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1.
J Phys Chem A ; 124(19): 3865-3875, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32285672

RESUMO

A broad series of quinoxalinone-based π-conjugated donor-acceptor fluoro- and NLO-phores is characterized by means of Raman spectroscopy and single-crystal X-ray analysis supported by quantum chemical computations. Intense Raman spectroscopic markers that allow the differentiation of even closely related structures are identified. The intensities of these bands are shown to be related to the conjugation of the different molecular moieties, and they can provide an estimation of its extent. The intensity redistribution between these markers serves as a source of auxiliary structural information capable of pointing to a distortion of the conjugation or to the influence of aggregation effects in the condensed state. A simple relation between the intensity of the marker and the position and oscillator strength of the lowest-energy electronic absorption band of quinoxalinones allows a linking of the Raman effect with the optical properties of these compounds, which can be used for the rational design of novel species with improved optical characteristics.

2.
Dalton Trans ; 49(2): 482-491, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31833494

RESUMO

In this work, we present the synthesis, structural and photophysical characterization, and theoretical study of tetranuclear copper(i) cubane-type Cu4I4 clusters 6-10 with different 10-(aryl)phenoxarsine ligands - 10-(p-fluorophenyl)phenoxarsine (1), 10-(p-ethoxyphenyl)phenoxarsine (2), 10-(phenyl)phenoxarsine (3), 10-(m-fluorophenyl)phenoxarsine (4), and 10-(o-methoxyphenyl)phenoxarsine (5), respectively. The structures of 1-5 were confirmed by NMR spectroscopy, mass spectrometry, elemental analysis and for complexes 6, 7, and 10 by single-crystal X-ray diffraction analysis. The UV/Vis absorption and emission properties were studied and rationalized by DFT and time-dependent DFT calculations. In the solid state, under UV irradiation, all complexes exhibit an intense green emission, which was attributed to a cluster-centered triplet state.

3.
Bioorg Med Chem Lett ; 22(22): 6909-13, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-23046964

RESUMO

New derivatives of steviol 1, the aglycone of the glycosides of Stevia rebaudiana, including a novel class of semisynthetic diterpenoids, namely macrocyclic ent-kauranes were synthesized. These compounds possess antituberculosis activity inhibiting the in vitro growth of Mycobacterium Tuberculosis (H37R(V) strain) with MIC 5-20 µg/ml that is close to MIC 1 µg/ml demonstrated by antituberculosis drug isoniazid in control experiment. For the first time it was found that the change of ent-kaurane geometry (as in steviol 1) of tetracyclic diterpenoid skeleton to ent-beyerane one (as in isosteviol 2) influences on antituberculosis activity.


Assuntos
Antituberculosos/síntese química , Diterpenos de Caurano/química , Compostos Macrocíclicos/química , Antituberculosos/química , Antituberculosos/farmacologia , Cristalografia por Raios X , Diterpenos de Caurano/síntese química , Diterpenos de Caurano/farmacologia , Testes de Sensibilidade Microbiana , Conformação Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Stevia/química
4.
Chirality ; 21(7): 637-41, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18853466

RESUMO

Although racemic allylbenzylmethylphenylammonium iodide 1b displays spontaneous resolution crystallizing in a homochiral mode as a conglomerate, its phosphonium analogue rac-2b crystallizes in a heterochiral lattice forming racemic compound in the solid state. The more pronounced conformation freedom for 2b molecules manifests itself by multiple molecules crystallization (Z' = 3) of (S)-2b with the three independent molecules having different conformation.

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