Dataset Information

Complexes Between Adamantane Analogues B₄X₆ -X = {CH₂, NH, O ; SiH₂, PH, S} - and Dihydrogen, B₄X₆:nH₂ (n = 1-4).

ABSTRACT: In this work, we study the interactions between adamantane-like structures B₄X₆ with X = {CH₂, NH, O ; SiH₂, PH, S} and dihydrogen molecules above the Boron atom, with ab initio methods based on perturbation theory (MP2/aug-cc-pVDZ). Molecular electrostatic potentials (MESP) for optimized B₄X₆ systems, optimized geometries, and binding energies are reported for all B₄X₆:nH₂ (n = 1-4) complexes. All B₄X₆:nH₂ (n = 1-4) complexes show attractive patterns, with B₄O₆:nH₂ systems showing remarkable behavior with larger binding energies and smaller B···H₂ distances as compared to the other structures with different X.

SUBMITTER: Oliva-Enrich JM

PROVIDER: S-EPMC7179137 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Publications

Complexes Between Adamantane Analogues B4X6 -X = {CH2, NH, O ; SiH2, PH, S} - and Dihydrogen, B4X6:nH2 (n = 1-4).

Oliva-Enrich Josep M JM Alkorta Ibon I Elguero José J

Molecules (Basel, Switzerland) 20200226 5

In this work, we study the interactions between adamantane-like structures B4X6 with X = {CH2, NH, O ; SiH2, PH, S} and dihydrogen molecules above the Boron atom, with ab initio methods based on perturbation theory (MP2/aug-cc-pVDZ). Molecular electrostatic potentials (MESP) for optimized B4X6 systems, optimized geometries, and binding energies are reported for all B4X6:nH2 (n = 1-4) ...[more]

PMID: 32110922

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Project description:The titanocene sulfido complex Cp*(2)Ti(S)py (1, Cp* = pentamethylcyclopentadienyl; py = pyridine) is synthesized by addition of a suspension of S(8) to a toluene solution of Cp*(2)Ti-(CH(2)CH(2)) (2) and py. The rate of rotation of the pyridine ligand in solution was determined by (1)H NMR spectroscopy, and the structure of 1 was determined by X-ray crystallography. Complex 1 reacts reversibly with dihydrogen to give Cp*(2)Ti(H)SH (6) and py. Reaction of 1 with HD gives an equilibrium mixture of Cp*(2)Ti(D)SH and Cp*(2)Ti(H)SD; H(2) and D(2) are not formed in this reaction. 1D (1)H NMR magnetization transfer spectra and 2D EXSY (1)H NMR spectra of 6 in the presence of H(2) show that in solution the H(2), hydride, and hydrosulfido hydrogen atoms exchange. A four-center mechanism for this exchange is proposed. The EXSY studies show that the Ti-H and S-H hydrogens exchange with each other more rapidly than either of those hydrogens exchanges with external H(2). A transient dihydrogen complex intermediate is proposed to explain this observation. The infrared spectrum of 6 shows an absorption assigned to the Ti-H stretching mode at 1591 cm(-1) that shifts upon deuteration to 1154 cm(-1). Reaction of 1 with trimethylsilane, diethylsilane, or dimethylsilane gives Cp*(2)-Ti(H)SSiMe(3) (7), Cp*(2)Ti(H)SSiHEt(2) (8), or Cp*(2)Ti(H)SSiHMe(2) (9), respectively. The isotope effect for the reaction producing 7 has been measured, and a mechanism is proposed. Treatment of 1 with an additional equivalent of S(8) results in the formation of the disulfide Cp*(2)Ti(S(2)) (4). Acetylene inserts into the Ti-S bond of 4 to produce the vinyl disulfide complex 5. The structures of 4 and 5 have been determined by X-ray diffraction. Compound 4 reacts with 2 in the presence of py to produce 1. Phosphines react with 4 in the presence of H(2) to provide 6 and the corresponding phosphine sulfide. Reaction of hydrogen with 4 gives Cp*(2)-Ti(SH)(2) (3). The reactions of 1 and 4 with dihydrogen provide a model for possible mechanisms of H(2) activation by metal-sulfide hydrodesulfurization catalysts.

Project description:The treacherous nature of tuberculosis (TB) combined with the ubiquitous presence of the drug-resistant (DR) forms pose this disease as a growing public health menace. Therefore, it is imperative to develop new chemotherapeutic agents with a novel mechanism of action to circumvent the cross-resistance problems. The unique architecture of the Mycobacterium tuberculosis (M. tb) outer envelope plays a predominant role in its pathogenesis, contributing to its intrinsic resistance against available therapeutic agents. The mycobacterial membrane protein large 3 (MmpL3), which is a key player in forging the M. tb rigid cell wall, represents an emerging target for TB drug development. Several indole-2-carboxamides were previously identified in our group as potent anti-TB agents that act as inhibitor of MmpL3 transporter protein. Despite their highly potent in vitro activities, the lingering Achilles heel of these indoleamides can be ascribed to their high lipophilicity as well as low water solubility. In this study, we report our attempt to improve the aqueous solubility of these indole-2-carboxamides while maintaining an adequate lipophilicity to allow effective M. tb cell wall penetration. A more polar adamantanol moiety was incorporated into the framework of several indole-2-carboxamides, whereupon the corresponding analogues were tested for their anti-TB activity against drug-sensitive (DS) M. tb H37Rv strain. Three adamantanol derivatives 8i, 8j and 8l showed nearly 2- and 4-fold higher activity (MIC = 1.32 - 2.89 µM) than ethambutol (MIC = 4.89 µM). Remarkably, the most potent adamantanol analogue 8j demonstrated high selectivity towards DS and DR M. tb strains over mammalian cells [IC50 (Vero cells) ≥ 169 µM], evincing its lack of cytotoxicity. The top eight active compounds 8b, 8d, 8f, 8i, 8j, 8k, 8l and 10a retained their in vitro potency against DR M. tb strains and were docked into the MmpL3 active site. The most potent adamantanol/adamantane-based indoleamides 8j/8k displayed a two-fold surge in potency against extensively DR (XDR) M. tb strains with MIC values of 0.66 and 0.012 µM, respectively. The adamantanol-containing indole-2-carboxamides exhibited improved water solubility both in silico and experimentally, relative to the adamantane counterparts. Overall, the observed antimycobacterial and physicochemical profiles support the notion that adamantanol moiety is a suitable replacement to the adamantane scaffold within the series of indole-2-carboxamide-based MmpL3 inhibitors.

Dataset Information

Complexes Between Adamantane Analogues B₄X₆ -X = {CH₂, NH, O ; SiH₂, PH, S} - and Dihydrogen, B₄X₆:nH₂ (n = 1-4).

Publications

Complexes Between Adamantane Analogues B<sub>4</sub>X<sub>6</sub> -X = {CH<sub>2</sub>, NH, O ; SiH<sub>2</sub>, PH, S} - and Dihydrogen, B<sub>4</sub>X<sub>6</sub>:<i>n</i>H<sub>2</sub> (<i>n</i> = 1-4).

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