Figure 1.

(a) Schematic representation of di-aromatic compounds obtained by SPPS with Fmoc chemistry. Conjugates contain an aromatic framework consisting of two 2-naphthylalanine (2-Nal) residues, an ethoxylic linker (L₆) formed by six PEG units and bifunctional and macrociclic chelating agent (DOTA) for gadolinum (III) coordination. (b and c) Fluorescence spectra of 2Nal₂ and Gd-2Nal₂ in 0.025–20.0 mg/mL concentration range. Samples were excited at λ = 280 nm and recorded between 290 and 500 nm.