Redox‐Mediated Transient Reconfiguration of a Supramolecular Assembly

Abstract

Dissipative systems, that constantly consume energy for sustenance, are ubiquitous and essential to life. In synthetic systems, the phenomenon promises emergent properties and different structure from the ones existing at thermodynamic equilibrium. It can create reconfigurable and temporally programmable life-like smart materials. In this study, we attempt to create reconfigurable, temporally programmable self-assembly using the redox chemistry of a core-substituted naphthalene diimide derivative. As a result, transient reconfiguration of supramolecular assembly from vesicle to sheet along with transient fluorescence switching with fuel-dependent lifetime is attained. We believe that such a design strategy can advance the synthesis of active, adaptive and autonomous materials.Self-(re)organization, i. e. spatiotemporal ordering is a common phenomenon observed in nature. [1] Cytoskeletal elements, organelles and cells undergo reorganization into different sizes, shapes and composition during the phases of cell division and this reconfiguration facilitates the various functional processes. [2] Nature accomplishes this spatiotemporal control by dissipative self-assembly. [3] In recent years, the adaptation of this in synthetic systems by utilizing chemical fuels, [4] light, [5] enzyme, [6] redox [7] etc. have resulted in unprecedented temporally programmed structures and transient properties such as gelation [8] and ink [5a,9] and functions such as ion-transport, [10] catalysis [11] and photonics. [12] Until now, dissipative self-assembly with assembled transient states has been reported. [13] The current challenge is to move a step further to create self-(re) organization or reconfiguration of self-assembly with temporal regulation. This can result in emergent properties distinguishable from the materials obtained at equilibrium.Amongst various synthetic designs for transient materials, redox-fueled approach stands out due to its applicability in a plethora of chromophoric, charge-transfer and disulfide based molecular systems. Hermans and co-workers applied redox chemistry to attain oscillations in the self-assembly of perylene bisimide chromophores. [14] Thordarson [7b] and Besenius [7c] independently utilized redox activity of sulfide and thioether functional groups, respectively to obtain transient self-assembly. Our group has shown a transient conformational switching [7a] in amphiphilic self-assembly of a charge-transfer foldamer by coupling the reducing agent to enzymatic oxidation by glucose oxidase. These reports display the importance of redox chemistry to create transient self-assembly. In this report, we extend this redox strategy to go from naive transient selfassembly to transient reconfiguration of supramolecular nanostructures.In this study, we address one of the challenges to visualize/ probe the temporal changes during the transient cycle. Coresubstituted naphthalene diimide [15] (cNDIs) are the class of chromophores with distinct absorption and emission features, sensitive to the molecul...

Transient DNA‐Based Nanostructures Controlled by Redox Inputs

“…Similar examples have been also reported for the synthesis of dissipative supramolecular assemblies driven by chemical‐reaction cycles, including redox reactions . In our case, the versatility of DNA‐based assembly and the predictability of the involved interactions offer the possibility to kinetically control both assembly and disassembly of the nanostructures and to finely control their lifetime in a way that would be difficult to achieve with other synthetic approaches.…”

“…Similar examples have been also reported for the synthesis of dissipative supramolecular assemblies driven by chemical-reaction cycles, [21,23,55] including redox reactions. [55][56][57][58][59][60][61] In our case,the versatility of DNA-based assembly and the predictability of the involved interactions offer the possibility to kinetically control both assembly and disassembly of the nanostructures and to finely control their lifetime in aw ay that would be difficult to achieve with other synthetic approaches.O ur strategy is in fact solely based on redox cycles of reduction/oxidation of disulfide DNAstrands acting as regulators for the assembly or disassembly of DNA-based tubular structures that, once reduced, loose their regulation functionality and allow the system to return to its native resting state.T he same approach could be conveniently employed to more complex DNAo rigami [62,63] or to achieve transient structural reconfiguration of DNAstructures. [39] As redox oscillations in cells control many biochemical pathways it would also be of great interest to show similar behaviour in synthetic DNAs ystems.…”

The Transient Covalent Bond in Abiotic Nonequilibrium Systems

“…through the interconversion of thiols and disulfides.S pecific examples can be classified as either Ty pe 1or2depending on their details.W en ote also that several systems have been reported that apply redox fuels to the reduction of perylene [49,50] and naphthalene diimides [51] that operate by modulating noncovalent interactions.…”

Accelerated Ripening in Chemically Fueled Emulsions**

“…However, these theoretical predictions lack experimental systems to test them quantitively. Examples of synthetic molecular assemblies regulated by fuel‐driven reaction cycles have been described, including chemically [17–25] and photo‐chemically fueled fibers, [17,18,23,26] dynamic vesicles formed by the consumption of ATP, [27] dynamic DNA‐based assemblies, [28] colloids [29–32] and others [33,34] . Indeed, such studies result in surprising behavior like dynamic instabilities in synthetic fibers [19] or solutions of nanostructures that oscillate between different colors [35] .…”