The photolabile hydrazine linker of the present invention is based on the o-nitro-veratryl group, which is capable of releasing hydrazide derivatives upon UV irradiation. The linker allows for a new solid-phase peptide synthesis (SPPS) strategy which is fully orthogonal to the most commonly used protecting groups and chemical methods in SPPS and shows excellent compatibility with peptide composition, notably the 20 naturally occurring α-amino acid residues (even in their side-chain protected form) are accepted in the C-terminal of the peptide hydrazides. Furthermore, the linker unit can be applied to synthesize combinatorial libraries of biological interesting heterocyclic compounds, such as pyranopyrazoles.