3-(4-Fluoro­phen­yl)imidazo[1,2-a]pyridine-2-carbaldehyde

Guseinov, F.I.; Samigullina, A.I.; Hökelek, T.; Hamidov, S.Z.; Lasri, J.; Hasanov, K.I.; Guliyeva, N.A.; Belay, A.N.

doi:10.1107/S241431462500553X

organic compounds

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ISSN: 2414-3146

Volume 10| Part 6| June 2025| x250553

https://doi.org/10.1107/S241431462500553X

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3-(4-Fluorophenyl)imidazo[1,2-a]pyridine-2-carbaldehyde

Firudin I. Guseinov,^a,^b Aida I. Samigullina,^b Tuncer Hökelek,^c Sahil Z. Hamidov,^d Jamal Lasri,^e Khudayar I. Hasanov,^f Narmina A. Guliyeva ^g and Alebel N. Belay ^h ^*

^aKosygin State University of Russia, 117997 Moscow, Russian Federation, ^bN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation, ^cHacettepe University, Department of Physics, 06800 Beytepe-Ankara, Türkiye, ^dAzerbaijan Technological University, Khatai Avenue, Ganja 2011, Azerbaijan, ^eDepartment of Chemistry, Rabigh College of Science and Arts, King Abdulaziz University, Jeddah 21589, Saudi Arabia, ^fAzerbaijan Medical University, Scientific Research Centre (SCR), A. Kasumzade St. 14, AZ1022 Baku, Azerbaijan, ^gDepartment of Chemical Engineering, Baku Engineering University, Hasan Aliyev str. 120, Baku, Absheron AZ0101, Azerbaijan, and ^hDepartment of Chemistry, Bahir Dar University, PO Box 79, Bahir Dar, Ethiopia
^*Correspondence e-mail: [email protected]

Edited by W. T. A. Harrison, University of Aberdeen, United Kingdom (Received 18 June 2025; accepted 19 June 2025; online 24 June 2025)

In the title compound, C₁₄H₉FN₂O, the dihedral angle between the imidazo–pyridine fused ring system and the pendant fluorophenyl ring is 53.77 (4)°. In the crystal, C—H⋯O and C—H⋯F hydrogen bonds link the molecules into a three-dimensional network. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (30.4%), H⋯C/C⋯H (23.7%), H⋯O/O⋯H (12.2%) and H⋯F/F⋯H (11.1%) interactions.

Keywords: crystal structure; hydrogen bond; Hirshfeld surface.

CCDC reference: 2465675

Structure description

Imidazo[1,2-a]pyridines are an important class of fused N-bridged compounds because of the broad spectrum of synthetic transformations as well as biological activity profiles displayed, which are strongly affected by the substitutions. Several imidazo[1,2-a]pyridines are used clinically, such as the unsubstituted imidazole skeleton cardiotonic agent olprinone, the anticancer agent zolimidine, the 2-substituted analgesic miroprofen, the 3-substituted antiosteoporosis 2,3-disubstituted derivatives with anxiolytic and sedative properties, saripidem, alpidem, and necopidem, and the agent for the treatment of brain disorders and insomnia, zolpidem (Kurteva, 2021 ). As part of our ongoing studies in this area, we now report the synthesis and structure of the title compound (I) (Fig. 1).

Figure 1
The molecular structure of (I) showing 50% probability displacement ellipsoids.

The dihedral angle between the N1/N2/C2/C3/C5–C8/C8A fused ring system (r.m.s. deviation = 0.015 Å) and the pendant C11–C16 fluorobenzene ring is 53.77 (4)°. The aldehyde O atom lies close to the plane of the fused ring as indicted by the N1—C2—C9=O10 torsion angle of 4.15 (17)°. Atom F14 lies −0.0118 (8) Å away from the best least-squares plane of the phenyl ring.

In the crystal, C—H⋯O and C—H⋯F hydrogen bonds (Table 1) link the molecules into a three-dimensional network, enclosing R₂²(14), R₃³(16), R₄⁴(18), R₄⁴(24) and R₄⁴(30) ring motifs (Fig. 2). It may be noted that the aldehyde O10 atom accepts three such bonds in a distorted tetrahedral arrangement (including the C8=O10 bond). Atom F14 accepts two hydrogen bonds in a distorted trigonal arrangement including the C14—F1 bond. Further, there is a weak π–π stacking interaction between the pyridine rings with a centroid–centroid distance of 3.9090 (7) Å. No significant C—H⋯π interactions are observed.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯O10ⁱ	0.95	2.45	3.3579 (14)	160
C12—H12⋯O10ⁱⁱ	0.95	2.45	3.3449 (15)	158
C16—H16⋯O10ⁱⁱⁱ	0.95	2.47	3.3754 (14)	159
C5—H5⋯F14^iv	0.95	2.50	3.1435 (13)	125
C9—H9⋯F14^v	0.95	2.55	3.2089 (14)	127
Symmetry codes: (i) ; (ii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) ; (iv) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (v) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Figure 2
A partial packing diagram of (I) viewed down the a-axis direction with C—H⋯O hydrogen bonds shown as dashed lines. Hydrogen atoms not involved in these interactions have been omitted for clarity.

In order to further visualize the intermolecular interactions in the crystal of (I), a Hirshfeld surface analysis (Fig. 3) was carried out using Crystal Explorer 17.5 (Spackman et al., 2021 ). The overall two-dimensional fingerprint plot, Fig. 4a, and those delineated into different contact types (McKinnon et al., 2007 ) are illustrated in Fig. 4b–l. These indicate that the most important contributions to the crystal packing are from H⋯H (30.4%), H⋯C/C⋯H (23.7%), H⋯O/O⋯H (12.2%) and H⋯F/F⋯H (11.1%) interactions.

Figure 3
View of the three-dimensional Hirshfeld surface of (I) plotted over d_norm.

Figure 4
The two-dimensional fingerprint plots for (I), showing (a) all interactions, and delineated into (b) H⋯H, (c) H⋯C/C⋯H, (d) H⋯O/O⋯H, (e) H⋯F/F⋯H, (f) H⋯N/N⋯H, (g) C⋯C, (h) F⋯C/C⋯F, (i) F⋯N/N⋯F, (j) C⋯O/O⋯C, (k) C⋯N/N⋯C and (l) N⋯O/O⋯N interactions. The d_i and d_e values are the closest internal and external distances (in Å) from given points on the Hirshfeld surface.

Synthesis and crystallization

A solution of equimolar amounts of 2-aminopyridine (2 mmol) and 2-chloro-2-(diethoxymethyl)-3-(4-fluorophenyl)oxirane (2 mmol) in 20 ml of 95% aqueous ethanol was heated at reflux for 5 h. The solvent was removed in vacuo, and the remaining white powder was recrystallized from dry acetonitrile solution to give the title compound in the form of colorless prisms. Yield: 45%, m.p. 420–421 K. Analysis calculated for C₁₄H₉FN₂O: C, 69.99; H, 3.78; N, 11.66. Found: C, 69.96; H, 3.75; N, 11.63. ¹H NMR (300 MHz, DMSO-d₆): 6.86–8.47 (8H, Ar) and 9.79 (1H, CHO). ¹³C NMR (200 MHz, DMSO-d₆): 111.89, 115.78, 116.90, 111.87, 121.32, 126.18, 130.39, 132.79, 140.89, 147.48, 160.87, 165.96, 185.45.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₄H₉FN₂O
M_r	240.23
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	8.97833 (9), 10.13609 (9), 12.85096 (15)
β (°)	110.3575 (13)
V (Å³)	1096.46 (2)
Z	4
Radiation type	Cu Kα
μ (mm⁻¹)	0.88
Crystal size (mm)	0.39 × 0.30 × 0.16

Data collection
Diffractometer	XtaLAB Synergy, Dualflex, HyPix
Absorption correction	Gaussian (CrysAlis PRO; Rigaku OD, 2023 $[Rigaku OD (2023). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England.]$ )
T_min, T_max	0.153, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	13951, 2296, 2221
R_int	0.023
(sin θ/λ)_max (Å⁻¹)	0.632

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.096, 1.07
No. of reflections	2296
No. of parameters	164
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.36, −0.17
Computer programs: CrysAlis PRO (Rigaku OD, 2023 $[Rigaku OD (2023). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England.]$ ), SHELXT2014/5 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Structural data

CCDC reference: 2465675

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S241431462500553X/hb4525sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S241431462500553X/hb4525Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S241431462500553X/hb4525Isup3.cml

checkCIF report

Computing details top

3-(4-Fluorophenyl)imidazo[1,2-a]pyridine-2-carbaldehyde top

Crystal data top

C₁₄H₉FN₂O	F(000) = 496
M_r = 240.23	D_x = 1.455 Mg m⁻³
Monoclinic, P2₁/n	Cu Kα radiation, λ = 1.54184 Å
a = 8.97833 (9) Å	Cell parameters from 10360 reflections
b = 10.13609 (9) Å	θ = 5.2–76.8°
c = 12.85096 (15) Å	µ = 0.88 mm⁻¹
β = 110.3575 (13)°	T = 100 K
V = 1096.46 (2) Å³	Prism, colorless
Z = 4	0.39 × 0.30 × 0.16 mm

Data collection top

XtaLAB Synergy, Dualflex, HyPix diffractometer	2296 independent reflections
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Cu) X-ray Source	2221 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.023
Detector resolution: 10.0000 pixels mm^-1	θ_max = 77.0°, θ_min = 5.3°
ω scans	h = −10→11
Absorption correction: gaussian (CrysAlisPro; Rigaku OD, 2023)	k = −12→12
T_min = 0.153, T_max = 1.000	l = −16→15
13951 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.036	H-atom parameters constrained
wR(F²) = 0.096	w = 1/[σ²(F_o²) + (0.0493P)² + 0.4295P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max = 0.001
2296 reflections	Δρ_max = 0.36 e Å⁻³
164 parameters	Δρ_min = −0.17 e Å⁻³
0 restraints	Extinction correction: SHELXL2018/3 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: dual	Extinction coefficient: 0.0041 (4)

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. The C-bound hydrogen atom positions were calculated geometrically (C—H = 0.95 Å) and refined using a riding model by applying the constraint of U_iso(H) = 1.2U_eq(C).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
F14	0.94015 (9)	0.74538 (7)	0.18719 (7)	0.0262 (2)
O10	0.32012 (9)	1.07889 (8)	0.39594 (7)	0.0216 (2)
N4	0.37034 (10)	0.63485 (9)	0.37344 (7)	0.0149 (2)
N1	0.24663 (11)	0.80627 (9)	0.42026 (8)	0.0175 (2)
C3	0.44194 (13)	0.74722 (10)	0.35264 (9)	0.0156 (2)
C2	0.36309 (12)	0.85016 (11)	0.38211 (8)	0.0157 (2)
C11	0.57305 (13)	0.74542 (10)	0.30875 (10)	0.0165 (2)
C8A	0.25290 (12)	0.67653 (11)	0.41485 (9)	0.0169 (2)
C12	0.55893 (13)	0.67604 (11)	0.21145 (9)	0.0188 (2)
H12	0.464190	0.628630	0.173733	0.023*
C5	0.40337 (12)	0.50308 (10)	0.36430 (9)	0.0167 (2)
H5	0.485900	0.478047	0.337956	0.020*
C15	0.83753 (13)	0.81605 (11)	0.32299 (10)	0.0209 (3)
H15	0.932676	0.863295	0.359970	0.025*
C6	0.31690 (13)	0.41015 (11)	0.39326 (9)	0.0186 (2)
H6	0.338214	0.319273	0.386936	0.022*
C16	0.71280 (13)	0.81545 (10)	0.36391 (9)	0.0186 (2)
H16	0.722589	0.862899	0.429719	0.022*
C13	0.68258 (14)	0.67605 (11)	0.16965 (9)	0.0205 (2)
H13	0.673737	0.629443	0.103622	0.025*
C14	0.81886 (14)	0.74598 (10)	0.22711 (10)	0.0198 (3)
C9	0.39053 (12)	0.99003 (11)	0.36905 (9)	0.0171 (2)
H9	0.468252	1.013253	0.337566	0.021*
C8	0.16225 (13)	0.57789 (12)	0.44436 (10)	0.0219 (3)
H8	0.080367	0.602209	0.471573	0.026*
C7	0.19366 (14)	0.44852 (12)	0.43332 (10)	0.0222 (3)
H7	0.132621	0.382589	0.452579	0.027*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
F14	0.0238 (4)	0.0262 (4)	0.0375 (4)	−0.0010 (3)	0.0220 (3)	−0.0008 (3)
O10	0.0223 (4)	0.0171 (4)	0.0256 (4)	0.0027 (3)	0.0084 (3)	−0.0022 (3)
N4	0.0147 (4)	0.0141 (5)	0.0167 (4)	−0.0005 (3)	0.0068 (3)	0.0006 (3)
N1	0.0165 (4)	0.0179 (5)	0.0199 (4)	0.0003 (3)	0.0089 (4)	−0.0002 (3)
C3	0.0153 (5)	0.0149 (5)	0.0167 (5)	−0.0009 (4)	0.0060 (4)	0.0006 (4)
C2	0.0147 (5)	0.0167 (5)	0.0161 (5)	0.0005 (4)	0.0060 (4)	−0.0003 (4)
C11	0.0165 (5)	0.0143 (5)	0.0211 (5)	0.0022 (4)	0.0094 (4)	0.0030 (4)
C8A	0.0153 (5)	0.0194 (5)	0.0177 (5)	0.0007 (4)	0.0080 (4)	0.0001 (4)
C12	0.0191 (5)	0.0167 (5)	0.0224 (5)	−0.0007 (4)	0.0095 (4)	0.0003 (4)
C5	0.0174 (5)	0.0151 (5)	0.0180 (5)	0.0017 (4)	0.0066 (4)	−0.0005 (4)
C15	0.0177 (5)	0.0172 (5)	0.0296 (6)	−0.0009 (4)	0.0104 (4)	0.0004 (4)
C6	0.0210 (5)	0.0149 (5)	0.0189 (5)	−0.0001 (4)	0.0057 (4)	0.0002 (4)
C16	0.0191 (5)	0.0154 (5)	0.0232 (5)	0.0002 (4)	0.0096 (4)	−0.0004 (4)
C13	0.0249 (6)	0.0171 (5)	0.0237 (5)	0.0004 (4)	0.0138 (5)	−0.0003 (4)
C14	0.0192 (5)	0.0172 (5)	0.0292 (6)	0.0026 (4)	0.0162 (5)	0.0043 (4)
C9	0.0163 (5)	0.0167 (5)	0.0184 (5)	0.0004 (4)	0.0061 (4)	−0.0003 (4)
C8	0.0204 (5)	0.0232 (6)	0.0269 (6)	−0.0012 (4)	0.0142 (5)	0.0009 (4)
C7	0.0226 (5)	0.0210 (6)	0.0255 (6)	−0.0045 (4)	0.0116 (4)	0.0020 (4)

Geometric parameters (Å, º) top

F14—C14	1.3556 (13)	C5—H5	0.9500
O10—C9	1.2175 (14)	C5—C6	1.3527 (15)
N4—C3	1.3790 (13)	C15—H15	0.9500
N4—C8A	1.4013 (13)	C15—C16	1.3930 (15)
N4—C5	1.3820 (13)	C15—C14	1.3810 (17)
N1—C2	1.3741 (13)	C6—H6	0.9500
N1—C8A	1.3192 (15)	C6—C7	1.4272 (15)
C3—C2	1.3855 (15)	C16—H16	0.9500
C3—C11	1.4718 (14)	C13—H13	0.9500
C2—C9	1.4587 (15)	C13—C14	1.3843 (17)
C11—C12	1.4014 (15)	C9—H9	0.9500
C11—C16	1.4006 (15)	C8—H8	0.9500
C8A—C8	1.4215 (15)	C8—C7	1.3591 (17)
C12—H12	0.9500	C7—H7	0.9500
C12—C13	1.3914 (15)

C3—N4—C8A	106.72 (9)	C14—C15—H15	121.0
C3—N4—C5	130.80 (9)	C14—C15—C16	118.08 (10)
C5—N4—C8A	122.39 (9)	C5—C6—H6	120.0
C8A—N1—C2	104.61 (9)	C5—C6—C7	120.05 (10)
N4—C3—C2	104.59 (9)	C7—C6—H6	120.0
N4—C3—C11	123.57 (9)	C11—C16—H16	119.8
C2—C3—C11	131.83 (9)	C15—C16—C11	120.49 (10)
N1—C2—C3	112.23 (10)	C15—C16—H16	119.8
N1—C2—C9	122.39 (10)	C12—C13—H13	121.0
C3—C2—C9	125.28 (10)	C14—C13—C12	118.03 (10)
C12—C11—C3	120.80 (10)	C14—C13—H13	121.0
C16—C11—C3	119.66 (10)	F14—C14—C15	118.41 (10)
C16—C11—C12	119.54 (10)	F14—C14—C13	118.24 (10)
N4—C8A—C8	117.75 (10)	C15—C14—C13	123.35 (10)
N1—C8A—N4	111.84 (9)	O10—C9—C2	124.14 (10)
N1—C8A—C8	130.41 (10)	O10—C9—H9	117.9
C11—C12—H12	119.7	C2—C9—H9	117.9
C13—C12—C11	120.52 (10)	C8A—C8—H8	120.3
C13—C12—H12	119.7	C7—C8—C8A	119.47 (10)
N4—C5—H5	120.4	C7—C8—H8	120.3
C6—C5—N4	119.27 (10)	C6—C7—H7	119.5
C6—C5—H5	120.4	C8—C7—C6	121.04 (10)
C16—C15—H15	121.0	C8—C7—H7	119.5

N4—C3—C2—N1	0.12 (12)	C11—C12—C13—C14	0.17 (16)
N4—C3—C2—C9	−176.34 (9)	C8A—N4—C3—C2	−0.30 (11)
N4—C3—C11—C12	53.26 (15)	C8A—N4—C3—C11	179.59 (10)
N4—C3—C11—C16	−127.70 (11)	C8A—N4—C5—C6	1.88 (16)
N4—C8A—C8—C7	1.04 (16)	C8A—N1—C2—C3	0.12 (12)
N4—C5—C6—C7	−0.33 (16)	C8A—N1—C2—C9	176.70 (10)
N1—C2—C9—O10	4.15 (17)	C8A—C8—C7—C6	0.41 (17)
N1—C8A—C8—C7	−178.51 (11)	C12—C11—C16—C15	−0.27 (16)
C3—N4—C8A—N1	0.41 (12)	C12—C13—C14—F14	179.47 (9)
C3—N4—C8A—C8	−179.23 (10)	C12—C13—C14—C15	−0.43 (17)
C3—N4—C5—C6	178.09 (10)	C5—N4—C3—C2	−176.96 (10)
C3—C2—C9—O10	−179.73 (10)	C5—N4—C3—C11	2.94 (18)
C3—C11—C12—C13	179.21 (10)	C5—N4—C8A—N1	177.41 (9)
C3—C11—C16—C15	−179.32 (10)	C5—N4—C8A—C8	−2.23 (15)
C2—N1—C8A—N4	−0.32 (11)	C5—C6—C7—C8	−0.80 (17)
C2—N1—C8A—C8	179.26 (11)	C16—C11—C12—C13	0.17 (16)
C2—C3—C11—C12	−126.88 (13)	C16—C15—C14—F14	−179.57 (9)
C2—C3—C11—C16	52.16 (17)	C16—C15—C14—C13	0.33 (17)
C11—C3—C2—N1	−179.76 (11)	C14—C15—C16—C11	0.03 (16)
C11—C3—C2—C9	3.8 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O10ⁱ	0.95	2.45	3.3579 (14)	160
C12—H12···O10ⁱⁱ	0.95	2.45	3.3449 (15)	158
C16—H16···O10ⁱⁱⁱ	0.95	2.47	3.3754 (14)	159
C5—H5···F14^iv	0.95	2.50	3.1435 (13)	125
C9—H9···F14^v	0.95	2.55	3.2089 (14)	127

Symmetry codes: (i) x, y−1, z; (ii) −x+1/2, y−1/2, −z+1/2; (iii) −x+1, −y+2, −z+1; (iv) −x+3/2, y−1/2, −z+1/2; (v) −x+3/2, y+1/2, −z+1/2.

Acknowledgements

The crystal structure determination was performed in the Department of Structural Studies of the Zelinsky Institute of Organic Chemistry, Moscow. This work was supported by the Azerbaijan Technological Ubniversity, King Abdulaziz University (Saudi Arabia), Azerbaijan Medical University and Baku Engineering University. TH is also grateful to Hacettepe University Scientific Research Project Unit (grant No. 013 D04 602 004). The authors' contributions are as follows. Conceptualizations, FIG, TH and ANB; synthesis, FIG and SZH; X-ray analysis, AIS; Hirshfeld surface analyses, crystal voids, intermolecular interaction energies and energy frameworks, TH; writing (review and editing of the manuscript), TH, JL and KIH; funding acquisition, KIH and NAG; supervision, TH and ANB.

References

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