A β-D-N-acetylglucosamine (GlcNAcβ) ligand equipped with a free thiol through a hydrophilic PEG3 spacer. The thiol reacts with maleimides to form stable thioether conjugates or with other thiols to form disulfide bonds; it is also compatible with thiol-gold chemistry for surface immobilization. This compound provides a β-N-acetylglucosamine (GlcNAcβ) building block for glycoconjugate synthesis and the construction of probes for GlcNAc-recognizing proteins and lectins; it is also relevant to O-GlcNAc and N-glycan biosynthesis research and a substrate for galactosyltransferases.