Anomalous Anisotropic Thermal Expansion in a One-Dimensional Coordination Polymer Driven by Conformational Flexibility

A one-dimensional lithium(I) coordination polymer has been characterized by variable-temperature single-crystal X-ray diffraction and differential scanning calorimetry. This compound possesses an anisotropic packing arrangement that, along with a scissor-like or hingelike movement of the pyridyl ligand side arms, results in an extremely rare combination of positive, negative, and zero thermal expansion. Designing such types of materials and understanding the mechanistic details can facilitate the design of new thermoresponsive materials. © 2015 American Chemical Society.</p

A five-fold interpenetrated metal-organic framework showing a large variation in thermal expansion behaviour owing to dramatic structural transformation upon dehydration-rehydration

A five-fold interpenetrated metal organic framework (MOF) has been shown to exhibit anomalous thermal expansion due to the combined effect of hinge-like motion and sliding of individual diamondoid networks. Upon dehydration, the MOF undergoes dramatic structural changes, thereby altering its thermal expansion behaviour to a large extent. © The Royal Society of Chemistry.</p

Hydration-dependent anomalous thermal expansion behaviour in a coordination polymer

A coordination polymer is shown to possess anomalous anisotropic thermal expansion. Guest water molecules present in the as-synthesised material can be removed upon activation without loss of crystal singularity. The fully dehydrated form shows considerably different thermal expansion behaviour as compared to the hydrate. © The Royal Society of Chemistry 2016.</p

Isolation of a structural intermediate during switching of degree of interpenetration in a metal-organic framework

A known pillared layered metal-organic framework [Co2(ndc)2(bpy)] is shown to undergo a change in degree of interpenetration from a highly porous doubly-interpenetrated framework (2fa) to a less porous triply-interpenetrated framework (3fa). The transformation involves an intermediate empty doubly-interpenetrated phase (2fa′) which has been isolated for the first time for this kind of phenomenon by altering the conditions of activation of the as-synthesized material. Interestingly, all the transformations occur in single-crystal to single-crystal fashion. Changes in degree of interpenetration have not been explored much to date and their implications with regard to the porosity of MOFs still remain largely unknown. The present study not only provides a better understanding of such dramatic structural changes in MOF materials, but also describes an original way of controlling interpenetration by carefully optimizing the temperature of activation. In addition to studying the structural mechanism of conversion from 2fa to 3fa, sorption analysis has been carried out on both the intermediate (2fa′) and the triply-interpenetrated (3fa) forms to further explain the effect that switching of interpenetration mode has on the porosity of the MOF material. © The Royal Society of Chemistry.</p

Erratum: A combined stretching-tilting mechanism produces negative, zero and positive linear thermal expansion in a semi-flexible Cd(ii)-MOF (Chemical Communications (2014) (50) (6464-6467) DOI: 10.1039/C4CC02634A)

Correction for 'A combined stretching-tilting mechanism produces negative, zero and positive linear thermal expansion in a semi-flexible Cd(ii)-MOF' by Prem Lama et al., Chem. Commun., 2014, 50, 6464-6467. The authors regret that incorrect values were given in Table 2 of the original article. The correct version of Table 2 is given below. (Table Presented). © 2018 The Royal Society of Chemistry.</p