Article ; Online: Tetranuclear Copper(I) and Silver(I) Pyrazolate Adducts with 1,1′-Dimethyl-2,2’-bibenzimidazole
Molecules, Vol 28, Iss 1189, p
Influence of Structure on Photophysics
2023 Volume 1189
Abstract: A reaction of a cyclic trinuclear copper(I) or silver(I) pyrazolate complex ([MPz] 3 , M = Cu, Ag) with 1,1′-dimethyl-2,2’-bibenzimidazole ( L ) leads to the formation of tetranuclear adducts decorated by one or two molecules of a diimine ligand, ... ...
| Abstract | A reaction of a cyclic trinuclear copper(I) or silver(I) pyrazolate complex ([MPz] 3 , M = Cu, Ag) with 1,1′-dimethyl-2,2’-bibenzimidazole ( L ) leads to the formation of tetranuclear adducts decorated by one or two molecules of a diimine ligand, depending on the amount of the ligand added (0.75 or 1.5 equivalents). The coordination of two L molecules stabilizes the formation of a practically idealized tetrahedral four-metal core in the case of a copper-containing complex and a distorted tetrahedron in the case of a Ag analog. In contrast, complexes containing one molecule of diimine possess two types of metals, two- and three-coordinated, forming the significantly distorted central M 4 cores. The diimine ligands are twisted in these complexes with dihedral angles of ca. 50–60°. A TD-DFT analysis demonstrated the preference of a triplet state for the twisted 1,1′-dimethyl-2,2’-bibenzimidazole and a singlet state for the planar geometry. All obtained complexes demonstrated, in a solution, the blue fluorescence of the ligand-centered (LC) nature typical for free diimine. In contrast, a temperature decrease to 77 K stabilized the structure close to that observed in the solid state and activated the triplet states, leading to green phosphorescence at ca. 500 nm. The silver-containing complex Ag 4 Pz 4 L exhibited dual emission from both the singlet and triplet states, even at room temperature. |
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| Keywords | cyclic trinuclear complex ; pyrazolate adducts ; copper(I) ; silver(I) ; TD-DFT ; photoluminescence ; Organic chemistry ; QD241-441 |
| Subject code | 540 |
| Language | English |
| Publishing date | 2023-01-01T00:00:00Z |
| Publisher | MDPI AG |
| Document type | Article ; Online |
| Database | BASE - Bielefeld Academic Search Engine (life sciences selection) |
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