N,N'-(((Ethane-1,2-diylbis(oxy))bis(methylene))bis(6-oxo-6,9-dihydro-1H-purine-9,2-diyl))diacetamide; N,N'-(9,9'-((Ethane-1,2-diylbis(oxy))bis(methylene))bis(6-oxo-6,9-dihydro-1H-purine-9,2-diyl))diacetamide