Syntheses And Properties Of Rhodamine 6G-and Seminaphthorhodafluor-based Fluorescence Probes

In recent years,due to the ecological cycling and environmental pollution,recognizing and detecting heavy metals have been playing an increasingly important role in the application of biological systems and host-guest chemistry.Therefore,the designing of fluorescent probes with excellent selectivity,supernal sensitivity,nondestructive and low cost has always been a hot subject,and the probes are supposed to be simple and quick in time and space sampling and situ detection.Copper is a necessary trace element in many biological processes and systems.It plays an important role in biochemical reactions such as catalysis,transportation and biosynthesis at trace level.But the high concentration of copper ions is highly toxic to organisms and threaten the healthy development of the ecosystem.Mercury is one of the most toxic and dangerous contaminants to the environment and the biota,with recognized characteristics such as cumulative arid persistent.Hence,many research fellows are committed to designing and synthesizing chemical sensors which can detect Cu2+ and Hg2+ in environment and organisms.This is of great significance for environment protection and human health.Many of the fluorescent probes for single term sensing of Cu2+ or Hg2+ have been published,but few of them can be used to detect Cu2+ and Hg2+ simultaneously by different methods.At present,many researchers are devoted to combining probes with medical clinical and biological applications.Near infrared direction probes will be one of the research highlights in the future.In this paper,two new fluorescent molecular probes have been designed and synthesized from different parent bodies.The main contents of the research are as follows:(1)A new dual channel fluorescence probe,R6GB,was obtained from the reaction of hydrazine hydrate and 2-formylphenyboronic acid with rhodamine 6G as the parent.The probe is insensitive to pH and can be used in a wider range of pH environment.The Cu2+ can be identified specifically in the CH3CH2OH/H2O(7:3,v/v)with UV-vis absorbance spectra and the absorbance wavelength is 528 nm.The color changes from colorless to pink in the detection process.The limit of detection is 5.75×10-8 mol/L and the association constant is 2.25×105 M-1.The probe can identify the Hg2+ specifically in deionized water with fluorescence spectrum and the emission wavelength is 543 nm.The limit of detection is 2.78×10-8 mol/L and the association constant is 6.03 ×105 M-1.The complex-ratio of the probe to Cu2+ and Hg2+ was 1:1 in accordance with Job's experiment as well as spectral titration analysis,and the possible complexation mechanism of R6GB to Cu2+ and Hg2+ was also conjectured.(2)A new fluorescence probe named SNARFB was obtained from the reaction of hydrazine hydrate and 2-formylphenyboronic acid with the seminaphthorhodafluor derivative as a parent.The probe can identify Cu2+ specifically in CH3CN/H2O(3:7,v/v),which is almost undisturbed by other metal ions.The solution was transformed from colorless to purple after addition of Cu2+.The detection is in the range of 3.72×10-6 mol/L-1.77×10-7 mol/L and the binding constant is 1.73×104 M-1.The complexation ratio of the probe with Cu2+ is 1:1 concluded by Jobis plot experiment and spectral titration analysis.The maximum peak values of the UV-vis absorption spectrum and the fluorescence emission spectrum of the probe are 550 nm and 579 nm respectively.It has a great potential in biological applications such as fluorescence labeling and tracer.