| Conjugated compounds with small molecular weight and fluorescent property, would be used as chemsensing materials. This area attracts more and more attention in recent years. Electron transfer would occur when fluorescent compound with rich electrons contacting with nitro-explosives, which are lack of electrons in their molecular structure. As a result, the fluorescence intensity decreases in this system. According to the principle of electron transfer, small fluorescent compounds dissolved in solvents or spun on glass can be used for explosives detecting in practice.9-ethynyl-9-hydroxyanthrone, a novel fluorescent compound, was synthesized via the deprotection of trimethylsilyl under base catalysis, after the nucleophilic addition reaction of anthraquinone by lithium(trimethylsilyl)acetylide. The optimal conditions show as follows: the temperature of nucleophilic addition and removing trimethylsilyl are 45℃-50℃and 25℃-30℃, respectively, as well as the time of these reactions are 48 hours and 24 hours, respectively. In this condition, the final yield reaches to 15%-18%. Its structure has been confirmed via IR,1H NMR, LC-MS and element analysis. The melting point, crystal, UV spectra, the maximum excitation wavelength and emission wavelength of 9-ethynyl-9-hydroxyanthrone were obtained.The molecular structure, distribution of charge, electrostatic potential and chemical reactivity of target molecule were calculated by quantum chemistry under the level of B3LYP/6-31g(d, p). The results were consistent with the data observed in experiment.The 9-ethynyl-9-hydroxyanthrone chloroform solution emits blue light under UV light at 254 nm. The maximum excitation wavelength and emission wavelength were estimated under 1.1 mmol/L 9-ethynyl-9-hydroxyanthrone in chloroform, i.e.376 nm and 443 nm respectively. The emission spectra of 9-ethynyl-9-hydroxyanthrone has been investigated in chroloform and methanol. Fluorescence intensity of the former is higher than that of the latter, so it can be assumed that the fluorescence intensity might be weaken in protic solvents. Fluorescence quenching of TNT and HMX to 9-ethynyl-9-hydroxyanthrone at different time have been determined. More over, the fluorescence quenching of TNT to 9-ethynyl-9-hydroxyanthrone at different concentrations also have been investigated. The results showed that TNT can quench the fluorescence of 9-ethynyl-9-hydroxyanthrone obviously, and HMX had the same quenching effect. In our observation, TNT and HMX can quench its fluorescence within 15 minutes, but the process was a bit of difference. However, the quenching time of the former was shorter than that of the latter, so we could conclude that a conjugated ring exsiting in TNT might accept more electrons which transfered from the fluorescence compound. The detection limit of TNT to this fluorescence compound is 1.57×10-8 g/L.The fluorescence response to 9-ethynyl-9-hydroxyanthrone also was investigated under methanol and acetone, and they can quench the fluorescence intensity lightly. Under the excitation wavelength of 376 nm, the emission spectra of anthraquinone in chloroform could not be observed from 400 nm to 700 nm, hence a bit of crude material would not interfere the emission spectra of fluorescence compound in our quenching experiments.From the process of synthesis and its properties, we know that a chromophore group and ethynyl group with active property exsit in 9-ethynyl-9-hydroxyanthrone, which has conjugated ring structure in its structure. As a result, it has some fluorescence properties, and could be used as sensing material for detecting explosive. Hence this kind of materials has potential application in nitro-explosives detection. |
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