Highly Efficient Artificial Light‐Harvesting Systems Constructed in Aqueous Solution Based on Supramolecular Self‐Assembly

Abstract

Highly efficient light-harvesting systems were successfully fabricated in aqueous solution based on the supramolecular self-assembly of a water-soluble pillar[6]arene (WP6), a salicylaldehyde azine derivative (G), and two different fluorescence dyes, Nile Red (NiR) or Eosin Y (ESY). The WP6-G supramolecular assembly exhibits remarkably improved aggregation-induced emission enhancement and acts as a donor for the artificial light-harvesting system, and NiR or ESY, which are loaded within the WP6-G assembly, act as acceptors. An efficient energy-transfer process takes place from the WP6-G assembly not only to NiR but also to ESY for these two different systems. Furthermore, both of the WP6-G-NiR and WP6-G-ESY systems show an ultrahigh antenna effect at a high donor/acceptor ratio.

Hierarchical Assembly of Peptoid‐Based Cylindrical Micelles Exhibiting Efficient Resonance Energy Transfer in Aqueous Solution

“…These results clearly show that efficient energy transfer occurred from NBD donors to RB acceptors, achieving ah igh level of performance compared to other aqueous light-harvesting systems. [21] Conclusion Theresults of this investigation show that introducing CD headgroups into amphiphilic peptoid sequences leads to as elf-assembly of ar ange of hierarchical structures from 1D worm-like or cylindrical micelles to 2D films to 3D intertwined ribbons of well-aligned cylindrical micelles,w ith the end state dependent on substrate chemistry and solution conditions.U niform 1D cylindrical micelles form in bulk aqueous solution and on SiO 2 surfaces,2 Df ilms form via coalescence of worm-like micelles on mica at pH 2.8 to 4.3, and 3D architectures consisting of intertwined ribbons overlaying 2D films form on mica at pH 4.3 in the presence of Ca 2+ .T he results also provide insight into the assembly mechanisms of these hierarchical structures.I na ll cases,t he first stage of Pep-cd assembly appears to utilize spheroidal precursors in solution, which are themselves likely to be micelles of the amphiphiles,a st he basic building unit. However,t here are distinct differences in assembly pathway and kinetics depending on the substrate and solution conditions.M ost striking is the degree to which Ca 2+ leads to cooperative assembly,s ot hat worm like micelles on mica evolve into highly convoluted islands,w hich spread laterally to cover the surface,and cylindrical micelles assemble on the resulting films to form coaligned ribbons.M oreover,t his cooperativity is manifest as an on-linear dependence of coverage on time,w ith high Pep-cd levels accelerating the rate of coverage and accentuating the non-linearity and high Ca 2+ levels inhibiting the onset of adsorption while still accelerating the subsequent rate of coverage.I nc ontrast, increases in pH slow the kinetics of assembly,p resumably as ar esult of repulsion arising from the high negative surface charge of mica and deprotonated state of the Pep-cd carboxylic groups at high pH.…”

Applications of Pillar[n]arene‐Based Supramolecular Assemblies

“…[19].C opyright 2018 Wiley-VCH Verlag GmbH & Co.K GaA. [20].C opyright2 018 Wiley-VCH Verlag GmbH & Co.K GaA. Reproduced with permission from Ref.…”

Advanced Functional Materials Constructed from Pillar[n]arenes

“…In a follow-up study on light-harvesting systems, we constructed a new system in aqueous solution ( Figure 2). [14] This system was based on the self-assembly of a water-soluble pillar [6]arene (WP6), a salicylaldehyde azine derivative (G), and two kind of fluorescence dyes, Nile Red (NiR) or Eosin Y (ESY). It should be noted that G is highly emissive in aggregates through the combined mechanism of aggregation induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT).…”

“…[3,9] In recent years, our group has been committed to developing advanced functional materials based on pillar[n] arenes. We are especially interested in constructing drug delivery system, [10][11][12][13] light harvesting system, [14,15] and functional organogels and hydrogels. [16] In this review, we will summarize part of our previous work on pillar [n]arenes materials and also some excellent related work reported by other groups.…”