Luminescence enhancement and tuning via multiple cooperative supramolecular interactions in an ion-paired multinuclear complex

[(3,5-(CF(3))(2)Pz)(AgL)(2)](+)[Ag(5)(3,5-(CF(3))(2)Pz)(6)(CH(3)CN)](-) (L = 2-(N,N-diethylanilino-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine) shows bright and tunable emissions influenced by its supramolecular structure. Columnar stacks are assembled via cooperative interactions that include Ag(I)···Ag(I) argentophilic bonding, π···π stacking and Ag(I)···π interactions.     

Layered ionic liquid-crystalline organisations built from nano-capsules [Mo132O312S60(SO4)x(H2O)132−2x](12 + 2x)− and DODA+ cations

Two dimethyldioctadecylammonium (DODA⁺) salts of a new keplerate with the general formula [Mo₁₃₂O₃₁₂S₆₀(SO₄)_x(H₂O)_132–2x]^{(12 + 2x)?} and abbreviated DODA_n?Mo₁₃₂S₆₀ (n = 44, 56) were synthesised and characterised. Both clusters were fully characterised by the combination of Polarised Optical Microscopy, Differential Scanning Calorimetry and Small-angle X-Ray Diffraction showing self-organisation in lamellar (L) liquid crystalline phases. We demonstrated that the lamellar periodicity h of the mesophases can be controlled with the number of DODA⁺ associated to the clusters. Finally, these new results were compared to those gained from a previously published analogue, the fully oxo keplerate noted DODA₃₆?Mo₁₃₂ that also self-organise with temperature, but in a slightly more structured lamellar liquid crystalline phase.     

Anomalous structure-luminescence relationship in phosphorescent gold(I) isonitrile neutral complexes

A new compound that exhibits the shortest intermolecular Au...Au distance ever reported for neutral RNCAuX complexes is found to exhibit a counterintuitive higher-energy Au-centered phosphorescence than that in an analogous compound with a much longer Au...Au distance, presumably due to a different extent of excited-state distortion in dimers vs. extended chains.     

Synthesis, spectral and structural characterization of dinuclear rhodium (II) complexes of the anticonvulsant drug valproate with theophylline and caffeine

The dinuclear complex tetra(μ-valproato) dirhodium(II), Rh₂(valp)₄ (1), and its bis-adducts with theophylline, Rh₂(valp)₄(ThH)₂ (4), or caffeine, Rh₂(valp)₄(Caf)₂ (5), have been synthesized and characterized by elemental analysis, IR, UV-Vis, magnetic moment, ¹H and ¹³C NMR spectroscopic techniques. Spectral data for the complexes are consistent with a dinuclear structure as found for rhodium (II) tetracarboxylate adducts. Theophylline and caffeine bases in complexes 4 and 5, respectively, are axially coordinated to rhodium (II) atoms through the sterically hindered N(9) site. This is confirmed by X-ray crystal structure analyses of complexes 4 and 5.     

Solvent-ligated copper(II) complexes for the homopolymerization of 2-methylpropene

Copper(II) complexes with weakly coordinating counter anions can be utilized as highly efficient catalysts for the synthesis of poly(2-methylpropene) ("polyisobutene") with a high content of terminal double bonds. These copper(II) compounds are significantly more active than the manganese(II) complexes described previously, can be applied in chlorine-free solvents such as toluene, are easily accessible, and can be handled at room temperature and in laboratory atmospheres for brief periods, but they are sensitive to excess water, thereby losing their catalytic activity. Replacing the acetonitrile ligands by benzonitrile ligands improves the solubility and catalytic activity in nonpolar and nonchlorinated solvents. However, the benzonitrile copper(II) compounds have lower thermal stability than their acetonitrile congeners.     

Phase Transitions in Transfer Learning for High-Dimensional Perceptrons

Transfer learning seeks to improve the generalization performance of a target task by exploiting the knowledge learned from a related source task. Central questions include deciding what information one should transfer and when transfer can be beneficial. The latter question is related to the so-called negative transfer phenomenon, where the transferred source information actually reduces the generalization performance of the target task. This happens when the two tasks are sufficiently dissimilar. In this paper, we present a theoretical analysis of transfer learning by studying a pair of related perceptron learning tasks. Despite the simplicity of our model, it reproduces several key phenomena observed in practice. Specifically, our asymptotic analysis reveals a phase transition from negative transfer to positive transfer as the similarity of the two tasks moves past a well-defined threshold.     

Synthesis and Analysis of Substituted Bullvalenes

Herein we detail a practical synthesis of bullvalene and a variety of mono‐ and disubstituted analogues through cobalt‐catalysed [6+2] cycloaddition of cyclooctatetraene to alkynes, followed by photochemical di‐π‐methane rearrangement. The application of isomer‐network analysis, coupled with quantum‐chemical calculations, provides a powerful automated tool for predicting the properties of bullvalene isomer networks.     

A discriminant method for classification of Moroccan olive varieties by using direct FT-IR analysis of the mesocarp section

Four cultivars of olives picked up in the Moroccan region of Beni Mellal were subjected to a characterization and classification study. Analytical data were collected by Fourier transform infrared spectroscopy (FTIR), applied on the mesocarp of the fresh olives without any preliminary treatment. The spectral data were pre-treated by derivative elaboration based on the Savitzky-Golay algorithm to reduce noise and increase analytical information. Partial least squares discriminant analysis (PLS-DA) was performed to elaborate the measurement data and assess the discriminant features of the four cultivars. The PLS model was optimized by applying the Martens’ uncertainty test which provided to select the vibrational frequencies giving the most useful information. The optimized model resulted able to separate the four classes and classify new objects into the appropriate defined classes with a percentage prediction of 97%. The proposed method represents a real novelty to classify olives of different varieties by means of a rapid, inexpensive and reliable procedure.