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教授正在开发在电磁光谱的短波红外区发光的新的荧光化合物。短波红外线是肉眼看不见的，但可以被特殊的摄像机探测到。这些波的一个主要优势是它们可以穿透组织，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。在这项研究的第一部分，将制备有机小分子并对其进行结构修饰，以实现所需的红外吸收和发射性能。然后，这些光物理性质将通过在溶液中的自组装放大几个数量级，产生异常红移的聚集体。为了帮助实验设计和加速发现，将使用计算模型来将这些聚集体的结构与它们的电子性质联系起来。与该奖项相关的研究活动将增加更广泛的参与，并使高中、本科生和研究生能够接受合成有机化学和光谱学方面的培训。创建PHOTON展台并参与“照亮分子的世界”活动将提供有吸引力的战略，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。这项研究将集中在花菁的聚集和自组装，以获得电磁光谱的短波红外区(SWIR)的异常红移的有机生色团。在第一个目标中，通过杂原子取代和聚亚甲基链的加长来合成改性单体菁染料。这一结构修改将促进SWIR J-聚集体超过1300纳米，并有助于调查此类聚集体目前的两个限制，即低量子产率(目标2)和它们需要稳定在基质或纳米颗粒中以用于稀薄/复杂环境(目标3)。新的结构将使用圆和线性二色性进行研究，并通过计算建模来获得激子结构并将它们与光物理性质相关联。这项工作，如果成功，将提供基本的见解，发色团-发色团的耦合和长程有序所需的发射，带边J聚集体的形成。与这项工作相关的有机SWIR J-聚集体具有在被认为是眼睛安全的波长制度下开发廉价、环境友好和可扩展的纳米技术的潜力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.