Study of the photoresponse of a titanium anode coated with solution-processed fullerene-containing metal porphyrin/phthalocyanine films

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.

Fullerene binding effects in Al(III)/Zn(II) Porphyrin/Phthalocyanine photophysical properties and charge transport

We evaluate the fullerene C₆₀ binding effect; through the metal (Al) and through the ligand (Pc,TPP), on the photophysical and charge transport properties of M-porphyrin(TPP)/phthalocyanine(Pc) (M = Al(III), Zn(II)). We perform density functional theory (DFT) and time-dependent DFT calculations for the macrocycle-C₆₀ dyads, showing that all systems studied are thermodynamically favorable. The C₆₀ binding effect on the absorption spectrum is a red-shift of the Q and Soret (B) bands of TPPs and Pcs. The Pc-dyads show longer λ for Q bands (673 nm) than those with TPP (568 nm). AlTPP-C₆₀ and ZnTPP-C₆₀ show a more favorable electron injection to TiO₂ than the analogs Pcs, and the regeneration of the dye is preferred in AlTPP-C₆₀ and AlPc-C₆₀. Zero-bias conductance is computed (10^-4-10^-7 G₀) for the dyads using molecular junctions with Au(111)-based electrodes. When a bias voltage of around 0.6 V up to 1 V is applied, an increase in current is obtained for AlTPP-C₆₀ (10^-7 A), ZnTPP-C₆₀ (10^-7 A), and AlPc-C₆₀ (10^-8 A). Although there is not a unique trend in the behavior of the dyads, Pcs have better photophysical properties than TPPs and the latter are better in the charge transport. We conclude that AlTPP(ZnTPP)-C₆₀ dyads are an excellent alternative for designing new materials for dye-sensitized solar cells or optoelectronic devices.

Novel fluorescence quenching triad based on molybdenum(V) tetra-p-tolylporphyrin and substituted fullero[60]pyrrolidine

With the aim of designing new photoactive donor–acceptor dyads, self-assembly in the (ethoxy)(oxo)(5,10,15,20-(4-methylphenyl)porphinato)molybdenum(V) (O=Mo(OEt)TTP)–2[Formula: see text]-(pyridin-4-yl)-5[Formula: see text]-(pyridin-2-yl)-1[Formula: see text]-(pyridin-2-yl-methyl)pyrrolidino[60]fullerene (Py3F)-toluene systems was quantitatively studied using spectral methods (UV-vis, IR, 1H NMR, mass spectrometry), chemical thermodynamics, and chemical kinetics. Interaction between O=Mo(OEt)TTP and pyridine (Py) proceeding as step equilibriums was preliminarily studied to model the processes above. The novel donor–acceptor triad based on O=Mo(OEt)TTP and Py3F is represented with both quantitative description of its formation and conformation of the chemical structure. Prospects for the study of the triad as a photosynthetic antenna imitator and an active layer in organic solar cells are substantiated by a fluorescence method. Along with this, it has been demonstrated that O=Mo(OEt)TTP is a good candidate for use as an optical and fluorescent chemosensor of volatile organic compounds and nitrogen bases — the building blocks of pharmaceuticals, food components and environmental pollutants.

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.