Bailey Austin D, Deshmukh Arundhati P, Bradbury Nadine C, Pengshung Monica, Atallah Timothy L, Williams Jillian A, Barotov Ulugbek, Neuhauser Daniel, Sletten Ellen M, Caram Justin R
Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, 90024, USA.
Department of Chemistry and Biochemistry, Denison University, Granville, OH, 43023, USA.
Nanoscale. 2023 Feb 23;15(8):3841-3849. doi: 10.1039/d2nr05747f.
Excitonic chromophore aggregates have wide-ranging applicability in fields such as imaging and energy harvesting; however their rational design requires adapting principles of self-assembly to the requirements of excited state coupling. Using the well-studied amphiphilic cyanine dye C8S3 as a template-known to assemble into tubular excitonic aggregates-we synthesize several redshifted variants and study their self-assembly and photophysics. The new pentamethine dyes retain their tubular self-assembly and demonstrate nearly identical bathochromic shifts and lineshapes well into near-infrared wavelengths. However, detailed photophysical analysis finds that the new aggregates show a significant decline in superradiance. Additionally, cryo-TEM reveals that these aggregates readily form short bundles of nanotubes that have nearly half the radii of their trimethine comparators. We employ computational screening to gain intuition on how the structural components of these new aggregates affect their excitonic states, finding that the narrower tubes are able to assemble into a larger number of arrangements, resulting in more disordered aggregates ( less superradiant) with highly similar degrees of redshift.
激子发色团聚集体在成像和能量收集等领域具有广泛的适用性；然而，其合理设计需要将自组装原理应用于激发态耦合的要求。以经过充分研究的两亲性花菁染料C8S3为模板（已知其可组装成管状激子聚集体），我们合成了几种红移变体，并研究了它们的自组装和光物理性质。新型五甲川染料保留了其管状自组装结构，并在近红外波长范围内表现出几乎相同的红移和线形。然而，详细的光物理分析发现，新型聚集体的超辐射显著下降。此外，冷冻透射电子显微镜显示，这些聚集体很容易形成短的纳米管束，其半径几乎是其三甲川对照物的一半。我们采用计算筛选来了解这些新型聚集体的结构成分如何影响其激子态，发现较窄的纳米管能够组装成更多的排列方式，从而导致具有高度相似红移程度的更无序聚集体（超辐射性较低）。
