Schiff bases represent an essential class in organic
chemistry with antitumor, antiviral, antifungal, and antibacterial
activities. The synthesis of Schiff bases requires the presence of an
organic base as a catalyst such as piperidine. Base-free synthesis of
organic compounds using a heterogeneous catalyst has recently
attracted more interest due to the facile procedure, high yield, and
reusability of the used catalyst. Herein, we present a comparative study
to synthesize new Schiff bases containing indole moieties using
piperidine as an organic base catalyst and Au@TiO2 as a heterogeneous
catalyst. In both methods, the products were isolated in high yields and
fully characterized using different spectral analysis techniques. The
catalyst was reusable four times, and the activity was slightly decreased.
The presence of Au increases the number of acidic sites of TiO2,
resulting in CO polarization. Yields of the prepared Schiff bases in the presence of Au@TiO2 and piperidine were comparable.
However, Au@TiO2 is an easily separable and recyclable catalyst, which would facilitate the synthesis of organic compounds without
applying any hazardous materials. Furthermore, the luminescence behavior of the synthesized Schiff bases exhibited spectral shape
dependence on the substituent group. Interestingly, the compounds also displayed deep-blue fluorescence with Commission
Internationale de l’Éclairage (CIE) coordinates of y < 0.1. Thus, these materials may contribute to decreasing the energy
consumption of the emitting devices.