the synthetic 9- [ 3- ( aden-9-yl ) propyl ] -6- ( 3-methyl-2-butenylamino ) purine , ad-c ( 3 ) -ipad ( iv ) , in which the adenine and n ( 6 ) -substituted adenine moieties are joined at the 9 and 9 ' positions by a trimethylene chain , served as a useful spectroscopic model for assessing the base-base interaction free from the complicating features of the carbohydrate and phosphodiester groupings .
C0034140
purine
C0001407
adenine