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Water-sensitive ratiometric fluorescent probes and application to test strip for rapid and reversible detection of water
摘要： Naphthalimide-decorated fluorinated acetamides 1 and 2 were developed as solvent-sensitive dual emissive fluorescence probes. Particularly, 1 exhibited dual emission with a large Stokes shift for water, DMF, and DMSO solvents over other various organic solvents. The dual emission might be due to the increase of intramolecular charge transfer (ICT) of the naphthalimide moiety through the association of the difluorinated acetamide group with the solvent molecules. The 1 can give rise to a ratiometric change in the dual emission and a visual fluorescent color change depending on the water contents in organic solvents, including ethanol, methanol, acetonitrile and DMF solvents. Moreover, the 1-impregnated paper strips showed a rapid and easy-to-visualize fluorescent color change enabling water detection in organic solvents. These simple-to-use paper strips were also found to be reusable over 20 times.
关键词： Naphthalimide,Ratiometric fluorescence probe,Reusable test strip,Intramolecular charge transfer (ICT),Water detection
更新于2025-11-19 16:46:39
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Synthesis, characterization and photophysical properties of a new class of pyrene substituted 1,3,4-oxadiazole derivatives
摘要： We have designed and synthesized a series of a new class of pyrene substituted 1,3,4- oxadiazole derivatives (abbreviated as 3(a-e)) through palladium catalyzed Suzuki-Miyaura cross coupling reaction. The chemical structures of the probes were characterized by using analytical techniques namely 1H NMR, 13C NMR, FT-IR and GC-MS. The novel bipolar molecules consist of pyrene as an electron donor unit (D) and electron-deficient 1,3,4-oxadiazole as an acceptor unit (A) linked via extending π conjugation through a phenyl spacer with para linkages (D-π-A). Intramolecular charge transfer is improved by structure-property relationship. The detailed photophysical/solvatochromic properties of newly synthesized derivatives have been studied employing steady state spectroscopic techniques. The photophysical studies revealed that compounds emit strong indigo-blue fluorescence and efficient blue emission extending into blue-green in solid phase with high quantum yields. Thermal and morphological stabilities of the derivatives were studied employing DSC and TGA measurements. In addition, density functional theory (DFT) computations have been carried out to demonstrate various intramolecular interactions that cause the stabilization of the compound leading to its optoelectronic applications. The highest occupied molecular orbital energy (HOMOs), lowest unoccupied molecular orbital energy (LUMOs), the energy bandgap, chemical hardness (η), softness (δ), electronegativity (χ) and chemical potential (μ) were computed with the help of frontier molecular orbitals. The results were compared and discussed with the experimental results. The results demonstrate that the novel pyrene containing oxadiazole derivatives could be used as small organic molecules for multifunctional organic light-emitting devices (OLED)/optoelectronic devices.
关键词： Intramolecular charge transfer (ICT),1,3,4-Oxadiazole,Quantum yield,Pyrene,Density functional theory
更新于2025-09-23 15:23:52
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D‐A Type Pendant Conjugated Molecules based on Triazine Center with Depressed Intramolecular Charge Transfer Characteristics as Gain Media for Organic Semiconductor Lasers
摘要： A set of fluorene-capped pendant conjugated molecules (T-m and T-p), which consist of triazine center with three carbazole substituents as the donor-acceptor (D-A) type pendant structure, were designed, synthesized and investigated as gain media for organic semiconductor lasers (OSLs). Particularly, varying the capping positions of the fluorene units onto the pendant core structures results in obviously different intramolecular charge transfer (ICT) properties, whereas T-m manifested depressed ICT characteristic and high fluorescence quantum yield. The lowest ASE threshold in neat films was recorded of 1.9 μJ/cm2 for T-m and 83.8 μJ/cm2 for T-p, respectively, which indicated that depressed ICT characteristic in the case of T-m helps to enhance the ASE properties. Remarkably, the ASE threshold remained almost unchanged and the ASE spectra showed very small shifts (within 1 nm) for T-m with film samples annealed up to 180°C in open air. In contrast, its linear counterpart 2FEtCz-m showed obviously increased ASE threshold upon annealing above 100°C. The results suggest that the selective construction of conjugated pendant molecules with depressed ICT characteristics is beneficial for finely modulating the optical and electrical properties as well as improving the thermostability and photostability, which manifests the great potentials as robust gain media for OSLs.
关键词： Organic semiconductors,Amplified spontaneous emission (ASE),Organic semiconductor lasers,Pendant conjugated molecules,Intramolecular charge transfer (ICT)
更新于2025-09-12 10:27:22
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A solid-state emissive and solvatofluorochromic fluorophore and its application in high-contrast, fast, and repeatable thermochromic blends
摘要： Organic thermochromic luminescent materials are very promising in applications of thermo-history recording, sensing and anti-counterfeiting. However, the current reported organic thermochromic systems still have the drawbacks of slow responsive speed, low colour contrast and unsatisfactory repeatability. In this paper, we reported a twisted fluorophore based on 1,4-bis[2,2-bisphenyl-vinyl]benzene skeleton with A-D-A structure (OD-CN), which shows strong solvatochromism in solution with emission shifts up to 135 nm, highly efficient red emission in solid state (660 nm, 11.62%) and unprecedented thermochromic behaviour in linear low density polyethylene matrix with high emission contrast (red to greenish yellow), fast responsiveness (within 1 s) and good repeatability (over 10 times). OD-CN doped LLDPE films show potential applications in anti-counterfeiting and as an example, it was applied as multi-channel anti-counterfeiting printings on paper money. What's more, the strategy of blending fluorophores with solvent effects and solid-state emission into apolar polymer matrixes to realize thermochromisms is general.
关键词： Thermochromism,Intramolecular charge transfer (ICT),Aggregation induced emission enhancement (AIEE),1,4-bis[2,2-bisphenyl-vinyl]benzenes
更新于2025-09-04 15:30:14