New molecular switch architectures

Abstract

In this paper we elaborate on recently developed molecular switch architectures and how these new systems can help with the realization of new functions and advancement of artificial molecular machines. Progress in chemically and photoinduced switches and motors is summarized and contextualized such that the reader may gain an appreciation for the novel tools that have come about in the past decade. Many of these systems offer distinct advantages over commonly employed switches, including improved fidelity, addressability, and robustness. Thus, this paper serves as a jumping-off point for researchers seeking new switching motifs for specific applications, or ones that address the limitations of presently available systems.

Hemithioindigos for Cellular Photopharmacology: Desymmetrised Molecular Switch Scaffolds Enabling Design Control over the Isomer‐Dependency of Potent Antimitotic Bioactivity

“…We believe that one factor behind this observation will prove to be that the relatively lipophilic HOTubs might be extensively localised in lipid environments (potentially with different partition coefficients in the Z and E forms), and that this modifies the effective cellular PSSs. While in the case of HOTub‐31 this may work in favour of the photoswitchability of its apparent potency, we anticipate that installing still better aqueous solubility in HTIs will prove important for their reliability in general cellular applications, for predictability of photoswitching and biodistribution as well as to avoid potential [2+2] photocycloadditions in aggregated HTIs (we also believe the importance of solubility is reflected in the weaker photoswitchability of potency of the nonhydroxylated HOTubs). Current advances in HTI photoswitch design are also leading to photoswitches with extremely high photoswitchability of isomer ratios, which if applied to HOTub derivatives could offer perspectives for even dark‐state‐active HTIs to be photopatterned with yet higher photoswitchability of bioactivity.…”

Recent Implementations of Molecular Photoswitches into Smart Materials and Biological Systems

“…The majority of described molecular photoswitches are based on the structure of AB, DAE, or SP. However, novel interesting scaffolds are continuously being reported …”

“…A brief description of photoisomerization mechanisms and significant recent applications for other important classes of molecular photoswitches, which are not discussed in detail in subsequent sections of this review, is provided below …”

Reversible Photoswitching of Isolated Ionic Hemiindigos with Visible Light

“…Many potential applications of photoswitches, particularly in biological contexts require them to respond within the biooptical window, prompting synthetic efforts aimed at shifting their absorptions to longer wavelength. [4][5][6][7][8][9] Recently, new classes of photoswitches such as DASAs, [10][11][12] hydrazones, [13,14] and indigoid chromophores [15][16][17][18][19] have been developed with strong absorptions in the red region of the spectrum, and with high photoisomerization quantum yields.Indigoid photoswitches such as hemithioindigo (HTI) [20][21][22][23] and hemiindigo (HI) [24][25][26] are chromophores derived from the parent indigo dye. [27] Although HI molecules were first synthesized over a century ago [24] and their basic photoswitching characteristics have been known for at least two decades, [25] interest has recently grown due to the development of new derivatives that respond to red light, have high thermal stability of their switching states, are simple to synthesize and function-alize, and exhibit high photostability.…”

“…Many potential applications of photoswitches, particularly in biological contexts require them to respond within the biooptical window, prompting synthetic efforts aimed at shifting their absorptions to longer wavelength. [4][5][6][7][8][9] Recently, new classes of photoswitches such as DASAs, [10][11][12] hydrazones, [13,14] and indigoid chromophores [15][16][17][18][19] have been developed with strong absorptions in the red region of the spectrum, and with high photoisomerization quantum yields.…”