Compartmentalization and Photoregulating Pathways for Incompatible Tandem Catalysis

Abstract

This contribution describes an advanced compartmentalized micellar nanoreactor that possesses a reversible photoresponsive feature and its application toward photoregulating reaction pathways for incompatible tandem catalysis under aqueous conditions. The smart nanoreactor is based on multifunctional amphiphilic poly­(2-oxazoline)­s and covalently cross-linked with spiropyran upon micelle formation in water. It responds to light irradiation in a wavelength-selective manner switching its morphology as confirmed by dynamic light scattering and cryo-transition electron microscopy. The compartmental structure renders distinct nanoconfinements for two incompatible enantioselective transformations: a rhodium–diene complex-catalyzed asymmetric 1,4-addition occurs in the hydrophilic corona, while a Rh-TsDPEN-catalyzed asymmetric transfer hydrogenation proceeds in the hydrophobic core. Control experiments and kinetic studies showed that the gated behavior induced by the phototriggered reversible spiropyran to merocyanine transition in the cross-linking layer is key to discriminate among substrates/reagents during the catalysis. The smart nanoreactor realized photoregulation to direct the reaction pathway to give a multichiral product with high conversions and perfect enantioselectivities in aqueous media. Our SCM catalytic system, on a basic level, mimics the concepts of compartmentalization and responsiveness Nature uses to coordinate thousands of incompatible chemical transformations into streamlined metabolic processes.

Nanoconfinement Effects of Micellar Media in Asymmetric Catalysis

“…Two incompatible catalysts were spatially confined in the two portions of the nanostructure: in the hydrophilic corona a rhodium‐diene complex catalyzed asymmetric 1,4‐addition, while in the hydrophobic core a Rh‐TsDPEN catalyzed asymmetric transfer hydrogenation (Scheme 9). [64] The overall process achieved multi‐chiral products with high conversions and outstanding enantioselectivities in aqueous media (up to 99% ee , up to 98:2 d.r., yields up to 99%). The nanoreactor allowed to by‐pass the intrinsic incompatibility between the catalysts employed via compartmentalization and enabled photo‐regulation of the desired reaction pathway, mimicking the concepts of compartmentalization and responsiveness of natural streamlined metabolic processes.…”

Trendbericht Physikalische Chemie 2022: Reaktionsdynamik lichtgetriebener Reaktionen

“…In der Natur finden chemische Reaktionen typischerweise in zellulären Kopartimenten statt, welche die Reaktionsräume aufspannen (zum Beispiel Mitochondrien, Chloroplasten). In künstlichen Systemen bedeutet das, die Reaktanden in einem kleinen dreidimensionalen Raum einzuschließen, etwa in Wassertropfen, 12) polymerbasierte Mizel-len, 13) oder hydrophobe Lipiddoppelschichten. 14) In der Regel ist dieser Reaktionsraum zusätzlich beengt, sodass intermolekulare Stöße mit erhöhter Andere Studien nutzten die weiche Matrix der Phospholipidmembranen, um -ähnlich wie in der natürlichen Photosynthese -Licht zu sammeln und Elektronen innerhalb der Membran zu transferieren (Abbildung 4b,c).…”

A Generalized Kinetic Model for Compartmentalization of Organometallic Catalysis

“…Last, we set F V ˛[30, 600] s À1 , whose range is estimated based on the diffusion coefficient of 9 Â 10 À10 m 2 s À1 from tabulated organometallic catalysts, 48,49 as well as the geometry and properties of reported microscopic compartments in porous materials, supramolecular assemblies, nanoscopic micelles, and the use of nanowire array electrode in our previous work (see ESI Section 2 †). [17][18][19][20]29,50,51 Overall, our selection of kinetic values here represents an organometallic catalytic cycle whose oxidative addition step is turnover-limiting and the deactivation of yielded Cat À A intermediate is the most critical issue, while the fast reductive elimination leaves the deactivation of Cat À B species secondary in terms of g and TOF. With varying values of F V and changing ratios between the values of k 2 and k e2 , the trend of compartmentalization's efficacy can be unveiled.…”