Tuning Photophysical Properties via Positional Isomerization of the Pyridine Ring in Donor–Acceptor-Structured Aggregation-Induced Emission Luminogens Based on Phenylmethylene Pyridineacetonitrile Derivatives

Abstract

A series of aggregation-induced emission (AIE)-featured phenylmethylene pyridineacetonitrile derivatives named o-DBCNPy ((Z)-3-(4-(di-p-tolylamino)phenyl)-2-(pyridin-2-yl)acrylonitrile), m-DBCNPy ((Z)-3-(4-(di-p-tolylamino)phenyl)-2-(pyridin-3-yl)acrylonitrile), and p-DBCNPy ((Z)-3-(4-(di-p-tolylamino)phenyl)-2-(pyridin-4-yl)acrylonitrile) have been synthesized by tuning the substitution position of the pyridine ring. The linkage manner of the pyridine ring had influences on the molecular configuration and conjugation, thus leading to different photophysical properties. The absorption and fluorescence emission peak showed a bathochromic shift when the linking position of the pyridine ring changed from the meta to the ortho and para position. Meanwhile, o-DBCNPy exhibited the highest fluorescence quantum yield of 0.81 and the longest fluorescence lifetime of 7.96 ns as a neat film among all three isomers. Moreover, non-doped organic light-emitting diodes (OLEDs) were assembled in which the molecules acted as the light-emitting layer. Due to the relatively prominent emission properties, the electroluminescence (EL) performance of the o-DBCNPy-based OLED was superior to those of the devices based on the other two isomers with an external quantum efficiency (EQE) of 4.31%. The results indicate that delicate molecular modulation of AIE molecules could endow them with improved photophysical properties, making them potential candidates for organic photoelectronic devices.

Chemical Regulation of Fluorescence Lifetime

“…28 Lu and co-workers designed a series of phenylmethylene pyridineacetonitrile derivatives bearing a triphenylamine (TPA) structure and pyridine ring with the nitrogen atom at the ortho (36), meta (37), and para (38) position in Figure 5c. 29 In tetrahydrofuran (THF), their fluorescence lifetimes were only approximately 1 ns, but in the solid state, these lifetimes were significantly extended. Specifically, the fluorescence lifetime of 37 was prolonged to 3.32 ns, and that of 38 was extended to 5.94 ns (Figure 5c).…”

“…Triphenylamines possessed a characteristic propeller-like structure and were frequently employed in the construction of AIE fluorophores . Lu and co-workers designed a series of phenylmethylene pyridineacetonitrile derivatives bearing a triphenylamine (TPA) structure and pyridine ring with the nitrogen atom at the ortho ( 36 ), meta ( 37 ), and para ( 38 ) position in Figure c . In tetrahydrofuran (THF), their fluorescence lifetimes were only approximately 1 ns, but in the solid state, these lifetimes were significantly extended.…”

“…Copyright 2018, Royal Society of Chemistry. (c) Reprinted with permission from ref . Copyright 2023, Multidisciplinary Digital Publishing Institute.…”

1,2-Bis-(diphenylphosphino)ethane (dppe) appended cobalt(iii)-dithiocarbamates as single source precursors of cobalt sulfide/cobalt phosphide composites: apt electrocatalytic materials for water splitting reactions

“…RuO 2 and IrO 2 for the OER and Pt and Pt-based alloys for the HER. 5–8 However, their limited availability, high-cost and poor robustness limit their real-world applications. 9 Therefore, rational design and synthesis of robust, cost-effective, and active catalysts for water splitting are urgently needed.…”

Metal–organic frameworks (MOFs) as apt luminescent probes for the detection of biochemical analytes

“…8,9 MOFs offer benefits such as adjustable porosity, high specific surface area, and customizable architectures when compared to typical porous materials such as porous carbon, porous catalysts and porous polymers. 10–14 All these properties could (at least theoretically) address the need to develop novel sensing materials with high sensitivity, excellent selectivity, fast response times, enhanced stability and reusability. 15 Hence, MOF materials have promising future in the fields of bioimaging, adsorption, 16,17 catalysis, 18 magnetism, 19 sensing, 20,21 and drug delivery.…”