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Selegato, Denise Medeiros; Freire, Rafael Teixeira; Pilon, Alan César; Biasetto, Carolina Rabal; Oliveira, Haroldo Cesar; Abreu, Lucas Magalhães; Araujo, Angela Regina; Silva Bolzani, Vanderlan; Castro‐Gamboa, Ian
doi: 10.1002/mrc.4874pmid: 30993742
Traditionally, the screening of metabolites in microbial matrices is performed by monocultures. Nonetheless, the absence of biotic and abiotic interactions generally observed in nature still limit the chemical diversity and leads to “poorer” chemical profiles. Nowadays, several methods have been developed to determine the conditions under which cryptic genes are activated, in an attempt to induce these silenced biosynthetic pathways. Among those, the one strain, many compounds (OSMAC) strategy has been applied to enhance metabolic production by a systematic variation of growth parameters. The complexity of the chemical profiles from OSMAC experiments has required increasingly robust and accurate techniques. In this sense, deconvolution‐based 1HNMR quantification have emerged as a promising methodology to decrease complexity and provide a comprehensive perspective for metabolomics studies. Our present work shows an integrated strategy for the increased production and rapid quantification of compounds from microbial sources. Specifically, an OSMAC design of experiments (DoE) was used to optimize the microbial production of bioactive fusaric acid, cytochalasin D and 3‐nitropropionic acid, and Global Spectral Deconvolution (GSD)‐based 1HNMR quantification was carried out for their measurement. The results showed that OSMAC increased the production of the metabolites by up to 33% and that GSD was able to extract accurate NMR integrals even in heavily coalescence spectral regions. Moreover, GSD‐1HNMR quantification was reproducible for all species and exhibited validated results that were more selective and accurate than comparative methods. Overall, this strategy up‐regulated important metabolites using a reduced number of experiments and provided fast analyte monitor directly in raw extracts.
Chapyshev, Sergei V.; Korchagin, Denis V.; Grote, Dirk; Sander, Wolfram
doi: 10.1002/mrc.4877pmid: 30997697
Complex multicomponent, multispin molecular system, consisting of a septet trinitrene, two quintet dinitrenes, and three triplet mononitrenes, was obtained by the photolysis of 2,4,6‐triazido‐3‐cyano‐5‐fluoropyridine in solid argon. To identify these paramagnetic products, electron paramagnetic resonance spectroscopy in combination with line‐shape spectral simulations and density functional theory calculations was used. The products of the photolysis was found to be triplet 2,4‐diazido‐3‐cyano‐5‐fluoropyridyl‐6‐nitrene (DT = 1.000 cm−1, ET = 0), triplet 2,4‐diazido‐3‐cyano‐5‐fluoropyridyl‐2‐nitrene (DT = 1.043 cm−1, ET = 0), triplet 2,6‐diazido‐3‐cyano‐5‐fluoropyridyl‐4‐nitrene (DT = 1.128 cm−1, ET = 0 cm−1), quintet 4‐azido‐3‐cyano‐5‐fluoropyridyl‐2,6‐dinitrene (DQ = 0.211 cm−1, EQ = 0.0532 cm−1), quintet 2‐azido‐3‐cyano‐5‐fluoropyridyl‐4,6‐dinitrene (DQ = 0.208 cm−1, EQ = 0.0386 cm−1), and septet 3‐cyano‐5‐fluoropyridyl‐2,4,6‐trinitrene (DS = −0.1017 cm−1, ES = −0.0042 cm−1) in a 38:4:7:22:14:4 ratio, respectively.
doi: 10.1002/mrc.4878pmid: 31017688
The (C7H12N2)2[SnCl6]Cl2·1.5H2O complex is a new member of the family of hybrid organic–inorganic perovskite compounds. It exhibits two order–disorder phase transitions with changes in the conformation of aromatic cations at the two transition temperatures 360 and 412 K. Differential scanning calorimetry, nuclear magnetic resonance (NMR), and Fourier‐transform infrared (FT‐IR) spectroscopy were used to investigate these phase transitions. These transition mechanisms were investigated in terms of the spin–lattice relaxation times T1 for 1H static NMR and the chemical shifts for 13C CP–MAS. The temperature dependence of T1(1H) and 13C chemical shifts are changed near TC1 and TC2. Furthermore, the splitting for 13C NMR signals in Phases (II) and (III) indicated a ferroelastic characteristic of the compound. In addition, FT‐IR results indicate that the ordered conformational structure of aromatic cations undergoes a remarkable disorder with increasing temperature. The NMR and FT‐IR studies suggest that the phase transition mechanisms are related to the reorientational motion of [C7H12N2]2+ cations as a whole. Phase transition was examined in light of the interesting optical properties of this material.
Kupka, Teobald; Mnich, Adrianna; Broda, Małgorzata A.
doi: 10.1002/mrc.4879pmid: 31013546
Nuclear shieldings and chemical shifts of 5‐fluorocytosine (5FC) were predicted in the gas phase and DMSO solution modeled by polarizable continuum model using B3LYP density functional and revised STO(1M)‐3G basis set. For comparison, eight arbitrary selected basis sets including STO‐3G and medium‐size Pople‐type and larger dedicated Jensen‐type ones were applied. The former basis sets were significantly smaller, but the calculated structural parameters, harmonic vibrational frequencies, were very accurate and close to those obtained with larger, polarization‐consistent ones. The predicted 13C and 1H chemical shieldings of 5FC and cytosine, selected as parent molecule, were acceptable (root mean square for 13C chemical shifts in DMSO of about 5 ppm and less) though less accurate than those calculated with large basis sets, dedicated for prediction of nuclear magnetic resonance parameters.
Ramu, Loganathan; Kuppan, Narendra; Ramesh, Keralapura Parthasarathy; Chandramani, Rattihalli; Ramananda, Daivagna
doi: 10.1002/mrc.4881pmid: 31038234
35Cl NQR frequency and spin lattice relaxation time in 3,4‐dichloronitrobenzene have been measured as a function of temperature and pressure. Two NQR signals were observed in the temperature range 77 to 300 K and pressure up to 5.1 kbar at 300 K. The contributions to the relaxation from the torsional motion of the molecule and reorientational motion of the nitro group have been analyzed on the basis of the Woessner and Gutowsky model. The temperature dependence of the average torsional lifetimes of the molecules, transition probabilities, and the activation energy for the reorientation of the nitro group was estimated.
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