Synthesis And Ion Recognition Of Rhodamin Derivative Based Probes

Molecular recognition to establish bionics system and chemical model by synthetic new artificial chemosensors. In recent years, since the method of the molecular recognition is fast and efficient in organism and environment, it has attracted more and more attention. UV and fluorescence spectrum analysis methods are one of the important recognition methods to detect all kinds of metal ions, because of its good selectivity, sensitive and the naked eye recognition. Rhodamine dyes often feature a long emission wavelength, high fluorescence quantum yields, and high molar extinction coefficient, which offers additional advantages for the design of probes to detection of metal ions. In this thesis, a series of new probes based on rhodamin derivative were synthesized and investigated for detection of iron(II),copper,zinc,mercury and aluminum. The details are as follows:1、The concept of molecular recognition and the principles of designing probes were briefly introduced. In recent years, probes based on rhodamine derivatives for detection of metal ions are summarized.2、Probe Rh1 containing DPA structre has been synthesized as a high selevtive recogrition probe for Fe2+ in CH3CH2OH-H2O(1:1, v/v, HEPES 20 mM, pH = 7.4) solution. Fe2+ induced the spirolactam ring of probe Rh1 open and caused significant fluorescence intensity changes. A 1:2 stoichiometry was most possible for the binding mode of Rh1 and Fe2+ and the association constants of 2.04×104 M-1. During the recognition process, other metal ions did not cause any discernible changes except Mn2+ and Cd2+ inducing a small enhancement.3、Tow new probes Rh2 and Rh3 based on Rhodamine B have been synthesized with 2,4-dihydroxybenzaldehyde derivatives. Due to the ether chain of probes, the solubility of Rh2 and Rh3 are improved. In CH3CH2OH-H2O(3:7, v/v, HEPES 20 mM, pH = 7.4) and CH3CH2OH-H2O(2:8, v/v, HEPES 20 mM, pH = 7.4) solution, Rh2 and Rh3 exhibited high selectiveity to Cu2+ with colormetric detection, respectively. The color changes from colorless to pink was naked eye observable. The recognition process of two probes are barely interfered by other coexisting metal ions. Probes bind Cu2+ via a 1:1 stoichiometry with the association constants of 9.81×105 M-1 and 1.95×106 M-1.4 、 Rhodamin B hydrazide with 8-hydroxy-2-quinolinecarboxaldehyde and 3-acetyl-4-hydroxyl coumarin Schiff probes Rh4 and Rh5 have been synthesized, respectively. Both probes can detection of different ions by changing the applied solvent system. In DMSO-H2O(5:95, v/v, HEPES 20 mM, pH = 7.4) solution, Rh4 as a colorimetric and fluorescent probe for detection of Hg2+, and in CH3CN-H2O(1:1, v/v, HEPES 20 mM, pH = 7.4) solution, Rh4 as a fluorescent probe for the recognition of Cu2+. But Rh5 displayed high selective toward Al3+ in CH3CH2 OH solution, and displayed high selective toward Zn2+ in CH3 CN. The competition experiments demonstrated that the ions recognition event is hardly hamped by other metal ions.