NAD(P)H: quinone oxidoreductase 1 activatable toll-like receptor 7/8 agonist designed for precise immunotherapy.

An NQO1-responsive precursor, named R848-QPA, has been developed to evoke an anti-tumor immune response. R848-QPA can induce innate immune activation when activated by overexpressed NQO1 in the tumor microenvironment while showing lower activity in NQO1-deprived environments. This strategy provides a new method for the development of tumor-microenvironment-responsive prodrugs for antitumor immunotherapy.

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 job's 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.

Several hemicyanine dyes as fluorescence chemosensors for cyanide anions.

Four hemicyanine dyes as chemosensors for cyanide anions were synthesized easily. Their photophysical properties and recognition properties for cyanide anions were investigated. The results indicate that all the dyes can recognize cyanide anions with obvious color, absorption and fluorescence change. The recognition mechanism analysis basing on in situ (1)H NMR and Job plot data indicates that to the compounds with hydroxyl group, the recognition mechanism is intramolecular hydrogen bonding interaction. However, to the compounds without hydroxyl group, cyanide anion is bonded to carbon-carbon double bond in conjugated bridge and induces N(+)CH3 to neutral NCH3. Fluorescence of the compounds is almost quenched upon the addition of cyanide anions.

Coumarin benzothiazole derivatives as chemosensors for cyanide anions.

Four coumarin benzothiazole derivatives, N-(benzo[d]thiazol-2-yl)-2-oxo-2H-chromene-3-carboxamide (1), (Z)-N-(3-methylbenzo[d]thiazol-2(3H)-ylidene)-2-oxo-2H-chromene-3-carboxamide (2), 7-(diethylamino)-N-(benzo[d]thiazol-2-yl)-2-oxo-2H-chromene-3-carboxamide (3) and (Z)-7-(diethylamino)-N-(3-methylbenzo[d]thiazol-2(3H)-ylidene)-2-oxo-2H-chromene-3-carboxamide) (4), have been synthesized. Their crystal structures, photophysical properties in acetonitrile and recognition properties for cyanide anions have been investigated. All the compounds are generally planar, especially compound 1 exhibits perfect planarity with dihedral angle between benzothiazolyl group and coumarin group being only 3.63°. Coumarin benzothiazole compounds 1 and 3 can recognize cyanide anions by Michael addition reaction and compound 3 exhibits color change from yellow to colorless and green fluorescence was quenched completely, which can be observed by naked eye. Coumarin benzothiazolyliden compound 4 can recognize cyanide anions with fluorescence turn-on response based on the copper complex ensemble displacement mechanism.