Spectroscopic and Photophysical Properties of ZnTPP in a Room Temperature Ionic Liquid

Concerning correct and incorrect assignments of Soret (S2-S0) fluorescence in porphyrinoids: a short critical review

The relaxation dynamics of electronically excited porphyrinoids are often measured by steady-state and time-resolved fluorescence methods. The unusual occurrence of measurable fluorescence from an upper excited singlet state (often identified as the second electronically excited singlet state, S2) of some porphyrins has, in recent years, prompted a spate of mis-assignments of observed emission from other porphyrinoids excited in the near UV-violet regions of the spectrum. The criteria for correctly assigning fluorescence to a Soret excited state are reviewed. Questionable and mis-assigned reports are identified.

Spectroscopic and photophysical study of the demetallation of a zinc porphyrin and the aggregation of its free base in a tetraalkylphosphonium ionic liquid

Dissolving zinc tetraphenylporphyrin in the tetraalkylphosphonium chloride ionic liquid P4448Cl results in progressive demetallation of the solute and quantitative production of the free base porphyrin.

The solvation dynamics at millisecond scale of Pd(II)-meso-tetra(4-carboxyphenyl)porphine in solid imidazolium-sulfonate-based ionic liquids

The phosphorescence behavior and solvation dynamics of Pd(II)-meso-tetra(4-carboxyphenyl)porphine (Pd-TCPP) in three imidazolium ionic liquids (ILs) has been studied. The phosphorescence excitation and emission position of Pd-TCPP are dependent on the polarity, constituent ions and structure of the ILs. The phosphorescence decay of Pd-TCPP in these ILs is bi-exponential, and the average lifetimes decrease in the following order: 0.844 ms in 1-butylimidazolium p-toluenesulfonate (HBIMTS)>0.472 ms in 1-butylimidazolium trifluoromethane sulfonate (HBIMTfO)>0.412 ms in 1-butyl-3-methylimidazolium p-toluenesulfonate (BMIMTS). The time-resolved phosphorescence emission spectra (TRPES) of Pd-TCPP display apparently blue-shifts with increasing time. The normalized Stokes shift correlation functions C(t) of Pd-TCPP in these ILs are mono-exponential, and the solvation relaxation times are 2.97, 47.7 and 12.1 ms in HBIMTfO, HBIMTS and BMIMTS, respectively. The solvation dynamics may be attributed to the collective motion of the ion pairs composed of imidazolium cations and counter anions to the area surrounding Pd-TCPP.

Photophysical and ligand binding studies of metalloporphyrins bearing hydrophilic distal superstructure

UV-vis absorption and emission studies on zinc and iron porphyrin complexes bearing H-bonding distal superstructures have been performed in two different organic solvents- tetrahydrofuran (THF) (coordinating) and dichloromethane (DCM) (non-coordinating). Quantum yields and lifetimes have been measured for these complexes which are in good agreement with the other reported metalloporphyrins. Binding affinities with anionic ligands such as N3- , CN- , S-2 , F- were monitored for these two complexes in aqueous media and the respective binding constant values were calculated. The Zn complex shows more selectivity towards cyanide while the Fe complex shows more selectivity towards azide.