Highly brightness fluorophore in the second near-infrared (NIR-II) window is promising for noninvasive and rapid-response clinical surgical phototheranostics. However, it is an appealing yet significantly challenging work to develop such fluorophores with advancements of ACQ/AIE dual properties and brightness emission to overcome the influence of in vivo internal microenvironment. Herein, we first propose two superior brightness NIR-II luminogens (named as CTU4 and CTU5) with such properties to bridge the gap between surgical requirements and molecular development. The luminogens were constructed via the introduction of two cage moieties to locking their intramolecular motion, endowing the fluorophores with brightness NIR-II emission in the molecular and aggregate states. The CTU5 was demonstrated that reveals this characteristic with quantum yield of 1.7% in molecular state and 7.1% in aggregate state. Moreover, the water-dispersible CTU5 nanoparticles process a tumorto-background ratio of 12.4 for tumor removal, photothermal conversion efficiency of 59.2%, and efficient type-I reactive oxygen species generation ability, contributing to its photoluminescent/photothermal dual images-guided surgical anti-tumor phototheranostics. This work highlights the intramolecular locking strategy to achieve NIR-II diagnostic agent with ACQ/AIE dual properties and their potential surgical antitumor phototherapy.

ABSTRACT Recently, growing single crystals of covalent organic polymers (COPs) through dative B←N bonds has been proven to be a promising strategy. Despite these developments, constructing diverse COP structures using identical structural motifs to investigate the variations in their performance remains a significant but challenging task. In this paper, we introduce a strategy aimed at reducing the symmetry of structural units to achieve this target. By employing the 3‐pyridyl‐based tetrathiafulvalene motif (labeled as TTF‐(3‐py) 4 ), a series of single‐crystal COP structures sharing the same motifs, including one‐dimensional (1D) zigzag chains ( CityU‐61 ), 1D nanobelt ( CityU‐62 ), and 2D layer ( CityU‐63 ) structures, are constructed under different solvent conditions. The rotatability of the carbon‐carbon single bond, coupled with the deviation of nitrogen in pyridine from the symmetry axis, endows TTF‐(3‐py) 4 with a diverse range of configurations. These COP compounds exhibit excellent light absorption properties and redox activities, facilitating efficient photocatalytic synthesis of hydrogen peroxide (H 2 O 2 ) from water and air. Notably, CityU‐63 exhibits the highest catalytic activity, with an H 2 O 2 production rate of 10 488.9 µmol g −1 h −1 , positioning it among the most effective photocatalysts currently employed for H 2 O 2 photosynthesis.

Nanomedicine has revolutionized the landscape of cancer theranostics. However, developing nanodrugs with effective penetration and prolonged retention remains challenging. Here, we report a stimuli-independent transformable nanophotosensitizer (SITNPS), which can transform from thermodynamically metastable nanospheres to stable nanorods, improving tumor penetration and retention. The unique sterically undemanding donor-π-acceptor molecule displays enhanced non-covalent coupling, facilitating SITNPS formation. With robust two-photon-excited characteristics and excellent singlet oxygen generation, SITNPS induces redox homeostasis imbalance, mitochondrial dysfunction, and DNA damage. SITNPS effectively inhibits tumor growth by triggering two-photon or smartphone-torch-activated photodynamic therapy (PDT), overcoming limitations of inadequate light penetration and dependence on specialized equipment. Due to prolonged retention, portable light could be given three times with a single administration, enhancing tumor inhibition compared to clinical photosensitizers. This work presents a promising paradigm of stimuli-independent self-transforming nanophotosensitizers to facilitate practical translation of long-term tumor-retaining nanomedicines and broadens PDT applications in deep-seated tumors with penetrable and portable light sources.

The performance and operational stability of inverted organic solar cells (OSCs) are often limited by charge recombination and interfacial instability at the electron transport layer (ETL). To address this, we designed two fullerene-based self-assembled monolayers (SAMs)-C2-PA and 4EG-PA-as interfacial modifiers for zinc oxide (ZnO). Systematic comparisons reveal that the tetra(ethylene glycol) linker in 4EG-PA induces a denser and more uniform SAM morphology than the alkyl chain in C2-PA, which more effectively passivates the polar ZnO surface. This superior molecular packing translates into a champion power conversion efficiency of 19.46%. More critically, transient absorption spectroscopy (TAS) provides direct evidence that the 4EG-PA-modified interface facilitates the formation of a favorable charge-transfer state, which not only promotes electron extraction but also enhances hole transfer efficiency from the acceptor to the donor, thereby suppressing non-geminate recombination. Concurrently, the dense SAM acts as a robust buffer, improving the thermodynamic compatibility with the active layer and inhibiting its deleterious reaggregation. This dual mechanism-enhanced charge extraction and optimized interfacial morphology-underpins the exceptional operational stability, with devices retaining 84% of their initial performance after 2000 h. Our work elucidates the critical link between SAM molecular structure, interfacial properties, and device longevity, providing a strategic blueprint for future interfacial material design.

To address the issues of uncontrollable lithium dendrite growth and an unstable solid electrolyte interphase (SEI) in lithium anodes, we designed an asymmetric and multifunctional COF material (CityU-55) composed of strongly solvating polyether and highly electronegative fluoroalkyl side groups. This material was employed as an artificial interphase layer to create a fast lithium-ion-conducting and fluorine-rich interphase on the anode, thereby mitigating interfacial problems. Notably, the introduction of side chains enhanced the solubility of the COF material, significantly improving its processability. This asymmetric COF enables distinct interfacial regulation. The CityU-55@Li anode exhibited improved reversibility of lithium deposition and substantially reduced the number of interfacial side reactions. Leveraging these synergistic properties, the lithium anode with this multifunctional artificial interphase layer showed a low nucleation barrier of 28 mV and excellent cycling stability of 4500 h at 1 mA cm-2 and 1 mAh cm-2. Additionally, compared with bare lithium anodes, full cells paired with LiFePO4 and LiNi0.8Co0.1Mn0.1O2 cathodes demonstrated remarkably better cycling stability, capacity retention, and capacity utilization at high rates. Our research indicates that asymmetric multifunctional side-chain engineering in COFs significantly expands structural diversity and provides a promising strategy for the development of high-performance lithium metal batteries.

The development of solid-state electrolytes is restricted by sluggish ion transport and unstable electrode-electrolyte interfaces. To address this issue, we introduce a paradigm-shifting approach that actively converts cycling-induced mechanical stress into an electrochemical driving force for ion migration. Through strategically structural engineering of a covalent organic framework (COF), we create a piezoelectric COF (CityU-57) with a broken structural symmetry, enabling a built-in electric field under mechanical stress (piezoelectric field). This structural modification not only decreases the HOMO energy level to improve oxidative stability but also enhances Li+ affinity and reduces migration barriers, especially under a piezoelectric field. When implemented as a solid electrolyte, CityU-57 achieves exceptional performance, including a high Li+ transference number (0.539), low interfacial resistance, and unprecedented cycling stability exceeding 5000 h in symmetric cells. Comprehensive characterization through piezo-response force microscopy, electrochemical analysis, and theoretical calculations, we verify a "mechano-electric coupling" mechanism where mechanically induced piezoelectric fields function as a dynamic "ion pump" to facilitate Li+ transport and homogenize the deposition.

Correction for 'Planar rotor-enabled quenching-resistant NIR-II fluorophores for high-contrast bioimaging and efficient cancer phototheranostics' by Weilong Chen et al., Mater. Horiz., 2026, 13, 6665-6678, https://doi.org/10.1039/d6mh00067c.

Accurate assessment of inflammatory bowel disease (IBD) severity is crucial for optimizing treatment decisions and improving prognosis. However, conventional assessment methods are time-consuming and primarily detect anatomical changes at moderate or late stages, limiting timely intervention. Here, we report an HClO‑responsive NIR‑IIb ratiometric nanosensor (CSSS@PMH‑mPEG2000) that combines down‑conversion core-shell nanoparticles with strong NIR‑IIb emission under 808/980 nm excitation and an HClO‑responsive IR780MA dye. By means of dye sensitizing mechanism, the sensor enables dynamic ratiometric quantification of HClO and supports real-time assessment of IBD progression and severity. Comprehensive in vitro and in vivo studies validate CSSS@PMH‑mPEG2000 as a highly sensitive and reliable platform for real-time, quantitative HClO monitoring of IBD in a mouse model. Moreover, ratiometric NIR‑IIb fluorescence imaging effectively captures changes in disease severity, highlighting its potential for assessing treatment efficacy. Together, these findings underscore the translational value of CSSS@PMH‑mPEG2000 for advancing IBD diagnosis and management, while also demonstrating its broader applicability to in situ HClO detection across a range of inflammatory diseases. STATEMENT OF SIGNIFICANCE: Accurate IBD severity assessment is vital for optimizing treatment and prognosis, but conventional methods are time‑consuming and detect mainly mid‑to‑late anatomical changes, delaying intervention. We present an HClO‑responsive NIR‑IIb ratiometric nanosensor (CSSS@PMH‑mPEG2000) combining down‑conversion core-shell nanoparticles with an HClO‑responsive IR780MA dye. Using dye sensitizing mechanism, it enables dynamic ratiometric HClO quantification and real‑time evaluation of IBD progression and severity. In vitro and in vivo studies in a mouse IBD model demonstrate high sensitivity and reliability for real‑time, quantitative HClO monitoring. Ratiometric NIR‑IIb imaging captures disease‑severity changes and supports treatment‑efficacy assessment, underscoring the platform's translational value for IBD management and broader in situ HClO detection in inflammatory diseases.

Quenching-resistant near-infrared-II (NIR-II) fluorophores with strong light harvesting capabilities and excellent photophysical properties remain a critical challenge in cancer phototheranostics. Herein, we report a novel acceptor-donor-acceptor (A-D-A) fluorophore, BTP-2TCF, constructed by introducing planar, rotatable tricyanofuran (TCF) acceptors into the core of the high-performance dye Y6. This molecular design imparts obvious anti-quenching behavior to BTP-2TCF nanoparticles (NPs), achieving an improved photoluminescence quantum yield of 1.9% and over a ten-fold enhancement in reactive oxygen species generation compared to Y6 NPs. These improvements are likely attributed to the restricted intramolecular motion of the TCF rotor, which suppresses non-radiative energy dissipation. BTP-2TCF NPs also exhibit a high molar absorption coefficient (>82 000 M-1 cm-1) and brightness (635 M-1 cm-1), outperforming conventional anti-quenching dyes. Their bright NIR-II fluorescence enables high-contrast visualization of mouse vasculature. Guided by NIR-II fluorescence imaging, BTP-2TCF NPs demonstrate superior photodynamic and photothermal anticancer efficacy in vivo. This study highlights the TCF planar rotor as a powerful strategy for developing next-generation quenching-resistant fluorophores for biomedical applications.

ABSTRACT Organic charge transfer complexes (CTCs), formed by donor–acceptor (D–A) coassembly, have emerged as a supramolecular platform for programmable near‐infrared (NIR) optics. In their D–A assemblies, packing‐dependent electronic coupling and delocalization generate tunable charge transfer (CT) states and typically yield redshifted absorption and emission relative to the constituent molecules. This review establishes a structure‐function framework that links D–A energetics, noncovalent interactions, and packing geometry to emergent NIR optical states. Recent progress is summarized across practical material forms, including cocrystals, nanoparticles, confined assemblies, thin films, and soft matrices. We outline design principles that relate molecular selection and supramolecular organization to (i) broadband and NIR absorption, (ii) NIR emission, and (iii) polarization activity and reconfigurable optics across different material forms. In this context, low‐energy CT states formed upon photoexcitation often favor nonradiative relaxation and photothermal conversion. Efficient NIR emission, by contrast, requires preserving radiative CT pathways while suppressing nonradiative loss in low‐energy assembled states. Polarization‐active and reconfigurable responses further arise from chiral or oriented D–A organization and stimulus‐responsive CT structural changes. Overall, this review provides structure‐function guidelines for the rational engineering of organic CTCs toward programmable NIR functional optics and adaptive infrared photonic systems.

ABSTRACT Achieving atomically precise control over paramagnetic coordination environments is challenging because relaxivity's sixth power dependence on metal water distance demands sub‐angstrom precision while also requiring rapid water exchange, two inherently competing requirements in conventional systems. Here, leveraging dual‐atom coordination engineering as a rational material design strategy, we successfully synthesized a novel dual‐atom manganese‐based platform featuring a well‐defined asymmetric Mn 2 ‐N 3 O 3 geometry anchored on hierarchical boron nitride (Mn‐BN). Notably, this atomic‐level engineering achieves T1 relaxivity of 36.27 mM −1 s −1 at 3.0 T and 15.86 mM −1 s −1 at 7.0 T, approximately 10‐fold higher than those of clinical agents. Combining advanced characterizations with theoretical calculations reveals that adjacent asymmetrically coordinated Mn centers generate cooperative electronic effects that lower water adsorption energy and shorten the Mn–H distance, thereby enhancing water exchange and optimizing dipole–dipole interactions. The Mn‐BN exhibits specific magnetic resonance imaging (MRI) T1 signals for accurate tumor boundary visualization, meanwhile preferential hepatocyte uptake through specific transporters creates differential enhancement for sensitive liver metastases detection. This work positions dual‐atom coordination engineering as an effective materials design strategy for precise enhancement of MRI properties, providing new opportunities for developing advanced contrast agents with tailored biological interactions and extended imaging windows.

The electrocatalytic synthesis of urea offers a sustainable alternative to the energy-intensive industrial processes, yet it is challenged by the inefficient C-N coupling step. Herein, we employ symmetry breaking engineering to construct Mn dual-atom sites with an asymmetric electronic structure on oxygen-doped boron nitride (Mn2N3O3/BN) for efficient urea electrosynthesis from CO2 and nitrate (NO3- ). Compared to its symmetric single-atom counterpart (Mn-N4/BN), the Mn2-N3O3/BN catalyst exhibits significantly enhanced performance, achieving a urea yield rate of 43.78 mmol h-1 g- 1 at -0.6 V vs the reversible hydrogen electrode (RHE), and a Faradaic efficiency (FE) of 40.6% at -0.5 V vs. RHE, along with exceptional operational stability for over 120 h. Through a combination of in situ spectroscopic analysis and density functional theory (DFT) calculations, we demonstrate that the asymmetric dual-atom sites uniquely modulate the local electronic environment, which simultaneously enhances the adsorption of key C- and N-intermediates and lowers the energy barrier for the decisive C-N coupling step. This work highlights the critical role of asymmetric charge regulation in breaking the scaling relationship for multi-electron reactions and provides a rational design blueprint for advanced dual-atom catalysts in sustainable nitrogen and carbon conversion.

Developing an effective layer to isolate zinc anodes from electrolytes, stop side reactions and help uniform zinc deposition in aqueous zinc-ion batteries (AZIBs) is very important and highly desirable. However, most reported protective layers have less effective ion transport channels and poor zincophilicity, leading to short cycling lifetimes. To address this issue, we try to employ tetrathiafulvalene (TTF) derivatives as building units to construct single crystals of new polymers for such protection because these polymers can provide ordered ion-transport channels and strong interactions between sulfur and zinc species. Here, single crystals of a one-dimensional TTF-based organic polymer with square-wave-shaped chains, designated as CityU-51, have been prepared through the assembly of 4,4 ',5,5 '-tetra(isoquinolin-6-yl)-2,2 '-bi(1,3-dithiolylidene) and 1,4-bis(benzodioxaborole) benzene via the formation of B-N bonds. CityU-51 exhibits high zincophilicity as the TTF moieties interact strongly with zinc species, demonstrating exceptional performance in guiding uniform zinc deposition. Remarkably, the as-fabricated AZIBs utilizing CityU-51 as an anode protective layer exhibit an ultra-long lifespan exceeding 6300 hours at 1 mA cm-2. Moreover, the batteries can continuously work over 6000 hours even at an ultrahigh current density of 30 mA cm-2. A high capacity of 268.63 mAh g-1 of a full cell is observed, and a stable capacity retention ratio of 97% is maintained over 500 cycles. This study underscores the significance of functional B-N polymers and offers a novel coating option for dendrite-free anodes in AZIBs.

Non-geminate recombination in organic photovoltaics (OPVs) forms low-energy spin-triplet excitons (T1) that are known to result in irreversible, non-radiative relaxations1-5. Here we experimentally show in an OPV system incorporating a non-fullerene acceptor with a narrowed singlet-triplet gap that T1 excitons can be redissociated through the interfacial charge-transfer state to form free carriers. We corroborate this by identifying the increased population of free carriers following triplet sensitization of the acceptor in an OPV blend, and illustrate the way in which this mechanism alters the evolution of T1 and free carrier populations. We reveal how the distribution of orbitals in the molecule and exciton delocalization in aggregates affect the singlet-triplet energetics of the acceptor in the condensed phase, rendering the traffic between T1 and the spin-triplet charge-transfer state controllable. By introducing this acceptor as a ternary component into other host OPV systems, we manage to recover the triplet-mediated losses and improve OPV efficiencies by maximizing the number of extractable photocarriers. This study deepens our understanding of the fundamentals of OPVs, and shows how to develop future organic optoelectronics by demonstratating the recovery of low-energy T1 excitons into usable charges for electricity or light generation instead of heat.

This special issue celebrates the 25th Anniversary of the Centre of Super-Diamond and Advanced Films (COSDAF) at the City University of Hong Kong (CityUHK), coinciding with the 30th anniversary of CityUHK. It showcases the research contributions of both current staff and former members of COSDAF. Established in 1998 by Prof. Shuit-Tong Lee, COSDAF serves as a university-level research center, bringing together academic experts from various disciplines focused on semiconductor nanomaterials, nano-organic light-emitting displays, diamond technologies, and advanced nano-coatings. Since its inception, COSDAF has trained over 450 PhD students and postdoc fellows, many of them now serve as faculty members and leading researchers in various universities, research institutes, and industries worldwide. Additionally, COSDAF has cultivated strong collaboration with high-tech local industries, providing training and resources for research staff and students. This has established an important platform that bridges the gap between academia and industry.

Near-infrared (NIR) phototheranostics, combining photoacoustic imaging (PAI) and photothermal therapy (PTT), show great promise for cancer diagnosis and treatment. Organic molecules are excellent photothermal agents (PTAs) due to their strong NIR absorption and biodegradability. Typically, achieving good NIR response involves using fused-ring backbones, which require complex synthesis and yield lower production. In this work, 2F nanoparticles (NPs) are reported as an organic phototheranostic agent with high NIR responses, synthesized in just two simple steps with an 87% production yield for efficient PAI-guided PTT of cancer. Unlike traditional fused-ring structures, 2F is formed by joining donor and acceptor moieties with simple carbon-carbon bonds, simplifying synthesis and increasing yield. Although isolated 2F molecules have lower NIR absorption, forming NPs shifts the absorption peak from 708 to 808 nm, achieving NIR absorption comparable to state-of-the-art phototheranostics. This shift is due to significant charge transfer between dimers, forming a single-component charge-transfer complex with improved NIR absorption, as shown by absorption spectra and theoretical studies. Finally, 2F NPs demonstrate successful PAI-guided PTT of cancer under NIR excitation with strong anti-tumor performance. This work provides valuable insight into achieving both high synthesis yield and excellent photophysical performance in PTAs, advancing the development of PTT.

The rational design of electrode materials to modify their intrinsic electronic states effectively enhances the performance of rechargeable batteries. Herein, an umpolung strategy is implemented in preparing a polyimide-linked COF (CityU-47) through a polar inversion of the typical p-type triphenylamine (TPA) with a multi-carbonyl-contained n-type azatriangulenetrione (ATTO). This strategy can substantially decrease the energy level of the lowest unoccupied molecular orbital (LUMO), thereby increasing the potential for operation as a cathode material. Alongside increased specific capacity, an improved overall performance in sodium-ion batteries (SIBs) is achieved. Specifically, CityU-47 provides a high capacity of 286.31 mA h g-1 at a current density of 0.1 A g-1, and a cycle capacity of 210 mA h g-1 at 2 A g-1 over 1800 cycles is also achieved. This research offers fresh perspectives on enhancing battery performance, underscoring the importance of regulating electron structures at the atomic level.

Thermally activated delayed fluorescence (TADF) materials have received increasing attention from organic electronics to other related fields, such as bioapplications and photocatalysts. However, it remains a challenging task for TADF emitters to showcase the versatility concurrent with high performance in multiple applications. Herein, we first present such a proof-of-concept TADF material, namely, QCN-SAC, through strategically manipulating exciton dynamics. On the one hand, QCN-SAC displays obvious aggregate-induced deep-red/near-infrared emission with a high radiative rate beyond 107 s-1, thereby demonstrating nearly 100% exciton utilization under oxygen-free conditions. In a QCN-SAC-based nondoped organic light-emitting diode (OLED), a superb external quantum efficiency of 16.4% can be reached with a peak at 708 nm. On the other hand, QCN-SAC also exhibits a high intersystem crossing rate over 108 s-1 without leveraging the heavy-atom effect, which makes QCN-SAC-based nanoparticles perform well in boosting reactive oxygen species generation for imaging-guided photodynamic therapy (PDT). This work presents a fundamental principle for designing high-performance all-in-one TADF molecules for OLED and PDT applications. This discovery holds promise for advancing the development of versatile TADF materials with a range of uses in the near future.

Room-temperature phosphorescent (RTP) single crystals of covalent organic polymers (COPs) are rarely reported due to the huge challenge in preparing single crystals from solutions as well as the difficulty in realizing RTP in metal-free organic molecules. Compared to other main group elements, tellurium is rarely successfully introduced into functional single-crystal COPs. Herein, we prepared colorless single crystals of a COP (CityU-21) through a reaction between tellurinyldibenzene and [1,1'-biphenyl]-4,4'-diyl-bis(phosphonic acid). Single crystal X-ray diffraction (SCXRD) analysis indicates that CityU-21 is a one-dimensional organic polymer through the covalent connection (Te-O-P bonds) between Te(Ph)2 moieties and [HO3P-Ph-Ph-PO3H] units. Due to the existence of one unreacted OH group in each phosphonic acid unit, multiple hydrogen-bonding interactions can be formed between adjacent polymer chains, which stabilizes the structure and promotes CityU-21 to form a pseudo-two-dimensional framework. Benefiting from the integrated effect of aromatic P[double bond, length as m-dash]O parts, the heavy atoms (tellurium), and multiple hydrogen bonds, single crystals of CityU-21 display RTP behavior with a lifetime of 179 ms @ 540 nm and 158 ms @ 565 nm, a photoluminescence quantum yield of 84.69% and an afterglow time of 1.2 s. Moreover, CityU-21 can maintain its crystallinity and RTP character with an afterglow time of up to 0.8 s after immersion in different solvents for 60 hours, which can address the issue that most single crystals of RTP small molecules lose their crystallinity and RTP properties after solvent treatment.