<p>This thesis concerns electron transfer reactions from different excited states in porphyrins, and the effect of changing the energy of the link connecting the donor and acceptor. Photoinduced electron transfer, and subsequent processes were studied using ultrashort laser pulses and nanosecond laser flash photolysis.</p><p>Excitation of Zn(II)-porphyrins in the Soret band lead to population of the higher lying S<sub>2</sub> state. The lifetime and transient absorption spectrum was measured for the S<sub>2</sub> state. When an electron acceptor was attached to the Zn(II)-porphyrin, either as an ion pair, or covalently bound through an amide link, electron transfer was found to compete with S<sub>2</sub> to S<sub>1</sub> relaxation. In the ion pair, electron transfer was faster than 200 fs, with a lifetime of the charge separated state of 1.3 ps. Further, in the covalently linked dyad, the Zn(II) porphyrin triplet state was repopulated from a charge transfer state.</p><p>In [2]-rotaxanes, the Zn(II) porphyrin donor (ZnP) and Au(III) porphyrin acceptor (AuP<sup>+</sup>) are not connected by a direct covalent link. Selective excitation of either the ZnP or the AuP<sup>+</sup> resulted in rapid electron transfer from the ZnP to the AuP<sup>+</sup>. The bis-phenanthroline link connecting the. different porphyrins was changed by coordination of Cu(I) or Ag(I). Electron transfer from the <sup>1</sup>ZnP singlet was unaffected by coordination of either Ag(I) or Cu(I), while electron transfer to the <sup>3</sup>AuP<sup>+</sup> triplet was in the Ag(I) link found to occur by an enhanced superexchange, and by a sequential mechanism in the Cu(I) coordinated link.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-1080 |
| Date | January 2000 |
| Creators | Andersson, Mikael |
| Publisher | Uppsala University, Department of Physical Chemistry, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 578 |
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