【作者】 徐美芸；

【导师】 吴水珠；

【作者基本信息】 华南理工大学 ， 材料学， 2010， 博士

【摘要】 本工作根据荧光共振能量转移(FRET)原理,选定了丹磺酰基(DNS),7-硝基-2,1,3-苯并氧杂噁二唑(NBD),异硫氰酸荧光素(FITC)为能量供体,罗丹明B为能量受体,通过环糊精的定位作用将两者绑定在FRET的有效距离内,使给体与受体间发生高效率的能量转移；此外,根据软酸硬碱理论(SHAB),我们改变配体中与金属离子络合部分的化学组成,从而使这些超分子体系表现出对特定离子的选择性识别功能,为其在离子检测等方面的应用提供新的途径。本论文的主要内容和结果如下：将单氨基β-环糊精与丹磺酰氯反应生成单(6-丹磺酰基-6-脱氧)-β-环糊精,以此作为主体分子；罗丹明B与二乙基三胺反应后与由N-羟基琥珀酰亚胺(NHS)活化的金刚烷甲酸反应,生成客体分子AD-SRhB。将客体分子与主体分子在水溶液通过金刚烷与环糊精的疏水相互作用形成β-CD-DNS/AD-SRhB超分子体系,使能量受体和供体之间的距离保持在可有效实现FRET的距离之内。通过对AD-SRhB／β-CD-DNS体系的光谱学性质研究,证实此体系在Fe3+存在时,内酰胺罗丹明会发生开环反应,从而形成与供体生色团能级匹配的罗丹明B开环结构作为能量受体,因此供体(连在β-环糊精上的丹磺酰基)的激发态能量转移给受体(罗丹明B／Fe3+络合物),由此实现了FRET,也实现了在水溶液中对Fe3+的荧光比率检测。按照软酸硬碱理论(SHAB),我们改变了配体中与金属离子络合部分的化学组成,由原来的亚胺基变为脲基,使配体中与金属离子结合部分“变软”,合成制备了含脲基配体的环糊精主体,以及含荧光素供体的客体分子,并制得了HOST1／GUEST 3包合物体系。此体系仍然是对三价铁离子的响应最明显,但体系同时对软酸金属离子二价汞离子也表现出了一定的响应性。在HOST 1/GUEST 3体系中,由于我们将供体生色团引入了疏水的环糊精内腔中,供体生色团的荧光量子产率得到了提高。同时我们还合成了带有DNS,NBD的金刚烷作为客体GUEST 1和GUEST 2,与HOST 1形成超分子体系HOST 1/GUEST 1和在HOST 1/GUEST 2.对三种供体生色团的对比研究可见,DNS-ADA引入环糊精的疏水微腔后,其荧光发射峰位置出现明显蓝移,导致其与受体生色团的能级不匹配,因此无法形成有效的FRET体系；而NBD作为供体时,由于其具有强吸电性,致使体系的能量转移有限。三种供体生色团中,FITC-ADA能与含配体的环糊精形成较好的FRET体系。为了实现对Hg2+的检测,我们在罗丹明配体生色团中引入软碱性更高的硫脲基,制备了含硫脲罗丹明配体的环糊精HOST 2,利用其与供体生色团GUEST 3的疏水相互作用制得了HOST 2/GUEST 3包合物体系。考察了HOST 2/GUEST 3包合物体系的光谱学性质,结果表明硫脲基的引入提高了配体生色团的碱软度,使得包合物体系对软酸金属离子汞离子具有很好的亲合力,可以选择性地与汞离子络合,因此该体系可用于汞离子的选择性荧光比率检测。在HOST 2/GUEST 3包合物体系中,当加入汞离子时,罗丹明配体可充分开环形成受体,由此供体生色团和受体生色团之间可以发生高效的能量转移。我们还尝试将HOST 2/GUEST 3包合物体系用于自来水和一些生理液体如尿液及血清中的汞离子荧光比率检测,结果表明,我们获得了一种在水相中对汞离子具有选择性识别检测功能的新型荧光传感器,并可应用于环境和生物检测。更多还原

【Abstract】 In this thesis, according to the principles of Fluorescence Resonance Energy Transfer (FRET), we chose dansyl (DNS),7-nitrobenzofurazan (NBD), FITC as the donors, rhodamine B as the acceptor. Due to its unique structural feature, cyclodextrin can keep the donor and acceptor within the effective distance of the Forster energy transfer. Based on the Hard Soft Acid Base (HSAB) principle, we changed the chemical structure of the metal-ion ligand, so that the supramolecular-complex exhibited specific ion selective recognition. These supramolecular complexs may find new applications in ion detection. The main contents and the results of this work are as follows:First, we synthesized mono-6-deoxy-6-dansyl-β-CD through the reaction of mono-6-deoxy-6-amino-β-CD with dansyl chloride; then, the guest AD-SRhB was synthesized by the process in which Rhodamine B was reacted with diethylenetriamine first, and then reacted with the activated 1-adamantanecarboxylic acid. The supramolecular-complex AD-SRhB/β-CD-DNS was prepared. Spectral analysis of AD-SRhB/β-CD-DNS supramolecular-complex confirms that the addition of Fe3+ can promote the formation of the open-ring state of the SRhB moieties and the excited energy of donor (linked on cyclodextrin rim) could be transfered to the acceptor(rhodamine B/Fe3+). The antidisturbance experiment shows that in the presence of multifarious cations, the AD-SRhB/β-CD-DNS supramolecular-complex has very good antidisturbance. In this system, efficient energy transfer can occurr between pH 4-7. Therefore, this FRET-based supramolecular sensor can be readily formed via an inclusion process using the donor part and the acceptor part, and can serve as a water-soluble ratiometric fluorescent sensor for Fe3+.According to the mechanism of Hard Soft Acid Base (HSAB), we changed the chemical structure of the ion-ligand to carbamido from imino in order to improve the softness of the "soft base". Therefore, we synthesized the host(HOST 1) with carbamido group and the guest(GUEST 3) with fluorescein moiety to form the supramolecular-complex HOST 1/GUEST 3. This supramolecular-complex showed good response toward Fe3+, as well as a certain response to Hg2+ in aqueous medium. In the HOST 1/GUEST 3 supramolecular-complex, the donor was within the hydrophobic cavity of cyclodextrin, so the fluorescence quantum yield of donor was improved. The antidisturbance experiment shows that in the present of multifarious cations including Hg2+, the HOST 1/GUEST 3 supramolecular-complex has quite good antidisturbance. Moreover, DNS-ADA and NBD-ADA were also synthesized as the donors. But we found that when DNS-ADA enters the hydrophobic cavity of cyclodextrin, the emission profile of DNS exhibited hypsochromic shifts markedly. It results in the energy level mismatch of DNS and the acceptor, hence the FRET of supramolecular-complex HOST 1/DNS-ADA can’t occur. When the NBD-ADA was used as the donor, because of its strongly electron-withdrawing feature, the efficiency of energy transfer of supramolecular-complex HOST 1/NBD-ADA was limited. Therefore, FITC-ADA is the better donor for rhodamine B/Fe3+ complex for the FRET system.For detecting Hg2+, we further improved the "soft base" of the ligand by changing the chemical structure of ligand from carbamido group to thioureido group. Cyclodextrin with thioureido moiety was synthesized as HOST 2, and the FITC-ADA as the GUEST 3. The supramolecular-complex HOST 2/GUEST 3 was formed in aqueous solution. Spectral analysis of HOST 2/GUEST 3 supramolecular-complex confirms that thioureido moiety can improve the "soft base" of the ligand evidently and the ligand could complex with Hg2+ selectively. This strategy provides a water-soluble ratiometric fluorescent sensor for Hg2+. In the HOST 2/GUEST 3 supramolecular-complex, the addition of Hg2+ can promote the formation of the open-ring state of the SRhB moieties and the excited energy of donor (in cyclodextrin) could be transfered to the acceptor (rhodamine B/Hg2+ complex linked on cyclodextrin). The efficiency of energy transfer of the supramolecular-complex HOST 2/GUEST 3 reaches 90.2%.HOST 1/GUEST 3 supramolecular-complex has the very good antidisturbance. Its application in the environment and biological detection was investigated, for instance, Hg2+ detecting in tap water, in serum and urine. In summary, the supramolecular-complex HOST 2/GUEST 3 can serve as a water-soluble ratiometric fluorescent sensor for Hg2+, and can be used in environment and biological detection.更多还原