Photoreversible Molecular Motion of stpyCN Coordinated to fac-[Re(CO)₃(NN)]⁺ Complexes

Abstract

In this work, efficient trans ⇌ cis photoswitchings of 4-(4-cyano)styrylpyridine (stpyCN) coordinated to organometallic bipyridyl tricarbonyl rhenium(I) complexes, fac-[Re(CO)(NN)( trans-stpyCN)], where NN = 2,2'-bipyridine (bpy) or 4,4'-dimethyl-2,2'-bipyridine (dmb), are described. For both complexes, the true trans-to- cis quantum yields determined by H NMR spectroscopy are similar at 313, 334, and 365 nm irradiations (Φ ∼ 0.45), with a small decrease at 404 nm (Φ ∼ 0.37). The investigated complexes also exhibit significant quantum yields for the reversible cis-to- trans photoreactions (Φ = 0.22). The luminescent properties of these complexes were also analyzed in different media to elucidate a key role of the IL state in photophysical and photochemical processes, giving new insights on their intriguing photobehavior.

Spectroscopic Study of the E/Z Photoisomerization of a New Cyrhetrenyl Acylhydrazone: A Potential Photoswitch and Photosensitizer†

“…In addition, the quantum yield (Φ E ‐CyAH → Z ‐CyAH ) of this photoisomerization process under UV irradiation was calculated to be 0.30 (Figs. and ), which is similar to those values reported in the literature for fac ‐[Re(CO) 3 (NN)L] + complexes, where NN = bpy, phen, and L = stpyCN, bpe (29,31,33).…”

“…The singlet MLCT excited state ( 1 MLCT) undergoes a fast intersystem crossing to the triplet excited state ( 3 MLCT) (27), which can transfer its energy to a triplet intraligand excited state ( 3 IL) localized on the photoswitchable fragment, finally producing a photoisomerization reaction (28). For example, fac-tricarbonyl Re(I) fragments have been used to promote the photoisomerization of stilbene-like and azobenzene ligands in the visible spectral region (29)(30)(31)(32)(33)(34). These compounds showed a remarkable cis ⇌ trans photoreversibility with quantum yield values as high as Φ trans?cis = 0.17-0.65 range and Φ cis?trans = 0.16-0.26 range, offering a new strategic approach to designing molecular switches (32,33).…”

Insights into the Effect of Trans-to-Cis Photoisomerization of a Co-coordinated Stilbene Derivative on the Luminescence of Di-β-diketonate Lanthanide Complexes

“…Table shows the trans-to-cis quantum yields (Φ t–c ) under irradiation at 312 nm and photoisomerization rate constants ( k , s –1 ) of HL and complexes 1 – 5 in acetonitrile (UV light power, 266 μW cm –2 at 312 nm). Although nuclear magnetic resonance (NMR) spectroscopy can be used to obtain an accurate quantum yield, , the quantum yields herein, calculated using only the UV–vis spectrum variations, were “apparent”. These calculations were performed using the same method as in our previous report .…”

Low-cost photo-switches based on stilbene-appended Zn(II)–terpyridine complexes

“…Optically stimulated reversible trans-cis isomerization of stilbene appended heavier transition metal complexes (particularly Re, Ru, Ir and Pt) were thoroughly investigated by different research groups [46][47][48][49][50][51][52][53][54][55][56]. The results of these investigations laid the foundation for the construction of effective photo molecular switches.…”