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© 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license. A.G. was supported by Myron Rosenblum Endowed Fellowship from Brandeis University., Photoswitching dynamics of common organic photoisomers in solid state are often reduced compared to the solution state due to the close packing of molecules that limits structural changes. The facile solid-state switching of photoisomers has implications in developing novel light-controlled devices such as actuator, field-effect transistor, and photodetector, as well as photon energy storage materials that can be charged by light and release thermal energy upon triggering. Thus, the solid-state photoswitching of organic molecules has been studied in relation to the structural characteristics, and various effective methods to enhance the switching in condensed phases have been developed. This review highlights isomerization dynamics of common photoswitches in solid and then introduces important strategies for facilitating the switching dynamics, including the covalent functionalization methods for small-molecule photoswitches as well as the incorporation of various templates such as porous medium, nanoparticle, and host-guest structure. Furthermore, the solid-state switching of molecules at the interface with inorganic substrates including 2D materials and the microscopy techniques for the characterization will be further described. (C) 2020 The Author(s). Published by Elsevier Ltd., Myron Rosenblum Endowed Fellowship from Brandeis University, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

It is well-known that the thermal isomerization kinetics of photochromic azo dyes can be modulated by subtle changes in their chemical architecture. However, the availability of an orthogonal input to control the thermal relaxation of azo dyes is essential to enable access to multifunctional and adaptive photochromic switches based on these particular organic chromophores. In this work, we have designed and synthesized a new family of green-light-activated heterocyclic azo derivatives that modify their switching capabilities as a function of concentration. In this line, we have investigated their self-assembly and the nature of the supramolecular aggregates formed by means of dynamic light scattering, polarized optical microscopy, and X-ray diffraction. Indeed, imparting control over the self-assembly of these organic dyes allows to fine-tune their thermal relaxation time and produce adaptable photochromic switches. Specifically, swapping the azo dye concentration between values located above and below the corresponding critical aggregation concentration modifies significantly the relaxation time up to 250 times, i.e., from the millisecond to the microsecond timescale. Moreover, the optical density of the system can be switched back and forth hundreds of times, for both diluted and concentrated solutions, without any sign of fatigue. © 2019 American Chemical Society.

Phenylazopyridines are photoisomerizable compounds with high potential to control biological functions with light. We have obtained a series of phenylazopyridines with light dependent activity as negative allosteric modulators (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5). Here we describe the factors needed to achieve an operational molecular photoisomerization and its effective translation into in vitro and in vivo receptor photoswitching, which includes zebrafish larva motility and the regulation of the antinociceptive effects in mice. The combination of light and some specific phenylazopyridine ligands displays atypical pharmacological profiles, including light-dependent receptor overactivation, which can be observed both in vitro and in vivo. Remarkably, the localized administration of light and a photoswitchable compound in the peripheral tissues of rodents or in the brain amygdalae results in an illumination-dependent analgesic effect. The results reveal a robust translation of the phenylazopyridine photoisomerization to a precise photoregulation of biological activity. © 2016 American Chemical Society.

Light-regulated drugs allow remotely photoswitching biological activity and enable plausible therapies based on small molecules. However, only freely diffusible photochromic ligands have been shown to work directly in endogenous receptors and methods for covalent attachment depend on genetic manipulation. Here we introduce a chemical strategy to covalently conjugate and photoswitch the activity of endogenous proteins and demonstrate its application to the kainate receptor channel GluK1. The approach is based on photoswitchable ligands containing a short-lived, highly reactive anchoring group that is targeted at the protein of interest by ligand affinity. These targeted covalent photoswitches (TCPs) constitute a new class of light-regulated drugs and act as prosthetic molecules that photocontrol the activity of GluK1-expressing neurons, and restore photoresponses in degenerated retina. The modularity of TCPs enables the application to different ligands and opens the way to new therapeutic opportunities.

© 2014, Springer-Verlag Berlin Heidelberg. Density functional theory (DFT) calculations have been used to investigate the structural properties, dipole moments, polarizabilities, Gibbs energies, hardness, electronegativity, HOMO/LUMO energies, and chemical potentials of trans and cis configurations of eight para-substituted azobenzene derivatives. All properties have been obtained using the B3LYP functional and 6-31++G(d,p) basis set. The planar structures have been obtained for all optimized trans configurations. The energy difference between trans and cis configurations for considered derivatives was found to be between 64.2–73.1 kJ/mole. It has been obtained that the p-aminodiazo-benzene (ADAB) has the difference in the dipole moments between trans and cis forms higher than for trans and cis azobenzene.

© 2014, Springer-Verlag Berlin Heidelberg. Density functional theory (DFT) calculations have been used to investigate the structural properties, dipole moments, polarizabilities, Gibbs energies, hardness, electronegativity, HOMO/LUMO energies, and chemical potentials of trans and cis configurations of eight para-substituted azobenzene derivatives. All properties have been obtained using the B3LYP functional and 6-31++G(d,p) basis set. The planar structures have been obtained for all optimized trans configurations. The energy difference between trans and cis configurations for considered derivatives was found to be between 64.2–73.1 kJ/mole. It has been obtained that the p-aminodiazo-benzene (ADAB) has the difference in the dipole moments between trans and cis forms higher than for trans and cis azobenzene.