Nonlinear dimensionality reduction for visualizing toxicity data: Distance-based versus topology-based approaches.

Over the years, a number of dimensionality reduction techniques have been proposed and used in chemoinformatics to perform nonlinear mappings. In this study, four representatives of nonlinear dimensionality reduction methods related to two different families were analyzed: distance-based approaches (Isomap and Diffusion Maps) and topology-based approaches (Generative Topographic Mapping (GTM) and Laplacian Eigenmaps). The considered methods were applied for the visualization of three toxicity datasets by using four sets of descriptors. Two methods, GTM and Diffusion Maps, were identified as the best approaches, which thus made it impossible to prioritize a single family of the considered dimensionality reduction methods. The intrinsic dimensionality assessment of data was performed by using the Maximum Likelihood Estimation. It was observed that descriptor sets with a higher intrinsic dimensionality contributed maps of lower quality. A new statistical coefficient, which combines two previously known ones, was proposed to automatically rank the maps. Instead of relying on one of the best methods, we propose to automatically generate maps with different parameter values for different descriptor sets. By following this procedure, the maps with the highest values of the introduced statistical coefficient can be automatically selected and used as a starting point for visual inspection by the user

Application of Metal Phthalocyanine complexes to Carbene Transfer to N-H Bonds and Olefins

SSCI-VIDE+CDFA+LCL:ASOInternational audienceCarbene transfer to olefins and X-H bonds via α-diazocarbonyl precursor decomposition is a useful tool to build potentially biologically relevant elaborated molecules. Among metal complexes, metalloporphyrins have been extensively studied as catalysts for carbene transfer reactions. In contrast, their phthalocyanine counterparts have been used rarely but their utilization as catalyst for the elaboration of complex molecules is a growing area of interest.Here we present the novel use of binuclear Ruthenium(IV) phthalocyanine and Iron(III) phthalocyaninate bearing crown ether substituents as catalysts for the insertion of carbene formed from ethyl diazoacetate precursor into N-H bonds. Ruthenium(IV) phthalocyanine was also studied for the first time for intermolecular cyclopropanation of various olefins. With [(15C5)4PcFe]Cl as a catalyst for the synthesis of new class of ethyl glycinate amino acid derivatives, turnover numbers up to 3360 have been achieved. 36 – 69 % yields were obtained in the case of single N-H insertion products and up to 77 % in the case of double N-H insertion products

Application of Metal Phthalocyanine complexes to Carbene Transfer to N-H Bonds and Olefins

SSCI-VIDE+CDFA+LCL:ASOInternational audienceCarbene transfer to olefins and X-H bonds via α-diazocarbonyl precursor decomposition is a useful tool to build potentially biologically relevant elaborated molecules. Among metal complexes, metalloporphyrins have been extensively studied as catalysts for carbene transfer reactions. In contrast, their phthalocyanine counterparts have been used rarely but their utilization as catalyst for the elaboration of complex molecules is a growing area of interest.Here we present the novel use of binuclear Ruthenium(IV) phthalocyanine and Iron(III) phthalocyaninate bearing crown ether substituents as catalysts for the insertion of carbene formed from ethyl diazoacetate precursor into N-H bonds. Ruthenium(IV) phthalocyanine was also studied for the first time for intermolecular cyclopropanation of various olefins. With [(15C5)4PcFe]Cl as a catalyst for the synthesis of new class of ethyl glycinate amino acid derivatives, turnover numbers up to 3360 have been achieved. 36 – 69 % yields were obtained in the case of single N-H insertion products and up to 77 % in the case of double N-H insertion products

Heteroleptic Crown-Substituted Tris(phthalocyaninates) as Dynamic Supramolecular Scaffolds with Switchable Rotational States and Tunable Magnetic Properties

Herein we report single-crystal X-ray diffraction characterization and complementary solution studies of supramolecular interaction between potassium salts and heteroleptic homo- and heteronuclear triple-decker crown phthalocyaninates [(15C5)4Pc]M*[(15C5)4Pc]M(Pc) or [M*,M], where M∗ and M = Y and/or Tb. Our results evidence that, in contrast to the previously studied crown-substituted phthalocyanines, the interaction of K+ cations with [M*,M] does not induce their intermolecular aggregation. Instead, the cations reversibly intercalate between the crown-substituted phthalocyanine ligands, resulting in switching of the coordination polyhedron of the metal center M∗ from square-antiprismatic to square-prismatic. In the case of terbium(III) complexes, such a switching alters their magnetic properties, which can be read-out by 1H NMR spectroscopy. For [Tb*,Y], such a switching causes an almost 25% increase in the axial component of the magnetic susceptibility tensor. Even though the polyhedron of the paramagnetic center in [Y*,Tb] is not switched, minor structural perturbations associated with the overall reorganization of the receptor also cause smaller, but nevertheless appreciable, growth of the axial anisotropy. The observed effects render the studied complexes as molecular switches with tunable magnetic properties.

Functional supramolecular systems: Design and applications

The interest in functional supramolecular systems for the design of innovative materials and technologies, able to fundamentally change the world, is growing at a high pace. The huge array of publications that appeared in recent years in the global literature calls for systematization of the structural trends inherent in the formation of these systems revealed at different molecular platforms and practically useful properties they exhibit. The attention is concentrated on the topics related to functional supramolecular systems that are actively explored in institutes and universities of Russia in the last 10-15 years, such as the chemistry of host-guest complexes, crystal engineering, self-assembly and self-organization in solutions and at interfaces, biomimetics and molecular machines and devices