Coordination Chemistry in Europe since Alfred Werner

The development of coordination chemistry in Europe since Alfred Werner's epoch-making 1893 publication is reviewed. Mention will be made of the work done by the German School (P. Pfeiffer, F. Hein, W. Hieber, W. Reppe, W. Klemm, E.O. Fischer), the French School (M. Délépine, R. Charronat, A. Joly, J.-P. Mathieu), the Scandinavian School (K.A. Jensen, J. Bjerrum, I. Leden, L.G. Sillen), the English School (F.G. Mann, J. Chatt, R.S. Nyholm, G. Wilkinson), the Russian School (L.A. Chugaev, I.I. Chernyaev, A.A. Grinberg, K.J. Jatzimirski), the Italian School (A. Miolati, L. Cambi, L. Malatesta, P. Chini), and the Swiss School (G. Schwarzenbach)

Peptide self‐assembled nanostructures: from models to therapeutic peptides

: Self-assembly is the most suitable approach to obtaining peptide-based materials on the nano- and mesoscopic scales. Applications span from peptide drugs for personalized therapy to light harvesting and electron conductive media for solar energy production and bioelectronics, respectively. In this study, we will discuss the self-assembly of selected model and bioactive peptides, in particular reviewing our recent work on the formation of peptide architectures of nano- and mesoscopic size in solution and on solid substrates. The hierarchical and cooperative characters of peptide self-assembly will be highlighted, focusing on the structural and dynamical properties of the peptide building blocks and on the nature of the intermolecular interactions driving the aggregation phenomena in a given environment. These results will pave the way for the understanding of the still-debated mechanism of action of an antimicrobial peptide (trichogin GA IV) and the pharmacokinetic properties of a peptide drug (semaglutide) currently in use for the therapy of type-II diabetes

Nucleic acids in mummified plant seeds : biochemistry and molecular genetics,of pre-Columbian maize

SummaryNucleic acids fractions were isolated from pre-Columbian maize seeds and characterized using different approaches such as polyacrylamide gel electrophoresis, anti-DNA antibody binding, HPLC fractionation, molecular hybridization with cloned genes, and DNA amplification by the polymerase chain reaction. The nucleic acids were found to be very depolymerized (≤140 base pairs in length) and composed mainly of ribosomal RNA. Despite the very low amount and degree of polymerization of seed DNA, specific maize nuclear Mul, Mu4, Mu8 and, possibly, Mu5 element components could be detected, thanks to the use of amplification systems as short as 90 bp. The results suggest that evaluation of the relative proportions of Mu-type element components and, possibly, other maize genomic components in single mummified kernels, may offer a new key to the study of ancient maize populations

Towards the “Eldorado” of pKa Determination: A Reliable and Rapid DFT Model

The selection of a “perfect tool” for the theoretical determination of acid-base dissociation constants (Ka) is still puzzling. Recently, we developed a user-friendly model exploiting CAM-B3LYP for determining pKa with impressive reliability. Herein, a new challenge is faced, examining a panel of functionals belonging to different rungs of the “Jacob’s ladder” organization, which classifies functionals according to their level of theory. Specifically, meta-generalized gradient approximations (GGAs), hybrid-GGAs, and the more complex range-separated hybrid (RSH)-GGAs were investigated in predicting the pKa of differently substituted carboxylic acids. Therefore, CAM-B3LYP, WB97XD, B3PW91, PBE1PBE, PBEPBE and TPSSTPSS were used, with 6-311G+(d,p) as the basis set and the solvation model based on density (SMD). CAM-B3LYP showed the lowest mean absolute error value (MAE = 0.23) with relatively high processing time. PBE1PBE and B3PW91 provided satisfactory predictions (MAE = 0.34 and 0.38, respectively) with moderate computational time cost, while PBEPBE, TPSSTPSS and WB97XD led to unreliable results (MAE > 1). These findings validate the reliability of our model in predicting carboxylic acids pKa, with MAE well below 0.5 units, using a simplistic theoretical level and a low-cost computational approach

The self-aggregation of porphyrins with multiple chiral centers in organic/aqueous media: the case of sugar: the steroid-porphyrin conjugates

An overview of the solvent-driven aggregation of a series of chiral porphyrin derivatives studied by optical methods (uv/vis, fluorescence, cd and rls spectroscopies) is herein reported; the investigated porphyrins are characterized by the presence in the meso-positions of glycol-, steroidal- and glucosteroidal moieties, conferring amphiphilicity and solubility in aqueous media to the primarily hydrophobic porphyrin platform. Aggregation of the macrocycles is driven by a change in bulk solvent composition, forming architectures with supramolecular chirality, steered by the stereogenic centers on the porphyrin peripheral positions. The aggregation behavior and chiroptical properties of the final aggregated species strongly depend on the number and stereogenicity of the ancillary groups that dictate the mutual spatial arrangement of the porphyrin chromophores and their further organization in larger structures, usually detectable by different microscopies, such as AFM and SEM. Kinetic studies are fundamental to understand the aggregation mechanism, which is frequently found to be dependent on the substrate concentration. Additionally, Molecular Mechanics calculations can give insights into the intimate nature of the driving forces governing the self-assembly process. The critical use of these combined methods can shed light on the overall self-assembly process of chirally-functionalized macrocycles, with important implications on the development of chiral porphyrin-based materials

Modelo de Ingreso de Datos a la Herramienta de Costos del Sistema de Transporte Público de Pasajeros

Las pequeñas y medianas ciudades se enfrentan a una serie de dificultades a la hora de administrar y manejar su sistema de transporte urbano. Esta problemática se debe a que no cuentan con los métodos necesarios para analizar y administrar los recursos que poseen. Surgida esta necesidad, el propósito de este estudio es recabar los datos necesarios para operar una herramienta de costos del sistema de transporte público que se pueda emplear para el cálculo de costos en ciudades con características similares. El mecanismo de implementación consiste en la interacción de los usuarios a través de preguntas que permitan segmentar el servicio que brindan en un escenario en particular y, por medio de esta categorización, poder brindar los parámetros e información pertinente al entorno que se encuentran. Como resultado final del proceso, a través de fórmulas matemáticas de costos, el sistema entregará como salida, el valor buscado del costo

Tetraferrocenylporphyrins as active components of self-assembled monolayers on gold surface.

Novel tetraferrocenylporphyrins-containing self-assembled monolayers were prepared employing two different approaches. Self-assembled monolayers were characterized using UV-Vis spectroscopy and cyclic voltammetry (CV) whereas their photoelectrochemical properties were investigated by photocurrent generation (PG) experiments