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Amado PSM, Lopes S, Brás EM, Paixão JA, Takano MA, Abe M, Fausto R, Cristiano MLS. Molecular and Crystal Structure, Spectroscopy, and Photochemistry of a Dispiro Compound Bearing the Tetraoxane Pharmacophore. Chemistry 2023; 29:e202301315. [PMID: 37343198 DOI: 10.1002/chem.202301315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 06/23/2023]
Abstract
The molecular structure and photochemistry of dispiro[cyclohexane-1,3'-[1,2,4,5]tetraoxane-6',2''-tricyclo[3.3.1.13,7 ]decan]-4-one (TX), an antiparasitic 1,2,4,5-tetraoxane was investigated using matrix isolation IR and EPR spectroscopies, together with quantum chemical calculations undertaken at the DFT(B3LYP)/6-311++G(3df,3pd) level of theory, with and without Grimme's dispersion correction. Photolysis of the matrix-isolated TX, induced by in situ broadband (λ>235 nm) or narrowband (λ in the range 220-263 nm) irradiation, led to new bands in the infrared spectrum that could be ascribed to two distinct photoproducts, oxepane-2,5-dione, and 4-oxohomoadamantan-5-one. Our studies show that these photoproducts result from initial photoinduced cleavage of an O-O bond, with the formation of an oxygen-centered diradical that regioselectivity rearranges to a more stable (secondary carbon-centered)/(oxygen-centered) diradical, yielding the final products. Formation of the diradical species was confirmed by EPR measurements, upon photolysis of the compound at λ=266 nm, in acetonitrile ice (T=10-80 K). Single-crystal X-ray diffraction (XRD) studies demonstrated that the TX molecule adopts nearly the same conformation in the crystal and matrix-isolation conditions, revealing that the intermolecular interactions in the TX crystal are weak. This result is in keeping with observed similarities between the infrared spectrum of the crystalline material and that of matrix-isolated TX. The detailed structural, vibrational, and photochemical data reported here appear relevant to the practical uses of TX in medicinal chemistry, considering its efficient and broad parasiticidal properties.
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Affiliation(s)
- Patrícia S M Amado
- Center of Marine Sciences, CCMAR, Gambelas Campus, University of Algarve UAlg, 8005-139, Faro, Portugal
- Department of Chemistry and Pharmacy Faculty of Sciences and Technology, Gambelas Campus, University of Algarve UAlg, 8005-139, Faro, Portugal
| | - Susy Lopes
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal
| | - Elisa M Brás
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal
| | - José A Paixão
- CFisUC, Department of Physics, University of Coimbra, 3004-516, Coimbra, Portugal
| | - Ma-Aya Takano
- Department of Chemistry Graduate School of Advanced Science and Engineering, Hiroshima University Higashi-Hiroshima, Hiroshima, 739-8526, Japan
- International Institute for Sustainability with Knotted Chiral Meta Matter (SKCM2) Higashi-Hiroshima, Hiroshima, 739-0046, Japan
| | - Manabu Abe
- Department of Chemistry Graduate School of Advanced Science and Engineering, Hiroshima University Higashi-Hiroshima, Hiroshima, 739-8526, Japan
- International Institute for Sustainability with Knotted Chiral Meta Matter (SKCM2) Higashi-Hiroshima, Hiroshima, 739-0046, Japan
| | - Rui Fausto
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal
- Faculty of Sciences and Letters, Department of Physics, Istanbul Kultur University Ataköy Campus, Bakirköy, 34156, Istanbul, Turkey
| | - Maria L S Cristiano
- Center of Marine Sciences, CCMAR, Gambelas Campus, University of Algarve UAlg, 8005-139, Faro, Portugal
- Department of Chemistry and Pharmacy Faculty of Sciences and Technology, Gambelas Campus, University of Algarve UAlg, 8005-139, Faro, Portugal
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Volkov MA, Novikov AP, Borisova NE, Grigoriev MS, German KE. Intramolecular Re···O Nonvalent Interactions as a Stabilizer of the Polyoxorhenate(VII). Inorg Chem 2023; 62:13485-13494. [PMID: 37599582 DOI: 10.1021/acs.inorgchem.3c01863] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Abstract
The first polyoxorhenate(VII) compound, pyrazolium polyoxorhenate ((C4N2H5)2Re4O15), and two new rhenium(VII) and technetium(VII) salts have been synthesized and studied. The structure of Tc2O7 has been reinvestigated. The [Re4O15]2- polyoxoanion contains four Re(VII) atoms: one with an octahedral environment and three with a tetrahedral environment. Polyoxorhenate is formed in the presence of a buffering agent, pyrazole, the latter maintaining pH = 2.5 during the formation of crystals. The [Re4O15]2- polyoxoanion has novel stoichiometry and the cis-conformation, likely due to the stabilizing intramolecular nonvalence interactions. For the first time, intramolecular interactions of the Re···O, Re···μ-O, and O···O are described (previously known were only intermolecular ones). In all of the compounds, intermolecular Re···O interactions are observed, which, however, in other compounds, do not lead to the formation of polyoxometalates. The Hirshfeld surface analysis showed that the main contribution to intermolecular interactions is made by the O···H/H···O contacts, van der Waals interactions of the H···H for cations, and the O···O for anions. DFT calculations of the [Re4O15]2- geometry, compared with the crystallographic data, revealed a deviation in the angles. Mass spectroscopy of the red polyoxometalate [Tc20O68]4- was carried out for the first time. Comparison of the results of MALDI and LI for the first known polyoxometalates of the manganese subgroup made it possible to find general patterns of oligomerization for rhenium and technetium compounds. The ESI-MS and LI-MS methods applied to solution and crystals Re compounds made it possible to prove rhenium being able to form not only [Re4O15]2- but also heavier polyoxoanions.
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Affiliation(s)
- Mikhail A Volkov
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences, 31 Bldg 4, Leninsky Prosp., Moscow 119071, Russian Federation
| | - Anton P Novikov
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences, 31 Bldg 4, Leninsky Prosp., Moscow 119071, Russian Federation
| | - Nataliya E Borisova
- Department of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow119991, Russian Federation
| | - Mikhail S Grigoriev
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences, 31 Bldg 4, Leninsky Prosp., Moscow 119071, Russian Federation
| | - Konstantin E German
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences, 31 Bldg 4, Leninsky Prosp., Moscow 119071, Russian Federation
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Amado PSM, Costa ICC, Paixão JA, Mendes RF, Cortes S, Cristiano MLS. Synthesis, Structure and Antileishmanial Evaluation of Endoperoxide–Pyrazole Hybrids. Molecules 2022; 27:5401. [PMID: 36080174 PMCID: PMC9457810 DOI: 10.3390/molecules27175401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 11/17/2022] Open
Abstract
Leishmaniases are among the most impacting neglected tropical diseases. In attempts to repurpose antimalarial drugs or candidates, it was found that selected 1,2,4-trioxanes, 1,2,4,5-tetraoxanes, and pyrazole-containing chemotypes demonstrated activity against Leishmania parasites. This study reports the synthesis and structure of trioxolane–pyrazole (OZ1, OZ2) and tetraoxane–pyrazole (T1, T2) hybrids obtained from the reaction of 3(5)-aminopyrazole with endoperoxide-containing building blocks. Interestingly, only the endocyclic amine of 3(5)-aminopyrazole was found to act as nucleophile for amide coupling. However, the fate of the reaction was influenced by prototropic tautomerism of the pyrazole heterocycle, yielding 3- and 5-aminopyrazole containing hybrids which were characterized by different techniques, including X-ray crystallography. The compounds were evaluated for in vitro antileishmanial activity against promastigotes of L. tropica and L. infantum, and for cytotoxicity against THP-1 cells. Selected compounds were also evaluated against intramacrophage amastigote forms of L. infantum. Trioxolane–pyrazole hybrids OZ1 and OZ2 exhibited some activity against Leishmania promastigotes, while tetraoxane–pyrazole hybrids proved inactive, most likely due to solubility issues. Eight salt forms, specifically tosylate, mesylate, and hydrochloride salts, were then prepared to improve the solubility of the corresponding peroxide hybrids and were uniformly tested. Biological evaluations in promastigotes showed that the compound OZ1•HCl was the most active against both strains of Leishmania. Such finding was corroborated by the results obtained in assessments of the L. infantum amastigote susceptibility. It is noteworthy that the salt forms of the endoperoxide–pyrazole hybrids displayed a broader spectrum of action, showing activity in both strains of Leishmania. Our preliminary biological findings encourage further optimization of peroxide–pyrazole hybrids to identify a promising antileishmanial lead.
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Aleksanyan AG, Hakobyan RM, Shahkhatuni AG, Shahkhatuni AA, Attaryan HS. Direct demonstration of tautomeric nature of 4‐bromo‐3(5)‐methylpyrazoles. J Heterocycl Chem 2022. [DOI: 10.1002/jhet.4529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A. G. Aleksanyan
- Scientific Technological Center of Organic and Pharmaceutical Chemistry of NAS RA Yerevan Armenia
| | - R. M. Hakobyan
- Scientific Technological Center of Organic and Pharmaceutical Chemistry of NAS RA Yerevan Armenia
| | - A. G. Shahkhatuni
- Scientific Technological Center of Organic and Pharmaceutical Chemistry of NAS RA Yerevan Armenia
| | - A. A. Shahkhatuni
- Scientific Technological Center of Organic and Pharmaceutical Chemistry of NAS RA Yerevan Armenia
| | - H. S. Attaryan
- Scientific Technological Center of Organic and Pharmaceutical Chemistry of NAS RA Yerevan Armenia
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