Multivariate characterisation and quantitative structure–property relationship modelling of nitroaromatic compounds

Combined Toxicity of Nitro-Substituted Benzenes and Zinc to Photobacterium Phosphoreum: Evaluation and QSAR Analysis

The single toxicity (IC₅₀) of zinc (Zn) and 11 nitro-substituted benzenes to Photobacterium phosphoreum were determined, respectively. On basis of single toxicity, the joint toxicity of binary mixtures of Zn and 11 nitro-substituted benzenes at different Zn concentrations of 0.2 IC₅₀, 0.5 IC₅₀, and 0.8 IC₅₀ were measured. The joint toxicity was evaluated by toxic unit (TU) and additive index (AI) methods. The results indicated that the joint toxicity was not only depending on the Zn concentrations but also on the substituted groups of nitro-substituted benzenes. The quantitative structure-activity relation (QSAR) equations were developed and the results showed that the toxicity of nitro-substituted benzenes has different joint effect at the different Zn concentrations. At the Zn concentration of 0.2 IC₅₀, the binary joint effects were mainly antagonism and the joint toxicity was negatively related to descriptors called VE2_B(p) and TIC3. At the Zn concentration of 0.5 IC₅₀ and 0.8 IC₅₀, the binary joint effects were mainly antagonism and simple addition, and the joint toxicity was related to the same descriptor Eig06_ AEA(dm). It indicated that the joint toxic actions were similar when combined at the medium and high concentrations of Zn.

An integrated computational protocol for the accurate prediction of EPR and PNMR parameters of aminoxyl radicals in solution

Magnetic spectroscopic techniques such as electron paramagnetic resonance (EPR) and paramagnetic NMR (PNMR) are valuable tools for understanding the structure and dynamics of complex systems such as, for example, biomolecules or nanomaterials labeled with suitable free radicals. Unfortunately, such spectra do not give direct access to the radical structure because of the subtle interplay between several different effects not easily separable and evaluable by experimentalists alone. In this respect, computational spectroscopy is becoming an essential and versatile tool for the assignment and interpretation of experimental spectra. In this article, the new integrated computational approaches developed in the recent years in our research group are reviewed. Such approaches have been applied to two widely used spin probes showing that proper account of stereo-electronic, environmental and dynamical effects leads to magnetic properties in remarkable agreement with experimental results.