AbstractThe gas-phase basicities of a group of multidentate polyamines have been determined by the bracketing method and range from 966 to 1021 kJ/mol. The compounds studied vary in the number and kind of basic sites, the number and orientation of carbon atoms, and the degree of flexibility. These important structural features were analyzed to understand the observed trends in basicity and semiempirical calculations were undertaken that support the experimental trends. The polyamines may find use as reference compounds for future gas-phase basicity measurements of larger, biologically active molecules such as peptides and proteins