Controlled scrambling in porphyrin synthesis—selective synthesis of 5,10-disubstituted porphyrins

Cammidge, Andrew N.; Öztürk, Orhan

doi:10.1016/s0040-4039(00)01965-1

Cited by 15 publications

(5 citation statements)

References 14 publications

(3 reference statements)

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“…TLC analysis showed one less polar major spot corresponding to the desired crowned macrocycle 1 – 3 , and a more polar minor spot corresponding to our earlier reported macrocycle IV and one or two more polar unidentified minor spots. The formation of compound IV during the condensation was due to scrambling in presence acid catalyst which is a known phenomenon in porphyrinoid chemistry [23,24] . Column chromatographic purification on basic alumina afforded crowned macrocycles 1 – 3 as violet solids in 10–15% yields.…”

Section: Resultsmentioning

confidence: 99%

Crowned Macrocycles Containing Two Pyrrolo[1,2‐a] Indoles Created By Intramolecular Fusion

Ojha

Laxman

Ravikanth

2021

Chemistry An Asian Journal

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Heterocyclic fused‐ring systems are of utmost importance because of their presence in many natural products with biological activity. Pyrroloindoles are tricyclic heterocycles that are present in various bioactive and medicinally valuable compounds. Herein, we report the synthesis of phenylene‐bridged bis‐pyrrolo[1,2‐a]indole crowned macrocycles 1–3 in which the pyrrolo[1,2‐a]indole moieties were formed via intramolecular fusion. The macrocycles were thoroughly characterized by 1D and 2D NMR, HRMS and X‐ray crystallographic studies. The X‐ray structure revealed that the two pyrrolo[1,2‐a]indole moieties were parallel to each other, and one pyrrolo[1,2‐a]indole unit was deviated by an angle of 9.54° while the other pyrrolo[1,2‐a]indole unit was deviated by an angle of 12.0° from the mean plane defined by 28 core atoms. The macrocycles 1–3 absorb in the visible region and readily undergo oxidations because of their electron rich nature. The macrocycles 1–3 upon treatment with trifluoroacetic acid (TFA) generates the corresponding cation radicals 1–3.+ which were stable in the open air for a week. The cation radicals 1–3.+ absorb strongly in the NIR region and the experimental observations on crowned macrocycles 1–3 were corroborated by DFT and TD‐DFT studies.

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Section: Resultsmentioning

confidence: 99%

Crowned Macrocycles Containing Two Pyrrolo[1,2‐a] Indoles Created By Intramolecular Fusion

Ojha

Laxman

Ravikanth

2021

Chemistry An Asian Journal

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“…Substitution at the 2,6-aryl positions is a common strategy for preventing meso-substituent scrambling in the rational synthesis of asymmetric porphyrins, which would otherwise lead to lower yields and difficulties in chromatographic separation. [65][66][67] Table 4 The energy barrier for meso-aryl flipping with different substituents at the b 1 , b 2 and ortho positions corresponding to P1 (kJ mol It is generally accepted that the ortho-substitution of the aryl ring prevents coplanarity of the aryl ring and the pyrrole, which would stabilize the cationic azafulvenium by aromatization. Hence we investigated the rotational energy barrier for the 2,6-dimethyl substituted aryl porphyrin analogues, which was found to be remarkably high, namely 182.7 and 170.6 kJ mol À1 (Table 4 entries 8 + 9).…”

Section: The Effect Of Substituents On Meso-aryl Flippingmentioning

confidence: 99%

How to make a porphyrin flip: dynamics of asymmetric porphyrin oligomers

Shang¹,

Philpott²,

Bampos³

et al. 2015

Phys. Chem. Chem. Phys.

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We present the first predictions of meso-aryl flipping pathways in porphyrin oligomers. In the context of cyclic oligoporphyrins this flipping results in a paddle rotation of each porphyrin monomer in the oligomeric ring. If the monomer porphyrin units are asymmetric, this flipping will have consequences for their supramolecular behaviour. Desymmetrisation of synthetic porphyrins leads to synthetic challenges, and hence these species are not as well studied as the more accessible, symmetric counterparts. We have both simulated and synthesized novel, desymmetrised monomeric and cyclic trimeric porphyrins and we predict that the flipping barrier for a porphyrin monomer within the trimer is 36.7 kJ mol(-1) higher than that for meso-aryl flipping in the monomer. The flipping rates estimated from Variable temperature NMR data are consistent with these results. We have also carried out a systematic investigation of how porphyrinic substituents will affect the dynamics, revealing that adding steric bulk in the right place can facilitate meso-aryl flipping. While supramolecular chemistry often focuses on highly symmetric assemblies, evolution can break molecular symmetry in subtle ways, leading to many pseudosymmetric assemblies in biology, especially protein-porphyrinic complexes that are important for energy harvesting and electron transport systems. The dynamic behaviour we have characterized can be critical for the design and function of these molecules, and hence our results will help inform future efforts in the synthesis of asymmetric porphyrinic assemblies that interact with biomolecules.

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“…The extent of scrambling depends mainly on the nature of the meso ‐substituent in the dipyrromethane. For instance, reports reveal that the presence of strong electron‐withdrawing substituents on the phenyl ring of the dipyrromethane enhances scrambling . In continuous with our previous report on DNA interaction properties of trans ‐pyridyl porphyrins bearing fluoro substituents, we were interested to check the biological properties of trans ‐porphyrins bearing 2/3/4‐pyridyl as well as thienyl substituents.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, reports reveal that the presence of strong electronwithdrawing substituents on the phenyl ring of the dipyrromethane enhances scrambling. [16][17][18][19] In continuous with our previous report [20] on DNA interaction properties of transpyridyl porphyrins bearing fluoro substituents, we were interested to check the biological properties of trans-porphyrins bearing 2/3/4-pyridyl as well as thienyl substituents. In this line, during the synthesis of trans-porphyrin with 3-pyridyl substituents, we have isolated the scrambled product namely, 5-(3'pyridyl)-10,15,20-tri(2/3-thienyl)porphyrins (S1a and S2a) with reasonable yield (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

A₃B Porphyrins Bearing Thienyl/Pyridyl Moieties Obtained via Scrambling: Characterization, DNA interaction and Anticancer Studies

2018

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Condensation of 3‐pyridine carboxaldehyde with 2/3‐thienyl dipyrromethanes in presence of acid catalyst gives 5‐(3′‐pyridyl)‐10,15,20‐tri(2/3‐thienyl)porphyrins (S1a and S2a) due to scrambling along with the expected trans‐porphyrins. The corresponding copper(II) and zinc(II) porphyrins were also synthesized. Moreover, to study their biological properties their cationic derivatives were obtained. All the complexes were characterized by UV‐Vis, fluorescence, NMR spectroscopy, mass spectrometry and cyclic voltammetry. The cationic porphyrins bind with DNA non‐intercalatively; show singlet oxygen mediated photocleavage; phototoxic to A549 lung cancer cells through apoptotic pathway.

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Controlled scrambling in porphyrin synthesis—selective synthesis of 5,10-disubstituted porphyrins

Cited by 15 publications

References 14 publications

Crowned Macrocycles Containing Two Pyrrolo[1,2‐a] Indoles Created By Intramolecular Fusion

Crowned Macrocycles Containing Two Pyrrolo[1,2‐a] Indoles Created By Intramolecular Fusion

How to make a porphyrin flip: dynamics of asymmetric porphyrin oligomers

A₃B Porphyrins Bearing Thienyl/Pyridyl Moieties Obtained via Scrambling: Characterization, DNA interaction and Anticancer Studies

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Controlled scrambling in porphyrin synthesis—selective synthesis of 5,10-disubstituted porphyrins

Cited by 15 publications

References 14 publications

Crowned Macrocycles Containing Two Pyrrolo[1,2‐a] Indoles Created By Intramolecular Fusion

Crowned Macrocycles Containing Two Pyrrolo[1,2‐a] Indoles Created By Intramolecular Fusion

How to make a porphyrin flip: dynamics of asymmetric porphyrin oligomers

A3B Porphyrins Bearing Thienyl/Pyridyl Moieties Obtained via Scrambling: Characterization, DNA interaction and Anticancer Studies

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A₃B Porphyrins Bearing Thienyl/Pyridyl Moieties Obtained via Scrambling: Characterization, DNA interaction and Anticancer Studies