The Synthesis And Application Of Novel Naphtho[b]-fused BODIPYs

Boron dipyrromethene(BODIPY)dyes have been widely used as fluorophores in fluorescent sensors,biological labeling,photodynamic therapy and organic light-emitting diodes(OLEDs)due to their excellent photophysical properties,such as high photostability,sharp fluorescence emission,high fluorescence quantum yields(?f>0.5)and large molar absorption coefficients.Conventional BODIPY dyes generally absorb and emit in the range of 470-530 nm.However,the absorption and emission in the near-infrared(NIR)range is more favorablein consideration of various practical applications of BODIPY dyes.To this end,several methods have been adopted to modify the BODIPY core,such as aryl substitution at peripheral positions,substitution of a carbon atom with a nitrogen atom at the meso position and aromatic ring fusion.Among them,fusion with aromatic rings such as benzene,naphthalene,phenanthrene,thiophene and furan has the advantage of extending the?system and reducing the nonradiative decay through restrict rotational relaxation.These synthetic methods have the following problems:(1)Most of the reported BODIPYs are symmetric and it is difficult to be further modificated with analyte-active group;(2)Aromatic ring-fused pyrrole is unstable and difficult to modify and synthesize;(3)It is generally more complex and difficult for the aromatic-ring fused BODIPY to be synthesized.Therefore,this paper mainly did research on the following three aspects:(1)We have developed a series of novel naphthalene ring fused BODIPYs.BODIPYs with one and two naphthalene rings fused at the b position have been synthesized from iodo-substituted BODIPYs and(2-formylphenyl)boronic acid through Suzuki-Miyaura-Knoevenagel one pot reaction with moderate yields.The structure of the compound was characterized and its optical properties were studied.The fusion of the naphthalene ring greatly extends the?-conjugation of BODIPY 3(?abs=630 nm)and thus made it exhibit NIR absorption.Theoretical calculations suggest that naphthalene-fused BODIPYs display markedly stabilized LUMO energy,which can be used in the field of optoelectronics such as electron transport materials.The methyl group at the 5-position of the asymmetric BODIPY 2a can be further modified with the analyte-active group to fabricate novel NIR chemosensors.(2)The universality of the new methods was studied in detail.Various meso-substituents with different electronic structure,such as 4-cyano,4-tert-butyl,2,4,6-trimethyl,were employed to synthesis the new naphthalene-fused BODIPY a,b and c.The structure of the compounds were characterized and the spectra were recorded.It can be concluded that electron donating group on the meso-position may accelerate the one-pot Suzuki-Miyaura-Knoevenagel reaction,and increase the yield of the target molecules.(3)Analyte-active groups can be introduced into 5-positions of the novel naphthalene-fused BODIPYs.BODIPY probes M with Si-O group in the 5-position,have been successfully synthesized and characterized.Owing to the strong affinity between fluoride and silicon,this probes exhibit high selectivity for F~-relative to various other anions.In the presence of F~-,the emission of the probes was quenched.The UV-Vis absorption of M redshifted 100 nm and reached into the NIR region(716nm).Confocal fluorescence microscopy experiment demonstrated that BODIPY M can be used to monitor fluoride in living cells.