Table 2.

Data for crystalline ordering obtained from single-crystal X-ray diffraction.

Material	Interplanar π–π distance (Å)	Intermolecular π–π (centroid–centroid) distance (Å)	N—H—O bond length (Å)	Packing pattern	Space group
DPP	3.3 (along a) 3.0 (along b)	3.817 (along a) 6.516 (along b)	1.816	Brick-wall	P–1
p-Cl–DPP	3.0 (along a) 3.3 (along c)	5.658 (along a) 5.585 (along c)	1.740	Pseudo-brick-wall	P21/n
p-Br–DPP	3.2 (along b) 3.2 (along a)	5.628 (along b) 5.628 (along a)	1.770	Pseudo-brick-wall	C2/c