Anion Recognition And The Application Of Sensor For Phosphate Anion

Anion are ubiquitous throughout biological system. Anion play a fundamental role in a wide range of chemical and biological processes. Anionic guest species effect as environmental pollutants is now being realised. Corresponding specific receptors play roles in the areas of medicine and catalysis which attracted most interest. This has been especially true during the last 20 years. Numerous efforts have beeen devoted to the development of abiotic receptors for anionic species. Up to the present, numerous anion sensors have been devised, which bring in possibility and convenience for anion determination in biology system and environment. These work is very great applied value in catalysis, medicine, biology, environment and nutriology. The design of anion receptors is particularly challenge. There are a number of reasons for this. Anions are larger than isoelectronic cation and therefore have a lower charge to radius ratio. This means that electrostatic binding interactions are less effective than they would be for the smaller cation. Additionally anion may be sensitive to pH values (becoming protonated at low pH and so losing their negative charge), thus receptors must function within the pH window of their target anion. Anionic species have a wide range of geomeries and therefore a higher degree of design may be required to make receptors complementary to their anionic guest. Still, all kinds of including many capable of luminescence sensing were reported by far. However, the majority of receptors have concentrated on their behavior in nonaqueous solvents, rather few have the simplicity and accessibility which is ideally required for practical devices. At present, the selective recognition of anions in aqueous media by natural and synthetic receptor constitutes an important element of supramolecular chemistry. This is a more arduous task. Anions generally have large freeenergies of hydration besides above limitations. These bring difficulty for designing receptors in water media.During studying dinuclear ligands combining metal ions by colorimetry recognise phosphate, we found single Yb3+ can recognise phosphate by indicator titration in 10mM HEPES buffer at phosiological pH. The recognition system is more simpler, effective, selective. In our thesis, we investigated the recognition processe and mechanism, and obtained binding constants and thermodynamic parameters of the complexes by UV-Vis speactra and fluorescence. The significance of the work is that, applying simple system recognizes phosphate ion in water media which is one of important anions in lives, quantificationally detecting the concentration of phosphate in water by simple analysis method. We not only solved designing anion receptors in water but also broke through the routine which used synthetical organic receptors involving in a great deal of synthesizing work to recognize anions. Our system is more cheaper and convenient. Compared with those synthetic receptor and designed receptor, our system showed strong recognition to phosphate ions. On the base of conclusion, we applied the sysytem to determined the phosphate concentration from body fluid including urine and serum. In addition, we determined the phosphate concentration of milk from human and commerce milk. The ensemble should be hopefully acquired some application in clinic and commerce.The thesis is composed of following works:We used some synthesized simple ligands combining with metal ions by pyrocatechol violet, as the chromogenic indicator for the sensor to recognize the phosphate ions in water media: Kim et al have applied Zn2+ and Hbpmp by pyrocatechol violet as the chromogenic indicator to detection of phosphate in water at physiological pH. On the base of this, we have synthesized tripod dinuclear ligands containing phenoxo-bridging or pyridine at the top and imidazole, pyridine or pyrazole at the two arms. These logands may form metallic complexes via coordination by taking N or O atoms as electron donors. However, coordination is sometimes not saturated, phenol hydroxylof pyrocatechol violet will take part in coordinating as a complementarity. If there is more strong coordinative interactions between phosphate and metal ions, addition of phosphate to the solution of the ensemble produce a competition and the result is that pyrocatechol violet is released. Before and after of complexing, pyrocatechol violet will present changes both on UV-Vis spectra and color in the neutral water media. We studied the processes of system recognizing anions.During the investigation on dinuclear ligands, we discovered an even more simple and sensitive sensor for phosphate. The new ensemble is obtained by mixing YbCl3 and pyrocatechol violet in a 2:1 molar ratio in a 10mM HEPES buffer aqueous solution at pH 7.0. The sensor has a higher sensitivity and selectivity. The results indicated that (1) two Yb3+ ions combine with two phenol hydroxyl groups of pyrocatechol violet in neutral HEPES buffer. Addition the phosphate ions, phosphate snatch up the two Yb3+ which have combined with pyrocatechol violet. Pyrocatechol violet renews its character of dissociative state in neutral water media. Moreover, we validated the recognition mechanism by fluorescence. (2) the transition metal ions could not do the same jobs. Other lanthanide ions are incapable to work as well as Yb3+ does, although they can play the similar part. (3) NTPs and pyrophosphate anion bring about the similar variety with the sensor. As for ADP, the sensitivity is less than NTP's. One fact was sure, that is, cAMP,AMP and ppGpp were totally incapable of causing the change. More we deduced the recognition mechanism of our sensor.The phosphate concentration of urine and serum is strictly related with physiology and pathology. For instance, urolithiasis, prostatic disorders, hypoparathyroidism/hyperparathyroidism, osteoma, and rickets. The determination of free phosphate ion in human urine and serum is very important, since it has diagnostic value in some clinical cases. Now molybdenum blue assay for phosphate resorting to large apparatus is widespread in large-scale hospitals. However, these chemical methords have...