Computational and Crystallographic Examination of Naphthoquinone Based Diarylethene Photochromes

Abstract

Photochromic compounds have a lengthy history of study and a profusion of applications that stand to gain from these studies. Among the classes of photochromic compounds, diarylethenes show desirable properties including high fatigue resistance and thermal stability, thus meeting some of the most important criteria necessary to enter the realm of practical applications. Recently, photochromic diarylethenes containing quinone functionalities have demonstrated interesting optical and solid-state properties. When properly interfaced with suitable electron withdrawing groups on the aryl component, both the ring-opening and ring-closing reactions can be achieved with visible light; this is in contrast to most other diarylethenes where UV light is required for ring closure. Unfortunately, quantitative conversion from open to closed forms is not possible. In this work, we examine the relative energies of conformations of solid-state structures observed by X-ray crystallography and evaluate their thermal stabilities based on density functional theory (DFT) calculations. Time-dependent DFT (TD–DFT) is used to model the UV-vis absorption spectra of these quinone diarylethenes. We show that spectral overlap between open and closed forms is a major hindrance to full photoconversion.

Future‐Oriented Advanced Diarylethene Photoswitches: From Molecular Design to Spontaneous Assembly Systems

“…Given the differences in the structure of DAE in its solid phase and free state, [ 80 ] the self‐assembly process, which expands the application range of DAEs as a stimulus‐responsive tool, raises intermolecular interactions to an important position that should be considered. In their aggregate or solid state, DAE molecules engage in self‐assembly behavior that produces a relatively ordered nanostructure.…”

Crystallographic, spectroscopic, and computational characterization of a diiodonaphthoquinone diarylethene photochrome: halogen bonding and photocrystallography

“…A solution of the ring-closed isomer of 2,3-bis(2,5-dimethylthiophen-3yl)-5,6-dimethyl-1,4-benzoquinone exhibited no ring-opening isomerization when left for 14 days in the dark at room temperature 34 indicating its thermal stability. In solution photochemical, ring closure of dithienyl quinone and naphthoquinone containing DAEs is known to proceed with efficiencies less 18,19,34 than that of the better known and structurally related perfluorocyclopentene containing DAEs. 35 However, chemically induced ring closure can be achieved in high yield when three equivalents of AlCl 3 in methylene chloride are added to the quinone and naphthoquinone containing ring-open isomers.…”

“…15–17 It has been demonstrated that the use of either a quinone or naphthoquinone ethene bridge allows for visible light to initiate photoisomerization in both the ring-opening and ring-closing directions. 18–20 Quinone based headgroups are also electrochemically active 21,22 and found in important biological molecules, 23,24 thus making them excellent candidates for potential therapeutic agents. 25…”

“…[15][16][17] It has been demonstrated that the use of either a quinone or naphthoquinone ethene bridge allows for visible light to initiate photoisomerization in both the ringopening and ring-closing directions. [18][19][20] Quinone based headgroups are also electrochemically active 21,22 and found in important biological molecules, 23,24 thus making them excellent candidates for potential therapeutic agents. 25 The rational design of DAE-based crystalline materials remains challenging and is due in part to the conformational flexibility associated with the free rotation of the aryl groups responsible for the photoactivity.…”