Dibenzofuran/Dibenzothiophene-Embedded Dithia-bis(calix)-sapphyrins

Sinha, Abhas Kumar; Sengupta, Rima; Kumar, Ankit; Ravikanth, Mangalampalli

doi:10.1021/acs.joc.9b02912

Cited by 19 publications

(16 citation statements)

References 45 publications

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“…Tellurium-containing dithiasapphyrins 5–8 were synthesized as shown in Scheme . The precursors 16-telluratripyrrane 9 and different substituted bithiophene diols 10–13 were synthesized by following the literature procedures. − One equivalent of 16-telluratripyrrane 9 was condensed with 1 equiv of four different bithiophene diols 10–13 in CH 2 Cl 2 in the presence of 1 equiv of trifluoroacetic acid at room temperature under an inert atmosphere for 1 h followed by oxidation with 2.5 equiv of DDQ in open air at room temperature for an additional 45 min. We followed the formation of required tellura dithiasapphyrins 5–8 by TLC analysis and absorption spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Studies of Core-Modified Tellura Dithiasapphyrins

2022

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Four different aromatic meso-substituted tellurophene-containing dithiasapphyrins were synthesized by acid-catalyzed [3+2] condensation of 16-telluratripyrrane with bithiophene diol in 22–23% yields. The structural, spectral, and electrochemical properties of tellura dithiasapphyrins were studied and compared with those of previously reported aza (pyrrole)- and other heterocycle (furan, thiophene, and selenophene)-containing dithiasapphyrins. Nuclear magnetic resonance studies indicated that the tellurophene ring in tellura dithiasapphyrins is in the normal conformation, facing toward the inner core, but flips in diprotonated derivatives to an inverted conformation, facing away from the macrocyclic core, unlike aza- and other heterocycle-containing dithiasapphyrins in which pyrrole and the corresponding heterocycle ring always prefer to be in inverted conformation in their neutral and protonated forms. The crystal structure obtained for one of the tellura dithiasapphyrins showed that the macrocycle is highly planar and the tellurophene ring is in the normal conformation. The absorption spectra of tellura dithiasapphyrins exhibited slight hypsochromic shifts compared to those of pyrrole- and other heterocycle-containing dithiasapphyrins. The redox studies indicated that the tellura dithiasapphyrins are electron deficient and readily undergoes reductions. Density functional theory and nuclear independent chemical shift studies indicated that the macrocycles are aromatic, and the computational results closely matched the experimental observations.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Studies of Core-Modified Tellura Dithiasapphyrins

2022

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“…In recent times, polycyclic aromatic hydrocarbon/heterocycle (PAH)-embedded porphyrinoids , have emerged as a new class of macrocycles, which have drawn considerable attention in the light of their unique physicochemical and interesting coordination properties. − PAH-embedded porphyrinoids are unique macrocycles resulting from the replacement of one or two pyrrole units of tetrapyrrolic porphyrins with polycyclic aromatic heterocycles/hydrocarbons moieties such as naphthalene − I , phenanthrene − II , biphenyl III , bipyridine IV , dibenzothiophene V , dibenzofuran, benzothiophene, benzofuran, phenanthroline, etc., and some selected examples I – V are presented in Chart . The PAH-embedded macrocycles demonstrate variable degrees of aromaticity and create a unique macrocyclic environment for coordination .…”

Section: Introductionmentioning

confidence: 99%

Bis-(Fluorene)-Embedded Hexaphyrins

Yadav

Ravikanth

2022

J. Org. Chem.

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The polyaromatic hydrocarbon containing expanded porphyrins, bis-(fluorene)-embedded hexaphyrins, were synthesized by condensing fluorene-based tripyrrane with pentafluorobenzaldehyde in CH2Cl2 in the presence of 1 equiv of BF3·OEt2 under an inert atmosphere followed by oxidation with DDQ in open air at room temperature. The reaction worked only when 1 equiv of BF3·OEt2 was added to the reaction mixture under concentrated reaction conditions. The bis-(fluorene)-embedded macrocycles were characterized and studied by high-resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), absorption, electrochemical, and density functional theory (DFT)/time-dependent (TD)-DFT techniques. In 1H NMR, the hexaphyrins showed a few broad unresolved resonances at room temperature, but the NMR spectra were well-resolved at lower temperatures, indicating that the hexaphyrins were very flexible. The DFT-optimized structures indicated that the two fluorene units at the crossing point of the figure-eight loop makes an angle of ∼79.73° with each other, the fluorene moieties maintained their own planarity, and one of the fluorene moieties was not involved in conjugation with the rest of the macrocycle. The absorption spectra of hexaphyrins showed one intense sharp band in the higher energy region and a broad band in the lower energy region. The electrochemical studies indicated that expanded hexaphyrins are relatively electron-rich and showed three easier oxidations and one reduction. The DFT/TD-DFT studies are in agreement with the experimental observations.

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“…Replacement of one or two pyrroles of tetrapyrrolic porphyrins with polyaromatic hydrocarbons/heterocycles (PAHs) resulted in the formation of new types of PAH embedded porphyrins which have received significant attention in recent years because of their unusual and unique characteristics. In recent times, polyaromatic hydrocarbons such as biphenyl [1,2] 1, phenanthrene [3][4][5][6][7] 2 and polyaromatic heterocycles such as phenanthroline, [8] bipyridine [9,10] 3, dibenzothiophene [11] 4, dibenzofuran, [12] benzothiophene [13] /furan, fluorene [14][15][16][17] embedded porphyrins and expanded porphyrins have been synthesized (Scheme 1) and the studies showed that the electronic properties were significantly altered by incorporation of PAH in place of pyrrole ring(s) of porphyrinoids. Furthermore, PAH embedded porphyrinoids have been seen to possess the following unique features (1) stabilizes metals in unusual oxidation states; [18,19] (2) forms organometallic complexes readily by creating unique macrocyclic environment for coordination;…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Stable Nonaromatic Fluorenonephyrin Macrocycle

et al. 2021

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A new derivative of our recently reported nonaromatic fluorenophyrin 5 named fluorenonephyrin 6 was synthesized over a sequence of six steps starting with commercially available fluorene as precursor. Our attempts to direct oxidation of 5 to 6 were not successful. Hence, we synthesized 2,7-bis(phenyl(1H-pyrrol-2-yl)methyl)-9-fluorenone (fluorenone tripyrrane) in five simple steps from fluorene, and condensed it with pentafluorobenzaldehyde under mild acidic conditions in CH 2 Cl 2 followed by oxidation with DDQ and chromatographic purification to afford fluorenonephyrin (9%). 6 was characterized and studied by HR-MS, 1D and 2D NMR spectroscopy, absorption, electrochemical and DFT/TD-DFT techniques. The DFT studies revealed that 6 was more distorted than 5 and that introduction of C=O in the macrocyclic core remarkably distorts the pyrrole rings of the dipyrrin unit from the mean plane of macrocyclic framework. The macrocycle showed a band at around 390 nm and a broad band at around 650 nm. The redox properties indicated that the macrocycle was highly electron-deficient in nature. TD-DFT studies were in accordance with the experimental observations.

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Dibenzofuran/Dibenzothiophene-Embedded Dithia-bis(calix)-sapphyrins

Cited by 19 publications

References 45 publications

Synthesis and Studies of Core-Modified Tellura Dithiasapphyrins

Synthesis and Studies of Core-Modified Tellura Dithiasapphyrins

Bis-(Fluorene)-Embedded Hexaphyrins

Synthesis of Stable Nonaromatic Fluorenonephyrin Macrocycle

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