Synthesis, crystal structure and Hirshfeld surface analysis of N-(6-acetyl-1-nitro­naphthalen-2-yl)acetamide

Shi, X.-W.; Zheng, S.-J.; Lu, Q.-Q.; Li, G.; Zhou, Y.F.

doi:10.1107/S2056989024001609

research communications

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 80| Part 4| April 2024| Pages 347-350

https://doi.org/10.1107/S2056989024001609

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Synthesis, crystal structure and Hirshfeld surface analysis of N-(6-acetyl-1-nitronaphthalen-2-yl)acetamide

Xin-Wei Shi,^a Shao-Jun Zheng,^b Qiang-Qiang Lu,^a Gen Li ^a and Ya-Fu Zhou ^a ^*

^aXi'an Botanical Garden of Shaanxi Province (Institute of Botany of Shaanxi Province), Shaanxi Engineering Research Centre for Conservation and Utilization of Botanical Resources, Xi'an 710061, People's Republic of China, and ^bSchool of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu, People's Republic of China
^*Correspondence e-mail: yafu-zhou@xab.ac.cn

Edited by A. Briceno, Venezuelan Institute of Scientific Research, Venezuela (Received 20 November 2023; accepted 18 February 2024; online 6 March 2024)

The title compound, C₁₄H₁₂N₂O₄, was obtained from 2-acetyl-6-aminonaphthalene through two-step reactions of acetylation and nitration. The molecule comprises the naphthalene ring system consisting of functional systems bearing a acetyl group (C-2), a nitro group (C-5), and an acetylamino group (C-6). In the crystal, the molecules are assembled into two-dimensional sheet-like structures by intermolecular N—H⋯O and C—H⋯O hydrogen-bonding interactions. Hirshfeld surface analysis illustrates that the most important contributions to the crystal packing are from O⋯H/H⋯O (43.7%), H⋯H (31.0%), and C⋯H/H⋯C (8.5%) contacts.

Keywords: crystal structure; naphthalene ring; hydrogen bonding; Hirshfeld surface analysis.

CCDC reference: 2333518

1. Chemical context

Organic small molecules with naphthalene ring systems are attractive photonic materials due to their high photoluminescence quantum efficiency, color tunability, and size-dependent optical properties (Wang et al., 2012 ; Yao et al., 2013 ). Modifying the organic molecular structure can tune the intermolecular hydrogen-bonding and π–π stacking interactions, which influence their packing mode during self-assembly and determine the final aggregated structures. The molecular stacking patterns in crystals can affect asymmetric light propagation (Yagai et al., 2012 ; Zou et al., 2018 ; Zhang et al., 2018 ).

The title compound (I), N-(6-acetyl-1-nitronaphthalen-2-yl)acetamide, obtained from 2-acetyl-6-aminonaphthalene through two-step reactions of acetylation and nitration, is a Prodane fluorescent dye with red fluorescence and a large Stoke shift (Xu et al., 2017 ). The stacking of naphthalene compounds into crystals depends on intermolecular hydrogen bonds and π–π stacking interactions. The nitro group and the acetylamino group of the naphthalene ring system will affect intermolecular interactions, making it possible to change the one- or two-dimensional stacking arrangement, which in turn affects photo-ion conduction (Eya'ane Meva et al., 2012 ; Nguyen et al., 2004 ).

2. Structural commentary

The molecular structure of the title compound (I) is shown in Fig. 1. The molecules are semi-rigid and almost fully coplanar, except for the nitro oxygen atoms and methyl hydrogen atoms. Notably, compound (I) has a primary amine group on the naphthalene core, while the reactant has a secondary amine at the same position. It may have more steric repulsion with neighboring molecules compared to the reactant when assembled into 2D structures. Self-assembly of naphthalene framework organic molecules through π–π stacking forms 3D sheet-like structures with uniform dimensions.

Figure 1
The molecular structure of the title compound (I)

with the atomic numbering scheme. Displacement ellipsoids are depicted at the 50% probability level.

In compound (I), the nitro group and acetylamino group are adjacent, located at positions C-5 and C-6, respectively, and the acetyl group is located at the 2-position of the naphthalene ring system. The angle between the two oxygen atoms on the nitro group located at positions C-5 is 123.93 (18)°, and the torsion angles C6—C5—N1—O3 and C10—C5—N1—O3 are −90.34 (15) and 89.66 (15)°, respectively. The angles of the acetyl group at the 2-position, O1—C11—C2 and O1—C11—C12, are 120.13 (18) and 120.52 (18)°, respectively. In addition, the dihedral angle between the nitro group and the plane through the naphthalene ring system is 89.66 (15)°.

3. Supramolecular features

In the crystal, a unit cell contains four molecules, which exhibit a centrosymmetric arrangement (Fig. 2), and hydrogen bonding and π–π stacking interactions were responsible for the formation of the crystal structures with distinct morphologies.

Figure 2
The packing of molecules in the title compound (I)

, viewed along the b-axis direction (N2—H2⋯O1 hydrogen bonds are shown as orange dashed lines, C7—H7⋯O2 and C4—H4⋯O2 hydrogen bonds are shown as gray dashed lines).

The growth pattern for the title compound (I) is a 1D wire-like structure and hydrogen bonding advances the growth along the a-axis direction. The molecules are linked via N2—H2⋯O1 hydrogen bonds, generating 2D layers propagating along the [010] axis direction (Table 1). Without hydrogen-bonding and other strong interactions between molecules in adjacent layers, π–π stacking interactions, with centroid–centroid distcances of 3.67 Å, are the predominant driving force during self-assembly, which facilitates the crystal of the title compound growth along the [010] direction, forming a 3D structure (Meva et al., 2012; Nguyen et al., 2004). Weak C4—H4⋯O2 contacts are also observed.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O1ⁱ	0.86	2.35	3.177 (2)	161
C7—H7⋯O2	0.93	2.18	2.792 (2)	123
C4—H4⋯O2ⁱⁱ	0.93	2.34	3.219 (2)	157
Symmetry codes: (i) ; (ii) .

4. Hirshfeld Surface analysis

A Hirshfeld surface analysis was performed and the associated fingerprint plots, which provide a 2D view of the intermolecular interactions within molecular crystals, were generated using Crystal Explorer 21.5 (Spackman et al., 2021 ), with a standard resolution of the 3D d_norm surfaces plotted over a fixed color scale of −0.1253 (red) to 1.4046 (blue) arbitrary units (Fig. 3). The N2—H2⋯O1 hydrogen bond was identified to be a crucial structure-forming interaction within the crystal packing. The intense red spots symbolizing short contacts and negative d_norm values on the surface are related to the presence of the N2—H2⋯O1 hydrogen bonds in the crystal structure. The weak C4—H4⋯O2 contacts are indicated by faint red spots (Fig. 4).

Figure 3
Front view of the three-dimensional Hirshfeld surface of the title compound (I)

mapped over d_norm.

Figure 4
Hirshfeld surface mapped over d_norm for the title compound (I)

showing: H⋯O/O⋯H (upside and downside) contacts.

The 2D fingerprint plots for the H⋯O/O⋯H, H⋯H, H⋯C/C⋯H, and H⋯N/N⋯H contacts are shown in Fig. 5. The most significant interactions are H⋯O/O⋯H, which play a defining role in the overall crystal packing, contributing 43.7%, and are located in the tip and middle region of the fingerprint plot. H⋯H interactions contribute 31.0%, being located in the middle region of the fingerprint plot. The contributions of the weak H⋯C/C⋯H and H⋯N/N⋯H contacts to the Hirshfeld surface are 8.5 and 1.1%, respectively.

Figure 5
The two-dimensional fingerprint plots of the title compound (I)

, showing (a) all interactions, and delineated into (b) H⋯H, (c) O⋯H/H⋯O, (d) C⋯H/H⋯C, and (e) N⋯H/H⋯N interactions [The d_e and d_i values represent the distances (in Å) from a point on the Hirshfeld surface to the nearest atoms inside and outside the surface, respectively.]

Shape-index and curvedness are the metrics that describe the local shape in terms of principal curvatures, representing the surface properties of the crystal molecule to determine their arrangements. The Hirshfeld surface mapped over electrostatic potential, shape-index, curvedness and fragment patches is shown in Fig. 6. The electrostatic potential map (Fig. 6a) highlights the electronegative (red) and electropositive (blue) regions in the molecule. The molecule shows red colored regions near the oxygen atom (O1), indicating the electronegative spots (Akhileshwari et al., 2021 ). The pattern of red and blue triangles on the shape-index map (Fig. 6b) shows feature characteristic of π–π interactions. As the molecule shows flat regions on the curvedness map (Fig. 6c), it is evident that the title molecule is arranged in planar stacking (Spackman & Jayatilaka, 2009 ). The fragment patches (Fig. 6d) illustrates the coordination number of the corresponding atoms in the compound.

Figure 6
Hirshfeld surface of the title compound (I)

mapped over (a) electrostatic potential, (b) shape-index, (c) curvedness, and (d) fragment patches.

5. Synthesis and crystallization

1.0 g of 2-acetyl-6-aminonaphthalene were dissolved in 35 ml of Ac₂O, stirred for 10 minutes, and 30 ml of CH₃COOH were added, followed by the slow addition of 6.5 ml of concentrated HNO₃ under ice-bath conditions for 3 h at room temperature. When the reaction was complete, it is extracted with CH₂Cl₂ three times, the organic phase was combined, the positive silica gel column was passed under normal pressure after spinning (eluent CH₂Cl₂:ethyl acetate, 10:1). The eluent containing the product components was collected and the light-yellow solid was concentrated. It was dissolved in methanol and placed in a refrigerator at 277 to cultivate light-yellow transparent square crystals (Xu et al., 2017). The MeOH was dissolved and red transparent square crystals suitable for X-ray diffraction were were obtained at 277 K in the refrigerator.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms were positioned geometrically (C—H = 0.93–0.95 Å) and allowed to ride on their parent atoms, with U_iso(H) =1.2 U_eq(C) or 1.5U_eq(C-methyl).

Table 2
Experimental details

Crystal data
Chemical formula	C₁₄H₁₂N₂O₄
M_r	272.26
Crystal system, space group	Monoclinic, P2₁/m
Temperature (K)	293
a, b, c (Å)	8.7649 (14), 6.8899 (11), 10.6868 (18)
β (°)	104.676 (4)
V (Å³)	624.31 (18)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.11
Crystal size (mm)	0.22 × 0.20 × 0.18

Data collection
Diffractometer	Bruker CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
No. of measured, independent and observed [I > 2σ(I)] reflections	4087, 1229, 1079
R_int	0.016
(sin θ/λ)_max (Å⁻¹)	0.599

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.043, 0.124, 1.07
No. of reflections	1229
No. of parameters	118
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.21, −0.29
Computer programs: SMART and SAINT (Bruker, 2002 ), SHELXT2014/7 (Sheldrick, 2015a ), SHELXL2014/7 (Sheldrick, 2015b ), SHELXTL (Sheldrick, 2008 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 2333518

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989024001609/zn2035sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989024001609/zn2035Isup3.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989024001609/zn2035Isup3.cml

checkCIF report

Computing details top

N-(6-Acetyl-1-nitronaphthalen-2-yl)acetamide top

Crystal data top

C₁₄H₁₂N₂O₄	F(000) = 284
M_r = 272.26	D_x = 1.448 Mg m⁻³
Monoclinic, P2₁/m	Mo Kα radiation, λ = 0.71073 Å
a = 8.7649 (14) Å	Cell parameters from 1846 reflections
b = 6.8899 (11) Å	θ = 2.4–25.0°
c = 10.6868 (18) Å	µ = 0.11 mm⁻¹
β = 104.676 (4)°	T = 293 K
V = 624.31 (18) Å³	Block, red
Z = 2	0.22 × 0.20 × 0.18 mm

Data collection top

Bruker CCD diffractometer	1079 reflections with I > 2σ(I)
phi and ω scans	R_int = 0.016
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θ_max = 25.2°, θ_min = 2.0°
	h = −9→10
4087 measured reflections	k = −8→7
1229 independent reflections	l = −12→12

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.043	H-atom parameters constrained
wR(F²) = 0.124	w = 1/[σ²(F_o²) + (0.0709P)² + 0.1248P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max < 0.001
1229 reflections	Δρ_max = 0.21 e Å⁻³
118 parameters	Δρ_min = −0.29 e Å⁻³

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.

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

	x	y	z	U_iso*/U_eq
C1	0.0705 (2)	0.7500	−0.18378 (17)	0.0351 (4)
H1	−0.0097	0.7500	−0.2598	0.042*
C2	0.2243 (2)	0.7500	−0.19094 (18)	0.0376 (5)
C3	0.3449 (2)	0.7500	−0.07463 (19)	0.0438 (5)
H3	0.4497	0.7500	−0.0786	0.053*
C4	0.3117 (2)	0.7500	0.04290 (19)	0.0416 (5)
H4	0.3934	0.7500	0.1179	0.050*
C5	0.1084 (2)	0.7500	0.16916 (16)	0.0319 (4)
C6	−0.0450 (2)	0.7500	0.17851 (17)	0.0323 (4)
C7	−0.1648 (2)	0.7500	0.06065 (18)	0.0384 (5)
H7	−0.2703	0.7500	0.0626	0.046*
C8	−0.1267 (2)	0.7500	−0.05469 (18)	0.0378 (5)
H8	−0.2076	0.7500	−0.1303	0.045*
C9	0.0307 (2)	0.7500	−0.06439 (17)	0.0321 (4)
C10	0.1533 (2)	0.7500	0.05139 (17)	0.0320 (4)
C11	0.2589 (2)	0.7500	−0.32103 (19)	0.0423 (5)
C12	0.4260 (3)	0.7500	−0.3295 (2)	0.0620 (7)
H12A	0.4321	0.7500	−0.4154	0.074*
H12B	0.4769	0.6362	−0.2882	0.074*
C13	−0.2245 (2)	0.7500	0.3252 (2)	0.0440 (5)
C14	−0.2240 (3)	0.7500	0.4642 (2)	0.0561 (6)
H14A	−0.3152	0.7500	0.4775	0.067*
H14B	−0.1689	0.8561	0.5077	0.067*
N1	0.23711 (18)	0.7500	0.28778 (14)	0.0398 (4)
N2	−0.07930 (18)	0.7500	0.29967 (15)	0.0389 (4)
H2	0.0005	0.7500	0.3659	0.047*
O1	0.15177 (18)	0.7500	−0.41834 (14)	0.0603 (5)
O2	−0.34453 (19)	0.7500	0.24224 (16)	0.0925 (8)
O3	0.28721 (15)	0.5958 (2)	0.33316 (11)	0.0761 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0347 (10)	0.0390 (10)	0.0289 (9)	0.000	0.0032 (7)	0.000
C2	0.0365 (10)	0.0409 (10)	0.0359 (10)	0.000	0.0099 (8)	0.000
C3	0.0297 (9)	0.0613 (13)	0.0407 (11)	0.000	0.0091 (8)	0.000
C4	0.0291 (9)	0.0583 (13)	0.0340 (10)	0.000	0.0020 (7)	0.000
C5	0.0314 (9)	0.0328 (9)	0.0292 (9)	0.000	0.0032 (7)	0.000
C6	0.0333 (9)	0.0313 (9)	0.0321 (9)	0.000	0.0079 (7)	0.000
C7	0.0284 (9)	0.0498 (11)	0.0363 (10)	0.000	0.0070 (8)	0.000
C8	0.0296 (9)	0.0474 (11)	0.0324 (10)	0.000	0.0009 (7)	0.000
C9	0.0318 (9)	0.0313 (9)	0.0316 (10)	0.000	0.0052 (7)	0.000
C10	0.0309 (9)	0.0319 (9)	0.0315 (9)	0.000	0.0049 (7)	0.000
C11	0.0427 (11)	0.0474 (12)	0.0386 (11)	0.000	0.0135 (9)	0.000
C12	0.0453 (12)	0.100 (2)	0.0449 (12)	0.000	0.0190 (10)	0.000
C13	0.0358 (10)	0.0567 (13)	0.0410 (11)	0.000	0.0124 (9)	0.000
C14	0.0490 (12)	0.0812 (17)	0.0417 (12)	0.000	0.0182 (10)	0.000
N1	0.0329 (8)	0.0573 (11)	0.0288 (8)	0.000	0.0068 (7)	0.000
N2	0.0319 (8)	0.0539 (10)	0.0301 (8)	0.000	0.0062 (6)	0.000
O1	0.0463 (9)	0.1019 (14)	0.0327 (8)	0.000	0.0100 (7)	0.000
O2	0.0324 (8)	0.201 (3)	0.0432 (9)	0.000	0.0078 (7)	0.000
O3	0.0803 (9)	0.0778 (9)	0.0545 (7)	0.0232 (7)	−0.0123 (6)	0.0131 (6)

Geometric parameters (Å, º) top

C1—C2	1.370 (3)	C8—C9	1.410 (3)
C1—C9	1.405 (3)	C8—H8	0.9300
C1—H1	0.9300	C9—C10	1.418 (2)
C2—C3	1.413 (3)	C11—O1	1.212 (2)
C2—C11	1.496 (3)	C11—C12	1.490 (3)
C3—C4	1.359 (3)	C12—H12A	0.9328
C3—H3	0.9300	C12—H12B	0.9534
C4—C10	1.414 (3)	C13—O2	1.192 (3)
C4—H4	0.9300	C13—N2	1.367 (2)
C5—C6	1.374 (3)	C13—C14	1.484 (3)
C5—C10	1.410 (3)	C14—H14A	0.8470
C5—N1	1.468 (2)	C14—H14B	0.9329
C6—N2	1.402 (2)	N1—O3	1.2038 (14)
C6—C7	1.421 (3)	N1—O3ⁱ	1.2038 (14)
C7—C8	1.356 (3)	N2—H2	0.8600
C7—H7	0.9300

C2—C1—C9	121.65 (17)	C1—C9—C8	122.63 (17)
C2—C1—H1	119.2	C1—C9—C10	119.02 (17)
C9—C1—H1	119.2	C8—C9—C10	118.35 (17)
C1—C2—C3	118.58 (17)	C5—C10—C4	123.87 (17)
C1—C2—C11	119.07 (18)	C5—C10—C9	117.26 (16)
C3—C2—C11	122.34 (17)	C4—C10—C9	118.87 (17)
C4—C3—C2	121.69 (18)	O1—C11—C12	120.52 (18)
C4—C3—H3	119.2	O1—C11—C2	120.13 (18)
C2—C3—H3	119.2	C12—C11—C2	119.35 (18)
C3—C4—C10	120.19 (17)	C11—C12—H12A	111.2
C3—C4—H4	119.9	C11—C12—H12B	108.9
C10—C4—H4	119.9	H12A—C12—H12B	108.6
C6—C5—C10	124.35 (16)	O2—C13—N2	122.84 (19)
C6—C5—N1	119.30 (16)	O2—C13—C14	121.53 (19)
C10—C5—N1	116.35 (15)	N2—C13—C14	115.63 (17)
C5—C6—N2	120.69 (16)	C13—C14—H14A	113.9
C5—C6—C7	116.93 (16)	C13—C14—H14B	111.7
N2—C6—C7	122.38 (16)	H14A—C14—H14B	107.9
C8—C7—C6	120.58 (17)	O3—N1—O3ⁱ	123.93 (18)
C8—C7—H7	119.7	O3—N1—C5	118.03 (9)
C6—C7—H7	119.7	O3ⁱ—N1—C5	118.03 (9)
C7—C8—C9	122.54 (17)	C13—N2—C6	127.79 (16)
C7—C8—H8	118.7	C13—N2—H2	116.1
C9—C8—H8	118.7	C6—N2—H2	116.1

C9—C1—C2—C3	0.000 (1)	N1—C5—C10—C9	180.000 (1)
C9—C1—C2—C11	180.000 (1)	C3—C4—C10—C5	180.000 (1)
C1—C2—C3—C4	0.000 (1)	C3—C4—C10—C9	0.0
C11—C2—C3—C4	180.000 (1)	C1—C9—C10—C5	180.000 (1)
C2—C3—C4—C10	0.000 (1)	C8—C9—C10—C5	0.0
C10—C5—C6—N2	180.000 (1)	C1—C9—C10—C4	0.000 (1)
N1—C5—C6—N2	0.000 (1)	C8—C9—C10—C4	180.0
C10—C5—C6—C7	0.000 (1)	C1—C2—C11—O1	0.000 (1)
N1—C5—C6—C7	180.000 (1)	C3—C2—C11—O1	180.000 (1)
C5—C6—C7—C8	0.000 (1)	C1—C2—C11—C12	180.000 (1)
N2—C6—C7—C8	180.000 (1)	C3—C2—C11—C12	0.000 (1)
C6—C7—C8—C9	0.000 (1)	C6—C5—N1—O3	90.34 (15)
C2—C1—C9—C8	180.000 (1)	C10—C5—N1—O3	−89.66 (15)
C2—C1—C9—C10	0.000 (1)	C6—C5—N1—O3ⁱ	−90.34 (15)
C7—C8—C9—C1	180.000 (1)	C10—C5—N1—O3ⁱ	89.66 (15)
C7—C8—C9—C10	0.000 (1)	O2—C13—N2—C6	0.000 (1)
C6—C5—C10—C4	180.000 (1)	C14—C13—N2—C6	180.000 (1)
N1—C5—C10—C4	0.000 (1)	C5—C6—N2—C13	180.000 (1)
C6—C5—C10—C9	0.000 (1)	C7—C6—N2—C13	0.000 (1)

Symmetry code: (i) x, −y+3/2, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O1ⁱⁱ	0.86	2.35	3.177 (2)	161
C7—H7···O2	0.93	2.18	2.792 (2)	123
C4—H4···O2ⁱⁱⁱ	0.93	2.34	3.219 (2)	157

Symmetry codes: (ii) x, y, z+1; (iii) x+1, y, z.

Acknowledgements

The authors thank Hubei Normal University and Nian Zhao for recording the X-ray crystallographic data for the crystals.

Funding information

Funding for this research was provided by: the Xi'an Science and Technology Plan Project (grant No. 20NYYF0043); the Key Research and Development Program of Shaanxi (grant No. 2023-YBNY-248 and 2023-YBNY-100); the Key Research and Development Program of China (grant No. 2021YFD1600400); the National Natural Science Foundation of China (grant No. 42301053).

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