Table 3. Experimental details.

	(I)	(II)
Crystal data
Chemical formula	C18H14N4O4	C20H18N4O4
M r	350.33	378.38
Crystal system, space group	Monoclinic, I a	Tetragonal, I41/a
Temperature (K)	293	223
a, b, c (Å)	8.4249 (12), 12.2465 (10), 16.2561 (13)	10.2295 (6), 10.2295 (6), 36.281 (3)
α, β, γ (°)	90, 103.730 (8), 90	90, 90, 90
V (Å3)	1629.3 (3)	3796.5 (5)
Z	4	8
Radiation type	Mo Kα	Mo Kα
μ (mm−1)	0.10	0.10
Crystal size (mm)	0.70 × 0.50 × 0.38	0.65 × 0.50 × 0.50
Data collection
Diffractometer	Stoe–Siemens AED2	Stoe IPDS 1
No. of measured, independent and observed [I > 2σ(I)] reflections	3035, 3028, 2737	14760, 1851, 1153
R int	0.012	0.043
(sin θ/λ)max (Å−1)	0.606	0.616
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.050, 0.135, 1.11	0.049, 0.149, 1.01
No. of reflections	3028	1851
No. of parameters	238	129
No. of restraints	2	0
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.19, −0.21	0.34, −0.19

Computer programs: STADI4 (Stoe & Cie, 1997 ▸), EXPOSE, CELL and INTEGRATE in IPDS-I (Stoe & Cie, 2004 ▸), X-RED (Stoe & Cie, 1997 ▸), SHELXS97 (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸), PLATON (Spek, 2009 ▸), Mercury (Macrae et al., 2008 ▸), and publCIF (Westrip, 2010 ▸).