Self-assembling cobalt(II) porphyrin - fullero [60]pyrrolidine triads. Synthesis and spectral properties in the ground and excited state

• Published in: Journal of organometallic chemistry 2022-10, Vol.977, p.122458, Article 122458
• Main Authors: Ovchenkova, Ekaterina N., Motorina, Elena V., Bichan, Nataliya G., Gostev, Fedor E., Lomova, Tatyana N.
• Format: Article
• Language: English
• Subjects: Axial coordination; Cobalt(II) porphyrin; Fullero pyrrolidine; Liquid-phase self-assembly; Photoinduced electron transfer; Spectroscopy
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2022.122458

•Self-assembly in toluene of donor-acceptor cobalt(II) porphyrin – fullero [60]pyrrolidine triad was established by thermodynamic/kinetic description.•Chemical structure of the triad was studied using spectral methods.•The photoinduced electron transfer in the triad was described by femtosecond pump-probe spectroscopy. Meso‑4-Trifluoromethylphenyl substituted cobalt(II)porphin, CoT(CF3P)P, and its coordination 1: 2 complex (triad) with 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero [60]pyrrolidine, (PyC60)2CoT(CF3P)P, were firstly synthesized and the properties of their molecular solutions were studied. The chemical structure of CoT(CF3P)P and triad was fully confirmed by the UV–vis, IR and 1H NMR spectroscopy and mass spectrometry methods. The triad formation mechanism as the two-step equilibrium characterized by equilibrium constant K1 (5.89 ± 1.50) × 104 M−1 and K2 (7.40 ± 1.66) × 105 M−1 was revealed. Using femtosecond pump-probe spectroscopy measurements, the photoinduced electron transfer in the synthesized triad was described. The excited state lifetime of the precursors, CoTPP, CoT(CF3P)P and the charge separated state lifetime of (PyC60)2CoT(CF3P)P compared with unsubstituted (PyC60)2CoTPP were determined. It was established that the CF3 groups in the porphyrin periphery slightly change the CoTPP/CoT(CF3P)P excited state lifetime and the electron transfer rate constant in the correspondent triads. [Display omitted]