| Autor: |
Shilov RA; Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 Saint Petersburg, Russia., Podkorytov IS; Biomolecular NMR Laboratory, St. Petersburg State University, 7-9 Universitetskaya Emb., 199034 Saint Petersburg, Russia., Kisel KS; Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 Saint Petersburg, Russia., Galenko EE; Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 Saint Petersburg, Russia., Karpitskaya DO; Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 Saint Petersburg, Russia., Rodionov IA; Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 Saint Petersburg, Russia., Shakirova JR; Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 Saint Petersburg, Russia., Tunik SP; Institute of Chemistry, St. Petersburg State University, Universitetskii av., 26, 198504 Saint Petersburg, Russia. |
| Abstrakt: |
A series of luminescent binuclear ([dppm{Pt(NNC)} 2 ] 2+ ) and mononuclear ([PPh 3 Pt(NNC)] + ) complexes containing pincer ligands were synthesized and characterized. Photophysical characteristics of both types of complexes were studied in dichloromethane solution. In the solid phase, the binuclear compounds adopt a syn configuration where the {Pt(NNC)} fragments are held together due to intramolecular Pt-Pt bonding and π-stacking of the pincer ligand aromatic systems. Analysis of the complexes' molecular structure in solution by multinuclear NMR spectroscopy showed that the stacked intramolecular configuration is retained in fluid media, which is in complete agreement with a considerable red shift of the emission wavelength due to formation of the intramolecular Pt-Pt bond, leading to the transformation of an emissive excited state to 3 MMLCT. It was also found that triethylamine quenches the emission of both types of complexes; the mechanism of quenching is a combination of dynamic and static channels of excited-state deactivation. In the case of binuclear complexes, deprotonation of the dppm methylene bridge by triethylamine also contributes to the chromophore quenching. To explain the observed chemistry of binuclear complex interactions with Et 3 N, a chemical equilibrium scheme was suggested, which was confirmed by quantitative monitoring of the 31 P signal variations as a function of triethylamine concentration. |
