A Zinc(II) Photocage Based on a Decarboxylation Metal Ion Release Mechanism for Investigating Homeostasis and Biological Signaling

Metal ion signaling in biology has been studied extensively with ortho‐nitrobenzyl photocages; however, the low quantum yields and other optical properties are not ideal for these applications. We describe the synthesis and characterization of NTAdeCage, the first member in a new class of Zn²⁺ photocages that utilizes a light‐driven decarboxylation reaction in the metal ion release mechanism. NTAdeCage binds Zn²⁺ with sub‐pM affinity using a modified nitrilotriacetate chelator and exhibits an almost 6 order of magnitude decrease in metal binding affinity upon uncaging. In contrast to other metal ion photocages, NTAdeCage and the corresponding Zn²⁺ complex undergo efficient photolysis with quantum yields approaching 30 %. The ability of NTAdeCage to mediate the uptake of ⁶⁵Zn²⁺ by Xenopus laevis oocytes expressing hZIP4 demonstrates the viability of this photocaging strategy to execute biological assays.     

Perovskites with the Framework‐Forming Xenon

The Group 18 elements (noble gases) were the last ones in the periodic system to have not been encountered in perovskite structures. We herein report the synthesis of a new group of double perovskites KM(XeNaO₆) (M=Ca, Sr, Ba) containing framework‐forming xenon. The structures of the new compounds, like other double perovskites, are built up of the alternating sequence of corner‐sharing (XeO₆) and (NaO₆) octahedra arranged in a three‐dimensional rocksalt order. The fact that xenon can be incorporated into the perovskite structure provides new insights into the problem of Xe depletion in the atmosphere. Since octahedrally coordinated Xe^VIII and Si^IV exhibit close values of ionic radii (0.48 and 0.40 Å, respectively), one could assume that Xe^VIII can be incorporated into hyperbaric frameworks such as MgSiO₃ perovskite. The ability of Xe to form stable inorganic frameworks can further extend the rich and still enigmatic chemistry of this noble gas.