Electron-deficient π-conjugated functional dyes lie at the heart of organic optoelectronics. Adding nitro groups to aromatic compounds usually quenches their fluorescence via inter-system crossing (ISC) or internal conversion (IC). While strong electronic coupling of the nitro groups with the dyes ensures the benefits from these electron-withdrawing substituents, it also leads to fluorescence quenching. Here, we demonstrate how such electronic coupling affects the photophysics of acceptor–donor–acceptor fluorescent dyes, with nitrophenyl acceptors and a pyrrolo[3,2-
A twist in the non-slanted H-mers to control π-conjugation in 2-dimensions and optical properties
Understanding the structural parameters that determine the extension of π-conjugation in 2-dimensions is key for controlling the optical, photophysical, and electronic properties of 2D-π-conjugated materials. In this article, three non-slanted H-mers including a donor–acceptor H-mer (H-mer-3) with an increase in dihedral angle (twist) between the strands and rungs are synthesized and studied. These non-slanted H-mers represent the repeat units of 2D-π-conjugated materials. H-mer-3, containing donor-strands and an acceptor-rung, is an unexplored donor–acceptor architecture in both slanted and non-slanted H-mers. The H-mers displayed both acid and base dependent optical properties. While the rungs have a little impact on the H-mer absorption spectra they play a key role in the emission and fluorescence lifetime. H-mer-3 ( i.e. , donor–acceptor H-mer) shows a higher Stokes shift and fluorescence lifetime than the other two H-mers. The twist and the presence of an electron deficient rung in H-mer-3 facilitated an intramolecular charge transfer in the excited state from the strands to the electron deficient rung, and therefore control over the H-mer emission properties. The lack of insulating pendant chains, reduced π–π interactions in thinfilms, and longer fluorescence lifetimes make these H-mers interesting candidates for various electronic and optoelectronic applications.
- Award ID(s):
- 1944184
- Publication Date:
- NSF-PAR ID:
- 10220706
- Journal Name:
- Materials Advances
- Volume:
- 1
- Issue:
- 8
- Page Range or eLocation-ID:
- 2917 to 2925
- ISSN:
- 2633-5409
- Sponsoring Org:
- National Science Foundation
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