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Alkyl chains length dependent fluorescence emission and reversible mechanofluorochromism of AIEE-based quinoline derivatives
摘要： Five quinoline derivatives containing different alkyl chains (QLACn, n ? 2, 4, 6, 8, 12) were synthesized to investigate the effect of alkyl chains on their photophysical properties. The ?uorescent properties of the QLACn were affected by the alkyl chains, which indicated obvious blue-shifting trend and ?uorescence emission are alkyl chains length-dependent by grinding-induced spectral shifts (DlMFC). Longer alkyl-length revealed larger DlMFC. Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements indicated that the transformation between microcrystalline and amorphous states upon external stimuli should be responsible for the observed reversible MFC behavior.
关键词： Alkyl chains length-dependent behavior,Quinoline derivatives,Aggregation-induced emission enhancement (AIEE) behavior,Mechano?uorochromism behavior
更新于2025-09-23 15:23:52
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Optically Tunable Field Effect Transistors with Conjugated Polymer Entailing Azobenzene Groups in the Side Chains
摘要： Semiconducting conjugated polymers with photoswitching behavior are highly demanded for field-effect transistors (FETs) with tunable electronic properties. Herein a new design strategy is established for photoresponsive conjugated polymers by incorporating photochromic units (azobenzene) into the flexible side alkyl chains. It is shown that azobenzene groups in the side chains of the DPP (diketopyrrolopyrrole)-quaterthiophene polymer (PDAZO) can undergo trans/cis photoisomerization in fully reversible and fast manner. Optically tunable FETs with bistable states are successfully fabricated with thin films of PDAZO. The drain-source currents are reduced by 80.1% after UV light irradiation for ≈28 s, which are easily restored after further visible light irradiation for ≈33 s. Such fast optically tunable FETs are not reported before. Moreover, such current photomodulation can be implemented for multiple light irradiation cycles with good photofatigue resistance. Additionally, thin film charge mobility of PDAZO can be reversibly modulated by alternating UV and visible light irradiations. On the basis of theoretical calculations and GIWAXS data, it is hypothesized that the dipole moment and configuration changes associated with the trans-/cis-photoisomerization of azobenzene groups in PDAZO can affect the respective intra-chain and inter-chain charge transporting, which is responsible for the optically tunable behavior for FETs with thin films of PDAZO.
关键词： side alkyl chains,semiconducting polymers,thin-film field-effect transistors,azobenzene,photoresponsiveness
更新于2025-09-19 17:15:36
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Alkyl chain-dependent cyano-stilbene derivative's molecular stacking, emission enhancement and fluorescent response to the mechanical force and thermal stimulus
摘要： Two cyano-stilbene derivatives with butyl (C4MPA) and octyl groups (C8MPA) were synthesized to investigate the effects of alkyl chains on molecular stacking, emission enhancement, and mechanofluorochromism. The two compounds displayed weak emissions in monomolecular state and emitted an enhanced fluorescence in crystal state. However, the fluorescence quantum yield of C4MPA (19%) was lower than that of C8MPA (76%). Face-to-face dimer stacking was found only in the C4MPA crystal, in which molecules adopted a nonplanar configuration. The C8MPA crystal presented two kinds of antiparallel 1D arrangement. One involved the antiparallel stacking of nonplanar aromatic moieties. The other consisted of coplanar molecules without π-π stacking, which were responsible for the higher luminescence yield. Moreover, the emission of the C4MPA solid was quenched under mechanical force, whereas the C8MPA solid still emitted a strong fluorescence after grinding. C8MPA lost fluorescence when heated at above 60 °C because of its low melting point, and the supercooling viscous liquid without fluorescence was observed even the sample was cooled to room temperature for 10 h, meaning a very slowly crystallization process. Such non-emissive supercooling viscous liquid might rapidly transform into strongly emissive solid under the mechanical force shearing stimulus. Thus, C8MPA films could be used as sensors for mechanical force and thermal stimuli.
关键词： mechanofluorochromism,emission enhancement,molecular stacking,thermal stimulus,cyano-stilbene derivatives,alkyl chains
更新于2025-09-04 15:30:14