An organic crystal of 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl (pCBP) exhibits time‐dependent afterglow color from blue to orange over 1 s. Both experimental and computational data confirm that the color ...evolution results from well‐separated, long‐persistent thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP) with different but comparable decay rates. TADF is enabled by a small S1–T1 energy gap of 0.7 kcal mol−1. The good separation of TADF and RTP is due to a 11.8 kcal mol−1 difference in the S0 energies of the S1 and T1 structures, indicating that apart from the excited‐state properties, tuning the ground state is also important for luminescence properties. This afterglow color evolution of pCBP allows its applications in anticounterfeiting and data encryption with high security levels.
Organic sunset: A time‐dependent afterglow color in a single‐component organic molecular crystal was observed. It originates from well‐separated, long‐persistent thermally activated delayed fluorescence and room‐temperature phosphorescence with different but comparable decay rates.
Developing Type‐I photosensitizers is considered as an efficient approach to overcome the deficiency of traditional photodynamic therapy (PDT) for hypoxic tumors. However, it remains a challenge to ...design photosensitizers for generating reactive oxygen species by the Type‐I process. Herein, we report a series of α,β‐linked BODIPY dimers and a trimer that exclusively generate superoxide radical (O2−.) by the Type‐I process upon light irradiation. The triplet formation originates from an effective excited‐state relaxation from the initially populated singlet (S1) to triplet (T1) states via an intermediate triplet (T2) state. The low reduction potential and ultralong lifetime of the T1 state facilitate the efficient generation of O2−. by inter‐molecular charge transfer to molecular oxygen. The energy gap of T1‐S0 is smaller than that between 3O2 and 1O2 thereby precluding the generation of singlet oxygen by the Type‐II process. The trimer exhibits superior PDT performance under the hypoxic environment.
Heavy‐atom‐free boron dipyrromethene (BODIPY)‐based photosensitizers generate ROS exclusively by the Type‐I process upon near‐infrared light illumination for tumor ablation.
The capacitance of microsupercapacitors (MSCs) can double if both sides of substrates are used to construct MSCs. Nevertheless, achieving electric connections of MSCs through substrates is a ...challenge due to the difficulty in precisely positioning each MSC couple that has two of the same MSCs units on two sides. In this work, taking advantage of the synchronous etching on both sides of transparent polyethylene terephthalate substrates by femtosecond laser pulses, a double‐sided configuration is attained with high precision in the alignment of back‐to‐back MSC couples and versatile double‐side MSCs are realized via arbitrary on‐ and through‐substrate connections of MXene MSC units. The MXene double‐side MSC fabricated by the series connection of 12 spiral pattern MXene MSC units with interdigital electrodes of 10 μm width interspace can output a large working voltage of 7.2 V. Additionally, femtosecond laser etching brings the transformation of MXene into titania near‐etched edges with a lateral distance less than 1 µm. Such a small laser‐affected area has little influence on the capacitive performance, which is one of advantages for femtosecond laser over conventional lasers. This research is valuable for one‐step manufacturing of highly integrated MSCs in the field of miniaturized energy storage systems.
This study proposes the fabrication of MXene microsupercapacitors with a double‐sided configuration by synchronous femtosecond laser etching on both sides of transparent polyethylene terephthalate substrate. Such a double‐side configuration can double the integration level compared to routine one‐side configuration.
•A review on carbon-based nanomaterials’ applications in sample preparation.•Particular attention is paid to graphene for its growing papers recently.•Research status and perspective of them are also ...discussed.
In this paper, a broad overview on the applications of different carbon-based nanomaterials, including nanodiamonds, fullerenes, carbon nanotubes, graphene, carbon nanofibers, carbon nanocones-disks and nanohorns, as well as their functionalized forms, in sample preparation is provided. Particular attention has been paid to graphene because many papers regarding its application in this research field are becoming available. The distinctive properties, derivatization methods and application techniques of these materials were summarized and compared. According to their research status and perspective, these nanomaterials were classified in four groups (I: graphene and carbon nanotubes; II: carbon nanofibers; III: fullerenes; and IV: nanodiamonds, carbon nanocones/disks and carbon nanohorns) and characteristics and future trends of every group were discussed.
The facile synthesis of stereo‐defined and transformable functionality‐enriched building blocks is of great importance in modern organic chemistry, as it allows the rapid and divergent assembly of ...complex molecules. Herein a halogen electrophile (N‐bromosuccinimide and N‐iodosuccinimide) initiated semipinacol rearrangement reaction of B(MIDA)‐propargylic alcohols (MIDA=N‐methyliminodiacetyl) by aryl migration towards the synthesis of amphoteric α‐haloalkenyl boronates in moderate to good yields with excellent stereoselectivities is reported. The value of the products is evidenced by their ability to undergo divergent conversions to polysubstituted alkenes through manipulation of the C−B and C−X (X=Br, I) bonds and the carbonyl group.
A halogen‐induced halogenative semipinacol rearrangement of B(MIDA)‐propargylic alcohols is reported herein. The reaction proceeded under mild conditions to access a variety of synthetically valuable carbonyl‐containing α‐haloalkenyl boronates with moderate to good yields and excellent stereoselectivities.
H3.3 is a histone variant, which is deposited on genebodies and regulatory elements, by Hira, marking active transcription. Moreover, H3.3 is deposited on heterochromatin by Atrx/Daxx complex. The ...exact role of H3.3 in cell fate transition remains elusive. Here, we investigate the dynamic changes in the deposition of the histone variant H3.3 during cellular reprogramming. H3.3 maintains the identities of the parental cells during reprogramming as its removal at early time-point enhances the efficiency of the process. We find that H3.3 plays a similar role in transdifferentiation to hematopoietic progenitors and neuronal differentiation from embryonic stem cells. Contrastingly, H3.3 deposition on genes associated with the newly reprogrammed lineage is essential as its depletion at the later phase abolishes the process. Mechanistically, H3.3 deposition by Hira, and its K4 and K36 modifications are central to the role of H3.3 in cell fate conversion. Finally, H3.3 safeguards fibroblast lineage by regulating Mapk cascade and collagen synthesis.
Herein, a chemiluminescence assay with dual signal amplification has been developed based on multi-DNAzymes-functionalized gold nanoparticles (AuNPs) using in situ rolling circle amplification (RCA) ...for ultrasensitive detection of thrombin on microchip. In this assay, AuNPs was functionalized by aptamer and multi-RCA primer for amplification, and thrombin was sandwiched between the aptamer modified on the microchannel and the aptamer linked AuNP. The further amplification was realized by in situ RCA to expand specific oligonucleotides chains on the AuNPs and produce particular multi-DNAzymes. Enhanced chemiluminescence signal was achieved by the catalytic effect of DNAzymes in the luminol-H2O2 system. The sensitivity of detection was greatly improved by the dual amplification of multi-RCA primer modified AuNPs, and RCA. The whole strategy was applied for ultrasensitive and specific detection of thrombin. The chemiluminesce assay of thrombin performed a good linear range of 1–25 pM and the limit of detection was as low as 0.55 pM. The successful determination of thrombin in real human serum sample indicated a great potential in clinical study.
Ultrasensitive thrombin detection by chemiluminescence via a dual signal amplification strategy of functionalized gold nanoparticles and rolling circle amplification. Display omitted
•Ultrasensitive chemiluminesence assay realized by dual signal amplification strategy.•Multichannel microchip increased reaction efficiency and reduced detection time.•Thrombin in serum could be sensitively, selectively and rapidly determined.
Atmospheric ozone has long been a threat to human health, however, rational design of high-performance O
-decomposition catalysts remains challenging. Herein, we demonstrate the great potential of a ...series of isomorphous bimetallic MOFs denoted as PCN-250(Fe
M) (M = Co
, Ni
, Mn
) in catalytic O
decomposition. Particularly, PCN-250(Fe
Co) showed 100% O
removal efficiency for a continuous air flow containing 1 ppm O
over a wide humidity range (0 ‒ 80% RH) at room temperature. Mechanism studies suggested that the high catalytic performance originated from the introduction of open Co(II) sites as well as its porous structure. Additionally, at low pressures around 10 Pa, PCN-250(Fe
Co) exhibited high adsorption capacities (89 ‒ 241 mg g
) for most VOCs, which are not only a class of hazardous air pollutants but also the precursor of O
. This work opens up a new avenue to develop advanced air purification materials for O
and VOCs removal in one.
Photoassisted steam reforming and dry (CO2) reforming of methane (SRM and DRM) at room temperature with high syngas selectivity have been achieved in the gas‐phase catalysis for the first time. The ...catalysts used are bimetallic rhodium–vanadium oxide cluster anions of Rh2VO1–3−. Both the oxidation of methane and reduction of H2O/CO2 can take place efficiently in the dark while the pivotal step to govern syngas selectivity is photo‐excitation of the reaction intermediates Rh2VO2,3CH2− to specific electronically excited states that can selectively produce CO and H2. Electronic excitation over Rh2VO2,3CH2− to control the syngas selectivity is further confirmed from the comparison with the thermal excitation of Rh2VO2,3CH2−, which leads to diversity of products. The atomic‐level mechanism obtained from the well‐controlled cluster reactions provides insight into the process of selective syngas production from the photocatalytic SRM and DRM reactions over supported metal oxide catalysts.
Steam and dry reforming of methane catalyzed by gas‐phase rhodium–vanadium–oxygen cluster anions at room temperature with high syngas selectivity has been identified under photo‐irradiation conditions. The crucial step to govern syngas selectivity is the photo‐excitation of reaction intermediates such as Rh2VO3CH2− to electronically excited states that selectively produce H2 and CO.
The underlying mechanism for non‐oxidative methane aromatization remains controversial owing to the lack of experimental evidence for the formation of the first C−C bond. For the first time, the ...elementary reaction of methane with atomic clusters (FeC3−) under high‐temperature conditions to produce C−C coupling products has been characterized by mass spectrometry. With the elevation of temperature from 300 K to 610 K, the production of acetylene, the important intermediate proposed in a monofunctional mechanism of methane aromatization, was significantly enhanced, which can be well‐rationalized by quantum chemistry calculations. This study narrows the gap between gas‐phase and condensed‐phase studies on methane conversion and suggests that the monofunctional mechanism probably operates in non‐oxidative methane aromatization.
Generation of acetylene, the C−C coupling product in the high‐temperature reaction of methane with atomic cluster species (FeC3−), has been identified. This provides a molecular level origin of the monofunctional mechanism for non‐oxidative methane aromatization proposed in condensed phase systems.
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