Postsynthetic modification characterization

The second route to postsynthetic modification of SAMs is the chemical transformation of functional groups present on their outermost surface this approach mostly relies on chemistries already established for the functionalization of solid supports (Fig. 4.3). Two important points to bear in mind are (1) it is essentially impossible to extensively characterize the structure of the reaction products or purify them without destroying the SAM and (2) many solution-phase reactions may be very difficult when carried out on a surface because of the steric hindrance due to the very closely packed end groups. 

Characterization of zeolites is primarily carried out to assess the quality of materials obtained from synthesis and postsynthetic modifications. Secondly, it facilitates the understanding of the relation between physieal and chemical properties of zeolites and their behaviour in certain applications. For this task, especially, in situ characterization methods have beeome increasingly more important, that is, teehniques whieh probe the zeolite under actual process eonditions. 

Methylation is the only physiological postsynthetic modification of DNA able to modify DNA function and consists in the introduction of methyl groups on cytosines mainly at the CpG dinucleotides of the mammalian genome. This epigenetic modification introduces as fifth base in DNA the 5mC. It is well-known that 5mCs are distributed in a non-random fashion in genomic DNA so that the methylation pattern is characterized by the presence of methylated cytosines on the bulk of DNA while the unmethylated ones are mainly located... 

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