Synthesis of Expanded Crowned Macrocycles Containing Two Pyrrolo[1,2‐a]indole Units

Ojha, Belarani; Laxman, Kandala; Rawat, Nisha; Ravikanth, Mangalampalli

doi:10.1002/ajoc.202200112

Cited by 4 publications

(4 citation statements)

References 27 publications

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“…Synthesis of p– benzi based pentapyrrane (6) : A sample of 1,4‐phenylenebis(thiophene‐5,2‐diyl))bis((4‐(tert‐butyl)phenyl)methanol [41] (1 g, 1.773 mmol) and pyrrole (1.2 ml, 17.730 mmol) were dissolved in 100 mL of CH 2 Cl 2 in a 250 mL of round bottom flask at room temperature and N 2 gas was purged for 10 min. To initiate the reaction, BF 3 ⋅OEt 2 (25 μl, 0.177 mmol) was added and reaction mixture was allowed to stir at room temperature for 30 min.…”

Section: Methodsmentioning

confidence: 99%

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Synthesis and Properties of Nonaromatic Meta‐Benziheptaphyrins and Aromatic Para‐Benziheptaphyrins

Rawat

Ojha

Ravikanth

2022

Chemistry An Asian Journal

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Two examples of nonaromatic m-benziheptaphyrins and two examples of aromatic p-benziheptaphyrins were synthesized by [5 + 2] condensation of appropriate m-benzi pentapyrrane and p-benzi pentapyrrane respectively and bithiophene diol in CH 2 Cl 2 in the presence of one equivalent of TFA under inert conditions for 30 min followed by oxidation with DDQ in open air for 1 h. The 1 H NMR studies carried out at room temperature as well as at lower temperature indicated the nonaromatic nature of m-benziheptaphyrins with inversion of two thiophene rings and aromatic nature of p-benziheptaphyrins with inversion of one of the thiophene ring. The X-ray structure obtained for one of the p-benziheptaphyrins showed a planar conformation with alignment of one of the thiophene ring away from the macrocyclic inner core but maintained its coplanarity with the mean plane and supported the aromatic nature of the macrocycle. The absorption spectra of m-benziheptaphyrins resembled with the nonaromatic systems and showed two intense bands at 445 nm, 555 nm and a very broad band in the region of 600-1100 nm whereas the pbenziheptaphyrin showed three sharp intense bands at 534 nm, 585 nm and 832 nm due to their aromatic nature. The protonation of m-benziheptaphyrins and p-benziheptaphyrins resulted in significant bathochromic shifts in their absorption maxima and showed strong absorption in NIR region. The electrochemical studies indicated that m-& pbenziheptaphyrins undergo oxidations and reductions easily. DFT and TD-DFT studies were in agreement with the experimental observations.

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Section: Methodsmentioning

confidence: 99%

“…The 1,4-phenylenebis(thiophene-5,2-diyl)bis((4-(tertbutyl)phenyl)methanol [41] and 1,3-bis(5-((4-(tert-butyl)phenyl)(1Hpyrrol-2-yl)methyl)thiophen-2-yl)benzene [42] 5 were prepared by following our reported procedures and spectral data (Figure S1-S6) matched with our reported data.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Properties of Nonaromatic Meta‐Benziheptaphyrins and Aromatic Para‐Benziheptaphyrins

Rawat

Ojha

Ravikanth

2022

Chemistry An Asian Journal

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“…The known compounds 4 a and 5 a were prepared by following our reported procedures and spectral data (Figure S4-S6) matched with our reported data. [25] The compounds 1-2 and 4 b, 5 b and 6 a-b were prepared as described below:…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Studies of Di(p‐Benzi)Decaphyrin and Di(9,10‐Anthracenyl)Decaphyrin

Yadav

Rawat

Ravikanth

2022

Chemistry An Asian Journal

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Two novel macrocycles, di(p-benzi)decaphyrin and di(9,10-anthracenyl)decaphyrin have been synthesized by condensing appropriate p-phenylene based pentapyrrane or 9,10-anthracenyl based pentapyrrane with pentafluorobenzaldehyde under acid catalyzed conditions. The pentapyrrane precursors were synthesized over sequence of steps starting with commercially available 1,4-dibromobenzene and 9,10dibromoanthracene. The decaphyrin macrocycles were freely soluble in common organic solvents and characterized and studied by HR-MS, 1D and 2D NMR, absorption, cyclic voltammetry and computational techniques. The 1 H NMR spectra of both decaphyrins were almost similar with very few resonances, indicating their symmetrical nature in solution and the position of chemical shifts of various protons supports nonaromatic nature of decaphyrins. The DFT optimized structures revealed that both decaphyrins showed a doubly twisted figure of eight conformation and the pphenylene rings in di(p-benzi)decaphyrin and anthracenyl rings in di(9,10-anthracenyl)decaphyrin did not participate in π-delocalization with rest of the respective decaphyrin macrocycle. Both decaphyrins showed sharp intense band in the region of 400-500 nm and a broad band in the region of 600-900 nm. The absorption bands of di(p-benzi)decaphyrin were significantly red shifted compared to di(9,10anthracenyl)decaphyrin. The protonated derivatives of decaphyrins generated by addition of TFA to the toluene solution of decaphyrins showed distinct changes in colour and absorption spectral bands. The redox studies indicated that both decaphyrins are electron rich and undergo easier oxidations. The electrochemical and computational studies revealed that HOMO-LUMO energy gap was less in di(pbenzi)decaphyrin compared to di(9,10anthracenyl)decaphyrin supporting the bathochromic shifts of absorption bands in di(p-benzi)decaphyrin. TD-DFT studies were in agreement with the experimental observations.

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“…The crowned porphyrinoids incorporating two pyrroloindole units 44 were also synthesised ( Scheme 11 ) [ 134 ]. The electrochemical studies demonstrated low oxidation potentials, and similarly to previously described systems incorporating a single pyrroloindole unit, compound 44 underwent single-electron oxidation forming stable cation radicals.…”

Section: From Crowned Porphyrins To Crownphyrinsmentioning

confidence: 99%

Tying a knot between crown ethers and porphyrins

Matviyishyn,

Szyszko

2023

Beilstein J. Org. Chem.

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Porphyrins and crown ether hybrids have emerged as a promising class of molecules composed of elements of a tetrapyrrole macrocycle and an oligo(ethylene glycol) segment. These hybrid systems constitute a broad group of compounds, including crowned porphyrins, crownphyrins, and calixpyrrole-crown ether systems forming Pacman complexes with transition metals. Their unique nature accustoms them as excellent ligands and hosts capable of binding guest molecules/ions, but also to undergo unusual transformations, such as metal-induced expansion/contraction. Depending on the design of the particular hybrid, they present unique features involving intriguing redox chemistry, interesting optical properties, and reactivity towards transition metals. In this perspective article, the overview of both the early designs of porphyrin-crown ether hybrids, as well as the most recent advances in the synthesis and characterisation of this remarkable group of macrocyclic systems, are addressed. The discussion covers the strategies employed in synthesising these systems, including cyclisation reactions, self-assembly, and their remarkable reactivity. The potential applications of porphyrin-crown ether hybrids are also highlighted. Moreover, the discussion identifies the challenges associated with synthesising and characterising hybrids, outlining the possible future directions.

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Synthesis of Expanded Crowned Macrocycles Containing Two Pyrrolo[1,2‐a]indole Units

Cited by 4 publications

References 27 publications

Synthesis and Properties of Nonaromatic Meta‐Benziheptaphyrins and Aromatic Para‐Benziheptaphyrins

Synthesis and Properties of Nonaromatic Meta‐Benziheptaphyrins and Aromatic Para‐Benziheptaphyrins

Synthesis and Studies of Di(p‐Benzi)Decaphyrin and Di(9,10‐Anthracenyl)Decaphyrin

Tying a knot between crown ethers and porphyrins

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