White Light Induced E/Z-Photoisomerization of Diphenylamine-Tethered Fluorescent Stilbene Derivatives: Synthesis, Photophysical, and Electrochemical Investigation

Abstract

A facile synthesis and detailed photophysical investigation of E/Z-isomerization of fluorescent diphenylamine tethered stilbene derivatives (DPASs) under white light exposure have been carried out to understand the effect on fluorescence, electrochemical properties, and photostability under various activation/deactivation pathways. In solution state, in the dark, the E-isomer of DPASs (6a-d) exhibited high fluorescence quantum yields (Φ ≈ 53% to 60% in DMSO). However, on white light exposure, H NMR and HPLC studies revealed that pure E-isomer of the DPAS 6a (∼9.5 mM) started converting into its Z-form by photoisomerization until it reaches to nearly equilibrium. At low concentrations (∼10 μM), the absorption band of the pure E-isomer in the range of 350-450 nm gradually decreased to adopt Z-conformation 6a' until a photostationary state was reached. The structure of the E-isomer 6a was unequivocally confirmed by X-ray diffraction analysis. The synthesized DPAS compounds 6a-d possessed positive solvatochromic properties, two photon absorption properties, and good thermal stability. The electrochemical investigations using DPASs showed reversible oxidation resulting in formation of a stable radical cation. Owing to useful photophysical, electrochemical and thermal properties, these DPAS derivatives are suitable for their application in biomedical imaging as well as in fabrication of electroluminescent materials.

“Seeing” and Controlling Photoisomerization by (Z)-/(E)-Isomers with Aggregation-Induced Emission Characteristics

“…In unnatural systems, photoisomerization of olefinic chromophores has been used in molecular probes, molecular machines, − and light-triggered photoswitches. − A photochemical reaction that switches a molecule from one isomer to the other with different geometry and property in a high η iso will continue to play a vital role in synthetic chemistry and material science. However, many ( Z )- and ( E )-isomers with a carbon–carbon double bond usually reach the dynamic equilibrium with non-100% conversion or almost equal concentration due to their similar bond energy, − which makes the desired large change of function and geometry upon ( Z )- or ( E )-photoisomerization to be compromised. Thus, the development of a facile approach to promote a unidirectional photoisomerization of olefins is fundamentally significant.…”

Synthesis of some new distyrylbenzene derivatives using immobilized Pd on an NHC-functionalized MIL-101(Cr) catalyst: photophysical property evaluation, DFT and TD-DFT calculations

“…It should be noted that the more solvent dependency of emission spectra compared to that of absorption spectra for all compounds could be attributed to more ICT characteristic of the samples in their excited state than that of their ground states. [69][70][71] The pH sensitivity of D-p-A DSBs were also evaluated and results are summarized in Table 4. As detailed in this table, upon decreasing the pH from 7 to 3, no meaningful change was observed in emission band of the samples.…”

“…Stilbene compounds are a signicant class of uorescent organic p-conjugated compounds, which are widely used in the above mentioned applications. [17][18][19][20][21][22][23][24][25][26] Due to the systematic relationship between the uorescence properties of the uorescent materials and their chemical structures, stilbenes are an interesting class of compounds which permit us to simply ne tune the photophysical properties via available chemical modications. [27][28][29][30][31] To synthesize stilbenes, different organic methodologies such as Wittig reaction, [32][33][34] Horner-Wadsworth-Emmons reaction, 35 catalytic aldehyde olenations, 36 and Mizoroki-Heck reaction 37,38 have been developed.…”

Photo‐Responsive Fluorescent Materials with Aggregation‐Induced Emission Characteristics

“…[93] Currently, photo-induced E/Z isomerization has been applied in various fields. [94,95] Introducing E/Z isomerism into an AIEgen can change the steric hindrance and further affect its luminescent properties. [96,97] By virtue of the advantages of easy operation and convenient regulation, photoinduced E/Z isomerization offers a unique avenue into research on the characteristics and connections of these materials, which is important for exploring practical applications.…”