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Study Of Near-Infrared BODIPY Fluorescent Probes For PH

Posted on:2013-07-11Degree:MasterType:Thesis
Country:ChinaCandidate:P C ShiFull Text:PDF
GTID:2231330371489665Subject:Organic Chemistry
Abstract/Summary:PDF Full Text Request
4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (here after abbreviated to BODIPY) dyes have excellentphotophysics and photochemistry properties such as high molar extinction coefficient, high stability againstlight and chemical reactions, and high fluorescence quantum yields, etc.Near-infrared (NIR) dye with thespectral fluorescent emission range between650-900nm (so-called optical window) has great advantages:significant reduction of the background absorption, fluorescence, low light scattering, the detectablesensitivity and selectivity, and deep penetration of the NIR light. Near-infrared (NIR) dye based onBODIPY have been attracting increasing interest.A series of BODIPYs1-12with dialkylaminophenylbuta-1,3-dienyl group were successfullysynthesized by a Knoevenagel-type condensationin36-42%yields. The absorption and emission maxima(λabs=614-739nm; λem=655-776nm in CHCl3) of such species1-12covered the visiblen ear-infraredregion. These dyes exhibited higher extinction coefficients ( and possessed abroader full width at half maximum (fwhm=57-90nm). In the investigation of the pH-responsiveproperties, probes1,2and5were almost non-fluorescent (Φf=0.0013-0.01) in DMSO/H2O (4:1, v/v).Upon the protonation of the tertiary amine function, the strong fluorescence was released (Φf=0.97for1; Φf=0.43for2; Φf=1for5) and the florescence intensity was dramatically increased by one thousandfold. The sharp isosbestic point is at590nm during the formation of the protonated compound1-H+. Due tothe difference of pKa of the substituent, the respond of1to the pH (pH=3) was more sensitive than that(pH=2) of5; upon the addition of HCl the enhancement of absorption and fluorescence intensity reachingthe maximum was2M HCl for1but4M for5. In the di-substituent system, the protonated compounds 2-H+and2-2H+were c distinguished in fluorescence spetrum (λem=663nm for2-H+; λem=597nm for2-2H+). The probe2was a turn-on NIR pH fluorescent probe.As a reference material of1,2and5, BODIPYs14-17with styryl group had been designed andsynthesized The absorption and emission maxima was slightly blueshifted compared with those of thecorresponding dyes with dialkylaminophenylbuta-1,3-dienyl group. In the investigation of thepH-responsive properties, probes16and17were lower fluorescent (Φf=0.030.02) in DMSO/H2O (4:1,v/v). Upon the protonation of the tertiary amine function, the strong fluorescence was released (Φf=0.67for1; Φf=0.45for2) and the florescence intensity was increased by ten and forty fold, respectively.
Keywords/Search Tags:sFluorescence, NIR Probe, BODIPY, pH sensor
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