【作者】 王海霞；

【导师】 李希友；

【作者基本信息】 山东大学 ， 无机化学， 2010， 博士

【摘要】 近年来,在分子识别领域中荧光化学传感器以其高灵敏度、丰富的测量信号以及探头设计的简便而备受关注。因此,设计和合成新颖高效的荧光探针是化学工作者一项迫切任务。苝二酰亚胺类衍生物(PDIs)以其良好的光、热以及化学稳定性,同时化学可修饰性强等优点,迅速成为现代光、电材料领域中新型分子器件研究的热点。同时,PDI也是一种很好的电子受体,这种性质决定了以PDI为荧光团的光致电子转移(PET)型的荧光分了探针将会有很好的应用前景。在第一部分研究工作中,我们合成了两种不同的双皮考林胺为金属离子识别基团、PDI为荧光体的“关-开”型荧光探针PDI-1和PDI-2,通过氢谱、碳谱和质谱对分子结构进行表征,并对过渡金属离子的选择性进行实验。首先,PDI-1在各种不同的金属离子中,表现出对Ni2+高度的选择性,荧光增强达49倍；从ESI-MS、Job’s plot和荧光滴定曲线的非线性拟合等一系列实验结果确定PDI-l和Ni2+在DMF中形成化学计量比为1：2的配合物,通过Benesi-Hildebrand分析得出络合物稳定常数为2.7×109M-2,这是首次报导的表现出荧光增强的Ni2+荧光探针；PDI-2表现出对Fe3+良好的选择性,荧光增强达138倍,质谱结果显示PDI-2和Fe3+在DMF中形成1：2类型的稳定配合物。最有意义的结果是两个探针分子表现出的高选择性金属离子Ni2+和Fe3+都有强烈的顺磁性,是常见的荧光淬灭剂,因此发展Ni2+和Fe3+的荧光开型探针具有一定的挑战性,我们的研究结果表明在研究顺磁性金属离子荧光探针中,由于具有较高的氧化电位特点,PDIs是一种有利于荧光增强的荧光体。由于PDI结构可修饰性非常丰富,所以提出的作用机制对设计和发展其它新型的荧光探针很有价值。4-胺基-1,8-萘酰亚胺衍生物和PDIs类似也是一种良好的荧光染料。由于其荧光量子产率高、荧光发射波长适中、斯托克斯(stocks)位移大等优点,在工业荧光染色、激光材料、光电转换材料、荧光标记和荧光探针等方面都得到了广泛应用,尤其是光稳定性强、结构简单以及易于修饰等优点,成为荧光探针研究中一类重要的荧光团。在第二部分研究工作中,我们以分子内电荷转移(ICT)为工作机制,4-溴-1,8-萘酐为原料合成了两种结构新颖的萘酰亚胺类荧光探针NaI-1和NaI-2,在8：2乙腈和水(V:V)混合体系中,都表现出对铜离子(Ⅱ)优良的选择性和灵敏性,竞争实验表明其它金属离子的干扰非常小；在铜离了滴定过程中,吸收光谱中的最大吸收峰蓝移近80nm,job’s plot结果清楚地表明NaI-1和NaI-2两种探针分子和Cu2+形成的配合物的化学计量比分别为1：1和1：2,晶体结构清楚表明NaI-1和铜离子(Ⅱ)形成稳定五配位的化合物,通过Benesi-Hildebrand分析得出形成配合物的稳定常数分别为4.5×104M-1和3.12×109M-2,稳定性相当；同时,随着铜离子浓度的增加,其荧光几乎完全淬灭。在B3LYP/6-31G*水平上对NaI-1和NaI-1／Cu2+配合物进行DFT计算,结果表明NaI-1和Cu2+形成的配合物吸收光谱最大值和NaI-1相比明显蓝移,该结果和实验结果非常一致；同时做出主要贡献的前线分子轨道的电荷分布表明萘酰亚胺配体到金属铜的电荷转移是导致荧光淬灭的主要原因。在第三部分研究工作中,我们合成了以4-胺基-萘酰亚胺为荧光体、两种结构不同的皮考林胺(DPA)为离子识别基团的化合物NaI-3,通过’H NMR.13CNMR和ESI MS对分子结构进行表征。在纯乙腈中,分别加入Zn2+和Cu2+,吸收光谱最大值分别蓝移50 nm和80 nm,但是荧光性质截然不同,加入Zn2+荧光量子产率增大6.6倍,这主要是由于位于亚酰胺位置的四齿配体和锌离子络合后PET过程受阻导致荧光恢复；加入Cu2+后,由于ICT效应减弱,荧光量子产率进一步降低；加入等摩尔数的Zn2+、Cu2+时,荧光量了产率变化微弱。在传感性能基础上,利用PET和ICT两种因素,在单分子水平上实现了双化学信号输入／单荧光信号输出的逻辑操作-INHIBIT逻辑门,为高级复杂的逻辑门分子设计和发展提供了有益可靠的实验依据。更多还原

【Abstract】 Fluorescent probes for sensing and monitoring chemical analytes are a topical and attractive field for chemistry, biology and environmental science due to their high sensitivity and simplicity. Developing highly effective fluorescent probes is thus a fundamental task for organic and analytical chemists.Perylene tetracarboxylic diimides (PDIs) are attractive molecular building blocks that are currently being extensively investigated for use in a variety of photoactive organic materials, such as organic field-effect transistor (OFET), light-harvesting solar cells, light emitting diodes. These dyes have recently generated great interest in the field of photonic materials, because of their excellent thermal and photo stability, high luminescence efficiency, easy modification on the molecular structure,, and desirable optical and redox characteristics. PDIs are good electron acceptors with low reduction potential. Therefore PDIs are promising candidates for the application as fluorophores in fluorescent probes based on photoinduced electron transfer (PET).In the first part of our research, two novel "turn-on" fluorescent probes with PDI as the fluorophore and two different di-(2-picolyl)-amine (DPA) groups as the metal ion receptor (PDI-1 and PDI-2) were successfully synthesized with satisfactory yields. PDI-1 exhibited high selectivity toward Ni2+ in the presence of various other metal cations including Zn2+, Cd2+ and Cu2+ which were expected to interfere significantly. A 1:2 stoichiometry was found for the complex formed by PDI-1 and Ni2+ by a Job’s plot and by non-linear least square fitting of the fluorescence titration curves. The binding constant Ka was determined to be 2.7×109 M-2 through the Benesi-Hildebrand analysis. By introducing an extra diamino ethylene group between DPA and the phenyl bridge, the receptor was modified and the high selectivity of the PDI-based fluorescent chemosensor shifted to Fe3+ from Ni2+. The enhancement factor of fluorescence response of PDI-2 to Fe3+was as high as 138. The results of ESI MS showed that the stoichiometry of the complex between PDI-2 and Fe3+ in N, N-dimethylformamide (DMF) was 1:2. The binding behavior of the receptors in these two compounds is affected significantly by the PDI fluorophores. Most interestingly, both Ni2+ and Fe3+ are paramagnetic metal ions, which are known as fluorescence quenchers and are rarely targeted with turn-on fluorescence probes. This result suggests that PDTs are favorable fluorophores for a "turn-on" fluorescence probe for paramagnetic transition metal ions because of the high oxidation potential.4-amino-1,8-naphthalimide derivatives are also excellent fluorescence dyes like PDIs. Due to their remarkable luminiscent properties, they have found increasing applications in a number of areas including colouration of polymers, fluorescent solar energy collectors, liquid-crystal additives, electro-optically sensitive materials, fluorescent markers in medicine and biology and ion probes. Especially, they absorb and emit in the visible range with large Stokes’shift, high fluorescence quantum yield, and they have the advantages of high photostability, simple structure and easy approaches to modification, which are favorable properties for the design of fluorescent chemosensors.In the second part of our research, based on the strategy of intramolecuar charge transfer (ICT) two novel fluorescent probes using 4-amino-1,8-naphthalimide as fluorophore and dipicolylamine as receptor for metal cations were successfully synthesized and characterized through 1H NMR,13C NMR, ESI-MS and MALDITOF-MS. Both of them showed high selectivity towards Cu2+ in acetonitrile-aqueous (8:2) mixture at room temperature. Addition of Cu2+ to Nal-1 or NaI-2, a 80 nm blue shift of the absorption maximum produced because of complexation between probes and copper ions, which resulted in the reduced ICT effect. The fluorescence of fluorophore was almost quenched in stark contrast to other metal ions. The results of DFT calculation based on B3LYP/6-31G* level indicated the charge transfer from the excited naphthalimide moiety to Cu2+ center was responsible for the remarkable fluorescence quench. Via Job’s plots and non-linear least square fitting of the absorption titration curves,1:1 and 1:2 stoichiometry were found for the complex formed by Nal-1 and Cu2+, Nal-l and Cu2+, respectively. The binding constant Ka and Ka’ were determined to be 4.5×104 M-1 and 3.12×109 M-2, respectively through Benesi-Hildebrand analysis. Based on the results of part 2, new compound N-p-(N’-2-(N",N"-di(2-pyridylmethyl) amino-ethylene) aniline)-4-N"’-di (2-pyridylmethyl) amino-1,8-naphthalimide (NaI-3) was successfully synthesized and characterized through ’H NMR,13C NMR and ESI MS. Addition of Zn2+ to NaI-3 in acetonitrile produced a 50 nm blue shift of absorption maximum, while the fluorescence quantum yieldΦduring the titration of zinc ions was remarkablely increased from 0.09 to 0.60. Both of them attributed to the formation of a NaI-3/Zn2+ complex, which resulted in a decreasing ICT effect and the inhibited PET process. On the other hand, addition of Cu2+ to NaI-3 in acetonitrile produced an 80 nm hypsochromic shift of absorption maximum, while the fluorescence quantum yieldΦwas dramastically decreased from 0.09 to 0.01, which was caused by the reduced ICT effect and ligand to metal charge transfer (LMCT) process, respectively. While addition of the equal equivalence of Cu2+ to the NaI-3/Zn2+ complex system, the quantum yield of fluorescence decreased from 0.6 to 0.2. Compound NaI-3 described here could be considered to perform an integrated circuit function with one AND and one NOT, which could be interpreted by a two-input INHIBIT logic gate. The present results demonstrated an efficient way for elaborating and transmitting information at a single molecular level and will be useful for further molecular design to mimic the function of the complex logic gates.更多还原