Shaoqiang Dong

The global (anti)aromaticity of all-benzenoid macrocycles, particularly its modulation by odd-membered size-dependent effects of phenyl units, remains largely unexplored. Herein, we report the synthesis and comprehensive characterization of four macrocycles spanning ring sizes from pentagon to nonagon, incorporating methine and amine units. Single-crystal X-ray analysis reveals that [5]C4N1-BCP adopts a nearly planar π-conjugated structure with significant strain. At low temperatures, [5]C4N1-BCP and its dication [5]C4N1-BCP2+ exhibit 26π-electron global aromatic and 24π-electron global antiaromatic pathways, respectively, in accordance with Hückel’s 4N+2 and 4N rules. In contrast, [7]C4N3-BCP, [8]C4N4-BCP, and [9]C6N3-BCP display predominantly localized aromaticity arising from their highly distorted macrocyclic frameworks, which adopt half-chair, chair, and boat-like conformations, respectively. The tetracation [7]C4N3-BCP4+ exhibits localized aromaticity due to the severe conformational distortions inherent to its odd-membered architecture, as supported by VT NMR spectroscopy. Notably, despite its boat-like conformation, [8]C4N4-BCP4+ displays 40π-electron global antiaromaticity at low temperatures, whereas [9]C6N3-BCP2+ shows 46π-electron global aromaticity under similar conditions. Furthermore, aromatic resonance energy analysis indicates that charge enhances π-electron delocalization across the macrocyclic framework, thereby promoting global ring currents, while the overall degree of global (anti)aromaticity diminishes with increasing macrocyclic size. The systematic pentagon-to-nonagon comparison elucidates the roles of ring size, geometry, and charge state in governing global (anti)aromaticity in all-benzenoid macrocycles, providing deeper insight into the aromaticity and electronic properties of extended π-conjugated macrocyclic molecules and materials.

Fast, stable n‐type organic mixed ionic‐electronic conductors remain scarce. We report a donor glycolated, quinoidal design that facilitates efficient n‐doping and spatially separates hydrophilic side chains from n‐doping sites to preserve electronic pathways. The resulting polymer PQ‐gT, synthesized from a glycolated bithiophene donor and a quinoidal bifuran‐dione acceptor, exhibits high mixed conduction with a figure of merit of µC * = 10.9 F cm ⁻¹ V ⁻¹ s ⁻¹ . In planar accumulation‐mode organic electrochemical transistors (OECTs), it exhibits nearly symmetric sub‐millisecond transients with switching on‐ and off‐times of τ _on / τ _off = 0.5/0.2 ms. These values represent the fastest operation for this type of device architecture. Partial donor replacement with dialkoxybithiazole tunes packing and suppresses swelling, raising µC * to 21.5 F cm ⁻¹ V ⁻¹ s ⁻¹ at 25% substitution, albeit with slower switching. In vertical OECTs, PQ‐gT supports balanced ambipolar operation with ∼1 ms switching and enables a single‐material complementary inverter (gain ≈ 40 V V ⁻¹ at V _IN < 100 mV) that is stable over 10 000 cycles and functional up to 200 Hz. This donor‐glycolated quinoidal strategy furnishes intrinsically fast, aqueous‐stable n‐type organic mixed ionic‐electronic conductors for bioelectronic circuits.

Fast, stable n‐type organic mixed ionic‐electronic conductors remain scarce. We report a donor glycolated, quinoidal design that facilitates efficient n‐doping and spatially separates hydrophilic side chains from n‐doping sites to preserve electronic pathways. The resulting polymer PQ‐gT, synthesized from a glycolated bithiophene donor and a quinoidal bifuran‐dione acceptor, exhibits high mixed conduction with a figure of merit of µC * = 10.9 F cm ⁻¹ V ⁻¹ s ⁻¹ . In planar accumulation‐mode organic electrochemical transistors (OECTs), it exhibits nearly symmetric sub‐millisecond transients with switching on‐ and off‐times of τ _on / τ _off = 0.5/0.2 ms. These values represent the fastest operation for this type of device architecture. Partial donor replacement with dialkoxybithiazole tunes packing and suppresses swelling, raising µC * to 21.5 F cm ⁻¹ V ⁻¹ s ⁻¹ at 25% substitution, albeit with slower switching. In vertical OECTs, PQ‐gT supports balanced ambipolar operation with ∼1 ms switching and enables a single‐material complementary inverter (gain ≈ 40 V V ⁻¹ at V _IN < 100 mV) that is stable over 10 000 cycles and functional up to 200 Hz. This donor‐glycolated quinoidal strategy furnishes intrinsically fast, aqueous‐stable n‐type organic mixed ionic‐electronic conductors for bioelectronic circuits.

We report a novel indene-based allyl radical (ARI-Ph) and three donor-acceptor (D-A) derivatives (DPA-ARI-Ph, ARI-TPA, and ARI-Ph-DPA). Single-crystal X-ray analysis confirms their allyl type structures. Photophysical studies reveal that emission efficiency is governed by vibronic coupling and structural rigidity. ARI-Ph-DPA shows the lowest reorganization energy and minimal overlap between high-frequency vibrations and the charge-transfer pathway. This work presents stable luminescent allyl radicals and offers a design principle for radical emitters.

Photochromic diarylethene molecules are promising candidates for applications in optical data storage devices. However, many reported diarylethene compounds suffer from inefficiencies due to low photocyclization quantum yields or poor fatigue resistance. To address this issue, we have developed a highly efficient boron–nitrogen heterocycle-bridged diarylethene. The bulky boron–nitrogen heterocyclic ethene bridge blocks interconversion between parallel and anti-parallel conformations, yielding two separated rotamers. Evaluation of their photochromic properties demonstrated that the anti-parallel conformer exhibits a high photocyclization quantum yield (Φ_o-c, 89.2%), excellent thermodynamic stability at 298 K and moderate fatigue resistance in hexane. Furthermore, direct comparison with its isosteric carbonaceous analog revealed that incorporating the azaborine moiety into the diarylethene scaffold significantly enhances its photochromic performance. This work presents a strategy that employs azaborine chemistry for the development of potential diarylethene-based photoswitchable materials.

We reported herein a facile synthetic strategy toward the preparation of mono- and di-meta-substituted tris(2,4,6-trichlorophenyl)methyl (TTM) radicals. The di- or tri-anion tris(2,4,6-trichlorophenyl)methane (HTTM) can act as nucleophiles, undergoing nucleophilic reactions to produce mono- and di-meta-substituted HTTM species, regioselectively controlled by the steric hindrance of the central anion. Two more steps give the final meta-substituted monoradicals, exhibiting tunable fluorescent features.

The photophysical mechanisms governing luminescent diradicals, particularly the interplay between their singlet and triplet emissions, remain incompletely understood. Herein, we report three luminescent radicals, monoradical MTA and diradical DTA and DTA(t-Bu)₂, based on a tris(2,4,6-trichlorophenyl)methyl (TTM) scaffold. Experimental results and DFT calculations demonstrated the dual emission mechanism of two diradicaloids with distinct S₁ → S₀ (first excited singlet state to singlet ground state) and T₁ → T₀ (first excited triplet state to triplet ground state) fluorescent radiative pathways, while monoradical MTA shows only doublet emission with a D₁ → D₀ (first excited doublet state to doublet ground state) fluorescent radiative pathway. Varying-temperature electron spin resonance measurements revealed the singlet ground state and thermal accessible triplet ground state of DTA and DTA(t-Bu)₂, with ΔE_S-T values of -0.33 and -0.35 kcal/mol, respectively. Boltzmann population analysis based on the ΔE_S-T values reveals the coexistence of singlet and triplet states at 298 K, with the S₀ state predominating at 63.6% for DTA and 64.4% for DTA(t-Bu)₂, while the corresponding T₀ state populations are 36.4% and 35.6%, respectively. Moreover, two diradicaloids exhibit maximum magnetoluminescence phenomena near 100 K, reflecting the synergistic interplay of thermal energy and magnetic-field-induced S₀ → T₀ spin conversion. Notably, temperature-dependent photoluminescent experiments of two diradicaloids unveiled the dual emission behavior of two diradicaloids: cooling from 298 to 78 K progressively suppressed triplet fluorescence at ∼690 nm while it enhanced weak singlet fluorescence in the near-infrared region beyond 900 nm. External heavy-atom effects of two diradicaloids also demonstrated intramolecular intersystem crossing from T₁ to S₁. Furthermore, theoretical excited-state conformation analysis on two diradicaloids revealed their distinct structural preservation during T₁ → T₀ transitions compared to S₁ → S₀ transitions, which is also confirmed by the smaller reorganization energy, weaker high-frequency vibrations, and smaller radiative transition rate constant. Our work establishes a comprehensive understanding of spin-governed dual fluorescence in TTM diradicaloid systems, providing critical design principles for developing high-spin luminescent materials with tunable spin-controlled emission properties.

Air‐stable luminescent monoradical remains rare. Herein, we report novel stable allyl radicals ( ARS ) achieved by conjugated extension of benzo[ b ]thiophene 1,1‐dioxide and steric protection of 1,3,5‐trichlorobenzene. The reactivity and photophysical properties of these allyl radicals are strongly dependent on protecting groups. Introducing p ‐tolyl group or triphenylamine afforded air‐stable monoradical ARS‐Ph and ARS‐TPA , respectively. ARS‐Ph displays doublet luminescence at 752 nm with negligible photoluminescent quantum yield (PLQY). ARS‐TPA exhibits NIR fluorescence at 860 nm with a PLQY of 11.7%. Whereas, chlorine‐protected ARS‐Cl proved inaccessible, an unsymmetric heterocoupled dimer ARS‐HD was isolated as a luminescent singlet diradicaloid with emission at 790 nm and a PLQY of 0.8%. Natural transition orbital analysis reveals the local excitation nature of ARS‐Ph , excited charge‐transfer characteristics of ARS‐TPA and ARS‐HD . Huang‐Rhys factor and reorganization energy analyses of ARS‐TPA disclose the critical effects of the vibrational decoupling and structure rigidity for its enhanced emission intensity and spectral sharpness. Remarkably, under continuous 365 nm light, ARS‐Ph , ARS‐TPA , and ARS‐HD exhibit excellent luminescent photostability in ambient conditions with half‐lives of 19.7, 42.6, and 21.4 h, respectively. Our study presents a straightforward strategy for developing air‐stable luminescent allyl radicals, expanding the family of luminescent radical materials.

Air‐stable luminescent monoradical remains rare. Herein, we report novel stable allyl radicals ( ARS ) achieved by conjugated extension of benzo[ b ]thiophene 1,1‐dioxide and steric protection of 1,3,5‐trichlorobenzene. The reactivity and photophysical properties of these allyl radicals are strongly dependent on protecting groups. Introducing p ‐tolyl group or triphenylamine afforded air‐stable monoradical ARS‐Ph and ARS‐TPA , respectively. ARS‐Ph displays doublet luminescence at 752 nm with negligible photoluminescent quantum yield (PLQY). ARS‐TPA exhibits NIR fluorescence at 860 nm with a PLQY of 11.7%. Whereas, chlorine‐protected ARS‐Cl proved inaccessible, an unsymmetric heterocoupled dimer ARS‐HD was isolated as a luminescent singlet diradicaloid with emission at 790 nm and a PLQY of 0.8%. Natural transition orbital analysis reveals the local excitation nature of ARS‐Ph , excited charge‐transfer characteristics of ARS‐TPA and ARS‐HD . Huang‐Rhys factor and reorganization energy analyses of ARS‐TPA disclose the critical effects of the vibrational decoupling and structure rigidity for its enhanced emission intensity and spectral sharpness. Remarkably, under continuous 365 nm light, ARS‐Ph , ARS‐TPA , and ARS‐HD exhibit excellent luminescent photostability in ambient conditions with half‐lives of 19.7, 42.6, and 21.4 h, respectively. Our study presents a straightforward strategy for developing air‐stable luminescent allyl radicals, expanding the family of luminescent radical materials.

Incorporating boron atoms into organic macrocycles imparts unique chemical, electronic, and optical properties. The concept of making use of dative boron-nitrogen (B ← N) bonds for the construction of macrocycles has been proposed, but very few examples have been prepared with functional structures, much less pillar-like and other prismatic macrocycles, and their various functionalities have not been fully exploited. Here, we introduce a "functional molecular wall" synthetic protocol based on the self-assembly characteristics of B ← N dative bonds to construct highly symmetrical macrocycles, forming a quasi-pentagonal-shaped macrocycle (named [5]pyBN-p) with a pillar-like structure. Single-crystal analysis confirmed that its structure exhibited a 5-fold symmetric crown-shaped cavity with a diameter of approximately 9.65 Å, forming four sets of three-dimensional channel stacking structures. In solution, thermal cycling between heating and cooling allows for a fast and fully reversible conversion between monomer pyBN-p and pentameric macrocycle [5]pyBN-p. The resultant macrocycle [5]pyBN-p exhibited delayed fluorescence (DF) property and high photoluminescence quantum yield in the solid state. Notably, the supramolecular aggregates of macrocycle [5]pyBN-p possessed permanent porosity and showed an efficient C₂H₆/C₂H₄ inverse separation capacity. This work highlights a new molecular design strategy for B ← N-containing macrocycles, enriching the family of molecular species and expanding new avenues for their applications.