Table 1. Chemical shift difference (absolute value of ppm in the absence – ppm in the presence of metal ions) is reported for the resonances of both preacinetobactin and acinetobactin during titration.

1H nuclei†	preacinetobactin‡	Acinetobactin
a	0.34	0.07
b	0.17	0.02
d	n.r.	n.r.
e	0.16	n.r.
f	~0.4§	n.r.
g	0.56	n.r.
h	0.12	n.o.
i	0.27	0.15
l	0.27	0.30
m	0.39	0.28

The titration performed in acetate buffered saline with Ga³⁺. Reported values correspond to 0.5 and 0.3 eq. Ga³⁺ in the case of preacinetobactin and acinetobactin, respectively.^† Labels refer to Figure 3C.^‡ Two resolved resonances were observed for protons g, h, i, l and m, due to two different L₂M species (see the main paper). Average values are reported here.^§ Complex overlapped with residual water’s resonance. Value estimated by comparison with additional titration performed in DMSO. n.r.: not sufficiently resolved. n.o.: difference not observed.