•Two novel dyads in which PTZ connected at β-pyrrolic position of either free base porphyrin/corrole with vinylic spacer.•Photoinduced singlet-singlet energy transfer from PTZ to corrole/porphyrin was observed (λex = 310 nm).•The energy transfer is more efficient in TPP-PTZ (99%) than the TPC-PTZ (96–98%) when excitation of the dyad at 310 nm.•Quenched emission of porphyrin in TPP-PTZ dyad was observed due to photoinduced electron transfer (λex = 420 nm).•Solvent dependent rates of the energy and electron transfer was discussed.Two novel donor-acceptor dyads, in which phenothiazine (PTZ) connected at β-pyrrolic position of either freebase corrole (TPC) or freebase porphyrin (TPP) via vinylic spacer have been synthesized. Both the dyads were characterized by ESI-MS, IR, 1H NMR (1D and 2D 1H-1H COSY and J-Resolved), UV–Vis, Study state Fluorescence, Time-resolved fluorescence (Time-correlated single photon counting (TCSPC), Streak Camera) as well as electrochemical methods. In the absorption spectra of the dyads, both Soret and Q-bands were red shifted by 8–20 nm indicating weak electronic communication between the two chromophores. However, the fluorescence emission from the PTZ of the dyad was efficiently quenched (96–99%) as compared to pristine PTZ where the dyad was excited at 310 nm, which is attributed to singlet-singlet excited energy transfer. Fluorescence emission from porphyrin part of the TPP-PTZ dyad also quenched when excite the dyad at 420 nm, which is ascribed to photoinduced electron transfer from ground state of PTZ to excited state of porphyrin. In contrast, when excite the corrole at 420 nm in TPC-PTZ dyad, we found there are no significant changes in photophysical properties. In both the cases the solvent dependence of the rate of energy and electron transfer was observed.Download high-res image (279KB)Download full-size image

Photoinduced electron transfer (ET) in Mo2 dimers, [Mo2(DAniF)3]2(μ-E2C(ph)CE2) (DAniF = N,N′-di(p-anisyl)formamidinate, E = O or S), has been studied by femtosecond transient spectral techniques. Using a 355 nm laser pulse, the δ electrons on the Mo–Mo quadruple bonds are selectively excited and subsequent charge separation yields diradicals [Mo2]˙−–ph–[Mo2]˙+ and [Mo2]–ph˙−–[Mo2]˙+. The charge separation (CS) and recombination (CR) rates are derived by fitting the decay kinetic data of the excited states. Surprisingly, it is found that the CR rate constants (kCR-1, ∼1012 s−1) for [Mo2]˙−–ph–[Mo2]˙+ are larger than the data (kCR-2) for [Mo2]–ph˙−–[Mo2]˙+ by about one order of magnitude, although in the first case, the ET distance is doubled and the electronic coupling between the donor and acceptor is weaker. Optical analyses reveal that the free energy changes (ΔG°) for the two CR processes correspond to the δ → δ* and the metal (δ) to bridging ligand (π*) transition energies, respectively, and thus, the ET kinetics is dominated likely by the driving force (−ΔG°).

•A new phosphorus(V) corrole 1-P was synthesized and characterized.•The interaction of 1-P and calf thymus DNA (CT-DNA) was studied by multi-spectroscopic methods and the photonuclease activity of 1-P was examined by agarose gel electrophoresis.•Phosphorus(V) corrole exhibits significant photocytotoxic activity to tumor cells.A new phosphorus(V) corrole, 10-(4-hydroxylphenyl)-5,15-bis(pentafluorophenyl)corrolato (trans-dihydroxo)phosphorus(V) 1-P, was synthesized and characterized. The interaction of 1-P with calf thymus DNA (CT-DNA) was studied by multi-spectroscopic methods. The photonuclease activity of this complex was examined by agarose gel electrophoresis. 1-P may bind to CT-DNA via an outside binding mode and display good photonuclease activity. 1-P displayed low dark toxicity but high photocytotoxic activity against H460 and A549 tumor cell lines.

The interaction between a water-soluble anionic Ga(III) corrole [Ga(tpfc)(SO3Na)2] and calf thymus DNA (ct-DNA) has been investigated by using femtosecond transient absorption spectroscopy. A significant broadening from 570 to 585 nm of positive absorption band of the blend of Ga(tpfc)(SO3Na)2 and ct-DNA (Ga(tpfc)(SO3Na)2-ctDNA) has been observed from 0.15 to 0.50 ps after photoexcitation of Ga(tpfc)(SO3Na)2 into the Soret band. The control experiment has been performed on the model DNA ([poly(dG-dC)]2) rich in guanine bases, which exhibits a similar spectral broadening, whereas it is absent for [poly(dA-dT)]2 without guanine bases. The molecular orbital calculation shows that HOMO of Ga(tpfc)(SO3Na)2 is lower than that of guanine bases. The results of the electrochemical experiment show the reversible electron transfer (ET) between Ga(tpfc)(SO3Na)2 and guanine bases of ct-DNA is thermodynamically favorable. The dynamical analysis of the transient absorption spectra reveals that an ultrafast forward ET from the guanine bases to Ga(tpfc)(SO3Na)2 occurs within the pulse duration (156 fs), leading to the formation of an intermediate state. The following back ET to the ground state of Ga(tpfc)(SO3Na)2 may be accomplished in 520 fs.

The luminescence, excited-state absorption, and singlet oxygen generation measurements were performed on three kinds of halogenated corroles: monohydroxyl halogenated corroles (Corrole-F, Corrole-Cl, Corrole-I), peripherally fluorine-substituted corroles (F0, F5, F10, F15), and gallium complexes (F10-Ga, F15-Ga). The fluorescence intensities progressively decrease whereas the triplet quantum yields, oxygen quenching rates, and singlet oxygen quantum yields increase with the increasing of the monohydroxyl halogen atomic weight. Replacing hydrogen atoms of meso-phenyl groups with fluorine atoms induces the blue-shifts of the emission spectra, higher triplet quantum yield, and smaller oxygen quenching rates. Of all peripherally fluorine-substituted corroles, F10 exhibited the highest singlet oxygen quantum yield. In comparison with the free base corroles, both gallium corrole complexes display much stronger fluorescence with the large blue-shifts of emission peaks and slightly higher triplet quantum yields but smaller oxygen quenching rates and singlet oxygen quantum yields. The reasons for the different photophysical behaviors of these corroles are discussed.

Photoinduced electron transfer (ET) in Mo2 dimers, [Mo2(DAniF)3]2(μ-E2C(ph)CE2) (DAniF = N,N′-di(p-anisyl)formamidinate, E = O or S), has been studied by femtosecond transient spectral techniques. Using a 355 nm laser pulse, the δ electrons on the Mo–Mo quadruple bonds are selectively excited and subsequent charge separation yields diradicals [Mo2]˙−–ph–[Mo2]˙+ and [Mo2]–ph˙−–[Mo2]˙+. The charge separation (CS) and recombination (CR) rates are derived by fitting the decay kinetic data of the excited states. Surprisingly, it is found that the CR rate constants (kCR-1, ∼1012 s−1) for [Mo2]˙−–ph–[Mo2]˙+ are larger than the data (kCR-2) for [Mo2]–ph˙−–[Mo2]˙+ by about one order of magnitude, although in the first case, the ET distance is doubled and the electronic coupling between the donor and acceptor is weaker. Optical analyses reveal that the free energy changes (ΔG°) for the two CR processes correspond to the δ → δ* and the metal (δ) to bridging ligand (π*) transition energies, respectively, and thus, the ET kinetics is dominated likely by the driving force (−ΔG°).