- A luminescence molecular switch via modulation of PET and ICT processes in DCM system
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A novel versatile dicyanomethylene-4H-pyran (DCM) based derivative bearing ferrocenyl group (DCM-N-Fc) is designed as modulator to construct “off-on” logic operation. The optical properties of DCM-N-Fc are characterized by absorption and steady-state fluorescence technique, showing that the fluorescence from DCM chromophore via intramolecular charge transfer (ICT) is strongly quenched by photoinduced electron transfer (PET) process from ferrocene moiety. In contrast with the references (DCM-N and DCM-Fc), the fluorescence of DCM-N-Fc can be triggered by oxidizing ferrocenyl unit either chemically or electrochemically, exhibiting a characteristic emission modulation at around 610 nm with an electrofluorochromic behavior. Furthermore, the free energy and the fluorescence lifetime in the PET path verify the thermodynamic feasibility. Cyclic voltammetry, absorption spectroscopy, time-resolved fluorescence as well as DFT calculation have been used to elaborate the manipulation via both PET and ICT processes.
- Yang, Jinfeng,Li, Meng,Kang, Lihua,Zhu, Weihong
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- Transition metal-catalyzed C–N cross-coupling reaction of bromine-substituted pyranilidene derivatives: synthesis, characterization, and optical properties study of pyran-based chromophores
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Abstract: In this work, the C–N cross-coupling reaction between bromine-substituted pyranilidene derivatives, and a variety of secondary amines was studied in the presence of transition metal catalysts. The CuI/l-proline, Pd(OAC)2/PPh3, and MnCl2.6H2O/l-proline were chosen as catalyst/ligand systems. The copper-catalyzed Ullmann amination reaction in the presence of l-proline as auxiliary ligand shows the best yield. The structure of pyran-based chromophores was confirmed using FT-IR, 1H NMR, 13C NMR, and mass spectroscopy. Additionally, the linear optical properties of final compounds were investigated using UV–Vis and fluorescent spectroscopy. The large stokes shifts for final compounds show the capability of using these compounds in optical applications. Graphic abstract: [Figure not available: see fulltext.].
- Rahimpour, Keshvar,Zarenezhad, Hassan,Teimuri-Mofrad, Reza
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- A fluorescent compound and its use on medicine
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The invention relates to a fluorescent compound with A beta plaque affinity and a composition which contains the derivative, namely the fluorescent compound. The fluorescent compound is as shown in a general formula (I), wherein a substituent group in the general formula (I) is as shown in the specification. The invention also relates to a preparation method of the fluorescent compound and an application of the fluorescent compound in a method for developing A beta plaques.
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Paragraph 0057-0058
(2017/08/25)
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- Ion-Responsive Fluorescent Compounds, 2. Cation-Steered Intramolecular Charge Transfer in a Crowned Merocyanine
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The dimethylamine group of DCM (4-dicyanomethylene-2-methyl-6--4H-pyran), a well-known merocyanine often used as a laser dye, has been replaced by a macrocycle (monoaza-15-crown-5) which acts also as an electron donating substituent.The resulting fluoroionophore (DCM-crown) has almost identical photophysical properties as DCM, but upon complexation by alkaline-earth-metal-cations, it undergoes drastic changes in absorption spectrum (hypsochromic shift and hypochromic effect) and fluorescence quantum yield (quenching), whereas the emission spectrum is only slightly blue-shifted and the fluorescence lifetime is almost unchanged.These effects which strongly depend on the charge density of the cation can be interpreted in terms of cation-steered reduction of the efficiency of tranfer from a nonemissive locally excited state to an emissive relaxed intramolecular charge-transfer state (RICT).
- Bourson, Jean,Valeur, Bernard
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p. 3871 - 3876
(2007/10/02)
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