Synthesis Of Carriers Such As Porphyrin, Naphthalimide And Their Application In Fluorescent Probe And Ion-selective Eletrodes

In recent years, the research on chemical sensors based on organic dyes remains very active and searching for new fluorophores to improve sensitivity and selectivity of chemical sensors is still a challenge for the analytical research efforts. In this thesis, a series of novel fluorescent probes and ion-selective carriers were designed and synthesized to determine pH, metal ions and anions. The contents of this thesis are presented as follows:1. The synthesis of a new compound, 10-(4-aminophenyl)-5,15-dimesitylcorrole, and its application for preparation of optical chemical pH sensors are described. The dye was immobilized in a sol–gel glass matrix and exposed to aqueous buffer solutions. The response of the sensor was studied which is based on the fluorescence intensity changing of corrole owing to multiple steps of protonation and deprotonation. Due to the presence of several proton sensitive centers, 10-(4-Aminophenyl)-5,15-dimesitylcorrole based optode shows wider response range toward pH than that of tetraphenylporphyrin(TPPH2) and 5,10,15-tris(pentafluorophenyl)corrole(H3(tpfc)). It shows a linear pH response in the range of 2.17-10.30. The effect of the composition of the sensor membrane has been studied and the experimental conditions are optimized. The optode shows good reproducibility and reversibility, and common co-existing inorganic ions did not show obvious interference to its pH measurement.2. A porphyrin derivative containing two 2-(oxymethyl)pyridine units has been designed and synthesized as chemosensor for recognition of metal ions. Unlike many common porphyrin derivatives that show response to different heavy metal ions, the porphyrin derivative exhibits unexpected ratiometric fluorescence response to Zn2+ with high selectivity. The response of the novel chemosensor to zinc was based on the porphyrin metallation with cooperating effect of 2-(oxymethyl)pyridine units. The change of fluorescence of the porphyrin derivative was attributed to the formation of an inclusion complex between porphyrin ring and Zn2+ by 1:1 complex ratio (K= 1.04×105), which has been utilized as the basis of the fabrication of the Zn2+-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Zn2+-sensitive chemosensor were investigated. The sensor can be applied to the quantification of Zn2+ with a linear range covering from 3.2×10?7 to 1.8×10?4 M and a detection limit of 5.5×10?8 M. The experimental results show that the response behavior of the porphyrin derivative to Zn2+ is pH-independent in medium condition (pH 4.0–8.0) with excellent selectivity for Zn2+ over transition metal cations.3. 2-{[(N-butyl-1,8-naphthalimide-4-yl)piperazine]methyl}-6-{[(anthracene-9- yl)-methyl-piperazine]-methyl}pyridine has been designed and synthesized to recognize Hg(II) in EtOH/H2O(1:1,v/v) solution, with naphthalimides-anthracene dyad selected as the fluorophore and a nitrogen-containing 2,6-bis(piperazine-1-yl-methyl) pyridine as the receptor. The new chemosensor for mercury was based on the well-known photoinduced electron-transfer (PET) mechanism and provided single-excitation, dual-emission detection. The dual fluorescence emission enhancement of the compound was attributed to the formation of an inclusion complex between 2,6-bis(piperazine-1-yl-methyl)pyridine unit and Hg(II) with a 1:1 complex ratio, which has been utilized as the basis of the fabrication of the Hg(II)-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Hg(II)-sensitive chemosensor were investigated. The sensor can be applied to the quantification of Hg(II) with a linear range covering from 2.4×10-7 to 8.6×10-5 M and a detection limit of 4.6×10-8 M. The experimental results show that the response behavior of the compound to Hg(II) is pH independent in medium condition (pH 5.0-8.0). And the proposed Hg(II)-sensitive chemosensor showed excellent selectivity for Hg(II) over other metal cations.4. The synthesis of a novel fluoroionophore containing naphthalimide and porphyrin and its application as a HgII-sensitive ratiometric fluorescent chemosensor are described. The realization of ratiometric signaling is based on developing a new stategy with two fluorophores (naphthalimide and porphyrin) in one molecule having the same excitation wavelength. The response of the chemosensor is based on the fluorescence ratiometric change of the compound by coordination with HgII and large shift between the two emission maxima (125 nm) with single excitation wavelength. The compound-based chemosensor shows a linear response toward HgII in the concentration range from 7.8×10-7 to 1.2×10-4 M with a detection limit of 8.0×10-8 M, and a working pH range from 4.0 to 8.0. The chemosensor shows excellent selectivity for HgII over other transition metal cations. Based on this, a highly sensitive and selective method for the determination of mercury was developed.5. An amide-linked 2,6-bis{[(2-hydroxy-5-tert-butylbenzyl)(pyridyl-2-methyl)- amino]-methyl}-4-methylphenol-ruthenium (II) tris(bipyridine) 2PF6- complex was first used to recognize Co(II) in EtOH/H2O(1:1,v/v) solution, with the ruthenium (II) tris(bipyridine) moiety selected as a fluorophore and the multi-substituted phenol unit chosen as a receptor. The fluorescence quenching of the compound was attributed to the formation of an inclusion complex between multi-substituted phenol unit and Co(II) by 1:1 complex ratio(K= 2.5×105), which has been utilized as the basis of the fabrication of the Co(II)-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Co(II)-sensitive chemosensor were investigated. The sensor can be applied to the quantification of Co(II) with a linear range covering from 1.0×10-7 to 5.0×10-5 M and a detection limit of 5×10-8 M. The experimental results show that the response behavior of the compound to Co(II) is pH independent in medium condition(pH 4.5-9.5) with excellent selectivity for Co(II) over transition metal cations except Cu(II). And the chemosensor has been used for determination of Co(II) in water samples.6. The synthesis of a new compound, amide-linked diporphyrin xanthene(ADPX), and its application for preparation of lead(II) ion selective electrodes are described. The electrode was prepared with a PVC membrane combining ADPX as an electroactive material, 2-nitrophenyl octyl ether (o-NPOE) as a plasticizer and sodium tetraphenylborate (NaTPB) as an additive in the percentage ratio of 3:3:65:32 (ADPX: NaTPB: o-NPOE: PVC, w:w). The electrode exhibited linear response with a near Nernstian slope of 28.2 mV per decade within the concentration range of 3.2×10-6 to 1.0×10-1 M lead ions, with a working pH range from 4.5 to 7.5, and a fast response time of less than 30s. Selectivity coefficients for Pb(II) relative to a number of interfering ions were investigated. The electrode is highly selective for Pb2+ ions over a large number of cations. Several electroactive materials and solvent mediators have been compared and the experimental conditions were optimized. The sensor was applied as indicator electrode in titration of Pb(II) with potassium chromate solution with satisfactory results.7. The synthesis of a new compound, amide-linked manganese diporphyrin xanthene(Mn2Cl2ADPX), and its application for preparation of thiocyanate selective electrodes are described. The electrode was prepared with a PVC membrane combining Mn2Cl2ADPX as an electro active material, 2-nitrophenyl octyl ether (o-NPOE) as a plasticizer in the percentage ratio of 3:65:32 (ADPX: o-NPOE: PVC, w:w). The electrode exhibited linear response within the concentration range of 2.4×10-6 to 1.0×10-1 M SCN-, with a working pH range from 3.0 to 8.0 and a fast response time of less than 60s. Several electro active materials and solvent mediators have been compared and the experimental conditions were optimized. Selectivity coefficients for SCN- relative to a number of interfering ions were investigated. The electrode exhibits anti-Hofmeister selectivity toward SCN- with respect to common co-existing anions. The electrode was applied to the determination of SCN- in body urine with satisfactory results.