Interplay of Anion‐π⁺ and π⁺‐π⁺ Interactions in Novel Pyrido[2,1‐a]isoquinolinium‐Based AIEgens ‐ Substituent‐ and Counterion‐Dependent Fluorescence Modulation and Applications in Live Cell Mitochondrial Imaging**

Abstract

Recently, the concept of anion‐π+ interactions has witnessed unique applications in the field of AIEgen development. In this contribution, we disclose a consolidated study of a library of N‐doped ionic AIEgens accessed through silver‐mediated cyclization of pyridino‐alkynes. A thorough photophysical, computational and crystallographic study has been conducted to rationalize the observed substituent‐ and counterion‐dependent fluorescence properties of these luminogens. We further elucidate the prominent role of anion‐π+ interactions, π+‐π+ interactions and other non‐covalent interactions, in inhibiting the undesired ACQ effect. Finally, we have also demonstrated the application of selected AIEgens for imaging of mitochondria in live cells.

Non-covalent interactions (NCIs) in π-conjugated functional materials: advances and perspectives

“…In addition to the aforementioned potential applications of NCIs in OE research, they have also been utilized in areas such as nanophotonic, bioimaging, sensing, catalysis, and fuel storage research 108–112 The potential of NCI in single-molecule electronics has also been tested. 113 In molecular electronics, dimer formed by π-stacking is detrimental and lowers the electrical conductance.…”

Tandem C–H Annulation Reaction of Benzaldehydes and Aminobenzoic Acids with Two Equivalents of Alkyne toward Isocoumarin-Conjugated Isoquinolinium Salts: A Family of Organic Luminophores

“…13 C{ 1 H} NMR (101 MHz, CDCl 3 ): δ 165.0, 162.9, 155. 5, 151.6, 149.2, 146.7, 146.6, 140.8, 138.3, 135.9, 131.9, 130.9, 130.6, 128.3, 125.8, 125.0, 121.2, 120.3, 119.5, 118.9, 118.7, 113.9, 113.1, 24.2, 19.4, 18.9, 17.3, 14.8, 14.5, 12.8, 12.6 2- (3,. Colorless solid.…”

“…(Z)-6- (4)(5)(6)(7)3]dioxol-6-ylidene)amino)phenyl) -3,4-diethyl-1H-isochromen-1-one (5mda). Yellow solid.…”

“…2- (3, (d,J = 8.7 Hz,1H), 8.07 (dd, J = 8.4, 2.2 Hz, 1H), 3.60 (q, J = 7.1 Hz, 2H), 3.33−3.12 (m, 2H), 2.78−2.61 (m, 4H), 1.47 (t, J = 7.5 Hz, 3H), 1.30−1.25 (m, 6H), 1.16 (t, J = 7.5 Hz, 3H). The 13 C{ 1 H} NMR spectrum was not recorded due to the small amount of 4paa.…”

“…Isocoumarins and isoquinolinium salts are privileged heterocyclic scaffolds that have received particular attention of chemists due to their rich photophysical activity . In particular, these compounds have been found to demonstrate aggregation-induced emission properties, which provide their application for bioimaging and photodynamic anticancer therapy, as well as the construction of organic light-emitting diodes . Moreover, Bin with co-workers showed the efficiency of the isocoumarin framework as an acceptor block in donor–acceptor–donor host compounds for TADF-emitters .…”