Enzymnachbildungen auf der Basis supramolekularer Koordinationschemie

Abstract

In der aktuellen supramolekularen Koordinationschemie können makromolekulare Komplexe mit Enzymeigenschaften synthetisiert werden. Dieser Aufsatz behandelt solche Strukturen, die nicht in erster Linie die aktiven Zentren von Enzymen nachbilden sollen, sondern von deren Eigenschaften und Funktionen inspiriert sind. Die Komplexe werden in konvergenter Weise mit modularen Methoden in hohen Ausbeuten synthetisiert, wobei ihre Größe, Form und Eigenschaften maßgeschneidert werden können. Viele der Strukturen zeigen eine Reaktivität und Spezifität, die an natürliche Systeme erinnern, und manche haben Funktionen, die über jene ihrer Vorbilder hinausgehen.

Enhanced Catalytic Activity of Self‐Assembled‐Monolayer‐Capped Gold Nanoparticles

“…[26] Surprisingly, when the number of surface metal atoms was taken into consideration, the self-aggregated 10Dod-AuNP catalyst showed approximately three times higher activity (TOF = 13 900 h −1 , Table 1, entries 3 and 4), despite the low accessibility of the catalyst surface by the substrate molecules. These results suggest that the alkanethiol-SAM either: 1) acts as an enzyme-like reaction space showing catalytic activity similar to porous coordination compounds, [8,[27][28][29][30] or 2) favors the encapsulation and subsequent access of substrate molecules via co-operative intermolecular interactions, as in the case of metalloenzymes ( Figure 1c). [1] To investigate the intrinsic catalytic activity of dodecanethiol-SAM, we developed a dodecanethiol-SAM-coated quartz substrate (Dod-quartz) by means of the self-assembly and a silane-coupling reaction [31] of dodecyltrimethoxysilane with a piranha-cleaned quartz substrate.…”

“…These results strongly suggest that the alkanethiol-SAM interface around the AuNPs acts as a hydrophobic encapsulating nanospace in which linear and long-alkyl-chain-substituted molecules are better accommodated, resulting in higher reactivity for these substrates. The aromatic silanes showed a higher reactivity than the aliphatic silanes for all the AuNP catalysts (Table 2, entries 5,6,8), with DMPS being the most reactive within 1 h of the reaction ( Table 2, entry 8). When using 10Cit-AuNP, primary alcohols such as ethanol, n-butanol, n-hexanol, and benzyl alcohol showed similar reactivities (Table 2; 13.5%, 14.7%, 14.1%, and 13.2% yields, entries 7, 8, 11, and 12, respectively), in contrast to sterically bulky secondary (s-butanol: 1.9% yield) and tertiary alcohols (t-butanol: 0% yield) ( Table 2, entries 9, 10).…”

“…[1] Much effort has been devoted to mimic molecular-encapsulation-based catalysis since the mechanism of this catalytic reaction provides an ideal and promising model to develop highly active catalysts. In this sense, semiartificial approaches based on the use of natural proteins (e.g., apoenzyme), wherein a metal-complex catalyst is incorporated into the reaction sites as a cofactor, [2,3] and artificial approaches, in which large molecules such as polymers, [4][5][6] dendrimers, [7] supramolecular hosts, [8,9] and mesoporous materials [10] provide the protein-like reaction space required for enhancing the catalytic activity of the metal complex, have been adopted. As a result of the growing interest in metallic nanoparticle (MNP) catalysts, [11,12] there are numerous reports on the incorporation of MNPs into a reaction space constructed within different architectures such as polymers, [13] dendrimers, [14] micelles, [15] and mesoporous materials.…”

Switching through Coordination‐Coupled Proton Transfer

“…In the 1:1 complex Zn(QPH-Z) [14] (Figure 3 a), the Zn 2+ cation is pentacoordinated with one QPH unit, one triflate anion, and one water molecule. The QPH unit still maintains its planar geometry.…”

“…This process opens up a broad range of opportunities for the design of switching systems that function under mild (nonacidic) conditions, the study of reactions related to the photosynthetic pathway [2] and CDFs, [3] and the construction of artificial functional mimics of biological systems. [19] Received: November 7, 2010…”