Photophysical Properties of Fluorescent 2-(Phenylamino)-1,10-phenanthroline Derivatives † .

Autor: Teixeira RI; Instituto de Química, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil., da Silva RB; Instituto de Química, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil., Gaspar CS; Instituto de Química, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil., de Lucas NC; Instituto de Química, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil., Garden SJ; Instituto de Química, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
Jazyk: angličtina
Zdroj: Photochemistry and photobiology [Photochem Photobiol] 2021 Jan; Vol. 97 (1), pp. 47-60. Date of Electronic Publication: 2020 Jul 28.
DOI: 10.1111/php.13303
Abstrakt: The present study details the experimental and theoretical characterization of the photophysical properties of 14 examples of 2-(phenylamino)-1,10-phenanthrolines (1). The absorption spectra of 1 are substituent-dependent but in a general manner present absorption bands at wavelengths of ~230; ~300; ~335 and a shoulder at ~380 nm. Electron-donating groups (EDG) and electron-withdrawing groups (EWG), respectively, result in bathochromic and hypsochromic shifts. Compounds 1 are highly luminescent, in contrast to phenanthroline, and emit in the region between 350 and 500 nm with substituent-dependent λ max emission. The emission spectra show a redshift for EDG (4-OMe 62 nm; 4-Me 19 nm) and a blueshift for EWG (4-CN 41 nm; 4-CF 3 38 nm) relative to the emission of the unsubstituted parent compound 1a. Plotting the λ max EM against Hammett σ+ constants gave an excellent linear correlation demonstrating the electron-deficient nature of the excited state and how the substituents (de)stabilize S 1 . Theoretical calculations revealed a HOMO-LUMO π-π* electronic transition to S 1 which in combination with difference (S 1 -S 0 ) in electron density maps revealed charge-transfer character. Strongly electron-withdrawing substituents switch off the charge transfer to give rise to a local excitation.
(© 2020 American Society for Photobiology.)
Databáze: MEDLINE
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