Synergistic Enhancement of Electron-Accepting and -Donating Ability of Nonconjugated Polymer Nanodot in Micellar Environment

Abstract

Understanding the fundamental electron-transfer dynamics in photoactive carbon nanoparticles (CNPs) is vitally important for their fruitful application in photovoltaics and photocatalysis. Herein, photoinduced electron transfer (PET) to and from the nonconjugated polymer nanodot (PND), a new class of luminescent CNP, has been investigated in the presence of N,N-dimethylaniline (DMA) and methyl viologen (MV) in homogeneous methanol and sodium dodecyl sulfate (SDS) micelles. It has been observed that both DMA and MV interact with the photoexcited PND and quench the PL intensity as well as excited-state lifetime in bulk methanol. While in bulk methanol, purely diffusion-controlled PET from DMA to MV via PND has been observed, the mechanism and dynamics differ significantly in SDS micelles. In contrast to homogeneous methanol medium, a distinct synergic effect has been observed in SDS micelles. The presence of both DMA and MV enhances the electron-accepting and -donating abilities of PND in SDS micelles. Time-resolved photoluminescence (PL) measurements reveal that the PET process in SDS micelles is nondiffusive in nature mainly due to instantaneous electron transfer at the confined micellar surface. These results have been explained on the basis of heterogeneous microenvironments of SDS micelles which compartmentalize the donor and acceptor inside its micellar pseudo phase. The present findings provide valuable insights into the intrinsic relation between redox and PL properties of nonconjugated PND.

Zwitterionic Poly(vinylidene fluoride) Graft Copolymer with Unexpected Fluorescence Property

“…PVDM-1 solution shows a fluorescence property with a low quantum yield (1%) in water, whereas PVDMS exhibits high fluorescence quantum yield of 8%, supporting more aggregation-induced emission due to zwitterion formation. This is very much comparable to the polymeric systems without any fluorophore reported earlier. − Zhu et al reported 1.26% quantum yield from poly­(vinyl alcohol)-based nonconjugated polymer dots, and recently Bhattacharya et al reported 8.4% quantum yield using nonconjugated polymer nanodots . It is to be noted here that the emission peak of PVDMS occurs at a much lower wavelength than that of PVDM-1.…”

“…This is very much comparable to the polymeric systems without any fluorophore reported earlier. 51 It is to be noted here that the emission peak of PVDMS occurs at a much lower wavelength than that of PVDM-1. A probable reason may be the stabilization of ground state due to delocalization of π electrons for aggregation, causing higher energy emission.…”

Femtosecond Upconversion Study of Interfacial Electron Transfer from Photoexcited CsPbBr3 Perovskite Nanocrystal to Rhodamine 6G

“…As discussed in the preceding paragraph, NC emission is significantly quenched in the presence of r6G. There could be two possible reasons for this quenching: (1) PET from conduction band (CB) of photoexcited NC to LUMO of r6G (Scheme ) − and/or (2) Förster resonance energy transfer (FRET) from photoexcited NC (donor) to ground state r6G (acceptor). − Despite the good overlap of donor (NC) emission with acceptor (r6G) absorption (Figure S6), which is a prerequisite of an efficient FRET, no r6G emission (at 570 nm) can be observed as a result of quenching of NCs emission (Figure S7). Therefore, quenching of NC emission in our case is attributed to PET only, despite the fact that criteria of both PET and FRET are equally satisfied.…”

Biocompatible pH-Responsive Luminescent Coacervate Nanodroplets from Carbon Dots and Poly(diallyldimethylammonium chloride) toward Theranostic Applications

“…Control steady-state PL measurement reveals that sequestration of EtBr results in PL quenching of CDs inside these LNDs (Figure S7). The possible mechanism behind the observed PL quenching might be due to the photoinduced electron transfer from photoexcited CDs to EtBr dyes . Therefore, the weaker blue signal from EtBr-loaded LNDs is due to the luminescence quenching of CDs inside LNDs and not due to the disassembly of LNDs.…”

“…The possible mechanism behind the observed PL quenching might be due to the photoinduced electron transfer from photoexcited CDs to EtBr dyes. 56 Therefore, the weaker blue signal from EtBr-loaded LNDs is due to the luminescence quenching of CDs inside LNDs and not due to the disassembly of LNDs. Nevertheless, uniform red emission from intact NDs clearly signifies preferential loading of EtBr inside these LNDs.…”