Exploiting complexity to implement function in chemical systems

Abstract

This feature article reflects a personal overview of the importance of complexity as an additional parameter to be considered in chemical research, being illustrated with selected examples in molecular recognition and catalysis.

Dynamic Surface Layer Coiled Coil Proteins Processing Analog-to-Digital Information

“…Of particular interest, direct manipulations of native protein sequences and the de novo design of non-native sequences are being implemented for the development of molecules and assemblies with properties and functions that differ fromand sometimes even surpassthose of their natural counterparts. − Investigations in this arena have traditionally targeted thermodynamically stable, “static” unimolecular architectures or small complexes. However, inspired by the dynamic nature of protein networks in cells, scientists have recently expanded the repertoire of protein functions through the preparation and characterization of relatively complex synthetic networks. − We now show that further progress toward real-world applications can be achieved via dynamic assembly of proteins into extended arrays on solid-state surfaces, akin to a 2D monolayer. Our strategy is based on conceptually mimicking the functionality associated with the 2D layers of proteins covering the surface of prokaryotic cells, also known as s-layer proteins. − The dynamic assembly of these natural proteins is affected by various chemical cues (e.g., binding to calcium ions), and the resulting (para)­crystalline layers, which are ∼10 nm thick, serve as an additional barrier and communication platform between the cell and its environment.…”

Interdependent Dynamic Nitroaldol and Boronic Ester Reactions for Complex Dynamers of Different Topologies

“…[32][33][34][35][36][37][38][39][40] Moreover, the unique chemistries of reversible chemical bonds enable transfer, inhibition, or emergence of systemic properties, typically based on multiple dynamic processes operating in conjunction. [41][42][43][44] In this regard, dynamic covalent polymers (dynamers) are gaining a lot of attention due to their many features, such as self-assembly/self-organization, adaptive/responsive functions, and emergent properties. [1,15,[45][46][47][48][49] This is perhaps especially the case in biomedical applications and materials with functions inspired by biological systems.…”

A Degenerate Metal-Templated Catalytic System with Redundant Functional Groups for the Asymmetric Aldol Reaction

“…We reasoned that, as in biological systems, this unique combination of properties should lead to robustness, which would manifest as improved function. 22 − 24 …”

“…21 In contrast, we used a conceptually different approach consisting of a dynamic self-assembled system, wherein a mixture of catalytic ligands and a metal would generate a sufficient amount of the catalytically effective bifunctional species among other species in equilibrium of lesser, if any, catalytic importance. 22 Therefore, we embarked on the development of a dynamic catalytic system for the asymmetric aldol reaction using two pyridine 16,17 or two bipyridine 18 ligands that contained either prolinamide (enamine-forming) or thiourea (hydrogen bonding) groups for the bifunctional catalysis. We used zinc or copper to assemble the tetrahedral complexes in a dynamic fashion.…”

“…We reasoned that, as in biological systems, this unique combination of properties should lead to robustness, which would manifest as improved function. 22 Following these ideas, herein we present the research that led us to identify new bipyridine ligands for the metaltemplated highly asymmetric aldol reaction under low catalyst loadings. We synthesized the chiral 5,5′-bis(prolinamide)-2,2′bipyridine ligand 9, which we call bipyPro 2 , from the known 5,5′-diamino-2,2′-bipyridine (see the SI).…”