Revisiting the Assignment of Innocent and Non-Innocent Counter ions in Lanthanide(III) Solution Chemistry

Lanthanides are found in critical applications from display technology to renewable energy. Often these rare earth elements are used as alloys or functional materials, yet the access to them are trough solution processes. In aqueous solution the rare earths are found predominantly as trivalent ions and charge balance dictates that counter ions are present. The fast ligand exchange and lack of directional bonding in lanthanides complexes has led to questions regarding the speciation of Ln3+ solvates in the presence of various counter ions, and to the distinction between innocent = non-coordinating, and non-innocent = coordinating counter ions. There is limited agreement as to which counter ions that belong to each group, which lead to this report. By using Eu3+ luminescence, it was possible to clearly distinguish between coordinating and non-coordinating ions. To interpret the results it was required to bridge the descriptions of ion pairing and coordination. The da-ta—in form of Eu3+ luminescence spectra and luminescence lifetimes from solutions with varying concentrations of acetate, chloride, nitrate, fluoride, sulfate, perchlorate and triflate—were contrasted to those obtained with ethylenediaminetet-raaceticacid (EDTA), which allowed for the distinction between three Ln3+-anion interaction types. It was possible to con-clude which counter ions are truly innocent (e.g. ClO4- and OTf-), and which clearly coordinate (e.g. NO3- and AcO-). Finally, the considerate amount of data from systems studied under similar conditions allowed the minimum perturbation arising from inner sphere or outer sphere coordination in Eu3+ complexes to be identified.

Patchy Nanoparticle Synthesis and Self-Assembly

Biological building blocks (i.e., proteins) are encoded with the information of target structure into the chemical and morphological patches, guiding their assembly into the levels of functional structures that are crucial for living organisms. Learning from nature, researchers have been attracted to the artificial analogues, “patchy particles,” which have controlled geometries of patches that serve as directional bonding sites. However, unlike the abundant studies of micron-scale patchy particles, which demonstrated complex assembly structures and unique behaviors attributed to the patches, research on patchy nanoparticles (NPs) has remained challenging. In the present chapter, we discuss the recent understandings on patchy NP design and synthesis strategies, and physical principles of their assembly behaviors, which are the main factors to program patchy NP self-assembly into target structures that cannot be achieved by conventional non-patched NPs. We further summarize the self-assembly of patchy NPs under external fields, in simulation, and in kinetically controlled assembly pathways, to show the structural richness patchy NPs bring. The patchy NP assembly is novel by their structures as well as the multicomponent features, and thus exhibits unique optical, chemical, and mechanical properties, potentially aiding applications in catalysts, photonic crystals, and metamaterials as well as fundamental nanoscience.

Ordered colloidal clusters constructed by nanocrystals with valence for efficient CO2 photoreduction

The ability to construct discrete colloidal clusters (CCs) as complex as molecular clusters is limited due to the lack of available colloidal building blocks and specific directional bonds. Here, we explore a strategy to organize anisotropic Prussian blue analog nanocrystals (NCs) toward CCs with open and highly ordered structures, experimentally realizing colloidal analogs to zeolitic clathrate structures. The directional interactions are derived from either crystallographic or morphological anisotropy of the NCs and achieved by the interplay of epitaxial growth, oriented attachment, and local packing. We attribute these interparticle interactions to enthalpic and entropic valences that imitate hybridized atomic orbitals of sp3d2 octahedron and sp3d3f cube. Benefiting from the ordered multilevel porous structures, the obtained CCs exhibit greatly enhanced catalytic activity for CO2 photoreduction. Our work offers some fundamental insights into directional bonding among NCs and opens an avenue that promises access to unique CCs with unprecedented structures and applications.

Effect of Cr on electronic and mechanical properties of TiS2 compound: A first-principles study

The electronic structural and mechanical properties for hexagonal structure of unpolarized TiS2Cr and spin-polarized TiS2Cr compounds have been studied using first principles pseudo potential plane wave method. The equilibrium lattice constant values of unpolarized TiS2 and TiS2Cr compounds are in agreement with the available theoretical data. The unpolarized TiS2 and TiS2Cr compounds display metallic bonding whereas spin-polarized TiS2Cr shows directional bonding. Based on shear to bulk modulus (G/B) ratios, the unpolarized TiS2 and TiS2Cr compounds are associated with ductile behaviour whereas spin-polarized TiS2Cr compound shows brittle nature. The Debye temperature ( ) is higher for spin-polarized TiS2Cr.