Excited-State Dynamics of Structurally Characterized [Re^I(CO)₃(phen)(HisX)]⁺ (X = 83, 109) Pseudomonas a eruginosa Azurins in Aqueous Solution

Abstract

The triplet metal-to-ligand charge transfer ((3)MLCT) dynamics of two structurally characterized Re(I)(CO)(3)(phen)(HisX)-modified (phen = 1,10-phenanthroline; X = 83, 109) Pseudomonas aeruginosa azurins have been investigated by picosecond time-resolved infrared (TRIR) spectroscopy in aqueous (D(2)O) solution. The (3)MLCT relaxation dynamics exhibited by the two Re(I)-azurins are very different from those of the sensitizer [Re(I)(CO)(3)(phen)(im)](+) (im = imidazole). Whereas the Re(I)(CO)(3) intramolecular vibrational relaxation in Re(I)(CO)(3)(phen)(HisX)Az (4 ps) is similar to that of [Re(I)(CO)(3)(phen)(im)](+) (2 ps), the medium relaxation is much slower ( approximately 250 vs 9.5 ps); the 250-ps relaxation is attributable to reorientation of D(2)O molecules as well as structural reorganization of the rhenium chromophore and nearby polar amino acids in each of the modified proteins.

Ultrafast Excited State Dynamics Controlling Photochemical Isomerization of N‐Methyl‐4‐[trans‐2‐(4‐pyridyl)ethenyl]pyridinium Coordinated to a {ReI(CO)3(2,2′‐bipyridine)} Chromophore

“…[1][2][3][4]25] As their detailed excitedstate characters are very sensitive to the medium, Re I complexes can serve as probes of the character and dynamics of the chromophore environment, which can be varied from simple solvents to polymers or protein binding sites. [4,10] Optical excitation of the {Re I (CO) 3 A C H T U N G T R E N N U N G (N,N)} chromophore into an MLCT excited state redistributes the electron density to {Re II (CO) 3 A C H T U N G T R E N N U N G (N,NC À )}. In response, the axial ligand X can perform various chemical functions, depending on whether it is an electron donor, electron acceptor, or an energy acceptor.…”

Relativistic effects in spectroscopy and photophysics of heavy-metal complexes illustrated by spin–orbit calculations of [Re(imidazole)(CO)3(phen)]+

“…It will be demonstrated that the SO model accounts very well for absorption spectra, emission properties, and excited-state dynamics, some of its conclusions being qualitatively different from the spinfree approach. [Re(imH)(CO) 3 (phen)] + represents a broad class of Re I tricarbonyl-diimine complexes [21][22][23], which show very rich photophysics and photochemistry [10,14,15,24] and engage in a range of photonic applications such as photosensitizers and phototriggers of electron-transfer reactions [11,[25][26][27][28][29], photocatalysts of CO 2 reduction [30][31][32], phosphorescent labels and probes of biomolecules [33][34][35][36], sensors [37,38], molecular switches [39][40][41][42] and OLED emitters [43], or probes of ps-ns dynamics of solvents, proteins or supramolecular hosts [11,24,50,51,[63][64][65]. The chosen example [Re(imH)(CO) 3 (phen)] + [44] not only epitomizes the salient features of Re I carbonyl-diimine photophysics but also has a prominent position amongst Re-based photosensitizers because of its ability to trigger photoinduced electron transfer and relaxation dynamics in Re-labeled proteins [11,25,[44]…”

Exploitation of Luminescent Organometallic Rhenium(I) and Iridium(III) Complexes in Biological Studies

“…Remarkably, when the copper(I) oxidation rates are plotted against Cu-surface histidine distances, an excellent agreement with those predicted based on the standard distance-decay constant b of 1.1 Å −1 is observed, concluding the involvement of the metal-coordinated histidine in the electrontransfer. In another study, the 3 MLCT relaxation dynamics displayed by two structurally characterised mutants [Re(phen)(CO) 3 (HisX)]-Az (X = 83, 109) in D 2 O have been examined by picosecond time-resolved infrared spectroscopy [31]. A much slower medium relaxation has been ascribed to the reorientation of the solvent molecule and the structural reorganisation of the rhenium complex and the nearby polar amino acid residues.…”