【作者】 阴彩霞；

【导师】 杨频；

【作者基本信息】 山西大学 ， 无机化学， 2005， 博士

【摘要】 阴离子在生物体系中无处不在,在广泛的生化过程中扮演着重要的角色,阴离子在环境污染方面的效应现在也被人们意识到。相应的人工阴离子受体,由于其在医学、催化学和环境学等有潜在的价值,已经引起人们很大的兴趣,在近20年内,这个发展尤其明显。人们投入巨大的努力去发展阴离子物种的非生物受体,进而设计出了阴离子的各种各样的传感器。这样,给阴离子在生物体系和环境中的测定提供了很大的可能性和方便性,这在催化学、医学、生物学、环境学、营养学等领域有很大的实用价值。阴离子受体的设计是具有相当挑战性的,这是因为:阴离子比等电子阳离子大,因此有一个较低的电荷对的半径比,这意味着他们相对较小的阳离子,静电键合作用是非常小的;另外阴离子对pH值是敏感的（在低pH值时变得去质子化将会失去它们的负电荷）,这样受体必须在目标阴离子的有效的pH范围内发挥功能;再者阴离子物种有很广泛的几何结构,因此需要较高程度的设计去使得受体满足它们的阴离子客体。尽管如此,到目前为止,各种各样包括许多能发光识别的阴离子受体被报道,然而,由于其识别介质是有机相,所以其中只有相当少的一部分是简单并能在实践中获得理想的应用。目前通过自然的和合成的受体在水溶液中选择性识别阴离子构成了超分子化学的重要部分。但这更是一个艰巨的任务,因为阴离子除了有以上局限性外,还有很大的水合自由能,这必定给设计一定离子的水介质中的受体带来一定的困难。 本文在研究阴离子识别的过程中,发现了两种双核配体可以与金属结合,利用邻苯二酚紫显色在水介质中识别磷酸根。更可喜的是:我们发现了单独使用镧系离子Yb³⁺,通过邻苯二酚紫的显色反应,在pH=7.0、10mM的HEPES的生理环境中可以识别磷酸根,体系简单、效果明显、选择性好。本文通过紫外可见光谱和荧光光谱对识别的过程和机理做了探讨,并得出了识别体系的键合常数和热力学常数。本课题的意义在于,使用简单的体系,在水介质中识别生物体系中重要的阴离子之一—磷酸更多还原

【Abstract】 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更多还原