Siderophore-mimicking macrocyclic peptoids were synthesized. Peptoid 3 with intramolecular hydrogen bonds showed an optimally arranged primary coordination sphere leading to a stable catecholate-iron complex. The tris(catecholato) structure of 3-Fe(III) was...

In this paper, we report a photoactivatable, artificial peroxidase system based on a photocaging approach. The photocaged Mn 2 (bpmp) (bpmp: 2,6-bis((bis(2-pyridylmethyl)amino)-methyl)-4-methylphenolate) complex was developed by a simple design and synthesis of the corresponding bpmp ligand via the introduction of the 1-(o-nitrophenyl)-ethyl (NPE) group, a well-known photoremovable protecting group. Following 365 nm light irradiation of the resulting complex, the intrinsic peroxidaselike activity of the raw Mn 2 (bpmp) was effectively restored. Interestingly, the degree of activation of the raw Mn 2 (bpmp) system was found to be altered by varying the irradiation time and/ or the light intensity, providing us with a method to tune the in situ reaction kinetics ad libitum. The photocaged Mn 2 (bpmp) complex was further utilized for light-controlled hydrogelation by exploiting the ability of Mn 2 (bpmp) to catalyze the synthesis of hydrogels under physiological conditions with a phenolfunctionalized hydrophilic polymer as a precursor, and the photocontrollability of this catalytic activity using an external light source. Spatial control of light irradiation using a photomask enabled site-specific activation of peroxidase-like activity, allowing the preparation of a desired shape of the hydrogel. In addition, the mechanical properties of the resultant hydrogel, such as the adhesion strength, could be regulated depending on the light exposure time of the pre-gel solution containing the precursor, H 2 O 2 , and photocaged Mn 2 (bpmp). Furthermore, the biocompatibility of the hydrogel synthesized using the photocaged Mn 2 (bpmp) was confirmed by an in vitro assay.