Guangying Tan

Triplet energy transfer (TEnT) photocatalysis has emerged as a powerful tool for enabling mild and selective bond‐forming reactions. However, its generality remains limited by the intrinsic trade‐offs in existing photosensitizers (PSs). Noble metal (e.g., Ir, Ru) complexes offer high efficiency yet suffer from cost and sustainability concerns, while organic carbonyl sensitizers suffer from weak visible‐light absorption and short‐lived triplet states. Herein, we report heavy‐atom‐free organic PSs featuring a multi‐channel through‐space charge transfer (TSCT) architecture within a thermally activated delayed fluorescence (TADF) framework. A highly twisted donor‐acceptor topology enforces near‐complete frontier orbital separation, leading to ultralow singlet‐triplet energy gaps (Δ E _ST down to 0.013 eV) and thereby enabling efficient spin interconversion. Consequently, these PSs simultaneously achieve high intersystem crossing (ISC) quantum yields, microsecond‐scale triplet lifetimes, and high triplet energies ( E _T up to 63.7 kcal mol ⁻¹ ), rivaling those of state‐of‐the‐art noble‐metal systems. Leveraging these features, we demonstrate the first visible‐light‐driven intermolecular [2 + 2] cycloaddition of 1,3‐diphenylphosphindole 1‐oxides with alkenes and alkynes, enabling rapid access to structurally complex cyclobutane‐fused phosphindole 3‐oxides that hold potential value in drug screening but are typically difficult to obtain. Mechanistic studies support a TEnT pathway, in which minimal Δ E _ST and efficient ISC are key to achieving high TEnT reactivity.

Triplet energy transfer (TEnT) photocatalysis has emerged as a powerful tool for enabling mild and selective bond‐forming reactions. However, its generality remains limited by the intrinsic trade‐offs in existing photosensitizers (PSs). Noble metal (e.g., Ir, Ru) complexes offer high efficiency yet suffer from cost and sustainability concerns, while organic carbonyl sensitizers suffer from weak visible‐light absorption and short‐lived triplet states. Herein, we report heavy‐atom‐free organic PSs featuring a multi‐channel through‐space charge transfer (TSCT) architecture within a thermally activated delayed fluorescence (TADF) framework. A highly twisted donor‐acceptor topology enforces near‐complete frontier orbital separation, leading to ultralow singlet‐triplet energy gaps (Δ E _ST down to 0.013 eV) and thereby enabling efficient spin interconversion. Consequently, these PSs simultaneously achieve high intersystem crossing (ISC) quantum yields, microsecond‐scale triplet lifetimes, and high triplet energies ( E _T up to 63.7 kcal mol ⁻¹ ), rivaling those of state‐of‐the‐art noble‐metal systems. Leveraging these features, we demonstrate the first visible‐light‐driven intermolecular [2 + 2] cycloaddition of 1,3‐diphenylphosphindole 1‐oxides with alkenes and alkynes, enabling rapid access to structurally complex cyclobutane‐fused phosphindole 3‐oxides that hold potential value in drug screening but are typically difficult to obtain. Mechanistic studies support a TEnT pathway, in which minimal Δ E _ST and efficient ISC are key to achieving high TEnT reactivity.

The photoinitiating system is a decisive factor governing the speed, resolution, and operational robustness of digital light processing (DLP) 3D printing. However, most existing systems rely on inert atmospheres, high irradiation intensities, or prolonged exposure times, severely limiting printing efficiency and practical applicability. Here we report a molecular design paradigm that fundamentally redefines the functional role of multiple‐resonance thermally activated delayed fluorescence (MR‐TADF) materials, transforming them from efficient light emitters into highly active triplet photocatalysts through selenium‐atom engineering. By integrating carbonyl‐assisted n–π*/π–π* state coupling with selenium‐induced spin‐orbit enhancement, the resulting photocatalyst QPSO achieves a near‐unity intersystem crossing quantum yield together with an exceptionally large forward‐to‐reverse intersystem crossing rate constant ratio, thus efficiently channeling exciton flux into long‐lived, redox‐active triplet states. When combined with a hypervalent iodonium co‐initiator, this system enables rapid photopolymerization in ambient air using low‐intensity blue light. As a result, single‐layer curing is completed within only 1.5–2 s across a broad thickness range, affording a printing resolution down to 10 µm and a record‐high build speed of up to 72 cm h ⁻¹ at 400 µm layer thickness. The platform supports the fabrication of complex hierarchical architectures while exhibiting excellent biocompatibility.

The photoinitiating system is a decisive factor governing the speed, resolution, and operational robustness of digital light processing (DLP) 3D printing. However, most existing systems rely on inert atmospheres, high irradiation intensities, or prolonged exposure times, severely limiting printing efficiency and practical applicability. Here we report a molecular design paradigm that fundamentally redefines the functional role of multiple‐resonance thermally activated delayed fluorescence (MR‐TADF) materials, transforming them from efficient light emitters into highly active triplet photocatalysts through selenium‐atom engineering. By integrating carbonyl‐assisted n–π*/π–π* state coupling with selenium‐induced spin‐orbit enhancement, the resulting photocatalyst QPSO achieves a near‐unity intersystem crossing quantum yield together with an exceptionally large forward‐to‐reverse intersystem crossing rate constant ratio, thus efficiently channeling exciton flux into long‐lived, redox‐active triplet states. When combined with a hypervalent iodonium co‐initiator, this system enables rapid photopolymerization in ambient air using low‐intensity blue light. As a result, single‐layer curing is completed within only 1.5–2 s across a broad thickness range, affording a printing resolution down to 10 µm and a record‐high build speed of up to 72 cm h ⁻¹ at 400 µm layer thickness. The platform supports the fabrication of complex hierarchical architectures while exhibiting excellent biocompatibility.

Visible‐light‐driven polymerization offers unparalleled spatiotemporal control and energy efficiency, yet its practical performance is fundamentally constrained by the excited‐state dynamics of the photosensitizer. In this study, we report a class of ortho ‐positioned multi‐donor–acceptor molecules featuring multichannel through‐space charge transfer (TSCT) characteristics as highly efficient, heavy‐atom‐free triplet photosensitizers. By constructing a highly twisted three‐dimensional (3D) charge‐transfer network, these molecules achieve exceptional photophysical performance, including high intersystem crossing (ISC) quantum yields ( Φ _ISC up to 0.86), microsecond‐scale triplet lifetimes, and an extraordinarily small singlet‐triplet energy gap (Δ E _ST as low as 0.008 eV), while maintaining high triplet energies and strong visible‐light absorption. Benefiting from these attributes, the TSCT photosensitizers efficiently activate diphenyl ketone benzoyl oxime ester coinitiators via a triplet‐triplet energy transfer (TTEnT) mechanism, enabling rapid and well‐controlled acrylate polymerization under low‐intensity visible‐light irradiation. Importantly, this strategy enables, for the first time, the application of multichannel TSCT photosensitizers in digital light processing (DLP) 3D printing, allowing high‐resolution fabrication of complex 3D architectures under ambient conditions with excellent operational robustness and biocompatibility. This work establishes a versatile molecular platform for the rational design of organic triplet photosensitizers and advances visible‐light‐based precision manufacturing technologies.

Visible‐light‐driven polymerization offers unparalleled spatiotemporal control and energy efficiency, yet its practical performance is fundamentally constrained by the excited‐state dynamics of the photosensitizer. In this study, we report a class of ortho ‐positioned multi‐donor–acceptor molecules featuring multichannel through‐space charge transfer (TSCT) characteristics as highly efficient, heavy‐atom‐free triplet photosensitizers. By constructing a highly twisted three‐dimensional (3D) charge‐transfer network, these molecules achieve exceptional photophysical performance, including high intersystem crossing (ISC) quantum yields ( Φ _ISC up to 0.86), microsecond‐scale triplet lifetimes, and an extraordinarily small singlet‐triplet energy gap (Δ E _ST as low as 0.008 eV), while maintaining high triplet energies and strong visible‐light absorption. Benefiting from these attributes, the TSCT photosensitizers efficiently activate diphenyl ketone benzoyl oxime ester coinitiators via a triplet‐triplet energy transfer (TTEnT) mechanism, enabling rapid and well‐controlled acrylate polymerization under low‐intensity visible‐light irradiation. Importantly, this strategy enables, for the first time, the application of multichannel TSCT photosensitizers in digital light processing (DLP) 3D printing, allowing high‐resolution fabrication of complex 3D architectures under ambient conditions with excellent operational robustness and biocompatibility. This work establishes a versatile molecular platform for the rational design of organic triplet photosensitizers and advances visible‐light‐based precision manufacturing technologies.

Molecular nanocarbons are critical bridges between small polycyclic aromatic hydrocarbons and extended graphene lattices, driving advances across materials science, optoelectronics, and quantum technologies. However, the atomically precise synthesis of such systems, particularly those featuring K-region and cove-type topologies, remains an enduring challenge. Here, we present a de novo modular strategy that overcomes this constraint by directing K-region growth via annulation of preorganized aryl acetylnaphthalene precursors with acetylenedicarboxylate. The strategy mirrors the hierarchical construction of pyrene by formally inserting naphthalene fragments into spatially defined molecular scaffolds. This method integrates Suzuki-Miyaura coupling with a Zn(OTf)₂-catalyzed cascade comprising Friedel-Crafts alkylation, dehydro-Diels-Alder cycloaddition, and dehydrogenative aromatization. The platform affords structurally diverse pyrene-based molecular nanocarbons with programmable control over topology and dimensionality, spanning linear, contorted, and three-dimensional π-architectures. These results establish a generalizable blueprint for bottom-up synthesis of complex carbon-rich architectures with atomic precision.

Iridium(III) complexes play a prominent role in organometallic chemistry, with significant research efforts directed toward Cp*Ir(III) species, broadly categorized into cyclic and acyclic types. Although studies on these two classes began roughly simultaneously, the development of acyclic Cp*Ir(III) complexes has lagged significantly behind their cyclic counterparts. Herein, we report a general and efficient strategy for synthesizing various persistent aryl Cp*Ir(III)(CO)Cl complexes directly from aryl aldehydes, with in situ generated CO as a stabilizing ligand. These acyclic Cp*Ir(III) complexes showcase exceptional reactivity, undergoing reactions with up to eight classes of nucleophiles to generate diverse diorganoiridium(III) species with remarkable stability. Electrochemical analysis of these complexes provides insights into their reductive elimination processes. Guided by these findings, Cp*Ir(III)-mediated decarbonylative C–C and C–O cross-couplings of aryl aldehydes are successfully developed. This study establishes a robust platform for the exploration of acyclic Cp*Ir(III) complexes, paving the way for further advancements in iridium(III) chemistry.

Acenaphthylene-containing polycyclic aromatic hydrocarbons (AN-PAHs) are noteworthy structural motifs for organic functional materials due to their non-alternant electronic structure, which increases electron affinity. However, the synthesis of AN-PAHs has traditionally required multiple sequential synthetic steps, limiting structural diversity. Herein, we present a tandem C−H penta- and hexaannulation reaction of aryl alkyl ketone with acetylenedicarboxylate. This integrated approach enhances overall efficiency and selectivity, marking a significant advancement in AN-PAH synthesis. Mechanistic studies unveil an orchestrated extension of five- and six-membered rings through C−H activation-annulation and Diels–Alder reaction. Additionally, the tandem annulation reaction can be performed stepwise, further validating the proposed mechanism and increasing the structural diversity of AN-PAHs.

Efficient and streamlined synthetic methods that facilitate the rapid build-up of structurally diverse π-conjugated systems are of paramount importance in the quest for organic optoelectronic materials. Among these methods, transition-metal-catalyzed oxidative Ar-H/Ar-H coupling reactions between two (hetero)arenes have emerged as a concise and effective approach for generating a wide array of bi(hetero)aryl and fused heteroaryl structures. This innovative approach bypasses challenges associated with substrate pre-activation processes, thereby allowing for the creation of frameworks that were previously beyond reach using conventional Ar-X/Ar-M coupling reactions. These inherent advantages have ushered in new design patterns for organic optoelectronic molecules that deviate from traditional methods. This ground-breaking approach enables the transcendence of the limitations of repetitive material structures, ultimately leading to the discovery of novel high-performance materials. In this Perspective, we provide an overview of recent advances in the development of organic optoelectronic materials through the utilization of transition-metal-catalyzed oxidative Ar-H/Ar-H coupling reactions. We introduce several notable synthetic strategies in this domain, covering both directed and non-directed oxidative Ar-H/Ar-H coupling strategies, dual chelation-assisted strategy and directed ortho-C-H arylation/cyclization strategy. Additionally, we shed light on the role of oxidative Ar-H/Ar-H coupling reactions in the advancement of high-performance organic optoelectronic materials. Finally, we discuss the current limitations of existing protocols and offer insights into the future prospects for this field.