【作者】 胡育林；

【导师】 苏致兴；

【作者基本信息】 兰州大学 ， 高分子化学与物理， 2009， 博士

【摘要】 近年来,控制环境污染已成为工业生产中一个引人注目的问题,也吸引众多研究者的关注。由于荧光检测技术敏感度高,选择性好且具有多功能等优点而广为人知。因此合成对金属离子具有识别能力的荧光小分子至关重要。但荧光小分子在应用中容易脱落,同时与基材相溶性不好,仪器稳定性受到影响。相比之下,高分子材料具有很好的稳定性和成膜性,易于制成各种器件;并且,与溶液检测技术相比,膜检测具有可多次重复使用,易保存,操作简便、处理效率高等优点。在综述部分,我们对近年来报道的对金属离子具有识别能力的荧光小分子探针及光诱导电子转移（PET）和分子内电荷转移（ICT）两种识别机理进行了归纳介绍,并介绍了其在高分子材料方向的发展情况。由于铁离子在新陈代谢过程和生物材料中所起的重要作用,发展对铁离子具有高选择性和敏感性的传感材料成为一个重要的科技项目。本论文结合荧光小分子的离子识别能力和高分子材料优良的成膜性,采用荧光小分子高分子化的方法来制备对Fe³⁺具有选择识别的高分子材料,再利用高分子膜的成膜性制备可对Fe³⁺选择识别的高分子膜材料。本文分别选用诺氟沙星和1,8-萘酰亚胺小分子作为原料,采用不同方法制备得到对Fe³⁺具有较好选择性的荧光高分子材料。我们对所得到的小分子的光物理性质进行了研究,并探讨了高分子材料在溶液和膜状态下的离子识别范围,线性关系,响应时间等性质。研究取得如下成果:（1）以诺氟沙星为荧光小分子,合成可聚合的单体分子,与甲基丙烯酸甲酯（MMA）聚合之后得到侧链含诺氟沙星单元的发蓝光聚甲基丙烯酸甲酯（PMMA）高分子。对侧链含有一种诺氟沙星单元衍生物的PMMA高分子和侧链含有两种诺氟沙星单元衍生物的PMMA高分子,分别研究了其溶液和固体的基本发光性能、高分子溶液的溶剂化效应及离子效应。发蓝光的高分子材料在溶液中由于过渡态金属离子与发色团的配位加速了分子内部电荷转移（ICT）过程,因此金属离子对高分子溶液的荧光均有部分猝灭效应。由于Fe³⁺氧化性较强,表现的荧光猝灭现象更为突出,其他金属离子由于高分子链的卷曲对小分子的保护使得荧光影响微弱。并且Fe³⁺的猝灭机理符合Stem-Volmer动力学关系。（2）分别采用两种路线合成了以萘酰亚胺衍生物为荧光小分子,并制得发绿色荧光的高分子材料。第一种方法是先合成荧光小分子单体,后与MMA共聚的方法得到发绿光的油溶性高分子PMMA材料。合成得到的小分子发绿色荧光,具有很强的溶剂化作用,在非极性有机溶剂中具有较高的荧光量子产率。我们对过渡态金属离子对荧光高分子材料在有机溶液及膜状态下的基本荧光性质的影响作了详细的研究。当Fe³⁺在不同的浓度区间,溶液和膜的相对荧光强度（F₀/F）与[Fe³⁺]均能满足一定的线性关系。第二种方法是采用先聚合再悬挂得到水溶性的发绿光的聚丙烯酰胺（PAM）高分子材料。研究了pH值对其水溶液荧光的影响,根据其非线性变化曲线计算得到荧光小分子的酸性常数pKa为3.5。该水溶性荧光高分子在水溶液中对Fe³⁺和Cu²⁺均表现很好的配位能力。（3）对含有两种具有光谱重叠（一种小分子的发射光谱与另一小分子的激发光谱发生较大程度的重叠）的荧光小分子的高分子材料进行了研究,探讨了高分子膜中的两种小分子的分子间能量转移现象及金属离子等对高分子材料发光性能的影响。首先是侧链含有诺氟沙星和二胺基吖啶的水溶性PAM高分子材料。该材料在溶液中表现的是两种小分子分别的荧光性质,能量转移现象不明显。在膜及粉末状态时,由于小分子间距离减小,发生了明显的能量转移过程;且当能量受体分子含量较高时,能量转移效率较大。被测金属离子中Fe³⁺表现出明显的荧光猝灭现象。在水溶液中,金属离子Fe³⁺对诺氟沙星发色团的猝灭效应要强于对胺基吖啶发色团的猝灭。在乙醇环境中,过渡金属离子对高分子膜两处荧光强度的猝灭作用则表现一致。总之,两处发射峰的荧光强度与金属离子浓度之间形成的线性关系能够提高检测的准确性。其次是制备两种具有光谱重叠的萘酰亚胺衍生物分子,分散在油溶性材料聚氯乙烯（PVC）中得到PVC荧光膜。改变两种分子的比例,发现能量受体分子含量越高,从能量给体向能量受体分子转移的能量越多,既较高处荧光强度与较低处荧光强度值比值越大。而pH环境对PVC荧光膜的影响很小。对于所研究的过渡态金属离子,只有Fe³⁺对此PVC荧光膜表现持续的荧光猝灭作用。并且当Fe³⁺在不同的浓度区间,PVC膜两处发射峰的相对荧光强度（F₀/F）与[Fe³⁺]均满足一定的线性关系。论文合成的几种新型荧光高分子材料均对Fe³⁺具有较好的选择性,并且荧光强度与离子浓度之间满足一定的线性关系。该项研究为荧光高分子用于Fe³⁺的检测提供了理论指导,并为制备相应的传感材料和器件奠定了基础。更多还原

【Abstract】 In recent years,the environmental pollution has been a major concern of the present industrial societies.Fluorescence-based sensors are well known for their high sensitivity,versatility,and fairly good selectivity compared to absorption sensors. Thus the development of new functional fluorescent compounds having responsibility to metal ions is important for expanding the utilization of fluorescent chemosensors. But,any supersaturated concentration of dye is likely to result in migration and phase separation in application.Polymer materials have good stability and high quality of film making.Compared with the detection technique in solution,detecting in film state have showed much more advantages such as the reproductivity,being easy to preserve,the simplified operation and being effective.In the first department of this paper,the latest research progress in supramolecular fluorescence sensors and switches used for metal cation recognition is summarized.Two types of systems were reviewed,photo-induced electron transfer（PET） and intramolecular charge transfer（ICT） systems.And the development of fluorescent polymeric sensor for metal cation recognition was reviewed.Since iron plays an important role in metabolic processes and biological materials,the development of highly selective and sensitive sensors able to detect iron cations in the soil and water sources has become a very important scientific goal. Integrating together the recognition capability of the dyes and the advantages of polymeric materials,the fluorescent polymers having the ability to recognizing metal cation Fe³⁺ were obtained based on norfloxain and 1,8-naphthalimide.The photophysical properties of fluorescent compounds synthesized in this paper were detected,and properties of the fluorescent polymer in the area of reorganization range of metal ions,relationship between fluorescent intensity and concentration of ions and response time were measured in the solution and film state.（1） Novel norfloxacin-containing fluorescent polymers were synthesized via copolymerization of one or two kinds of derivatives of norfloxacin and methylmetacrylate（MMA）.Fluorescence characteristics of the polymers as a function of pH and metal cations were investigated in aqueous solution and film state.The presence of metal cations(Mn²⁺,Fe³⁺,Co²⁺,Ni²⁺,Cu²⁺ and Zn²⁺) could quench the fluorescence intensity of the polymers in different levels because the coordination of metal ions and the dyes accelerated the ICT process.Exhibiting powerful oxidizing properties,Fe³⁺ showed the strongest fluorescent quenching on the fluorophores, which was accordance with Stem-Volmer dynamics.The results suggested the possibility that this newly synthesized compound works as a polymeric sensor responding to water polluted by protons and Fe³⁺.（2） Novel naphthalimide-containing green fluorescent polymers were synthesized via two methods.Firstly,we obtained green fluorescent polymers PMMA throught the copolymerization of the monomeric derivative of 1,8-naphthalimide and MMA.The monomeric derivative of 1,8-naphthalimide is a solvatochromic fluorophore exhibiting strong fluorescence in nonpolar solvent.The responses of the polymer in solution and in film state to metal cations were detected in detail.Different linear relationship were received between the relative fluorescent intensity（F₀/F） and the concentration of Fe³⁺[Fe³⁺]in the different range of[Fe³⁺].Then a novel water-soluble green fluorescent polymer PAM was synthesized based on 1,8-naphthalimide through a series of easy reactions with high yields. Fluorescence characteristics of the polymer as a function of pH were investigated, with the pK_a 3.5.The presence of metal cations(Cu²⁺and Fe³⁺) could quench efficiently the fluorescence intensity of aqueous solution of this polymer.（3） The fluorescent polymer containing two dyes having spectra overlap （emission spectrum of the donor partially overlaps the absorption spectrum of the acceptor） were prepared.The photophysical characteristics of the polymer such as the energy transfer phenomenon between the two dyes and the response to metal ions were detected.A new kind of bichromophoric Poly（acrylamide） covalently linked with norfloxacin（NF） and proflavine（PF） molecules were synthesized with different contents of the two dyes.The photophysical properties of the polymer were investigated that energy transfer（ET） from norfloxacin to proflavine occurred in the solid state（containing film and powder） of the polymer but not in aqueous solution because of the high concentration of chromophore groups existing in solid state（film and powder state）.The transfer efficiency increased linearly with the content of acceptor either in film or in powder state.Responses of different metal caions on the fluorescence intensity of the polymer solution were investigated.Only Fe³⁺ ions exhibited remarkable fluorescence intensity quenching to the polymer.The linear relationship between[Fe³⁺]and fluorescence intensity can be recorded synchronously at two position,which could enhance the selectivity and precision of the sensor both in aqueous solution and in film state.Fluorescent polyvinyl chloride（PVC） films were prepared thought doping two 1,8-naphthalimide derivates（having spectra overlap） into PVC.The energy transfer efficiency increased linearly with the content of acceptor,pH environments have no influence on the fluorescence of the film.Response of different metal caions on the fluorescence intensity of the film was investigated.Only Fe³⁺ ions exhibited remarkable fluorescence intensity quenching.Different linear relationship were received between the relative fluorescent intensity（F₀/F） at two emission wavelength and the concentration of Fe³⁺ in the different range of[Fe³⁺].All the newly synthesized materials showed selectivity to Fe³⁺,and linear relationship between the fluorescent intensity and the concentration of Fe³⁺ were obtained.They may be as potential efficient and selective sensors for water pollution by Fe³⁺ cations.更多还原