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Precise manipulation of Bragg reflection in cholesteric liquid crystals (CLCs) is essential for advancing reconfigurable optics. However, existing photo-responsive material-doped CLC technologies that rely on single-wavelength photoisomerization encounter several challenges, including slow response times, limited tunability, inadequate spatial control, and instability caused by pitch variations due to diffusion. Here, we present a robust dual-wavelength photoisomerization method to simultaneously achieve -to- and -to- photoisomerization of chiral azobenzene-doped CLCs, which enables broadband, reversible, and spatially addressable control over the Bragg reflection spectrum. By employing counterpropagating laser beams at 405 nm and 532 nm, we precisely control the isomerization dynamics of azobenzene chiral dopants, achieving spectral shifts exceeding 100 nm primarily through reversible modulation of the helical pitch of the CLCs. Furthermore, manipulating the intensity ratio and geometry of the excitation beams allows for tailored pitch gradients, reflection bandwidths, and central wavelengths with remarkable fidelity. Our approach enhances pitch boundaries and reduces molecular diffusion, facilitating the micrometer-scale patterning of optical textures, which surpasses traditional single-wavelength methods. Additionally, we present an innovative narrowband spectral filtering technique by sequentially transmitting light through pitch-selective CLC regions under circular polarization control. This reconfigurable manipulation strategy paves the way for developing programmable photonic systems, including adaptive optics, diffractive optics, and tunable displays.

Photo‐switchable coatings for lithium ion batteries (LIB) can offer the possibility to control the diffusion processes from the electrode materials to the electrolyte and thus, for example, reducing the energy loss in the fully charged state. Fulgide derivatives, as known photo‐switches, are investigated concerning their use as coating for vanadium pentoxide, a potential cathode material for LIB. With the help of Density Functional Theory calculations, two fulgide derivatives are characterized with respect to their photophysics, their aggregation behaviour on the cathode material and the ability to form self‐assembled monolayers (SAM). Furthermore, the two states of the photo‐switchable coating are tested with respect to lithium diffusion from the cathode material, passing the SAM and entering the electrolyte. We found a difference for the energy barriers depending on the state of the photo‐switch, preferring its closed form. This behaviour can be used to prevent the loss of charge in batteries of portable devices. Photo‐switchable coatings for electrodes of lithium‐ion batteries offer a potential method for externally controlling diffusion processes. Fulgide derivatives, in the form of self‐assembled monolayers on vanadium pentoxide, are studied using density functional theory simulations to investigate the influence of the state of the photo‐switch on the diffusion barriers of lithium ions, revealing a significant difference.

Light can be used to regulate protein interactions with a high degree of spatial and temporal precision. Photo-switchable systems therefore allow the development of controllable protein complexes that can influence various cellular and molecular processes. Here, we describe a plant virus-based nanoparticle shuttle for the distribution of proteins that can be released when exposed to light. Potato virus X (PVX) is often used as a presentation system for heterologous proteins and epitopes, and has ideal properties for biomedical applications such as good tissue penetration and the ability to form hydrogels that present signaling molecules and promote cell adhesion. In this study, we describe three different systems attached to the surface of PVX particles: LOVTRAP, BphP1/QPAS1 and Dronpa145N. We demonstrated the functionality of all three photo-switchable protein complexes in vitro and the successful loading and unloading of PVX particles. The new systems provide the basis for promising applications in the biomedical and biomaterial sciences.

α,ω‐Bis(1,8‐dichloroanthracen‐10‐yl)alkanes with (CH2)n‐linker units (n=1–4) were synthesized starting from 1,8‐dichloroanthracen‐10(9H)‐one. This was transformed into anthracenes with allyl, bromomethyl and propargyl substituents in position 10; these were converted in various C−C‐bond formation reactions (plus hydrogenation), leading to two anthracene units flexibly linked by α,ω‐alkandiyl groups. 1,2‐Ethandiyl‐ and 1,3‐propandiyl‐linked derivatives were functionalized with ethynyl groups in positions 1, 8, 1’ and 8’, and these terminally functionalized by Me3Sn groups using Me2NSnMe3. All linked bisanthracenes were subjected to UV light induced cyclomerization and a series of 9,10 : 9’,10’‐photo‐cyclomers were obtained. Their thermal cycloreversion and (repeated) switchability was demonstrated. 1,3‐Bis1,8‐bis[(trimethylstannyl)ethynyl]anthracen‐10‐ylpropane served as model compound for photo‐switchable acceptor molecules and its open and closed forms were characterized by NMR and DOSY experiments. Light on the switch: Linked bisanthracenes bearing four (partly metal‐containing) substituents undergo photo‐cyclomerization that enables the parallelization of all four functions and can be thermally reopened by cycloreversion which allows repeated switchability.

This chapter provides an introduction to the background and significance of photonic sensitive materials from inorganic, organic, and biological sources. It describes the changes under photoirradiation and the classification of photonic sensitive materials. It then reviews the application of these materials in different areas such as photoswitchable wettability of surfaces, optical switches in channels, optobioelectronic devices, and biomedical uses.

Collagen is a vital component of the extracellular matrix in animals. Collagen forms a characteristic triple helical structure and plays a key role in supporting connective tissues and cell adhesion. The ability to control the collagen triple helix structure is useful for medical and conformational studies because the physicochemical properties of the collagen rely on its conformation. Although some photo-controllable collagen model peptides (CMPs) have been reported, satisfactory photo-control has not yet been achieved. To achieve this objective, detailed investigation of the isomerization behavior of the azobenzene moiety in CMPs is required. Herein, two CMPs were attached via an azobenzene linker to control collagen triple helix formation by light irradiation. Azo-(PPG)10 with two (Pro-Pro-Gly)10 CMPs linked via a photo-responsive azobenzene moiety was designed and synthesized. Conformational changes were evaluated by circular dichroism and the cis-to-trans isomerization rate calculated from the absorption of the azobenzene moiety indicated that the collagen triple helix structure was partially disrupted by isomerization of the internal azobenzene.

The turn-off fluorescent photoswitches for information encryption are constantly being developed. However, there are no reports about time-switchable (fluorescence lifetime-switchable) encryption to overcome the limitations of tunable encoding numbers in spectrally and temporally encoded libraries. Based on the double-exponential fitting of fluorescence lifetime, we propose, a fatigue-free and highly flexible switch between the amplitude-weighted average fluorescence lifetime ( ) and the intensity-weighted average fluorescence lifetime ( ), which will realize the supermultiplexed fluorescence lifetime switchable encryption. The potentially enormous library of different fluorescent lifetime combinations would facilitate the development of information security.

Newly designed and synthesized diarylethene (DAE) derivatives with aliphatic amine sidearms and one with two pyrenes, revealed excellent photo-switching property of central DAE core in MeOH and water. The only exception was bis-pyrene analogue, its DAE core very readily photochemically closed, but reversible opening completely hampered by aromatic stacking interaction of pyrene(s) with cyclic DAE. In this process, pyrene fluorescence showed to be a reliable monitoring method, an open form characterized by strong emission at 480 nm (typical for pyrene-aggregate), while closed form emitted weakly at 400 nm (typical for pyrene-DAE quenching). Only open DAE-bis-pyrene form interacted measurably with ds-DNA/RNA by flexible insertion in polynucleotide grooves, while self-stacked closed form did not bind to DNA/RNA. For the same steric reasons, flexible open DAE-bis-pyrene form was bound to at least three different binding sites at bovine serum albumin (BSA), while rigid, self-stacked closed form interacted dominantly with only one BSA site. Preliminary screening of antiproliferative activity against human lung carcinoma cell line A549 revealed that all DAE-derivatives are non-toxic. However, bis-pyrene analogue efficiently entered cells and located in the cytoplasm, whereby irradiation by light (315–400 nm) resulted in a strong, photo-induced cytotoxic effect, typical for pyrene-related singlet oxygen species production.

A series of stiff stilbene macrocycles have been studied to investigate the possible impact of the macrocycle ring size on their photodynamic properties. The results show that reducing the ring size counteracts the photoisomerization ability of the macrocycles. However, even the smallest macrocycle studied (stiff stilbene subunits linked by a six carbon chain) showed some degree of isomerization when irradiated. DFT calculations of the energy differences between the E - and Z -isomers show the same trend as the experimental results. Interestingly the DFT study highlights that the energy difference between the E - and Z -isomers of even the largest macrocycle (linked by a twelve carbon chain) is significantly higher than that of the stiff stilbene unit itself. In general, it is indicated that addition of even a flexible chain to the stiff stilbene unit may significantly affect its photochemical properties and increase the photostability of the resulting macrocycle.