Bifunctional Photoacids with Multicolour Emission

激发态质子转移（ESPT）反应是荧光光谱和光化学的独特结合。基于这种系统的内在双重发射，我们最近开发了一种底物，它显示了四种发射颜色，依赖于两种不同酶的两个正交切割位点。虽然酶促转化代表了现实条件下的不可逆转化，但我们希望将由不同发射颜色编码的正交反应性的这一有前途的概念转移到可逆反应中，并将其与非正交结合位点的行为进行比较。后者的系统是由光酸的网站，结合一个光碱性moiet.Thermodynamics和动力学可逆键的形成和解离的NMR光谱和荧光相关光谱，分别探测。这些测量允许量化一个位点上的结合影响另一个位点处的结合的程度。路易斯碱与硼取代的羟基芘衍生物的可逆结合预期充当正交结合位点。羧基化羟基芘衍生物在一个分子内结合了联合收割机的光酸性和光碱性。作为光碱的公认羧酸盐由亚胺碱补充;后者化合物最近被描述为所谓的超级光碱的一部分。由于预期酸性的顺序在激发时会改变，因此可以探测通过氢键网络从羟基部分到碱性位点的ESPT。计划在研究各种溶剂组合物中的氢键链时利用这一特征。因此，该资助提案的一个主要目标是制备适合各种光谱学方法需要的量和溶解度的各种区域异构体。

The unique combination of fluorescence spectroscopy and photochemistry is found in the excited-state proton transfer (ESPT) reaction. Based on the intrinsic dual emission of suchlike systems, we recently developed a substrate which shows up to four emission colors in dependence of two orthogonal cleavage sites for two different enzymes. While the enzymatic conversions represent irreversible transformations under realistic conditions, we would like to transfer this promising concept of orthogonal reactivities, encoded by different emission colors, to reversible reactions and would like to compare it to the behavior of non-orthogonal binding sites. The latter system is represented by the photoacidic site, combined with a photobasic moiety.Thermodynamics and kinetics of reversible bond formation and dissociation are probed by NMR-spectroscopy and fluorescence correlation spectroscopy, respectively. These measurements allow for quantifying the extent by which binding on one site influence the binding at the other site. The reversible binding of Lewis-bases to Boron-substituted hydroxypyrene derivatives is expected to act as the orthogonal binding sites. The carboxylated hydroxypyrene derivatives combine photoacidity and -basicity within one molecule. The well-established carboxylate as photobase is complemented by an imine base; this latter compound was recently described as part of a so-called super-photobase. As the ordering of acidities is expected to change upon excitation, ESPT from the hydroxyl-moiety to the basic site via a hydrogen-bonding network can be probed. It is planned to exploit this feature in studying hydrogen-bonding chains in various solvent compositions. Therefore, one major objective of this grant proposal is the preparation of various regioisomers in amounts and solubility which fit to the needs of the various spectroscopy methods.