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1.
Phys Chem Chem Phys ; 24(4): 2349-2356, 2022 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-35018905

RESUMO

By employing diverse surface sensitive synchrotron radiation spectroscopies we demonstrate that the fluorine content of initial C60F48 deposited at room temperature on Ag(111) varies with molecular coverage. At the very early stages of deposition, C60F48 fully de-fluorinates and transforms into C60. Strong indications of silver fluoride formation are provided. The chemical footprint of fluorinated fullerenes emerges at relatively low molecular coverage indicating that the degree of fullerene de-fluorination decreases (from total to partial de-fluorination) as molecules are deposited. Full de-fluorination stops well before the substrate surface is completely covered by fullerenes. At the molecular level, the fluorine loss observed by spectroscopic techniques is supported by scanning tunneling microscopy imaging. Both molecules and metal surface are importantly involved in the process.

2.
Phys Chem Chem Phys ; 23(41): 23517-23525, 2021 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-34642728

RESUMO

The electronic properties of a diboron molecule, namely bis(catecholato)diboron (2-(1,3,2-benzodioxaborol-2-yl)-1,3,2-benzodioxaborole) (B2Cat2), have been studied by comparing the results of photoemission (XPS) and near edge X-ray absorption spectroscopy (NEXAFS) experiments with the outcome of DFT calculations. The B 1s, C 1s and O 1s K-edges have been investigated for both the isolated gas phase molecule and the adsorbed one on the Au(111) surface. The main features of the polarized NEXAFS spectra at each of the three edges considered are not significantly affected by the presence of the substrate, with respect to the isolated molecule, indicating that the molecule-gold interaction is weak. Moreover, the comparison between the observed dichroism in the NEXAFS spectra of the adsorbed B2Cat2 and that in the NEXAFS spectra of the isolated molecule has confirmed the orbital symmetry assigned in the gas phase absorption spectra. The transitions to π(B-B) bonding and π*(B-B) anti-bonding final states represent the most relevant probe of the chemistry of the B2Cat2 molecule. We show that their theoretical description requires that the treatment of the relaxation changes among different excited state configurations, which we successfully implemented by using ΔSCF-DFT (ΔSCF) calculations.

3.
Bioorg Med Chem Lett ; 11(11): 1461-4, 2001 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-11378377

RESUMO

A novel series of novobiocin analogues has been synthesised by removing the lipophilic aryl chain in novobiocin and introducing an amino substituent. The structural modifications have been dictated by the control of lipophilicity and the dissociation constant of the resulting compounds. Antibacterial activity of the new coumarin derivatives could be correlated with the amount of uncharged form in physiological conditions.


Assuntos
Antibacterianos/síntese química , Novobiocina/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Cumarínicos/química , Testes de Sensibilidade Microbiana , Novobiocina/análogos & derivados , Novobiocina/química , Novobiocina/farmacologia , Staphylococcus aureus/efeitos dos fármacos
4.
Bioorg Med Chem Lett ; 9(19): 2875-80, 1999 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-10522710

RESUMO

Two series of aminosubstituted coumarins were synthesised and evaluated in vitro as inhibitors of DNA gyrase and as potential antibacterials. Novel novobiocin-like coumarins, 4-(dialkylamino)methylcoumarins and 4-((2-alkylamino)ethoxy)coumarins, were discovered as gyrase B inhibitors with promising antibacterial activity in vitro.


Assuntos
Cumarínicos/síntese química , Inibidores da Topoisomerase II , Antibacterianos/síntese química , Antibacterianos/farmacologia , Cumarínicos/farmacologia , DNA Girase , DNA Super-Helicoidal/metabolismo , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Escherichia coli/enzimologia , Bactérias Gram-Positivas/efeitos dos fármacos , Estrutura Molecular , Novobiocina/análogos & derivados , Novobiocina/farmacologia , Peptídeos Cíclicos/farmacologia , Relação Estrutura-Atividade
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