Abstract: The present invention relates to chemical linkers and protecting groups, compounds and compositions containing the chemical linkers or protecting groups, and intermediates and processes that can be used to prepare them. The chemical linkers and protecting groups are based on pyrrolidine and piperidine activating groups, which undergo intramolecular cyclisation upon heating with release of carbon dioxide, thereby releasing the organic compound from a substrate. In particular, those chemical linkers and protecting groups are useful in the solid phase synthesis of oligonucleotides according to the following representative schemes.

Abstract: A method of creating a mask on a surface of a substrate is disclosed. The substrate comprises a plurality of spaced heating elements on or proximal to the surface. The method comprises applying a layer of masking material to the surface and employing the heating elements to apply energy to a phase change in the masking material at the selected sites such that it adheres to the surface or can be displaced from the surface to mask or unmask the selected sites respectively. A method of synthesising an array of molecules, an apparatus for selectively masking one or more sites on a surface and a semi-conductor chip that uses micro-heaters to modulate a masking layer on areas of the chip surface.