Synthesis And Properties Of Pyronin-Based Fluorescent Probe For Phosgene

The choice of the fluorophore is an important part of the property of probe in the field of fluorescent probe. Now, there are many fluorophores have been used in fluorescent probe, and their synthetic methods are formed. Although rhodamine and pyronin are belong to different classes, they have the same fluorescence changes in the structure from xanthene to pyronin. The off-on of the spiro-ring is the key reaction of fluorescence response based-on rhodamine. The pyronin is mainly depend on the PET effect as luminescent mechanism. Pyronin have excellent photophysical properties, high fluorescence quantum yield, molar absorption coeffcient is greater than 5×104 L·mol-1·cm-1, and the C9 is high reactivity, the different elements derivatives could covert to each other, have the advantages of easy to modify.In this study, we choose rhodamine and pyronin as the fluorophore, introduce appropriate substituent to make proper modification, synthesized 12 compounds of rhodamines and 8 of pyronins. And choose the toxic gas as the detection target, then explore the various performance of the probes and want to develop the probe that have excellent performance and specificity response to phosgene. We also explored the improve synthesis methods of oxo-and sulfo-xanthene, do some basic works to synthesis of pyronin derivatives that more simple and higher yield. Main content includes:1. Developed the simply method to synthesis of oxo-and sulfo-xanthene. In the presence of potassium tert-butoxide, the pyronin could react well with elemental oxygen and sulfur to obtain the oxo-and sulfo-xanthene in high yield. Under certain conditions, they could conversion to each other, the convert ratio is over 90%.2. Developed the simple and efficient method to synthesis of the pyronin derivatives based on oxo-and sulfo-xanthene. The synthesis of pyronin derivatives are simply finished by sulfo-xanthene with electrophilic reagent (mainly halohydrocarbon) and nucleophilic reagents (mainly amine), yields were greater than 70%.3. The compound of PY-OPD is a fluorescent probe for selectivity and sensitivity detection of phosgene, the detection limit achieved to 6.6×10-9 M. The results show that the PY-OPD almost nonfluorescent is mainly because of the PET effect between o-phenylenediamine group and pyronin fluorophore. When reacted with phosgene, intramolecular cyclization reaction is caused, and the product is amide group that could remove the PET effect from the amino group, so the red fluorescence of pyronin is recovered. The secondary amine groups of compound PY-PPD and PY-PA are amide-type, they could not react with phosgene and the PET effect is continue to persist, and could not to recognition the phosgene.