Herein, we demonstrated a steric-hindrance-controlled laser switch in pure metal−organic framework (MOF) microcrystals. The well-faceted MOF microwires with aggregation-induced emission (AIE) lumnogens as linkers function as typical Fabry−Peŕot microlasers. The steric hindrance around the AIE linkers can be reduced by the loss of guest molecules, which lead to the enhanced rotation of linkers with red-shifted gain behavior. On this basis, the gain region was readily switched through changing the steric hindrance via the desorption/adsorption of guests. As a result, the reversible switching of the dual-wavelength lasing from MOF microwires was achieved. The results provide a promising route to the development of versatile micro-/nanolasers with desired applications.

Porous organic frameworks have emerged as the promising platforms to construct tunable microlasers. Most of these microlasers are achieved from metal–organic frameworks via meticulously accommodating the laser dyes with the sacrifice of the pore space, yet they often suffer from the obstacles of either relatively limited gain concentration or sophisticated fabrication techniques. Herein, we reported on the first hydrogen-bonded organic framework (HOF) microlasers with color-tunable performance based on conformation-dependent stimulated emissions. Two types of HOF microcrystals with the same gain lumnogen as the building block were synthesized via a temperature-controlled self-assembly method. The distinct frameworks offer different conformations of the gain building block, which lead to great impacts on their conjugation degrees and excited-state processes, resulting in remarkably distinct emission colors (blue and green). Accordingly, blue/green-color lasing actions were achieved in these two types of HOFs based on well-faceted assembled wire-like cavities. These results offer a deep insight on the exploitation of HOF-based miniaturized lasers with desired nanophotonics performances.

Porous organic materials (POMs) have shown great potential for fabricating tunable miniaturized lasers. However, most pure-POM micro/nanolasers are achieved via coordination interactions, during which strong charge exchanges inevitably destroy the intrinsic gain property and even lead to optical quenching, hindering their practical applications. Herein, we reported on an approach to realize hydrogen-bonded organic framework (HOF)-based in situ wavelength-switchable lasing based on the framework-shrinkage effect. A flexible HOF with reversible framework shrinkage was constructed from gain blocks with multiple rotors. The framework shrinkage of the HOF induced the in situ regulation on the conformation and conjugation degree of gain blocks, leading to distinct energy-level structures with blue/green-color gain emissions. Inspired by this, the in situ wavelength-switchable lasing from HOF microcrystals was achieved through reversibly controlling the framework shrinkage via the absorption/desorption of guests. The results offer useful insight into the use of flexible HOFs for exploiting miniaturized lasers with on-demand nanophotonics performance.

Metal−organic frameworks (MOFs) are an emerging kind of laser material, yet they remain a challenge in the controlled fabrication of crystal nanostructures with desired morphology for tuning their optical microcavities. Herein, the shape-engineering of pure MOF microlasers was demonstrated based on the coordination-mode-tailored method. The one-dimensional (1D) microwires and 2D microplates were selectively fabricated through changing the HCl concentration to tailor the coordination modes. Both the single-crystalline microwires and microplates with strong optical confinement functioned as low-threshold MOF microlasers. Moreover, distinct lasing behaviors of 1D and 2D MOF microcrystals confirm a typical shape-dependent microcavity effect: 1D microwires serve as Fabry−Peŕot (FP) resonators, and 2D microplates lead to the whispering-gallerymode (WGM) microcavities. These results provide a special pathway for the exploitation of MOF-based micro/nanolasers with on-demand functions.

One-dimensional (1D) metal–organic frameworks (MOFs) have shown great potential for designing more sensitive and smart stimuli-responsive photoluminescence metal–organic frameworks (PL-MOFs). Herein, we propose a strategy for constructing the 1D MOFs with tunable stimuli-responsive luminescence regions based on coordination-guided conformational locking. Two flexible 1D MOF microcrystals with trans- and cis-coordination modes, respectively, were synthesized by controlling the spatial constraint of solvents. The two 1D frameworks possess different conformation lockings of gain ligands, which have a great influence on the rotating restrictions and corresponding excited-state behaviors, generating the remarkably distinct color-tunable ranges (cyan-blue to green and cyan-blue to yellow, respectively). On this basis, the two 1D MOF materials, benefiting from the varied stimuli-responsive ranges, have displayed great potential in fulfilling the anticounterfeiting and information encryption applications. These results provide valuable guidance for the development of smart MOF-based stimuli-responsive materials in information identification and data encryption.

The separation of acetylene (C2H2) from carbon dioxide (CO2) is a very important but challenging task due to their similar molecular dimensions and physical properties. In terms of porous adsorbents for this separation, the CO2‐selective porous materials are superior to the C2H2‐selective ones because of the cost‐ and energy‐efficiency but have been rarely achieved. Herein we report our unexpected discovery of the first hydrogen bonded organic framework (HOF) constructed from a simple organic linker 2,4,6‐tri(1H‐pyrazol‐4‐yl)pyridine (PYTPZ) (termed as HOF‐FJU‐88) as the highly CO2‐selective porous material. HOF‐FJU‐88 is a two‐dimensional HOF with a pore pocket of about 7.6 Å. The activated HOF‐FJU‐88 takes up a high amount of CO2 (59.6 cm³ g⁻¹) at ambient conditions with the record IAST selectivity of 1894. Its high performance for the CO2/C2H2 separation has been further confirmed through breakthrough experiments, in‐situdiffuse reflectance infrared spectroscopy and molecular simulations.

Hydrogen-bonded organic frameworks (HOFs) have shown great potential in separation, sensing and host-guest chemistry, however, the pre-design of HOFs remains challenging due to the uncertainty of solvents' participation in framework formation. Herein, the polarity-evolution-controlled framework/luminescence regulation is demonstrated based on multiple-site hydrogen-bonded organic frameworks. Several distinct HOFs were prepared by changing bonding modes of building units via the evolution of electrostatic forces induced by various solvent polarities. High-polar solvents with strong electrostatic attraction to surrounding units showed the tendency to form cage structures, while low-polar solvents with weak electrostatic attraction only occupy hydrogen-bond sites, conducive to the channel formation. Furthermore, the conformation of optical building unit can be adjusted by affecting the solvent polarity, generating different luminescence outputs. These results pave the way for the rational design of ideal HOFs with ondemand framework regulation and luminescence properties.

MOF‐based one‐dimensional materials have received increasing attention in the nanophotonics field, but it is still difficult in the flexible shape evolution of MOF micro/nanocrystals for desired optical functionalities due to the susceptible solvothermal growth process. Herein, we report on the well‐controlled shape evolution of pure‐MOF microcrystals with optical waveguide and lasing performances based on a bottom‐up and top‐down synergistic method. The MOF microcrystals from solvothermal synthesis (bottom‐up) enable the evolution from microrods via microtubes to nanowires through a chelating agent‐assisted etching process (top‐down). The three types of MOF 1D‐microstructures with high crystallinity and smooth surfaces all exhibit efficient optical waveguide performance. Furthermore, MOF nanowire with lowest propagation loss served as low‐threshold pure‐MOF nanolasers with Fabry–Pérot resonance. These results advance the fundamental understanding on the controlled MOF evolution mechanism, and offer a valuable route for the development of pure‐MOF‐based photonic components with desired functionalities.