Investigating the Effects of Solvent on the Ultrafast Dynamics of a Photoreversible Ruthenium Sulfoxide Complex

Abstract

The photochromic complex [Ru(bpy)2(pySO)](2+) [pySO is 2-(isopropylsulfinylmethyl)pyridine] undergoes wavelength specific, photoreversible S → O and O → S linkage isomerizations. Irradiation of the ground state S-bonded complex with blue light produces the O-bonded isomer, while irradiation of the O-bonded isomer with green light produces the S-bonded isomer. Furthermore, isomerization time constants are solvent-dependent. Ultrafast transient absorption spectroscopy has been employed to investigate the relaxation processes that lead to S → O isomerization in 1,2-dichloroethane, propylene carbonate, and ethylene glycol. The isomerization is most rapid in 1,2-dichloroethane and slowest in ethylene glycol. Photochemical reversion of the O-bonded isomer in propylene carbonate has further been investigated and indicates similar relaxation or isomerization kinetics, though the excited states that lead to isomerization are distinct between the S- and O-bonded isomers.

Establishing the Two-Photon Linkage Isomerization Mechanism in the Nitrosyl Complex trans-[RuCl(NO)(py)4]2+ by DFT and TDDFT

“…It is worth noticing that, in contrast with polypyridyl ruthenium complexes, no triplet metal-centered states ( 3 MC) have been identified for this system on the lowest triplet PES. 43,45,73,74 The lowest triplet state minima have been compared with their parent singlet geometries (Table 1) This key step is observed with the population of 3 MS2, whose geometry perfectly reflects this inversion (Table 1). From a structural point of view, it seems more favorable to go from one triplet to the other, rather than from one singlet to the other, because the changes in the Ru−N−O angles in the triplet state are smaller.…”

New RuII Complex for Dual Activity: Photoinduced Ligand Release and 1O2 Production

“…The wide use of Ru II polypyridyl complexes for applications that include photochemotherapy (PCT), solar energy conversion, sensors, and molecular switches stems from their strong absorption throughout the ultraviolet and visible regions that arise from ligand‐centered 1 ππ* and metal‐to‐ligand charge transfer ( 1 MLCT) transitions, together with 3 MLCT excited states that are long‐lived, emissive, and redox‐active . In addition to regenerating the ground state directly, the deactivation of the 3 MLCT states can occur by population of low‐lying excited states, such as non‐emissive triplet ligand field ( 3 LF) or ligand‐centered 3 ππ* states .…”

“…Complex 1 represents am odel compound for dual activity that may be appliedt ophotochemotherapy.The wide use of Ru II polypyridyl complexes for applications that include photochemotherapy( PCT), solar energy conversion, sensors, and molecular switches stemsf rom their strong absorption throughout the ultraviolet and visible regions that arise from ligand-centered 1 pp*a nd metal-to-ligand charge transfer ( 1 MLCT) transitions, together with 3 MLCT excited states that are long-lived,e missive, and redox-active. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In addition to regeneratingt he ground state directly,t he deactivation of the 3 MLCT states can occur by population of low-lyinge xcited states, such as non-emissive triplet ligand field ( 3 LF) or ligandcentered 3 pp*s tates. [17,18] The ability to control the relative populations of such excited states is useful for the design of metal complexes to undergo specific desired processes, such as ligand dissociation and the generation of 1 O 2 .…”

“…The irradiation of [Ru(bpy)(dppn)(CH 3 CN) 2 ] 2 + with visible light results in the exchange of the CH 3 CN ligands with F 400 = 0.002(3) for the first step in H 2 O; however,t he lowest excited state is dppn 3 pp*i n nature,s ot he complex also produces 1 O 2 with F D = 0.72(2) in CH 3 OH. [33] This strategy was also applied in the case of [Ru-(tpy)(Me 2 dppn)(py)] 2 + (Me 2 dppn = 3,6-dimethylbenzo[i]dipyrido[3,2-a:2',3'-c]phenazine) to effect py dissociation, F 500 = 0.053(1) in CH 3 CN, in conjunction with 1 O 2 production, F D = 0.69 (9) in CH 3 OH. [34] Herein we report the new photoactive complex [Ru-…”

New Ru(II) Complexes for Dual Photoreactivity: Ligand Exchange and 1O2 Generation

“…Excited states of Ru(II) complexes have been used in solar energy conversion, 1–5 in charge transfer reactions, 6,7 as sensors and switches, 8,9 and as potential therapeutic agents in photochemotherapy (PCT) and imaging. 10–16 Although many complexes are derived from [Ru(bpy) 3 ] 2+ (bpy = 2,2′-bipyridine) (Figure 1a), 17 these applications often have different demands.…”