Realizing highly efficient deep-blue organic light-emitting diodes towards Rec.2020 chromaticity by restricting the vibration of the molecular framework.

Deep-blue organic light-emitting diodes (OLEDs) with narrow emission spectra and high efficiency, meeting the Rec.2020 standard, hold significant promise in the realm of 4K/8K ultrahigh-definition displays. However, the development of light-emitting materials exhibiting both narrowband emission and high efficiency, particularly in the realm of deep-blue thermally activated delayed fluorescence (TADF), confronts substantial challenges. Herein, a novel deep-blue TADF emitter, named BOC-PSi, was designed by integrating a rigid B-heterotriangulene acceptor (A) with a rigid phenazasiline donor (D). The replacement of a sp3 carbon atom with a sp3 silicon atom in the D moiety helps to restrict the low-frequency bending vibration throughout the entire D-A molecular backbone, while concurrently accelerating the multi-channel reverse intersystem crossing (RISC) processes. Notably, OLEDs using the BOC-PSi emitter exhibit exceptional performance, with a high maximum external quantum efficiency (EQEmax) approaching 20%, and a superior color purity closely aligning with the Rec.2020 blue standard.

A spiroacridine-based thermally activated delayed fluorescence emitter for high-efficiency and narrow-band deep-blue OLEDs.

A novel deep-blue thermally activated delayed fluorescence molecule of SAC-BOC was reported. The SAC-BOC-based device exhibits a narrow full width at half maximum of 57 nm, an impressive maximum external quantum efficiency (EQEmax) of 15.3% and CIE coordinates of (0.144, 0.129).

Acquiring Charge-Transfer-Featured Single-Molecule Ultralong Organic Room Temperature Phosphorescence via Through-Space Electronic Coupling.

Although long-lived triplet charge-transfer (3 CT) state with high energy level has gained significant attention, the development of organic small molecules capable of achieving such states remains a major challenge. Herein, by using the through-space electronic coupling effect, we have developed a compound, namely NIC-DMAC, which has a long-lived 3 CT state at the single-molecule level with a lifetime of 210 ms and a high energy level of up to 2.50 eV. Through a combination of experimental and computational approaches, we have elucidated the photophysical processes of NIC-DMAC, which involve sequential transitions from the first singlet excited state (S1 ) that shows a 1 CT character to the first triplet excited state (T1 ) that exhibits a local excited state feature (3 LE), and then to the second triplet excited state (T2 ) that shows a 3 CT character (i.e., S1 (1 CT)→T1 (3 LE)→T2 (3 CT)). The long lifetime and high energy level of its 3 CT state have enabled NIC-DMAC as an initiator for photocuring in double patterning applications.

A Reusable Fluorescent Molecular Self-Assembly Cage for Simultaneous Detection and Recycling of Silver(I) Ion.

Although molecular self-assembled porous materials capable of ratiometric fluorescence probing and recycling of metal ions are both economically and environmentally attractive, very few current efforts have been devoted. Herein, we demonstrated a three-dimensional pure organic cage, namely 4-cage, which can serve as a fluorescent probe for simultaneous ratiometric detection and recycling of Ag+ ion. Taking advantage of the promising emission behavior of its rigidified tetraphenylethylene scaffolds and the chelating ability of its dynamically reversible imine moieties, on one hand, upon the addition of Ag+ , 4-cage undergoes coordination to form a stable but poorly soluble fluorescent complex, Ag+ @4-cage, accompanied by a fluorescence color change from bluish-green to yellowish-green. This allows us to differentiate Ag+ from other cations with high selectivity. On the other hand, upon the addition of Cl- anion, Ag+ @4-cage can be effectively converted into free 4-cage due to the competitive coordination of Cl- with Ag+ . Through this process, secondary usage of 4-cage and the recycling of Ag+ ion can be achieved.

Photoswitchable and long-lived seven-membered cyclic singlet diradicals for the bioorthogonal photoclick reaction.

Annularly 1,3-localized singlet diradicals are energetic and homolytic intermediates, but commonly too short-lived for widespread utilization. Herein, we describe a direct observation of a long-lived and seven-membered singlet diradical, oxepine-3,6-dione-2,7-diyl (OXPID), via spectroscopic experiments and also theoretical evidence from computational studies, which is generated via photo-induced ring-expansion of 2,3-diaryl-1,4-naphthoquinone epoxide (DNQO). The photo-generated OXPID reverts to the thermally stable σ-bonded DNQO with t1/2 in the µs level, thus constituting a novel class of T-type molecular photoswitches with high light-energy conversion efficiency (η = 7.8-33%). Meanwhile, the OXPID is equilibrated to a seven-membered cyclic 1,3-dipole as an electronic tautomer that can be captured by ring-strained dipolarophiles with an ultrafast cycloaddition rate (k2CA up to 109 M-1 s-1). The T-type photoswitchable DNQO is then exploited to be a highly selective and recyclable photoclick reagent, enabling spatiotemporal-resolved bioorthogonal ligation on living cell membranes via a tailored DNQO-Cy3 probe.

Corrigendum: Complete genome sequence of biocontrol strain Bacillus velezensis YC89 and its biocontrol potential against sugarcane red rot.

[This corrects the article DOI: 10.3389/fmicb.2023.1180474.].

Synthesis and real-time monitoring of the morphological evolution of luminescent Eu(TCPP) MOFs.

Real-time acquisition of the morphological information of nanomaterials is crucial to achieving morphological controllable synthesis, albeit being challenging. A novel device was designed, which integrated dielectric barrier discharge (DBD) plasma synthesis and simultaneous in situ spectral monitoring of the formation of metal-organic frameworks (MOFs). Important dynamic luminescence behaviors such as coordination induced emission (CIE), antenna effect (AE), and red-blue shift were continuously captured to reveal the spectral emission mechanism and energy transfer progress and verify the correlation with the morphological evolution of the MOFs. The prediction and control of morphology were successfully achieved with Eu(TCPP) as a model MOF. The proposed method will shed new light on exploring the spectral emission mechanism, energy conversion and in situ morphology monitoring of other luminescent materials.

Complete genome sequence of biocontrol strain Bacillus velezensis YC89 and its biocontrol potential against sugarcane red rot.

Introduction: Sugarcane is one of the most important sugar crops worldwide, however, sugarcane production is seriously limited by sugarcane red rot, a soil-borne disease caused by Colletotrichum falcatum. Bacillus velezensis YC89 was isolated from sugarcane leaves and can significantly inhibited red rot disease caused by C. falcatum. Methods: In this study, the genome of YC89 strain was sequenced, its genome structure and function were analyzed using various bioinformatics software, and its genome was compared with those of other homologous strains. In addition, the effectiveness of YC89 against sugarcane red rot and the evaluation of sugarcane plant growth promotion were also investigated by pot experiments. Results: Here, we present the complete genome sequence of YC89, which consists of a 3.95 Mb circular chromosome with an average GC content of 46.62%. The phylogenetic tree indicated that YC89 is closely related to B. velezensis GS-1. Comparative genome analysis of YC89 with other published strains (B. velezensis FZB42, B. velezensis CC09, B. velezensis SQR9, B. velezensis GS-1, and B. amyloliquefaciens DSM7) revealed that the strains had a part common coding sequences (CDS) in whereas 42 coding were unique of strain YC89. Whole-genome sequencing revealed 547 carbohydrate-active enzymes and identified 12 gene clusters encoding secondary metabolites. Additionally, functional analysis of the genome revealed numerous gene/gene clusters involved in plant growth promotion, antibiotic resistance, and resistance inducer synthesis. In vitro pot tests indicated that YC89 strain controlled sugarcane red rot and promoted the growth of sugarcane plants. Additionally, it increased the activity of enzymes involved in plant defense, such as superoxide dismutase, peroxidase, polyphenol oxidase, chitinase, and ß-1,3-glucanase. Discussion: These findings will be helpful for further studies on the mechanisms of plant growth promotion and biocontrol by B. velezensis and provide an effective strategy for controlling red rot in sugarcane plants.

A red ambient afterglow material with lifetime of 0.5 s and efficiency over 12.

γCbPhAP, a D-A dyad with γ-carboline as the D unit and 3-phenylacenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile as the A moiety and phosphorescence core, was designed and synthesized. The doping system of 1 wt% γCbPhAP in PMMA shows red ambient phosphorescence-dominated afterglow with long lifetime of 0.5 s and decent efficiency over 12%.

A Low-Cost Test Method for Accurate Detection of Different Excited-State Species with a Lifetime Span over 5 Orders of Magnitude in One Time Window.

Accurate quantification on the quantum yields (φ) of both the prompt fluorescence (PF) and the delayed fluorescence (DF) species is quite essential for the clarification of molecular design rationales for thermally activated delayed fluorescence (TADF) luminogens. Currently, most φPF and φDF data of TADF fluorophores were acquired through time-correlated single-photon counting (TCSPC) lifetime measurement systems. However, because of their equal-time-channel working manner, so far all the commercially available TCSPC systems cannot render accurate measurement on φPF of TADF materials due to the lack of enough valid data points in the faster decay region of the corresponding photoluminescence (PL) decay curves. Although an intensified charge coupled device (ICCD) system equipped with a streak camera or an optical parametric oscillation laser has been proven to be a powerful tool for accurate determination of φPF and φDF of TADF fluorophores, the ultrahigh cost of these ICCD systems makes them inaccessible to most users. Herein, by replacing the timing module of a commercial TCSPC system with a low-cost and versatile time-to-digital converter (TDC) module, we developed a modified TCSPC system that can work in an unequal-time-channel manner. The resultant TDC-TCSPC system can not only concurrently determine the accurate lifetime of PF and DF species whose lifetime span even exceeds 5 orders of magnitude in just one time window but also render accurate measurements on φPF and φDF of TADF fluorophores. The reliability of the TDC-TCSPC method was verified through TCSPC- and ICCD-based comparative experiments on ACMPS, a known TADF fluorophore. Our results not only can provide a low-cost and convenient test method for accurate determination of key experimental data of TADF materials but also will facilitate deeper understanding of the molecular design principles for high-performance TADF materials.

Ultra-fast triplet-triplet-annihilation-mediated high-lying reverse intersystem crossing triggered by participation of nπ*-featured excited states.

The harvesting of 'hot' triplet excitons through high-lying reverse intersystem crossing mechanism has emerged as a hot research issue in the field of organic light-emitting diodes. However, if high-lying reverse intersystem crossing materials lack the capability to convert 'cold' T1 excitons into singlet ones, the actual maximum exciton utilization efficiency would generally deviate from 100%. Herein, through comparative studies on two naphthalimide-based compounds CzNI and TPANI, we revealed that the 'cold' T1 excitons in high-lying reverse intersystem crossing materials can be utilized effectively through the triplet-triplet annihilation-mediated high-lying reverse intersystem crossing process if they possess certain triplet-triplet upconversion capability. Especially, quite effective triplet-triplet annihilation-mediated high-lying reverse intersystem crossing can be triggered by endowing the high-lying reverse intersystem crossing process with a 3ππ*→1nπ* character. By taking advantage of the permanent orthogonal orbital transition effect of 3ππ*→1nπ*, spin-orbit coupling matrix elements of ca. 10 cm-1 can be acquired, and hence ultra-fast mediated high-lying reverse intersystem crossing process with rate constant over 109 s-1 can be realized.

A water-soluble sensor for distinguishing D2O from H2O by dual-channel absorption/fluorescence ratiometry.

By taking advantage of the slight difference in the acidity of D2O and H2O, we report a novel D2O optical sensor, namely Cy, with integrated great water-solubility, absorption/fluorescence dual-channel ratiometric response and even RGB visual sensing application. This work puts forward a facile method for distinguishing D2O from H2O with high sensitivity and high accuracy.

Visualizing Lysosomal Positioning with a Fluorescent Probe Reveals a New Synergistic Anticancer Effect.

The observation and discovery of lysosome dynamic alterations will greatly contribute to the in-depth understanding of lysosome biology and the development of new cancer therapeutics. To visualize lysosomal dynamics, here we have developed a lysosome-targetable fluorescent probe of NIM-3 showing integrated high selectivity, high photostability, and low cytotoxicity. With the aid of the excellent spatial and temporal imaging capability of NIM-3, three different types of motion of lysosomes were defined, and perinuclear accumulation of lysosomes in response to the pro-inflammatory cytokine stimulus was observed in various cells. More importantly, through lysosomal positioning studies, a new and potential anticancer therapy, i.e., the combination treatment of TNFα (tumor necrosis factor alpha) and chloroquine (CQ, a lysosomal pH elevator), was disclosed. The efficacy of the "CQ + TNFα" treatment was verified by different types of human cancer cells, and the anticancer mechanism may be partially attributed to lysosomal dilation.

In situ optical spectroscopy for monitoring plasma-assisted formation of lanthanide metal-organic frameworks.

A novel system was designed, which integrated in situ spectral monitoring with facile synthesis of lanthanide metal-organic frameworks in dielectric barrier discharge (DBD) plasma. It features miniaturization, cost-effectiveness and universality, for in situ spectral information of scattering and luminescence to gain insight into the reactive processes.

Analysis of the Isotopic Purity of D2O with the Characteristic NIR-II Phosphorescence of Singlet Oxygen from a Photostable Polythiophene Photosensitizer.

D2O plays important roles in a variety of fields (such as the nuclear industry and bioorganic analysis), and thus its isotopic purity (H2O contents) is highly concerned. Due to its highly similar physical properties to H2O and large excess amounts of H2O over D2O, it is challenging to distinguish D2O from H2O. On the basis of the characteristic NIR-II phosphorescence of singlet oxygen (1O2), and the fact that H2O is a more efficient quencher for 1O2 than D2O, here, we proposed to simply use the 1275 nm emission of 1O2 for the analysis of the isotopic purity of D2O. In normal cases (a xenon lamp for excitation), such steady-state emission is extremely weak for valid analytical applications, we thus employed laser excitation for intensification. To this goal, a series of photosensitizers were screened, and eventually polythiophene PT10 was selected with high singlet oxygen quantum yield (ΦΔ = 0.51), high H2O/D2O contrast, and excellent photostability. Upon excitation with a 445 nm laser, a limit of detection (LOD, 3σ) of 0.1% for H2O in D2O was achieved. The accuracy of the proposed method was verified by the analysis of the isotopic purity of several D2O samples (with randomly added H2O). More interestingly, the hygroscopicity of D2O was sensitively monitored with the proposed probe in a real-time manner; the results of which are important for strengthening the care of D2O storage and the importance of humidity control during related investigations. Besides D2O isotopic purity evaluation, this work also indicated the potential usefulness of the NIR-II emission of singlet oxygen in future analytical detection.

An Ultraviolet Thermally Activated Delayed Fluorescence OLED with Total External Quantum Efficiency over 9.

Owing to the difficulty in acquiring compounds with combined high energy bandgaps and lower-lying intramolecular charge-transfer excited states, the development of ultraviolet (UV) thermally activated delayed fluorescence (TADF) materials is quite challenging. Herein, through interlocking of the diphenylsulfone (PS) acceptor unit of a reported deep-blue TADF emitter (CZ-PS) by a dimethylmethylene bridge, CZ-MPS, a UV-emissive TADF compound bearing a shallower LUMO energy level and a more rigid structure than those of CZ-PS is achieved. This represents the first example of a UV-emissive TADF compound. Organic light-emitting diode (OLED) using CZ-MPS as the guest material can emit efficient UV light with emission maximum of 389 nm and maximum total external quantum efficiency (EQEmax ) of 9.3%. Note that this EQEmax value is twice as high as the current record EQEmax (4.6%) for UV-OLEDs. This finding may shed light on the molecular design strategy for high-performance UV-OLED materials.

A Facile Strategy for the Construction of Purely Organic Optical Sensors Capable of Distinguishing D2 O from H2 O.

Owing to the quite similar chemical properties of H2 O and D2 O, rational molecular design of D2 O optical sensors has not been realized so far. Now purely organic chromophores bearing OH groups with appropriate pKa values are shown to display distinctly different optical responding properties toward D2 O and H2 O owing to the slight difference in acidity between D2 O and H2 O. This discovery is a new and facile strategy for the construction of D2 O optical sensors. Through this strategy, ratiometric colorimetric D2 O sensor of NIM-2F and colorimetric/fluorescent dual-channel D2 O sensor of AF were acquired successfully. Both NIM-2F and AF can not only qualitatively distinguish D2 O from H2 O by the naked eye, but also quantitatively detect the H2 O content in D2 O.

Facile Access to Twisted Intramolecular Charge-Transfer Fluorogens Bearing Highly Pretwisted Donor-Acceptor Systems Together with Readily Fine-Tuned Charge-Transfer Characters.

Twisted intramolecular charge-transfer (TICT) fluorogens bearing highly pretwisted geometries and readily-fine-tuned charge-transfer characters are quite promising sensor and electroluminescence (EL) materials. In this study, by using 4-aryloxy-1,8-naphthalimide derivatives as the molecular framework, it is demonstrated for the first time that a CO bond could serve as the central bond to construct new TICT D-A systems. Photophysical and quantum chemical studies confirm that rotation around central CO bonds is responsible for the formation of a stable TICT state in these compounds. More importantly, owing to the structural adjustability of the aryl moiety and the strong steric interactions between the naphthalimide and the aryl ring systems, these compounds can display readily-fine-tuned TICT characters, hence exhibiting an adjustable solvent polarity threshold for aggregation-induced emission (AIE) activity, and could be AIE-active even in less-polar toluene and nonpolar cyclohexane. Furthermore, these compounds could possess highly-pretwisted ground-state geometries, hence could show good EL performance. The findings reveal a facile but effective molecular constructive strategy for versatile, high-performance optoelectronic TICT compounds.