An official website of the United States government
Abstract Photochromic materials with properties that can be dynamically tailored as a function of external stimuli are a rapidly expanding field driven by applications in areas ranging from molecular computing, nanotechnology, or photopharmacology to programable heterogeneous catalysis. Challenges arise, however, when translating the rapid, solution‐like response of stimuli‐responsive moieties to solid‐state materials due to the intermolecular interactions imposed through close molecular packing in bulk solids. As a result, the integration of photochromic compounds into synthetically programable porous matrices, such as metal‐organic frameworks (MOFs), has come to the forefront as an emerging strategy for photochromic material development. This review highlights how the core principles of reticular chemistry (on the example of MOFs) play a critical role in the photochromic material performance, surpassing the limitations previously observed in solution or solid state. The symbiotic relationship between photoresponsive compounds and porous frameworks with a focus on how reticular synthesis creates avenues toward tailorable photoisomerization kinetics, directional energy and charge transfer, switchable gas sorption, and synergistic chromophore communication is discussed. This review not only focuses on the recent cutting‐edge advancements in photochromic material development, but also highlights novel, vital‐to‐pursue pathways for multifaceted functional materials in the realms of energy, technology, and biomedicine.
more »
« less
Breaking the photoswitch speed limit
Abstract The forthcoming generation of materials, including artificial muscles, recyclable and healable systems, photochromic heterogeneous catalysts, or tailorable supercapacitors, relies on the fundamental concept of rapid switching between two or more discrete forms in the solid state. Herein, we report a breakthrough in the “speed limit” of photochromic molecules on the example of sterically-demanding spiropyran derivatives through their integration within solvent-free confined space, allowing for engineering of the photoresponsive moiety environment and tailoring their photoisomerization rates. The presented conceptual approach realized through construction of the spiropyran environment results in ~1000 times switching enhancement even in the solid state compared to its behavior in solution, setting a record in the field of photochromic compounds. Moreover, integration of two distinct photochromic moieties in the same framework provided access to a dynamic range of rates as well as complementary switching in the material’s optical profile, uncovering a previously inaccessible pathway for interstate rapid photoisomerization.
more »
« less
- Award ID(s):
- 2103722
- PAR ID:
- 10474820
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Confinement‐imposed photophysics was probed for novel stimuli‐responsive hydrazone‐based compounds demonstrating a conceptual difference in their behavior within 2D versus 3D porous matrices for the first time. The challenges associated with photoswitch isomerization arising from host interactions with photochromic compounds in 2D scaffolds could be overcome in 3D materials. Solution‐like photoisomerization rate constants were realized for sterically demanding hydrazone derivatives in the solid state through their coordinative immobilization in 3D scaffolds. According to steady‐state and time‐resolved photophysical measurements and theoretical modeling, this approach provides access to hydrazone‐based materials with fast photoisomerization kinetics in the solid state. Fast isomerization of integrated hydrazone derivatives allows for probing and tailoring resonance energy transfer (ET) processes as a function of excitation wavelength, providing a novel pathway for ET modulation.more » « less
-
Abstract Cooperative behavior and orthogonal responses of two classes of coordinatively integrated photochromic molecules towards distinct external stimuli were demonstrated on the first example of a photo‐thermo‐responsive hierarchical platform. Synergetic and orthogonal responses to temperature and excitation wavelength are achieved by confining the stimuli‐responsive moieties within a metal–organic framework (MOF), leading to the preparation of a novel photo‐thermo‐responsive spiropyran‐diarylethene based material. Synergistic behavior of two photoswitches enables the study of stimuli‐responsive resonance energy transfer as well as control of the photoinduced charge transfer processes, milestones required to advance optoelectronics development. Spectroscopic studies in combination with theoretical modeling revealed a nonlinear effect on the material electronic structure arising from the coordinative integration of photoresponsive molecules with distinct photoisomerization mechanisms. Thus, the reported work covers multivariable facets of not only fundamental aspects of photoswitch cooperativity, but also provides a pathway to modulate photophysics and electronics of multidimensional functional materials exhibiting thermo‐photochromism.more » « less
-
Abstract Transition metal dichalcogenides (TMDCs) have received much attention for optoelectronic applications because of their band gap transition from indirect to direct as they decrease from multilayer to monolayer. Recent studies have experimented with the use of photochromic molecules to optically control the charge transport of two-dimensional (2D) TMDCs. In this work, a numerical study using density functional theory has been performed to test the possibility to control the optical property of 2D TMDC monolayers with various photochromic molecules. When the photochromic molecule’s highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO) energy levels are within the band gap of 2D TMDC monolayers, holes or electrons will transport to the photochromic molecules, resulting in the reduction of excitons in the 2D TMDC monolayers. The reduced optical response can be recovered by going through reverse isomerization of the photochromic molecules. Molybdenum disulfide (MoS2) and tungsten diselenide (WSe2) monolayers were tested with various photochromic molecules including azobenzene, spiropyran, and diarylethenes (DAE 2 ethyl, DAE 5 ethyl, DAE 5 methyl). The systematic study presented in this work displays that MoS2-Spiropyran and every diarylethene derivative used in this study except MoS2-DAE 5 methyl exhibited photo-switchable behavior.more » « less
-
The spatiotemporal regulation of chemical reactivity in biological systems permits a network of metabolic reactions to take place within the same cellular environment. The exquisite control of reactivity is often mediated by out-of-equilibrium structures that remain functional only as long as fuel is present to maintain the higher energy, active state. An important goal in supramolecular chemistry aims to develop functional, energy dissipating systems that approach the sophistication of biological machinery. The challenge is to create strategies that couple the energy consumption needed to promote a molecule to a higher energy, assembled state to a functional property such as catalytic activity. In this work, we demonstrated that the assembly of a spiropyran (SP) dipeptide (1) transiently promoted the proline-catalyzed aldol reaction in water when visible light was present as fuel. The transient catalytic activity emerged from 1 under light illumination due to the photoisomerization of the monomeric, O -protonated (1-MCH + ) merocyanine form to the spiropyran (1-SP) state, which rapidly assembled into nanosheets capable of catalyzing the aldol reaction in water. When the light source was removed, thermal isomerization to the more stable MCH + form caused the nanosheets to dissociate into a catalytically inactive, monomeric state. Under these conditions, the aldol reaction could be repeatedly activated and deactivated by switching the light source on and off.more » « less
