Home Physical Sciences Crystal structure of 4-(4-(quinolin-8-yloxy)-1,2,5-thiadiazol-3-yl)morpholine, C15H14O2N4S
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Crystal structure of 4-(4-(quinolin-8-yloxy)-1,2,5-thiadiazol-3-yl)morpholine, C15H14O2N4S

  • Mokete A. Motente ORCID logo EMAIL logo , Uche A. K. Chude-Okonkwo , Orpah Zinyemba and Dumisane V. Kama
Published/Copyright: October 10, 2025

Abstract

C15H14O2N4S, monoclinic, P21/n (no. 14), a = 7.4484(6) Å, b = 17.3543(15) Å, c = 11.7814(9) Å, β = 106.377(3)°, V = 643.50(8) Å3, Z = 4, Rgt(F) = 0.0853, wRref(F2) = 0.0871, T = 100 K.

CCDC no.: 2492772

The molecular structure is shown in the figure. Table 1 contains the crystallographic data. The list of the atoms including atomic coordinates and displacement parameters can be found in the cif-file attached to this article.

Table 1:

Data collection and handling.

Crystal: Yellow block
Size: 0.19 × 0.12 × 0.10 mm
Wavelength: Mo Kα radiation (0.71073 Å)
μ: 0.24 mm−1
Diffractometer, scan mode: Bruker Apex-II, φ and ω-scans
θmax, completeness: 28.4°, > 99 %
N(hkl)measured, N(hkl)unique, Rint: 32252, 3621, 0.047
Criterion for Iobs, N(hkl)gt: Iobs > 2σ(Iobs), 3399
N(param)refined: 199
Programs: Shelx, 1 Bruker programs, 2 Olex2, 3 Diamond 4

1 Source of materials

The title compound was synthesized by dissolving (200 mg, 1.38 mmol) of 8-hydroxyquinoline and (353 mg, 1.53 mmol, 1.10 equiv) of 4-(4-chloro-1,2,5-thiadiazol-3-yl)morpholine in 10 mL of anhydrous DMF under nitrogen. An amount of 910 mg (2.80 mmol, 2 equiv) of cesium carbonate was added to the reaction mixture, and the reaction was stirred at 120 °C for 18–24 h, monitored by TLC. Upon completion, the reaction was cooled, poured into 20 mL of water, and extracted with ethyl acetate (3 × 20 mL). The combined organic layers were washed with brine, dried over anhydrous sodium sulfate (Na2SO4), filtered, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography using ethyl acetate:hexane (3:7), and the product was recovered as a light-yellow solid. The product was dissolved in 5 mL of acetone and left to crystallize, resulting in the formation of light-yellow crystals.

2 Experimental details

All H-atoms were positioned on geometrically idealized positions and refined using the riding model with fixed C–H distances for aromatic C–H of 0.95 Å (C–H) [Uiso(H) = 1.2 Ueq]. The graphics were obtained using the DIAMOND 4 program with 50 % probability ellipsoids.

3 Comment

The molecular structure of 4-(4-((1,2-dihydroquinolin-8-yl)oxy)-1,2,5-thiadiazol-3-yl) morpholine was elucidated by single-crystal X-ray diffraction. The thiadiazole ring exhibits nearly identical S–N bond lengths of S1–N2 1.6493(10) Å and S1–N3 1.6534(10) Å, consistent with delocalization across the heteroaromatic system. These values are in good agreement with reported bond lengths for neutral thiadiazole derivatives, which typically range from 1.64 to 1.68 A. 5 The short N2–C10 1.3024(13) Å and N3–C11 1.3211(14) Å bond distances indicate pronounced double-bond character. The S1–N2–C10 106.62(8)° and S1–N3–C11 107.82(8)° bond angles are notably smaller than the ideal 120° value, reflecting angular compression common in five-membered thiadiazole systems. 6 The quinoline fragment shows bond distances characteristic of aromatic heterocycles, with N1–C2 1.3657(13) Å and N1–C3 1.3140(15) Å bond distances both consistent with partial double-bond character. The C3–N1–C2 bond angle of 116.67(9)° is consistent with sp2 hybridization, and the C–C bond distances (1.36–1.42 A) also fall within the range expected for conjugated heteroaromatic rings. 7 The morpholine ring adopts a chair conformation, with N–C distances of N4–C11 1.3823(13) Å, N4–C12 1.4733(14) Å, and N4–C15 1.4657(14) Å. These values correspond closely to those reported for other morpholine-containing compounds. 8 , 9 Bond angles around N4, such as C11–N4–C12 116.63(9)° and C11–N4–C15 114.87(9)°, confirm slightly distorted tetrahedral geometry, which is frequently observed due to conformational strain in six-membered heterocycles. 8 The ether linkage connecting the quinoline and thiadiazole fragments is defined by O1–C10 1.3586(13) Å and O1–C1 1.3959(12) Å bond distances. These distances fall within the typical range for aryl–O-alkenyl bonds, while the C10–O1–C1 bond angle is 115.08(8)°. 10


Corresponding author: Mokete A. Motente, Institute for Artificial Intelligent Systems, University of Johannesburg, Johannesburg, 2092, South Africa, E-mail:

Acknowledgements

University of Johannesburg is highly acknowledged for funding.

References

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Received: 2025-08-21
Accepted: 2025-10-02
Published Online: 2025-10-10
Published in Print: 2025-12-17

© 2025 the author(s), published by De Gruyter, Berlin/Boston

This work is licensed under the Creative Commons Attribution 4.0 International License.

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