Fluorescent Solvatochromism of 2-Aminotryptanthrin

Abstract

Tryptanthrin derivatives, which are known antimicrobial agents, were synthesized, and their absorption and fluorescence spectral behaviors were investigated. Our results showed that 2-aminotryptanthrin exhibits both a high fluorescence quantum yield and large positive fluorescent solvatochromism.

Spectral Characteristics of Highly Fluorescent 2-(<i>N,N</i>-dimethylamino)tryptanthrin

“…The absorption and fluorescence spectra of T2NH2 are shown in Figures 2, 3, and 4 of Ref. [8]. In comparison with T2NH2, T2NMe2, in which a dimethylamino group was installed instead of an amino group, exhibited red-shifted a, max and f, max values.…”

“…T2NH2 possesses a planar, polar structure with effective intramolecular charge transfer (ICT) between the carbonyl group of the five-membered ring and the amino group. The large fluorescent solvatochromism is attributable to the influence of the ICT, although stabilization by hydrogen bonding would also contribute in the case of protic solvents [8]. T2NH2 and its derivatives have widespread potential applications in highly diverse fields, such as labeling reagents, chemosensors, laser dyes, photosensitizers, and fluorescent organic devices.…”

Photophysical Properties of the 2-Hydroxytryptanthrin and Its Sodium Salt as Near-infrared Dyes for Fluorescent Imaging

“…The absorption maxima (λa,max) of T2NH2 are at 447 nm in toluene and 464 nm in methanol, whereas the emission maxima (λf,max) are at 516 nm in toluene and 632 nm in methanol. 5 Therefore, we plan to shift the λa,max and λf,max of T2NH2 to longer wavelengths by accelerating the intramolecular charge transfer (ICT).…”

Naphthalene Ring-Fused 2-Aminotryptanthrin as a Fluorescent Chemosensor for Al³⁺

“…The molecular structures of Naph-T2NH2 and T2NH2 were calculated using density functional theory (DFT) [12]. The electron densities of the corresponding highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) surfaces of Naph-T2NH2 and T2NH2 are shown The strong fluorescence of T2NH2 can be attributed to the influence of intramolecular charge transfer (ICT) between the carbonyl group of the five-membered ring and the amino group [5]. Therefore, in T2NH2, the electrons are localized on the amino group in the HOMO and on the carbonyl group of the five-membered ring in the LUMO.…”

“…1b) has excellent photophysical properties such as a wide wavelength absorption and emission in the visible region, as well as a high fluorescence quantum yield (f) [4]. The fluorescence spectra of T2NH2 in various polarity solvents demonstrated large, positive fluorescent solvatochromism, indicating that T2NH2 exhibits a longer fluorescence wavelength in highly polar solvents compared to nonpolar solvents [5]. T2NH2 and its derivatives have widespread potential applications in diverse fields, such as labeling reagents, chemosensors, laser dyes, photosensitizers, and fluorescent organic devices [6].…”