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  • Pyridine-terminated low gap π-conjugated oligomers: design, synthesis, and photophysical response to protonation and metalation
Title: Pyridine-terminated low gap π-conjugated oligomers: design, synthesis, and photophysical response to protonation and metalation
Reported here is the design and synthesis of among the first pyridine terminated acceptor–donor–acceptor–donor–acceptor (A–D–A–D–A) based π-conjugated oligomers, EH_DPP_2T_Pyr ( 1 ), EH_II_2T_Pyr ( 2 ), and EH_II_1T_Pyr ( 3 ). The molecules incorporate thiophenes as electron donors, isoindigo/diketopyrrolopyrrole as electron acceptors, and are capped with pyridine, a weak electron acceptor, on both ends. All target oligomers show attractive photophysical properties, broad absorption in the visible region ( λ max = 636 nm, 575 nm, and 555 nm, for 1 , 2 , and 3 , respectively) and emission which extends to the IR region (emission λ max = 734 nm and 724 for 1 and 2 , respectively). Given the pyridine nitrogens, the optoelectronic properties of the compounds can be further tuned by protonation/metalation. All compounds show a bathochromic shift in visible absorption and fluorescence quenching upon addition of trifluoroacetic acid (TFA). Similar phenomena are observed upon addition of metals with a particularly strong response to Cu 2+ and Pd 2+ as indicated by Stern–Volmer analysis ( e.g. , for Pd 2+ ; K sv = 7.2 × 10 4 M −1 ( λ = 673 nm), 8.5 × 10 4 M −1 ( λ = 500 nm), and 1.1 × 10 5 ( λ = 425 nm) for 1 , 2 , and 3 , respectively). The selective association of the molecules to Cu 2+ and Pd 2+ is further evidenced by a color change easily observed by eye and under UV light, important for potential use in colorimetric sensing.  more » « less
Award ID(s):
1828064
PAR ID:
10295928
Author(s) / Creator(s):
; ; ; ; ;
Date Published:
Journal Name:
Organic Chemistry Frontiers
Volume:
5
Issue:
21
ISSN:
2052-4129
Page Range / eLocation ID:
3170 to 3177
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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