Pei Nian Liu

Conventional structural designs of proton exchange membranes often fail to decouple ion transport efficiency from the adverse effects of dense polymer chain packing. Consequently, achieving a balance among high proton conductivity, favorable dimensional stability, and superior mechanical toughness remains a formidable challenge. In this study, we present a strategic approach to manipulate the segmental distribution of polycarbazole-based proton exchange membranes by exploiting the positional isomerism of phenyl substitution, thereby promoting the formation of free volume and microphase-separated morphologies. Two isomeric polymers, S-PEM-100 (featuring a rigid linear backbone) and T-PEM-100 (featuring a rigid twisted backbone), were synthesized via superacid-catalyzed polycondensation. Molecular dynamics simulations and CO2 adsorption–desorption measurements revealed that the twisted geometry of T-PEM-100 hinders dense interchain packing, leading to a substantially increased free volume, whereas S-PEM-100 retains compact π–π stacking. Small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), and transmission electron microscopy (TEM) confirmed that this enlarged free volume facilitates the self-assembly of sulfonic acid groups into large, well-connected hydrophilic domains. Consequently, T-PEM-100 achieved a high proton conductivity of 166.9 mS cm–1 at 80 °C and exhibited outstanding performance in both pure water electrolysis and H2/O2 fuel cells. This work provides fundamental insights into leveraging molecular geometry for the design of high-performance proton exchange membranes for sustainable energy applications.

Poly(ADP-ribose) polymerase (PARP) inhibitors have achieved clinical success in BRCA-mutated triple-negative breast cancer (TNBC), while their clinical utility remains limited in BRCA wild-type (WT) tumors. Co-targeting of PARP and other oncogenic signaling pathways represents an effective strategy to broaden the therapeutic applicability of PARP inhibitors in TNBC patients. Herein, we identified dual PARP/GPX4 inhibitors via a structure-based hybridization strategy and explored the dual-target antitumor effect in blocking the progression of TNBC. We found that compound 12 exhibited potent biochemical inhibitory activities against both PARP and GPX4. In both BRCA-mutated and BRCA-WT TNBC cells, compound 12 exerts superior antitumor efficacy by exerting a dual impact on DNA damage and ferroptosis induction. In both HCC1937 and MDA-MB-231 xenografts, compound 12 exhibited potent in vivo antitumor activity with efficacy superior to both single agents and combined treatment. Our findings highlight the potential of dual PARP/GPX4 inhibitors in overcoming the limitations of PARP inhibitors in anti-TNBC.

Quantum spin rings represent fundamental model systems that exhibit distinctive quantum phenomena arising from their periodic boundary conditions and enhanced quantum fluctuations. Here, we report the on‐surface synthesis and atomic‐scale characterization of antiferromagnetic S = 1/2 quantum spin rings composed of pristine [2]triangulene units on Au(111). Using stepwise on‐surface synthesis followed by scanning tunneling microscopy tip‐induced dehydrogenation, we precisely constructed cyclic five‐ and six‐membered spin rings and investigated their spin states via scanning probe microscopy and multireference calculations. Bond‐resolved noncontact atomic force microscopy imaging reveals that the six‐membered ring retains a planar geometry, whereas the five‐membered ring exhibits pronounced structural distortion. The six‐membered ring hosts a uniform excitation gap that can be accurately described by a Heisenberg spin model and multireference CASCI calculations. In contrast, although an ideal C ₅ ‐symmetric pentamer is theoretically expected to host a degenerate, frustrated ground state, the experimentally realized five‐membered ring is structurally distorted, which lifts this degeneracy and produces asymmetric spatial distributions of the spin ground state. Our findings establish a versatile molecular platform for exploring correlated magnetism and quantum spin phenomena in cyclic organic magnetic architectures.

Quantum spin rings represent fundamental model systems that exhibit distinctive quantum phenomena arising from their periodic boundary conditions and enhanced quantum fluctuations. Here, we report the on‐surface synthesis and atomic‐scale characterization of antiferromagnetic S = 1/2 quantum spin rings composed of pristine [2]triangulene units on Au(111). Using stepwise on‐surface synthesis followed by scanning tunneling microscopy tip‐induced dehydrogenation, we precisely constructed cyclic five‐ and six‐membered spin rings and investigated their spin states via scanning probe microscopy and multireference calculations. Bond‐resolved noncontact atomic force microscopy imaging reveals that the six‐membered ring retains a planar geometry, whereas the five‐membered ring exhibits pronounced structural distortion. The six‐membered ring hosts a uniform excitation gap that can be accurately described by a Heisenberg spin model and multireference CASCI calculations. In contrast, although an ideal C ₅ ‐symmetric pentamer is theoretically expected to host a degenerate, frustrated ground state, the experimentally realized five‐membered ring is structurally distorted, which lifts this degeneracy and produces asymmetric spatial distributions of the spin ground state. Our findings establish a versatile molecular platform for exploring correlated magnetism and quantum spin phenomena in cyclic organic magnetic architectures.

Piezoelectric dynamic therapy utilizes the acoustic-electric conversion of piezoelectric materials under ultrasound (US) to generate abundant reactive oxygen species (ROS) to kill tumor cells, offering an attractive protocol for tumor therapy. However, traditional piezoelectric sonosensitizers generally exhibit wide band gaps, resulting in suboptimal charge separation, low ROS generation efficiency, and insufficient induction of immunogenic cell death (ICD), which limits their therapeutic efficacy. In this study, we report a narrow-band gap piezoelectric nanoplatform engineered from porphyrin-osmapentalyne hybrids (P-OsPT). By strategically coupling anti-Hückel carbolong electron acceptor (A) with a Hückel-compliant porphyrin electron donor (D), a pronounced A-D-A architecture is established. The incorporation of osmium within the carbolong framework facilitates a d_π-p_π conjugation system, which not only significantly narrows the band gap and provides efficient channels for intraparticle charge transport but also imparts piezoelectric properties to the material. Under US irradiation, P-OsPT nanoparticles (NPs) achieve efficient acoustic-electric conversion, resulting in high ROS generation efficiency. In vitro and in vivo studies demonstrate that P-OsPT NPs-mediated piezoelectric immunotherapy can effectively kill tumor cells while inducing ICD, resulting in activation of immune response and inhibition of tumor metastasis. This study highlights the potential of carbolong complexes as a versatile platform for piezoelectric immunotherapy.

Microneedle (MN) patches have emerged as a highly efficient platform for localized drug delivery, showing great promise in cancer therapy due to their ability to enable precise drug administration. However, conventional MN systems are limited by the low drug-loading capacity of their tips and primarily rely on biologically inert, nontherapeutic matrices for structural support, which restricts further gains in antitumor efficacy. Herein, we present a strategy turning toxicity into therapy by constructing palladium nanoparticle-loaded poly(vinyl alcohol)/polyethylenimine (PVA/PEI@Pd) hydrogel microneedles (PPPd-MNs), which exploit the intrinsic cytotoxicity of PEI for synergistic melanoma therapy. The PPPd-MNs efficiently catalyze the deprotection of a doxorubicin prodrug (P-DOX), enabling in situ generation of active doxorubicin (DOX). Notably, the PEI matrix serves a dual function: acting as a robust ligand to stabilize Pd catalysts and functioning as a therapeutic agent that disrupts cancer cell membranes. Both in vitro and in vivo experiments demonstrate that the combination of Pd-mediated bioorthogonal activation of DOX and PEI-induced membrane damage achieves a remarkable synergistic therapeutic outcome in a murine melanoma model, resulting in a tumor inhibition rate of up to 98%. This work repurposes the inherent cytotoxicity of the carrier material as an active therapeutic component, offering a novel paradigm for the design of high-performance bioorthogonal catalytic systems.

Ferromagnetic Heisenberg spin-1/2 chains represent a fundamental model of quantum magnetism, supporting collective spin-wave excitations that govern coherent spin dynamics and transport in one dimension. However, the realization of ferromagnetic organic spin chains with chemically programmable interactions remains largely unexplored. Here we encode ferromagnetic Heisenberg spin-1/2 chains within a carbon-based molecular architecture. Using open-shell [2]triangulene as a chemically defined spin-1/2 building block, we combine on-surface synthesis with site-selective scanning tunneling microscope tip–induced transformations to construct designer chains on Au(111) with spin-by-spin control. Real-space spectroscopic measurements correlate atomic structure with collective magnetic behavior, revealing signatures consistent with ferromagnetic exchange and finite-size spin-wave excitations. These results establish a chemically controlled realization of ferromagnetic quantum spin chains in a purely π-conjugated carbon framework.

Recent advances in scanning tunneling microscopy (STM) manipulation have enabled atomic/molecular-scale fabrication of artificial quantum structures, yet scalability remains a critical challenge. Here we introduce single-molecule lithography (SML), a strategy that integrates a reinforcement-learning algorithm with STM manipulation, to achieve programmable lattices of molecular radicals. We developed an AI agent to autonomously execute tip-induced dehydrogenation of triphenylmethyl (TPM) molecules in TPM-based metal–organic frameworks self-assembled on a Au(111) substrate. Guided by the AI-optimized operating parameters, we constructed triangular, Kagome, and honeycomb lattices of molecular radicals in Fe–TPM and Ni–TPM platforms. Furthermore, we applied fully automatic SML to fabricate a 632-site triangular lattice as well as structures with programmable shape and size. These results demonstrate that the AI-driven SML provides a promising path toward programmable fabrication of artificial quantum matters.

On-surface synthesis provides a powerful strategy for the atomically precise fabrication of low-dimensional nanoscale structures. However, controlling on-surface reaction pathways remains a challenge because of the irreversible and poorly selective nature of covalent coupling. Here, we report the direct transformation from isocyanides to cumulenes via the in situ formation of organometallic templates on Ag(110) and achieve the synthesis of two cumulene-containing organometallic polymers: chains (CC-OMCs) and networks (CC-OMNs). Using a bifunctional precursor 1,4-dibromo-2,5-diisocyanobenzene (DBDICB), the surface-assisted debromination performed the organometallic chain templates with heterotactic (hetero-OMCs) and homotactic (homo-OMCs) arrangement configurations between neighboring dehalogenated molecular units. The individual hetero-OMCs underwent intrachain polymerization to form the CC-OMCs. In contrast, increasing the coverage of DBDICB on Ag(110) drove the formation of 2D assembled structures of homo-OMCs by electrostatic interactions, thereby further promoting interchain polymerization to form CC-OMNs.