The Heavy Atom Effect On The Photophysical Properties Of Corrole And Their Gallium Complexes

Corrole chemistry, is considered as important branch of porphyrin chemistry. As corrole has been possessed with unique photochemical and photophysical properties, which get it with great potential application in fluorescent probe, photo dynamic therapy, dye sentized solar cell, etc. Heavy atom effect, which has been considered as one of the most significant factors on influencing the photophysical properties for corroles, actually was investigated relatively scarce. Thus, this paper majorly takes deeper insights into how the heavy atom effect will influence the optical properties especially PDT performance for corroles.1. Three gallium corroles with different fluorine numbers: 5,15-bis(phenyl), 10-pentafluorophenyl corrole gallium complex(1-Ga), 5,15-bis(pent afluoroph enyl),10-phenyl corrole gallium complex(2-Ga), 5,10,15-tris(pentafluorophenyl) corrole gallium complex(3-Ga) and three mono-hydroxyl corroles with different iodine numbers: 10-(2-hydroxyl)phenyl-5,15bis(pentafluorophenyl)corrole 4, 10-(2-hydroxyl-5-iodophenyl)-5,15bis(pentafluorophenyl)corrole 5, 10-(2-hydroxyl-3,5-bisiodophenyl)5,15bis(pentafluor ophenyl) corrole 6 had been synthesized and also characterized by UV-VIS, NMR, MS.2. Halogenated-benzene solvents were used as the source of external heavy atom environment, to study the effect on the photophysical properties of three gallium corroles by using μltraviolet-visible(UV-VIS), steady-state, time-resolved fluorescence, and femtosecond transient absorption spectroscopic techniques; The resμlts showed that the UV-vis peaks for gallium corroles were majorly influenced by the dispersion force in halogenated-benzene solvents; The external effect on the fluorescent properties was anticipated theoretically,i.e, coμld decrease this property effectively thus getting those related parameters decreased like fluorescence quantum yield and fluorescence lifetime; From the analysis of femtosecond transient absorption experiments, Photoinduced electron transfer between the gallium corroles and halogenated benzene solvents was detected by femtosecond transient absorption spectroscopy. The experimental evidence showed that the heavy atom effect of the solvent might lower the charge recombination rate of charge-separated gallium corrole-solvent complexes.3. Structural difference between three mono-hydroxyl corroles had been vividly illustrated via DFT(Density Function Theory) study; UV-VIS demonstrated that the dispersion force in halogenated-benzenes was the dominant force in charging of the electroic absorption peak; Fluoresence emission spectra and fluorescence decay curves mainefested fluorescent property of three mono-hydroxyl corroles in halogenated-benzenes, through calcμlation, we came to find the fluorescence quantum yield for biodinated-corrole 6 in iodobenzene was the minimum value(0.00755), which illustaed the point that double heavt atom effect(inner and external) actually coμld exert over-laid function on impairing the fluorescence for corrles.4. DPA was used to as trapping substance to captive singlet oxygen, in order to qualitatively compare the singlet oxygen generation ability for three mono-hydroxyl corroles in different halogenated-benzenes. In the same halogenated-benzene, the resμlt showed that the mono-iodonated corrole 5 possessed better singlet oxygen generation abilty than other two corroles(4and 6). whereas, for one corrole in different halogenated-benzene solvents, the influencing rμle coμld be expressed as following: Benzene > Fluorobenzene > Iodobenzene > Chlorobenzene > Bromobenzene.5.The singlet oxygen signal luminenscence for three mono-hydroxyl corroles in different halogenated-benzene solvents were measured by steady-state infrared light method, and the intensity of this signal coμld reflect the singlet oxygen generation ability. The resμlts had showed that, in the same halogenated-benzene, the intensity follows the order: 5 > 4> 6, this resμlt was conformed with resμlt obtained from DPA method. But for particμlar corrole in different halogenated-benzene solvents, the influencing law coμld be expressed as following: Benzene > Iodobenzene ≈ Fluorobenzene > Chlorobenzene > Bromobenzene.6. The laser flash photoysis device was set up. And this set-up was used to obtain the transient state absorption spectra for three corroles in different halogenated-benzene solvents, and through decay curves for characteristic peak, we coμld get those triplet lifetime by fitting those curves, hence calcμlating the oxygen quenching rate constant(Kq T) and triplet quantum yield(ΦT), in different solvents, the influencing discipline of Kq T for 5 and 6 just as expressed: Iodobenzene > Chlorobenzene > Fluorobenzene > Bromobenzene. In the aerated condition, 6 exhibited the shortest triplet lifetime and the largest value of oxygen quenching rate constant.in Iodobenzene.