The pyrene nucleus is a valuable component for materials, supramolecular and biological chemistry, due to its photophysical/electronic properties and extended rigid structure. However, its exploitation is hindered by the limited range of methods and outcomes for the direct substitution of pyrene itself. In response to this problem, a variety of indirect methods have been developed for preparing pyrenes with less usual substitution patterns. Herein we review these approaches, covering methods which involve reduced pyrenes, transannular ring closures and cyclisations of biphenyl intermediates. We also showcase the diverse range of substituted pyrenes which have been reported in the literature, and can serve as building blocks for new molecular architectures.

[structure: see text] We report two methods for the attachment of mono- and disaccharides to one or both of the cyclopentadienyl rings in ferrocene. The first strategy involves the reaction in acidic media of thioglycosides with ferrocenemethanol or 1,1'-ferrocenedimethanol. The second method consists of the regiospecific catalytic cycloaddition of propargyl glycoside and azidomethyl and bis(azidomethyl)ferrocene leading to the 1,2,3-triazole derivatives. The inverse strategy was also explored. The electrochemical behavior of the synthesized ferrocene-containing glycoconjugates was investigated.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms A threading receptor for polysaccharides Polysaccharides are the dominant organic molecules in the biosphere 1 , and thus key renewable resources 2,3 . However the most abundant, including cellulose and chitin, are generally the most difficult to utilise due to extreme insolubility. At present there is no method for mobilising these materials in water under mild conditions, so that modifications involve chemical transformations in aggressive media [4][5][6] or the slow action of enzymes on undissolved solids 7 . Dissolution in aqueous media at biological pH would allow new paths to exploitation. In particular, the polysaccharides could be exposed to enzymes, either natural or engineered, to which they would be far more vulnerable. The rapid conversion of cellulose to glucose is just one prospective outcome.Here we adumbrate a strategy for the dissolution of cellulose, and related polysaccharides, through the application of synthetic receptors. The approach employs cage molecules with amphiphilic interiors, complementary to the carbohydrate targets. Critically the receptors are able to thread onto the polysaccharides, forming polypseudorotaxanes 8,9 . Because of the threaded topology, many receptor molecules can bind to one polysaccharide chain, surrounding the polymer with hydrophilic groups. If binding is sufficiently strong to counteract crystal packing forces, dissolution should be feasible. We report the design and synthesis of a threading receptor for polysaccharides, and show that it forms pseudorotaxanes with water-soluble oligosaccharides.We also describe evidence for polypseudorotaxane formation from polysaccharides under certain conditions. The results demonstrate the feasibility of polysaccharide threading in water, and could point the way to systems capable of solubilisation.A defining feature of cellulose 1 and chitin 2 (Fig. 1a) is the all-equatorial disposition of intra-chain linkages and polar substituents and (consequently) the axial positioning of apolar CH groups. In the extended conformation of the polymer, this creates two parallel strips of hydrophobic surface separated by lines of hydrogen-bonding functional groups. Our strategy for complementing these supramolecular valencies is illustrated in Fig. 1b. We sought a cage-like receptor structure in which two aromatic surfaces would be held parallel to each other, separated by rigid, polar spacers. The portals of the cage would be large enough to allow threading by the polysaccharide substrates. The aromatic surfaces would be capable of forming hydrophobic and CH-π interactions with axial CH groups in the substrates, while polar groups would hydrogen bond to equatorial substituents.We had previously used a related approach to bind all-equatorial mono-and di-saccharides in water 10-13 .However, these earlier designs e...