyclic catalyst. Compared
to the parent Cu(I) photosensitizer, one of the pyridine-tethered
derivatives boosts the apparent quantum yield up to 76 ± 6% at
425 nm for selective (near 99%) CO2-to-CO conversion. This
value is nearly twice that of the parent system with no pyridyl pendants
(40 ± 5%) and substantially surpasses the record (57%) of the
noble-metal-free systems reported so far. This system also realizes
a maximum turnover number of 11 800 ± 1400. In contrast,
another Cu(I) photosensitizer, in which the pyridine substituents
are directly linked to the phenanthroline moiety, is inactive. The
above behavior and photocatalytic mechanism are systematically elucidated
by transient fluorescence, transient absorption, transient X-ray absorption
spectroscopies, and quantum chemical calculations. This work highlights
the advantage of constructing coordinative interactions to fine-tune
the electron transfer processes within noble-metal-free systems for
CO2 photoreduction.
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