You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
58 Chapter 4<br />
4.1 Introduction<br />
4.1.1 Solid solutions<br />
Among the well-known mixed-component MOFs, the class of MOF solid solutions (also<br />
known as molecular substitutional alloys) attract huge attention. It implies MOFs where to<br />
two or more types of the related components (either linkers, metals, or both) are<br />
randomly mixed within single-phased framework. Remarkably, this often allows the fine<br />
modulation of the MOF’s functionalities and properties. Considering the nature of the<br />
mixed components, MOF solid solutions could be sub-divided mainly into two groups:<br />
linker-based and metal-based MOF solid solutions. The first group covers MOF solids<br />
where two or more homologous linkers (usually of similar size and functionality) are<br />
integrated in various proportions while the structural integrity of MOF is preserved. The<br />
metal-based MOF solid solutions will be discussed in details in Chapter 5 and involve<br />
mixed-metal frameworks where ions of one metal type is partly isomorphous substituted<br />
by the other metal ions.<br />
Figure 4.1. Mixed-linker approaches to the formation of MOF solid solutions. Magenta balls, metal<br />
nodes; cyan sticks, parent linker; green sticks, isostructural mixed-linker; wine short sticks,<br />
truncated mixed-linker; violet sticks, heterostructural mixed-linker. Inspired by the reports of<br />
Bunck [127] and Fang et al. [137]<br />
Approaches for the synthesis of linker-based MOF solid solutions go basically into three<br />
directions depending on the utilized linker mixtures (Figure 4.1): [127]<br />
i) isostructural mixed-linker (IML) approach where mixed linkers feature identical linking<br />
geometry. [123-124, 209-212]