Photoswitchable Boronic Acid Derived Salicylidenehydrazone Enabled by Photochromic Spirooxazine and Fulgide Moieties: Multiple Responses of Optical Absorption, Fluorescence Emission, and Quadratic Nonlinear Optics

Abstract

A novel protocol of the boronic acid derived salicylidenehydrazone (BASHY) core being sandwiched by photochromic spirooxazine and fulgide moieties was proposed here to design multistate fluorescent photoswitches with variable nonlinear optical (NLO) responses. Systematic investigations of their optical absorption, fluorescence emission, and static first hyperpolarizabilities (β) were performed using density functional theory (DFT). It was found that the BASHY-based sandwiched series exhibited significant differences of absorption and emission properties among three photoisomers, which were essentially ascribed to the massive changes of corresponding electron transition characteristics quantified by hole–electron descriptors and visualized by electron density difference (EDD) plots. However, the isomerization of fulgide parts in the merocyanine (MC) form of spirooxazine failed to greatly shift maximum absorption/emission wavelengths, due to their high similarity of intrinsic transition features. Furthermore, large β contrasts between three photoisomers were observed, which resulted from significant variations of contributions of spirooxazine and/or fulgide moieties to the total β upon photoisomerization according to β densities. Although the fulgide moiety contributes negatively and positively to spirooxazine (SO) isomers when fulgide switches from close (C-) to open (E-) forms, respectively, their dominant β xxx values with opposite signs are still similar in magnitude, leading to quite close quadratic NLO responses. Therefore, the captivating ternary photoswitches with multiple responses of absorption, emission, and NLO were elaborately built in this context, promising to be applied as multifunctional optical materials in various scientific and technological fields.

Facile development of photochromic cellulose acetate transparent nanocomposite film immobilized with lanthanide‐doped pigment: ultraviolet blocking, superhydrophobic, and antimicrobial activity

“…[ 62 ] However, organic colourants have demonstrated a number of drawbacks, such as photo‐degradation, constraints due to the resulting film hardness, inhibition of photochromism, and poor fastness to light. [ 63 ] Some of those disadvantages have been resolved using microencapsulation processes to increase the stability of the photoswitchable chromophore. [ 64 ] However, this generally results in harshness and stiffness in the film matrix, which reduces the film comfort to the consumer.…”

A Thorough Theoretical Exploration of Intriguing Characteristics of Cyclo[18]carbon: Geometry, Bonding Nature, Aromaticity, Weak Interaction, Reactivity, Excited States, Vibrations, Molecular Dynamics and Various Molecular Properties

“…The hole-electron analysis developed by us is a very useful and powerful method in unraveling nature of electron excitations [89] and has been employed by quite a few research articles. [90][91][92] In many cases, the electronic excitation cannot be well represented by only one pair of MO transition, bringing great difficulty in examining its characteristics. This difficulty is completely resolved in our hole-electron analysis.…”

Fulgide Derivative-Based Solid-State Reversible Fluorescent Switches for Advanced Optical Memory

“…FUL and its derivatives exhibit visual changes in color and fluorescence in solution under alternating irradiation by UV and visible light. [40][41][42] Also, they often exhibit good thermal stability, easy synthesis, high fatigue resistance, and reliable photoswitch reactivity in both solution and solid state, which are regarded as efficient fluorescent switches and promising molecules for applications in optical memory devices. [43][44][45] However, to the best of our knowledge, there have been no reports of solid-state fluorescent switches based on FUL and its derivatives due to the aggregation-induced quenching (ACQ) effect caused by the planar structure of the FUL moiety, resulting in weak or no fluorescence in the solid state.…”