Ligand Influence on the Photophysical Properties and Electronic Structures of Tungsten Iodide Clusters

Abstract

Compounds containing the [Mo6I8L6]2– ion in which L is an inorganic or organic ligand show remarkable photophysical properties. Similar properties were observed for the corresponding compounds based on octahedral tungsten clusters. The properties of these photosensitizers are significantly impacted by the six outer iodide ligands of [W6I8I6]2–. To analyze the role of the outer ligands, we prepared and structurally characterized octahedral tungsten cluster compounds with [W6I8I6]2– and [M6I8L6]2– ions (M = W, Mo; L = para‐toluenesulfonate). The distinct photophysical properties of the clusters were analyzed with respect to their photoluminescence (i.e., phosphorescence) and luminescence quenching in the presence of molecular oxygen. The electronic structures were analyzed through photoelectron spectroscopy to expose differences in the electronic situations of the compounds.

Alkaline Earth Cluster Compounds AE[W6I14] and the Solvate [Ca(C2H6SO)6][W6I14]

“…( n Bu 4 N) 2 [W 6 I 14 ] and other compounds based on the [W 6 I 14 ] 2– clusters represent prominent materials for optical properties (luminescence, singlet oxygen production) , . Alkali compounds A 2 [W 6 I 14 ] have shown poor luminescence properties in solid state, due to their dark body colors , .…”

“…Compounds were used as purchased without any further purification: WCl 6 (Acros Organic, 99.9+ %), SiI 4 [20] The reaction of 50 mg (0.013 mmol) W 6 I 22 and (AE)I (50 mmol) was carried out in acetone solution (50 mL) under air. After one day of stirring, the product can be obtained as a precipitated dark Z. Anorg.…”

“…This compound can be then utilized in the preparation of ligand exchanged clusters, such as (nBu 4 N) 2 [W 6 I 8 (O 3 S 2 C 7 H 7 ) 6 ], which are showing enhanced luminescence properties including high singlet oxygen quantum yields. [4][5][6][7][8][9][10][11] These compounds have possible applications as oxygen sensors [12,13] , in the photodynamic therapy and bioimaging. [14][15][16] A 2 [W 6 I 14 ] compounds with A = alkaline metal are usually obtained from solid-state reactions of mixtures of a binary iodide (e.g.…”

Molybdenum Iodides – from Obscurity to Bright Luminescence

“…These compounds show strong long‐lived luminescence and significant quenching by O 2 in the solid state and in solution. The electronic structures reveal decrease in the HOMO and LUMO energy levels following the order [W 6 I 14 ] 2– > [{W 6 I 8 }(OTs) 6 ] 2– > [{Mo 6 I 8 }(OTs) 6 ] 2– , , . The lability of tosylate in (Bu 4 N) 2 [{M 6 I 8 }(OTs) 6 ] is such that it can be substituted with solvent molecules (100° C, 14.5 h, with the formation of [M 6 I 8 (pts) 6‐x (CH 3 CN) x ] –(2–x) (x = 1–2) and [M 6 I 8 (pts) 6‐x ((CD 3 ) 2 SO) x ] –(2–x) (x = 4–6), respectively.…”

Solid‐State Phosphorescence of A2[W6I14] with A = PPN, PPh4

“…Photoluminescence studies on crystalline (TBA) 2 [W 6 I 14 ] (TBA = tetrabutylammonium) have shown the absence of a significant phosphorescence quenching, revealing the absence of an energy transfer from the iodide cluster onto atmospheric O 2 in solid state . The same behavior is evidenced for M = Mo .…”