Back Zwitterioon Afrikaans أيون مزدوج Arabic Цвитерйон Bulgarian Dvopolarizirani ion BS Zwitterió Catalan Zwitterion Czech Zwitterion German Αμφιτεριόν Greek Zuiterjono Esperanto Zwitterión Spanish
In chemistry, a zwitterion (/ˈtsvɪtəˌraɪən/ TSVIT-ə-ry-ən; from German Zwitter [ˈtsvɪtɐ] 'hermaphrodite'), also called an inner salt or dipolar ion,[1] is a molecule that contains an equal number of positively and negatively charged functional groups.[2] (1,2-dipolar compounds, such as ylides, are sometimes excluded from the definition.[3])
Some zwitterions, such as amino acid zwitterions, are in chemical equilibrium with an uncharged "parent" molecule. Betaines are zwitterions that cannot isomerize to an all-neutral form, such as when the positive charge is located on a quaternary ammonium group. Similarly, a molecule containing a phosphonium group and a carboxylate group cannot isomerize.
- ^ "Zwitterion". Chemistry LibreTexts. 2015-11-03. Archived from the original on 2023-06-21. Retrieved 2022-02-11.
- ^ Skoog, Douglas A.; West, Donald M.; Holler, F. James; Crouch, Stanley R. (2004). Fundamentals of Analytical Chemistry (8th ed.). Thomson/Brooks/Cole. pp. 231, 385, 419, 460. ISBN 0-03-035523-0.
- Fundamentals of Analytical Chemistry (9th ed.). 2013. pp. 415–416. ISBN 978-1-285-60719-1.
- ^ IUPAC, Compendium of Chemical Terminology, 5th ed. (the "Gold Book") (2025). Online version: (2006–) "Zwitterionic compounds/zwitterions". doi:10.1351/goldbook.Z06752