Photophysical study of the Dibenzylideneacetones and 3-Benzylidenethiochroman-4-ones

The Benzylideneacetones as part of a broad group of compounds, some of them of natural origin and found in several plant species [1], are of great interest in pharmaceutical and polymers areas [2, 3]. Also, these compounds have optical properties of interest in photonics [4,5]. Recently, it has been demostrated that 1,3-diketonate ligands in complex compounds with lanthanide ions, containing groups of donors and acceptors of electrons, are responsible for the absorption and emission of light in the near infrared (NIR) [6]. Dibenzylideneacetones (DBA) derivatives have been studied for the last two decades in group donors and acceptors of electrons located in the molecule, particularly, due to their large molecular hyperpolarizability, depending on where they are located in the molecule [7]. For this reason, these systems can lead to a wide range of applications in photonics (second harmonic generation (SHG), mixing of frequency, electro-optical modulation and parametric effects among others). The basic structure of organic materials with nonlinear optical properties (NLO) is based on a set of π bonds and the electronic effect which induce to charge delocalization. A molecular system with high conjugation and appropriate group donors and acceptors of electrons can obtain a great optical response [8]. In this work, group donors and acceptors of electrons attached to both extremes of a molecule such as DBA or 3-Benzylidenethiochroman-4-ones (BTC) are used in forming highly conjugated pushpull systems. The behavior of these groups acts like an on-off switch which activates or not radiative relaxation processes.