Applications of Fluorescent Sensor Based on 1H-pyrazolo[3,4-b]quinoline in Analytical Chemistry

Fluorescent dye 2-[(2-Hydroxyethyl)-(1,3-diphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amino]ethanol (LL1) was examined for its efficiency in the detection of small inorganic cations (lithium, sodium, barium, calcium, magnesium, cadmium, lead and zinc). The dye was synthesized in the laboratory and investigated by means of both, steady-state and time-resolved fluorescence techniques. This compound acts as a fluorescent sensor suitable for detection of small inorganic cations (lithium, sodium, barium, calcium, magnesium, cadmium, lead and zinc) in strongly polar solvent (acetonitrile). An electron transfer from the electro-donative part (receptor) of the molecule to the acceptor part (fluorophore) is thought to be the main mechanism that underlies functionality of the compound as a sensor. This process can be retarded upon complexation of the receptor moiety by inorganic cations. Relatively high sensitivity but poor selectivity of the aminoalcohol thatcontains indicator towards the two-valued cations was observed. However, upon addition of some amounts of water the selectivity of this sensor has been enhanced (especially towards lead cation). The preliminary results in analytical application of the sensor are discussed.