Porphyrins in analytical chemistry. A review (original) (raw)
Related papers
Potential of porphyrins as chromogenic reagents for determining metals in capillary electrophoresis
Journal of Chromatography A, 2009
Although capillary electrophoresis (CE) with photometric detection is a well-established technique for the determination of various inorganic ions, its limited sensitivity has hindered greater development in this area. In this work, we used a mixture of metals consisting of Co(II), Ni(II), Zn(II) and Mn(II) to demonstrate that the sensitivity of CE with ultraviolet-visible (UV-vis) detection can be improved by using chromogenic reagents such as porphyrins. To this end, the metals were reacted with 5,10,15,20-tetrakis(4-sulphophenyl)-porphine dodecahydrate (TPPS 4 ) to obtain their respective porphyrinato complexes, which were then separated by CE with a citrate buffer and detected at 410 nm. The ensuing electrophoretic method has a limit of detection (LOD) of 3 × 10 −6 M (180 g L −1 ) for Co(II), 2 × 10 −10 M (0.012 g L −1 ) for Ni(II), 4 × 10 −6 M (260 g L −1 ) for Zn(II) and 4 × 10 −9 M (0.219 g L −1 ) for Mn(II). The method is a highly promising choice for the ultratrace determination of Ni(II) and Mn(II).
Macroheterocycles, 2012
In this study, different basicity of the pyridyl substituents of meso-tetra(pyridyl)porphyrins and the substituents of the common impurities associated with the synthesis of the porphyrins has been utilized to improve and simplify the purification of these porphyrins. Also, diprotonation of meso-tetraarylporphyrins with weak or strong acids and the associated shifts of the Soret and Q(0,0) bands have been used for the spectrophotometric detection of trace to substantial amounts of unreacted porphyrin upon complexation of porphyrins with iron and manganese.
Electrochemical and spectroelectrochemical characterization of meso-tetra-alkyl porphyrins
Electrochimica Acta, 2005
A series of three meso-tetra-alkyl porphyrins (H 2 TAPs) were synthesised and their electrochemical properties were studied in dichloromethane containing either tetra-butyl ammonium perclorate (TBAP) or tetra-butyl ammonium hexafluorophosphate TBA(PF 6) as supporting electrolyte (SE) by cyclic voltammetry and in situ UV/vis spectroelectrochemistry. Values of E 1/2 for the recorded four redox processes of these porphyrins and of the meso-tetra-phenyl porphyrin (H 2 TPP) on glassy carbon and platinum were measured and compared. The redox data collected on the first oxidation and the first reduction processes predict that the value of (LUMO − HOMO) for the H 2 TAPs is lower than for meso-tetra-phenyl porphyrin and, therefore, that the first Q band of the electronic spectra of the H 2 TAPs is red shifted relatively to the same band in the spectrum of H 2 TPP; this shift was indeed found. The second oxidation process of the H 2 TAPs is influenced by the supporting electrolyte used and the dication then formed is consumed by an irreversible chemical reaction. The species produced in this reaction is irreversibly reduced at a considerably lower potential. The electrochemical and spectroelectrochemical data collected are consistent with the occurrence of structural distortion in the macrocycle rings of the H 2 TAPs.
2010
In this study, a series of carboxylic acid functionalised pyrrole derivatives and ferroceneand ruthenocene-containing dipyrromethanes were synthesised. Porphyrin complexes bearing a mono-carboxylic acid functional group in the β-position as well as ferrocene or ruthenocene in the -5-, or -5,10-, or -5,15meso positions have been prepared from these pyrrole derivatives. A series of metal-free tetraphenylporphyrins containing nitro, amino or carboxylic acid functional groups on the para position of one of the phenyl rings were synthesised from pyrrole and a substituted benzaldehyde. In addition, a series of metal-free porphyrins containing an electron-withdrawing CF3 group in the ortho, meta or para positions of a phenyl group in one or two of the four meso porphyrin position as well as three or two electron-donating ferrocenyl or ruthenocenyl group in the other meso porphyrin positions were synthesised though a modified statistical condensation procedure of a substituted dipyrromethan...
Applications of Porphyrins and Metalloporphyrins to Materials Chemistry
ChemInform, 2003
Porphyrins and related macrocycles provide an extremely versatile synthetic base for a variety of materials applications. The exploration of metalloporphyrin assemblies as building blocks for tailored materials properties has found rapid growth during the past decade 1 . In this chapter, we shall review the rather diverse applications of porphyrins to materials chemistry and try to draw the common threads between these topics as possible.
Dualism of Sensitivity and Selectivity of Porphyrin Dimers in Electroanalysis
Analytical Chemistry, 2017
This work uncovers the application of porphyrin dimers for the use in electroanalysis, such as potentiometric determination of ions. It also puts in question a current perception of an occurrence of the super-Nernstian response, as a result of the possible dimerization of single porphyrins within an ion-selective membrane. To study that, four various porphyrin dimers were used as ionophores, namely freebase-freebase, Zn−Zn, Zn-freebase and freebase-Zn. Since the Zn-freebase and freebase-Zn porphyrin dimers carried both anion-and cation-sensitive porphyrin units, their application in ISEs was utilized in both anion-and cation-sensitive sensors. In respect to the lipophilic salt added, both porphyrins dimers were found anion-and cation-sensitive. This allowed using a single molecule as novel type of versatile ionophore (anion-and cationselective), simply by varying the membrane composition. All anion-sensitive sensors were perchlorate-sensitive, while the cation-selective sensors were silver-sensitive. The selectivity of the sensors depended primarily on the porphyrin dimers in the ion-selective membrane.
Chemistry: A European Journal, 2015
Magnesium(II) 10-phenyl-5,15-p-ditolylporphyrin is easily and cleanly transformed by electrolysis.Anitro group is first introduced at the free meso position by anodic substitution. Hydrogenation into the amine is then carried out electrocatalytically under ambient conditions with water as ah ydrogen supplier.T he synthesized porphyrin under the nickel(II) form can be covalently grafted onto ap latinum electrode by electrochemical reduction of the diazonium cation, generated in situ by ar eaction of the nickel(II) aminoporphyrin with sodium nitrite and trifluoroacetic acid. The electrosynthesized thin film gives an electrochemical response typical of ap orphyrin material. Films grown under our conditions have amaximum surface coverage of approximately 510 À10 mol cm À2 .T he modified electrode exhibits ar eproducible electrochemical behavior and ag ood level of stabilityo ver potentialcycling and exposition to air.
ChemElectroChem, 2020
The electrochemistry of β-substituted tetraphenylporphyrins with a single ethyl acetoacetate (EAA), acetylacetone (acac) or ethyl acetate (EA) group and two antipodal H, Br or Ph groups was investigated in CH2Cl2 containing 0.1 M tetrabutylammonium perchlorate (TBAP) before and after addition of base to solution in the form of tetrabutylamonium hydroxide (TBAOH). The trisubstituted porphyrins in their neutral form are represented as MTPP(EAA)X2, MTPP(acac)X2 and MTPP(EA)X2 where TPP is the dianion of tetraphenylporphyrin, M = H2, Ni II , Cu II or Zn II and X = H, Br or Ph. The singly reduced porphyrins are relatively stable on the cyclic voltammetry timescale but this is not the case for the doubly reduced EAA and acac derivatives which are highly reactive at room temperature, leading to a porphyrin product assigned as containing a deprotonated EAAor acac-(enolate) substituent. Enolate-appended porphyrins were also in situ generated by the addition of TBAOH, resulting in mono-anionic porphyrins which are harder to reduce by 110-160 mV as compared to the neutral compounds having the same β-substituents, suggesting a high degree of interaction between the deprotonated EAA-or acac-substituent and the porphyrin π-ring system. The chemically or electrochemically generated enolate-appended porphyrin could also be irreversibly oxidized by one electron at peak potentials between 0.10 and 0.30 V, the exact value depending upon solvent and type of β-diketo substituent.
Ion-Pair Extraction of Metalloporphyrins into Acetonitrile for Determination of Copper(II)
Analytical Chemistry, 1996
Extraction mechanism and solvent structure were studied for the solvent extraction of cationic porphyrin (5,10715,20-tetrakis(1-methyl-pyridinium-4-yl) porphyrin; H~(tmpyp)~") and its metalloporphyrins (MP(n+2)+) into an acetonitrile phase separated from a 1: 1 (vh) mixture of acetonitrile with water by addition of sodium chloride. Wf denotes Cu", Co3+, Fe3+, Li' , Mn3', and Zn2+ and H2P4+ is the free base form of H2tmpyy4+. The separated acetonitrile phase contains a lot of water (more than 4 mol dm-) and sodium chloride (1 x 10' mol dm") that are necessary to extract the highly charged chemical species of the above porphyrin or metalloporphyrins which can not be extracted into normal organic solvents such as chloroform. The extracted chemical species dissociate in the acetonitrile phase and exist in ionized forms. X-ray diffraction analysis indicates the formation of clusters of acetonitrile in the mixed-aqueous organic solvent. An acetonitrile molecule interacts with 2 neighbors at 3.45A in antiparallel and 4.10 A in parallel through dipole-dipole interaction. Water molecules that form hydrogen bonding between water molecules surround the acetonitrile clusters. The porphyrin or metalloporphyrins are preferentially solvated by acetonitrile molecules and are surrounded by acetonitrile clusters.
Current Analytical Chemistry, 2005
This review offers a brief summary of results obtained from separations of the sets of biologically relevant compounds (carboxylic acids, amino acids, peptides, nucleotides and organic phosphates) using open tubular capillary electrochromatography (OT-CEC), in which oligopyrrolic macrocycles serve as the modifiers of the inner fused silica capillary wall surface. Types of interactions leading to improved selectivity of the open tubular capillary electrochromatographic systems and/or to the change of the speed of the electroosmotic flow are also discussed. In addition, selected comparative data on the application of oligopyrrolic macrocycles in other analytical methods, particularly chromatographic and spectrometric techniques, are presented.