Design, Preparation And Properties Of Copper Chemosensors Based On Rhodamine

With the continuous development of the society, people enjoy a high quality life,at the same time the heavy metal pollution caused by industrial production graduallyattracted great attention of the whole society. Many mass poisoning incidents havetaken place, so establish the metal ion detection and control technology is particularlyimportant and urgent. There are so many analytical techniques have been used fordetecting mental ions, however these methods always need expensiveinstrumentations, and exist some disadvantages. The advantages of fluorescencechemosensors are easy to operate, high selectivity and good sensitivity. Whilecolorimetric sensors are prevalent due to their capability to detect metal ions vianaked eye, and can be used for on-site testing. Among the transition metal ions,copper ion is the third most adequate and plays important roles in biological such ashemoglobin biosynthesis, bone development. However, excessive accumulation ofCu2+in the human body will cause neurodegenerative diseases, and then causedmetabolic disturbance, liver cirrhosis and liver ascites even more serious diseases. Sohere we designed chemosensors for detecting copper ions.1. A novel fluorescent/colorimetric rhodamine copper chemosensor was designed.We use aniline and salicylaldehy as starting materials to get intermediate2,rhodamineB and hydrazine to get intermediate3. Intermediate2and3occurred Schiffbase reaction to obtain sensor1. Sensor1showed good selectivity to Cu2+inEtOH-H2O (1:10) solution. Upon addition of Cu2+, an obvious fluorescenceenhancement was observed at575nm and a new ultraviolet absorption appeared at560nm, while other mental ions showed no obvious interference. An apparent colorchange was observed from light yellow to red and fluorescence from colorless toorange-yellow. This sensor displayed very high sensitivity and short response time.The detection limit for Cu2+in water was found to be7.2×10-7molL-1(based on S/N=3).2. A detection system which had concentration gradient colorimetric detectioneffect to copper ion was designed. It was composed of rhodamine derivatives (sensor1)and menadione derivatives (sensor2). With titration of Cu2+, sensor1had a newultraviolet absorption at560nm and color change from white to pink, sensor2colorchange from orange to blue and the absorption band at476nm diminished at the sametime the absorption at644nm gradually increased. In this paper, we use rhodamineand menadione probes they are both have obvious color change to get a detectionsymtem in DMF:H2O (1:1，v/v) pH7.0510mM Tris-HCl buffer. Upon addition ofCu2+, firstly a new absorption band observed at560nm with increasing intensity andthen another absorption appeared at644nm with increasing intensity, at the same timethe absorption band at476nm diminished. Through changing the proportion of sensor1/sensor2from1:1to1:10we found that when the molar ratio was1:8we could getthe best detection result. Now, we could observe elaborate color change from lightorange to pink and last to purple via naked eye.