Sequential protonation of meso-[p-(dimethylamino)phenyl]porphyrins: charge-transfer excited states producing hyperporphyrins

Ojadi, Emmanuel; Linschitz, Henry; Gouterman, Martin; Walter, Robert I.; Lindsey, Jonathan S.; Wagner, Richard W.; Droupadi, P. R.; Wang, Wending

doi:10.1021/j100152a025

Cited by 106 publications

(137 citation statements)

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“…[26] Introduction of basic groups such as pyridyl and aminophenyl at the meso-positions of porphyrin moiety leads to a decrease in the basicity of the nitrogen atoms of the pyridyl substituents due to the electron-donation from the meso-substituents to the porphyrin core. [27,28] Consequently, protonation of the pyridyl groups of meso-tetra(pyridyl) porphyrins and formation of hexaprotonated species occur in very acidic solutions i.e. at pH ≈ 0.…”

Section: Resultsmentioning

confidence: 99%

Facile Purification of meso-Tetra(pyridyl)porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins

Zakavi¹,

Mojarrad²,

Yazdely³

2012

MHC

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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.

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Section: Resultsmentioning

confidence: 99%

Facile Purification of meso-Tetra(pyridyl)porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins

Zakavi¹,

Mojarrad²,

Yazdely³

2012

MHC

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“…This indicates that it is the number of substituents, but not the symmetry of their arrangement, that control the electronic states of the molecule. 36 All absorption bands are relatively broad (e.g. the separation between Q-bands is not as sharp as that of tetraphenyl porophyrin, TPP).…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic, Redox and Biological Studies of Push-Pull Porphyrins and Their Metal Complexes

Rajesh¹,

Rahiman²,

Bharathi³

et al. 2010

Bulletin of the Korean Chemical Society

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We have synthesized a series of push-pull porphyrins containing both donor and acceptor substituents at the mesopositions and have examined their spectral and biological properties. The push-pull porphyrins containing both strong donor NH2 and acceptor NO2 at meso-positions, in which donor group condensed with the ligand, (2,6-bis(4-methylpiperazine-1-yl-methyl)-4-formlyphenol (L) to form imine linkages with porphyrin. The Schiff base ligand 5-[4-(2,6-bis(4-methylpiperazine-1-yl-methyl)-4-iminomethylphenol)phenyl]-10,15,20-tris(4-nitrophenyl) porphyrin [an3(TPP)L] can be synthesized from 2,6-bis(4-methylpiperazine-1-yl-methyl)-4-formylphenol (L) and 5-(4-aminophenyl)-10, 15,20-tris(4-nitrophenyl)porphyrin. The push-pull porphyrin [an3(TPP)L] was metallated to get copper, nickel and zinc complexes. The spectral, electrochemical, antibacterial, antifungal and cytotoxicity properties of all the donor-acceptor push-pull porphyrins and their complexes were characterized and studied.

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“…We have previously shown that such new bands appear in the course of sequential protonation of porphyrins mesosubstituted by 4-dimethylaminophenyl (DMAP) groups [4]. Systematic titration and NMR studies showed that proton addition to these compounds initially occurs at the central pyrrole nitrogens [4,5].…”

Section: Introductionmentioning

confidence: 99%

Calculations on the origin of hyperporphyrin spectra in sequentially protonated meso-(dimethylaminophenyl) porphyrins

Vitasovic

Gouterman

Linschitz

2001

J. Porphyrins Phthalocyanines

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ABSTRACT:The spectra of porphyrins meso-substituted by 4-dimethylaminophenyl groups and protonated at the central pyrrole nitrogens show strong new bands in the visible (450-600 nm) and far-red (700-780 nm). On complete protonation the observed spectra are essentially normal except for enhanced intensity in the farthest red band at $650 nm. The new bands observed with partial protonation have been qualitatively interpreted as hyperporphyrin spectra due to transitions from 'the filled p orbitals on the amino nitrogen atoms … to the porphyrin LUMOs' [Ojadi ECA, Linschitz M, Gouterman M, Walter RI, Lindsey JS, Wagner RW,]. We now report spectra calculated using the CAChe computer program package. The best structures are determined by energy minimization using a semi-empiral AM1 algorithm; a semi-empirical INDO/CI calculation is then used to obtained the excited state transition energies and intensities. The calculated spectra, although generally blue-shifted compared to experiment, reproduce the hyperporphyrin spectra in those cases where they are observed. In these cases, in contrast to species with normal porphyrin spectra, the HOMO or HOMO-1 is not an orbital on the porphyrin ring but is rather a p-orbital on the unprotonated amino nitrogen that extends over the associated phenyl ring. The calculations suggest that the hyperporphyrin transitions are of Ph(p) → Por(p*) origin, where Ph(p) is an orbital on the phenylamine substitutent and Por(p*) is a LUMO on the porphyrin. It is further suggested that in the fully protonated species the intensity enhancement of the farthest red band in an otherwise normal porphyrin spectrum may relate to phenyl character in the HOMO or HOMO-1.

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Sequential protonation of meso-[p-(dimethylamino)phenyl]porphyrins: charge-transfer excited states producing hyperporphyrins

Cited by 106 publications

References 6 publications

Facile Purification of meso-Tetra(pyridyl)porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins

Facile Purification of meso-Tetra(pyridyl)porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins

Spectroscopic, Redox and Biological Studies of Push-Pull Porphyrins and Their Metal Complexes

Calculations on the origin of hyperporphyrin spectra in sequentially protonated meso-(dimethylaminophenyl) porphyrins

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Sequential protonation of meso-[p-(dimethylamino)phenyl]porphyrins: charge-transfer excited states producing hyperporphyrins

Cited by 106 publications

References 6 publications

Facile Purification of meso-Tetra(pyridyl)­porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins

Facile Purification of meso-Tetra(pyridyl)­porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins

Spectroscopic, Redox and Biological Studies of Push-Pull Porphyrins and Their Metal Complexes

Calculations on the origin of hyperporphyrin spectra in sequentially protonated meso-(dimethylaminophenyl) porphyrins

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Facile Purification of meso-Tetra(pyridyl)porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins

Facile Purification of meso-Tetra(pyridyl)porphyrins and Detection of Unreacted Porphyrin upon Metallation of meso-Tetra(aryl) porphyrins