Development of molecular photoswitches for the effective control of the pH value of aqueous solutions by visible light

开发可见光有效控制水溶液pH值的分子光电开关

• 批准号: 279617770
• 负责人: Dr. Benjamin Koeppe
• 金额: --
• 依托单位: Arbeitsgruppe Organische Chemie und funktionale Materialien
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/279617770?language=en
• 关键词: Development; molecular; photoswitches; effective; control

The aim of this project is the development of certain chemical compounds, hereafter called pH photoswitches, whose aqueous solutions experience a variation in pH values upon irradiation by visible light in such a way that an initial variation can be reversed by a change in the color of the light. Controlling the pH through irradiation by light, which can be performed in high spatial as well as time resolution, offers several potential applications in research and technology, as many biological and technical processes are pH dependant and may thus, using such pH photoswitches, be controlled indirectly by irradiation even if primarily not light sensitive. All the substances for the purpose of reversible pH modulation so far available, however, have strong limitations and none of them have found broad application. Typical limitations, to be overcome in the course of this project, are meager changes in pH or short time durations of such changes and the necessity to use UV light. Among the well known photochromes, indigoid dyes, especially thioindigo derivatives, seem to be best suited for the development of novel pH photoswitches. Thioindigo derivatives exist in two geometrical configurations (trans und cis isomers) which may be interconverted by irradiation by visible light while the concurrent spontaneous conversion to the trans isomer takes place with a half life of a few hours. The change in configuration may be exploited in the control over the formation of intramolecular hydrogen bonds (H bonds) between acidic or basic groups within the molecule. Such H bonds modulate the acidity of the molecule as a whole and may eventually change the pH of the surrounding solution by a few units. One major challenge in the realization of this concept lies in the design of molecular structures that allow for the formation of hydrogen of maximum strength and to thus maximize the variation in acidity. Another challenge is to ensure good solubility of the dyes in water. Following the chemical synthesis of the novel compounds which is expected to be feasible using well established techniques, and after the UV/Vis spectroscopic determination of parameters of photo chemistry and acid base chemistry, characterization of the hydrogen bonds, primarily by NMR spectroscopy, will be of major importance in the structure optimization of pH photoswitches.

该项目的目的是开发某些化合物，以下称为pH光电开关，其水溶液在可见光照射下经历pH值的变化，这种变化可以通过光的颜色变化来逆转。通过光照射来控制pH，这可以在高空间和时间分辨率下进行，在研究和技术中提供了几种潜在的应用，因为许多生物和技术过程是pH依赖性的，因此，使用这种pH光电开关，可以通过照射间接控制，即使主要不是光敏的。然而，迄今为止可获得的用于可逆pH调节目的的所有物质都具有很强的局限性，并且它们中没有一种具有广泛的应用。在本项目过程中要克服的典型限制是pH值的微小变化或这种变化的持续时间短以及必须使用紫外线。在众所周知的光致变色剂中，靛蓝染料，特别是硫靛衍生物，似乎最适合于开发新型pH光开关。硫靛衍生物以两种几何构型（反式和顺式异构体）存在，其可以通过可见光照射而相互转化，同时自发转化为反式异构体，半衰期为几小时。构型的变化可用于控制分子内酸性或碱性基团之间的分子内氢键（H键）的形成。这样的H键调节整个分子的酸度，最终可能会改变周围溶液的pH值几个单位。实现这一概念的一个主要挑战在于设计分子结构，以允许形成最大强度的氢，从而使酸度的变化最大化。另一个挑战是确保染料在水中的良好溶解性。在使用成熟的技术进行新型化合物的化学合成（预计是可行的）之后，以及在光化学和酸碱化学参数的UV/维斯光谱测定之后，主要通过核磁共振光谱法对氢键进行表征，将在pH光开关的结构优化中具有重要意义。