Photochromic Hydrazone Switches with Extremely Long Thermal Half-Lives

Abstract

A family of easily accessible light-activated hydrazone switches has been developed having thermal half-lives of up to 2700 years! Structure-property analysis shows that replacing the rotor pyridyl group of our typical hydrazone switch with a phenyl one leads to the long-lived negative photochromic compounds. The switching properties of the hydrazones in both toluene and DMSO were assessed offering insights into the kinetics and thermodynamics of the switching process.

Acylhydrazone Switches: E/Z Stability Reversed by Introduction of Hydrogen Bonds

“…[9] This has been partially realized in some examples that have enabled the use of pH or metal ions as a stimulus, [10] with some of these designs being integrated as core components of molecular robots. [14] While the above examples open up the prospect of using hydrogen bonding to regulate hydrogen bond basicity scales ( and DN) of the solvent. [12,13] Aprahamian has reported one kind of hydrazone in which the Z isomer is thermodynamically more stable than its E isomer as a result of favorable hydrogen bonds and the avoidance of steric hindrance.…”

“…[12,13] Aprahamian has reported one kind of hydrazone in which the Z isomer is thermodynamically more stable than its E isomer as a result of favorable hydrogen bonds and the avoidance of steric hindrance. [14] While the above examples open up the prospect of using hydrogen bonding to regulate hydrogen bond basicity scales ( and DN) of the solvent. This solvent effect was also found to be relative to the skeleton of compound, the less shield of hydrogen bond domain the more sensitivity to the solvent environment.…”

Nanoscale Chemical Imaging of Reversible Photoisomerization of an Azobenzene‐Thiol Self‐Assembled Monolayer by Tip‐Enhanced Raman Spectroscopy

“…[1][2][3][4] Of the various molecular switches studied, azobenzene and its derivatives adsorbed on surfaces,one of the most thoroughly investigated classes of molecular switches, [5][6][7] have attracted considerable attention in the last few years thanks to their practical applications as nanomotors, [8] in adaptive imaging, [9] and as energy storage devices [10] when binding to adaptive surfaces.T he photoisomerization of azobenzene can be triggered by illumination at the appropriate wavelength. [1][2][3][4] Of the various molecular switches studied, azobenzene and its derivatives adsorbed on surfaces,one of the most thoroughly investigated classes of molecular switches, [5][6][7] have attracted considerable attention in the last few years thanks to their practical applications as nanomotors, [8] in adaptive imaging, [9] and as energy storage devices [10] when binding to adaptive surfaces.T he photoisomerization of azobenzene can be triggered by illumination at the appropriate wavelength.…”

Nanoscale Chemical Imaging of Reversible Photoisomerization of an Azobenzene‐Thiol Self‐Assembled Monolayer by Tip‐Enhanced Raman Spectroscopy

“…Molecular switches,which undergo molecular-scale motion upon external stimuli, are very promising for molecular electronics and high-density data storage.However,adeeper understanding of their mechanical and electronic properties at the molecular level is required for developing applications in the areas of information processing, energy,and biology. [1][2][3][4] Of the various molecular switches studied, azobenzene and its derivatives adsorbed on surfaces,one of the most thoroughly investigated classes of molecular switches, [5][6][7] have attracted considerable attention in the last few years thanks to their practical applications as nanomotors, [8] in adaptive imaging, [9] and as energy storage devices [10] when binding to adaptive surfaces.T he photoisomerization of azobenzene can be triggered by illumination at the appropriate wavelength. Azobenzene undergoes trans-to-cis isomerization when irradiated with ultraviolet (UV) light (365 nm).…”