Xueying Yu

Two 3-hydroxyflavone derivatives as two-photon fluorescence turn-on chemosensors for cysteine and homocysteine in living cells

Two 3-hydroxyflavone derivatives as one- and two-photon fluorescent chemosensors for cysteine (Cys) and homocysteine (Hcy) were synthesized. The recognition properties and mechanism of the chemosensors for Cys and Hcy were investigated systematically. The experiment results indicate that 3-hydroxyflavone compound 1 (6-bromo-2-(9-ethyl-9H-carbazol-3-yl)-3-hydroxy-chromen-4-one) after the addition of nickel ions exhibits good recognition properties for Cys and Hcy with fluorescence enhancement and 65nm absorption peak blue shift based on nickel displacement reaction mechanism. The detection limits (DL) with fluorescence as detected signal are 4.06 × 10-3µM (Cys, linear range of 10-80µM) and 5.8 × 10-3µM (Hcy, linear range of 10-100µM), respectively. But acrylate substituted 3-hydroxyflavone compound 2 (4-oxo-2-(4-diethylamino-phenyl)-4H-chromen-3-yl acrylate) can specially identify Cys with fluorescence turn-on (DL = 1.87 × 10-3µM, linear range of 4-22µM) based on Cys leading to acrylate hydrolysis mechanism and succedent excited-state intramolecular proton transfer process of 3-hydroxyflavone compound. Then Cys and Hcy biological thiols can be recognized at one time by these two 3-hydroxyflavone derivatives. The bioimaging experiment indicates that both the compounds can be successfully applied to the detection of Cys/Hcy in living cells and compound 2 also can be applied to bioimaging Cys in zebrafish by one- and two-photon fluorescence mode. Then these two compounds have a potential in the application of biological sample analysis.

Synthesis and cyanide anion recognition of a new displacement fluorescence chemosensor based on two-branched aurone

A new fluorescence turn-on chemosensor based on two dipyridylamine groups substituted aurone moiety, 4’-2,2’-dipyridylamine-3-2,2’-dipyridylamine aurone (1), was synthesized. The recognition properties of the compound for cyanide anions and copper ions were investigated. Yellow fluorescence of the compound is almost quenched completely because of the complexation between the compound and copper ions. After the subsequent addition of cyanide anions, fluorescence spectrum is recovered to the original status of the compound owing to the strong bonding ability between cyanide anions and copper ions and the removal of copper ions from the complexes. The recognition also can be observed by naked eye. The compound exhibits a good reversibility and can be used repeatedly to recognize cyanide anions for several times.

Two benzoyl coumarin amide fluorescence chemosensors for cyanide anions

Two new benzoyl coumarin amide derivatives with ortho hydroxyl benzoyl as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions in acetonitrile have also been examined. The influence of electron donating diethylamino group in coumarin ring and hydroxyl in benzoyl group on recognition properties was explored. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectral change and high sensitivity. The import of diethylamine group increases smartly the absorption ability and fluorescence intensity of the compound, which allows the recognition for cyanide anions can be observed by naked eyes. The in situ hydrogen nuclear magnetic resonance spectra combining photophysical properties change and jobs plot data confirm that Michael addition between the chemosensors and cyanide anions occurs. Molecular conjugation is interrupted, which leads to fluorescence quenching. At the same time, there is a certain extent hydrogen bond reaction between cyanide and hydroxyl group in the compounds, which is beneficial to the recognition.

A novel silicon-oxygen aurone derivative assisted by graphene oxide as fluorescence chemosensor for fluoride anions

A novel silicon-oxygen aurone derivative TBDPSA was synthesized and used for the detection of fluoride anions in aqueous solution based on a specifically F--triggered silicon-oxygen cleavage. Even though the compound has shown high selectivity, obvious absorption and fluorescence response for fluoride anions in aqueous solution, but it also is suffered from many limits, such as low detection sensitivity and long response time. Here the compound was successfully assembled on the graphene oxide (GO) surface by π-π stacking. GO improves recognition sensitivity and shortens response time of TBDPSA for fluoride anions by taking advantage of the nanocarrier GO. Compared with TBDPSA, the response time of GO/TBDPSA is shortened greatly from 1h to <5s and the detection limit is lowered about four times with fluorescence as detected signal. Generally speaking, GO is an excellent promoter for accelerate recognition.

Simple benzothiazole chemosensor for detection of cyanide anions via nucleophilic addition

A benzothiazolium salt containing carbazole group has been synthesized in a good yield via simple condensation reaction. Its photophysical properties and affinity for cyanide anion (tetrabutylammonium cyanide) have been investigated. The compound exhibited quick and well visible UV/Vis absorption and fluorescence responses to cyanide anion in MeCN, as the yellow color faded and the orange fluorescence disappeared. The in situ analysis by 1H NMR indicated that the cyanide anion was added to the C=N bond in the benzothiazolyl group.