Hongliang Chen

Although catalysis is widely exploited by nature to orchestrate noncovalent supramolecular assembly and build up complex living systems, its utilization in synthetic chemistry has conventionally been limited to accelerating covalent reactions. Consequently, the development of artificial systems for catalytic assembly remains a formidable and largely unexplored challenge. Here, we present a rationally designed strategy of electron-catalyzed supramolecular assembly, wherein the electron acts as an efficient, robust, and versatile catalyst to accelerate the formation of a donor–acceptor complex. Optimization of the elementary steps and intermediate stability yields an efficient catalytic cycle, furnishing the process with both a high turnover number and operational robustness in open air. Furthermore, the electron catalysis can be readily triggered by diverse external stimuli─including electricity, light, and mechanical force─enabling precise spatiotemporal control over the assembly process and near-quantitative synthesis of supramolecular complexes. Collectively, this work establishes a well-elucidated strategy of catalytic assembly with remarkable practicality, advancing the frontiers of noncovalent synthetic chemistry.

Constructing robust, high-conductance gold–carbon (Au–C) contacts remains a central challenge in molecular electronics. The synthesis of stable precursors capable of cleanly forming these highly reactive interfaces is particularly elusive. Here, we exploit N-hydroxyphthalimide (NHP) esters─a versatile class of redox-active esters─for the in situ formation of covalent Au–C(sp3) bonds using scanning tunneling microscope-based break junction (STM-BJ) techniques. Driven by the irreversible expulsion of CO2, which acts as a “thermodynamic spring”, NHP esters undergo single-electron transfer to generate transient carbon radicals that efficiently graft onto Au electrodes. This methodology yields molecular junctions with exceptional stability and ultrahigh conductance approaching the quantum limit of unitary transmission (∼1 G0). By translating abundant carboxylic acid feedstocks into reactive surface anchors, this work establishes NHP esters as a highly effective, sustainable toolkit for the scalable fabrication of high-performance molecular devices.

Molecular switches capable of responding to two or more orthogonal stimuli are essential for advancing molecular-scale logic, sensing, and memory technologies. However, integrating distinct control mechanisms within a single-molecule architecture remains a fundamental challenge. Here, we report a single-molecule electrochemical-mechanical dual-control switch based on difluoroboron dipyrromethene (BODIPY) molecular junctions. We demonstrate that applying an electrochemical gate voltage threshold (−0.6 V) reduces the BODIPY core to a stable radical anion, effectively serving as a logic enable (EN) signal. Under this electrochemically activated regime, precision mechanical modulation (∼5.0 Å amplitude) via an STM tip cleanly dictates the molecular conformation. Compressive strain drives the formation of a highly conductive asymmetric Au–S/Au−π contact (the SET operation) with a two-order-of-magnitude conductance contrast, while tensile strain physically ruptures the Au−π interfacial coupling to recover the symmetric terminal Au–S anchoring (the RESET operation). This dual-input sliding molecular resistor operates stably at frequencies up to 200 Hz, with density functional theory calculations elucidating the underlying radical-enhanced resonant transport pathway. By seamlessly mapping these synergistic electro-mechanical inputs to digital logic, we successfully transform this molecular junction into a nonvolatile, nanoscale gated RS latch. Ultimately, our work establishes a highly robust and versatile design strategy for constructing complex, multistimuli-responsive molecular circuitry at the single-molecule limit.

Two-dimensional polymers (2DPs) have emerged as a class of important materials with the unique advantages of an ultrathin, lightweight nature and a large accessible surface area, showing their promising potential in the area of optoelectronics, energy storage and conversion, and molecular separation. Currently, their synthetic routes mainly rely on two approaches: polymerization coupled with assembly of building blocks, or solid-state crosslinking within preassembled crystals. Herein, we developed a 2D polymerization strategy based on exfoliated 2D molecular crystals (2DMCs), in which crosslinking within individual 2DMCs covalently locks the arrangement of preassembled 2D architecture while maintaining the exfoliated 2D morphology. The monomer is designed with a structure of π-extended rigid cores and multiarm siloxane reactive sites, yielding crystals with lamellar structure. These crystals can be exfoliated into free-standing, well-dispersed 2DMCs with a thickness of 2.2–8.8 nm, and subsequent solid-state crosslinking maintains the 2DMCs into stable 2D architectures, affording organic–inorganic hybrid 2DPs. This process covalently locks their in-plane preassembled structure with long-range π–π stacking, thereby enabling the resulting 2DPs to preserve superstructure-derived functions while exhibiting improved performance and enhanced stability. This work presents a design concept for 2DP synthesis from exfoliated 2DMCs, demonstrating the construction of 2D polymer networks according to preassembled architecture.

Atomic-scale manipulation of chemical bond cleavage and formation offers significant advantages of extending the reaction controllability to the single-molecule regime and enabling the elucidation of fundamental reaction mechanisms. Herein, we drive reactions between two chemical species, open-shell monomeric radicals and closed-shell dimers in single-molecule junctions. Both monomers and dimers form a C−Au covalently linked highly conducting junction in situ, with the conductance being about 100× higher than that of the dimer junction. First-principles calculations suggest that the substitution groups on the carbon in the C(sp³)−Au linkage bond effectively tunes the molecular junction conductance. Notably, captodative radicals enable the formation of weakly bonded spin–spin interactions in solution, yielding diamagnetic dimers, and we can reversibly switch between the dimer and the weakly bonded radical pair by mechanically controlling the gap between the two electrodes.

We report the synthesis of a series of structurally analogous tetrahedral imine cages with controlled variation in the number and position of fluorine atoms. Among these, only the cage (F2) with 12 inwardly directed fluorine atoms exhibits affinity for xenon in both chloroform and tetrachloroethane. Cages lacking fluorine (F0), having outwardly directed fluorine (F3), or featuring rotatable fluorine groups (F1) show negligible binding. These results, combined with cavity volume analysis and theoretical calculation, indicate that Xe-F London dispersion forces and size complementarity are the dominant factors for Xe recognition in solution.

A series of tetrahedral molecular cages were synthesized via imine condensation reactions. Each face features a central triazine core, which imparts an electron-deficient cavity that facilitates anion encapsulation through anion–π interactions.

Atomic-scale manipulation of chemical bond cleavage and formation offers significant advantages of extending the reaction controllability to the single-molecule regime and enabling the elucidation of fundamental reaction mechanisms. Herein, we drive reactions between two chemical species, open-shell monomeric radicals and closed-shell dimers in single-molecule junctions. Both monomers and dimers form a C-Au covalently-linked highly conducting junction in situ, with the conductance about 100 ́ higher than that of the dimer junction. First- principles calculations suggest that the substitution groups on the carbon in the C(sp3)-Au linkage bond effectively tunes the molecular junction conductance. Notably, captodative radicals enable the formation of weakly bonded spin-spin interactions in solution, yielding diamagnetic dimers, and we can reversibly switch between the dimer and the weakly- bonded radical pair by mechanically controlling the gap between the two electrodes.