In this study, in order to explain the solvent and spin state effects on the molecular structure of catechol-Fe complex [Fe(cat)3]n﹣?where n = 2 and 3, Hartree Fock (HF)-Density Functional Theory (DFT) hybrid calcula...In this study, in order to explain the solvent and spin state effects on the molecular structure of catechol-Fe complex [Fe(cat)3]n﹣?where n = 2 and 3, Hartree Fock (HF)-Density Functional Theory (DFT) hybrid calculations are performed at the B3LYP/6-311g(d,p) level of theory. The binding energies of Fe2+ and Fe3+ in high-spin state are higher than intermediate and low-spin states which show that the complex formation in a high spin state is more favorable. The calculated binding energies at different solvents indicate that the binding energies in polar solvents are lower than non-polar solvents. Furthermore, spectroscopic studies including FTIR and Raman spectrum in various solvents reveal that the formation of intermolecular bonds between the oxygen atom of carbonyl group and the hydrogen atom of solvent causes a spectral red shift. The calculated FTIR and geometry parameters are in good agreement with previous experimental data. Donor-acceptor interaction energies are evaluated due to the importance of the charge transfer in the complex formation. It is observed that the free electrons of oxygen atom interact with the antibonding orbitals of the iron. Finally, some correlations between the quantum chemical reactivity indices of the complexes and solvent polarity are considered. The study indicates a linear correlation between chemical hardness and binding energies of [Fe(cat)3]3﹣?complex.展开更多
Bacillus amyloliquefaciens is a biocontrol agent whose genome has been sequenced. Within the genome of B. amyloliquefaciens are genes associated with iron chelation, but these genes are not found within all sequenced ...Bacillus amyloliquefaciens is a biocontrol agent whose genome has been sequenced. Within the genome of B. amyloliquefaciens are genes associated with iron chelation, but these genes are not found within all sequenced strains. The impact of iron availability on the B. amyloliquefaciens physiology was examined in this study. B. amyloliquefaciens ATCC 23843 was cultured under ironreplete and iron-deplete conditions for 48 hours, at 37°C. Final growth yields were dependent on iron concentration. Cultures grown in the absence of detectable iron were restricted in growth, but reached their highest yields at 48 hours. Iron restriction was confirmed by the presence of iron chelators in the filtrates. In contrast, B. amyloliquefaciens ATCC 23843 cultures grown with ferric ammonium citrate as the iron source research reached the highest yields at 24 hours. Iron chelator production was not detected in the ferric ammonium samples. A significant decrease in turbidity was observed for these cultures, which coincided with elevated spore production in B. amyloliquefaciens ATCC 23843. A decrease in turbidity was also observed on blood agar, where hemolysis was readily evident. We propose that iron impacts numerous physiological responses and further studies will elucidate the complex regulatory mechanisms governed by iron availability.展开更多
An iron（Ⅲ） complex [Fe^Ⅲ（Tpz^Me2）（Hpz^Me2）Cl2]（1） has been synthesized at a low temperature, which contains tripodal ligand, namely, the anionic hydrotris-3,5-dimethyl-pyrazolylborate（Tpz^Me2）. A series of...An iron（Ⅲ） complex [Fe^Ⅲ（Tpz^Me2）（Hpz^Me2）Cl2]（1） has been synthesized at a low temperature, which contains tripodal ligand, namely, the anionic hydrotris-3,5-dimethyl-pyrazolylborate（Tpz^Me2）. A series of iron（Ⅲ） catecholate complexes 2-5 has been obtained via the reaction of compound 1 with catecholate or substituted catecholates. These complexes were characterized by X-ray crystallographic analysis, mass spectrometry and elemental analysis, and the results show that TpzMe2 ligand has the beneficial effect on the stabilization of iron（Ⅲ） catecholate complexes.展开更多
文摘In this study, in order to explain the solvent and spin state effects on the molecular structure of catechol-Fe complex [Fe(cat)3]n﹣?where n = 2 and 3, Hartree Fock (HF)-Density Functional Theory (DFT) hybrid calculations are performed at the B3LYP/6-311g(d,p) level of theory. The binding energies of Fe2+ and Fe3+ in high-spin state are higher than intermediate and low-spin states which show that the complex formation in a high spin state is more favorable. The calculated binding energies at different solvents indicate that the binding energies in polar solvents are lower than non-polar solvents. Furthermore, spectroscopic studies including FTIR and Raman spectrum in various solvents reveal that the formation of intermolecular bonds between the oxygen atom of carbonyl group and the hydrogen atom of solvent causes a spectral red shift. The calculated FTIR and geometry parameters are in good agreement with previous experimental data. Donor-acceptor interaction energies are evaluated due to the importance of the charge transfer in the complex formation. It is observed that the free electrons of oxygen atom interact with the antibonding orbitals of the iron. Finally, some correlations between the quantum chemical reactivity indices of the complexes and solvent polarity are considered. The study indicates a linear correlation between chemical hardness and binding energies of [Fe(cat)3]3﹣?complex.
文摘Bacillus amyloliquefaciens is a biocontrol agent whose genome has been sequenced. Within the genome of B. amyloliquefaciens are genes associated with iron chelation, but these genes are not found within all sequenced strains. The impact of iron availability on the B. amyloliquefaciens physiology was examined in this study. B. amyloliquefaciens ATCC 23843 was cultured under ironreplete and iron-deplete conditions for 48 hours, at 37°C. Final growth yields were dependent on iron concentration. Cultures grown in the absence of detectable iron were restricted in growth, but reached their highest yields at 48 hours. Iron restriction was confirmed by the presence of iron chelators in the filtrates. In contrast, B. amyloliquefaciens ATCC 23843 cultures grown with ferric ammonium citrate as the iron source research reached the highest yields at 24 hours. Iron chelator production was not detected in the ferric ammonium samples. A significant decrease in turbidity was observed for these cultures, which coincided with elevated spore production in B. amyloliquefaciens ATCC 23843. A decrease in turbidity was also observed on blood agar, where hemolysis was readily evident. We propose that iron impacts numerous physiological responses and further studies will elucidate the complex regulatory mechanisms governed by iron availability.
基金Supported by the Natural Science Foundation of Inner Mongolia University for Nationalities, China(No.MDK2007036)
文摘An iron（Ⅲ） complex [Fe^Ⅲ（Tpz^Me2）（Hpz^Me2）Cl2]（1） has been synthesized at a low temperature, which contains tripodal ligand, namely, the anionic hydrotris-3,5-dimethyl-pyrazolylborate（Tpz^Me2）. A series of iron（Ⅲ） catecholate complexes 2-5 has been obtained via the reaction of compound 1 with catecholate or substituted catecholates. These complexes were characterized by X-ray crystallographic analysis, mass spectrometry and elemental analysis, and the results show that TpzMe2 ligand has the beneficial effect on the stabilization of iron（Ⅲ） catecholate complexes.
