Engineering cyanine aggregation and self-assembly to access exceptionally red-shifted organic chromophores

在化学系大分子、超分子和纳米化学项目的支持下，加州大学洛杉矶分校的Ellen M. Sletten教授和Justin R. Caram教授正在开发新的荧光化合物，这种化合物可以在电磁波谱的短波红外区域发光。短波红外线对人眼来说是不可见的，但可以通过特殊的摄像机检测到。这些波的一个主要优点是它们可以穿过组织，并用于复杂生物体的成像。在改善光纤网络的长途电信方面也看到了更多的机会。在本研究的第一部分中，将制备有机小分子并对其进行结构修饰，以达到期望的红外吸收和发射性能。这些光物理性质将通过在溶液中产生异常红移聚集体的自组装而被放大几个数量级。为了帮助实验设计和加速发现，计算模型将用于将这些聚集体的结构与其电子特性联系起来。与该奖项相关的研究活动将增加更广泛的参与，并使高中生、本科生和研究生在合成有机化学和光谱学方面得到培训。创建PHOTONbooth和参与“照亮分子世界”活动将提供有吸引力的策略，以激发公众对科学的兴趣，并向大洛杉矶地区的参与者介绍STEM概念。本研究将聚焦于菁氨酸聚集和自组装，以获得电磁波谱短波红外区域（SWIR）的异常红移有机发色团。在第一个目标中，将通过杂原子取代和延长聚甲基链来合成改性的单体菁染料。这种结构修饰将促进1,300 nm以上的SWIR j -聚集体，并有助于研究这种聚集体目前的两个限制，即低量子产率（目标2）和它们需要在基质或纳米颗粒中稳定以用于稀/复杂环境（目标3）。新的结构将使用圆形和线性二色性进行研究，并通过计算模拟来获取激子结构，并将它们与光物理性质联系起来。这项工作，如果成功的话，将提供对发色团-发色团耦合和发射，带边j聚集体形成所需的远程顺序的基本见解。与这项工作相关的有机SWIR j聚集体有潜力在被认为对眼睛安全的波长范围内开发廉价、环保和可扩展的纳米技术。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professors Ellen M. Sletten and Justin R. Caram of the University of California-Los Angeles are developing new fluorescent chemical compounds that emit light in the shortwave infrared region of the electromagnetic spectrum. Shortwave infrared waves are invisible to the human eye but can be detected by special cameras. A major advantage of these waves is that they can pass through tissue and be used for imaging in complex organisms. Additional opportunities are also seen in improving long-haul telecommunications of fiber optical networks. In the first part of this research, small organic molecules will be prepared and structurally modified to achieve desired absorption and emission properties in the infrared region. These photophysical properties will then be amplified several orders of magnitude through self-assembly in solution yielding exceptionally red-shifted aggregates. To aid in experimental design and speed discovery, computational modelling will be used to correlate the structure of these aggregates with their electronic properties. The research activities associated with this award will increase broadening participation and enable training of high school, undergraduate, and graduate students in synthetic organic chemistry and spectroscopy. The creation of a PHOTONbooth and participation in “Illuminating the World of Molecules” events will provide attractive strategies to generate public interest in science and introduce STEM concepts to participants in the greater Los Angeles area. This research will focus on cyanine aggregation and self-assembly to access exceptionally red-shifted organic chromophores for the shortwave infrared region (SWIR) region of the electromagnetic spectrum. In the first objective, modified monomeric cyanine dyes will be synthesized through heteroatom substitution and lengthening of the polymethine chain. This structural modification will promote SWIR J-aggregates above 1300 nm and facilitate investigation of two of the current limitations of such aggregates, namely low quantum yield (objective 2) and their need to be stabilized in a matrix or nanoparticle for use in dilute/complex environments (objective 3). New structures will be investigated using circular and linear dichroism and modelled computationally to access excitonic structures and correlate them with photophysical properties. This work, if successful, will provide fundamental insight on the chromophore-chromophore coupling and long-range order necessary for emissive, band edge J-aggregate formation. The organic SWIR J-aggregates associated with this work have the potential to develop inexpensive, environmentally friendly and scalable nanotechnology in a wavelength regime deemed to be eye safe.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.