Aeruginic acid (H 2 L), a weakly fluorescent natural ionophore, was synthesized via one-pot mechanochemical grinding at room-temperature. This sulfur containing intermediate siderophore showed unique specificity towards Zn 2 + in 100% water at physiological pH even in presence of other challenging metal ions particularly, paramagnetic metal ions such as Fe 3 + , Co 2 + , Ni 2 + , and Cu 2 + . H 2 L also displayed a naked eye observable instant color change under UV light in presence of Zn 2 + , in aqueous solution and in solid phase as well. The receptor H 2 L with 49 nM limit of detection, upon excitation at 360 nm, reversibly binds one equivalent Zn 2 + as evidenced from Job's plot, ESI-MS, and 1 H NMR spectroscopy. Being fully water soluble, non-toxic, and permeable in nature, this natural ionophore can visualize Zn 2 + in the gastrointestinal tract of live whole brine shrimp Artemia. We are not aware of any report on bio-imaging of Zn 2 + in living organism.

A halotolerant bacterium Acinetobacter soli (MTCC 5918), isolated from the salt farm of our institute, was found to secrete a novel siderophore under iron deprivation conditions. A combination of multinuclear one and two dimensional NMR spectroscopies in conjunction with mass technique revealed that the siderophore, we named acinetoamonabactin (1), is a triscatechol derivative of tris(aminomethyl)methylamine.