Design, Synthesis, And Spectroscopic Properties Of Thiophene-fused Bodipy Fluorescent Dyes

Many detection methods are applied to the research of modern biotechnology and life sciences.Because of low detectability, good sensitivity and selectivity, fluorescence analysis technology has playedan irreplaceable role in the bioanalytical field.4,4’-difluoro-4-bora-3a,4a-diaza-s-indacene (abbreviated asBODIPY) dyes are well-known to have intense absorption, excellent thermal and photochemical stability,and high quantum yield. BODIPY dyes acted as good candidates for biological labeling, electroluminescentfilms and fluorescent probes. Therefore design and synthesis of novel BODIPY dyes have been attarctingincreasing interest.Utilizing the thieno[3,2-b]pyrrole, we succesfully synthesized a series of non-symmetricthiophene-fused BODIPY8a-9d.2-thenaldehyde3a,3b and ethyl azidoacetate were used as the startingmaterial, and ethyl thieno[3,2-b]pyrrole-5-carboxylate4a (50%),4b (42%) were synthesized, based onHemetsberger–Knittel reaction.6a,6b were obtained in50,32%yield by the reduction and oxidation of4a,4b. Then,6a,6b reacted with pyrrole7to give BODIPY8a-9d in21-63%yields. The absorption andemission maxima of such BODIPY dyes (λabs=532-647nm; λem=547-664nm; ΦF=0.19-0.45) coveredthe visible-near-infrared region. The tunable emission wavelengths were achieved by the modification of8a:BODIPY8a (λem=547nm) reacted with m-CPBA to give the thiophene-1,1-dioxide derivative10(λem=528nm), along with the blue shift (19nm); BODIPY8a undertook a Knoevenagel-type condensation togive BODIPY12(λem=693nm) and the remarkable redshift (146nm) was achieved. In addition,thiophene-fused BODIPY dimer and thiophene-fused BODIPY-based fluorescent probe for thiophenolswere designed and synthesized.Moreover, other novel BODIPY fluorescent dyes were designed and synthesized. First, novel aza-BODIPY fluorescent dye21(λabs=695nm) was synthesized. Second, novel BODIPY-based fluorescentprobe TM-BODIPY-CH2N3for hydrogen sulfide was synthesized, and the fluorescence quenched utilizinghydrogen sulfide-triggered reduction of azide to amine. However, methyl BODIPY TM-BODIPY-CH3wasobtained, the reaction mechanism is in progress.