Shape-persistent macrocycles

Dendritic branching, starting from shape-persistent macrocycles, with branches extending into the interior of the rings instead of protruding outwards (i.e. intraannular branches), could become accessible. 

Ru(II) AND Os(II) COMPLEXES OF A SHAPE-PERSISTENT MACROCYCLIC LIGAND SYNTHESIS, PHOTOPHYSICAL PROPERTIES, AND... 

Much attention is currently devoted to the synthesis and properties of shape-persistent macrocycles[l]. Such compounds are interesting for a variety of reasons including formation of columnar stacks potentially capable of performing as nanopores for incorporation into membranes or for the generation of nanowires[2]. Furthermore, in shape-persistent macrocycles incorporating coordination units, enc/o-cyclic metal-ion coordination may be exploited to generate nanowires[3], whereas e.ro-cyclic coordination can be used to construct large arrays of polynuclear metal complexes[4]. Shape-persistent macrocycles with reactive substituents may also be linked to other units to yield multicomponent, hierarchical structures. 

As an extension of our previous studies[4,8], we report here the syntheses, the photophysical properties, and the electrochemical chracterization of the shape-persistent macrocyclic ligand 1, containing one bpy unit, and its [Ru(bpy)2(l)]2+ and [Os(bpy)2(l)]2+ complexes (Scheme 1). We also report the syntheses of simpler Ru(II) and Os(II) complexes that together with other previously synthesized species (Scheme 2) have been used as model compounds for interpreting the behavior of the new macrocyclic ligand and its complexes. 

Ru(II) AND Os(II) COMPLEXES OF A SHAPE-PERSISTENT MACROCYCLIC LIGAND SYNTHESIS, PHOTOPHYSICAL PROPERTIES, AND ELECTROCHEMICAL CHARACTERIZATION M. Venturi, V. Balzani, F. Marchioni, D. M. Opris, P. Franke... 

The kinetic approach towards PAMs is carried out mostly and has been used for the synthesis of numerous shape-persistent macrocycles. This approach will be discussed first. The thermodynamic approach has only recently been used for the construction of PAMs and will be discussed afterwards. The intention of this chapter is not a full coverage of all reported synthetic procedures towards shape-persistent macrocycles with nanometer-scale interiors. Rather, typical examples will point up the different existing procedures, including their advantages and disadvantages. 

Scheme 6.7 Shape-persistent macrocycle 56 with an adaptable arrangement of the polar and non-polar side-groups by the intermole-cular acetylene coupling of the corresponding...

As expected, the amount of shape-persistent macrocycle in the crude reaction product depends strongly on the length of the covalent tether (Scheme 6.15)... 

Scheme 6.23 MacLachlan and coworkers synthesis of shape-persistent macrocycles by reversible imine formation.

Although pure aliphatic compounds with a high persistent length are known, as for example [njstaffanes, shape-persistent macrocyclic compounds are dominated by structures with an aromatic backbone. 

Most of the systems described in Chapter 5 contain small- or medium-sized or multinuclear benzenoid and non-benzenoid arenes. In Chapter 6, Hoger gives an overview over the mastery of the synthesis of macro- and megacycles. He shows different approaches towards shape-persistent macrocycles and carefully examines and discusses selected examples that display the advantages and disadvantages of macrocycle synthesis under kinetic and thermodynamic control. The template approach (both supramolecular and covalent) towards functionalized rings is also discussed and introduces a strong motif of supramolecular chemistry, which is much further developed but in a more polymer-oriented topic, in the next chapter. 

Shape-Persistent Macrocycles Based on Acetylenic Scaffolding... 

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