Syntheses and Photophysical Behavior of Porphyrin Isomer Sn(IV) Complexes (original) (raw)
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Chemistry-a European Journal, 2007
Mixed cyclization of 3-mono-, 4-mono-, or 4,5-di(porphyrinated) phthalonitrile compounds 2, 3, or 6 and unsubstituted phthalonitrile with the half-sandwich complex [EuIII(acac)(Pc)] (Pc=phthalocyaninate, acac=acetylacetonate) as the template in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-pentanol afforded novel porphyrin-appended europium(III) bis(phthalocyaninato) complexes 7–9 in 30–40 % yield. These mixed tetrapyrrole triads and tetrad were spectroscopically and electrochemically characterized and their photophysical properties were also investigated with steady-state and transient spectroscopic methods. It has been found that the fluorescence of the porphyrin moiety is quenched effectively by the double-decker unit through an intramolecular photoinduced electron-transfer process, which takes place in several hundred femtoseconds, while the recombination of the charge-separated state occurs in several picoseconds. By using different phthalocyanines containing different numbers of porphyrin substituents at the peripheral or nonperipheral position(s) of the ligand, while the other unsubstituted phthalocyanine remains unchanged in these double-deckers, the effects of the number and the position of the porphyrin substituents on these photophysical processes were also examined.
2007
To have a better understanding of and, as the final target, to mimic the natural photosynthetic process, much effort has been devoted to the study of various photosynthesis model compounds, including their synthesis, structure, and in particular photophysical properties involving electronand/or energy-transfer processes. Apart from the biological relevance, these compounds have also attracted further research interest due to their many potential applications in solar energy transfer and molecular-scale optoelectronics and photonics. It is now well known that the key step in photosynthesis is the chain electron transfer across the membrane that happens in the reaction center (RC). The RC contains a bacteriochlorophyll dimer with a slipped cofacial orientation, called a “special pair”, as the primary donor for the electron transfer, which leads to a steady charge-separated state. Owing to a molecular structure which is closely related to that of bacteriochlorophyll in the RC, porphyri...
Inorganic Chemistry, 1998
Synthesis of a new symmetrical 1,4,8,11,15,18,22,25-octahexyloxy-2,3,9,10,16,17,23,24-octa-(3,5-dichlorophenyl)phthalocyaninato zinc(II), ZnPc, has been described and characterized by 1 H NMR, 13 C NMR, MS, UVeVis, and IR spectrometry. The newly prepared ZnPc is soluble in organic solvents and is not aggregated in solution. The photophysical properties were studied by steady-state absorption and emission, cyclic voltammetry, and nanosecond transient absorption techniques. The prepared ZnPc absorbs and emits at longer wavelengths compared to that of reported phthalocyanine derivatives. The electron-donating properties of the ZnPc have been examined by mixing it with the electron-accepting dicyanoperylene-3,4,9,10-bis(dicarboximide), PDICN 2 . The recorded nanosecond transient spectra in the visible/near-IR region showed clearly the electron-transfer from the triplet-excited state of the ZnPc to PDICN 2 with a rate of 3.40 Â 10 8 M À1 s À1 . Light absorption in a wide section of the solar spectrum, favorable redox properties, and the electron-transfer properties suggest usefulness of the ZnPc in lightenergy harvesting and developing optoelectronic devices.
Journal of Fluorescence, 2020
New porphyrin analogues have been designed and synthesized using pyrrole, various aldehydes and propionic acid. The formation of desired compounds was analyzed by utilizing the spectral analysis such as IR, NMR and Mass spectroscopy. The studies on absorption and fluorescence emission of synthesized porphyrins were used to evaluate photophysical characteristics such as molar excitation coefficient and Stokes shift. The estimated values of fluorescence lifetime and fluorescence quantum yield of synthesized porphyrins were found to be variable due to the presence of change in the electron donating and withdrawing characters. The efficiency of generation of singlet oxygen by each synthesized porphyrin as photosensitizer was measured in terms of singlet oxygen quantum yield through photooxidation of 9,10-dimethylantharacene. The obtained singlet oxygen quantum yield values were found to be higher in case of porphyrins those have more electron withdrawing characters rather than donating characters as compared to reference 5,10,15,20-tetraphenylporphyrin (H 2 TPP). The singlet oxygen quantum yield values of synthesized porphyrins varied from 0.52 to 0.66. Pleasingly, some of synthesized porphyrins are found to be photostable and competent to discover as PDT agents as compared to reference H 2 TPP.
Polyhedron, 2013
The synthesis and characterization of meso-carboxyphenylporphyrins metallated with transition metals Pt, Pd, Rh, and Ru are described. The photophysical properties of the dyes were investigated by UV-Vis absorption, emission spectroscopy and cyclic voltammetry. Structures of platinum and palladium derivatives were elucidated by X-ray. The activity of the formed complexes as dyes for DSSCs was studied, however the performance is rather low compared to the reference dye N719.
Solar Energy Materials and Solar Cells, 2010
Three porphyrin dyes were investigated: basic tetraphenylporphyrin (TPP), fluorine tetraphenylporphyrin symmetrically substituted with twelve fluorine atoms (TPPF 12) and chlorine tetraphenylporphyrin symmetrically substituted with twelve chlorine atoms (TPP Cl 12). TPP without external atoms was used as a standard sample. Photoelectrochemical examinations (short-circuit photocurrent in the second time scale) combined with the spectroscopic methods (absorption, fluorescence, photoacoustics supported by the laser-induced optoacoustic spectroscopy) were applied. On the basis of absorption and fluorescence spectra some spectral parameters were estimated, whereas with photoacoustic methods the thermal parameters and kinetics of thermal relaxation in the microsecond time scale were evaluated. The studies of the dyes in the range from about 10 À 6 M up to 10 À 3 M show the absence of aggregated structures although dye fluorescence behavior could indicate the presence of weakly interacting dye molecules when the dyes are in their excited states. The results show that the changes in fluorescence behavior indicate redistribution of the electron density in the molecular macroring upon linkage of the fluorine and chlorine atoms to the main molecular core. The results of the photocurrent and spectral examinations were interpreted in terms of occurrence of mesomeric and inductive effects; photocurrent enhancement in the chlorinated porphyrin (TPPCl 12) versus the free-based (TPP) and fluorinated (TPPF 12) porphyrins support the occurrence of the mesomeric effect which dominates over the inductive one in TPPCl 12 , whereas in TPPF 12 the inductive effect is essential and can lead to photocurrent declining.
Synthesis and Emission Properties of meso-Substituted Porphyrins
Jurnal Teknologi, 2014
ABSTRACT Discovering of various organic dyes including porphyrins have attracted considerable attention to mimic the energy and electron transfer process for the artificial photosynthetic model systems which can be applied in developing optoelectronic devices. The accessibility on tailoring porphyrin properties makes them a good candidate to, be developed as the red light emitting materials for these applications. Thus, symmetrical and unsymmetrical molecular models of porphyrins with appended fluorenyl components and extended π electrons conjugated system were synthesized towards increasing the efficiency of energy and electron transfer. In the photophysical studies, the emission spectra proposed the evidence of energy transfer of appended fluorenyl arms into the porphyrin macrocyclic whereas the extension of conjugating system in porphyrins exhibits lower absorption energy and intensified the red fluorescent properties.
New A3B porphyrins as potential candidates for theranostic. Synthesis and photochemical behaviour
Dyes and Pigments, 2019
The study reports a series of results obtained by synthesis, spectral and morphological analysis of new tetrapyrrolic structures: 5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (P1.2), Zn(II)-5-(4-hydroxy-3methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Zn(II)1.2) and Cu(II)-5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Cu(II)1.2), as potential candidates for theranostics. Porphyrins were obtained by microwave synthesis under solvent-free conditions and characterized by elemental analysis, FT-IR, UV-Vis and NMR spectroscopies. The absorption properties of the synthetized compounds were studied in different solvents (ethanol, polyethylene glycol 200, dimethylsulfoxide, dichloromethane, chloroform). The spectral profile of the new porphyrins was completed by studying the fluorescence emission and singlet oxygen formation quantum yields. P1.2 and Zn(II)1.2 exhibit fluorescence while for Cu(II)1.2 the fluorescence emission is negligible. P1.2 and Zn(II)1.2 exhibited photodynamic therapy (PDT) acceptable values of singlet oxygen generation. In the case of Cu(II)1.2 this parameter is reduced ca. 5 times. For powdered samples of P1.2 adsorbed onto powdered PEG a detailed study was performed correlating the fluorescence emission intensity with sample absorption to determine the concentration range where aggregation does not occur. Fluorescence emission quantum yields and lifetimes were determined for all samples under study to determine the useful range of concentrations for PDT use. Atomic force microscope (AFM) studies were also made, which exhibit the aggregate species formation for high loadings of the porphyrin P1.2 adsorbed onto specific surfaces.
Chemistry - A European Journal, 2012
Supporting information for this article, including general experimental methods, redox properties, reactivity, NMR spectra for new compounds, absorption spectra, MCD spectra, and theoretical calculations, is available on the WWW under http://dx.doi.org/10.1002/ chem.201201664. Figure 1. Tetrathiaporphyrin dication S 4 P 2+ (1).