PMR spectra of symmetrical meso-substituted porphyrins and chlorins

Egorova, G. D.; Соловьев, К. Н.; Шульга, А. М.

doi:10.1007/bf00526049

Cited by 6 publications

(12 citation statements)

References 14 publications

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“…11,12 To gain information regarding spectral properties, the chlorins ZnC-B 5 and ZnC were converted to their corresponding oxochlorins using an established procedure. 11 Accordingly, ZnC-B 5 or ZnC was heated in the presence of basic alumina followed by oxidation with DDQ, giving Oxo-ZnC-B 5 or Oxo-ZnC in 47% or 56% yield, respectively (Scheme 1).…”

Section: Reactivity Of Chlorinsmentioning

confidence: 99%

“…In this regard, the availability of zinc chlorins from the chlorin synthesis is particularly attractive given the facile demetalation of the zinc chelates in the presence of weak acid. Thus, treatment of each member of a series of zinc chlorins and a zinc oxochlorin (ZnC, ZnC-T 5 , ZnC-M 10 , ZnC-P 10 , Oxo-ZnC) with TFA in CH 2 Cl 2 afforded the corresponding free base species (H 2 C, H 2 C-T 5 , H 2 C-M 10 , H 2 C-P 10 , Oxo-H 2 C) in good yield (Scheme 2). By contrast, the direct synthesis of other metallochlorins [e.g., Cu(II), Pd(II) ClIn(III)] 1 is attractive only if these are the ultimate metallochlorin targets, given that such tetrapyrrole coordination complexes require severe conditions for demetalation (e.g., concentrated sulfuric acid).…”

Section: Reactivity Of Chlorinsmentioning

confidence: 99%

“…Five chlorins (H 2 C, H 2 C-T 5 , H 2 C-M 10 , H 2 C-T 5 M 10 , and H 2 C-T 5 M 10 P 15 ) and two oxochlorins (Oxo-H 2 C and Oxo-H 2 C-T 5 M 10 ) were exposed to neat TFA-d at 50 °C, and the exchange progress was measured by 1 H NMR spectroscopy (Scheme 4). For example, dissolution of H 2 C in neat TFA-d at 50 °C resulted in a steady decrease over a few hours in the intensity of the resonances from H 15 (9.26 ppm) and H 20 (9.19 ppm) (Figure 1).…”

Section: Reactivity Of Chlorinsmentioning

confidence: 99%

“…Although the rate constants at the 15-and 20-positions for H 2 C-T 5 and H 2 C-T 5 M 10 could not be calculated due to the overlapping resonances of H 15 and H 20 , the reactivity of H 2 C-T 5 and The pseudo first-order rate constants for deuterium exchange at the 15-and 20-positions of chlorins and oxochlorins are summarized in Table 1. The rate constants for H 2 C-T 5 and H 2 C-T 5 M 10 could not be calculated directly; accordingly, the range of minimum and maximum values for the rate constants was estimated from the time of 50% and 75% total conversion (both for the 15-and 20-positions) as described in the following procedure:…”

Section: Reactivity Of Chlorinsmentioning

confidence: 99%

“…The presence of the geminal dimethyl group in the pyrroline ring renders these new synthetic chlorins more synthetically malleable than the existing model synthetic chlorins including mesotetraphenylchlorin, 2 octaethylchlorin, 3 and chlorin. 4,5 In this paper, we describe the examination of sparsely substituted synthetic chlorins in studies of fundamental reactivity. The studies include measuring the kinetics of deuteration for chlorins that bear 0, 1, 2, or 3 meso substituents and no β-substituents, and assessing the regioselectivity of bromination in a series of chlorins that bear 0 or 1 meso substituents.…”

Section: Introductionmentioning

confidence: 99%

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Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. Part 2: Derivatization

et al. 2007

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Section: Reactivity Of Chlorinsmentioning

confidence: 99%

Section: Reactivity Of Chlorinsmentioning

confidence: 99%

Section: Reactivity Of Chlorinsmentioning

confidence: 99%

Section: Reactivity Of Chlorinsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. Part 2: Derivatization

et al. 2007

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Direct Synthesis of Magnesium Porphine via 1-Formyldipyrromethane

2007

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The reaction of 1-formyldipyrromethane (100 mM) in toluene at 115 °C containing DBU (10 mol equiv) and MgBr 2 (3 mol equiv) in the presence of air affords the magnesium chelate Mg(II)porphine in 30-40% yield. The advantages of the new method include simplicity, high concentration, chromatography-free purification, gram-scale synthesis, and avoidance of the poorly soluble free base porphine. Mg(II)porphine exhibits good solubility in common organic solvents and is a valuable core scaffold for derivatization.Porphine (1, Chart 1) is the simplest porphyrin and represents the core macrocycle of naturally occurring and synthetic porphyrins. Due to the presence of eight open β-pyrrole sites and four meso sites, porphine is a potential building block for the elaboration of porphyrin derivatives. In this regard, porphine undergoes selective mono-bromination at a β-position to give 2-bromoporphine. 1 On the other hand, Shi and Wheelhouse showed that the magnesium(II) chelate of porphine (Mg-1) undergoes tetrabromination to give magnesium(II) mesotetrabromoporphine. Subsequent palladium-coupling reactions afforded tetraaryl A 4 -porphyrins, which included target porphyrins that are not easily available by other routes (e.g., with heterocyclic substituents). 2 Senge has shown that porphine reacts with organolithium reagents to provide meso-substituted A-or cis-A 2 -porphyrins, which also are difficult to synthesize by other routes. 3 These reports provide a glimmer of the possible synthetic utility of porphine; however, the practical use of porphine in synthetic chemistry has been thwarted by two vexing and somewhat interrelated limitations: (1) lack of an efficient method of synthesis, and (2) extremely low solubility of the free base porphine (1).Methods for the synthesis of porphine span the past 70 years (see the Supporting Information). 4-16 The reactants employed include pyrrole and formaldehyde, 4,10 pyrrole-2-carboxaldehyde, 5 N,N-dimethylaminomethylpyrrole, 6 and 2-hydroxymethylpyrrole. 7-9,11, 12 The best method to date employs condensation of 2-hydroxymethylpyrrole in an acidified biphasic mixture followed by oxidation with DDQ, which has afforded 30 mg of porphine in 15% yield. 12 An alternative method entails dealkylation of a tetra-tert-butylporphyrin or

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Accessing the near-infrared spectral region with stable, synthetic, wavelength-tunable bacteriochlorins

et al. 2008

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The near-infrared (NIR) spectral region has been comparatively under-utilized for diverse materials and medical applications owing to the lack of chromophores that afford stability, solubility, synthetic malleability, and tunable photophysical features. Bacteriochlorins are attractive candidates in this regard; however, preparation via modification of naturally occurring bacteriochlorophylls or reduction of porphyrins or chlorins has proved cumbersome. To overcome such limitations, a dibromobacteriochlorin (BC-Br 3 Br 13 ) was prepared de novo by the acid-catalyzed condensation of an 8-bromodihydrodipyrrin-acetal. BC-Br 3 Br 13 bears (1) a geminal dimethyl group in each reduced ring to block adventitious dehydrogenation, and (2) bromo groups at the 3-and 13-positions for further chemical modifications. BC-Br 3 Br 13 was subjected to four types of Pd-mediated coupling reaction (Suzuki, Stille, Sonogashira, dehalogenation) to give bacteriochlorins bearing substituents at the 3-and 13-positions (phenyl, vinyl, acetyl, phenylethynyl), and a benchmark bacteriochlorin lacking such substituents. The 3,13divinylbacteriochlorin was transformed to the 3,13-diformylbacteriochlorin. Depending on the substituents at the 3-and 13-positions, the position of the long-wavelength absorption maximum (Q y (0,0) band) lies between 713 and 771 nm, the fluorescence emission maximum lies between 717 and 777 nm, and the fluorescence quantum yield ranges from 0.15 to 0.070. The ability to introduce a wide variety of functional groups via Pd-mediated coupling reactions and the tunable absorption and emission spectral properties suggest that synthetic bacteriochlorins are viable candidates for a wide variety of photochemical applications.

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PMR spectra of symmetrical meso-substituted porphyrins and chlorins

Cited by 6 publications

References 14 publications

Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. Part 2: Derivatization

Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. Part 2: Derivatization

Direct Synthesis of Magnesium Porphine via 1-Formyldipyrromethane

Accessing the near-infrared spectral region with stable, synthetic, wavelength-tunable bacteriochlorins

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