Self-Assembled π-Nanotapes as Donor Scaffolds for Selective and Thermally Gated Fluorescence Resonance Energy Transfer (FRET)

Abstract

Self-assembled nanotapes of a few tailor-made oligo(p-phenylenevinylene)s (OPVs) have been prepared and used as supramolecular donor scaffold to study the fluorescence resonance energy transfer (FRET) to a suitable acceptor. In nonpolar solvents, FRET occurs with nearly 63-81% efficiency, exclusively from the self-assembled OPVs to entrapped Rhodamine B, resulting in the quenching of the donor emission with concomitant formation of the acceptor emission at 625 nm. The efficiency of FRET is considerably influenced by the ability of the OPVs to form the self-assembled aggregates and hence could be controlled by structural variation of the molecules, and polarity of the solvent. Most importantly, FRET could be controlled by temperature as a result of the thermally reversible self-assembly process. The FRET efficiency was significantly enhanced (ca. 90%) in a xerogel film of the OPV1 which is dispersed with relatively less amount of the acceptor (33 mol %), when compared to that of the aggregates in dodecane gel. FRET is not efficient in polar solvents due to weak self-organization of the chromophores. These results indicate that energy transfer occurs exclusively from the self-assembled donor and not directly from the individual donor molecules. The present study illustrates that the self-assembly of chromophores facilitates temperature and solvent controlled FRET within pi-conjugated nanostructures.

Chirality and energy transfer amplified circularly polarized luminescence in composite nanohelix

“…However, in the self-assembled nanohelix system, the amplified interactions between L-1 donor and BPEA acceptor facilitated the process. There has been report that the energy transfer process occurred exclusively from nanostructured π-conjugated self-assemblies but not directly from the individual donor molecules38. In present example, the process can occur from both the self-assembled aggregates and individual molecule.…”

“…4). Considering that π–π stacking in aggregates always induced bathochromic shift of emission peak and quenched fluorescence emission related to the formation of excimer or exciplex in general π-conjugated luminescent systems36373839, L-1 with stable emission peak position is a proper energy donor in the self-assembly system. Keeping the same concentration of L-1 at 2 mM in DMSO/H 2 O (v/v=9/1), by gradually adding BPEA to L-1 gel, the emission of L-1 decreased while the emission peak of BPEA increased with an isostilbic point at 467 nm (Fig.…”

Challenges and breakthroughs in recent research on self-assembly

“…An interesting target for functionalization of self-assemblies of aromatic oligomers is the potential control of optical properties based on supramolecular structure variation. Ajayaghosh et al also investigated fluorescence resonance energy transfer (FRET) between the tape-like structure of a few tailor-made oligo (p-phenylenevinylene) derivatives (donor, figure 26C) and entrapped rhodamine B (acceptor) [191]. The efficiency of FRET was influenced considerably by the ability to form self-assembled aggregates of the oligo (p-phenylenevinylene) compound and so control could be realized by variation of solvent polarity and/or temperature.…”

Improvement of short circuit current density by intermolecular interaction between polymer backbones for polymer solar cells

“…[10][11][12][13] In particular, OPVs have been in the spotlight owing to their low cost, light weight and flexibility.…”