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. In this work we developed a method of rapid and tunable Z→E isomerization of C=N bond in acyl hydrazones, using aromatic thiols as nucleophilic catalysts. As thiols can be oxidized into catalytically inactive disulfides, the isomerization rates can be controlled via the oxidation state of the catalyst, which, together with the UV irradiation, provides orthogonal means to control the E/Z state of the system. As a proof of this concept, we have applied this method to control the diversity of acyl hydrazone based dynamic combinatorial libraries.

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. The system can be switched between gel and solution by light, redox reactions, pH, temperature, mechanical energy and sequestration or addition of Mg(II) salt.

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. Such systems allow both for achieving complexity, by combinatorial chemistry, and addressing it, by switching from one chemistry to another by controlling an external parameter. In our design the two antiparallel chemistries are thiol–disulfide exchange and thio-Michael addition, sharing the thiol as the common building block. By means of oxidation and reduction the system can be reversibly switched from predominantly thio-Michael chemistry to predominantly disulfide chemistry, as well as to any intermediate state. Both chemistries operate in water, at room temperature, and at mildly basic pH, which makes them a suitable platform for further development of systems chemistry.

Hexacyanoferrates are well-known to form metal−organic frameworks by coordination to metal atoms or acting as hydrogen bond acceptors. In this paper we report a new type of hexacyanoferrate self-assembly, based on direct hydrogen bonding of partially protonated hexacyanoferrate anions. By preparing a series of 15 hexacyanoferrates with various organic bases, we have found that protonated hexacyanoferrates (present in 10 structures) readily form chains (two structures), two-dimensional (four structures), or three-dimensional networks (four structures), whereby the dimensionality of the network generally increases with the protonation degree of the hexacyanoferrates. The exact mode of the self-assembly, including the network type, depends on fine interplay of the pK a value of the base, its steric properties, and the stoichiometry of the formed solid.

Morpholine adducts of nickel(II), cobalt(II), and manganese(II) benzoylacetonates, as well as a morpholine solvate of manganese(II) benzoylacetonate, were prepared and characterized by X-ray diffraction and thermal analysis. All four compounds crystallize in the P2 1 /c space group with two complex molecules per unit cell. The morpholine solvate, along with the two adduct molecules, also contains four solvent morpholine molecules in the unit cell. The non-solvate compounds are isostructural, with crystal structures comprising 2D networks formed by C-HÁÁÁO hydrogen bonding between phenyl rings and morpholine oxygen atoms. The topology of these networks can be described as intersecting C 2 2 (24) chains forming R 4 4 (48) rings. Networks with the same topology are also present in the solvate, but they are heavily distorted due to the presence of solvent morpholine molecules. Thermogravimetric analysis shows similar behavior of the non-solvate compounds upon thermal decomposition, with three degradation steps which can be related to gradual loss of morpholine molecules and subsequent overall decomposition. Decomposition of the solvate also proceeds in several steps, the first of which can be related to loss of solvent morpholine molecules and the further steps are analogous to those in the non-solvate compounds.