arXiv subjects

Tongyang Zhao

Publications and source records attributed to Tongyang Zhao.

5 recordsLinked to original sources

arXiv2026

Molecular Curvature Enables Tubular π-Stacked Pathways in Three-Dimensional Conductive Metal-Organic Frameworks

Conductive metal-organic frameworks (MOFs) are commonly constructed from planar aromatic ligands, whose geometries favor conventional π-stacking arrangements. However, intrinsically twisted ligands offer an alternative geometric approach to directing aromatic packing and constructing unconventional framework architectures. Here, we employ intrinsically twisted, butterfly-shaped dibenzo[g,p]chrysene-2,3,6,7,10,11,14,15-octaol (DBC) ligands to construct a series of lanthanide MOFs. Single-crystal X-ray diffraction reveals an interpenetrated three-dimensional framework in which π-π interactions between the aromatic fragments generate axially extended tubular π-stacked pathways, alongside one-dimensional channels rich in hydrogen-bonding sites. Lanthanide substitution preserves the overall tubular framework topology while modulating aromatic stacking distances and local pore environments. PrDBC single crystals exhibit mixed electron-proton transport, with electron and proton conductivities reaching 1.62 x 10-3 and 4.37 x 10-4 S cm-1, respectively, at 338 K and 30% relative humidity. This work highlights molecular curvature as a structural design strategy for constructing three-dimensional conductive MOFs that integrate tubular aromatic stacks with tunable pore environments for mixed electron-proton transport.

cond-mat.mtrl-sci↗

arXiv2026

Programming electronic states in conductive metal-organic frame-works through crystallization-enabled proton management

Conductive metal-organic frameworks (c-MOFs) are promising electronic materials, where electronic states critically determine electrical conductivity. However, achieving controllable modulation of these states during crystallization remains challenging. Existing approaches rely either on redesigning framework components or on introducing external dopants after crystallization, making electronic-state regulation dependent on structural modification or postsynthetic doping. Here, we demonstrate a crystallization-enabled in situ proton-management strategy for regulating the electronic state of c-MOFs. Using Co9HHTP4 as a model system, we show that distinct proton environments influence the balance between competing proton-coupled electron-transfer pathways during Co-O framework assembly while preserving the fundamental framework architecture. HNO3-mediated crystallization produces an electronic state consistent with enhanced electron retention within the Co-O framework and results in a single-crystal conductivity of 8.4 * 10-2 S cm-1, nearly four orders of magnitude higher than Co9HHTP4-NaOAc (1.7 * 10-5 S cm-1), together with a substantially reduced transport activation energy. Hall measurements further reveal a pronounced increase in carrier concentration for Co9HHTP4-HNO3, providing direct evidence that the enhanced conductivity is associated with a substantially increased carrier population. These results establish crystallization conditions as an active parameter for programming electronic states and charge transport in conductive frameworks.

cond-mat.mtrl-sci↗

arXiv2026

Beyond Semantic Narrowing: Robust and Efficient LLM Watermarking with Hamming Neighborhoods

Semantic watermarking improves robustness against watermark removal attacks by embedding detectable signals into sentence-level representations. However, existing watermarking methods typically impose watermark-specific semantic preferences on generated sentences without explicitly accounting for the highly non-uniform and context-dependent semantic preference of LLM generation. When these two preferences are poorly aligned, many natural continuations become incompatible with the watermark, causing semantic narrowing: reduced semantic freedom, increased resampling cost, and potential degradation on tasks with strict semantic requirements. To alleviate this problem, we propose HammingMark, which uses the semantic hash of the preceding sentence as a dynamic center and accepts candidates whose hashes fall within its Hamming neighborhood. Defining watermark validity over a Hamming neighborhood in compact hash space retains a larger fraction of naturally likely semantic continuations. The coarse many-to-one hash mapping further allows diverse semantic realizations to remain watermark-valid. Experiments on C4 and BookSum show that HammingMark achieves strong robustness, high detectability, and near-unwatermarked generation quality, requiring only 2.2 sampled candidates per accepted sentence,a 72.8% reduction compared with the most sampling-efficient existing method. On more complex tasks with strict semantic constraints, HammingMark achieves the highest detection rates with the highest or tied-highest ROUGE-L scores, demonstrating its effectiveness in balancing watermark detectability and generation quality under constrained generation settings.

cs.CR↗

arXiv2026

An encoded asymmetric ligand for metal-selective topological assembly of two-dimensional metal-organic frameworks

Two-dimensional metal-organic frameworks (2D MOFs), with diverse topological architectures, provide a powerful platform for exploring unconventional electronic and lattice-dynamical responses. Yet their structural diversity remains fundamentally constrained by the fixed geometry of high-symmetry ligands. Here, we introduce an encoded asymmetric ligand, benzo[b]triphenylene-2,3,6,7,11,12-hexaol (BTH), for metal-selective topological assembly. By integrating multi-site coordination fields with sterically differentiated environments, BTH exhibits distinct topological programmability: different divalent metal ions direct divergent framework architectures. Specifically, coordination of BTH with divalent Cu(II) and Zn(II) ions assembles Cu-BTH-MOF with a dual-mode hexagonal pore topology and Zn-BTH-MOF with uniform hexagonal channels, respectively, as supported by PXRD Pawley refinement, structural simulations, and pore-size distribution analysis. Furthermore, this topological divergence is accompanied by a significant divergence in charge-transport properties, with Cu-BTH-MOF reaching an electrical conductivity of 1.186 x 10-3 S cm-1, more than six orders of magnitude higher than that of Zn-BTH-MOF (3.38 x 10-10 S cm-1). This work establishes ligand desymmetrization as a programmable strategy for metal-selective topological diversification in 2D MOFs.

cond-mat.mtrl-sci↗

arXiv2026

Soft Responsive Materials Enhance Humanoid Safety

Humanoid robots are envisioned as general-purpose platforms in human-centered environments, yet their deployment is limited by vulnerability to falls and the risks posed by rigid metal-plastic structures to people and surroundings. We introduce a soft-rigid co-design framework that leverages non-Newtonian fluid-based soft responsive materials to enhance humanoid safety. The material remains compliant during normal interaction but rapidly stiffens under impact, absorbing and dissipating fall-induced forces. Physics-based simulations guide protector placement and thickness and enable learning of active fall policies. Applied to a 42 kg life-size humanoid, the protector markedly reduces peak impact and allows repeated falls without hardware damage, including drops from 3 m and tumbles down long staircases. Across diverse scenarios, the approach improves robot robustness and environmental safety. By uniting responsive materials, structural co-design, and learning-based control, this work advances interact-safe, industry-ready humanoid robots.

cs.RO↗