Research On Fluorescent Probes For F~-based On Imidazolium Salts

The ion concentrations are important to biological processes such as metabolism in bodies, so detection and analysis of ions are necessary. In rescent years, fluorescent detection technology is widely applied in the field of ions detection, such an F-and Cu2+. But there are still many challenges:some fluorescent probes with modest selectivity, fluorescence quenching and detections only operated in organic slovent. A good fluorescence probe need not only an appropriate fluorophore, but also a matching receptor.Imidazolium salts can form a strong interaction with anions through (C-H)+...X-type hydrogen bond under the force of charge-charge electrostatic interaction because of its positive charge. In this thesis, a series of imidazolium salts for anions and small biological molecules were designed and synthesized, including mono-imidazolium salts and multi-imidazolium salts. The selectivity for anion guests have been studied and the mechanism has been discussed. Besides, based on this thesis group research to "two-armed" fluorescence probes on metal ions, a "one-arrmed" fluorescence enhanced Cu2+probes based on PET were designed and synthesized in this thesis.1. Three imidazolium derivatives, NBMZ-1, NBMZ-2, and NBMZ-3, were designed and synthesized for anions, in which naphthaimidazolium groups act as both fluorophore and anion receptor. From the results of UV-Vis spectra, fluorescence emission spectrum,1HNMR and19F NMR, it showed compound NBMZ-1exhibited high selectivity for F-over all the other anions in CH3CN solution and acted as a ratiometric fluorescent probe for F-with an enhanced blue-shift in emission.2. A cage type six-imidazolium salt, CSI-PF6, and a tripodal six-imidazolium salt, TASI-PF6(anthracene as fluorophore), were designed and synthesized based on phenyl group. From the results of1H NMR, it could be primely deduced that F-could be hosted in the cage. The recognition of TASI-PF6for twelve nucleotides was performed in buffered solution (HEPES,10mM, pH7.4) based on the absorption spectra and fluorescence spectra. ATP induced a more obvious fluorescence increasement, while GTP induced the most significant fluorescence quench.3. A bipodal two-imidazolium salt, CIP-PF6, a bipodal four-imidazolium salt, CDIP-PF6, were designed and synthesized derived from chiral trans-(1S,2S)-1,2-dioxyacenaphthene prepared by enzyme-catalyzed method, and pyrene as fluorophore. For CIP-PF6, the emission of pyrene dimer at477nm apperaed in pure CH3CN, and it declined sharply after the addition of F-and AcO-with the increase of the mono-pyrene emission. Moreover, other dectected anions caused no obvious changes. The recognition of twenty natrual amino acids was performed in buffered solution (HEPES,10mM, pH7.4) based on the absorption spectra and fluorescence spectra. The addition of L-Arg caused the decrease of absorbance and fluorescence intenstiy, while the addition of other amino acids did not induce obvious changes. For CDIP-PF6, in buffered solution (HEPES,10mM, pH7.4), the addition of CDP caused the decrease of absorbance and fluorescence intenstiy, while UTP brought a little enhance in fluorescence intenstiy.4. Based on PET and ICT, a fluorescent probe LZ-N was designed and synthesized with naphthalimide as fluorophore and N-butylbenzene-1,2-diamine as a new recognition moiety. The probe LZ-N exhibited high selectivity for Cu2+in aqueous media (CH3CN/H2O,1:1, v/v) colorimetricly and fluorescently, over all the other metal ions in our study. More than20-fold fluorescence intensity enhanced by coordinating with Cu2+. Cell viability values test and confocal fluorescence images showed little cytotoxicity and the high fluorescence enhancement of probe LZ-N, which made it possible to be applied to the detection of exogenous Cu2+in living cells.