Hydrogen-bonded template

Hydrogen-Bonding Templates in Dynamic Combinatorial Libraries 120... 

Hydrogen-Bonding Templates in Self-Replicating Systems. 125... 

In the following sections, examples of hydrogen-bonding templates for the synthesis of macrocycles, cages, interlocked species, helicates and for the photochemical reaction of olefins will be discussed. The use of hydrogen-bonding templates in dynamic combinatorial libraries will also be presented. 

Scheme 10 Leigh has reported the hydrogen-bonding templated synthesis of catenane 15...

Scheme 11 Hydrogen-bonding templated preparation of catenane 18 under thermodynamic control...

Scheme 14 [3]Rotaxane 23 can be prepared by hydrogen-bonding templated synthesis employing the threading-followed-by-capping methodology...

Scheme 16 Synthesis of [3]rotaxane 27 by hydrogen-bonding templated synthesis... 

Assembly of Rotaxanes by an "Independent" Hydrogen-Bonding Template... 

Few examples of covalent and non-covalent DCLs have been reported over the past few years, with only a small number of them making use of hydrogen-bonding templates. One of such examples is the barbiturate receptor 73 reported by... 

Lehn has also reported the hydrogen-bonding templated assembly of receptors based on bipyridine copper and palladium complexes [102]. A mixture of substituted bipyridines (76, 77) (see Scheme 39) with copper(I) triflate generates a mixture of tetrahedral complexes and uncoordinated ligands. 

Khan A, Haddleton DM, Hannon MJ, Kukulj D, Marsh A. Hydrogen bond template-directed polymerization of protected 5 -acryloylnucleosides. Macromolecules 1999 32 6560-6564. 

Figure 26. The hydrogen-bonding template-directed syntheses of the [2]catenanes 78 and 80.

Recent work by Len MacGillivray of the University of Iowa, USA, has used topochemistry to produce an impressive range of new solid compounds by the addition of hydrogen bonded templates in order to bring about the designer orientations of photochemically reactive molecules in the solid state.34 A simple example is the use of resorcinol (1,3-dihydroxybenzene) to position two molecules of trans 1,2 bis (4-pyridyl) ethylene with their double bonds overlapping at ca. 4 A as required by the topochemical postulate. Upon photolysis the product rcfHetrakis(4-pyridyl)cyclobutane is formed stereospecifically and in 100 % yield, Scheme 8.2. In the absence of the resorcinol template trans-l,2-bis(4-pyridyl) ethylene is... 

The functionalisation also allows extending the complexity of intertwined molecular assemblies involving molecular catenanes, rotaxanes and knots. Elaborate interlocked assemblies constructed by means of metal-templation techniques and ji-ji-stacking preorganisation were reviewed [3, 11], Our last survey was devoted to the hydrogen bond templated synthesis of amide-based catenanes and rotaxanes [32], Since then a considerable advancement in elucidation of mechanisms of templation and derivatisation of the amide-based interlocked structures has been reached. Moreover, in 2000 we reported a one pot synthesis of amide-based knots such as 8 [21], which is so far the easiest preparation of molecular knots. In the following, specific possibilities of functionalisation of amide-based catenanes, rotaxanes and knots will be discussed. 

Figure 4. Hydrogen bond templated threading of a tetraamide ring in synthesis of amide-based catenanes and...

Scheme 10.5 Hydrogen bond-templated self-assembly of [2]catenanes reported by both Vogtle and coworkers and Hunter and coworkers. 

Figure 10.3 Examples of [2]rotaxane formation via hydrogen bond-templated macrocyclization reported by Leigh and coworkers.

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