Photoactive Fluorinated Poly(azomethine)s with Azo Groups in the Main Chain for Optical Storage Applications and Controlling Liquid Crystal Orientation

Abstract

Polymer multicomponent materials containing conjugated fragments (such as azo- or azomethine groups) have attracted significant attention due to their possible use in the efficient reversible stimuli-responsive, light-responsive devices. Light-responsive polyazomethines with azo groups in the backbone (Azo-Pams) are synthesized by polycondensation of tetrafluoro­benzene- or octafluoro­biphenylene-based bis-hydroxy­benzaldehydes with hexamethylene­diamine. The polymers feature the simultaneous combination of azo and azomethine groups inside one conjugated block. The synthesized polymers can be solution cast into flexible solid films with tensile strength of about 24 MPa. We found that the obtained Azo-Pam polymers have an amorphous structure (T g ∼ 134 °C) and high thermal stability (up to 300 °C). Their optical spectra depend on the solvent type and its pH which influence the dynamical equilibrium between the tautomeric forms. It also determines the balance between the main (azo form) and the ionized form in the solvent and allows to purposefully regulate the absorption maxima. We demonstrate the ability to record optical information using Azo-Pam films in the form of polarization gratings (holograms) with a regulated diffraction efficiency. A uniform orientation of liquid crystal is achieved by a polarized UV irradiation of glass substrates covered with the polymer Azo-Pam-II. The obtained data show that the synthesis strategy of the Azo-Pam polymers is an effective instrument for designing a wide range of stimuli-responsive and optical active materials.

Crystal structure and Hirshfeld surface analysis of 1-[(E)-2-(5-chloro-2-hydroxyphenyl)hydrazin-1-ylidene]naphthalen-2(1H)-one

“…Apart from their use as colourants, azo compounds have attracted a lot of attention from chemists as their potential applications are important in coordination chemistry (Asha & Mandal, 2018), metal-organic frameworks (MOFs) (Huang et al, 2017), covalent-organic frameworks (COFs) (Chandra et al, 2014) and catalysis (Choudhary et al, 2017). In addition, they have found many applications in different fields such as non-linear optics (Dudek et al, 2020), optical storage (Kovalchuk et al, 2020), photoluminescence (He et al, 2019), chemosensors (Akram et al, 2020) and magnetism (Nandi et al, 2021). They are used not only in physics but also in the biomedical and pharmacological fields as they can offer new therapeutic properties such as antiviral (Chhetri et al, 2021), antimicrobial (Kyei et al, 2020), anti-inflammatory and antioxidant (Unnisa et al, 2020).…”

To Isomerize or not to Isomerize? E/Z Isomers of Cyclic Azobenzene Derivatives and Their Reactivity Upon One‐Electron Reduction

“…Accordingly, molecules comprising an azo moiety display unique properties depending on the prevailing isomer. This is for example, illustrated using azo moieties in self‐healing polymers, [1–4] where switching between E and Z leads to an intrinsically differing topology causing remarkable macroscopic effects (softness/hardness of the material). The higher bulkiness of substituted Z isomers vs. the E is the basic principle in photopharmacology [2,5–8] .…”

Well‐ordered nanostructured organic/inorganic hybrid thin film construction via UV nanoimprint lithography applicable to liquid crystal systems

“…The LCs also have elastic and collective characteristics because of their intermediate state between a liquid and solid 7 . Because of these unique characteristics, the LC has a high potential to be applied in many fields such as optics, 8 electronics, 9 and chemistry 10,11 . Uniform alignment of LC molecules is one of the most important technologies for advanced LC device applications for its uniform light controllability.…”

“…7 Because of these unique characteristics, the LC has a high potential to be applied in many fields such as optics, 8 electronics, 9 and chemistry. 10,11 Uniform alignment of LC molecules is one of the most important technologies for advanced LC device applications for its uniform light controllability. The physiochemical interaction (such as dipole-dipole interaction, 12 geometric restriction, 13 etc.)…”