The present invention provides haloalkane substrates, and linkers for connecting such substrates to functional elements (e.g., tags, labels, surfaces, etc.). Substrates and linkers described herein find use, for example, in labeling, detection, and immobilization of proteins, cells, and molecules. In particular, the linkers provided herein find use within substrates for dehalogenase variants that form covalent bonds with their haloalkane substrates.