Volume 7, Issue 1-4

No abstract available

No abstract available

The transient character of oxygen-heme intermediates in catalytic cycles of P450 enzymes hinders their trapping and direct characterization under physiological conditions. It was shown that biomimetic studies, using P450 enzyme mimics, offer valuable information about mechanistic details of dioxygen activation and oxygen atom transfer reactions by cytochrome P450 enzymes occurring in nature. In this context, the present review focuses on the kinetic and mechanistic studies of ‘peroxo-shunt’ reactions involving simple or more advanced P450 mimics as an approach to catch and characterize oxo-iron reactive species responsible for the oxygen transfer reactions by cytochrome P450. We demonstrate that the generation and reactivity of oxo-iron reactive intermediates derived from even simple or structurally remote cytochrome P450 mimics can be tuned to that observed for native enzymes through the selection of appropriate reaction conditions. In particular, the factors that determine the mode of O–O bond cleavage in the iron(III)-peroxo porphyrin adduct and the stabilization/reactivity of the O–O bond cleavage products are reviewed and discussed in detail.

The establishment of new functional materials and the provision of a specific bundle of electronic, magnetic, optical, mechanical, or catalytic properties are the key tasks in the field of modern, inorganic materials chemistry. Functional properties of solid, inorganic materials are first and foremost determined by their composition and crystal structure. Other parameters such as morphology (size and shape) are of immense relevance as well. One can observe that the complexity of functional inorganic materials is increasing substantially. Therefore, rather than preparation, the synthesis of tailor-made materials is highly desirable. This approach requires an understanding of mechanistic aspects that can be used in a rational synthesis of the materials with required properties. It is demonstrated in the domain of bioinorganic materials that superior functionality can be achieved by controlled assembly of (biological) building blocks in a hierarchical manner. In analogy, in the current context, synthesis refers to the simultaneous control over the assembly of a variety of inorganic tectons on different length scales. A basic requirement is that desirable structural motifs that have been constructed in previous steps remain intact in the course of the entire synthesis. The synthetic concept that is discussed here addresses the hierarchy of activation energies and length scales. Molecular precursors are interpreted as initial tectons that are transferred into nanoscaled seeds for the formation of a desired, complex material. The tools of molecular inorganic chemistry can be applied to ensure that the latter transformation occurs at such conditions that the information about composition and structure is retained. Then, the seeds represent tectons for higher organization on the supramolecular scale. This requires the ability for fine control of surface energies and curvatures through noncovalent interactions. Thus, the concept developed in this work provides a bridge among solid-state chemistry, inorganic molecular chemistry, surface chemistry, and colloid chemistry. Because of the bridging character and the underlying hierarchy ranging from the pm scale to the mesoscale, the term ‘chemical architectonics’ has been selected for the description of the main topic of the current work. Thus, chemical architectonics can be understood as the coordinated use of different tools of chemical synthesis for the assembly of nanostructured materials fulfilling function.