Abstract Structural colors generated by photonic crystals (PCs) have attracted interest in optical sensing. However, the sensing behavior of porous PCs is commonly tailored through material composition, pore structure, or surface chemistry. Here, we show that the spatial configuration of sequence-switchable MOF-on-MOF Bragg stacks regulates molecular access and adsorption while preserving the constituent metal–organic frameworks (MOFs). The reflection wavelength is continuously tuned across the visible spectrum by controlling layer thickness and refractive-index contrast, producing blue-to-red structural colors with a peak reflectance of approximately 90%. Reversing the layer sequence generates distinct optical response amplitudes and kinetics toward volatile organic compounds (VOCs). Combined optical analysis and molecular dynamics simulations further show that the sensing responses depend not only on molecular uptake but also on spatial adsorption distribution and framework–guest interactions. These findings establish molecular transport pathway control through spatial configuration as an additional strategy for regulating the sensing behavior of porous photonic materials.
Abstract Antiferromagnetic spintronics promises ultrafast device performance, yet the essential Néel vector reversal is hindered by its intrinsic immunity to external magnetic fields. Here, we propose a mechanism for deterministic Néel vector reversal in 2D van der Waals antiferromagnets enabled by ultrafast laser pulses. The core physics involves light-induced asymmetric interlayer demagnetization, which drives the antiferromagnet into a transient ferrimagnetic state with a finite net moment. This transient symmetry breaking allows the Néel vector to be controlled by an external magnetic field. We identify that the intrinsic structural and electronic asymmetries and spin–orbit-coupling mediated spin flips are essential for this process. Using first-principles calculations and real-time time-dependent density functional theory, we further demonstrate this mechanism in bilayer NiICl and YI2. Our work establishes a general strategy for the optical manipulation of 2D antiferromagnetic order.
Abstract TADF-sensitized fluorescence (TSF), also known as hyperfluorescence, combines efficient triplet exciton harvesting with the narrowband emission of fluorescent emitters. Yet, its performance depends on the interplay between exciton conversion, energy transfer, and molecular organization across different length scales. Herein, we review recent progress in nanoscale exciton-transfer engineering for TSF, with emphasis on molecular excited-state dynamics, sensitizer-dopant spatial control, diversified energy-transfer pathways, and interlayer sensitization. These approaches regulate exciton conversion and lifetime, balance Förster and Dexter energy transfer, and control exciton distribution within emissive layers and across interfaces. We also discuss emerging directions including kinetic matching, spatial organization, and multiscale modeling for understanding the links between molecular structure, energy-transfer dynamics, and device performance. This Mini-Review provides profound insights into transforming random blend systems into controllable nanoscale exciton-transfer networks, paving the way for efficient narrowband TSF OLEDs.
Abstract Applications of plasmonic nanopores for molecular sequencing remain limited by poorly controlled translocation dynamics and predominantly single-pass readout. Here, we propose an in-plane heterostructure architecture that integrates molecular transport, confinement, and surface-enhanced Raman scattering (SERS) readout to enable deterministic and repeated interrogation of individual biomolecules. Using all-atom molecular dynamics coupled with nanoplasmonic simulations, we show that the heterostructure can actively guide molecules into and through a localized sensing region while constraining their conformational and translational dynamics. Simulated SERS signatures discriminate single-stranded DNA sequences with resolution approaching the single-nucleobase scale and further suggest the feasibility of distinguishing polyglutamine tracts of different lengths. Importantly, the in-plane geometry allows molecules to be controllably transported back and forth across the sensing region, providing a route to repeated measurements of the same molecule rather than relying on stochastic single-pass translocation. These results suggest a strategy for improving the accuracy and reproducibility of nanopore-based biomolecular sensing.
Abstract Mechanically interlocked networks (MINs) built from [2]rotaxane cross-linkers combine high extensibility with enhanced toughness, yet how the interplay between ring mobility and bond scission influences their mechanical responses remains unclear. Here, we employ coarse-grained molecular dynamics simulations to investigate the deformation mechanisms of MINs with varying bond strength, strain rate, and graft density, where a crossover is observed in the deformation mechanism as bond strength increases. Specifically, the weak cross-links lead to scission-dominated deformation with negligible ring sliding, whereas MINs with strong cross-links exhibit profound ring sliding and inhibited bond scission, contributing to the enhanced toughness. Moreover, bond scission and ring sliding exhibit a strain-rate response with the lowest rate favoring scission over sliding, while reducing graft density delays the onset of both processes. These findings provide molecular insights for optimizing MIN mechanics by balancing movable-junction dynamics and cross-link stability.
