Donor-Acceptor Complexes of (5,10,15,20-Tetra(4-methylphenyl)porphyrinato)cobalt(II) with Fullerenes C60: Self-Assembly, Spectral, Electrochemical and Photophysical Properties

The noncovalent interactions of (5,10,15,20-tetra(4-methylphenyl)porphinato)cobalt(II) (CoTTP) with C₆₀ and 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero[60]pyrrolidine (PyC₆₀) were studied in toluene using absorption and fluorescence titration methods. The self-assembly in the 2:1 complexes (the triads) (C₆₀)₂CoTTP and (PyC₆₀)₂CoTTP was established. The bonding constants for (C₆₀)₂CoTTP and (PyC₆₀)₂CoTTP are defined to be (3.47 ± 0.69) × 10⁹ and (1.47 ± 0.28) × 10¹⁰ M^-2, respectively. ¹H NMR, IR spectroscopy, thermogravimetric analysis and cyclic voltammetry data have provided very good support in favor of efficient complex formation in the ground state between fullerenes and CoTTP. PyC₆₀/C₆₀ fluorescence quenching in the PyC₆₀/C₆₀-CoTTP systems was studied and the fluorescence lifetime with various CoTTP additions was determined. The singlet oxygen quantum yield was determined for PyC₆₀ and the intensity decrease in the ¹O₂ phosphorescence for C₆₀ and PyC₆₀ with the CoTTP addition leading to the low efficiency of intercombination conversion for the formation of the ³C₆₀* triplet excited state was found. Using femtosecond transient absorption measurements in toluene, the photoinduced electron transfer from the CoTTP in the excited singlet state to fullerene moiety was established. Quantum chemical calculations were used for the determination of molecular structure, stability and the HOMO/LUMO energy levels of the triads as well as to predict the localization of frontier orbitals in the triads.

Donor-acceptor interactions of gold(III) porphyrins with cobalt(II) phthalocyanine: chemical structure of products, their spectral characterization and DFT study

In the context of the development of coordination energy-harvesting systems, the axial bonding of cobalt(II) octakis(3,5-di-tert-butylphenoxy)phthalocyanine (1) with gold(III) 2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(pyridin-4-yl)- and (2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(pyridin-3-yl)porphin (2 and 3), the structure, the spectral/electrochemical properties of the resulting donor-acceptor complexes and photoinduced electron transfer in them are studied. The process of the dyad formation passing as self-assembly in the donor-acceptor phthalocyanine-porphyrin systems was explored using UV-Visible, IR, and ¹H NMR spectroscopy and mass spectrometry. The geometric and electronic structures of the dyads were identified using density functional theory (DFT) and time-dependent DFT calculations. The electron transfer in the coordination complexes studied was confirmed by recording the radical ion pairs namely 1˙⁺:2˙^-/1˙⁺:3˙^- and measuring the kinetics of the photoinduction and decay of these states by a femtosecond laser photolysis technique. The effect of the gold(III) porphyrin macrocycle nature in the lifetime of radical ion pairs was shown. The redox potential values for the coordination dyads and the photoelectrochemical parameters defining their perspective in design and understanding of PET systems were observed using the cyclic voltammetry/amperometry methods and the short-circuited electrochemical cell Ti|a dyad film|0.5 M Na₂SO₄|Pt, respectively.

Carbazole-functionalized cobalt(ii) porphyrin axially bonded with C60/C70 derivatives: synthesis and characterization

Depending on the structure of the fullero[60]/[70]pyrrolidine, the carbazole-functionalized cobalt(ii) porphyrin forms donor–acceptor systems of different compositions.

Spectral properties of supramolecular systems based on cobalt(ii)/manganese(iii) phthalocyanine and fullero[60]pyrrolidines with PET

Photoinduced electron transfer in the metallophthalocyanine–fullerene dyads was confirmed and the main “chemical structure – spectral properties” dependences were revealed.