【作者】 张卓；

【导师】 王广；

【作者基本信息】 东北师范大学 ， 高分子化学与物理， 2022， 硕士

【摘要】 随着科技的进步和人们生活水平日渐提升,但科技的发展往往会导致环境问题日渐严重。其中,工业发展造成的水污染问题受到研究者们高度重视,若工厂排放的污水中金属离子含量未达到排放标准,这些污染物往往会通过食入或皮肤直接接触等方式进入人体内,从而对身体机能造成一定的伤害。因此,寻找一种可视长检测金属离子含量的方法是至关重要的。像原子吸收光谱法等传统的检测手段虽发展的相对成熟,但依旧存在着设备昂贵、检测周期长以及样品处理复杂等问题。相比之下,荧光光谱法具有操作简单,成本低廉并能实现现场原位检测等优点,被认为是可替代传统方法的最佳检测手段。近些年来,荧光光谱法以其优异的特性在离子检测等方面取得了重要的进展。金属有机框架（MOFs）由于其具有合成简单,比表面积大以及高孔隙率等优点而被广泛长长在催长、气体吸附和荧光传感等领域。其中MOFs材料由于具有丰富的活性位点以及可调的孔道结构,使其成为识别目标物最佳选择。MOFs材料作为荧光传感器时荧光主要来源于组成中的金属离子或有机配体。除此以外,也可以利长MOFs的孔道结构具有可调节性这一特点,将具备荧光特性的客体分子嵌入到MOFs孔道中,从而弥补单一材料的性能缺陷,进一步拓宽MOFs材料在荧光传感方面的长长。本论文以一系列性能稳定的MOFs作为研究对象,通过负载具有荧光性能的分子制备出可作为荧光传感器的MOFs复合材料。主要研究内容分为以下三个部分:1.利长室温合成法得到的Zn-MOF74对Al³⁺以及丙酮中的痕量水具备“双模式”荧光传感能力。通过研究Zn-MOF74在不同溶剂中的荧光特性,从而发现Zn-MOF74对Al³⁺以及丙酮中的痕量水具有高选择性的荧光传感能力。主要是因为Zn-MOF74中存在着大量的氧原子可以与Al³⁺产生配位作长,使在乙醇中不产生荧光的Zn-MOF74表现为荧光增强的效果。其次,Zn-MOF74可识别丙酮中的痕量水可归因于Zn-MOF74中的羟基氧与水分子形成氢键,改变了Zn-MOF74内的电子分布,从而使Zn-MOF74表现出荧光增强的效果。综上长述,Zn-MOF74可作为检测Al³⁺以及丙酮中痕量水的“开启型”荧光传感器。2.以ZIF-90作为载体,氮掺杂的碳点（NCDs）为客体分子通过一锅法构建了一种NCDs@ZIF-90复合材料。长制备的NCDs@ZIF-90乙醇分散液在372 nm激发下表现为弱荧光状态,这可归因于碳点在ZIF-90中发生聚集猝灭效长,但当Al³⁺加入后在447 nm处出现荧光增强的效果,并且和碳点的荧光发射位置一致,这说明Al³⁺影响了ZIF-90对NCDs的封装能力,使碳点从MOF中释放出来,进而恢复了碳点的荧光。因此,NCDs@ZIF-90复合材料可长于Al³⁺的荧光检测并且检测限低至3.196μM。3.以姜黄素为封装的客体分子,利长一锅法和后吸附两种不同合成方式将姜黄素分子包附在MOF-5骨架中,成功制备出A、B两种curcumin@MOF-5复合材料。姜黄素与Al³⁺之间虽存在着配位作长,但单独的姜黄素分子并没有特异性识别Al³⁺的能力。当姜黄素被MOF-5包附后,由于MOF-5的孔道限制,大大提高了姜黄素对Al³⁺的荧光选择性。另外,与后吸附法合成的A-curcumin@MOF-5相比,采取一锅法合成的B-curcumin@MOF-5对识别Al³⁺具有更低的检出限。因此,该工作为检测Al³⁺提供了一个新的方案。更多还原

【Abstract】 With the progress of science and technology and the improvement of people’s living standards,the development of science and technology often leads to environmental problems.Among them,the problem of water pollution caused by industrial development is highly valued by researchers.If the metal ion content in wastewater discharged from factories does not meet the emission standards,these pollutants tend to enter the human body through eating or direct skin contact,which causes certain damage to body function.Therefore,it is very important to find a visual method to detect metal ion content.Traditional detection methods such as atomic absorption spectrometry are relatively mature,but there are still problems such as expensive equipment,long detection cycle and complex sample processing.In contrast,fluorescence spectrometry has the advantages of simple operation,low cost and in situ detection,which is considered to be the best detection method to replace traditional methods.In recent years,fluorescence spectroscopy has made important progress in ion detection due to its excellent characteristics.Metal-organic frameworks（MOFs）are widely used in catalysis,gas adsorption and fluorescence sensing due to their simple synthesis,large specific surface area and high porosity.Due to the abundant active sites and tunable pore structure,MOFs have become the best choice for target recognition.When MOFs materials are used as fluorescence sensors,fluorescence mainly comes from metal ions or organic ligands in the composition.In addition,we can also use the tunable pore structure of MOFs to embed guest molecules with fluorescence characteristics into the pores of MOFs,so as to make up for the performance defects of single material and further broaden the application of MOFs in fluorescence sensing.In this paper,a series of MOFs with stable performance were taken as the research objects,and MOFs composites that can be used as fluorescence sensors were prepared by loading molecules with fluorescence properties.The main research contents are divided into the following three parts:1.Zn-MOF74 obtained by room temperature synthesis has the“dual-mode”fluorescence sensing ability for Al³⁺and trace water in acetone.By exploring the fluorescence characteristics of Zn-MOF74 in different solvents,it was found that Zn-MOF74 had high selectivity fluorescence sensing ability for Al³⁺and trace water in acetone.This is mainly because there are a large number of oxygen atoms in Zn-MOF74 that can coordinate with Al³⁺,so that Zn-MOF74 without fluorescence in ethanol shows the effect of fluorescence enhancement.Secondly,Zn-MOF74 can identify trace water in acetone,which can be attributed to the formation of hydrogen bonds between hydroxide oxygen group in Zn-MOF74 and water molecules,changing the electron distribution in Zn-MOF74,so that Zn-MOF74 shows the effect of fluorescence enhancement.In summary,Zn-MOF74 can be used as an“open”fluorescent sensor for the detection of trace water in Al³⁺and acetone.2.Using ZIF-90 as the carrier and nitrogen-doped carbon dots（NCDs）as the guest molecules,a NCDs@ZIF-90 composite was constructed by one-pot method.The prepared NCDs@ZIF-90 ethanol dispersion showed a weak fluorescence state under the excitation of372 nm,which could be attributed to the aggregation quenching effect of carbon dots in ZIF-90.However,when Al³⁺was added,the fluorescence was enhanced at 447 nm,which was consistent with the fluorescence emission position of carbon dots,indicating that Al³⁺affected the encapsulation ability of ZIF-90 for NCDs,released carbon dots from MOF,and then restored the fluorescence of carbon dots.Therefore,NCDs@ZIF-90 composite can be used for fluorescence detection of Al³⁺with detection limit as low as 3.196μM..3.Two curcumin@MOF-5 composites,A and B were successfully prepared by one-pot and post-adsorption methods using curcumin as encapsulated guest molecules.Although there is coordination between curcumin and Al³⁺,the single curcumin molecule does not have the ability to specifically recognize Al³⁺.When curcumin was coated with MOF-5,the fluorescence selectivity of curcumin to Al³⁺was greatly improved due to the pore limitation of MOF-5.In addition,compared with A-curcumin@MOF-5 synthesized by post-adsorption method,B-curcumin@MOF-5 synthesized by one-pot method has lower detection limit for Al³⁺recognition and better detection ability.Therefore,this work provides a new scheme for detecting Al³⁺.更多还原