A Theoretical and Experimental Study on the Potential Luminescent and Biological Activities of Diaminodicyanoquinodimethane Derivatives

Abstract

Recently, several studies have demonstrated that diaminodicyanoquinone derivatives (DADQs) could present interesting fluorescence properties. Furthermore, some DADQs under the solid state are capable of showing quantum yields that can reach values of 90%. Besides, the diaminodiacyanoquinone core represents a versatile building block propense either to modification or integration into different systems to obtain and provide them unique photophysical features. Herein, we carried out a theoretical study on the fluorescence properties of three different diaminodicyanoquinodimethane systems. Therefore, time-dependent density functional theory (TD-DFT) was used to obtain the values associated with the dipole moments, oscillator strengths, and the conformational energies between the ground and the first excited states of each molecule. The results suggest that only two of the three studied systems possess significant luminescent properties. In a further stage, the theoretical insights were confirmed by means of experimental measurements, which not only retrieved the photoluminescence of the DADQs, but also suggest a preliminary and promising antibacterial activity of these systems.

Fluorescence Quenching in J-Aggregates through the Formation of Unusual Metastable Dimers

“…Here, we present results on the complex aggregation behavior and unusual photophysical properties of diaminodicyanoquinone (DADQ) compounds in solution. DADQs are a class of redox-active organic molecules derived from 7,7,8,8-tetracyanoquinodimethane (TCNQ) displaying notably high dipole moments of up to 30 debye, which may additionally exhibit large fluorescence quantum yields (QYs) exceeding 90%. − In this study, we examine concentration-dependent absorption spectra and study the emission properties of a series of non-, singly-, and doubly-methylated DADQ compounds. This reveals redshifted absorption bands upon aggregation which did not show any relevant fluorescence in excitation-emission matrices.…”