Stable crystalline lattices in two-dimensional binary mixtures of dipolar particles

The phase diagram of binary mixtures of particles interacting via a pair potential of parallel dipoles is computed at zero temperature as a function of composition and the ratio of their magnetic susceptibilities. Using lattice sums, a rich variety of different stable crystalline structures is identified including $A_mB_n$ structures. [$A$ $(B)$ particles correspond to large (small) dipolar moments.] Their elementary cells consist of triangular, square, rectangular or rhombic lattices of the $A$ particles with a basis comprising various structures of $A$ and $B$ particles. For small (dipolar) asymmetry there are intermediate $AB_2$ and $A_2B$ crystals besides the pure $A$ and $B$ triangular crystals. These structures are detectable in experiments on granular and colloidal matter.Comment: 6 pages - 2 figs - phase diagram update

Crystal nuclei and structural correlations in two-dimensional colloidal mixtures: experiment versus simulation

We examine binary mixtures of superparamagnetic colloidal particles confined to a two-dimensional water-air interface both by real-space experiments and Monte-Carlo computer simulations at high coupling strength. In the simulations, the interaction is modelled as a pairwise dipole-dipole repulsion. While the ratio of magnetic dipole moments is fixed, the interaction strength governed by the external magnetic field and the relative composition is varied. Excellent agreement between simulation and experiment is found for the partial pair distribution functions including the fine structure of the neighbour shells at high coupling. Furthermore local crystal nuclei in the melt are identified by bond-orientational order parameters and their contribution to the pair structure is discussed

Structural investigation of a new cadmium coordination compound prepared by sonochemical process: Crystal structure, Hirshfeld surface, thermal, TD-DFT and NBO analyses

The final publication is available at Elsevier via https://doi.org/10.1016/j.ultsonch.2018.11.024. © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/A new nanostructured cadmium complex containing a tridentate Schiff base ligand was sonochemically synthesized and characterized by XRPD, FT/IR, NMR, and single crystal X-ray crystallography. Structural data showed that cadmium(II) ion is surrounded by three nitrogen atoms of Schiff base ligand and two iodide anions. The crystal packing was contained the intermolecular interactions such as CH⋯O, CH⋯I and π⋯π interactions organizing the self-assembly process. Hirshfeld surfaces and corresponding fingerprint plots have been used for investigation of the nature and proportion of interactions in the crystal packing. FT/IR, NMR and XRD data were in agreement with the X-ray structure and confirm the phase purity of the prepared sample. The molecular structure of the complex was optimized by density functional theory (DFT) calculation at the B3LYP/LANL2DZ level of theory and the results were compared with experimental ones. For more concise study of structure and spectral aspects of the complex, natural bond orbital (NBO) analysis and time-dependent density functional theory (TD-DFT) have been also performed. Thermal stability of the cadmium iodide complex was investigated by thermogravimetric analysis (TGA). Finally, cadmium oxide nanoparticles was prepared by direct calcination of CdLI2 complex as a new precursor.Partial support of this work by Yasouj University is appreciated

Dynamical correlations and collective excitations of Yukawa liquids

In dusty (complex) plasmas, containing mesoscopic charged grains, the grain-grain interaction in many cases can be well described through a Yukawa potential. In this Review we summarize the basics of the computational and theoretical approaches capable of describing many-particle Yukawa systems in the liquid and solid phases and discuss the properties of the dynamical density and current correlation spectra of three- and two-dimensional strongly coupled Yukawa systems, generated by molecular dynamics simulations. We show details of the $\omega(k)$ dispersion relations for the collective excitations in these systems, as obtained theoretically following the quasilocalized charge approximation, as well as from the fluctuation spectra created by simulations. The theoretical and simulation results are also compared with those obtained in complex plasma experiments.Comment: 54 pages, 31 figure

Ionic mixtures in two dimensions: From regular to empty crystals

The ground state of a two-dimensional ionic mixture at zero pressure composed of oppositely charged spheres is determined as a function of the size asymmetry by using a penalty method. The cascade of stable structures includes square, triangular and rhombic crystals as well as “empty” crystals made up of dipoles and chains, which have a vanishing number density. Thereby we confirm the square structure, found experimentally on charged granulates, and predict new phases detectable in experiments on granular and colloidal matter

Not Too Big and Not Too Small: “Goldilocks” Anion Size for Three-Dimensional Metal–Organic Frameworks Containing Oligothiophene Dinitrile Ligands (C₄H₂S)_<i>n</i>(CN)₂ (<i>n</i> = 1, 2, 3) Bridging Silver(I) Cations

A series of oligothiophene dinitriles, containing one, two, or three oligothiophene rings between nitrile donors NC-(C₄H₂S)_<i>n</i>-CN are reacted with silver­(I) salts to form coordination compounds. In most cases, the resulting metal–organic frameworks are one-dimensional coordination polymers containing roughly linear divalent Ag­(I) centers. However, in the case of bithiophene (<i>n</i> = 2) and terthiophene (<i>n</i> = 3) bridges, a three-dimensional structure is also possible if the silver­(I) counterion is just the right size to fit into the diamondoid pores that form with four-coordinate tetrahedrally oriented Ag­(I) centers. Thus, only ClO₄^– and BF₄^– form three-dimensional structures with the bithiophene-bridged ligands, while the larger CF₃SO₃^– and SbF₆^– anions will support a three-dimensional structure for the terthiophene-bridged ligand. Any counterion larger or smaller than the “just right” size will result in the one-dimensional structure instead