Post-functionalisation

Woolfson and Mahmoud have classified the routes to preparation of decorated self-assembling peptide materials [53] as (1) co-assembly, where the functional part is already attached to a self-assembling component prior to assembly, and (2) postassembly, where a non-functionahsed self-assembled structure is modified by covalent or non-covalent means. This discussion adheres to this classification. A third route, beyond the scope of this review, is the use of structured peptides as templates for inorganic materials. Section 4.1 discusses functionalised self-assemblies formed from co-assembly-type approaches, while post-assembly modifications of self-assembled structures are considered in Sect. 4.2. 

Mesoporous solids including silicas and acid-treated clays can be functionalised at their surfaces so as to provide high local concentrations of active sites. These sites can be introduced by post-modification or via sol-gel preparations. In this way a range of novel materials with useful catalytic and other properties can be prepared. One of the most valuable applications for these materials is as replacements for environmentally hazardous reagents including corrosive mineral and Lewis acids, caustic bases and toxic metallic compounds. 

The advantages of all above amide-based assemblies include the electro-neutral character of the compounds, their relative inertness and, last but not least, possibility of their further functionalisation. The latter can be performed both by wise selection of reagents prior to the assembly of an intertwined compound and by its post-assembly derivatisation or by combination of these two methods. The next section discusses the state-of-the-art in derivatising of the amide-based topologies. 

The functionalisation at the N1-position of 2 -deoxy-pseudouridine by Michael addition of methyl acrylate offered access to the phosphoramidites (61). The precursor to (61) was also functionalised as an amine derivative, which was transformed into the fluorescein-labelled phosphoramidites (62a-b). Fluorescent oligonucleotides were synthesised either from these latter building blocks or by post-synthetic modifications of oligomers containing the 2 -deoxy-pseudouridine-1 -propanoate units. ... 

Molecular beacons have also been attached to glass beads. In buffer solution, the beads (containing FAM and methyl red at the termini) are not fluorescent until exposed to co mplementary DNA. Terminus modifiers based on methox oxalamido (MOX) groups (for example the double MOX modifier attached to either a cyclohexane ring (143) or via a 5 -aminothymidine) have been described. The modifiers allow for post-synthesis functionalisation of ODNs. 

The presence of bulky halogens in the 3,3 -positions would disfavor p-coupling, which will result in diminished conductivities, d. The resulting polymers having reactive pendant halogens would readily lend themselves to further functionalisation/modification in the post-polymerisation stage. 

Post-synthetic modification of CMPs opens up a wide range of new functionality that can be incorporated. A strategy recently adopted by Ratvijitvech et al. is to design in functionality specifically for post-synthetic modification. A CMP building block with a pendant amine group was synthesised, which was subsequently used for reaction with anhydrides to produce a series of amide-functionalised networks. ... 

Fig. 22.2 Functionalisation strategies for mesoporous silanol surfaces based on post-caldnation reaction with organosilanes...

The Si02-Al203 monoliths were functionalised either by framework substitution, i.e. incorporation of heteroelements during synthesis, called direct incorporation (DI) or by post-... 

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