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Activating [4+4] photoreactivity in the solid-state via complexation: from 9-(methylaminomethyl)anthracene to its silver(I) complexes.
Get PDFThe [4 + 4] photoreactivity of the anthracene derivative 9-(methylaminomethyl)anthracene (MAMA) has
been investigated in solution, gel medium and in the solid state. While quantitative formation of the
cyloaddition photoproduct was achieved upon irradiation at λ = 365 nm of ethanol solutions of MAMA,
only partial and slow conversion was detected in gels of low molecular weight gelators, and solid-state
reactivity was not observed due to the unfavourable relative orientation of the anthracene moieties in the
crystal. In hexafluorophosphate, tetrafluoroborate and nitrate silver(I) complexes, however, 9-(methylaminomethyl)
anthracene exhibits a more favourable mutual orientation for the aromatic fragments, and
[4 + 4] photoreactivity resulted. All compounds were structurally characterized via single crystal and/or
X-ray powder diffraction and by Raman spectroscopy; this last technique proved effective in detection of
the photoproduct in all solid state complexes
Reactions in solid-state inclusion compounds
No full textThis chapter focuses on chemical reactions occurring within solid organic inclusion compounds, encompassing a broad range of inclusion compounds and a wide variety of different reaction types, including reactions of the guest molecules (such as dimerization, polymerization, cyclization, isomerization, and decomposition), reactions involving the host molecules, and guest exchange processes. In many cases, chemical transformations of guest molecules confined within solid host structures proceed with a high degree of selectivity toward a single product, and often with a high degree of stereoselectivity and/or enantioselectivity, as a consequence of the geometrical constraints imposed on the reacting molecules by the host structure. For this reason, the products obtained from such reactions are often significantly different from those obtained from the corresponding reactions in the solution state or in the “pure” crystalline phase of the guest molecules. Through the examples highlighted in this chapter, general issues relating to reactions in solid organic inclusion compounds are rationalized and discussed
Chirality
No full textThis chapter addresses stereochemical consequences in supramolecular chemistry in terms of both the components and the ultimate assembly. In particular, it discusses the important (and sometimes elusive) concept of chirality in supramolecular aggregates—its origin, the practical aspects of separation of chiral forms and their identification and quantification. The examples taken are predominantly from metallosupramolecular systems: the deliberate construction of chiral oligonuclear assemblies as well as the principles that guide the phenomenon of self-assembly of the components, which give rise to (inter alia) helicates, catenanes, knots, and polygons—many of which are inherently chiral. Because of the possible variations of structural motifs—in terms of both metal centers and their geometries, and of ligand types—metallosupramolecular chemistry can realize an extraordinary range of assemblies, which are not only elegant in design and varied in nature but also provide the potential for the development of new materials in nanoscience
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