New Arylamino-Substituted 2,1,3-Benzothiadiazoles: Synthesis, Structure, and Fluorescent Response to Cu(II) Cations

Interaction of 4,7-dibromo-2,1,3-benzothiadiazole with methyl p-aminobenzoate under Buchwald–Hartwig amination conditions yields new derivatives: 4,7-di((4-methoxycarbonylphenyl)amino)-2,1,3-benzothiadiazole (1) and 4-bromo-7-((4-methoxycarbonylphenyl)amino)-2,1,3-benzothiadiazole (2). The structures of the compounds is determined by single-crystal XRD, NMR, and elemental analysis. The photophysical properties of the obtained compounds are studied both in solution and in the solid state. The luminescence of 1 is selectively quenched in the presence of Cu(II) cations, thereby highlighting prospects of using this compound as a fluorescent sensor.