Table 3. Experimental details.

	(I)	(II)	(III)	(IV)
Crystal data
Chemical formula	C11H8N2O4	C13H12N2O4	C14H14N2O4	C12H14N6O3
M r	232.19	260.25	274.27	290.29
Crystal system, space group	Orthorhombic, P b c a	Monoclinic, P21/n	Triclinic, P	Monoclinic, P21/n
Temperature (K)	296	296	296	296
a, b, c (Å)	13.164 (2), 7.4692 (9), 21.173 (3)	5.9000 (4), 14.5273 (12), 14.8726 (12)	7.6546 (5), 8.0959 (5), 11.3065 (6)	7.6030 (6), 22.6605 (19), 7.6751 (7)
α, β, γ (°)	90, 90, 90	90, 98.867 (3), 90	78.988 (3), 85.527 (3), 87.548 (4)	90, 102.284 (3), 90
V (Å3)	2081.8 (6)	1259.51 (17)	685.40 (7)	1292.05 (19)
Z	8	4	2	4
Radiation type	Mo Kα	Mo Kα	Mo Kα	Mo Kα
μ (mm−1)	0.12	0.10	0.10	0.11
Crystal size (mm)	0.16 × 0.14 × 0.11	0.17 × 0.14 × 0.13	0.16 × 0.15 × 0.12	0.14 × 0.13 × 0.11
Data collection
Diffractometer	Bruker Kappa APEXII CCD	Bruker Kappa APEXII CCD	Bruker Kappa APEXII CCD	Bruker Kappa APEXII CCD
Absorption correction	Multi-scan (SADABS; Sheldrick, 2008a ▸)	Multi-scan (SADABS; Sheldrick, 2008a ▸)	Multi-scan (SADABS; Sheldrick, 2008a ▸)	Multi-scan (SADABS; Sheldrick, 2008a ▸)
T min, T max	0.931, 0.987	0.960, 0.987	0.955, 0.988	0.929, 0.988
No. of measured, independent and observed [I > 2σ(I)] reflections	31526, 2218, 1304	21653, 2704, 1624	12818, 2526, 1777	20456, 2521, 1722
R int	0.063	0.046	0.030	0.053
(sin θ/λ)max (Å−1)	0.634	0.635	0.605	0.618
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.045, 0.122, 1.03	0.042, 0.129, 1.04	0.044, 0.128, 1.05	0.046, 0.108, 1.05
No. of reflections	2218	2704	2526	2521
No. of parameters	161	175	196	210
No. of restraints	0	0	7	0
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement	H-atom parameters constrained	H-atom parameters constrained	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.19, −0.16	0.19, −0.18	0.24, −0.24	0.20, −0.21

Computer programs: APEX2, SAINT and XPREP (Bruker, 2004 ▸), SHELXS97 (Sheldrick, 2008b ▸), SHELXL2014 (Sheldrick, 2015 ▸) and PLATON (Spek, 2009 ▸).