Synthesis, Photophysical, Photochemical, and Redox Properties of Nitrospiropyrans Substituted with Ru or Os Tris(bipyridine) Complexes

Abstract

Photochromic nitrospiropyrans substituted with 2,2′-bipyridine (bpy), [Ru(bpy) , resulting in energy transfer from the excited ruthenium center to the spiropyran but inversely in the osmium case. The open merocyanine form reduces and oxidizes electrochemically more easily than the closed nitrospiropyran. Like photoexcitation, electrochemical activation also causes opening of the spiropyran ring by first reducing the closed form and subsequently reoxidizing the corresponding radical anion in two wellresolved anodic steps. Interestingly, the substitution of the spiropyran with a Ru or Os metal center does not affect the efficiency of this electrochemically induced ring-opening process, different from the photochemical path.

(Polypyridyl)ruthenium(II) Complexes Based on a Back‐to‐Back Bis(pyrazolylpyridine) Bridging Ligand

“…Additionally, electrospray ionisation time-of-flight (ESI-TOF) measurements were applied to the PF 6 4+ at m/z = 291.54. In general, ESI-TOF leaves the molecular ions of the complexes relatively intact (see also Supporting Information).…”

“…[1,2] Light-absorbing and light-emitting properties of ruthenium complexes elevate them to the ranks of prominent candidates for applications dealing with light-driven conversion processes such as, e.g., artificial photosynthesis, [3] photocatalytic production of hydrogen, [4] vectorially controlled energy transfer, [5] photoactivated reactions, [6] dye-sensitised solar cells, [7] photomolecular switches, [8] as well as ion-specific sensing systems, [9] and other related molecular devices. [10] Oligonuclear ruthenium complexes are frequently used to enhance photochemical and photophysical properties of photoactive systems by antenna-like light-harvesting.…”

Hemithioindigo—an emerging photoswitch

“…in hexane [20] 4: stable (lifetime close-4: R 1 = Me, R 2 = H close-5: R 1 = H, R 2 = Me longer than 12 h at 80°C) [23] spiropyran spiropyran-6 298 (8,570) in ethanol [24] 100% merocyanin (334 nm in THF) [25] φ Sp = 0.15 in ethanol [24] τ = 67 (λ exc = 630 nm), 36 (λ exc = 490 nm) in toluene [26] merocyanin-6 537 (36,800) in ethanol [24] φ Mc = 0.04 in ethanol [24] ∆G* = 22 in DMSO [27] …”

Photochromic Molecules as Building Blocks for Molecular Electronics

“…Meanwhile we have constructed a series of molecular devices with incorporated photochromic switches, showing interesting photophysical properties. [9] Molecular Electronics in Selfassembled Monolayers (SAM)…”