In the present paper, we synthesize lead bromide 2D perovskites (n=1) including the four diammonium cations mentioned above. We grew single crystals and we solved the crystal structures, and we report a detailed investigation of the optical properties, providing correlations with the bonding details and the interplay between the organic and inorganic components, which is a crucial step for the understanding of structure-property relationships in monoammonium-based 2D perovskites.