Molecular Design Approach Research Articles

On Identifying Crossover Induced Self-Discharge of Non-Aqueous Redox-Flow Batteries and Ketazin Based Redox-Active Species

Redox flow batteries (RFB) are a promising technology for storing electrical energy in the grid because of their high scalability, design flexibility, long-term efficiency and durability. Hence, great efforts have been invested in this area of research. Especially in regards of organic redox-active species (RAS) a wide variety of different molecular design approaches have been examined. While many of these RAS are convincing due to their simple synthesis and cheap raw materials (cheap production) as well as high redox potentials (high cell voltage), high redox reversibility and low crossover tendency (high long-time stability), or high solubilities (high capacity), only a few can combine all these requirements for an optimal RAS.In this work, we therefore present the functional group of ketazines (see Figure 1) as basis for organic RAS potentially exceeding previous organic RAS in RFB performance. With its simple two-step synthesis, easy variation of functionalization and low-cost raw material, this functional group offers not only high variability but also adaptability to specific NARFB (non- aqueous RFB) needs. This functional ketazine group is exemplary shown by the molecule AMAP here (see Figure 2).In addition, we present a simple experimental procedure that can be used to analyse crossover rates of an RFB system (i.e. RFB cell structure, electrolyte composition and separator / membrane). To this end, we have developed a crossover mass transport concept that allows qualitative and quantitative crossover investigations. Using this experimental route, it is shown how different operating parameters within a specific RFB setup (e.g. RAS concentration, RAS structure, type of separator / membrane, ...) can influence the crossover behaviour of the RAS, and thus the resulting capacity loss. In this way, the comparability of different RFB systems can be improved and the best combination of RFB cell structure, electrolyte composition and separator/membrane for most efficient long-term charge-discharge cycling can be selected. Figure 1

Regulating Steric Hindrance in Redox Coupling of Single Organic Molecule for High Performance Organic Batteries

Since the use of tricarbonyl compounds (e.g. dichloroisocyanuric acid) as electrode materials for primary lithium batteries dates back to the 1960s, organic molecules have received significant attention as a means to further advance the state-of-the-art electrode materials for rechargeable batteries due to their advantages, including abundance, high energy density, design flexibility, environmentally benign nature, mild synthesis processes, and cost competitiveness. Numerous molecular design strategies have been employed to achieve high performance in organic electrode materials for rechargeable batteries. For examples, the organic molecular structure can be optimized to provide high specific capacity by minimizing the redox-inactive parts, exploiting multiactive centers, or introducing electron activating and deactivating groups. In addition, cycle stability can be controlled by polymerization of the active-molecules and electrical conductivity can be increased by enhancing electron delocalization, inter- (p-d) and intra-molecular (p-p) conjugation in aromatic rings of the organic molecules.Herein, we provide a novel design of organic electrode for high discharge voltage with superior cycling stability in rechargeable battery by using steric effect of substituted the single molecule. 16,17-dihydroxyviolanthrone (DHV) molecule was used as a single molecule model for control group because the violanthrone compound has a planar conformation overlapping sp2 hybridized carbon and its hydroxyl groups that can be substituted with a variety of substituents. The electrochemical performance of DHV cathode and its reversible redox process in rechargeable battery system were demonstrated through experimental and theoretical identification at the first time. To further advance the battery performance of the DHV through the steric hindrance effect, we substituted main functional group (-OH) of DHV nearby p-type redox center with long-chain alkoxy group (-OC8H17 or -OC10H21) leading to ether, which are dioctiloxyviolanthrone (DOV) and didecyloxyviolanthrone (DDV), respectively.In comparison to DHV, DOV and DDV showed significant increase of redox potential of the oxidation reaction allowing battery with around 0.6 V higher operating voltage. We further substantiated the steric hindrance effect from long-chain alkoxy groups on coupling electrolyte anion (PF6 -) with charged DOV and DDV via computational simulation and theoretical studies based on density functional theory (DFT). Moreover, we showed that the bipolar nature of the violanthrones allows its application in symmetrical cells, though the cycling performance was limited by the reduction reaction stability. Additionally, we demonstrated that finding of the more suitable electrolyte could lead to greatly enhanced stability of the violanthrone electrodes allowing up to 2000 cycles without capacity reduction and reduced voltage decay. Finally, based on various analytical methods, we demonstrated that the oxidation occurs through withdrawing of the delocalized electrons from the large conjugated structure of the violanthrones, and that the main the p-type redox site could be determined to be the moiety of (-(ROC)C-C-C-C(COR)-). Thus, this molecular design approach allows development of organic cathode with a high redox potential, comparable to the conventional cathode materials, and potentially may lead to future all-organic symmetric batteries.

Utilizing the Effect of Chalcogen Atoms in Carbazole Based SAM for Achieving High Efficiency in Inverted Perovskite Solar CELLS

In the realm of inverted perovskite solar cells (PSCs), self-assembled monolayers (SAMs) have emerged as a prominent choice for the hole-selective layer (HSL). Apart from their role in tailoring electrical characteristics, the molecular engineering of SAMs offers a pathway to mitigate buried defects in perovskite materials. Here, we proposed a targeted strategy for passivating buried defects through the chalcogen effect, achieved by introducing the sulfur heteroatom. The sulfur atoms within in (4-(3,6-bis(methylthio)-9H-carbazol-9-yl)butyl)phosphonic acid (MeS-CzC4PA) possess the ability to form coordination bonds with Pb2+ ions, effectively mitigating defects at the buried interface. As a result, the PSCs based on MeS-CzC4PA show a PCE of 24.2%, primarily attributed to a significant increase in the fill factor (FF). Insights gained from this molecular design approach will propel the development of advanced functional SAM HSLs, thereby augmenting the efficiency of PSCs.

Correlation between Membrane Permeability and the Intracellular Degradation Activity of Proteolysis-Targeting Chimeras.

Proteolysis-targeting chimeras (PROTACs) have attracted attention as an innovative drug modality that induces the selective degradation of target proteins. This technology shows higher activity than conventional inhibitors and holds great potential in the field of drug discovery. Optimization of the linker is essential for PROTACs to achieve sufficient activity, particularly with regard to cell membrane permeability. However, the correlation between membrane permeability and the activity of PROTACs has not been fully explored. To address this, we established a new molecular design approach to remove the linker and optimize PROTAC structure. These PROTAC compound groups were used to analyze the correlation between membrane permeability and activity using LC-tandem mass spectrometry (LC-MS/MS). Results revealed that the degradation activity of PROTACs fluctuates with increasing membrane permeability and changes in response to linker optimization, while sufficient proteolytic activity can be retained. These findings demonstrate the importance of considering the balance between membrane permeability and activity in PROTAC design and provide a new strategy for developing more effective PROTACs.

Impact of molecular structure on the biological removal efficiency of fluoroquinolone antibiotics: An in-silico approach

Fluoroquinolone antibiotics (FQs), one of the most widely used antibacterials, have been recognized as emerging contaminants with adverse human health concerns. To overcome the adverse effects, a theoretical molecular design and screening approach was developed in this study to improve the removal efficiency of FQs by Chlorella in artificial or natural wetland systems. Among the 189 designed norfloxacin (NOR) derivatives, NOR-140 was screened with significantly improved biosorption, bioaccumulation, and biodegradation removal and functional effects, and reduced human health and ecological risks. The removal mechanism NOR-140 was also analyzed using adsorption kinetics, molecular docking, molecular dynamics simulations and machine learning models. Protein and polysaccharide structures play a major role in the adsorption process, polarizability and molecular volume of NOR-140 affect the bioaccumulation ability, and hydrogen bonding was found as the key force promoting the degradation ability of NOR-140. Modifying specific sites (5, 8, and 13) with functional groups containing highly electronegative atoms (O, F) significantly enhances the biodegradability of FQs alternatives by Chlorella. This study provided theoretical support for designing environmentally friendly FQs alternatives with improved degradation ability and advanced the understanding of how the FQs' molecular structures affect its removal by Chlorella.

Synergistic π-Extension and Peripheral-Locking of B/N-Based Multi-Resonance Framework Enables High-Performance Pure-Green Organic Light-Emitting Diodes.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters offer natural advantages for creating power-efficient, wide-color-gamut OLEDs. However, current green MR-TADF emitters face challenges in simultaneously achieving high color purity and efficient reverse inter-system crossing (RISC), leading to suboptimal device performance. In this study, we propose a synergistic molecular design approach that combines π-extension and peripheral locking to address these challenges. This approach allows for the construction of quadruple borylated MR-TADF emitters that not only deliver precisely tuned pure-green emission with a narrow full width at half maximum (FWHM) of 15 nm, but also exhibit close-to-unity quantum yield, rapid RISC, and optimal horizontal dipole orientation. The resulting sensitizer-free OLED approaches the BT.2020 standard with CIE coordinates of (0.18, 0.74) and demonstrates impressive external quantum efficiency (EQE) of 36.6 % at maximum and 31.8 % at 1000 cd m-2. Additionally, the device shows good operational stability, with a lifetime (LT80) of 485 hours at an initial luminance of 1000 cd m-2. This study hence offers a promising molecular design strategy that effectively enhances the comprehensive OLED performance.

Synergistic π‐Extension and Peripheral‐Locking of B/N‐Based Multi‐Resonance Framework Enables High‐Performance Pure‐Green Organic Light‐Emitting Diodes

Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters offer natural advantages for creating power‐efficient, wide‐color‐gamut OLEDs. However, current green MR‐TADF emitters face challenges in simultaneously achieving high color purity and efficient reverse inter‐system crossing (RISC), leading to suboptimal device performance. In this study, we propose a synergistic molecular design approach that combines π‐extension and peripheral locking to address these challenges. This approach allows for the construction of quadruple borylated MR‐TADF emitters that not only deliver precisely tuned pure‐green emission with a narrow full width at half maximum (FWHM) of 15 nm, but also exhibit close‐to‐unity quantum yield, rapid RISC, and optimal horizontal dipole orientation. The resulting sensitizer‐free OLED approaches the BT.2020 standard with CIE coordinates of (0.18, 0.74) and demonstrates impressive external quantum efficiency (EQE) of 36.6% at maximum and 31.8% at 1000 cd m‐2. Additionally, the device shows good operational stability, with a lifetime (LT80) of 485 hours at an initial luminance of 1000 cd m‐2. This study hence offers a promising molecular design strategy that effectively enhances the comprehensive OLED performance.

Biomass and Transparent Supramolecular Elastomers for Green Electronics Enabled by the Controlled Growth and Self-Assembly of Dynamic Polymer Networks.

Determining the optimal method for preparing supramolecular materials remains a profound challenge. This process requires a combination of renewable raw materials to create supramolecular materials with multiple functions and properties, including simple fabrication, sustainability, a dynamic nature, good toughness, and transparency. In this work, a strategy is presented for toughening supramolecular networks based on solid-phase chain extension. This toughening strategy is simple and environmentally friendly. In addition, a series of biobased elastomers are designed and prepared with adjustable performance characteristics. This strategy can significantly improve the transparency, tensile strength, and toughness of the synthesized elastomer. The synthesized biobased elastomers have great ductility, repairability, and recyclability, and they show good adhesion and dielectric properties. A biobased ionic skin is assembled from these biobased elastomers. Assembled ionic skin can sensitively detect external stimuli (such as stretching, bending, compression, or temperature changes) and monitor human movement. The conductive and dielectric layers of the biobased ionic skin are both obtained from renewable raw materials. This research provides novel molecular design approaches and material selection methods for promoting the development of green electronic devices and biobased elastomers.

Molecular Design and Synthetic Approaches for the Realization of Multichannel Radiative Decay Pathways in Gold(III) Complexes and Their Applications in Organic Light-Emitting Devices.

A unique class of tridentate diaryltriazine ligand-containing gold(III) complexes with thermally activated delayed fluorescence (TADF) and/or thermally stimulated delayed phosphorescence (TSDP) properties has been designed and synthesized. With a simple structural modification on the coordination of carbazole moiety in the monodentate ligand, a large spectral shift of ∼160 nm (ca. 4900 cm-1) spanning from sky blue to red emissions has been demonstrated in solid-state thin films. Three-state or four-state models have been employed in fitting the emission lifetimes of the gold(III) complexes at various temperatures. The findings clearly indicate the presence of three emitting states, S1, T1, and T1', suggesting the coexistence of TADF, phosphorescence, and TSDP. Notably, a minor structural change in the donor moiety between phenylcarbazolyl and diphenylaminoaryl has been demonstrated to turn on/off the TSDP, resulting in TADF-TSDP-phosphorescence or TADF-phosphorescence emitters. The TADF and/or TSDP properties have also been supported by temperature-dependent ultrafast transient absorption studies, with the direct observation of reverse intersystem crossing (RISC) and reverse internal conversion (RIC) and the determination of the activation parameters and excited state dynamics. Solution-processed and vacuum-deposited organic light-emitting devices (OLEDs) have been prepared, in which sky blue emitting devices based on 5 exhibit an operational lifetime LT70 ∼ 5 times longer than the previously reported sky blue emitting analogue that shows only TSDP property. These results have provided valuable insights into the manipulation of the excited states via rational molecular design toward the realization of gold(III)-based TSDP and/or TADF materials with multiple radiative decay pathways that show enhanced radiative decay rate constants (kr) for practical OLED applications.

Molecular Design of Active Layer for High-Performance Stretchable Organic Solar Cells.

Stretchable organic solar cells (SOSCs) have advanced rapidly in the last few years as power sources required to realize portable and wearable electronics become available. Through rational material and device engineering, SOSCs are now able to retain their photovoltaic performance even when subjected to repeated mechanical deformations. However, reconciling a high efficiency and an excellent stretchability is still a huge challenge, and the development of SOSCs has lagged far behind that of flexible OSCs. In this perspective article, recent strategies for imparting mechanical robustness to SOSCs while maintaining high power conversion efficiency are reviewed, with emphasis on the molecular design of active layers. Initially, an overview of molecular design approaches and recent research advances is provided in improving the stretchability of active layers, including donors, acceptors, and single-component materials. Subsequently, another common strategy for regulating photovoltaic and mechanical properties of SOSCs, namely multi-component system, is summarized and analyzed. Lastly, considering that SOSCs research is in its infancy, the current challenges and future directions are pointed out.

Theoretical investigation of benzodithiophene-based donor molecules in organic solar cells: from structural optimization to performance metrics.

Achieving high power conversion efficiency (PCE) remains a significant challenge in the advancement of organic solar cells (OSCs). In the field of organic photovoltaics (OPVs), considerable progress has been made in optimizing molecular structures to improve the PCE. However, innovative material design strategies specifically aimed at enhancing PCE are still needed. Here, we have designed BDTS-2DPP-based molecules and propose a molecular design approach to develop donor materials that can significantly improve the PCE of OSCs. Density functional theory (DFT) and time-dependent DFT (TD-DFT) methods have been adopted in both gas and solvent phases. Our newly designed molecule M1 shows the highest absorption value (λ max = 846 nm), highest electron reorganization energy (λ e = 0.18 eV), and the lowest energy gap (E g = 1.81 eV) among all the designed molecules. M1 molecule also exhibits the highest dipole moment in both gas (10.62 D) and solvent phase (13.62 D), and their ground and excited state dipole moment difference is also higher (μ e - μ g = 2.99 D), which enhances its separation to make it a suitable candidate for charge transfer between HOMO-LUMO (97%). Newly designed molecule M3 is observed to have the highest voltage when the current is zero (V oc = 1.15 V) highest PCE value (21.90%) and highest fill factor (FF) value (89.42%). The lowest excitation binding energy is estimated by newly designed molecule M2 (E b = 0.30 eV), which indicates a higher rate of dissociation during the excitation as observed in transition density matrix (TDM) plots. Utilizing electron density difference maps, the newly designed molecules in dichloromethane solvent exhibited consistent intramolecular charge transfer (ICT). The designed molecules were evaluated against reference molecule R to determine if they exhibit superior optoelectronic capabilities. It is found that all designed molecules (M1-M5) exhibit reduced band gaps, are red-shifted in wavelength in comparison to a reference molecule R, and have remarkable charge motilities in terms of reorganisation energies.

Design of Linear-Polymer-Coated Graphene Nanosheets with π-Conjugated Structure and Multi-Active-Center for Long-Lifespan and High-Rate Li-Storage Performance.

Organic material holds immense potential for Li-ion batteries (LIBs) due to their eco-friendly nature, high structural designability, abundant sources, and high theoretical capacity. However, the limited redox-active sites, low electronic conductivity, sluggish ionic diffusion, and high solubility hinder their practical application. Here, we reported the use of a linear polymer called poly(naphthalenetetracarboxylic dianhydride-pyrene-4,5,9,10-tetraone)-coated graphene nanosheets (NPT/rGO) as a cathode material for LIBs. The NPT polymer has a rotation angle of approximately 63° between each plane, which helps in exposing the active sites and preventing structural pulverization during cycling. The highly conjugated skeleton of the polymer, along with graphene, forms a synergistic effect through a π-π interaction. This combination enhances the conductivity and restricts solubility. Additionally, the linear structure of NPT and the two-dimensional rGO substrates work together to enhance charge transfer and ion diffusion rates, resulting in faster reaction kinetics. Consequently, NPT/rGO exhibits excellent electrochemical performance in terms of high capacity, superior cyclic stability, and good rate capability for LIBs. Moreover, through the combination of experimental investigations and theoretical simulations, a multiple electron reaction mechanism, an efficient Li-ion storage behavior, and a reversible dynamic evolution have been revealed. This study introduces a rational molecular design approach to enhance the electrochemical performance of polyimide derivatives, thereby contributing to the advancement of cutting-edge organic electrode materials for LIBs.

Non-Fullerene Organic Electron Transport Materials toward Stable and Efficient Inverted Perovskite Photovoltaics.

Inverted perovskite solar cells (PSCs) attract continuing interest due to their low processing temperature, suppressed hysteresis, and compatibility with tandem cells. Considerable progress has been made with reported power conversion efficiency (PCE) surpassing 26%. Electron transport Materials (ETMs) play a critical role in achieving high-performance PSCs because they not only govern electron extraction and transport from the perovskite layer to the cathode, but also protect the perovskite from contact with ambient environment. On the other hand, the non-radiative recombination losses at the perovskite/ETM interface also limits the future development of PSCs. Compared with fullerene derivatives, non-fullerene n-type organic semiconductors feature advantages like molecular structure diversity, adjustable energy level, and easy modification. Herein, the non-fullerene ETM is systematically summarized based on the molecular functionalization strategy. Various types of molecular design approaches for producing non-fullerene ETM are presented, and the insight on relationship of chemical structure and device performance is discussed. Meantime, the future trend of non-fullerene ETM is analyzed. It is hoped that this review provides insightful perspective for the innovation of new non-fullerene ETMs toward more efficient and stable PSCs.

Unveiling the potential of TPA-based molecules to tune the optoelectronic properties and enhance the efficiency of dye-sensitized solar cells.

The world's energy and environmental requirements are changing due to rapid population growth and industrial growth, and solar cells can be used to meet these demands. Dye-sensitized solar cells (DSSCs) are solar cells in which energy conversion occurs via a process similar to photosynthesis in plants. DSSC development is still in its infancy. DSSCs can operate under cloudy conditions and indirect sunlight and have attracted considerable attention due to their low cost and high efficiency. We designed two metal-free TPA-based dyes (Dye2 and Dye3) based on the reference dye Mg207 (Dye1) by increasing the donor strength of the molecule, as such dyes have shown enhanced efficiency in DSSCs. Moreover, the triphenylamine (TPA) moiety has been demonstrated to be a good donor that prevents charge recombination. Intramolecular charge transfer (ICT) from the donor to acceptor moiety was found in the sensitizers, and electrons were promoted to the conduction band (CB) of the TiO2 semiconductor. The negative binding energy of the dye@TiO2 clusters indicated that dye adsorption on the semiconductor surface was stable. The double donor increased the electron injection and electronic coupling constants in Dye2 and Dye3, indicating that these newly designed dyes have superior charge injection capacity. Accordingly, the efficiencies of DSSCs with Dye2 and Dye3 were 9.77% and 9.62%, respectively, and substitution with the TPA unit at the -R1 and -R2 positions in Dye1 resulted in better power conversion compared to the parent compound (9.09%). Increased donor strength improved photovoltaic performance by increasing current density and light-harvesting efficiency. This is a good molecular design approach for preparing targeted donor- -acceptor (D- -A) organic dyes with high DSSC efficiency. To predict the charge transport and optoelectronic characteristics of the TPA dyes, quantum chemical calculations were carried out using Gaussian16. The ground-state (S0) optimized geometries of the sensitizers were computed by utilizing DFT at the B3LYP/6-31G** level. The absorption spectra ( max) were computed by employing TD-DFT with various functionals (B3LYP, PBE1PBE, CAM-B3LYP, and BHandHLYP) in the gas and solvent (DCM) phases. Among the studied functionals, BHandHLYP was found to be best at successfully reproducing the experimental data. Thus, the absorption spectra of the newly designed dyes and dye@TiO2 were calculated at the BHandHLYP/6-31G** level. The dye@TiO2 cluster optimizations were carried out at the B3LYP/6-31G**(LANL2DZ) level.

An activatable azophenyl fluorescent probe for hypoxic fluorescence imaging in living cells.

Cellular hypoxia is a common pathological process in various diseases. Detecting cellular hypoxia is of great scientific significance for early diagnosis of tumors. The hypoxia fluorescence probe analysis method can efficiently and conveniently evaluate the hypoxia status in tumor cells. These probes are covalently linked by hypoxic recognition groups and organic fluorescent molecules. Currently, the fluorescent molecules used in these probes often exhibit the aggregation-caused quenching effect, which is not conducive to fluorescence imaging in water. Herein, an activatable hypoxia fluorescence probe was constructed by covalently linking aggregation-induced emission luminogens to the hypoxic recognition group azobenzene. It does not emit fluorescence in solution and in solid state under light excitation due to the presence of photosensitive azo bonds. It can be cleaved by intracellular azoreductase into fluorescent amino derivatives with aggregation-induced emission characteristic. As the concentration of oxygen in cells decreases, its fluorescence intensity increases, making it suitable for fluorescence imaging to detect hypoxic environment in live cancer cells. This work broadens the molecular design approach for activatable hypoxia fluorescent probes.

Charge separation control in organic photosensitizers for photocatalytic water splitting without sacrificial electron donors

Photocatalytic hydrogen evolution reaction (photoHER) is one of the most promising approaches towards production of “green” hydrogen. Currently, the state-of-the-art photoHER systems require the use of sacrificial electron donors (SED), because of inefficient charge separation in photosensitizers and thermodynamically challenging water oxidation by the same catalyst. Here, we present a molecular design approach for all-organic photosensitizers with effective intramolecular charge separation, microsecond lifetime of excited states, controllable direction of electron transfer, and ability to oxidize water for recovery of the photocatalytic system to its initial state. Such photosensitizers comprise weakly conjugated strong electron donor and acceptor what enables charge transfer during the light absorption. The excitation energy is stored in long-living triplet states, whose lifetime can be monitored by the thermally activated delayed fluorescence. Additionally, application of heavy-atom effect helps not only to increase the population of triplet state but also to increase its stability and lifetime. When such photosensitizers are attached to the platinized TiO2, efficient photoHER catalysts are obtained which produce H2 under irradiation with sunlight. In the presence of SED, the highest turnover number after 24 h (TON24h) of such systems exceed 3500, whilst in pure water without any SED, TON24h reaches 2000. Our best system performs photocatalytic SED-free water-splitting for 48 h keeping 100 % of its activity and constant turnover frequency of 26 h−1. The described here investigations reveal that water splitting can be performed by a simple three component system “photosensitizer|TiO2|Pt” under specific control of 1) the charge separation and its direction, 2) intersystem crossing rate and triplet state lifetime, and 3) favorable water oxidation thermodynamics within a photosensitizer together with 4) appropriate alignment of energy levels to the catalyst.

Brightness Strategies toward NIR-II Emissive Conjugated Materials: Molecular Design, Application, and Future Prospects.

Recent advances have been made in second near-infrared (NIR-II) fluorescence bioimaging and many related applications because of its advantages of deep penetration, high resolution, minimal invasiveness, and good dynamic visualization. To achieve high-performance NIR-II fluorescence bioimaging, various materials and probes with bright NIR-II emission have been extensively explored in the past few years. Among these NIR-II emissive materials, conjugated polymers and conjugated small molecules have attracted wide interest due to their native biosafety and tunable optical performance. This review summarizes the brightness strategies available for NIR-II emissive conjugated materials and highlights the recent developments in NIR-II fluorescence bioimaging. A concise, detailed overview of the molecular design and regulatory approaches is provided in terms of their high brightness, long wavelengths, and superior imaging performance. Then, various typical cases in which bright conjugated materials are used as NIR-II probes are introduced by providing step-by-step examples. Finally, the current problems and challenges associated with accessing NIR-II emissive conjugated materials for bright NIR-II fluorescence bioimaging are briefly discussed, and the significance and future prospects of these materials are proposed to offer helpful guidance for the development of NIR-II emissive materials.

Enhancing the Luminescence Efficiency of Blue Phosphorescent Organic Light‐Emitting Diodes: Constructing Platinum(II) Complexes with a Functionalized Tetradentate Ligand

AbstractEfficient, electrochemically stable blue phosphors are essential for advancing the organic light‐emitting diode (OLED) industry. Specifically, the characteristics of these phosphors must be further refined to realize commercially viable OLED devices with high stability, efficiency, and color purity. To that end, a new simple molecular design approach is devised in this study for synthesizing tetradentate‐ligand‐based Pt(II) complexes exhibiting intense blue emission. Essentially, novel Pt(II) complexes Pt3 and Pt4 are prepared by introducing the tert‐butyl and cyano groups to the ligand of previously reported highly stable, efficient Pt(II) complexes for preventing molecular aggregation and regulating the frontier levels, respectively, and then fully characterized. Both complexes display a blue emission band in solution and solid states with remarkably low full‐width‐at‐half‐maximum values. Additionally, multilayer phosphorescent OLEDs are fabricated using Pt3 or Pt4 as emitters and SiCzCz/SiTrzCz2 as a mixed‐host system. The devices demonstrate outstanding performance parameters, such as higher efficiencies than those of the devices containing the previously reported Pt(II) complexes and good color purity (CIEy ≈ 0.18). These findings suggest that the molecular design approach employed in this study for creating tetradentate‐ligand‐based Pt(II) blue phosphors is effective and can potentially expedite the commercialization of blue phosphorescent emitters in the OLED industry.

Synergistic Inter‐ and Intramolecular Aggregation of Dimeric Cyanine Dyes Affords Highly Efficient In Vivo Self‐Delivery and Photothermal Therapy

AbstractAdvancing photothermal therapy hinges on developing PTAs with robust in vivo delivery and therapeutic efficacy. However, effective molecular design approaches for high‐performance PTAs remain lacking. Herein a strategic design of dimeric heptamethine cyanine (Cy7) molecules is presented, covalently linked via ortho/meta/para‐phenyldithiol. These designs facilitate spontaneous nanoparticle assembly in water, attributed to efficient intermolecular aggregation, enhancing in vivo delivery. Additionally, aggregation between intramolecular Cy7 units promotes superior photothermal conversion efficiency (PCE) up to 74.1% for meta‐dimer. Remarkably, the para‐dimer variant not only achieves a high PCE of 61.1% but also exhibits the most effective pharmacokinetic profile, leading to unparalleled anticancer efficacy in vivo. This dual aggregation strategy, leveraging both inter‐ and intramolecular dynamics, equips dimeric Cy7 with superior self‐delivery and photothermal efficacy, offering a promising approach for the next generation of photothermal therapeutics.

Molecular Design of Sexiphenyl-Based Liquid Crystals: Towards Temperature-Stable, Nematic Phases with Enhanced Optical Properties.

This research introduces a novel liquid crystal molecular design approach based on the para-sexiphenyl (6P) structure. Six new liquid crystalline materials were synthesized, incorporating an alkyl terminal and lateral substitutions of the sexiphenyl core to achieve temperature-stable and broad nematic phases. The synthetic pathway involved cross-coupling, resulting in derivatives with strong nematogenic characteristics. Optical investigations demonstrated that the tested material had high birefringence values, making it promising for optical and electronic applications. These results open up new avenues of research and offer potential practical applications in electronics, photonics, optoelectronics and beyond.