Synthesis, Optical Properties And Application Of Novel BODIPY Fluorescent Chemosensors

Many metal cations and anions have considerable vital roles in the biological system and the environment. However, excessive intake will cause some toxicity and diseases. Therefore, the development of the detection for these ions is a very important for scientific research and practical application. Fluorescent sensors have attracted much attention due to their high selectivity, high sensitivity, real time monitoring, simple and efficient detection. Currently, they are widely applied in the detection of metal cations and anions in the environment, food, and biological system.BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) is one of the most interesting signaling subunits in the artificial fluorescent sensors due to its remarkable photophysical properties, such as strong absorption and emission in the visible region, high fluorescence quantum yield, high molar absorption coefficients, and photochemical stability. Moreover, BODIPY has an amenability to structural modification, which makes the absorption and emission bands of BODIPY easily tune to near infra-red(NIR) or red spectral range.Keeping those thoughts in mind, we designed and synthesized a series of new BODIPY-based fluorescent sensors with different receptors in this article by modification of 3,5 positions of BODIPY core. We investigated the ions detection of these fluorescent sensors by using UV absorption and fluorescence spectroscopy, and eventually applied these fluorescent sensors in molecular logic gate.1. Firstly, we synthesized a novel BODIPY-based fluorescent sensor S1 with an urea group. Upon addition of F-ions, the maximum absorption band of S1 in CHCl3 displayed a red shift from 581 to 588 nm, which was visually manifested as a color change from pink to blue. When excited at 550 nm, the fluorescent emission intensity of S1 at 608 nm was quenched to over 87%. Moreover, we found that the S1-Fcomplex was reversible upon addition of HSO4- ions. By using F- and HSO4- ions as chemical inputs and the absorbance and fluorescence intensity as outputs, a complementary INHIBIT/IMPLICATION(INH/IMP) logic gate was constructed at the nanoscale level.2. Secondly, we reported a new BODIPY-based chemosensor Se-1 that could achieve double-channel detection of Hg2+ and Cu2+. Se-1 showed high selectivity and sensitivity toward Hg2+ and Cu2+ in CH3 CN, which induced color changes from pink to purple and blue. The fluorescence spectra showed fluorescence enhancement and migrated to different extent after complex of Se-1 and Hg2+ or Cu2+(Hg2+: a blue shift of 2 nm; Cu2+: a redshift of 15 nm). The absorption and fluorescence of the Se-1–Hg2+ complex could be reversibly restored to that of the uncomplexed ligand by using EDTA or cysteine, however, the sensing processing of Se-1 in response to Cu2+ ions could not. Thus, we constructed a YES/INH molecular logic gate based on the reversible behavior of Se-1 and Hg2+.3. Finally, we synthesized and characterized a novel near-infrared fluorescent chemosensor containing two ethynylpyridine groups based on BODIPY(Py-1). Py-1 displayed high selectivity and sensitivity for sensing Cu2+ over other metal ions in acetonitrile. When Py-1 is excited at 600 nm in the presence of Cu2+, the fluorescent emission intensity of Py-1 at 617 nm is quenched over 86%. Interestingly, the complex of Py-1-Cu2+ is chemical reversibility. This system could be used as IMP logic circuits and integrated into a feedback loop by mimicking the“Set-Reset”molecular level encoded information processing devices.