Exchange interaction between S= 1/2 centers bridged by multiple noncovalent interactions: Contribution of the individual chemical pathways to the magnetic coupling

Polyhedron ◽  
2017 ◽  
Vol 123 ◽  
pp. 404-410 ◽  
Author(s):  
Ana L. Pérez ◽  
Nicolás I. Neuman ◽  
Ricardo Baggio ◽  
Carlos A. Ramos ◽  
Sergio D. Dalosto ◽  
...  
Keyword(s):  
Exchange Interaction ◽  
Noncovalent Interactions ◽  
Magnetic Coupling ◽  
The Individual

Theoretical insights into the origin of magnetic exchange and magnetic anisotropy in {ReIV–MII} (M = Mn, Fe, Co, Ni and Cu) single chain magnets

2016 ◽  
Vol 45 (19) ◽  
pp. 8201-8214 ◽  
Author(s):  
Saurabh Kumar Singh ◽  
Kuduva R. Vignesh ◽  
Velloth Archana ◽  
Gopalan Rajaraman
Keyword(s):  
Magnetic Anisotropy ◽  
Exchange Interaction ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Magnetic Coupling ◽  
Single Chain ◽  
Magnetic Exchange Interaction ◽  
Magnetic Exchange ◽  
Single Chain Magnets

Density functional calculations have been performed on a series of {ReIV–MII} (M = Mn(1), Fe(2), Co(3), Ni(4), Cu(5)) complexes to compute the magnetic exchange interaction between the ReIV and MII ions, and understand the mechanism of magnetic coupling in this series.

scholarly journals Combined Molecular Dynamics and DFT Simulation Study of the Molecular and Polymer Properties of a Catechol-Based Cyclic Oligomer of Polyether Ether Ketone

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1054
Author(s):  
Pradeep R. Varadwaj
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Noncovalent Interactions ◽  
Supramolecular Assembly ◽  
Binary Complex ◽  
Cyclic Oligomer ◽  
Polyether Ether Ketone ◽  
Wide Range ◽  
Ether Ketone ◽  
The Individual

The geometrical, energetic, noncovalent, and material properties of a catechol-based cyclic oligomer of Polyether Ether Ketone (PEEK) called o-PEEK were investigated using Molecular Dynamics (MD) and Density Functional Theory (DFT) simulations. The DFT (and MD) calculation performed with the PBEsol functional (and COMPASS II force field) gave a density of 1.39 (and 1.36) gcm−3 and a volume of 2744.5 (and 2808.5) cm3 for o-PEEK and are comparable with the corresponding experimental values of 1.328 gcm−3 and 2884.6 cm3, respectively. The absolute values of the glass transition temperature (Tg) MD simulated using the unit-cell and 2 × 2 × 2 supercell geometries of the o-PEEK system were 424.4 and 428.6 K, respectively. Although these values slightly differ from each other, both are close to the experiment (Tg = 418.2 K). The results of the (charge) density gradient analysis suggest that the supramolecular assembly between the o-PEEK oligomers in the experimentally observed infinite semi-crystal is driven by a wide range of noncovalent interactions. While the individual local interactions between the oligomers were recognized to be weak-to-medium in strength and are theoretically difficult to quantify, the B97-D3/cc-pVTZ level stabilization energy responsible for the formation of each of the five binary complex configurations extracted from the PBEsol relaxed 2 × 2 × 2 supercell geometry of the o-PEEK system was calculated to vary between –3.5 and –33.0 kcal mol−1.

A New Emphasis in Strategies for Developing Lignin-Based Plastics

1990 ◽  
Vol 197 ◽  
Author(s):  
Sunil Dutta ◽  
Simo Sarkanen
Keyword(s):  
Noncovalent Interactions ◽  
Chemical Species ◽  
Polymeric Materials ◽  
The United States ◽  
Kraft Lignin ◽  
Size Exclusion ◽  
University Of Minnesota ◽  
The Individual ◽  
The University ◽  
Molecular Components

ABSTRACTLignins, a truly abundant group of biopolymers exhibiting some significant diversity, are usually thought to be constituted by a random proportionate distribution of ten different linkages between p-hydroxphenylpropane units. Over 20 million tons of kraft lignin derivatives are produced annually in the United States by the pulping industry, but 99.9% of these aromatic polymeric materials are consumed as fuel. Such industrial byproducts are generally viewed as being almost hopelessly complicated mixtures of partially degraded and condensed chemical species. However, a very different picture has begun to emerge from a more coherent understanding of the physicochemical behavior exhibited by kraft lignin preparations. Noncovalent interactions between the individual molecular components under a variety of solution conditions orchestrate pronounced associative processes that are characterized by a remarkable degree of specificity. Their consequences may be readily observed both size-exclusion chromatographically and electron microscopically, and are reflected in an anomalous variation of glass transition temperature, Tg, with molecular weight of paucidisperse kraft lignin fractions. How these effects may influence the mechanical properties of lignin-based polymeric materials is presently being scrutinized at the University of Minnesota.

scholarly journals Crystallographic and computational study of a network composed of [ZnCl4]2− anions and triply protonated 4′-functionalized terpyridine cations

2017 ◽  
Vol 73 (12) ◽  
pp. 1121-1130 ◽  
Author(s):  
Juan Granifo ◽  
Sebastián Suárez ◽  
Fernando Boubeta ◽  
Ricardo Baggio
Keyword(s):  
Computational Study ◽  
Noncovalent Interactions ◽  
Global Analysis ◽  
Crystallographic Analysis ◽  
Enrichment Ratio ◽  
Acta Cryst ◽  
Packing Arrangement ◽  
Point To Point ◽  
The Individual ◽  
Protonated Cation

We report herein the synthesis, crystallographic analysis and a study of the noncovalent interactions observed in the new 4′-substituted terpyridine-based derivative bis[4′-(isoquinolin-2-ium-4-yl)-2,2′:6′,2′′-terpyridine-1,1′′-diium] tris[tetrachloridozincate(II)] monohydrate, (C24H19N4)2[ZnCl4]3·H2O or (ITPH3)2[ZnCl4]3·H2O, where (ITPH3)3+ is the triply protonated cation derived from 4′-(isoquinolin-4-yl)-2,2′:6′,2′′-terpyridine (ITP) [Granifo et al. (2016). Acta Cryst. C72, 932–938]. The (ITPH3)3+ cation presents a number of interesting similarities and differences compared with its neutral ITP relative, mainly in the role fulfilled in the packing arrangement by the profuse set of D—H...A [D (donor) = C, N or O; A (acceptor) = O or Cl], π–π and anion...π noncovalent interactions present. We discuss these interactions in two different complementary ways, viz. using a point-to-point approach in the light of Bader's theory of Atoms In Molecules (AIM), analyzing the individual significance of each interaction, and in a more `global' analysis, making use of the Hirshfeld surfaces and the associated enrichment ratio (ER) approach, evaluating the surprisingly large co-operative effect of the superabundant weaker contacts.

Supramolecular Materials

MRS Bulletin ◽  
2000 ◽  
Vol 25 (4) ◽  
pp. 26-29 ◽  
Author(s):  
Jeffrey S. Moore
Keyword(s):  
Structural Control ◽  
Noncovalent Interactions ◽  
Molecular Engineering ◽  
Supramolecular Materials ◽  
The Subject ◽  
The Individual

This issue of MRS Bulletin is devoted to the subject of supramolecular materials. The term supramolecular is widely used to describe the intentional use of noncovalent interactions to bring about a desired arrangement of molecules. As the articles in this issue illustrate, this type of molecular engineering can provide structural control on the nanoscale and beyond, broadly impacting the properties of the resulting materials. The goal is to create a collection of molecules in which the whole possesses characteristics that are different and unattainable from the individual components.

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