Dimensionality Mediated Highly Repeatable and Fast Transformation of Coordination Polymer Single Crystals for All-Optical Data Processing.

A family of coordination polymers (CPs) based on dynamic structural elements are of great fundamental and commercial interest addressing modern problems in controlled molecular separation, catalysis, and even data processing. Herein, the endurance and fast structural dynamics of such materials at ambient conditions are still a fundamental challenge. Here, we report on the design of a series of Cu-based CPs [Cu(bImB)Cl2] and [Cu(bImB)2Cl2] with flexible ligand bImB (1,4-bis(imidazol-1-yl)butane) packed into one- and two-dimensional (1D, 2D) structures demonstrating dimensionality mediated flexibility and reversible structural transformations. Using the laser pulses as a fast source of activation energy, we initiate CP heating followed by anisotropic thermal expansion and 0.2-0.8% volume changes with the record transformation rates from 2220 to 1640 s-1 for 1D and 2D CPs, respectively. The endurance over 103 cycles of structural transformations, achieved for the CPs at ambient conditions, allows demonstrating optical fiber integrated all-optical data processing.

Photochromic Free MOF-Based Near-Infrared Optical Switch.

We demonstrate herein an all-optical switch based on stimuli-responsive and photochromic-free metal-organic framework (HKUST-1). Ultrafast near-infrared laser pulses stimulate a reversible 0.4 eV blue shift of the absorption band with up to 200 s-1 rate due to dehydration and concomitant shrinking of the structure-forming [Cu2 C4 O8 ] cages of HKUST-1. Such light-induced switching enables the remote modulation of intensities of photoluminescence of single crystals of HKUST-1 as well visible radiation passing through the crystal by 2 order of magnitude. This opens up the possibility of utilyzing stimuli-responsive MOFs for all-optical data processing devices.

Metal-mediated tunability of MOF-based optical modulators.

We report on the design of 1D MOFs based on a nopinane-annelated organic ligand and Co(II) or Ni(II), the variation of which allows tuning the optical modulation bandwidth. Structural and time-resolved analysis revealed the optical modulation mechanism, the rates and its endurance, thereby enriching the list of sustainable MOFs for tunable optical modulators.

Laser-Assisted Design of MOF-Derivative Platforms from Nano- to Centimeter Scales for Photonic and Catalytic Applications.

Laser conversion of metal-organic frameworks (MOFs) has recently emerged as a fast and low-energy consumptive approach to create scalable MOF derivatives for catalysis, energy, and optics. However, due to the virtually unlimited MOF structures and tunable laser parameters, the results of their interaction are unpredictable and poorly controlled. Here, we experimentally base a general approach to create nano- to centimeter-scale MOF derivatives with the desired nonlinear optical and catalytic properties. Five three- and two-dimensional MOFs, differing in chemical composition, topology, and thermal resistance, have been selected as precursors. Tuning the laser parameters (i.e., pulse duration from fs to ns and repetition rate from kHz to MHz), we switch between ultrafast nonthermal destruction and thermal decomposition of MOFs. We have established that regardless of the chemical composition and MOF topology, the tuning of the laser parameters allows obtaining a series of structurally different derivatives, and the transition from femtosecond to nanosecond laser regimes ensures the scaling of the derivatives from nano- to centimeter scales. Herein, the thermal resistance of MOFs affects the structure and chemical composition of the resulting derivatives. Finally, we outline the "laser parameters versus MOF structure" space, in which one can create the desired and scalable platforms with nonlinear optical properties from photoluminescence to light control and enhanced catalytic activity.

Light-Induced Color Switching of Single Metal-Organic Framework Nanocrystals.

Photoinduced modulation of the optical parameters of nanomaterials underlies the operating principles of all-optical nanodevices. Here, we demonstrate the laser-induced 10% modulation of the refractive index and 16-fold modulation of the extinction coefficient of the dynamic metal-organic framework (HKUST-1) nanocrystals within the whole visible range. Using the laser-induced water sorption/desorption process inside HKUST-1, we have achieved size-dependent reversible tuning of brightness and color of its nanocrystals over the different spatial directions and color palette. The numerical analysis also confirmed the detected optical tuning through the evolution of optical spectra and directivity of the scattered light. The results of the work demonstrate the promising nature of the dynamic metal-organic frameworks for nonlinear optics and expand the library of chemically synthesized hybrid materials with light-controlled optical properties.

Single Particle Color Switching by Laser-Induced Deformation of Liquid Metal-derived Microcapsules.

Active controlling of optical properties of metallic particles holds great promise for nonlinear nanophotonics and compact optoelectronic devices. Except for the electronic and chemical tuning of their properties, active control through fast and reversible shape modulation remains a significant challenge. Here, we report on the concept for changing the color and brightness of single particles by reversible/irreversible tuning of their shapes. As a family of plasmonic materials with low melting points and high flexibility, we synthesized liquid metal microparticles with different interior (dense/hollow) and morphology from Ga and its alloys (GaNi, GaCu). Utilizing near-infrared femtosecond laser pulses, we achieve two regimes for reversible/irreversible optical tuning due to consequent weak/strong perturbation of the microcapsules (MC) shapes. The chemical composition and MCs morphology significantly affect the tuning of color and brightness, as well as the rigidity of the MCs to extreme laser conditions.

Polymer Matrix Incorporated with ZIF-8 for Application in Nonlinear Optics.

Polymers with embedded metal-organic frameworks (MOFs) have been of interest in research for advanced applications in gas separation, catalysis and sensing due to their high porosity and chemical selectivity. In this study, we utilize specific MOFs with high thermal stability and non-centrosymmetric crystal structures (zeolitic imidazolate framework, ZIF-8) in order to give an example of MOF-polymer composite applications in nonlinear optics. The synthesized MOF-based polymethyl methacrylate (PMMA) composite (ZIF-8-PMMA) demonstrates the possibility of the visualization of near-infrared laser beams in the research lab. The resulting ZIF-8-PMMA composite is exposed to a laser under extreme conditions and exhibits enhanced operating limits, much higher than that of the widely used inorganic materials in optics. Overall, our findings support the utilization of MOFs for synthesis of functional composites for optical application.