Dual descriptor and molecular electrostatic potential: complementary tools for the study of the coordination chemistry of ambiphilic ligands

The possibility to retrieve the coordinating properties of ligands by a combined dual descriptor and molecular electrostatic potential analysis is shown, yielding a potentially predictive tool of their ambiphilicity and selectivity.

Enantiomeric differentiation of aromatic amino acids using traveling wave ion mobility-mass spectrometry

The present work describes the first differentiation of amino acids enantiomers using the coupling of traveling wave ion mobility and mass spectrometry.

Role of cationization and multimers formation for diastereomers differentiation by ion mobility-mass spectrometry

Stereochemistry plays an important role in biochemistry, particularly in therapeutic applications. Indeed, enantiomers have different biological activities, which can have important consequences. Many analytical techniques have been developed in order to allow the identification and the separation of stereoisomers. Here, we focused our work on the study of small diastereomers using the coupling of traveling wave ion mobility and mass spectrometry (TWIMS-MS) as a new alternative for stereochemistry study. In order to optimize the separation, the formation of adducts between diastereomers (M) and different alkali cations (X) was carried out. Thus, monomers [M + X](+) and multimers [2M + X](+) and [3M + X](+) ions have been studied from both experimental and theoretical viewpoints. Moreover, it has been shown that the study of the multimer [2Y + M + Li](+) ion, in which Y is an auxiliary diastereomeric ligand, allows the diastereomers separation. The combination of cationization, multimers ions formation, and IM-MS is a novel and powerful approach for the diastereomers identification. Thus, by this technique, diastereomers can be identified although they present very close conformations in gaseous phase. This work presents the first TWIMS-MS separation of diastereomers, which present very close collision cross section thanks to the formation of multimers and the use of an auxiliary diastereomeric ligand.

On the physical role of exchange in the formation of an intramolecular bond path between two electronegative atoms

In this paper, we present a detailed energetic decomposition of intramolecular O···X interactions (X being O, S, or a halogen atom) based on the interacting quantum atoms approach of Pendás and co-workers. The nature of these interactions (repulsive or attractive, more or less electrostatic) is discussed in the framework of Bader's atoms in molecules theory, a particular emphasis being put on delocalization (measured by delocalization indexes and in terms of the source function) and on the exchange contributions. Notably, the concept of exchange channels introduced by Pendás and collaborators provides means of rationalizing and predicting the presence of bond critical points, enhancing the physical meaning of bond paths.

An evaluation of the effect of an educational intervention for Australian social workers on competence in delivering brief cognitive behavioural strategies: a randomised controlled trial

Background

Broad community access to high quality evidence-based primary mental health care is an ongoing challenge around the world. In Australia one approach has been to broaden access to care by funding psychologists and other allied health care professionals to deliver brief psychological treatments to general practitioners' patients. To date, there has been a scarcity of studies assessing the efficacy of social worker delivered psychological strategies. This study aims to build the evidence base by evaluating the impact of a brief educational intervention on social workers' competence in delivering cognitive behavioural strategies (strategies derived from cognitive behavioural therapy).

Methods

A randomised controlled trial design was undertaken with baseline and one-week follow-up measurement of both objective and self-perceived competence. Simulated consultations with standardised depressed patients were recorded on videotape and objective competence was assessed by blinded reviewers using the Cognitive Therapy Scale. Questionnaires completed by participants were used to measure self-perceived competence. The training intervention was a 15 hour face-to-face course involving presentations, video example consultations, written materials and rehearsal of skills in pairs.

Results

40 Melbourne-based (Australia) social workers enrolled and were randomised and 9 of these withdrew from the study before the pre training simulated consultation. 30 of the remaining 31 social workers (97%) completed all phases of the intervention and evaluation protocol (16 from intervention and 14 from control group). The intervention group showed significantly greater improvements than the control group in objective competence (mean improvement of 14.2 (7.38-21.02) on the 66 point Cognitive Therapy Scale) and in subjective confidence (mean improvement of 1.28 (0.84-1.72) on a 5 point Likert scale). On average, the intervention group improved from below to above the base competency threshold on the Cognitive Therapy Scale whilst the control group remained below.

Conclusions

Social workers can attain significant improvements in competency in delivering cognitive behavioural strategies from undertaking brief face to face training. This is relevant in the context of health reforms that involve social worker delivery of evidence based psychological care. Further research is required to assess how these improvements in competence translate into performance in practice and clinical outcomes for patients.

QSPR modeling of thermal stability of nitroaromatic compounds: DFT vs. AM1 calculated descriptors

The quantitative structure-property relationship (QSPR) methodology was applied to predict the decomposition enthalpies of 22 nitroaromatic compounds, used as indicators of thermal stability. An extended series of descriptors (constitutional, topological, geometrical charge related and quantum chemical) was calculated at two different levels of theory: density functional theory (DFT) and semi-empirical AM1 approaches. Reliable models have been developed for each level, leading to similar correlations between calculated and experimental data (R(2) > 0.98). Hence, both of them can be employed as screening tools for the prediction of thermal stability of nitroaromatic compounds. If using the AM1 model presents the advantage to be less time consuming, DFT allows the calculation of more accurate molecular quantum properties, e.g., conceptual DFT descriptors. In this study, our best QSPR model is based on such descriptors, providing more chemical comprehensive relationships with decomposition reactivity, a particularly complex property for the specific class of nitroaromatic compounds.

On the prediction of thermal stability of nitroaromatic compounds using quantum chemical calculations

This work presents a new approach to predict thermal stability of nitroaromatic compounds based on quantum chemical calculations and on quantitative structure-property relationship (QSPR) methods. The data set consists of 22 nitroaromatic compounds of known decomposition enthalpy (taken as a macroscopic property related to explosibility) obtained from differential scanning calorimetry. Geometric, electronic and energetic descriptors have been selected and computed using density functional theory (DFT) calculation to describe the 22 molecules. First approach consisted in looking at their linear correlations with the experimental decomposition enthalpy. Molecular weight, electrophilicity index, electron affinity and oxygen balance appeared as the most correlated descriptors (respectively R(2)=0.76, 0.75, 0.71 and 0.64). Then multilinear regression was computed with these descriptors. The obtained model is a six-parameter equation containing descriptors all issued from quantum chemical calculations. The prediction is satisfactory with a correlation coefficient R(2) of 0.91 and a predictivity coefficient R(cv)(2) of 0.84 using a cross validation method.