Table 2. Hydrogen-bonding geometry (Å) for compound HEA-pABA.

No. of HB	D−H…A	d(D…H), Å	d(H…A), Å	d(D A), Å	∠(DHA), deg.	Symmetry transformation for H-acceptor
1	N(1)–H…O(3)	0.89	1.91	2.801(3)	175	−x+2, −y, −z+2
2	N(1)–H…N(2)	0.89	2.22	3.051(4)	155	x, −y+1/2, z+1/2
3	N(1)–H…O(2)	0.89	1.87	2.752(3)	171	x, y, z
4	O(1)–H…O(3)	0.82	1.90	2.715(3)	176	x, y, z
5	N(2)–H…O(1)	0.91(3)	2.29(3)	3.087(3)	146	−x+2, y−1/2, −z+1/2
6	N(2)–H…O(3)	0.82(3)	2.20(3)	3.025(3)	174	x+1/2, y, −z+1/2
7	C(2)–H…O(2)	0.97	2.41	3.247(3)	145	x−1/2, −y+1/2, −z+1