Photochromic Thienylpyridine–Bis(alkynyl)borane Complexes: Toward Readily Tunable Fluorescence Dyes and Photoswitchable Materials

Photoisomerization-switchable second-order nonlinear optical responses of dithienylethene-containing boron derivatives: a theoretical study

The switchable second-order nonlinear optical properties of a series of dithienylethene-containing boron compounds possessing reversible photochromic behavior have been systemically investigated based on density functional theory. The significant differences on the static first hyperpolarizabilities caused by the photoisomerization reaction confirm the switchable nonlinear optical behavior. Results show that the closed-ring 1c–4c possess large static first hyperpolarizabilitieswith respect to their corresponding open-ring 1o–4o, which is due to the better π-conjugation and a more obvious degree of charge transfer. Specifically, the static first hyperpolarizability values increase in the range of 2.4–5.2 times with the strengthening electron-withdrawing ability of the substituent R (R = H, CF3, NO2) on the pyridine and elongating the conjugated chains. It indicates that introducing boron-based functional groups to the dithienylethene monomer and modifying the pyridine ring can effectively improve the switching nonlinear optical responses.

Photoswitching of triplet–triplet annihilation upconversion showing large emission shifts using a photochromic fluorescent dithienylethene-Bodipy triad as a triplet acceptor/emitter

A dithienylethene-Bodipy triad was used as a photoswitchable triplet acceptor/emitter for photoswitching of triplet–triplet annihilation upconversion with large emission wavelength changes.

Aggregation-Induced Emission Rotors: Rational Design and Tunable Stimuli Response

A novel molecular design strategy is provided to rationally tune the stimuli response of luminescent materials with aggregation-induced emission (AIE) characteristics. A series of new AIE-active molecules (AIE rotors) are prepared by covalently linking different numbers of tetraphenylethene moieties together. Upon gradually increasing the number of rotatable phenyl rings, the sensitivity of the response of the AIE rotors to viscosity and temperature is significantly enhanced. Although the molecular size is further enlarged, the performance is only slightly improved due to slightly increased effective rotors, but with largely increased rotational barriers. Such molecular engineering and experimental results offer more in-depth insight into the AIE mechanism, namely, restriction of intramolecular rotations. Notably, through this rational design, the AIE rotor with the largest molecular size turns out to be the most viscosensitive luminogen with a viscosity factor of up to 0.98.

Structural modification strategies for the rational design of red/NIR region BODIPYs

The structure–property relationships of red/NIR region BODIPY dyes is analyzed, so that trends in their photophysical properties can be readily compared.

Synthesis, photochromic, and computational studies of dithienylethene-containing β-diketonate derivatives and their near-infrared photochromic behavior upon coordination of a boron(III) center

A series of dithienylethene-containing 1-thienyl-3-aryl-propane-1,3-diones (aryl = phenyl (Ph), thienyl (Th), and 4,5-bis(2,5-dimethylthiophen-3-yl)thiophen-2-yl (DTE-Th)) and the corresponding boron(III) diketonates, (O^O)BR(2) (R = F, C(6)F(5), and Ph), have been designed and synthesized. Their photophysical, electrochemical, and photochromic properties have been studied. Upon coordination of a boron(III) center, the closed forms of the dithienylethene-containing β-diketonates show near-infrared response and the photochromic behavior was also found to be affected by the aryl substituents at the 3-position of the β-diketonates. Moreover, computational studies have been performed that help to provide an understanding of the effect of substituents on the photophysical and photochromic properties.