1-Amino-2-hydroxy-4-naphthalenesulfonic acid based Schiff bases or naphtho[1,2-d]oxazoles: Selective synthesis and photophysical properties

• Prepared Schiff bases and naphtho[1,2-d]oxazoles based on 1-amino-2-hydroxy-4-naphthalenesulfonic acid.
• Temperature dependent selective synthesis was shown with regard to presence or absence of o-hydroxy group.
• The compounds were investigated photophysically in different solvents.

A series of Schiff base and naphtho[1,2-d]oxazole derivatives were selectively synthesized via condensation reaction of 1-amino-2-hydroxy-4-naphthalenesulfonic acid and benzaldehyde derivatives at same conditions. The synthesized compounds were then characterized by using 1HNMR, 13CNMR, FTIR spectroscopies and elemental analyses. It was seen that the Schiff bases generated in the presence of OH group at ortho position of benzaldehyde derivatives. However, the products were naphtho[1,2-d]oxazoles in other cases. Then, the synthesized compounds were photophysically investigated by UV absorption and fluorescence emission spectroscopies. As a result, these Schiff bases have shown long wavelength absorption (λmax: 386 nm) and emission (λmax: 429–437 nm) effect while synthesized naphtho[1,2-d]oxazole derivatives have a set of absorption (λmax: about 296, 308, 320 nm) and emission maxima (λmax: 378–395 nm) at lower wavelength.

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