Fig. 2. Absorption and emission spectra of 1 (20 μM) with 10 equiv. of an amino acid (Pro, Thr, Val, Leu, Asn, Trp, Ile, Ala, His, Glu, Tyr, Lys, Met, Asp, Phe, Arg, Gly, Gln, Ser) or biothiol (Cys, Hcy, GSH) in solution (DMSO/10 mM PBS pH 7.4, 1 : 3 v/v) incubated for 5 min at r.t. λ _ex: 518 nm.