0000000000328333
AUTHOR
Wladimiro Díaz
ortho-metallation of P(m-MeC6H4)3 in dirhodium(II) tetraacetate. Molecular structure of Rh2(O2CCH3)2[(m-MeC6H3)P(m-MeC6H4)2]2(HO2CCH3)2·CH3CO2H
Abstract The thermal reaction of Rh2(O2CCH3)4(MeOH)2 and P(m-MeC6H4)3 in a 1:2 molar ratio in acetic acid yielded Rh2(O2CCH3)2[(m-MeC6H3)P(m -MeC6H4)2]2(HO2CCH3)2. Purple monoclinic crystals of this compound and one molecule of acetic acid, space group P21/c, were obtained by evaporation of a solution of the original reaction product in acetic acid/CH2Cl2 mixture. The unit cell parameters are a = 21.346(3), b = 11.909(2), c = 20.071 A, β = 97.98(1)° and Z = 4. The structure consists of a dinuclear rhodium core bridged by cisoid acetate groups and two ortho-metallated phosphine ligands. The ortho-metallation occurs at the least sterically hindered carbon atom which is trans to the methyl sub…
Exploring the diversity of the human blood virome
This article belongs to the Special Issue Virus Bioinformatics 2022.
Prediction and Discrimination of Pharmacological Activity by Using Artificial Neural Networks
The design of new medical drugs is a very complex process in which combinatorial chemistry techniques are used. For this reason, it is very useful to have tools to predict and to discriminate the pharmacological activity of a given molecular compound so that the laboratory experiments can be directed to those molecule groups in which there is a high probability of finding new compounds with the desired properties. This work presents an application of Artificial Neural Networks to the problem of discriminating and predicting pharmacological characteristics of a molecular compound from its topological properties. A large amount of different configurations are tested, yielding very good perfor…
Improving Pattern Recognition Based Pharmacological Drug Selection Through ROC Analysis
The design of new medical drugs is a very complex process in which combinatorial chemistry techniques are used. The goal consists of discriminating between molecular compounds exhibiting or not certain pharmacological activities. Different machine learning approaches have been recently applied to different drug design problems leading to competitive results in pointing at particular compounds with high probability of exhibiting activity. The present work first deeps into the natural trade-off between accuracy in the much less populated active group and false alarm rate which could lead to too many expensive laboratory tests. Preliminary results show how different classification techniques a…
Solution chemistry of N,N'-ethylenebis(salicylideneimine) and its copper(II), nickel(II) and iron(III) complexes
Abstract Potentiometric determination of protonation-deprotonation equilibria of the N,N'-ethylenebis(salicylideneimine) (H2sal2en), the related N-(2-aminoethyl)salicylideneimine, (Hsalen), and their organic fragments, salicylaldehyde (Hsal) and ethylenediamine (en), has been used to study the equilibria involved in the formation of Schiff bases from Hsal, sal− and en and in their complex formation with copper(II), nickel(II) and iron(III) ions in dimethyl sulfoxide (dmso)-water (80:20 wt./wt.) mixture (25 °C and 0.1 mol dm−3 KClO4 ionic strength): en+Hsal⇔Hsalen; en+2Hsal⇔H2sal2en; en+ sal−⇔salen−; en+2sal−⇔sal2en2−; sal−+en+MN+⇔[M(salen)](n−1)+; 2sal−+en+Mn+⇔ [M(sal2en)](n−2)+. In these t…
Soil Bacterial Community Along an Altitudinal Gradient in the Sumaco, a Stratovolcano in the Amazon Region
Our study is a pioneering exploration of the microbiome in the soil of the Sumaco stratovolcano and an assessment of the effects of an elevational gradient and related physicochemical soil parameters on richness and community structure. The Sumaco, as an isolated Amazonian stratovolcano, may be among one of the least studied ecosystems in Ecuador and perhaps the Amazon region. Universal patterns remain unresolved or available information inconclusive to establish a supported consensus on general governing processes by which elevation and its associated environmental gradients may determine the microbial richness and community structure. We tested a recent proposal on how microbial diversity…
Study of the interaction between [Cu(bipy)]2+ and oxalate in dimethyl sulfoxide. Crystal structure of [Cu2(bipy)2(H2O)2ox]SO4·[Cu(bipy)ox]
Abstract A study of complex formation between [Cu(bipy)]2+ and ox2− (bipy and ox2− being 2,2′-bipyridyl and the dianion of oxalic acid), has been carried out by potentiometry in dimethyl sulfoxide solution. The constants of the equilibria and are log β110 = 11.165(1) and log β210 = 13.185(5) at 25 °C and 0.1 mol dm−3 tetra-n- butylammonium perchlorate. The high values of these constants are consistent with the symmetrical bidentate and bis-bidentate modes of oxalate in [Cu(bipy)ox] and [Cu2(bipy)2ox]2+ units, respectively, as shown by X-ray diffraction studies. Well-formed single crystals of [Cu2(bipy)2(H2O)2ox]SO4· [Cu(bipy)ox] were grown from aqueous solutions and characterized by X-ray d…
Use of parallel computing to improve the accuracy of calculated molecular properties
Calculation of electron correlation energy in molecules is unavoidable in accurate studies of chemical reactivity. However, these calculations involve, a computational effort several, even in the simplest cases, orders of magnitude larger than the computer power nowadays available. In this work the possibility of parallelize the calculations of the electron correlation energy is studied. The formalism chosen is the dressing of matrices in both distributed and shared memory parallel systems MIMD. Algorithms developed on PVM are presented, and the results are evaluated on several platforms. These results show that the parallel techniques are useful in order to decrease very appreciably the ti…