Chrystelle Egger

Hybrid open frameworks (MIL-n). Part 5 Synthesis and crystal structure of MIL-9: a new three-dimensional ferrimagnetic cobalt(II) carboxylate with a two-dimensional array of edge-sharing Co octahedra with 12-membered rings

Co 5 (OH) 2 (C 4 H 4 O 4 ) 4 , a new cobalt(II) succinate with an open framework, was prepared hydrothermally (180°C, 72 h, autogenous pressure) from a 2:3:8:120 mixture of Co(II) chloride, succinic acid, potassium hydroxide and water. Its monoclinic structure was solved by single crystal X-ray diffraction [space group P2 1 /c (no. 14) with a=9.5631(2) A, b=9.4538(2) A, c=12.5554(2) A, β=96.968(1)°, V=1126.72(4) A 3 , Z=4] from 3077 unique reflections [I≥2σ(I)], R1=0.020 and wR2=0.054. The three-dimensional structure is built up from layers of edge sharing octahedra pillared by succinate ions. Within the layers, cobalt octahedra form 12-membered ring windows. Below 10 K, Co 5 (OH) 2 (C 4 H 4 O 4 ) 4 , exhibits ferrimagnetic behavior.

Modelling mesoporous materials

Publisher Summary Mesoporous materials of the MCM or SBA variety are by nature organized amorphous materials. To describe their structure, it is necessary to utilize a model that can accommodate both the organization and the disorder. A structural model allows further properties of a phase to be anticipated and also allows the visualization of a structure, which helps understand these novel complex materials. The wall structure of mesoporous materials can be described via an analytical expression. In situations where a mesoporous material is synthesized from a surfactant mesophase based upon a three-dimensional packing of globular micelles, the mathematics based on the exponential scale of a Gaussian distribution works very well. This chapter describes the structure of SBA-1 in this manner; the details of the micellar structure, including oblate distortions of globular micelles, are retained in the final inorganic structure. A preliminary mechanism for a window size in mesoporous materials is also discussed in the chapter.

Understanding the growth mechanism in SBA-1 synthesis

Abstract We have used a combination of time resolved energy dispersive x-ray diffraction, 17 O, 29 Si and 14 N NMR, to examine the kinetics of hydrolysis, organisation and polymerisation in the synthesis of SBA-1. We have also examined the phase diagram for the surfactant used in the preparation, cetyltriethylammonium bromide, by optical polarised light microscopy and 14 N NMR. We establish the order and timing of a number of events in SBA-1 formation.

Targeting formation in microporous and mesoporous materials

Inorganic, ordered microporous and mesoporous materials have utility in a continuum of applications. However, the formation of these materials relies on different, yet overlapping chemistry. As a consequence the tools at our disposal to study the formation mechanisms have to be carefully selected. The goal of this paper is to illustrate some of these techniques using the mesoporous silica SBA-1 as an example with a view to understanding how both structural and kinetic measurements can be married in such a way to produce a consistent picture of the mechanism of formation.

Modelling mesoporous materials with analytical functions

Abstract We have devised a general method for the simple description of a variety of mesoporous structures using analytical functions. These methods are accessible to the synthetic chemist and should allow them to judge the success of the synthesis. In this paper we also use these models as starting points to minimise the structure based upon void volume and curvature using the Surface Evolver program.