Emergent Behavior of a Photoswitchable Solute in a Biphasic Solvent System.

Due to thermal E/Z isomerization, hydrazones in solution typically exist in thermodynamic equilibria between their isomers. Irradiation of such solutions leads to photostationary states that may differ from the equilibrium distribution. Operating such switchable hydrazones in a biphasic system of two immiscible solvents introduces three new degrees of freedom: the E/Z equilibrium in the second solvent and two equilibria for distribution of each of the isomers between the solvents.

Polymorphs of phenazine hexacyanoferrate(II) hydrate: supramolecular isomerism in a 2D hydrogen-bonded network.

The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)[HFe(CN)][HFe(CN)]·2(phen)·2HO, are reported. The polymorphs are comprised of (Hphen)[HFe(CN)] trimers and (Hphen)[(phen)(HO)][HFe(CN)] hexamers connected into two-dimensional (2D) hydrogen-bonded networks through strong hydrogen bonds between the [HFe(CN)] and [HFe(CN)] anions. The layers are further connected by hydrogen bonds, as well as through π-π stacking of phenazine moieties.

Redox Control over Acyl Hydrazone Photoswitches.

Photoisomerization provides a clean and efficient way of reversibly altering physical properties of chemical systems and injecting energy into them. These effects have been applied in development of systems such as photoresponsive materials, molecular motors, and photoactivated drugs. Typically, switching from more to less stable isomer(s) is performed by irradiation with UV or visible light, while the reverse process proceeds thermally or by irradiation using another wavelength.

Antiparallel Dynamic Covalent Chemistries.

The ability to design reaction networks with high, but addressable complexity is a necessary prerequisite to make advanced functional chemical systems. Dynamic combinatorial chemistry has proven to be a useful tool in achieving complexity, however with some limitations in controlling it. Herein we introduce the concept of antiparallel chemistries, in which the same functional group can be channeled into one of two reversible chemistries depending on a controllable parameter.

An "ingredients" approach to functional self-synthesizing materials: a metal-ion-selective, multi-responsive, self-assembled hydrogel.

New methodology for making novel materials is highly desirable. Here, an "ingredients" approach to functional self-assembled hydrogels was developed. By designing a building block to contain the right ingredients, a multi-responsive, self-assembled hydrogel was obtained through a process of template-induced self-synthesis in a dynamic combinatorial library.