Snapshots of a solid-state transformation: Coexistence of three phases trapped in one crystal

Aromí, G. ; Beavers, C.M. ; Sánchez Costa, J. ; Craig, G.A. ; Mínguez Espallargas, G. ; Orera, A. ; Roubeau, O. (Universidad de Zaragoza)

Resumen: Crystal-to-crystal transformations have been crucial in the understanding of solid-state processes, since these may be studied in detail by means of single crystal X-ray diffraction (SCXRD) techniques. The description of the mechanisms and potential intermediates of those processes remains very challenging. In fact, solid-state transient states have rarely been observed, at least to a sufficient level of detail. We have investigated the process of guest extrusion from the non-porous molecular material Fe(bpp)(H2L)](ClO4)2·1.5C3H6O (bpp = 2,6-bis(pyrazol-3-yl)pyridine; H2L = 2,6-bis(5-(2-methoxyphenyl)-pyrazol-3-yl)pyridine; C3H6O = acetone), which occurs through ordered diffusion of acetone in a crystal-to-crystal manner, leading to dramatic structural changes. The slow kinetics of the transition allows thermal trapping of the system at various intermediate stages. The transiting single crystal can be then examined at these points through synchrotron SCXRD, offering a window upon the mechanism of the transformation at the molecular scale. These experiments have unveiled the development of an ordered intermediate phase, distinct from the initial and the final states, coexisting as the process advances with either of these two phases or, at a certain moment with both of them. The new intermediate phase has been structurally characterized in full detail by SCXRD, providing insights into the mechanism of this diffusion triggered solid-state phenomenon. The process has been also followed by calorimetry, optical microscopy, local Raman spectroscopy and powder X-ray diffraction. The discovery and description of an intermediate ordered state in a molecular solid-state transformation is of great interest and will help to understand the mechanistic details and reaction pathways underlying these transformations.

Idioma: Inglés

DOI: 10.1039/c5sc04287a

Año: 2016

Publicado en: CHEMICAL SCIENCE 7, 4 (2016), 2907-2915
ISSN: 2041-6520

Factor impacto JCR: 8.668 (2016)

Categ. JCR: CHEMISTRY, MULTIDISCIPLINARY rank: 17 / 166 = 0.102 (2016) - Q1 - T1

Factor impacto SCIMAGO: 4.516 - Chemistry (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/MICINN/MAT2011-24284
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2012-32247
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ-2014-59209-P

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)