Synthesis, Properties And Theoretical Calculation Of Organic Luminescent Materials Based On Pyrenes And BODIPY

In recent years, organic optical materials have attracted numerous attentions due to their kinds of various and implications in many areas. Pyrene and BODIPYs are two of the most noteworthy fluorescent materials. As popular fluorophores, pyrene-labeled molecules have many advantages such as the ratio between the emission intensities of the monomer and exeimer. relatively large fluorescence quantum yield and long lifetimes. On the basis of the intensity ratio of the monomer to the exeimer peaks, signal fluctuations can be cancelled, and the impact of environmental quenching can be minimized. Research in this area has been successful in the selective detection of ions, small molecules and DNA. However, their sensing mechanism is based on the complexation or hydrogen bonding interaction with the analyte. There is no example of a chemodosimeter based on the pyrene excimer/monomer transformation mechanism.BODIPY derivatives (BODIPYs or BDP) have attracted tremendous attention as fluorescence dyes due to their advantageous photophysical properties such as. large molar absorption coefficients, high fluorescence quantum yields, narrow absorption and emission bands, low sensitivity to the polarity of the solvent and pH, moderate redox potential, long fluorescent life and excellent photochemical stabilities. Since they have superior spectral characteristics to those of fluoresceins and rhodamines. BODIPYs have already started to be used in some contexts. However, BODIPY dyes with efficient fluorescence in the solid state are rare, the fluorescence in the solid-state is effectively suppressed due to flat-conjugated systems in molecular structures, efficient emission of molecules in the solid state is prerequisite to the fabrication of molecular devices. Modified in different positions of BOD1PY core show interesting spectra phenomenon, little research and reporting in-depth about the mechanism of this phenomenon.To solve the above problems, some specific fluorescent dyes were designed and synthesized, which exhibited interesting spectroscopic properties. For example, first chemodosimeter fluorine ion probe was designed based on the pyrene excimer/monomer transformation mechanism; BODIPY dimers with phenyl and bulky triphenylsilylphenyl substituents were synthesized, which showed effective emission in solid state:a family of2. 6-styryl substituted BODIPY dyes have been synthesized and characterized by X-ray diffraction, photophysical studies and theory.The main research results are as follows:1. Two pyrene dimers containing an-O-Si-Si-O-or-O-Si-O-linkage have been designed which exhibit ratiometric excimer/monomer emission upon fluoride anion induced Si-O bond cleavage. Incorporation of the probe into water soluble polymeric nanoparticles enhances its intracellular uptake and displays ratiometric fluorescent. This is first fluorine ion probe of a chemodosimeter reaction-based on the pyrene excimer/monomer transformation mechanism2. A borondipyrromethene (BODIPY) derivative bearing a hydroxymethyl group at the meso-position can act as a fluorescence turn-off chemosensor for hypochlorite in aqueous media with high sensitivity, a rapid response time, and high selectivity in the presence of other ions and oxidative molecules. Moreover, confocal fluorescence microscopy experiments have established the utility of BODIPY-CH2O11for monitoring the presence of hypochlorous acid in living cells3. BODIPY dimers with phenyl and bulky triphenylsilylphenyl substituents are synthesized through oxidative self-coupling of the2-position with FeCl3. Spectroscopic properties of all the dyes in various solvents and on films have been investigated. In comparison with the corresponding monomers, the dimers exhibit higher molar absorption coefficients, relative moderate fluorescent quantum yields and redshifted wavelengths. The luminescence yields of the dimers are solvent polarity dependent and decrease dramatically in acetonitrile. More intensive solidstate emission of triphenylsilylphenyl substituted BODIPY dimer is observed with a quantum yield of9.7%relative to the phenyl substituted dimer. which could be attributed to the introduction of the bulky group that inhibits aggregation.4.2,6-Styryl substituted BODIPY is synthesized throught Heck reaction. Comparing with1,7-and3,5-styryl substituted BODIPY,2,6-styryl BODIPY exhibits a large Stokes shift and low quanyum yield. TD-DFT is carried out to evaluate the spectroscopic characteristics using the conformation change between the the ground state and the excited state. The use of P-dimethylaminostyrene. three novel BODIPY isomers are isolated and showed interesting photophysical properties and could be as sensors for pH. Our research demonstrate the dominant role of styryl rotation and intramolecular charge transfer in governing the fluorescence properties of these dyes.