Entangled Two-Dimensional Coordination Networks: A General Survey

Many of the reported species exhibit the intriguing feature of interpenetration or other types of entanglements. The properties of these materials are related not only to their molecular structures but also to the topology of the individual networks as well as to the way in which the individual nets are entangled. Different synthetic procedures have been developed to attain a certain control of entanglement in coordination networks, and recently some reviews have appeared that are focused on factors governing the entanglements, having in mind their potential applications. However, these analyses are mostly devoted to 3D networks thanks to the great wealth of data on interpenetration. Simplification of a network that contains 2-loops can lead to complete disappearance of the entanglement, and therefore such networks were picked out into a separate group

A topological method for the classification of entanglements in crystal networks

A rigorous method is proposed to describe and classify the topology of entanglements between periodic networks if the links are of the Hopf type. The catenation pattern is unambiguously identified by a net of barycentres of catenating rings with edges corresponding to the Hopf links; this net is called the Hopf ring net. The Hopf ring net approach is compared with other methods of characterizing entanglements; a number of applications of this approach to various kinds of entanglement (interpenetration, polycatenation and self-catenation) both in modelled network arrays and in coordination networks are considered

How 2-periodic coordination networks are interweaved : entanglement isomerism and polymorphism

The entanglements of 1319 2-periodic coordination polymers are examined and fully classified using the extended ring nets (ERNs) approach. The ERNs characterize the entanglement to the greatest detail ever achieved: all possible classes/types/modes of entanglements observed and reported in the literature so far result in 216 ERN topologically distinct modes of entanglements with 74% of all the structures falling into only 21 of them. We also introduce the notion of entanglement isomerism to designate the coordination polymers that have the same chemical composition, local and overall topology, but differ by their catenation patterns as mapped into their ERNs

γ-Brass Polyhedral Core in Intermetallics: The Nanocluster Model

Using the TOPOS program package, 26-atom nanoclusters of the \u3b3-brass (Cu5Zn8) type (0@4@22 or 0@8@18) were found in 5918 crystal structures of cubic intermetallics. The nanocluster models were built for all the intermetallics using a recently developed algorithm implemented into TOPOS. The relations of the structures based on the 0@4@22 core are explored as a result of migration of atoms between different shells of the nanoclusters. It is shown that the 0@4@22 nanoclusters frequently occur as building units of intermetallics of different composition and structure type. Regularities in chemical composition of 702 \u3b3-brass-type nanoclusters were found within both the nanoclusters approach (multishell structure) and the nested-polyhedra model. A database containing all topological types of \u3b3-brass nanoclusters is created with which one can search for the corresponding atomic configuration in any intermetallics

High-throughput ab-initio calculations: materials for energy storage

At present time, sodium-based batteries are considered as the most viable candidates for replacing widespread lithium batteries. Al- and K-based materials (among others) are also envisaged as prospective compounds for the next generation of solid state batteries (SSB). We are calculated the possible migration pathways for a number of Na-, Al-,K- and Li-conductive materials and selected new perspective compounds from ICSD database using ToposPro package, specially designed for study of super-ionic conductors. For the most promising compounds a careful analysis using DFT calculations was performed. The combined study with both topological and DFT approaches is crucial to gain insight into the main features of ionic conductivity

Interpenetration of three-periodic networks in crystal structures : description and classification methods, geometrical-topological conditions of implementation

This review describes the current state of studies on the phenomenon of interpenetration of framework groups in crystal structures. The generally accepted terminology used in the description of topology of interpenetrating motifs, symmetric and topological properties of interpenetrating systems is given. The main advances of crystal chemistry in the systematization of interpenetrating structures are elucidated. It is noted that the major trend in the crystal chemistry of interpenetration is the development of methods for the topological classification of the entanglements of interpenetrating groups and the search for the regularities of their implementation in crystalline substances. The main ways of the formation of interpenetrating structures, the appearing here geometrical-topological restrictions, and also the effect of stereochemical factors and synthesis conditions on the possibility of interpenetration are considered

New Types of Multishell Nanoclusters with a Frank\u2013Kasper Polyhedral Core in Intermetallics

A comprehensive study of the occurrence of two-shell clusters with the first shell as a Frank-Kasper polyhedron Z12, Z14, Z15, or Z16 (Frank-Kasper nanoclusters) is performed for 22951 crystal structures of intermetallics containing only metal atoms. It is shown that besides the familiar Bergman and Mackay clusters, two more types of high-symmetrical icosahedron-based nanoclusters are rather frequent; they both have a 50-atom second shell. Moreover, two types of high-symmetrical Frank-Kasper nanoclusters with a Friauf-polyhedron (Z16) core are revealed; these nanoclusters have 44 and 58 atoms in the second shell. On the contrary, Z14 and Z15 Frank-Kasper polyhedra have been found to be rare and improper to form distinct nanoclusters in crystals. The second shells of Frank-Kasper nanoclusters have been revealed possessing their own stability: they can be realized in nanoclusters with different internal polyhedra and can shift around the core shell. The role of Frank-Kasper nanoclusters in assembling intermetallic crystal structures is illustrated by several examples

The Zeolite Conundrum : Why Are There so Many Hypothetical Zeolites and so Few Observed? A Possible Answer from the Zeolite-Type Frameworks Perceived As Packings of Tiles

In the attempt to explain why there are so many hypothetical zeolites and so few observed, a model of assembling zeolite-type frameworks as a packing of natural building units (smallest cages) and/or essential rings (smallest windows) is proposed. The packing units have no common T atoms, hence the model takes into account the process of polycondensation of T4+(OH)4 or [T3+(OH)4] 12 complex groups resulting in oligomeric TnOm(OH)k units, eliminating water molecules, and forming T 12O 12T bridges. The packings were modeled for all zeolite minerals and most of the synthetic zeolite-type frameworks accounting for 163 zeolites of the 201 known. It is shown that the extra-framework cations can play a role of templates for the packing units. Application of the model to 1220 hypothetical zeolites shows that only a small set could be explained as packing of tiles, suggesting a possible ranking of feasibility that may help to unravel the zeolite conundrum

Interpenetrating metal\u2013organic and inorganic 3D networks: a computer-aided systematic investigation. Part I. Analysis of the Cambridge structural database

The occurrence of interpenetration in metal\u2013organic and inorganic networks has been investigated by a systematic analysis of the CSD and ICSD structural databases. For this purpose, a novel version of TOPOS (a program package for multipurpose crystallochemical analysis) has been employed, where the procedure of recognition of interpenetrating nets is based on the representation of a crystal structure as a finite reduced graph. In this paper we report a comprehensive list (301 Refcodes) of interpenetrating metal\u2013organic 3D structures from CSD, that are analyzed on the basis of their topologies. Interesting trends and novel features have been observed and distinct classes of interpenetrating nets have been envisaged, depending on the relationships of the individual motifs