In this thesis the preparation of a fluorescent indicator for the detection of intracellular H2S is described. The 1,8-naphthalimide system was chosen as the fluorophore in the fluorescent indicator design process, while the azide group was chosen as the receptor responsible for the reaction with the target analyte, H2S. The basic naphthalimide system is structurally modified by introduction of aniline derivatives on the nitrogen atom. 4-bromo-1,8-naphthalic anhydride was selected as the starting compound for the preparation of the target compounds, while p-methylaniline and p-chloroaniline were selected as aniline derivatives. For the preparation of target derivatives synthetic pathway which implies preparation of the azide derivative of 4-bromo-1,8-naphthalanhydride, compound 1, and its reaction with selected aniline derivatives was used. This synthetic route resulted in the successful preparation of compound 2, with a methyl group on the aryl part of the molecule, while compound b, with a chlorine atom on the aryl part of the molecule, was not successfully prepared using the proposed synthetic route. With the aim of preparing compound b, a novel synthetic route was proposed, which involves the reaction of the starting compound, 4-bromo-1,8-naphthalanhydride with p-chloroaniline, followed by the introduction of an azide group into the structure of the naphthalimide derivative. Compound b was not successfully prepared even by the novel proposed synthetic route. The target product, compound 2, was used for fluorescence detection of generated H2S. The structures of the prepared compounds were assumed by NMR spectroscopy ( 1H and 13C).