Redox-Dependent Conformational Switching of Diphenylacetylenes

Abstract

Herein we describe the design and synthesis of a redox-dependent single-molecule switch. Appending a ferrocene unit to a diphenylacetylene scaffold gives a redox-sensitive handle, which undergoes reversible one-electron oxidation, as demonstrated by cyclic voltammetry analysis. 1 H-NMR spectroscopy of the partially oxidized switch and control compounds suggests that oxidation to the ferrocenium cation induces a change in hydrogen bonding interactions that results in a conformational switch.

Ion-mediated conformational switches

“…Molecular switches have subsequently been developed based upon the diphenylacetylene platform that are responsive to stimuli including Lewis and Brønsted acids, Brønsted bases and changes in redox potential. 4 , 54 , 55 …”

“…While peptidic systems typically involve the complex interplay of a large number of stabilizing interactions, the bottom-up approach of a synthetic chemist allows tuning of architecturally minimal designs to provide an output in response to a specific stimulus. The last decade has seen an explosion of interest in this area with the development of switches responsive to light, 2 , 3 redox processes, 4 and the focus of this Perspective – ions. Potential applications of molecular switches include bio-imaging, 5 drug delivery, 6 organic light-emitting diodes, 7 molecular electronics, 8 catalysis, 9 and receptors for use in a range of settings.…”

Tuning Aqueous Supramolecular Polymerization by an Acid‐Responsive Conformational Switch

“…Subtle conformational changes of biomacromolecules, triggered by physiological stimuli, regulate various complex biological events, such as protein folding and membrane transport . Chemists have long sought to replicate these phenomena by synthesizing artificial molecular switches and machines that show switching between two conformational states in response to external stimuli, such as light, redox, pH, or cation/anions . In recent years, different types of molecular switches derived from diarylethenes, spiropyrans, spirooxazines, fulgides, and flavylium have been widely explored, with some promising applications in bioimaging, drug delivery, organic light‐emitting diodes, molecular electronics and catalysis .…”

Modulation of Conformational Preferences of Heteroaromatic Ethers and Amides through Protonation and Ionization: Charge Effect

“…For example, the pH‐triggered conformational switch of heteroaromatic lipids can control the channels on membrane . The ionization/oxidation‐induced conformational switching of some aromatic compounds is also found . If the protonation or ionization can modulate the conformation of heteroaromatics, the heterocyclic hinges can operate by pH or redox.…”

“…[17] The ionization/oxidation-induced conformational switching of some aromatic compounds is also found. [18,19] If the protonation or ionization can modulate the conformation of heteroaromatics, the heterocyclic hinges can operate by pH or redox. Since both the protonation and ionization introduce one positive charge into the molecule, the effect of the positive charge on stability of molecular conformers will provide information helpful for understanding the origin of conformational preferences.…”