Chemically Fueled Dissipative Self‐Assembly that Exploits Cooperative Catalysis

Abstract

In living systems, dissipative processes are driven by the endergonic hydrolysis of chemical fuels such as nucleoside triphosphates. Now, through a simple model system, a transient self‐assembled state is realized by utilizing the catalytic effect of histidine on the formation and breaking of ester bonds. First, histidine facilitates the ester bond formation, which then rapidly co‐assembles to form a self‐supporting gel. An out‐of‐equilibrium state is realized owing to the cooperative catalysis by the proximal histidines in the assembled state, driving the second pathway and resulting in disassembly to sol. Cooperative effects that use the dual role of imidazoles as nucleophile and as proton donor is utilized to achieve transient assemblies. This simple system mimics the structural journey seen in microtubule formation where the substrate GTP facilitates the non‐covalent assembly and triggers a cooperative catalytic process, leading to substrate hydrolysis and subsequent disassembly.

Chemically Fuelled Self‐Regulating Gel‐to‐Gel Transition

“…EDC has been extensively used as fuel reaction for constructing transient hydrogel systems . However, in most of the cases, either a labile alcohol was added to form the metastable ester or a dicarboxylate was converted into cyclic anhydride . Important work in this area has been carried out by the groups of Boekhoven, Hartley and Das amongst others…”

Devising Synthetic Reaction Cycles for Dissipative Nonequilibrium Self‐Assembly

“…Recently, Das and co‐workers presented a chemically fueled system where an amphiphile (C18H) comprising of an eighteen‐carbon chain (C18) coupled to a histidine residue (H) was used as a substrate for esterification using 4‐nitrophenol (Figure 1f, Cat. 3) 52. This esterification step yielded a transient hydrogel that reverted back to soluble molecules upon ester hydrolysis, catalyzed by vicinal histidines.…”

“…Usually, the chemical fuels that have been used, are commonly available. More complex systems,48,51,52 require well‐designed building blocks and/or custom fuels, but they can express more sophisticated functions such as cooperative catalysis52 or membrane transport 48…”

“…(2) where the same chemistry (catalyzed or not) is responsible for all activation and/or deactivation steps;48–50 Cat. (3) where a catalyst exclusively acts on one specific step of the reaction cycle 51–54…”

Supramolecular Photothermal Effects: A Promising Mechanism for Efficient Thermal Conversion

“…Both the intramolecular de‐excitation and the intermolecular photophysical processes can be influenced. Furthermore, supramolecular systems can be composed of either a single component or multiple components, and the supramolecular structures can be either disordered, ordered or even hierarchical, showing a rich variety . As a consequence, supramolecular photothermal effects are much more complex and structure‐sensitive than molecular photothermal effects.…”