Fluorescent H-Aggregate Vesicles and Tubes of a Cyanine Dye and Their Potential as Light-Harvesting Antennae

Abstract

H-aggregates of π-conjugated dyes are an ordered supramolecular structure. However, the non-fluorescence behavior of H-aggregates greatly limits their potential applications. In this paper, we report the formation of fluorescent H-aggregates with vesicular and tubular morphologies by the self-assembly of 3,3′-diethylthiacarbocyanine iodide (DiSC2(3)) in ammonia/methanol mixtures. The transition from H-aggregate vesicles to H-aggregate tubes can be achieved by increasing the volume fraction of methanol in the mixtures. H-aggregate vesicles and tubes show two blue-shifted absorption bands and strong fluorescence, which result from the inclined arrangement of DiSC2(3) molecules. Furthermore, light-harvesting complexes are formed by adding dopamine (DA)-quinone (acceptor) in synthetic urine with H-aggregate vesicles or tubes. Our results show that H-aggregate tubes are more efficient than H-aggregate vesicles in transferring excited electrons to DA-quinone acceptors.

White light emission from helically stacked humin-mimic based H-aggregates in heteroatom free carbon dots

“…[36][37][38] This unexpected fluorescence from H-aggregates is believed to arise from ground state symmetry breaking due to the imperfect face-to-face arrangement of molecular fluorophores, which makes the transition feasible from the lower-energy exciton state. 39 Unfortunately, the weak fluorescence of H-aggregates due to the small oscillator strength of the lowest Frenkel state makes detailed observation of the dynamics very challenging. 40 Although several instances of WLE from molecular aggregates have been reported in the literature, most of them are studied on known dye-based systems.…”

Conjugated Polyelectrolyte‐Based Complex Fluids as Aqueous Exciton Transport Networks

“…[1][2][3][4][5][6][7][8][9] Recently, much work has gone into the use of self-assembly to form components of lightharvesting systems, like electronic energy-transfer antennae. [10][11][12][13][14][15][16][17] Here the self-assembled components are arranged through non-covalent interactions to directionally guide the transport of electronic excited states (excitons), thereby mimicking exciton transport in photosynthetic organisms.…”