The Lewis acidities of gold(I) and gold(III) derivatives: a theoretical study of complexes of AuCl and AuCl3

Chloride complexes of gold(I) (seventeen) and gold(III) (seventeen) with different ligands (including H, C, N, O, P, S as interacting atoms) have been studied at the CCSD(T)/CBS level. The computed geometries were compared with those found in the Cambridge Structural Database and the dissociation energies related with those previously reported in the literature by Yamamoto et al. Some special processes catalysed by these gold complexes such as bond-breaking (dihydrogen, cyclopropane) and arenes reactivity were studied in detail.

     

A Talenti Comparison Result for Solutions to Elliptic Problems with Robin Boundary Conditions

Comparison results of Talenti type for elliptic problems with Dirichlet boundary conditions have been widely investigated in recent decades. In this paper, we deal with Robin boundary conditions. Surprisingly, contrary to the Dirichlet case, Robin boundary conditions make the comparison sensitive to the dimension, and while the planar case seems to be completely settled, in higher dimensions some open problems are yet unsolved. © 2023 The Authors. Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC.     

A variational method for the calculation of spin-rovibronic energy levels of triatomic molecules with three interacting electronic states

A general method is presented for the evaluation of the spin rovibronic energy levels of triatomic molecules with up to three interacting potential energy surfaces. The full theory is outlined in detail, both for singlet and for doublet electronic states and the method is then applied to the benchmark example of C₂H. High quality multireference configuration interaction calculations have been carried out to generate the 3-dimensional near-equilibrium adiabatic potential energy surfaces of the three lowest 1²A'(X²Σ⁺), 2²A'(A²Π), 1²A''(A²Π) electronic states of C₂H, and the pair of interacting states of A 0 symmetry have then been diabatized. Results are presented for J up to 7/2 and compared with gas-phase high resolution experimental results for energies up to 5600 cm¹.     

Isoparametric submanifolds in two-dimensional complex space forms

We show that an isoparametric submanifold of a complex hyperbolic plane, according to the definition of Heintze, Liu and Olmos’, is an open part of a principal orbit of a polar action. We also show that there exists a non-isoparametric submanifold of the complex hyperbolic plane that is isoparametric according to the definition of Terng’s. Finally, we classify Terng-isoparametric submanifolds of two-dimensional complex space forms.     

Weakly <Emphasis Type="Italic">φ</Emphasis>-pairs and common fixed points in cone metric spaces

In this paper we introduce a weak contractive condition, called weakly φ-pair, for two mappings in the framework of cone metric spaces and we prove a theorem which ensures existence and uniqueness of common fixed points for such mappings. Also we obtain a result on points of coincidence. These results extend and generalize well-known comparable results in the literature. The authors are supported by Università degli Studi di Palermo, R. S. ex 60%.     

A Particle Filtering Approach for Tracking an Unknown Number of Objects with Dynamic Relations

In recent years there has been a growing interest on particle filters for solving tracking problems, thanks to their applicability to problems with continuous, non-linear and non-Gaussian state spaces, which makes them more suited than hidden Markov models, Kalman filters and their derivations, in many real world tasks. Applications include video surveillance, sensor fusion, tracking positions and behaviors of moving objects, situation assessment in civil and bellic scenarios, econometric and clinical data series analysis. In many environments it is possible to recognize classes of similar entities, like pedestrians or vehicles in a video surveillance system, or commodities in econometric. In this paper, a relational particle filter for tracking an unknown number of objects is presented which exploits possible interactions between objects to improve the quality of filtering. We will see that taking into account relations between objects will ease the tracking of objects in presence of occlusions and discontinuities in object dynamics. Experimental results on a benchmark data set are presented.     

Influence of stereoelectronic effects on the 1JC─F spin–spin coupling constant in fluorinated heterocyclic compounds

The Perlin effect and its analog for fluorinated compounds (the fluorine Perlin-like effect) manifest on one-bond C─H (C─F for the fluorine Perlin-like effect) spin–spin coupling constants (SSCCs) in six-membered rings. These effects can be useful to probe the stereochemistry (axial or equatorial) of the C─H and C─F bonds, respectively. The origin of these effects has been debatable in the literature as being due to hyperconjugative interactions, dipolar effects, and induced current density. Accordingly, a variety of model compounds has been used to probe such effects since the cyclohexanone carbonyl group and the endocyclic heteroatom lone pairs play different roles on the above-mentioned effects. Thus, the ¹J_C─F SSCC in fluorinated lactams and lactones were theoretically studied to gain further insight on the nature of the fluorine Perlin-like effect. In addition, because the intramolecular α-effect has recently gained attention for its importance in the reactivity and stereoelectronic interactions in peroxide compounds, some fluorinated 1,2-dioxanes and 1,2-dithianes were studied to evaluate the role of the α-effect on the behavior of ¹J_C─F SSCCs. Differently from fluorinated ketones and ethers, the fluorine Perlin-like effect in the amides and esters cannot be explained by hyperconjugative or dipolar interactions alone, because the resonance in these groups affect the ¹J_C─F values. The O─O and S─S-containing systems exhibit a strong fluorine Perlin-like effect, but unlike the α-effect, this behavior cannot be explained neither by hyperconjugation nor by dipolar interactions alone; the spatial proximity of the C─F and O─O/S─S bonds is proposed to affect the magnitude of the ¹J_C─F SSCC.     

Chemical Characterization and Bioactivity of Commercial Essential Oils and Hydrolates Obtained from Portuguese Forest Logging and Thinning

Essential oils (EOs) and hydrolates (Hds) are natural sources of biologically active ingredients with broad applications in the cosmetic industry. In this study, nationally produced (mainland Portugal and Azores archipelago) EOs (11) and Hds (7) obtained from forest logging and thinning of Eucalyptus globulus, Pinus pinaster, Pinus pinea and Cryptomeria japonica, were chemically evaluated, and their bioactivity and sensorial properties were assessed. EOs and Hd volatiles (HdVs) were analyzed by GC-FID and GC-MS. 1,8-Cineole was dominant in E. globulus EOs and HdVs, and α- and β-pinene in P. pinaster EOs. Limonene and α-pinene led in P. pinea and C. japonica EOs, respectively. P. pinaster and C. japonica HVs were dominated by α-terpineol and terpinen-4-ol, respectively. The antioxidant activity was determined by DPPH, ORAC and ROS. C. japonica EO showed the highest antioxidant activity, whereas one of the E. globulus EOs showed the lowest. Antimicrobial activity results revealed different levels of efficacy for Eucalyptus and Pinus EOs while C. japonica EO showed no antimicrobial activity against the selected strains. The perception and applicability of emulsions with 0.5% of EOs were evaluated through an in vivo sensory study. C. japonica emulsion, which has a fresh and earthy odour, was chosen as the most pleasant fragrance (60%), followed by P. pinea emulsion (53%). In summary, some of the studied EOs and Hds showed antioxidant and antimicrobial activities and they are possible candidates to address the consumers demand for more sustainable and responsibly sourced ingredients.