Spirolactam Ring-opening System Of Rhodamine Derivative Utilized As Fluorescence-enhanced Sensor

Fluorescent sensor has been widely utilized in the area of chemistry, environmental science and biological science, due to its specific selectivity, high sensitivity, fast response and convenient application. With the fluorescence-enhanced signal, they can well avoid the interference and give more exact information that has attracted considerable attention. The spirolactam-ring opening system of rhodamine derivative would provide an excellent platform for the design and synthesis of fluorescence-enhanced sensor.Based on the well affinity of allyl group to Pd, we introduce bi-allyl hydrazine ligand into the spirolactam-ring of rhodamine to design and synthesize a fluorescence-enhanced sensor RPdl. It displays both fluorometric and colorimetric methods specific for Pd2+ with detection limit of 185 nM, which can be used for residual Pd detection in reactor and can also be loaded as test paper for optical detection of Pd2+ in ppm levels in 100% water solution.We next use the allylidene-hydrazone group to get more conjugacy than the allyl-hydrazine group in RPdl and adjust their electron density with methyl and bi-cyano group in RPd2 and RPd3. They both show excellent selectivity for Pd2+ with detection limit of 185 nM and 1.7μM, respectively, without Hg2+ interference. With richer electron density and more suitable stereo effect in the ligand, RPd2 behaves high sensitivity and good anti-jamming ability which shows the potential application for Pd-contaminated water and soil samples analysis.The tridentate PNO ligand combined both hard and soft donor atoms was adopted to develop RPd4 which displays a high sensitivity and very fast response to Pd2+. It can detect as low as 5 nM Pd2+ with the association constant of 2.39×105 M-1 and a short balance time about 10 s in ethanol. It can avoid the interferences from other cations and anions with excellent reversibility. RPd4 can be used for trace Pd analysis in real samples such as drug, water, soil, leaf and so on.On the basis of different reactions of a,(3-unsaturated aldehyde group with Cys and Hcy, we design and synthesize a fluorescence-enhanced sensor RS1 which can effectively discriminate Cys from Hcy, GSH, LPA and other common biomolecules, with detection limit of 73.5 nM. RS1 can be used for Cys content evaluation in human urine and Cys imaging in living cells which can provide valuable information for the diagnosis of related illness.