ChemInform Abstract: Ligand‐Dependent Excited State Behavior of Re(I) and Ru(II) Carbonyl—Diimine Complexes

Abstract

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Re(I) tricarbonyl complex of 1,10-phenanthroline-5,6-dione: DNA binding, cytotoxicity, anti-inflammatory and anti-coagulant effects towards platelet activating factor

“…The UV bands resemble in shape and position the lowest-energy ones in the corresponding spectrum of the free diimine ligand, despite they are found at higher wavelengths and are more structured. The shape along with the position and the solvent dependence of the low-energy band denote its (Re)dπ→π*(phendione) chargetransfer (MLCT) character, which agrees with previous interpretations of many mononuclear tricarbonyl Re complexes [41,42]. From Fig.…”

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]…”

“…2 and 3. Regardless the spin, the spectroscopically and photophysically relevant low-lying excited states of Re I tricarbonyl diimines [Re(L)(CO) 3 (N ∧ N)] n result from mixing of MLCT, LLCT, and IL characters [21,22], whose extent determines the excited-state properties. Two types of mixing have to be considered: (i) MLCT-LLCT mixing.…”

“…Mixing of MLCT and L → N ∧ N LLCT characters is especially strong in complexes containing donating ligand L (halides, NCS − , amides, phosphides, alkoxides, thiolates, imidazole, etc.) [9][10][11][12][13]21,22,60,61]. For example, the low-lying excited-states of [Re(I)(CO) 3 (bpy)] contain about 50% of I → bpy LLCT and 50% Re(CO) 3 → bpy MLCT characters [10] and are best viewed as delocalized Re(I)(CO) 3 → bpy CT. Mixing between metal d and ligand (L) p orbitals is well described (sometimes even exaggerated) by DFT with hybrid functionals [8,9,13,62], which calculates the lowest two MLCT/LLCT transitions as occurring from occupied (d-p) Kohn-Sham molecular orbitals, which are -antibonding with respect to the M-L bond, to a *(N ∧ N) orbital.…”

Spectroscopic characterization of chloride and pseudohalide ruthenium(II) complexes with 4-(4-nitrobenzyl)pyridine

“…On the one hand, N-heterocyclic pacceptor ligands determine the character of the unoccupied LUMO orbital. On the other hand, it is known that pseudohalide ligands tune the t 2g ruthenium orbitals by distributing the 4d Ru energy levels over a wide energy range, due to mixing with orbitals centered on the thiocyanate (NCS) ligand [15][16][17]. Thus, studies of the electronic structures of these complexes are an important area of chemistry.…”