ABSTRACT:We report a multi-component self-assembling system based on 1,3:2,4-dibenzyldene-D-sorbitol (DBS) derivatives which form gels as the pH is lowered in a controlled way. The two DBS gelators are functionalized with carboxylic acids the first in the 4-position of the aromatic rings (DBS-CO 2 H), the second having glycine connected through an amide bond and displaying a terminal carboxylic acid (DBS-Gly). Importantly, these two self-assembling DBS-acids have different pK a values, and as such, their self-assembly is triggered at different pHs. Slowly lowering the pH of a mixture of gelators using glucono--lactone (GdL) initially triggers assembly of DBS-CO 2 H, followed by DBS-Gly a good degree of kinetic self-sorting is achieved. Gel formation can also be triggered in the presence of diphenyliodonium nitrate (DPIN) as a photoacid under UV irradiation. Two-step acidification of a mixture of gelators using (a) GdL and (b) DPIN assembles the two networks sequentially. By combining this approach with a mask during step (b), multidomain gels are formed, in which the network based on DBS-Gly is positively patterned into a pre-existing network based on DBS-CO 2 H. This innovative approach yields spatially-resolved multidomain multi-component gels based on programmable lowmolecular-weight gelators, with one network being positively written into another.

Herein we report unprecedented location-dependent, size-selective binding to designed lanthanide (Ln 3+ ) sites within miniature protein coiled coil scaffolds. Not only do these engineered sites display unusual Ln 3+ selectivity for moderately large Ln 3+ ions (Nd to Tb), for the first time we demonstrate that selectivity can be location-dependent and can be programmed into the sequence. A 1 nm linear translation of the binding site towards the N-terminus can convert a selective site into a highly promiscuous one. An X-ray crystal structure, the first of a lanthanide binding site within a coiled coil to be reported, coupled with CD studies, reveal the existence of an optimal radius that likely stems from the structural constraints of the coiled coil scaffold. To the best of our knowledge this is the first report of location-dependent metal selectivity within a coiled coil scaffold, as well as the first report of locationdependent Ln 3+ selectivity within a protein.

Herein we report unprecedented location-dependent, size-selective binding to designed lanthanide (Ln 3+ ) sites within miniature protein coiled coil scaffolds. Not only do these engineered sites display unusual Ln 3+ selectivity for moderately large Ln 3+ ions (Nd to Tb), for the first time we demonstrate that selectivity can be location-dependent and can be programmed into the sequence. A 1 nm linear translation of the binding site towards the N-terminus can convert a selective site into a highly promiscuous one. An X-ray crystal structure, the first of a lanthanide binding site within a coiled coil to be reported, coupled with CD studies, reveal the existence of an optimal radius that likely stems from the structural constraints of the coiled coil scaffold. To the best of our knowledge this is the first report of location-dependent metal selectivity within a coiled coil scaffold, as well as the first report of locationdependent Ln 3+ selectivity within a protein.

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