Organic arsenic(V) compounds typically feature the functional groups R-AsO(OH)2 or R2-AsO(OH) (R = alkyl or aryl). Arsenic compounds such as arsenobetaine, the arsenic analog of betaine (trimethylglycine) has applications in chromatography, separations, and environmental chemistry. Arsenic compounds also have uses in materials science in polymers, proton-exchange membranes, and optical materials. The AsO(OH)2 group is capable of exchanging two protons, very similar to a phosphonic acid, and lower in acidity than a sulfonic acid. Some arsenic compounds also possess anticancer and antimicrobial activity.