Bossi, Alberto and Rausch, Andreas F. and Leitl, Markus J. and Czerwieniec, Rafal and Whited, Matthew T. and Djurovich, Peter I. and Yersin, Hartmut and Thompson, Mark E. (2013) Photophysical Properties of Cyclometalated Pt(II) Complexes: Counterintuitive Blue Shift in Emission with an Expanded Ligand pi System. INORGANIC CHEMISTRY, 52 (21). pp. 12403-12415. ISSN 0020-1669, 1520-510X
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A detailed examination was performed on photophysical properties of phosphorescent cyclometalated (C<^>N)Pt-(O<^>O) complexes (ppy)Pt(dam) (1), (ppy)Pt(acac) (1'), and (bzq)Pt(dpm) (2) and newly synthesized (dbq)Pt(dpm) (3) (C<^>N = 2-phenylpyridine (ppy), benzo[h]quinoline (bzq), dibenzo[f,h]quinoline (dbq); O<^>O = dipivolylmethanoate (dpm), acetylacetonate (acac)). Compounds 1, 1', 2, and 3 were further characterized by single crystal X-ray diffraction. Structural changes brought about by cyclometalation were determined by comparison with X-ray data from model C<^>N ligand precursors. The compounds emit from metal-perturbed, ligand-centered triplet states (E0-0 = 479 nm, 1; E0-0 = 495 nm, 2; E0-0 = 470 nm, 3) with disparate radiative rate constants (k(r) = 1.4 x 10(5) s(-1), 1; k(r) = 0.10 x 10(5) s(-1), 2; k(r) = 2.6 x 10(5) s(-1), 3). Zero-field splittings of the triplet states (Delta EIII-I = 11.5 cm(-1), 1'; Delta EIII-I < 2 cm(-1), 2; Delta EIII-I = 46.5 cm(-1), 3) were determined using high resolution spectra recorded in Shpol'skii matrices. The fact that the E0-0 energies do not correspond to the extent of pi-conjugation in the aromatic C<^>N ligand is rationalized on the basis of structural distortions that occur upon cyclometalation using data from single crystal X-ray analyses of the complexes and ligand precursors along with the triplet state properties evaluated using theoretical calculations. The wide variation in the radiative rate constants and zero-field splittings is also explained on the basis of how changes in the electronic spin density in the C<^>N ligands in the triplet state alter the spin-orbit coupling in the complexes.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | LOCALIZED (3)PI-PI(ASTERISK) STATE; TRANSFER EXCITED-STATES; ENERGY-GAP LAW; CHARGE-TRANSFER; TRIPLET-STATE; PLATINUM(II) COMPLEXES; TEMPERATURE-DEPENDENCE; IRIDIUM COMPLEXES; ELECTROCHEMICAL PROPERTIES; PHOSPHORESCENCE SPECTRA; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) > Prof. Dr. Hartmut Yersin |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 25 Mar 2020 12:19 |
| Last Modified: | 25 Mar 2020 12:19 |
| URI: | https://pred.uni-regensburg.de/id/eprint/15687 |
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