Structure‐Property Correlation of C10‐(H)‐Arylated‐N‐(pyren‐1‐yl)‐picolinamide Regioisomers towards Cu²⁺ and Fe³⁺ Sensing

Abstract

Recently developed C10‐(H)‐arylated‐N‐(pyren‐1yl)‐picolinamide compounds have been investigated spectroscopically for their photophysical properties and metal ion sensing abilities. Two sets of regioisomers were selected based on their molar absorptivities and fluorescence quantum yields and classified into two series I methoxy group at meta‐ and para‐ position of phenyl ring, and series II methyl group at meta‐ and para‐ position of phenyl ring. Additionally, for better understanding on structure‐property relationship, a comparison study with C‐10 unsubstituted compound was also conducted. All compounds exhibited characteristic absorption and emission responses only towards Cu2+ and Fe3+ ions among all the screened metals. While the reference compound and those with methoxy substituent displayed a fluorescence turn‐off behaviour, compounds with methyl groups showed fluorescence turn‐on response through excimer formation at ∼550 nm in the presence of Cu2+ and Fe3+. Sensing studies were performed to elucidate structure‐property relationship and to obtain limits of detection, binding constants and fluorescence quenching constants. Temperature‐dependent fluorescence studies were performed to distinguish the type of excimers produced by two compounds in series II with the metal ions.

Light-controlled shape-changing azomacrocycles exhibiting reversible modulation of pyrene fluorescence emission

“…Using these fluorescence data and the Benesi–Hildebrand equation corresponding to a constant concentration of pyrene and increasing amounts of AM2b , we estimated the association constants for the two species in the EE and ZZ states of the azomacrocycle. 26 The results showed 4.2 × 10 4 ± 2.1 × 10 3 M −1 and 7.6 × 10 4 ± 3.4 × 10 3 M −1 for the AM2b –pyrene complex in the EE - and ZZ -isomeric forms of the macrocycle, respectively (see Section S6.2 in the ESI†). Due to the quenching behavior of the azomacrocycle in the EE state, we considered the Stern–Volmer plot for deducing the quenching constant.…”

Photophysical characterization and the self-assembly properties of mono- and bis-pyrene derivatives for cell imaging applications

“…7 In general, the photophysical properties of pyrene derivatives can be extensively controlled by using classic supramolecular chemistry tools, in terms of their attitude to assemble and respond to various stimuli or external conditions. For this reason, pyrene derivatives have been applied for the sensing of metal cations 8 and anions, 9 in photonic devices and organic electronics. 10 Pyrene derivatives have also been extensively used as fluorescent probes for DNA studies and more biological oriented applications.…”