Importance of electron correlation effects and basis set superposition error in calculations of interaction energies and interaction-induced electric properties in hydrogen-bonded complexes: a model study

A detailed study of the interaction energies and interaction-induced electric dipole properties in model linear hydrogen cyanide complexes (HCN) m (m = 2–4) is carried out within the finite field HF SCF, MP2, CCSD and CCSD(T) approximations using the recently developed LPol-n (n = ds, fs, dl, fl) basis sets. The importance of high-order correlation effects and the basis set superposition error is evaluated. To correct for the latter is crucial for obtaining accurate interaction energy values, but the error can safely be neglected in the estimation of induced electric properties when the LPol-n (n = ds, fs, dl, fl) basis sets are used. Correlation effects are important in the evaluation of both the interaction energies and the induced electric properties of the systemsThis work was supported by the Spanish Ministerio de Ciencia e Innovación (CTQ2008-01861/BQU project), the Xunta de Galicia and FEDER (Axuda para Consolidación e Estructuración de Unidades de Investigación Competitivas do Sistema Universitario de Galicia 2007/050, and 2007-2013 and INCITE09 314 252 PR projects), and by the Foundation for Polish Science within the Homing Plus programme (Homing Plus/2010-1/2), cofinanced from European Regional Development Fund within Innovative Economy Operational ProgrammeS

From Oligo(Phenyleneethynylene) Monomers to Supramolecular Helices: The Role of Intermolecular Interactions in Aggregation

Supramolecular helices that arise from the self-assembly of small organic molecules via non-covalent interactions play an important role in the structure and properties of the corresponding materials. Here we study the supramolecular helical aggregation of oligo(phenyleneethynylene) monomers from a theoretical point of view, always guiding the studies with experimentally available data. In this way, by systematically increasing the number of monomer units, optimized n-mer geometries are obtained along with the corresponding absorption and circular dichroism spectra. For the geometry optimizations we use density functional theory together with the B3LYP-D3 functional and the 6–31G** basis set. For obtaining the spectra we resort to time-dependent density functional theory using the CAM-B3LYP functional and the 3–21G basis set. These combinations of density functional and basis set were selected after systematic convergence studies. The theoretical results are analyzed and compared to the experimentally available spectra, observing a good agreementThis research was funded by Ministerio de Ciencia e Innovación, grant number PID2019-107307RB-100; Xunta de Galicia, grants number and ED431C 2018/30, ED431C 2017/17 and ED431G 2019/03; and the European Regional Development Fund (ERDF)S

Dissymmetric Chiral Poly(diphenylacetylene)s: Secondary Structure Eluci

The 3D helix adopted by a non-symmetric substituted poly(diphenylacetylene) (PDPA) is elucidated, and its ability to self-assemble into nanospheres or fiber-like structures under the right conditions is also demonstrated. Moreover, by conformational changes in the pendant group it is possible to produce a helix inversion in the PDPA and create a circular polarized luminescence (CPL) switch. The secondary structure of a dissymmetric and chiral poly(diphenylacetylene) (PDPA) is elucidated by combining the data from NMR experiments (regioregular head to tail structure), Raman and IR studies (E configuration of the polyene double bonds), and high-resolution AFM images (helical pitch, packing angle and orientation of the external helix). As a result, an E-transoidal polyene backbone describing three coaxial helices is obtained. Theoretical electronic circular dichroism (ECD) studies of the structure show a good correspondence between experimental and theoretical data and allow one to decipher that the first Cotton band is generated by the poly(diphenylacetylene) core and not only by the polyene backbone. The dynamic behavior of poly-(S)-2 is also demonstrated by a helix inversion effect produced by conformational changes at the pendant groups when annealed in solvents with different donor abilities. This phenomenon is accompanied by an inversion of the circular polarized luminescence of the PDPA (CPL switch)Agencia Estatal de Investigación. Grant Numbers: PID2019-109733GB-I00, PID2019-107307RB-100, PID2020-117605GB-100. Secretaria Xeral de Investigación e Desenvolvemento, Xunta de Galicia. Grant Numbers: ED431C 2018/30, ED431C 2021/40, ED431G 2019/03S

Ejercicio físico basado en descansos activos sobre la función cognitiva y la competencia matemática en estudiantes universitarios de grado

A review of the literature has demonstrated the impact of active breaks (AB) on students’ cognition and academic performance. Despite the evidence, undergraduate students seem to remain passive during the lessons as the teaching is mostly traditional and revolves around the teacher. To break with this tendency in the university context, we included physical activity (PA) breaks during lessons. This study aimed to observe the acute effect of AB on the students’ attention and mathematical competence. A total of 25 undergraduate students (Mage = 23.36, SD = 1.98) participated in this study and performed an intervention under two conditions: i) control condition and ii) active-break condition. Results revealed that after receiving an AB (15 minutes) of moderate intensity students’ attention was improved. More specifically, participants were faster at D2 and their math tasks results improved.La literatura ha demostrado el impacto de los descansos activos (AB; active breaks en inglés) en la cognición y el rendimiento académico de los estudiantes. A pesar de la evidencia, los estudiantes universitarios parecen permanecer pasivos durante las lecciones, ya que la enseñanza es mayoritariamente tradicional y gira en torno al profesor. Para romper con esta tendencia en el contexto universitario, incluimos pausas de actividad física (AF) durante las clases. Este estudio de casos cruzados tiene como objetivo observar el efecto agudo de los descansos activos en la atención y la competencia matemática de los estudiantes. Un total de 25 estudiantes de grado (Medad = 23,36, DE = 1,98) participaron en este estudio y realizaron una intervención bajo dos condiciones: i) condición de control y ii) condición de descansos activos. Los resultados muestran que los estudiantes mejoraron su atención después de recibir una sesión de descanso activo (15 minutos) de intensidad moderada. En este sentido, los participantes fueron más rápidos en D2 y mejoraron sus resultados en la tarea de matemáticas

Influence of Multiple Conformations and Paths on Rate Constants and Product Branching Ratios. Thermal Decomposition of 1-Propanol Radicals

The potential energy surface involved in the thermal decomposition of 1-propanol radicals was investigated in detail using automated codes (tsscds2018 and Q2DTor). From the predicted elementary reactions, a relevant reaction network was constructed to study the decomposition at temperatures in the range 1000–2000 K. Specifically, this relevant network comprises 18 conformational reaction channels (CRCs), which in general exhibit a large wealth of conformers of reactants and transition states. Rate constants for all the CRCs were calculated using two approaches within the formulation of variational transition-state theory (VTST), as incorporated in the TheRa program. The simplest, one-well (1W) approach considers only the most stable conformer of the reactant and that of the transition state. In the second, more accurate approach, contributions from all the reactant and transition-state conformers are taken into account using the multipath (MP) formulation of VTST. In addition, kinetic Monte Carlo (KMC) simulations were performed to compute product branching ratios. The results show significant differences between the values of the rate constants calculated with the two VTST approaches. In addition, the KMC simulations carried out with the two sets of rate constants indicate that, depending on the radical considered as reactant, the 1W and the MP approaches may display different qualitative pictures of the whole decomposition processThis work was partially supported by the Consellería de Cultura, Educación e Ordenación Universitaria e da Consellería de Economía, Emprego e Industria (Axuda para Consolidación e Estructuración de unidades de investigación competitivas do Sistema Universitario de Galicia, Xunta de Galicia ED431C 2017/17 & Centro singular de investigación de Galicia acreditación 2016-2019, ED431G/09), the Ministerio de Economía y Competitividad of Spain (Research Grant No CTQ2014-58617-R), and the European Regional Development Fund (ERDF). D.F.-C. also thanks Xunta de Galicia for financial support through a postdoctoral grant. The authors thank “Centro de Supercomputación de Galicia (CESGA)” for the use of their computational facilitiesS

Predicting the Helical Sense of Poly(phenylacetylene)s from their Electron Circular Dichroism Spectra

This is the peer reviewed version of the following article: B. Fernández, R. Rodríguez, A. Rizzo, E. Quiñoá, R. Riguera, F. Freire, Angew. Chem. Int. Ed. 2018, 57, 3666, which has been published in final form at https://doi.org/10.1002/anie.201713164. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.The calculated ECD spectrum (time‐dependent density functional theory TD‐DFT) for small oligomers of polyphenylacetylenes (PPAs) show a very good match with the experimental spectra of the PPA polymers, particularly with the first Cotton band associated to the helical sense of the internal polyenic backbone. This has been proven with a series of PPAs representative of cis‐cisoidal, cis‐transoidal, compressed and stretched polyene backbones, with identical or opposite internal/external rotational senses and allows the prediction of the helical sense of the internal helix of a PPA directly from its CD spectraWe also thank the MEIyC [CTQ2014- 61470-EXP, CTQ2015-70519-P, FPI (R. Rodríguez)], XUGA (GRC2014/040, Centro singular de investigación de Galicia acreditation 2016-2019, GRC2014/040, and Axuda para Consolidación e Estruturación de Unidades de Investigación Competitivas do SUG, ED431C 2017/17) and the European Union (ERDF) for financial supportS

Adipose tissue-derived mesenchymal stem cells as a strategy to improve recovery after stroke

Introduction: Based on the positive results observed in experimental animal models, adipose tissue-derived mesenchymal stem cells (AD-MSCs) constitute a promising therapy for stroke treatment. However, several aspects need to be clarified to identify the optimal conditions for successful clinical translation. Areas covered: This review focuses on AD-MSC treatment for ischemic and hemorrhagic stroke in experimental animal models. In addition, we will explore the optimization of treatment conditions including AD-MSC production, administration routes and therapeutic windows for their appropriate use in patients, and we will provide an update on clinical trials on this therapy. Expert opinion: Compared with other cell types, AD-MSCs have been less investigated in stroke studies. Currently, experimental animal models have shown safety and efficacy with this treatment after stroke. Due to several advantages of AD-MSCs, such as their abundance and accessibility, they can be considered a promising strategy for use in patients. However, many questions are still to be resolved regarding their mechanisms of action, immune system modulation and the effects of AD-MSCs on all components of the brain that may be affected after ischemic and hemorrhagic strokesThis project is supported by research grants PS12/01754 (Spanish Ministry of Science) and INVICTUS (RD12/0014/0006) (Spanish Neurovascular Network), and Research Institute Carlos III, Ministry Science and Innovatio

Polymeric Helical Structures à la Carte by Rational Design of Monomers

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Macromolecules, copyright © 2020 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: https://doi.org/10.1021/acs.macromol.0c00085Preparation of helical structures à la carte by monomer design of dynamic helical polymers such as poly(phenylacetylene)s (PPAs) is a difficult task due to conformational freedom of the polyene backbone. Herein, we study the monomer/helical polymer scaffold relationship by preparation of two novel phenylacetylene monomer series substituted at the phenyl ring in ortho-, meta-, or para-positions with the two enantiomers of either α-hydroxy-α-phenylacetic acid (1) or α-chloro-α-phenylacetic acid (S-2) linked through an anilide bond. These monomers were further polymerized, and their secondary structure and dynamic behavior were analyzed. Compiling information from these studies and the structural data for other PPAs found in the literature, we can state that anilide linkages in para-substituted polymers tend to generate compressed cis-cisoidal polyene structures, which can be transformed into more elongated cis-transoidal ones by external stimuli, while benzamide linkages in para-substituted polymers form mainly cis-transoidal scaffolds. The macromolecular structure of PPAs is also largely affected by the aromatic substitution pattern, adopting more stretched scaffolds once the pendant group is placed in meta- or ortho-positions, due to the steric hindrance generated by placing this group closer to the backboneFinancial support from MINECO (CTQ2015-70519-P), Xunta de Galicia (ED431C 2018/30; Centro singular de investigacioń de Galicia accreditation 2016-2019, ED431G/09, R.R. postdoctoral fellowship, and the European Regional Development Fund (ERDF) is gratefully acknowledgedS

Dissociation of a Strong Acid in Neat Solvents: Diffusion Is Observed after Reversible Proton Ejection Inside the Solvent Shell

This is the peer-reviewed version of the following article: The Journal of Physical Chemistry B 2013, 117, 14065–14078, DOI: 10.1021/jp4042765, which has been published in final form at https://pubs.acs.org/doi/abs/10.1021/jp4042765. This article may be used for non-commercial purposes onlyStrong-acid dissociation was studied in alcohols. Optical excitation of the cationic photoacid N-methyl-6-hydroxyquinolinium triggers proton transfer to the solvent, which was probed by spectral reconstruction of picosecond fluorescence traces. The process fulfills the classical Eigen–Weller mechanism in two stages: (a) solvent-controlled reversible dissociation inside the solvent shell and (b) barrierless splitting of the encounter complex. This can be appreciated only when fluorescence band integrals are used to monitor the time evolution of the reactant and product concentrations. Band integrals are insensitive to solvent dynamics and report relative concentrations directly. This was demonstrated by first measuring the fluorescence decay of the conjugate base across the full emission band, independently of the proton-transfer reaction. Multiexponential decay curves at single wavelengths result from a dynamic red shift of fluorescence in the course of solvent relaxation, whereas clean single exponential decays are obtained if the band integral is monitored instead. The extent of the shift is consistent with previously reported femtosecond transient absorption measurements, continuum theory of solvatochromism, and molecular properties derived from quantum chemical calculations. In turn, band integrals show clean biexponential decay of the photoacid and triexponential evolution of the conjugate base in the course of the proton transfer to solvent reaction. The dissociation step follows the slowest stage of solvation, which was measured here independently by picosecond fluorescence spectroscopy in five aliphatic alcohols. Also, the rate constant of the encounter-complex splitting stage is compatible with proton diffusion. Thus, for this photoacid, both stages reach the highest possible rates: solvation and diffusion control. Under these conditions, the concentration of the encounter complex is substantial during the earliest nanosecondWe thank the Spanish Government and the European Regional Development Fund (grant nos. CTQ2010-17835, CTQ2010-17026, and CTQ2011-29311-C02-01) and the Xunta de Galicia (grants nos. CN 2012/314, 2012-PG237, GPC2013/052 and INCITE09 314 252 PR) for financial support of our work. J.L.P.L. thanks the Spanish Ministry of Economy and Competitiveness for funding through the Ramon y Cajal ́ Programm 2009. M.V. and C.C.B. thank the Spanish Government for funding through the FPU program. A. B. thanks the Segundo Gil Dávila Foundation for financial supportS

Effects of intravenous administration of allogenic bone marrow- and adipose tissue-derived mesenchymal stem cells on functional recovery and brain repair markers in experimental ischemic stroke

The electronic version of this article is the complete one and can be found online at: http://stemcellres.com/content/4/1/11Introduction: Stem cell therapy can promote good recovery from stroke. Several studies have demonstrated that mesenchymal stem cells (MSC) are safe and effective. However, more information regarding appropriate cell type is needed from animal model. This study was targeted at analyzing the effects in ischemic stroke of acute intravenous (i.v.) administration of allogenic bone marrow- (BM-MSC) and adipose-derived-stem cells (AD-MSC) on functional evaluation results and brain repair markers. Methods: Allogenic MSC (2 × 106 cells) were administered intravenously 30 minutes after permanent middle cerebral artery occlusion (pMCAO) to rats. Infarct volume and cell migration and implantation were analyzed by magnetic resonance imaging (MRI) and immunohistochemistry. Function was evaluated by the Rogers and rotarod tests, and cell proliferation and cell-death were also determined. Brain repair markers were analyzed by confocal microscopy and confirmed by western blot. Results: Compared to infarct group, function had significantly improved at 24 h and continued at 14 d after i.v. administration of either BM-MSC or AD-MSC. No reduction in infarct volume or any migration/implantation of cells into the damaged brain were observed. Nevertheless, cell death was reduced and cellular proliferation significantly increased in both treatment groups with respect to the infarct group. At 14 d after MSC administration vascular endothelial growth factor (VEGF), synaptophysin (SYP), oligodendrocyte (Olig-2) and neurofilament (NF) levels were significantly increased while those of glial fiibrillary acid protein (GFAP) were decreased. Conclusions: i.v. administration of allogenic MSC - whether BM-MSC or AD-MSC, in pMCAO infarct was associated with good functional recovery, and reductions in cell death as well as increases in cellular proliferation, neurogenesis, oligodendrogenesis, synaptogenesis and angiogenesis markers at 14 days post-infarctThis study was supported by grants from Cellerix, FIS 060575 and PS09/ 01606 (Spanish Ministry of Science), CIDEM (Center for Innovation and Business Development) and by RENEVAS (RD07/0026/2003) (Spanish Neurovascular Network), the Carlos III Research Institute and the Ministry of Science and Innovatio