Studies On The Design And Synthesis Of New Fluorescent Probes Based On Pyrazoline And Their Recognizing And Sensing Properties For Metal Ions

Fluorescent probe is widely used as powerful tools to spy on metal cations、anion andneutral molecules owing to their high selectivity, sensitivity and relatively simple handling.The design of an efficient fluorescent probe for specific analyte has received a growingattention.1,3,5-Triaryl-2-pyrazolines, with their rigid but only partly unsaturated centralpyrazoline ring, are well-known fluorescent compounds widely used in fluorescence dyesemitting blue fluorescence with high fluorescence quantum yield; additionally thesecompounds have found application in electroluminescence. However, only a few exampleshave been reported on the interactions between pyrazoline derivatives and metal ions. In thisdissertation, the efforts were focusd on design and synthesis of new pyrazoline derivativesand their molecular recognition and sensing for metal ions. A series of significative resultshave been obtained. The main contents are shown as following:1. A detailed review was carried out about the background related to this work, such as thestructure of fluorescent probe, various fluorescent sensing mechanisams and research offluorescent probe based on pyrazoleline. We put forward our design ideas and research topicsbased on the above review.2. Two simple pyrazoline derivatives1a and1b were designed and synthesized. Thestructure and conformation of1a was confirmed by single crystal X-ray diffraction. Theirphotophysical properties were studied by absorption and fluorescence spectra. The compound1a can be used to determine Cu²⁺ion with high selectivity and sensitivity among a series ofcations in aqueous tetrahydrofuran. In contrast to1a compound1b, which has no hydroxylgroup in the phenyl ring did not revealed any significant changes in absorption andfluorescence emissions upon addition to copper ion, which indicates the importance of aphenolic group as a binding site at the3position of the pyrazoline ring.3. Two new pyrazoline derivatives2a and2b were designed and synthesized. The structureand conformation of2a was also confirmed by single crystal X-ray diffraction. Thechemosensory properties studied by UV and fluorescent spectroscope showed that both2a and2b can selective recognition towards Fe³⁺among other metal ions in THF with fluorescencequenching, and formed1:1stoichiometry complex with Fe³⁺. The study also showed that the benzothiazole group of2a have not cruial effect on the interactions between compound2a andFe³⁺.4. A new pyrazoline derivate3with coumarin group and benzothiazole group attached topyrazoline ring was designed and synthesized. Its binding properties investigated in theanquous EtOH by UV and fluorescence spectroscope showed that it can selectively bind Co²⁺and Ni²⁺with fluorescence quenching, and formed1:1stoichiometry complex with Co²⁺andNi²⁺. Moreover, the change of IR spectroscope of3indicates the importance of carbonylgroup of coumarin unit in as a binding site for Co²⁺and Ni²⁺.