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In this study, we used computational methods to investigate the interaction of amphetamine (AMP) with 1,2-indanedione (IND) and 1,8-diazafluoren-9-one (DFO) so as to understand whether AMP can be detected in latent fingerprints using either of these reagents. The results show that the binding energies of AMP with IND and DFO were enhanced by the presence of amino acid from -9.29 to -12.35 kcal mol -1 and -7.98 to -10.65 kcal mol -1 , respectively. The physical origins of these interactions could be better understood by symmetry-adapted perturbation theory. The excited state properties of the binding structures with IND demonstrate distinguishable absorption peaks in the UV-vis spectra but zero fluorescence. Furthermore, the UV-vis spectra of the possible reaction products between AMP and the reagents reveal absorption peaks in the visible spectrum. Therefore, we could predict that reaction of AMP with IND would be observable by a reddish colour while with DFO, a colour change to violet is expected. To conclude, the reagents IND and DFO may be used to detect AMP by UV-vis spectroscopy and if their reactions are allowed, the reagents may then act as a potentially rapid, affordable and easy colorimetric test for AMP in latent fingerprints without destruction of the fingerprint sample., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The role of cyclopropane substitution on the ethylene in zw-type [3+2] cycloaddition (32CA) reactions of cyclic nitrones has been studied within Molecular Electron Density Theory (MEDT) at the ω B97X-D/6-311G(d,p) computational level. Electron Localization Function (ELF) analysis of the ethylenes shows that the presence the cyclopropane only slightly increases the electron density in the C-C bonding region. Analysis of the Conceptual DFT reactivity indices indicates that the presence of the cyclopropane does not produce any remarkable change in the reactivity of these strained ethylenes. The marginal electrophilic character of ethylene makes the zw-type 32CA reactions of non-polar character. The presence of the cyclopropane in the ethylene decreases the activation enthalpy of the 32CA reactions by only 1.7 and 2.6 kcal mol -1 , and also decreases the ortho regioselectivity. The loss of the strain present in the cyclopropane is responsible for the reduction of the activation enthalpy and the increase of the reaction enthalpy in these non-polar 32CA reactions. The presence of the cyclopropane does not cause any change, neither in the transition state structure (TS) geometries nor in their electronic structure. The very low global electron density transfer (GEDT) computed at the TSs confirms the non-polar character of these 32CA reactions. The ortho regioselectivity experimentally observed in these non-polar 32CA reactions is determined by the most favorable two-center interaction between the less electronegative C1 carbon of nitrone and the non-substituted methylene C5 carbon of the ethylenes., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The proposed S N 2 reactions of a hindered organophosphorus reactant with aliphatic and aromatic nucleophiles [Ye et al. , Org. Lett. , 2017, 19 , 5384-5387] were studied theoretically in order to explain the observed stereochemistry of the products. Our computations (using B3LYP as the functional) indicate that the reaction with the aliphatic nucleophile occurs through a backside S N 2@P pathway while the reaction with the aromatic nucleophile proceeds through a novel S N 2@Cl mechanism, followed by a frontside S N 2@C mechanism., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A-234, [EtO-P([double bond, length as m-dash]O)(F)-N[double bond, length as m-dash]C(Me)-N(Et) 2 ], is the suspected A-type nerve agent used in the Skripal attack on the 4th of March 2018. Studies related to the structure and reactivity of this compound are limited. We, therefore, aimed at understanding the underlying hydrolysis mechanism of A-234 within the DFT framework. The attack of the water molecule can occur at the phosphinate and acetoamidine reactive centres. Our theoretical findings indicate that the hydrolysis at the acetoamidine centre is thermodynamically favoured compared to the hydrolysis at the phosphinate centre. The hydrolysis at the acetoamidine moiety may proceed via two pathways, depending on the nitrogen atom participating in the hydrolysis. The main pathway consists of four distinct channels to reach the final product, with the concerted 1,3-proton shift favoured kinetically and thermodynamically in the gas phase and water as solvent. The results are in good agreement with the literature, although some differences in the reaction mechanism were observed., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

A Molecular Electron Density Theory (MEDT) study of the regio- and stereoselectivity of the [3 + 2] cycloaddition (32CA) reaction of 1 H -phosphorinium-3-olate and 1-methylphosphorinium-3-olate with methyl methacrylate was carried out using the B3LYP/6-31G(d) method. In order to test the method dependence for the most favorable reaction path leading to the 1 H -substituted 6- exo cycloadduct (CA) various functionals using higher basis sets were taken into consideration in the gas phase. An analysis of the energetic parameters indicates that the reaction path leading to 6- exo CA are kinetically as well as thermodynamically favored in the gas phase, THF and ethanol. The calculated energetic parameters of the 32CA reaction of these phosphorus derivatives were compared with those of methyl acrylate and their nitrogen analogues. Investigation of the global electron density transfer at the TSs indicates that these 32CA reactions have non-polar character, while electron localisation function topological analysis of the C-C bond formation along the most favorable reaction path indicates that these 32CA reactions take place through a non-concerted two-stage one-step mechanism, via highly asynchronous TSs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A novel Pd-ZnO-expanded graphite (EG) photoelectrode was constructed from a Pd-ZnO-EG nanocomposite synthesised by a hydrothermal method and characterised using various techniques such as X-ray diffractometry (XRD), Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy, nitrogen adsorption-desorption analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Cyclic voltammetry and photocurrent response measurements were also carried out on the electrode. The Pd-ZnO-EG electrode was employed in the photoelectrocatalytic removal of 4-nitrophenol as a target water pollutant at a neutral pH and with a current density of 7 mA cm -2 . Optical studies revealed that the Pd-ZnO-EG absorbed strongly in the visible light region. The Pd-ZnO-EG electrode showed improved photoelectrocatalytic activity in relation to ZnO-EG and EG electrodes for the removal of the 4-nitrophenol. The photocurrent responses showed that the Pd-ZnO-EG nanocomposite electrode could be employed as a good photoelectrode for photoelectrocatalytic processes and environmental remediation such as treatment of industrial waste waters. Density functional theory method was used to model the oxidative degradation of 4-nitrophenol by the hydroxyl radical which generates hydroquinone, benzoquinone, 4-nitrocatechol, 4-nitroresorcinol and the opening of the 4-nitrophenol ring. Furthermore, the hydroxyl radical is regenerated and can further oxidise the ring structure and initiate a new degradation process., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)