A theoretical study of porphyrin isomers and their core-modified analogues:cis-trans isomerism, tautomerism and relative stabilities

Punnagai, M.; Joseph, Seena; Sastry, G. Narahari

doi:10.1007/bf02708278

Cited by 14 publications

(7 citation statements)

References 15 publications

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“…The electronic structure of parent porphycene 1 has been the subject of many studies that used various theoretical models. ,,,,,− Other porphycenes for which calculations have been performed include 1 -Mg; ,, 1 -Zn; 1 -Fe(II); 13 ; , 20 and 21 ; , 25 ; , 38 ; 73 , 74 , and 76 ; 122 ; 125 ; dibenzoporphycenes 169 (without methyl groups) , and 187 ; 169 -(Fe)II; and tetraoxaporphycene 165 …”

Section: Electronic Spectroscopymentioning

confidence: 99%

Spectroscopy and Tautomerization Studies of Porphycenes

2016

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Tautomerization in porphycenes, constitutional isomers of porphyrins, is strongly entangled with spectral and photophysical parameters. The intramolecular double hydrogen transfer occurring in the ground and electronically excited states leads to uncommon spectroscopic characteristics, such as depolarized emission, viscosity-dependent radiationless depopulation, and vibrational-mode-specific tunneling splittings. This review starts with documentation of the electronic spectra of porphycenes: Absorption and magnetic circular dichroism are discussed, together with their analysis based on the perimeter model. Next, photophysical characteristics are presented, setting the stage for the final part, which discusses the developments in research on tautomerism. Porphycenes have been studied in different experimental regimes: molecules in condensed phases, isolated in supersonic jets and helium nanodroplets, and, recently also on the level of single molecules investigated by optical and scanning probe microscopies. Because of the rich and detailed information obtained from these diverse investigations, porphycenes emerge as very good models for studying the complex, multidimensional phenomena involved in the process of intramolecular double hydrogen transfer.

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Section: Electronic Spectroscopymentioning

confidence: 99%

Spectroscopy and Tautomerization Studies of Porphycenes

2016

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“…The unique properties exhibited by the N‐confused porphyrins such as their remarkable ability to act as tetracoordinate ligands to form transition metal complexes, 8 have attracted recent attention. This leads to a flurry of synthetic attempts toward novel porphyrin‐like molecules, with structural variants such as ring or bridge extended, 7 reshuffled, 9 inverted, 10 N‐ and C‐fused, contracted 11, and core‐modified porphyrins 12. The porphyrin isomers reported to date include, corrphycene, hemiporphycene, and isoporphycene obtained by shuffling the four pyrrolic subunits and meso ‐carbon bridge.…”

Section: Introductionmentioning

confidence: 99%

DFT study of core‐modified porphyrin isomers

Soujanya

Punnagai

Bandaru

et al. 2006

Int J of Quantum Chemistry

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B3LYP/6-311ϩG** calculations were performed systematically on 1,2 (syn) and 1,3 (anti) tautomeric forms of oxa-and thia-core-modified porphyrin isomers, which resulted in a total of 86 structures. The structural and energetic variation in all the isomers were analyzed. In corrphycene, hemiporphycene and porphycene the Z forms are more stable compared to the corresponding E forms in both the anti and syn oxa-and thiaporphyrin isomers. In contrast, in the syn isomeric forms of [3.0.1.0], [3.1.0.0] and [4.0.0.0] oxaporphyrins and in both syn and anti forms of thiaporphyrin isomers, Z forms are less stable. The HOMO and LUMO values are both negative and varied in a narrow zone, indicating no dramatic effect on the position of heteroatom substitution on the redox properties. The effect of geometric constraints due to the alteration of meso-bridge length and the hetero atom disposition in the porphyrin core on the relative stabilities of the isomers is analyzed.

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“…The consequence of this is a decrease in the number of Q-bands from four to two or one, accompanied by a shift in λmax of the soret-band (Gouterman, 1961). Most of the Ag-porphyrins had a single Q-band due to the 'sitting-atop' position of silver as a result of its large ionic radius ) relative to the distance between opposite nitrogen atoms (0.4 nm) (Senge, 1999;Punnagia et al, 2004;Smith, 2006). Several researchers have studied the IR spectra of various porphyrins and have assigned certain bands Martell, 1956, 1959;Kincaid and Nakamoto, 1975;Zhang et al, 2003).…”

Section: Molecular Characterizationmentioning

confidence: 99%

Zinc, Tin and Silver Porphyrins (TPP, TCPP, TMPP, THPP, TPPS, TMPyP) as photosensitizers in antibacterial photodynamic therapy for chronic wounds: A screening study

George

Torimiro

Daramola

et al. 2022

Eth J Sci & Technol

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Continuous proliferation of bacteria in a wound delays its healing process, and could further extend to becoming a chronic wound infection. The effectiveness of different porphyrins as a photosensitizer in antibacterial photodynamic therapy for the inactivation of some wound-colonizing bacteria was studied as a screening experiment. Meso-tetra(4-methoxyphenyl) porphyrin, (TMPP), meso-tetra(4-hydroxyphenyl) porphyrin (THPP), meso-tetra(4-carboxyphenyl) porphyrin, (TCPP), meso-tetra(N-methyl-4-pyridyl) porphyrin, (TMPyP) were synthesized, each complexed with zinc, tin and silver. The in-vitro and photo-toxicity properties of the porphyrins and their complexes were assessed on some selected wound colonizing multi-drug resistant bacterial strains (Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis, and Escherichia coli) using agar well diffusion method. Photo-toxicity of the compounds were investigated using a 100-Watt tungsten lamp while the in-vitro toxicity was carried out in the dark. The results were compared with previously reported work carried out by this group on meso-tetra(phenyl)porphyrin (TPP), meso-tetra(4-sulphonatophenyl) porphyrin, (TPPS) and their corresponding Zn, Sn and Ag complexes. Most of the porphyrins showed biocidal activities against three of the test isolates with an exception to Proteus sp. ZnTMPyP and ZnTHPP only showed photo-toxic activities against the four test isolates. While SnTHPP, ZnTPPS, ZnTCPP, and SnTCPP all exhibited both toxic and photo-toxic activities against all four bacterial isolates. The Ag-porphyrins had the poorest inactivation activity.

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A theoretical study of porphyrin isomers and their core-modified analogues:cis-trans isomerism, tautomerism and relative stabilities

Cited by 14 publications

References 15 publications

Spectroscopy and Tautomerization Studies of Porphycenes

Spectroscopy and Tautomerization Studies of Porphycenes

DFT study of core‐modified porphyrin isomers

Zinc, Tin and Silver Porphyrins (TPP, TCPP, TMPP, THPP, TPPS, TMPyP) as photosensitizers in antibacterial photodynamic therapy for chronic wounds: A screening study

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