1H NMR and X-ray crystallographic analysis of 1,2-bis(4,6-diethylthio-1H-pyrazolo[3,4-d]pyrimidin-1-yl)ethane and its ‘propylene linker’-analog: molecular recognition versus crystal engineering

Proton NMR analysis on newly synthesized 1,2-bis(4,6-diethylthio-1H-pyrazolo[3,4-d]pyrimidin-1-yl)ethane, 2c, and 1,2-bis(4,6-diethylthio-1H-pyrazolo[3,4-d]pyrimidin-1-yl)propane, 2d, showed intramolecular stacking in solution. X-Ray crystallography on 2c and 2d, however, confirmed the presence of such intramolecular stacking only in case of the ‘propylene linker’ compound, 2d, while the ‘ethylene linker’ compound, 2c, was devoid of it.