Engineering Cyanine Aggregation and Self-assembly to Access Exceptionally Red-shifted Organic Chromophores

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 mammals. Additional opportunities are also seen in improving long-haul telecommunications of fiber optical networks. This research aims to provide important fundamental insights to developing design principles for short wavelength infrared emission compounds and expanding the potential of these materials in optical and photonic technologies. This project will provide a rich training ground for undergraduate students, graduate students and postdoctoral researchers. Students in grade school will benefit from PHOTONbooth and Illuminating the World of Molecules activities, which provide attractive strategies to generate public interest in science. Specifically, this research will focus on cyanine aggregation and self-assembly to access exceptionally red-shifted organic chromophores for the shortwave infrared region (SWIR) of the electromagnetic spectrum. While theory suggests J-aggregates are superradiant, this has remained elusive for shortwave infrared aggregates. In the first objective, the research team will perform structure-property relationship studies on known superradiant trimethine dyes to understand the functionality needed for superradiance. The team will then apply these findings to trimethines with heterocycles that induce red-shifts or the heptamethine dyes. In the second objective, the team will focus on the effects of structure and disorder in controlling superradiance. Novel spectroscopies, models, and molecules will be pursued. In the final objective, the team will explore alternative paths to enhance the emission of J-aggregates via coupling light and matter interactions. 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.