Probing the structure of framework materials by high pressure and the example of a magnetic, non-porous coordination polymer

Abstract

Nestled between the modest pressures employed to study protein folding (a few hundred megapascals) and the very high pressures obtained in shock-wave experiments (in the order of terapascals), a vast pressure scale can be explored experimentally and computationally in the physical and life sciences. Pressure is a powerful thermodynamic variable that enables the structure, bonding and reactivity of matter to be altered. In materials science it has become an indispensable research tool in the quest for novel functional materials. Examples include the target synthesis of new classes of materials with unique physical properties, see for instance the recently reported ultra-thin 'diamond nanothreads' obtained by decompressing benzene from 20 GPa to ambient pressure (Fitzgibbons et al., 2015). Materials scientists can exploit the effectiveness of pressure for probing and tuning structural, mechanical, electronic, magnetic and vibrational properties of materials in situ; crystallography plays a crucial role here, enabling on one hand the unravelling of structural phenomena through a better understanding of interactions, and on the other hand the derivation of structure-property relationships.Crystalline framework materials have long established themselves as the subject of intense interdisciplinary research activity; several classification systems and topological descriptors exist and the terminology found in the literature is rich and varied. In the simple and somewhat arbitrary view of this author, these materials can be divided into two main classes based on property, namely materials that exhibit porosity and those that do not. Porosity allows for potential applications in, inter alia, energy storage, catalysis, separation and capture technologies. Examples of industrially relevant framework materials displaying porosity include zeolites, at the forefront of the family of inorganic open-framework materials (Cheetham et al., 1999), and metal-organic frameworks (MOFs), which in the literature appear under the heading of hybrid inorganic organic framework materials (Cheetham et al., 2006) and, following the preferred definition by IUPAC (Batten et al., 2012(Batten et al., , 2013, under the heading of coordination networks, a subclass of coordination polymers. In the past decade MOFs have sparked an international frenzy of research activity. Porous framework materials have been widely investigated by highpressure crystallography: zeolites have been recently reviewed (Gatta & Lee, 2014) and a review on the subject of 'MOFs under high pressure' by S. A. Moggach will appear later in 2015 as a feature article in Acta Crystallographic Section B. In a very recent perspective in Chemistry of Materials, Coudert (2015) provides an inspiring overview of porous and non-porous 'stimuli-responsive' framework materials, i.e. those framework materials that by virtue of their flexibility undergo marked structural changes ('changes of large amplitude') in response to external stimuli such as pressure, temperature or light.High-pressur...

Helical Coordination Polymers Based on A Tripodal N‐donor Ligand

“…Coordination polymers (CPs), based on the potential applications in gas adsorption and separation, optical devices, magnetism, heterogeneous catalysis, drug delivery etc., have been rapidly developed in the realm of supramolecular chemistry and crystal engineering in recent years 1–15. In order to attain various structures and different topologies, considerable efforts have been put into the design and construction of CPs.…”

Piezochromic Topology Switch in a Coordination Polymer

“…High pressure is a method capable of efficiently generating a variety of effects, such as polymorphism, , amorphization, − piezochromism, − and others. − Reversible − and permanent , transitions and their different applications were reported; also the “hidden” polymorphs obtained only by in situ recrystallization in their stability region were found. , The experimental techniques developed in recent few years opened new perspectives for producing functional materials under extreme conditions, for example, novel magnetic , or photomagnetic phases . Several 3D MOF architectures were studied as a function of pressure and temperature in the search for unusual elastic properties, such as negative compression and negative thermal expansion. − For example, it was postulated that the negative linear compression of crystal structures is characteristic of the wine-rack type of frameworks .…”

“…24−26 Reversible 27−30 and permanent 31,32 transitions and their different applications were reported; also the "hidden" polymorphs obtained only by in situ recrystallization in their stability region were found. 33,34 The experimental techniques developed in recent few years opened new perspectives for producing functional materials under extreme conditions, for example, novel magnetic 35,36 or photomagnetic phases. 37 Several 3D MOF architectures were studied as a function of pressure and temperature in the search for unusual elastic properties, such as negative compression and negative thermal expansion.…”