1H as well as 13C chemical shifts of 32 compounds of C (3) substituted 2-(n-alkylamino)-3R-naphthalene-1,4-dione (where n-alkyl: methyl, to octyl, R = H, Cl, Br, and CH3) are investigated through 1H, 13C, DEPT, gDQCOSY, and gHSQCAD NMR experiments and M06-2X/6-311++G (d,p) density functional theory are discussed. Single crystal X-ray structure of Br-3, as well as 18 different derivatives of naphthalene-1,4-diones, are revealed for its inter and intra-molecular hydrogen bonding interactions.