Hofbeck, Thomas and Lam, Yan Choi and Kalbac, Martin and Zalis, Stanislav and Vlcek, Antonin and Yersin, Hartmut (2016) Thermally Tunable Dual Emission of the d(8)-d(8) Dimer [Pt-2(mu-P2O5(BF2)(2))(4)](4-). INORGANIC CHEMISTRY, 55 (5). pp. 2441-2449. ISSN 0020-1669, 1520-510X
Full text not available from this repository. (Request a copy)Abstract
High-resolution fluorescence, phosphorescence, as well as related excitation spectra, and, in particular, the emission decay behavior of solid [Bu4N](4)[Pt-2(mu-P2O5(BF2)(2))(4)], abbreviated Pt(pop-BF2), have been investigated over a wide temperature range, 1.3-310 K. We focus on the lowest excited states that result from d sigma*p sigma (Sd(z)(2)-6p(z)) excitations, i.e., the singlet state S-1 (of (1)A(2u) symmetry in D-4h) and the lowest triplet T-1, which splits into spin-orbit substates A(1u)((3)A(2u)) and E-u((3)A(2u)). After optical excitation, an unusually slow intersystem crossing (ISC) is observed. As a consequence, the compound shows efficient dual emission, consisting of blue fluorescence and green phosphorescence with an overall emission quantum yield of similar to 100% over the investigated temperature range. Our investigation sheds light on this extraordinary dual emission behavior, which is unique for a heavy-atom transition metal compound. Direct ISC processes in Pt(pop-BF2) are largely forbidden due to spin-, symmetry-, and Franck-Condon overlap-restrictions and, therefore, the ISC time is as long as 29 ns for T < 100 K. With temperature increase, two different thermally activated pathways, albeit still relatively slow, are promoted by spin-vibronic and vibronic mechanisms, respectively. Thus, distinct temperature dependence of the ISC processes results and, as a consequence, also of the fluorescence/phosphorescence intensity ratio. The phosphorescence lifetime also is temperature-dependent, reflecting the relative population of the triplet T-1 substates E-u and A(1u). The highly resolved phosphorescence shows a similar to 220 cm(-1) red shift below 10 K, attributable to zero-field splitting of 40 cm(-1) plus a promoting vibration of 180 cm(-1).
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TRIPLET EXCITED-STATES; CHARGE-TRANSFER STATES; FEMTOSECOND FLUORESCENCE; DIPLATINUM(II,II) COMPLEXES; PHOTOPHYSICAL PROPERTIES; ELECTRONIC SPECTROSCOPY; POLYPYRIDINE COMPLEXES; DIPHOSPHITE COMPLEXES; RELAXATION DYNAMICS; STRUCTURAL-CHANGE; |
| 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: | 03 Apr 2019 11:37 |
| Last Modified: | 03 Apr 2019 11:37 |
| URI: | https://pred.uni-regensburg.de/id/eprint/3260 |
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