Microglia and Astrocytes Responses Contribute to Alleviating Inflammatory Damage by Repetitive Transcranial Magnetic Stimulation in Rats with Traumatic Brain Injury.

Repetitive transcranial magnetic stimulation (rTMS) is a therapeutic strategy that shows promise in ameliorating the clinical sequelae following traumatic brain injury (TBI). These improvements are associated with neuroplastic changes in neurons and their synaptic connections. However, it has been hypothesized that rTMS may also modulate microglia and astrocytes, potentially potentiating their neuroprotective capabilities. This study aims to investigate the effects of high-frequency rTMS on microglia and astrocytes that may contribute to its neuroprotective effects. Feeney's weight-dropping method was used to establish rat models of moderate TBI. To evaluate the neuroprotective effect of high frequency rTMS on rats by observing the synaptic ultrastructure and the level of neuron apoptosis. The levels of several important inflammation-related proteins within microglia and astrocytes were assessed through immunofluorescence staining and western blot. Our findings demonstrate that injured neurons can be rescued through the modulation of microglia and astrocytes by rTMS. This modulation plays a key role in preserving the synaptic ultrastructure and inhibiting neuronal apoptosis. Among microglia, we observed that rTMS inhibited the levels of proinflammatory factors (CD16, IL-6 and TNF-α) and promoted the levels of anti-inflammatory factors (CD206, IL-10 and TNF-ß). rTMS also reduced the levels of pyroptosis within microglia and pyroptosis-related proteins (NLRP3, Caspase-1, GSDMD, IL-1ß and IL-18). Moreover, rTMS downregulated P75NTR expression and up-regulated IL33 expression in astrocytes. These findings suggest that regulation of microglia and astrocytes is the mechanism through which rTMS attenuates neuronal inflammatory damage after moderate TBI.

Hydrostatic pressure effect on excited state properties of room temperature phosphorescence molecules: A QM/MM study.

Stimulus-responsive organic room temperature phosphorescence (RTP) materials exhibit variations in their luminescent characteristics (lifetime and efficiency) upon exposure to external stimuli, including force, heat, light and acid-base conditions, the development of stimulus-responsive RTP molecules becomes imperative. However, the inner responsive mechanism is unclear, theoretical investigations to reveal the relationship among hydrostatic pressures, molecular structures and photophysical properties are highly desired. Herein, taking the Se-containing RTP molecule (SeAN) as a model, based on the dispersion corrected density functional theory (DFT-D), the combined quantum mechanics and molecular dynamics (QM/MM) method and thermal vibration correlation function (TVCF) theory, the influences of hydrostatic pressure on molecular structures, transition properties as well as lifetimes and efficiencies of RTP molecule are theoretically studied. Results show that extended lifetime and enhanced efficiency are observed at 2 Gpa compared with molecule at normal pressure, and this is related with the small reorganization energy and large oscillator strength. Moreover, due to the small energy gap (0.34 eV) and remarkable spin-orbit coupling (SOC) constant (8.56 cm-1) between first singlet excited state and triplet state, fast intersystem crossing (ISC) process is determined for molecule at 6 Gpa. Furthermore, the intermolecular interactions are visualized using independent gradient model based on Hirshfeld partition (IGMH) and the changes of molecular packing modes, SOC values, lifetimes and efficiencies with pressures are detected. These results reveal the relationship between molecular structures and RTP properties. Our work provides theoretical insights into the hydrostatic pressure response mechanism and could promote the development new efficient stimulus-responsive molecules.

Theoretical insights on highly efficient X-shaped near-infrared thermal activation delayed fluorescence emitter.

The near-infrared (NIR) thermally activated delayed fluorescence (TADF) molecules hold practical application value in various fields, including biological imaging, anti-counterfeiting, sensors, telemedicine, photomicrography, and night vision display. These molecules have emerged as a significant development direction in organic electroluminescent devices, offering exciting possibilities for future technological advancements. Despite the remarkable potential of NIR-TADF molecules in various applications, the development of molecules that exhibit both long-wavelength emission and high efficiency remains a significant challenge. Herein, based on T-type and Y-type TADF molecules BCN-TPA and ECN-TPA, a novel X-type TADF molecule X-ECN-TPA is theoretically designed through a molecular fusion strategy. Utilizing first-principles calculations and the thermal vibration correlation function (TVCF) method, the photophysical properties and luminescent mechanisms of these three molecules in both solvent and solid (doped films) are revealed. A comparison of the luminescent properties of isomeric BCN-TPA and ECN-TPA shows that the enhanced luminescence efficiency of BCN-TPA in the solid states is attributed to higher radiative rates and lower non-radiative rates. Furthermore, compared to BCN-TPA and ECN-TPA, X-ECN-TPA exhibits significant conjugation extension, resulting in a pronounced redshift, reaching 831 nm and 813 nm in solvent and solid states, respectively. Importantly, molecular fusion significantly increases the transition dipole moment density between the donor and acceptor, leading to a substantial increase in radiative transition rates. Additionally, molecular fusion effectively reduces the energy gap between the first singlet excited state (S1) and the first triplet excited state (T1), facilitating the improvement of the reverse intersystem crossing (RISC) process. In addition, the calculation of Marcus formula shows that the triplet energy transfer from CBP to BCN-TPA, ECN-TPA and X-ECN-TPA is very effective. This work not only designs a novel efficient NIR-TADF molecule but also proposes a strategy for designing efficient NIR-TADF molecules. This principle offers unique insights for optimizing traditional molecular frameworks, opening up new possibilities for future advancements.

Dissemination of Ceftriaxone-Resistant Salmonella Enteritidis Harboring Plasmids Encoding blaCTX-M-55 or blaCTX-M-14 Gene in China.

Salmonella Enteritidis was the primary foodborne pathogen responsible for acute gastroenteritis. The growing ceftriaxone resistance poses a significant threat to public health. Infection with S. Enteritidis has emerged as a major public health concern, particularly in developing countries. However, research on ceftriaxone-resistant S. Enteritidis (CRO-RSE) remains limited, particularly concerning its resistance mechanism, plasmid structure, and transmission characteristics. This study aims to address these gaps comprehensively. We collected 235 S. Enteritidis isolates from Hangzhou First People's Hospital between 2010 and 2020. Among these, 8.51% (20/235) exhibited resistance to ceftriaxone. Whole-genome analysis revealed that 20 CRO-RSE isolates harbored blaCTX-M-55 or blaCTX-M-14 on the plasmid. Moreover, the dissemination of the blaCTX-M-type gene was associated with IS26 and ISEcp1. Plasmid fusion entailing the integration of the p1 plasmid with antibiotic resistance genes and the p2 (pSEV) virulence plasmid was observed in certain CRO-RSE. Additionally, the structural analysis of the plasmids unveiled two types carrying the blaCTX-M-type gene: type A with multiple replicons and type B with IncI1 (Alpha) replicon. Type B plasmids exhibited superior adaptability and stability compared to type A plasmids within Enterobacteriaceae. Interestingly, although the type B (S808-p1) plasmid displayed the potential to spread to Acinetobacter baumannii, it failed to maintain stability in this species.

Theoretical Insights into the Photophysical Properties of 4CzIPN Doped in Different Hosts: A Multiscale Study.

As a typical thermally activated delayed fluorescence (TADF) emitter with green emission, 4CzIPN has attracted much attention recently. Most studies indicated that 4CzIPN doped in different hosts presented different performances; thus, the hosts should have an obvious influence on its photophysical properties. Herein, the influence of four kinds of hosts, including m-CzPym, m-CzTrz, p-CzPym, and p-CzTrz, on the photophysical properties of 4CzIPN is investigated. Molecular dynamics simulations were performed to simulate the host-guest conformations, and the photophysical properties were studied using the combined quantum mechanics/molecular mechanics method coupled with the thermal-vibration correlation function method. It is found that 4CzIPN in doped films has larger transition dipole moments and spin-orbital coupling constants compared to that in nondoped films. Faster radiative decay, intersystem crossing rates, and higher fluorescence efficiency could be obtained in doped films. Our work helps to better understand the photophysical properties of 4CzIPN in doped films and may favor the design of new hosts.

Quasi-intrinsic thiobase derivatives as potential targeted photosensitizers in two-photon photodynamic therapy.

In this study, a set of potential quasi-intrinsic photosensitizers for two-photon photodynamic therapy (PDT) are proposed based on the unnatural 2-amino-8-(1'-ß-ᴅ-2'-deoxyribofuranosyl)-imidazo[1,2-ɑ]-1,3,5-triazin-4(8H)-one (P), which is paired with the 6-amino-5-nitro-3-(1'-ß-ᴅ-2'-deoxyribofuranosyl)-2(1H)-pyridone (Z) and can specifically recognize breast and liver cancer cells. Herein, the effects of sulfur substitution and electron-donating/electron-withdrawing groups on the photophysical properties in aqueous solution are systematically investigated. The one- and two-photon absorption spectra evidence that the modifications could result in red-shifted absorption wavelength and large two-photon absorption cross-section, which contributes to selective excitation and provides effective PDT for deep-seated tissues. To ensure the efficient triplet state population, the singlet-triplet energy gaps and spin-orbit coupling constants were examined, which is responsible for a rapid intersystem crossing rate. Furthermore, these thiobase derivatives are characterized by the long-lived T1 state and the large energy gap for radiationless transition to ensure the generation of cytotoxic singlet oxygen.

Role of Bridging Groups in Regulating the Luminescence and Charge Transfer Properties of Thermally Activated Delayed Fluorescence Molecules: A Theoretical Perspective.

Organic emitters with a simultaneous combination of aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF) characteristics are in great demand due to their excellent comprehensive performances toward efficient organic light-emitting diodes (OLEDs), biomedical imaging, and the telecommunications field. However, the development of efficient AIE-TADF materials remains a substantial challenge. In this work, light-emitting properties of two AIE-TADF molecules with different bridging groups ICz-BP and ICz-DPS are theoretically investigated in the solid state with the combined quantum mechanics/molecular mechanics (QM/MM) method and the thermal vibration correlation function (TVCF) theory. The research indicates that the C═O bridging bond in ICz-BP is more favorable than the S═O bridging bond in ICz-DPS for enhancing the planarity of the acceptor, increasing conjugation, and thereby elevating the transition dipole moment density. Simultaneously, the stacking pattern of ICz-BP in the solid facilitates a reduction in energy gap between S1 and T1 (ΔEST), achieving rapid reverse intersystem crossing rate (kRISC). Furthermore, compared to toluene, the stacking patterns of ICz-BP and ICz-DPS in the solid effectively suppress the out-of-plane wagging vibration of the acceptor, thereby inhibiting the loss of nonradiative energy in the excited state and realizing aggregation-induced emission. Moreover, the charge transport properties of both electrons and holes in ICz-BP are found to be higher than the corresponding rates in ICz-DPS, attributed to the smaller internal reorganization energy of ICz-BP in the solid state. Additionally, the calculations reveal a more balanced charge transport characteristic in ICz-BP, contributing to efficient exciton recombination and emission and ultimately mitigating efficiency roll-off. Based on these computational results, we aim to unveil the relationship between molecular structure and light-emitting properties, aiding in the design and development of efficient AIE-TADF devices.

Modulation of luminescence properties of circularly polarized thermally activated delayed fluorescence molecules with axial chirality by donor engineering.

Multifunctional thermally activated delayed fluorescence (TADF) materials are currently a trending research subject for luminescence layer materials of organic light-emitting diodes (OLEDs). Among these, circularly polarized thermally activated delayed fluorescence (CP-TADF) materials have the advantage of being able to directly achieve highly efficient circularly polarized luminescence (CPL). The simultaneous integration of outstanding luminescence efficiency and excellent luminescence asymmetry factor (glum) is a major constraint for the development of CP-TADF materials. Therefore, on the basis of first-principles calculations in conjunction with the thermal vibration correlation function (TVCF) method, we study CP-TADF molecules with different donors to explore the feasibility of using the donor substitution strategy for optimizing the CPL and TADF properties. The results indicate that molecules with the phenothiazine (PTZ) unit as the donor possess small energy difference, a great spin-orbit coupling constant and a rapid reverse intersystem crossing rate, which endow them with remarkable TADF features. Meanwhile, compared with the reported molecules, the three designed molecules exhibit better CPL properties with higher glum values. Effective molecular design strategies by donor engineering to modulate the CPL and TADF properties are theoretically proposed. Our findings reveal the relationship between molecular structures and luminescence properties of CP-TADF molecules and further provide theoretical design strategies for optimizing the CPL and TADF properties.

Conformational Isomerization Effect on Singlet/Triplet Energy Consumption Process of Thermally Activated Delayed Fluorescence Molecules with Aggregation Induced Emission: A QM/MM Study.

Thermally activated delayed fluorescence (TADF) molecules with aggregation-induced emission (AIE) properties hold tremendous potential in biomedical sensing/imaging and telecommunications. In this study, a multiscale method combined with thermal vibration correlation function (TVCF) theory is used to investigate the photophysical properties of the novel TADF molecule CNPy-SPAC in toluene and crystal and amorphous states. In the crystal state, an increase in radiative rates and a decrease in nonradiative rates lead to AIE. Additionally, conformational isomerization effects result in significantly different luminescent efficiencies between the two crystal structures. Furthermore, the isomerization effect allows for the coexistence of three configurations in the amorphous state. Among them, the non-TADF quasi-axial (Qa) configuration may facilitate energy transfer to the TADF-characteristic quasi-equal/quasi-equal-H (Qe/Qe-H) configurations, enhancing AIE. Moreover, the Qa configuration enables rapid electron transport, offering the potential for self-doped devices. Our work elucidates a new mechanism for the isomerization effect in AIE-TADF molecules.

Theoretical design and performance prediction of deep red/near-infrared thermally activated delayed fluorescence molecules with through space charge transfer.

Thermally activated delayed fluorescence (TADF) molecules with through-space charge transfer (TSCT) have attracted much attention in recent years because of their ability to simultaneously reduce the energy difference (ΔEST) and enlarge the spin-orbit coupling (SOC). In this paper, 40 molecules are theoretically designed by changing the different substitution positions of the donors and acceptors, and systematically investigated based on the first-principles calculations and excited-state dynamics study. It is found that the emission wavelengths of v-shaped molecules with intramolecular TSCT are larger than those of the molecules without TSCT. Therefore, the intramolecular TSCT can induce the red-shift of the emission and realize the deep-red/near-infrared emission. Besides intramolecular TSCT can simultaneously increase the SOC as well as the oscillator strength and reduce the ΔEST. In addition, PXZ or PTZ can also favor the realization of smaller ΔEST and red-shift emission. Our calculations suggest that intramolecular TSCT and suitable donors (-PXZ or -PTZ) are an effective strategy for the design of efficient deep red/near-infrared TADF emitters.

A molecular descriptor of a shallow potential energy surface for the ground state to achieve narrowband thermally activated delayed fluorescence emission.

Narrowband thermally activated delayed fluorescence (TADF) molecules have extensive applications in optoelectronics, biomedicine, and energy. The full-width at half-maximum (FWHM) holds significant importance in assessing the luminescence efficiency and color purity of TADF molecules. The goal is to achieve efficient and stable TADF emissions by regulating and optimizing the FWHM. However, a bridge from the basic physical parameters (such as geometric structure and reorganization energy) to the macroscopic properties (delayed fluorescence, efficiency, and color purity) is needed and it is highly necessary and urgent to explore the internal mechanisms that influence FWHM. Herein, first-principles calculations coupled with the thermal vibration correlation function (TVCF) theory were performed to study the energy consumption processes of the excited states for the three TADF molecules (2,3-POA, 2,3-DPA, and 2,3-CZ) with different donors; inner physical parameters affecting the FWHM were detected. By analyzing the basic geometric and electronic structures as well as the transition properties and reorganization energies, three main findings in modulating FWHM were obtained, namely a large local excitation (LE) proportion in the first singlet excited state is advantageous in reducing FWHM, a donor group with weak electron-donating ability is beneficial for achieving narrowband emission, and small reorganization energies for the ground state are favorable for reducing FWHM. Thus, wise molecular design strategies to achieve efficient narrowband TADF emission are theoretically proven and proposed. We hope that these results will promote an in-depth understanding of FWHM and accelerate the development of high color purity TADF emitters.

Theoretical study on the influence of substitution position on the luminescence properties and charge transfer characteristics of thermally activated delayed fluorescent molecules.

Thermally active delayed fluorescence (TADF) molecules have potentially applications in organic light-emitting diodes (OLEDs) and biomedical sensing. Although TADF emitters have witnessed a rapid development, it remains challenging to study the relationship between molecular structures and luminescence properties as well as carrier mobility transfer properties in theory. In this work, the photophysical properties and luminescence mechanisms of isomers TPA-APQDCN-C (donors at para-position) and TPA-APQDCN-Y (donors at ortho-position) were studied based on density functional theory (DFT) and thermal vibration correlation function (TVCF) method. The results showed that both TPA-APQDCN-C with para-substituted donor and TPA-APQDCN-Y with ortho-substituted donors exhibit red emission in toluene and crystal state. Furthermore, compared to ortho-substituted donors, para-substituted donors promote a redshift in emission wavelength. In addition, the fluorescence efficiencies of TPA-APQDCN-C is obviously higher than that of TPA-APQDCN-Y due to its larger radiative rate and less non-radiative decay rate. Besides, para-substitution (TPA-APQDCN-C) leads to the smaller energy gap between S1 and T1 and the larger spin-orbit coupling (SOC) constant, which is beneficial for increasing the reverse crossing intersystem (RISC) rates. In addition, the carrier mobilities are studied based on the kinetic Monte Carlo simulations. The calculations show that TPA-APQDCN-C are more beneficial for the transfer of holes compared to TPA-APQDCN-Y. This study reveals TPA-APQDCN-C with donors at para-position has a better TADF properties and hole transfer ability, which holds guiding significance for the design of TADF devices with high luminescence efficiency and rapid hole transfer.

Modulating excited state properties of thermally activated delayed fluorescence molecules by hybrid long-range and short-range charge transfer strategy.

Balancing the rapid radiative decay process and the fast reverse intersystem crossing (RISC) process of thermally activated delayed fluorescence (TADF) molecule remains a great challenge and efficient molecular design strategies are highly desired. Herein, from a theoretical perspective, excited state properties of three reported TADF molecules (1TICz, 1BOICz and 2BOICz) are investigated based on density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations coupled with the thermal vibration correlation function (TVCF) method. Results indicate that, by introducing the multi-resonance (MR) acceptor, 1BOICz possesses hybrid long-range and short-range charge transfer features, balanced small energy gap (ΔEST) and large oscillator strength (f) is obtained. Furthermore, by incorporating double equivalent MR acceptors in 2BOICz, largely enhanced f with slightly changed ΔEST is achieved, inner mechanism for remarkable photophysical property is illustrated. Keep this strategy, seven new TADF molecules (2pDBA-bICz-1, 2pDBA-bICz-2, 2OSBA-bICz, 2DQAO-bICz, 2QAO-bICz, 2SQAO-bICz and 2OQAO-bICz) are theoretically designed, detailed physical parameters are analyzed and excited state energy consumption process is studied. Strong electrophilicity on acceptor is determined and the strength of nucleophilic sites on the bridge-phenyl of 2DQAO-bICz, 2QAO-bICz, 2SQAO-bICz and 2OQAO-bICz is increased, this promotes the short-range charge transfer property. In addition, the excitation processes for all studied molecules are dominated by long-range charge transfer from donor to acceptors, and supplemented by the short-range charge transfer on the bridge-phenyl with MR effect. Compromise energy gap and oscillator strength as well as large spin orbit coupling (SOC) constant are obtained for designed molecules. Thus, by regulating the long-range and short-range charge transfer ratios, excited state properties are successfully modulated and new efficient TADF molecules are proposed. Our research aims to provide deeper insight into long-range and short-range charge transfer features in balancing small ΔEST and large f, which could facilitate the development of novel efficient TADF molecules.

Hot Deformation Behavior and Mechanisms of SiC Particle Reinforced Al-Zn-Mg-Cu Alloy Matrix Composites.

A systematic and comprehensive analysis of the hot deformation and mechanisms of SiC particle-reinforced aluminum matrix composites is significant for optimizing the processing of the composites and obtaining the desired components. Based on this, related research on 11 vol% SiCp particle-reinforced 7050Al matrix composites was carried out. Hot compression experiments were carried out on the Gleeble-3500 thermal simulator to study the hot deformation behavior of composites at the temperature of 370-520 °C and strain rate of 0.001-10 s-1. The hyperbolic sine constitutive equation of the material was established, and the processing map was calculated. Combining the typical metallograph and misorientation angle distribution, the microstructure evolution mechanism of composites was analyzed, and the effect of particles on recrystallization behavior was investigated. Under certain process conditions, the dominant deformation mechanism of composites changed from dynamic recovery (DRV) to dynamic recrystallization (DRX), and the grain boundary sliding mechanism began to play a role. In addition, high temperature tensile and elongation at break were tested, and it was found that the dominant form of fracture failure changed from brittle fracture of the particles to ductile fracture of the matrix as the temperature increased.

Single-Component Color-Tunable Smart Organic Emitters with Simultaneous Multistage Stimuli-Responsiveness and Multimode Emissions.

Achieving color-tunable emission in single-component organic emitters with multistage stimuli-responsiveness is of vital significance for intelligent optoelectronic applications, but remains enormously challenging. Herein, we present an unprecedented example of a color-tunable single-component smart organic emitter (DDOP) that simultaneously exhibits multistage stimuli-responsiveness and multimode emissions. DDOP based on a highly twisted amide-bridged donor-acceptor-donor structure has been found to facilitate intersystem crossing, form multimode emissions, and generate multiple emissive species with multistage stimuli-responsiveness. DDOP pristine crystalline powders exhibit abnormal excitation-dependent emissions from a monomer-dominated blue emission centered at 470 nm to a dimer-dominated yellow emission centered at 550 nm through decreasing the ultraviolet (UV) excitation wavelengths, whereas DDOP single crystals show a wide emission band with a main emission peak at 585 nm when excited at different wavelengths. The emission behaviors of pristine crystalline powders and single crystals are different, demonstrating emission features that are closely related to the aggregation states. The work has developed color-tunable single-component organic emitters with simultaneous multistage stimuli-responsiveness and multimode emissions, which is vital for expanding intelligent optoelectronic applications, including multilevel information encryption, multicolor emissive patterns, and visual monitoring of UV wavelengths.

Organic Bilayer Heterostructures with Built-In Exciton Conversion for 2D Photonic Encryption.

Organic multilayer heterostructures with accurate spatial organization demonstrate strong light-matter interaction from excitonic responses and efficient carrier transfer across heterojunction interfaces, which are considered as promising candidates toward advanced optoelectronics. However, the precise regulation of the heterojunction surface area for finely adjusting exciton conversion and energy transfer is still formidable. Herein, organic bilayer heterostructures (OBHs) with controlled face-to-face heterojunction via a stepwise seeded growth strategy, which is favorable for efficient exciton propagation and conversion of optical interconnects are designed and synthesized. Notably, the relative position and overlap length ratio of component microwires (LDSA /LBPEA = 0.39-1.15) in OBHs are accurately regulated by modulating the crystallization time of seeded crystals, resulting into a tailored heterojunction surface area (R = Loverlap /LBPEA = 37.6%-65.3%). These as-prepared OBHs present the excitation position-dependent waveguide behaviors for optical outcoupling characteristics with tunable emission colors and intensities, which are applied into two-dimensional (2D) photonic barcodes. This strategy opens a versatile avenue to purposely design OBHs with tailored heterojunctions for efficient energy transfer and exciton conversion, facilitating the application possibilities of advanced integrated optoelectronics.

A Case of Primary Esophageal Sarcomatoid Carcinoma Detected by 18F-FDG PET/CT.

ABSTRACT: Primary sarcomatoid carcinoma of the esophagus is a rare and highly malignant neoplasm with a poor prognosis. A 51-year-old man presented with difficulty in swallowing for 2 weeks. Thoracic CT revealed a huge mass in the middle-lower thoracic esophagus. 18F-FDG PET/CT showed intense 18F-FDG uptake of the esophageal tumor. Histopathology and immunohistochemistry of the esophageal lesion tissue confirmed the diagnosis of sarcomatoid carcinoma after postoperative pathological biopsy.

Multi-resonance thermally activated delayed fluorescence molecules with intramolecular-lock: theoretical design and performance prediction.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) molecules with narrow full width at half maximum (FWHM) have attracted much attention recently. In this work, 36 borane/amine (B/N) type MR-TADF molecules were theoretically designed by using an intramolecular-lock strategy and systematically studied based on first-principles calculations. It was found that intramolecular-lock at different positions and in different manners could induce different luminescent properties. The calculated oscillator strengths for PXZ-L2 and PTZ-L2 locking systems are weaker than that for 2DPABN (without intramolecular-lock), while the Cz-L1 and TMCZ-L1 locking could result in stronger oscillator strength. Though the calculated FWHM of all the systems with intramolecular-lock is higher than that of 2DPABN, the Cz, TMCz and DMAC locking at L1 or L2 would induce relatively small FWHM which is comparable to that of 2DPABN. Our calculation results indicate that intramolecular-lock could enhance the SOC values and decrease the energy gap between the first singlet excited state and the first triplet excited state, which is quite favorable to reverse intersystem crossing. The Cz, TMCz and DMAC locking systems could realize comparable and higher efficiency than 2DPABN, thus higher quantum efficiency could be obtained. Our calculation results indicate that the intramolecular-lock strategy is an effective method to realize the design of highly efficient MR-TADF emitters.

Theoretical exploration of the bromine substitution effect and hydrostatic pressure responsive mechanism for room temperature phosphorescence.

Stimulus-responsive organic room temperature phosphorescence (RTP) materials with long lifetimes, high efficiencies and tunable emission properties have broad applications. However, the amounts and species of efficient RTP materials are far from meeting the requirements and the inner stimulus-responsive mechanisms are unclear. Therefore, developing efficient stimulus-responsive RTP materials is highly desired and the relationship between the molecular structures and luminescent properties of RTP materials needs to be clarified. Based on this point, the influences of different substitution sites of Br on the luminescent properties of RTP molecules are studied by the combined quantum mechanics and molecular mechanics (QM/MM) coupled with thermal vibration correlation function (TVCF) theory. Moreover, the hydrostatic pressure effect on the efficiencies and lifetimes is explored and the inner mechanism is illustrated. The results show that, for the exciton conversion process, the o-substitution molecule possesses the largest spin-orbit coupling (SOC) value (〈S1|Hso|T1〉) in the intersystem crossing (ISC) process and this is conducive to the accumulation of triplet excitons. However, for the energy consumption process, the large SOC value (〈S0|Hso|T1〉) for the p-substitution molecule brings a fast non-radiative decay rate, and the small SOC value for the m-substitution molecule generates a decreased non-radiative decay rate which is helpful for realizing long lifetime emission. Keeping with this perspective, the conflict between high exciton utilization and long RTP emission needs to be balanced rather than enhancing the SOC effect by simply adding heavy atoms in RTP systems. Through regulating the molecular stacking modes by the hydrostatic pressure effect, the inner stimulus-responsive mechanism is revealed. The data of 〈S1|Hso|T1〉 in the ISC process remain almost unchanged, while 〈S0|Hso|T1〉 values and transition dipole moments are sensitive to the hydrostatic pressure. Under 1 GPa, the RTP molecule achieves a maximum efficiency (81.17%) and long lifetime (2.72 ms) with the smallest SOC and decreased non-radiative decay rate. To our knowledge, this is the first time that the hydrostatic pressure responsive mechanism for RTP molecules is revealed from a theoretical perspective, and the relationships between molecular structures and luminescent properties are detected. Our work could facilitate the development of high performance RTP molecules and expand their applications in multilevel information encryption.

Three-Dimensional Macroporous rGO-Aerogel-Based Composite Phase-Change Materials with High Thermal Storage Capacity and Enhanced Thermal Conductivity.

Three-dimensional porous network encapsulation strategy is an effective means to obtain composite phase-change materials (PCMs) with high heat storage capacity and enhanced thermal conductivity. Herein, macroporous reduced graphene oxide (rGO) aerogels with adjustable pore size are prepared by the emulsion template method and hydrothermal reduction process. Further, the shape-stabilized rGO-aerogel-based composite PCMs are constructed after the combination of 3D porous rGO supports and paraffin wax (PW) through vacuum melting infiltration. By regulating the pore structure of the rGO aerogel network, the rGO-based composite PCMs achieve excellent energy storage properties with a phase-change enthalpy of 179.94 J/g for the loading amount of 95.61 wt% and an obvious enhancement in thermal conductivity of 0.412 W/m-1·K-1, which is 54.89% higher than pristine PW and enduring thermal cycling stability. The obtained macroporous rGO-aerogel-based composite PCMs with high thermal storage and heat transfer performance effectively broaden the application of PCMs in the field of thermal energy storage.