(E)-N,N-Diethyl-4-{[(4-meth­oxy­phen­yl)imino]­meth­yl}aniline: crystal structure, Hirshfeld surface analysis and energy framework

Subashini, A.; Kumaravel, R.; Tharmalingam, B.; Ramamurthi, K.; Crochet, A.; Stoeckli-Evans, H.

doi:10.1107/S2056989024000574

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 80| Part 2| February 2024| Pages 201-206

https://doi.org/10.1107/S2056989024000574

Open

access

(E)-N,N-Diethyl-4-{[(4-methoxyphenyl)imino]methyl}aniline: crystal structure, Hirshfeld surface analysis and energy framework

A. Subashini,^a ^* R. Kumaravel,^b B. Tharmalingam,^c K. Ramamurthi,^d Aurélien Crochet ^e and Helen Stoeckli-Evans ^f ^*

^aPG and Research Department of Physics, Srimad Andavan Arts and Science College (Autonomous), Affiliated to Bharathidasan University, Tiruchirappalli 620005, Tamilnadu, India, ^bDepartment of Physics, Annapoorana Engineering College (Autonomous), Salem 636308, Tamilnadu, India, ^cDepartment of Chemistry, Bharathiyar University, Coimbatore 600 046, Tamilnadu, India, ^dCrystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamilnadu, India, ^eChemistry Department, University of Fribourg, Chemin du Musee 9, CH-1700 Fribourg, Switzerland, and ^fInstitute of Physics, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
^*Correspondence e-mail: viji.suba@gmail.com, helen.stoeckli-evans@unine.ch

Edited by W. T. A. Harrison, University of Aberdeen, United Kingdom (Received 3 January 2024; accepted 16 January 2024; online 26 January 2024)

In the title benzylideneaniline Schiff base, C₁₈H₂₂N₂O, the aromatic rings are inclined to each other by 46.01 (6)°, while the C_ar—N= C—C_ar torsion angle is 176.9 (1)°. In the crystal, the only identifiable directional interaction is a weak C—H⋯π hydrogen bond, which generates inversion dimers that stack along the a-axis direction.

Keywords: crystal structure; benzylideneaniline; Schiff base; Hirshfeld surface analysis; energy framework.

CCDC reference: 2325829

1. Chemical context

Schiff bases are known for their distinctive azomethine group (–N=CH–) and ease of synthesis, often by a simple condensation reaction. Brodowska & Łodyga-Chruścińska (2014 , and references therein) have reviewed Schiff bases, covering their biological, antibacterial, antitfungal, biocidal, antimalarial and anticancer activities, together with their uses in technology, synthesis and chemical analysis. The –N=CH– group plays an important role in forming stable metal complexes (Iqbal et al., 1995 ), and recently Boulechfar et al. (2023 ) have reviewed the history, synthesis and applications of Schiff bases and their metal complexes.

In the solid state, benzylideneanilines adopt a nonplanar conformation, disrupting the π-electron conjugation within the molecule (Bürgi & Dunitz, 1970 ). Beyond their chemical properties, benzylideneanilines find practical uses in various applications, such as plaque imaging, as anti-inflammatory agents, and in opto-electronic devices (Lee et al., 2009 ; Weszka et al., 2008 ; Rodrigues et al., 2003 ), and as antioxidants (Sunil et al., 2021 ).

Herein, we describe the synthesis and crystal structure of the title benzylideneaniline Schiff base (E)-N,N-diethyl-4-{[(4-methoxyphenyl)imino]methyl}aniline (I) and compare its structure and Hirshfeld surface to those of related compounds.

2. Structural commentary

The title compound crystallizes in the triclinic space group P $[\overline{1}]$ with one molecule in the asymmetric unit (Fig. 1). The aromatic rings (A = C1–C6 and B = C8–C13) are inclined to each other by 46.01 (6)°, while the C4—N1—C7—C8 torsion angle is 176.9 (1)°. The configuration about the N1=C7 bond is E and its bond length is 1.2754 (15) Å. The major twist in the molecule occurs about the C4—N1 bond, as indicated by the C5—C4—N1—C7 torsion angle of −41.89 (16)°. Atom C14 of the methoxy group lies almost in the plane of its attached ring [deviation = −0.012 (1) Å]. The N2/C15/C17 moiety is twisted by 12.85 (12)° from its attached ring and the C atom of the C16 methyl group is displaced from the C8–C13 ring by 1.329 (2) Å and C18 is displaced in the opposite sense, by −0.893 (2) Å, which we term a trans arrangement (see Database survey section).

Figure 1
A view of the molecular structure of I, with the atom labelling. The displacement ellipsoids are drawn at the 50% probability level.

3. Supramolecular features

In the crystal of I, the shortest contact involves a pair of very weak C—H⋯π interactions (Table 1). They link inversion-related molecules to form dimers that stack along the a-axis direction (Fig. 2).

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C1–C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C13—H13⋯Cg1ⁱ	0.94	2.98	3.659 (1)	130
Symmetry code: (i) .

Figure 2
A view along the b axis of the crystal packing of I. The C—H⋯π interactions are indicated by blue arrows (see Table 1

). Only the H atoms involved in these interactions have been included.

4. Database survey

A search of the Cambridge Structural Database (CSD, Version 5.44, last update September 2023; Groom et al., 2016 ) revealed the presence of two benzylideneaniline Schiff bases similar to I, namely, (E)-4-{[(4-methoxyphenyl)imino]methyl}-N,N-dimethylaniline (II) (CSD refcode SOLRIV; Sundararaman et al., 2009 ) and (E)-4-{[(4-ethoxyphenyl)imino]methyl}-N,N-dimethylaniline (III) (SITFIL; Wang & Wang, 2008 ).

Compound (II) crystallizes in the space group P2₁/n with two independent molecules in the asymmetric unit. Here, the dihedral angles A/B and A′/B′ are significantly different to each other and to that in compound I, viz. 8.20 (5) and 12.52 (6)°, compared to 46.01 (6)° in I. The N=C bond lengths are 1.2758 (15) and 1.2731 (16) Å, similar to the value observed for I. The C_ar—N=C—C_ar torsion angles are −177.6 (1) and −179.3 (1)°, compared to 176.9 (1)° in I. In III, the aromatic rings are inclined to each other by 61.94 (15)°, while the torsion angle C_ar—N=C—C_ar is 179.3 (3)° and its bond length is 1.269 (4) Å.

A full search of the CSD for p-substituted benzylideneanilines gave 229 hits for entries that fitted the following criteria: three-dimensional coordinates available, R ≤ 0.075, no disorder, no errors, no polymers, no ions, organics only and only single crystal analyses. An analysis using Mercury (Macrae et al., 2020 ) of the dihedral angle A/B indicated that it can vary from 0.9° for (E)-4-{4-[(4-chlorobenzylidene)amino]benzyl}oxazolidin-2-one (FORYIX; Kumari et al., 2019 ) to 73.4° for 4-[(E)-({4-[(4-aminophenyl)sulfonyl]phenyl}imino)methyl]phenol ethanol solvate (PAWMUX; Afzal et al., 2012 ). There are two small clusters grouped around ca 6.3 and 51.6°. Compound II fits into the first cluster, whereas compounds I and III clearly fit into the second cluster.

The analysis of the N=C bond length indicates that it varies from 1.216 Å for 4-{[4-(di-p-tolylamino)benzylidene]amino}benzonitrile (JIDRAT; Sun et al., 2023 ) to 1.315 Å for (E)-4-[4-(diethylamino)benzylideneammonio]benzenesulfonate (XAYSOH; Ruanwas et al., 2012 ), with a mean value of 1.269 Å [mean deviation of 0.013 Å, skewness −0.162; Mercury (Macrae et al., 2020)]. The C=N bond lengths in I, II and III all fall within the limits indicated from the analysis in Mercury.

Another structural feature of compound I is the arrangement of the ethyl groups of the –N(C₂H₅)₂ moiety. Here, they have a trans arrangement with one CH₃ group directed above the plane of the –CH₂—N—CH₂– unit and the other below (Fig. 1). A search of the CSD for benzylideneanilines with an N,N-diethylaniline group gave 12 hits. In nine of these structures the arrangement of this group was the same as that of compound I, but for three hits an alternative arrangement was found, viz. a cis arrangement with both CH₃ groups directed to the same side of the plane of the –CH₂—N—CH₂– unit. For example, in 4-chloro-N-[4-(diethylamino)benzylidene]aniline (DUNNAC; Zhang, 2010 ), which crystallizes with two independent molecules in the asymmetric unit, both molecules have the cis arrangement [Fig. S1(a) of the supporting information]. In the 4-bromo derivative, 4-bromo-N-[4-(diethylamino)benzylidene]aniline (SABPOC; Li, 2010 ), which also crystallizes with two independent molecules in the asymmetric unit, both arrangements are observed; i.e. one trans and the other cis [Fig. S1(b) of the supporting information]. For 4-{[4-(diethylamino)benzylidene]amino}benzoic acid, two triclinic polymorphs have been reported, with both structures having two independent molecules in the asymmetric unit. In the first (PUSMUN; Han et al., 2016 ), both molecules have a cis arrangement, while in the second polymorph (PUSMUN01; Xochicale-Santana et al., 2021 ), both molecules have a trans arrangement.

A more extensive search for diethylaminobenzene derivatives gave over 300 hits for structures with the same search criteria as above. An analysis of the two CH₃—CH₂—N—CH₂ torsion angles is shown in a scatter plot (Fig. 3). It can be seen that the majority of compounds have either the cis (−/+ or +/−) or the trans (+/+ or −/−) arrangement. Some of the outliers indicate an intermediate state with one large torsion angle and the other quite small, for example, (2-diethylaminophenyl)diphenylmethanol (ERONDO; Al-Masri et al., 2004 ), whose structure is illustrated in Fig. 3. Finally, in one compound, viz. N,N,N′,N′-tetraethyl-2,6-bis(phenylethynyl)thieno[2,3-f][1]benzothiophene-4,8-diamine (JOQZIA; Wen et al., 2015 ), a unique arrangement was observed with both ethyl groups having an extended conformation (see Fig. 3).

Figure 3
Scatter plot of the CH₂—N—CH₂—CH₃ torsion angles in diethylaminobenzene derivatives, and the structures of N,N,N′,N′-tetraethyl-2,6-bis(phenylethynyl)thieno[2,3-f][1]benzothiophene-4,8-diamine (JOQZIA; Wen et al., 2015

) and 2-diethylaminophenyl)diphenylmethanol (ERONDO; Al-Masri et al., 2004

5. Hirshfeld surface analysis and two-dimensional fingerprint plots

The Hirshfeld surface (HS) analyses and the associated two-dimensional fingerprint plots were performed with CrystalExplorer17 (Spackman et al., 2021 ) following the protocol of Tan et al. (2019 ). The Hirshfeld surfaces for compounds I, II and III are compared in Fig. 4. The absence of promient red spots indicate that short contacts are not particularly significant in the packing of the three compounds. The short contacts in the crystals of the three compounds are compared in Table S1 of the supporting information. It is not surprising that for II, with a total of seven C—H⋯π interactions in the crystal (Sundararaman et al., 2009), that there are a large number of C⋯H contacts.

Figure 4
The Hirshfeld surfaces of compounds (a) I, (b) II and (c) III, mapped over d_norm in the colour ranges of 0.00 to 1.41, −0.08 to 1.26 and −0.02 to 1.22 a.u., respectively.

The full two-dimensional fingerprint plots for I, II and III are given in Fig. 5. The contributions of the various interatomic contacts to the Hirshfeld surfaces for the three compounds are compared in Table 2. In all three compounds, the H⋯H contacts have a major contribution, i.e. 62.5% for I, 58.1% for the two independent molecule of II and 59.5% for III. The second most significant contributions are from the C⋯H/H⋯C contacts, 26.6, 29.4 and 29.8%, respectively, reflecting the presence of C—H⋯π interactions present in all three crystal structures. The other interatomic contacts, such as the N⋯H/H⋯N contacts, contribute from 5.1 to 6.3%, and the O⋯H/H⋯O contacts contribute from 4.6 to 6.0%. The C⋯C or O⋯O contacts contribute less than 1%.

Table 2
Relative percentage contributions of close contacts to the Hirshfeld surfaces of compounds I, II and III

IIa and IIb refer to the two independent molecules of compound II.

Contact	I	II	IIa	IIb	III
H⋯H	62.5	58.1	53.9	55.2	59.5
C⋯H/H⋯C	26.6	29.4	34.3	32.0	29.8
N⋯H/H⋯N	5.1	6.3	5.6	6.5	5.9
O⋯H/H⋯O	5.4	6.0	6.0	6.2	4.6

Figure 5
The full two-dimensional fingerprint plots for compounds (a) I, (b) II and (c) III, and those delineated into H⋯H, C⋯H/H⋯C, N⋯H/H⋯N and O⋯H/H⋯O contacts.

6. Energy frameworks

A comparison of the energy frameworks calculated for I, showing the electrostatic potential forces (E_ele), the dispersion forces (E_dis) and the total energy diagrams (E_tot), are shown in Fig. 6. Those for compounds II and III are given, respectively, in Figs. S3 and S4 of the supporting information. The energies were obtained by using wave functions at the HF/3-2IG level of theory. The cylindrical radii are proportional to the relative strength of the corresponding energies (Spackman et al., 2021; Tan et al., 2019). They have been adjusted to the same scale factor of 90 with a cut-off value of 6 kJ mol⁻¹ within a radius of 3.8 Å of a central reference molecule.

Figure 6
The energy frameworks calculated for I, viewed along the b-axis direction, showing the electrostatic potential forces (E_ele), the dispersion forces (E_dis) and the total energy diagrams (E_tot).

For all three compounds, the major contribution to the intermolecular interactions is from dispersion forces (E_dis), reflecting the absence of C—H⋯O or C—H⋯N hydrogen bonds in the crystals. The colour-coded interaction mappings within a radius of 3.8 Å of a central reference molecule and the various contributions to the total energy (E_tot) for compounds I, II and III are given in Figs. S5, S6 and S7, respectively, of the supporting information.

7. Synthesis and crystallization

Compound I was synthesized by condensing p-diethylaminobenzaldehyde and p-methoxyaniline (1:1) dissolved in methanol. The reaction mixture was heated under reflux for 6 h at ∼363 K and then cooled to room temperature. The precipitated product was dissolved in methanol. Yellow prismatic single crystals of I were obtained by slow evaporation of the solvent at room temperature over a period of ca 15 d.

A Shimadzu IR Affinity-1 Fourier transform infrared (FT–IR) spectrometer was used to record the FT–IR spectrum of I using the KBr pellet technique in the range 400–4000 cm⁻¹ (Fig. S8 of the supporting information). The absorption band at 1603 cm⁻¹ confirms the formation of the C=N groups. The aromatic ring C=C stretching vibrations are observed in the range 1468–1585 cm⁻¹. The aromatic C—H in-plane bending modes are observed in the region 1005–1292 cm⁻¹, whereas the out-of-plane bending modes are observed in the range 762–973 cm⁻¹.

The ¹H and ¹³C nuclear magnetic resonance (NMR) spectra of compound I (Fig. S9 of the supporting information) were recorded using a Bruker Advance Neo 400 MHz NMR spectrometer. Deuterated chloroform (CDCl₃-d) was employed as the solvent, with tetramethylsilane (TMS) serving as the internal standard. In the ¹H NMR spectrum of I, the singlet peak at 8.30 ppm is attributed to the azomethine (–N=CH–) proton, while signals observed at 7.73, 7.18, 7.16 and 6.89 ppm are attributed to the aromatic protons. Additionally, there are sharp singlet peaks at 3.80 ppm, corresponding to the methoxy protons (O—CH₃). The protons of the diethylamino group were detected at 1.19 ppm as a triplet (CH₃) and at 3.41 ppm as a quartet (CH₂). In the ¹³C NMR spectrum of I, the resonance at 158.70 ppm signifies the presence of the azomethine (–N=CH–) unit, 55.51 ppm is associated with the CH₃—O group, 44.51 ppm is related to the methylene C atoms of the (CH₃CH₂)₂—N group and 12.62 ppm corresponds to the methyl C atoms of the (CH₃CH₂)₂—N group.

An SDT Q600 V20.9 Build 20 TA instrument were used to measure the thermogravimetric analysis (TGA) and the differential thermal analysis (DTA) in the temperature range 303–723 K (Fig. S10 of the supporting information) with a heating rate of 20 K min⁻¹. A small peak observed at ∼377 K (Fig. S10) in the DTA curve corresponds to the melting point of the material. The material is stable up to 483 K, after which it starts to decompose.

8. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The C-bound H atoms were included in calculated positions and treated as riding atoms, with C—H = 0.94–0.98 Å and U_iso(H) = 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C) for other H atoms.

Table 3
Experimental details

Crystal data
Chemical formula	C₁₈H₂₂N₂O
M_r	282.37
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	250
a, b, c (Å)	8.3830 (7), 9.2872 (7), 11.2981 (9)
α, β, γ (°)	78.991 (6), 71.009 (6), 74.174 (6)
V (Å³)	795.14 (12)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.07
Crystal size (mm)	0.68 × 0.47 × 0.28

Data collection
Diffractometer	STOE IPDS II
Absorption correction	Multi-scan [X-RED32 (Stoe & Cie, 2018 ) and X-AREA LANA (Stoe & Cie, 2018)]
T_min, T_max	0.697, 0.989
No. of measured, independent and observed [I > 2σ(I)] reflections	11520, 3183, 2453
R_int	0.030
(sin θ/λ)_max (Å⁻¹)	0.622

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.035, 0.100, 1.04
No. of reflections	3183
No. of parameters	194
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.11, −0.10
Computer programs: X-AREA , X-RED32 and X-AREA LANA (Stoe & Cie, 2018), SHELXT2014 (Sheldrick, 2015a ), PLATON (Spek, 2020 ), Mercury (Macrae et al., 2020), SHELXL2018 (Sheldrick, 2015b ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 2325829

Crystal structure: contains datablocks I, Global. DOI: https://doi.org/10.1107/S2056989024000574/hb8091sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989024000574/hb8091Isup2.hkl

Table S1. Short contacts in the crystal structures of compounds I, II and III. Figs. S1-S10. Energy frameworks and FTIR, NMR and DSC and TGA data. DOI: https://doi.org/10.1107/S2056989024000574/hb8091sup3.pdf

Supporting information file. DOI: https://doi.org/10.1107/S2056989024000574/hb8091Isup4.cml

checkCIF report

Computing details top

(E)-N,N-Diethyl-4-{[(4-methoxyphenyl)imino]methyl}aniline top

Crystal data top

C₁₈H₂₂N₂O	Z = 2
M_r = 282.37	F(000) = 304
Triclinic, P1	D_x = 1.179 Mg m⁻³
a = 8.3830 (7) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.2872 (7) Å	Cell parameters from 8317 reflections
c = 11.2981 (9) Å	θ = 1.9–26.6°
α = 78.991 (6)°	µ = 0.07 mm⁻¹
β = 71.009 (6)°	T = 250 K
γ = 74.174 (6)°	Prism, yellow
V = 795.14 (12) Å³	0.68 × 0.47 × 0.28 mm

Data collection top

STOE IPDS II diffractometer	3183 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	2453 reflections with I > 2σ(I)
Plane graphite monochromator	R_int = 0.030
Detector resolution: 6.67 pixels mm^-1	θ_max = 26.2°, θ_min = 1.9°
rotation method, ω scans	h = −10→10
Absorption correction: multi-scan [X-RED32 (Stoe & Cie, 2018) and X-AREA LANA (Stoe & Cie, 2018)]	k = −11→11
T_min = 0.697, T_max = 0.989	l = −13→14
11520 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)] = 0.035	H-atom parameters constrained
wR(F²) = 0.100	w = 1/[σ²(F_o²) + (0.0477P)² + 0.076P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
3183 reflections	Δρ_max = 0.11 e Å⁻³
194 parameters	Δρ_min = −0.10 e Å⁻³
0 restraints	Extinction correction: (SHELXL2018; Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: dual	Extinction coefficient: 0.06 (1)

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
O1	0.90654 (10)	0.86089 (9)	0.06035 (8)	0.0546 (2)
N1	0.34566 (12)	0.58694 (11)	0.23619 (9)	0.0508 (3)
N2	−0.20580 (13)	0.16536 (11)	0.38486 (9)	0.0527 (3)
C1	0.77767 (14)	0.78348 (12)	0.10357 (10)	0.0454 (3)
C2	0.61011 (15)	0.87089 (12)	0.12118 (11)	0.0502 (3)
H2	0.591811	0.976243	0.103921	0.060*
C3	0.47095 (15)	0.80443 (13)	0.16366 (11)	0.0513 (3)
H3	0.358218	0.865153	0.176449	0.062*
C4	0.49434 (14)	0.64815 (12)	0.18812 (10)	0.0462 (3)
C5	0.66201 (14)	0.56221 (12)	0.17208 (11)	0.0490 (3)
H5	0.680241	0.456927	0.190073	0.059*
C6	0.80332 (14)	0.62806 (12)	0.13011 (11)	0.0486 (3)
H6	0.915970	0.567772	0.119672	0.058*
C7	0.34757 (14)	0.46457 (13)	0.19969 (10)	0.0491 (3)
H7	0.446601	0.421105	0.138215	0.059*
C8	0.20522 (14)	0.38883 (12)	0.24788 (10)	0.0459 (3)
C9	0.05732 (14)	0.43984 (12)	0.34505 (10)	0.0470 (3)
H9	0.049892	0.525924	0.380601	0.056*
C10	−0.07673 (14)	0.36818 (12)	0.38981 (11)	0.0474 (3)
H10	−0.173924	0.406192	0.455066	0.057*
C11	−0.07201 (14)	0.23796 (12)	0.33985 (10)	0.0445 (3)
C12	0.07565 (15)	0.18844 (13)	0.24069 (11)	0.0519 (3)
H12	0.083149	0.103674	0.203407	0.062*
C13	0.20913 (15)	0.26207 (13)	0.19749 (11)	0.0520 (3)
H13	0.306292	0.225458	0.131648	0.062*
C14	1.07994 (16)	0.77581 (15)	0.04265 (14)	0.0675 (4)
H14A	1.106339	0.705115	−0.017850	0.101*
H14B	1.093169	0.721030	0.122330	0.101*
H14C	1.158592	0.843244	0.011381	0.101*
C15	−0.20452 (17)	0.03482 (13)	0.33003 (12)	0.0570 (3)
H15A	−0.153911	0.050389	0.238532	0.068*
H15B	−0.324234	0.027042	0.346349	0.068*
C16	−0.1037 (2)	−0.11202 (15)	0.38128 (16)	0.0778 (4)
H16A	−0.152434	−0.128065	0.471944	0.117*
H16B	0.016571	−0.107421	0.361391	0.117*
H16C	−0.110656	−0.194522	0.343312	0.117*
C17	−0.34025 (16)	0.19415 (14)	0.50416 (11)	0.0563 (3)
H17A	−0.297730	0.241588	0.554642	0.068*
H17B	−0.362182	0.097789	0.551020	0.068*
C18	−0.50769 (18)	0.29363 (18)	0.48748 (15)	0.0770 (4)
H18A	−0.551352	0.247013	0.438293	0.115*
H18B	−0.488023	0.390729	0.443997	0.115*
H18C	−0.591789	0.307371	0.569374	0.115*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0506 (5)	0.0498 (5)	0.0639 (5)	−0.0138 (4)	−0.0168 (4)	−0.0036 (4)
N1	0.0456 (6)	0.0515 (6)	0.0536 (6)	−0.0091 (4)	−0.0137 (4)	−0.0055 (4)
N2	0.0531 (6)	0.0540 (6)	0.0532 (6)	−0.0159 (5)	−0.0113 (4)	−0.0133 (4)
C1	0.0484 (6)	0.0478 (6)	0.0415 (6)	−0.0113 (5)	−0.0146 (5)	−0.0054 (5)
C2	0.0542 (7)	0.0418 (6)	0.0536 (7)	−0.0063 (5)	−0.0176 (5)	−0.0057 (5)
C3	0.0449 (6)	0.0499 (6)	0.0549 (7)	−0.0006 (5)	−0.0156 (5)	−0.0090 (5)
C4	0.0447 (6)	0.0500 (6)	0.0429 (6)	−0.0086 (5)	−0.0125 (5)	−0.0063 (5)
C5	0.0498 (7)	0.0429 (6)	0.0522 (6)	−0.0072 (5)	−0.0151 (5)	−0.0045 (5)
C6	0.0433 (6)	0.0478 (6)	0.0514 (6)	−0.0039 (5)	−0.0150 (5)	−0.0053 (5)
C7	0.0447 (6)	0.0547 (7)	0.0457 (6)	−0.0067 (5)	−0.0133 (5)	−0.0065 (5)
C8	0.0458 (6)	0.0494 (6)	0.0424 (6)	−0.0074 (5)	−0.0154 (5)	−0.0052 (5)
C9	0.0508 (7)	0.0436 (6)	0.0475 (6)	−0.0077 (5)	−0.0152 (5)	−0.0099 (5)
C10	0.0463 (6)	0.0469 (6)	0.0457 (6)	−0.0054 (5)	−0.0099 (5)	−0.0110 (5)
C11	0.0463 (6)	0.0452 (6)	0.0435 (6)	−0.0077 (5)	−0.0172 (5)	−0.0052 (5)
C12	0.0559 (7)	0.0516 (6)	0.0503 (6)	−0.0089 (5)	−0.0146 (5)	−0.0169 (5)
C13	0.0473 (6)	0.0591 (7)	0.0466 (6)	−0.0063 (5)	−0.0090 (5)	−0.0155 (5)
C14	0.0482 (7)	0.0648 (8)	0.0862 (10)	−0.0149 (6)	−0.0186 (7)	0.0009 (7)
C15	0.0620 (8)	0.0554 (7)	0.0608 (7)	−0.0179 (6)	−0.0205 (6)	−0.0118 (6)
C16	0.0840 (10)	0.0547 (8)	0.0908 (11)	−0.0109 (7)	−0.0250 (8)	−0.0068 (7)
C17	0.0576 (7)	0.0601 (7)	0.0518 (7)	−0.0212 (6)	−0.0100 (5)	−0.0065 (6)
C18	0.0587 (8)	0.0865 (10)	0.0785 (10)	−0.0084 (7)	−0.0123 (7)	−0.0176 (8)

Geometric parameters (Å, º) top

O1—C1	1.3669 (13)	C9—H9	0.9400
O1—C14	1.4220 (14)	C10—C11	1.4153 (15)
N1—C7	1.2754 (15)	C10—H10	0.9400
N1—C4	1.4140 (14)	C11—C12	1.4081 (16)
N2—C11	1.3716 (14)	C12—C13	1.3756 (16)
N2—C15	1.4592 (14)	C12—H12	0.9400
N2—C17	1.4639 (15)	C13—H13	0.9400
C1—C6	1.3882 (16)	C14—H14A	0.9700
C1—C2	1.3891 (15)	C14—H14B	0.9700
C2—C3	1.3739 (16)	C14—H14C	0.9700
C2—H2	0.9400	C15—C16	1.5158 (19)
C3—C4	1.3958 (16)	C15—H15A	0.9800
C3—H3	0.9400	C15—H15B	0.9800
C4—C5	1.3868 (15)	C16—H16A	0.9700
C5—C6	1.3859 (15)	C16—H16B	0.9700
C5—H5	0.9400	C16—H16C	0.9700
C6—H6	0.9400	C17—C18	1.5025 (19)
C7—C8	1.4505 (16)	C17—H17A	0.9800
C7—H7	0.9400	C17—H17B	0.9800
C8—C13	1.3907 (15)	C18—H18A	0.9700
C8—C9	1.3997 (15)	C18—H18B	0.9700
C9—C10	1.3678 (15)	C18—H18C	0.9700

C1—O1—C14	117.48 (9)	C12—C11—C10	116.55 (10)
C7—N1—C4	119.31 (10)	C13—C12—C11	121.08 (10)
C11—N2—C15	121.61 (9)	C13—C12—H12	119.5
C11—N2—C17	122.15 (9)	C11—C12—H12	119.5
C15—N2—C17	115.20 (9)	C12—C13—C8	122.25 (10)
O1—C1—C6	124.99 (10)	C12—C13—H13	118.9
O1—C1—C2	115.67 (9)	C8—C13—H13	118.9
C6—C1—C2	119.35 (10)	O1—C14—H14A	109.5
C3—C2—C1	120.45 (10)	O1—C14—H14B	109.5
C3—C2—H2	119.8	H14A—C14—H14B	109.5
C1—C2—H2	119.8	O1—C14—H14C	109.5
C2—C3—C4	121.04 (10)	H14A—C14—H14C	109.5
C2—C3—H3	119.5	H14B—C14—H14C	109.5
C4—C3—H3	119.5	N2—C15—C16	113.41 (11)
C5—C4—C3	117.97 (10)	N2—C15—H15A	108.9
C5—C4—N1	123.58 (10)	C16—C15—H15A	108.9
C3—C4—N1	118.30 (10)	N2—C15—H15B	108.9
C6—C5—C4	121.49 (10)	C16—C15—H15B	108.9
C6—C5—H5	119.3	H15A—C15—H15B	107.7
C4—C5—H5	119.3	C15—C16—H16A	109.5
C5—C6—C1	119.68 (10)	C15—C16—H16B	109.5
C5—C6—H6	120.2	H16A—C16—H16B	109.5
C1—C6—H6	120.2	C15—C16—H16C	109.5
N1—C7—C8	123.56 (11)	H16A—C16—H16C	109.5
N1—C7—H7	118.2	H16B—C16—H16C	109.5
C8—C7—H7	118.2	N2—C17—C18	113.31 (11)
C13—C8—C9	116.81 (10)	N2—C17—H17A	108.9
C13—C8—C7	120.93 (10)	C18—C17—H17A	108.9
C9—C8—C7	122.25 (10)	N2—C17—H17B	108.9
C10—C9—C8	121.97 (10)	C18—C17—H17B	108.9
C10—C9—H9	119.0	H17A—C17—H17B	107.7
C8—C9—H9	119.0	C17—C18—H18A	109.5
C9—C10—C11	121.32 (10)	C17—C18—H18B	109.5
C9—C10—H10	119.3	H18A—C18—H18B	109.5
C11—C10—H10	119.3	C17—C18—H18C	109.5
N2—C11—C12	121.94 (10)	H18A—C18—H18C	109.5
N2—C11—C10	121.51 (10)	H18B—C18—H18C	109.5

C14—O1—C1—C6	−0.78 (16)	C7—C8—C9—C10	179.79 (10)
C14—O1—C1—C2	179.17 (10)	C8—C9—C10—C11	0.15 (17)
O1—C1—C2—C3	179.63 (10)	C15—N2—C11—C12	−1.67 (16)
C6—C1—C2—C3	−0.42 (16)	C17—N2—C11—C12	166.16 (11)
C1—C2—C3—C4	−1.05 (17)	C15—N2—C11—C10	177.40 (10)
C2—C3—C4—C5	2.01 (17)	C17—N2—C11—C10	−14.76 (16)
C2—C3—C4—N1	177.64 (10)	C9—C10—C11—N2	179.70 (10)
C7—N1—C4—C5	−41.89 (16)	C9—C10—C11—C12	−1.18 (16)
C7—N1—C4—C3	142.74 (11)	N2—C11—C12—C13	−179.49 (10)
C3—C4—C5—C6	−1.56 (17)	C10—C11—C12—C13	1.38 (17)
N1—C4—C5—C6	−176.95 (10)	C11—C12—C13—C8	−0.58 (18)
C4—C5—C6—C1	0.15 (17)	C9—C8—C13—C12	−0.49 (17)
O1—C1—C6—C5	−179.19 (10)	C7—C8—C13—C12	−179.59 (11)
C2—C1—C6—C5	0.86 (16)	C11—N2—C15—C16	83.50 (15)
C4—N1—C7—C8	176.85 (10)	C17—N2—C15—C16	−85.13 (14)
N1—C7—C8—C13	174.93 (11)	C11—N2—C17—C18	102.52 (13)
N1—C7—C8—C9	−4.12 (17)	C15—N2—C17—C18	−88.92 (13)
C13—C8—C9—C10	0.70 (16)

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C1–C6 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C13—H13···Cg1ⁱ	0.94	2.98	3.659 (1)	130

Symmetry code: (i) −x+1, −y+1, −z.

Relative percentage contributions of close contacts to the Hirshfeld surfaces of compounds I, II and III. top

IIa and IIb refer to the two independent molecules of compound II'

Contact	I	II	IIa	IIb	III
H···H	62.5	58.1	53.9	55.2	59.5
C···H/H···C	26.6	29.4	34.3	32.0	29.8
N···H/H···N	5.1	6.3	5.6	6.5	5.9
O···H/H···O	5.4	6.0	6.0	6.2	4.6

Acknowledgements

The authors thank the School of Advanced Sciences, Vellore Institute of Technology, Vellore, for the use of their instrumentation facilities, such as FT–IR and thermal analyses. HSE is grateful to the University of Neuchâtel for their support over the years.

References

Afzal, S., Akhter, Z. & Tahir, M. N. (2012). Acta Cryst. E68, o1789. CSD CrossRef IUCr Journals Google Scholar
Al-Masri, H. T., Sieler, J., Lönnecke, P., Blaurock, S., Domasevitch, K. & Hey-Hawkins, E. (2004). Tetrahedron, 60, 333–339. CAS Google Scholar
Boulechfar, C., Ferkous, H., Delimi, A., Djedouani, A., Kahlouche, A., Boublia, A., Darwish, A., Lemaoui, T., Verma, R. & Benguerba, Y. (2023). Inorg. Chem. Commun. 150, 110451. CrossRef Google Scholar
Brodowska, K. & Łodyga-Chruścińska, E. (2014). CHEMIK, 68, 132–134. Google Scholar
Bürgi, H. B. & Dunitz, J. D. (1970). Helv. Chim. Acta, 53, 1747–1764. CSD CrossRef Web of Science Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Han, T., Wei, W., Yuan, J., Duan, Y., Li, Y., Hu, L. & Dong, Y. (2016). Talanta, 150, 104–112. CSD CrossRef CAS PubMed Google Scholar
Iqbal, M. Z., Farooq, H. M., Zaman, M. Q., Gulzar, A. & Shah, H. U. (1995). J. Anal. Appl. Pyrolysis, 35, 109–120. CrossRef CAS Google Scholar
Kumari, R., Seera, R., De, A., Ranjan, R. & Guru Row, T. N. (2019). Cryst. Growth Des. 19, 5934–5944. CSD CrossRef CAS Google Scholar
Lee, H.-J., Jeong, J.-M., Rai, G., Lee, Y.-S., Chang, Y.-S., Kim, Y.-J., Kim, H.-W., Lee, D.-S., Chung, J.-K., Mook-Jung, I. & Lee, M.-C. (2009). Nucl. Med. Biol. 36, 107–116. CrossRef PubMed CAS Google Scholar
Li, X.-F. (2010). Acta Cryst. E66, o2417. Web of Science CSD CrossRef IUCr Journals Google Scholar
Macrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226–235. Web of Science CrossRef CAS IUCr Journals Google Scholar
Rodrigues, J. J. Jr, Misoguti, L., Nunes, F. D. C. R., Mendonça, C. R. & Zilio, S. C. (2003). Opt. Mater. 22, 235–240. CrossRef CAS Google Scholar
Ruanwas, P., Chantrapromma, S. & Fun, H.-K. (2012). Acta Cryst. E68, o2155–o2156. CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spackman, P. R., Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J., Jayatilaka, D. & Spackman, M. A. (2021). J. Appl. Cryst. 54, 1006–1011. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2020). Acta Cryst. E76, 1–11. Web of Science CrossRef IUCr Journals Google Scholar
Stoe & Cie (2018). X-AREA, X-RED32 and X-AREA LANA. Stoe & Cie GmbH, Damstadt, Germany. Google Scholar
Sun, H., Chen, S., Jin, J., Sun, R., Sun, J., Liu, D., Liu, Z., Zeng, J., Zhu, Y., Niu, J. & Lu, S. (2023). J. Photochem. Photobiol. Chem. 441, 114730–114745. CSD CrossRef CAS Google Scholar
Sundararaman, L., Ramu, H., Kandaswamy, R. & Stoeckli-Evans, H. (2009). Acta Cryst. E65, o477. CSD CrossRef IUCr Journals Google Scholar
Sunil, K., Kumara, T. P. P., Kumar, B. A. & Patel, S. B. (2021). Pharm. Chem. J. 55, 46–53. CrossRef CAS Google Scholar
Tan, S. L., Jotani, M. M. & Tiekink, E. R. T. (2019). Acta Cryst. E75, 308–318. Web of Science CrossRef IUCr Journals Google Scholar
Wang, Q. & Wang, D.-Q. (2008). Acta Cryst. E64, o51. Web of Science CSD CrossRef IUCr Journals Google Scholar
Wen, S., Liu, J., Qiu, M., Li, Y., Zhu, D., Gu, C., Han, L. & Yang, R. (2015). RSC Adv. 5, 5875–5878. CSD CrossRef CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Weszka, J., Domanski, M., Jarzabek, B., Jurusik, J., Cisowski, J. & Burian, A. (2008). Thin Solid Films, 516, 3098–3104. CrossRef CAS Google Scholar
Xochicale-Santana, L., López-Espejel, M., Jiménez-Pérez, V. M., Lara-Cerón, J., Gómez-Treviño, A., Waksman, N., Dias, H. V. R. & Muñoz-Flores, B. M. (2021). New J. Chem. 45, 17183–17189. CAS Google Scholar
Zhang, F.-G. (2010). Acta Cryst. E66, o382. Web of Science CSD CrossRef IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.