Crystal structure and Hirshfeld surface analysis of (E)-3-(3-iodo-phen-yl)-1-(4-iodo-phen-yl)prop-2-en-1-one.

The title compound, C15H10I2O, is a halogenated chalcone formed from two iodine substituted rings, one para-substituted and the other meta-substituted, linked through a prop-2-en-1-one spacer. In the mol-ecule, the mean planes of the 3-iodo-phenyl and the 4-iodo-phenyl groups are twisted by 46.51 (15)°. The calculated electrostatic potential surfaces show the presence of σ-holes on both substituted iodines. In the crystal, the mol-ecules are linked through type II halogen bonds, forming a sheet structure parallel to the bc plane. Between the sheets, weak inter-molecular C-H⋯π inter-actions are observed. Hirshfeld surface analysis showed that the most significant contacts in the structure are C⋯H/H⋯C (31.9%), followed by H⋯H (21.4%), I⋯H/H⋯I (18.4%). I⋯I (14.5%) and O⋯H/H⋯O (8.1%). © Spruce et al. 2020.

Chemical context

Chalcones are aromatic ketones which have shown potential as anti­bacterial, anti­fungal and anti-inflammatory agents (D’silva et al., 2011 ▸). These mol­ecules are essential to the biosynthesis of flavonoids through a conjugate ring-closure to form flavone and have also attracted attention for their potential use in opto- and organic electronics (Shetty et al., 2016 ▸, 2017 ▸). As a family of mol­ecules, substituted chalcones can be readily synthesized via a Claisen–Schmidt condensation reaction between an appropriately functionalized aceto­phenone and benzaldehyde. Substitutions on each of the benzene rings are currently being investigated in order to inter­rogate how the electronic properties of the crystal are altered. The iodo-substituted rings present in the title compound allows for the formation of iodine channels in the crystal, a conformation which may afford a change in the crystal’s electrical properties.

Structural commentary

The title compound comprises two aromatic rings, 4-iodo­phenyl (1-Ring) and 3-iodo­phenyl (3-Ring), which are connected, respectively, to atoms C1 and C3 of the –CO—CH=CH– enone bridge (Fig. 1 ▸). The backbone torsion angles are C5—C4—C1—C2 = 151.6 (4)°, C4—C1—C2—C3 = 171.9 (4)°, C1—C2—C3—C10 = 176.4 (4)° and C2—C3—C10—C11 = 170.4 (5)°. The mean planes of the 3-iodo­phenyl and 4-iodo­phenyl groups are twisted by 46.51 (15)° relative to each other. The H atoms of the propenone group are trans-configured.

Figure 1

The mol­ecular structure of the title compound, showing the atom labelling and displacement ellipsoids drawn at the 50% probability level.

Supra­molecular features

Electrostatic potential surfaces [Fig. 2 ▸(a)–(c)] show the presence of σ-holes on both substituted iodines, I1 and I2, which allow for halogen bonding of a bifurcated type II. Partial packing diagrams are shown in Fig. 3 ▸(a)–(c). Inter­estingly, these halogen bonds form exclusively between equivalent iodine atoms, either para–para or meta–meta. The geometries of the halogen bonds are I1⋯I1iv = 4.0980 (9) Å, C7—I1⋯I1iv = 113.85 (13)°, I1⋯I1v =4.0980 (9) Å and C7—I⋯I1v = 154.47 (13)° for the para–para I⋯I bonds, and I2⋯I2vi = 3.9805 (8) Å, C12—I2⋯I2vi = 108.20 (13)°, I2⋯I2vii = 3.9805 (8) Å and C12—I2⋯I2vii = 157.30 (13)° for the meta–meta I⋯I bonds [symmetry codes: (iv) x,  − y, − + z; (v) x,  − y,  + z; (vi) x,  − y,  + z; (vii) x,  − y, − + z]. A sheet structure is formed parallel to the bc plane. There are also three weak C—H⋯π inter­actions (Table 1 ▸) between the sheets.

Figure 2

Electrostatic potential mapped onto an electron density isosurface with isovalue 0.02 e Å−3, calculated using B3LYP at the LANL2DZ level. Red and blue regions show negative and positive electric potentials, respectively. (a) shows the potential of the substituted chalcone mol­ecule. (b) and (c) show the σ-holes on 1-Ring and 3-Ring, respectively.

Figure 3

(a) A packing diagram of the title compound in the unit cell. Red, green and blue axes indicate a, b and c, respectively. (b) Meta–meta and para–para halogen bonds indicated by dashed lines. (c) Three weak C—H⋯π inter­actions (dashed lines; C5—H5⋯Cg1i, C8—H8⋯Cg1ii and C14—H14⋯Cg2iii). Cg1 and Cg2 are the centroids of the C10–C15 and C4–C9 rings, respectively. [Symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) 2 − x, 1 − y, 2 − z; (iii) 1 − x, 1 − y, 2 − z; (iv) x,  − y, − + z; (v) x,  − y,  + z; (vi) x,  − y,  + z; (vii) x,  − y, − + z..]

Table 1

Hydrogen-bond geometry (Å, °)

Cg1 and Cg2 are the centroids of the C10–C15 and C4–C9 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5⋯Cg1i	0.95	2.78	3.406 (5)	124
C8—H8⋯Cg1ii	0.95	2.85	3.491 (5)	126
C14—H14⋯Cg2iii	0.95	2.77	3.440 (5)	129

Symmetry codes: (i) ; (ii) ; (iii) .

Hirshfeld surfaces, mapped over d norm, shape-index and d e, and two-dimensional fingerprint plots of the title compound were calculated using CrystalExplorer17.5 (Turner et al., 2017 ▸). Hirshfeld surfaces [Fig. 4 ▸(a) and (c)] highlight the relationship between the contact distance and the van der Waals radii (Venkatesan et al., 2016 ▸). The Hirshfeld surface mapped over the shape-index [Fig. 4 ▸(b)] shows depressions on both 1-Ring and 3-Ring, which is indicative of C—H⋯π inter­actions. Two-dimensional fingerprint plots are used to illustrate the inter­molecular contacts between mol­ecules within the crystal structure. The fingerprint plots of all significant inter­actions are shown in Fig. 5 ▸(a)–(f). C⋯H/H⋯C contacts [Fig. 5 ▸(b)] make the largest contribution (31.9%) and show a pair of spikes at d e + d i = ∼2.8 Å, representative of inter­molecular C—H⋯π inter­actions. The O⋯H/H⋯O plot also contains a pair of spikes at d e + d i = ∼2.7 Å [Fig. 5 ▸(f)]. The negligible contributions from other contacts, not included in Fig. 5 ▸, are as follows: C⋯C (3.1%), C⋯O/O⋯C (2.1%) and C⋯I/I⋯C (0.5%).

Figure 4

Hirshfeld surfaces of the title compound, mapped with (a) d norm, where white regions represent inter­actions equal to, and blue regions represent inter­actions shorter than the sum of their van der Waals radii, (b) the shape-index, and (c) d e, where the circled areas indicate the C—H⋯π inter­actions.

Figure 5

Hirshfeld surfaces and fingerprint plots showing percentage of contacts of (a) all inter­actions, (b) C⋯H/H⋯C, (c) H⋯H, (d) I⋯H/H⋯I, (e) I⋯I and (f) O⋯H/H⋯O. inter­actions.

Database survey

A survey of the Cambridge Structural Database (CSD; Groom et al., 2016 ▸) showed that existing similar structures include (2E)-1-(4-bromo­phen­yl)-3-(4-fluoro­phen­yl)prop-2-en-1-one (refcode NURCIN; Dutkiewicz et al., 2010 ▸), 1-(4-bromo­phen­yl)-3-(4-chloro­phen­yl)prop-2-en-1-one (LEPYIP; Yang et al., 2006 ▸), 1,3-bis­(4-bromo­phen­yl)prop-2-en-1-one (LEHROG; Ng et al., 2006 ▸), (E)-1-(4-bromo­phen­yl)-3-(4-iodo­phen­yl)prop-2-en-1-one (IWALAV; Zainuri et al., 2017 ▸) and 3-(3-bromo­phen­yl)-1-(4-bromo­phen­yl)prop-2-en-1-one (ODEDEH; Teh et al., 2006 ▸). Four compounds (NURCIN, LEPYIP, LEHROG and IWALAV) contain only para-substituted rings. Within these structures, halogen bonds exist only between bromine and iodine species, and never between equivalent halogens. 3-(3-Bromo­phen­yl)-1-(4-bromo­phen­yl)prop-2-en-1-one contains one meta-substituted ring and one para-substituted ring: each halogen bond exists between rings with the same substitution, either para–para or meta–meta, as seen in the title compound.

Synthesis and crystallization

4′-Iodo­aceto­phenone (0.773 g, 3.14 mmol), 3-iodo­benzaldehyde (0.697 g, 3.00), anhydrous zinc chloride (0.615 g, 4.51 mmol) and absolute ethanol (1.5 ml) were added to a microwave vessel with a stir bar. Using a microwave reactor, the reaction mixture was heated to 468 K for 15 minutes. Upon cooling the reaction, yellowish solids were collected by vacuum filtration and washed with 95% ethanol. The resulting solid was recrystallized from 95% ethanol (0.603 g, 44% yield, yellow crystals, m.p. 442.5–443.7 K). 1H NMR (400 MHz, DMSO-d 6, referenced to TMS): δ (ppm) 8.37 (1H, s), 8.0–7.94 (5H, m), 7.88 (1H, d, J = 8 Hz), 7.81 (1H, d, J = 8 Hz), 7.68 (1H, d, J = 16 Hz), 7.26 (1H, t, J = 8 Hz). 13C NMR (100 MHz, DMSO-d 6, referenced to solvent, 39.52 ppm): δ (ppm) 188.44, 142.75, 139.04, 137.72, 136.95, 136.66, 136.61, 130.89, 130.38, 128.73, 122.81, 102.14, 95.57. Single crystals suitable for X-ray diffraction were obtained by the slow evaporation technique from an acetone solution at room temperature.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. H atoms were positioned geometrically (C—H = 0.95 Å) and refined using a riding model with U iso(H) = 1.2U eq(C).

Table 2

Experimental details

Crystal data
Chemical formula	C15H10I2O
M r	460.03
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	200
a, b, c (Å)	7.2650 (7), 32.864 (3), 5.8446 (6)
β (°)	92.277 (2)
V (Å3)	1394.3 (2)
Z	4
Radiation type	Mo Kα
μ (mm−1)	4.50
Crystal size (mm)	0.57 × 0.29 × 0.08
Data collection
Diffractometer	Bruker APEXII kappa CCD area detector
Absorption correction	Numerical (SADABS; Bruker, 2016 ▸)
T min, T max	0.065, 0.189
No. of measured, independent and observed [I > 2σ(I)] reflections	18346, 3215, 2960
R int	0.021
(sin θ/λ)max (Å−1)	0.650
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.037, 0.073, 1.27
No. of reflections	3215
No. of parameters	164
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	1.14, −1.31

Computer programs: SAINT (Bruker, 2016 ▸), SHELXT (Sheldrick, 2015a ▸), SHELXL2018 (Sheldrick, 2015b ▸) and OLEX2 (Dolomanov et al., 2009 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989019016402/is5526sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989019016402/is5526Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989019016402/is5526Isup5.mol

13C NMR of the synthesised product. DOI: 10.1107/S2056989019016402/is5526sup3.pdf

1H NMR of the synthesised product. DOI: 10.1107/S2056989019016402/is5526sup4.pdf

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989019016402/is5526Isup6.cml

CCDC reference: 1970266

Additional supporting information: crystallographic information; 3D view; checkCIF report

C15H10I2O	F(000) = 856
Mr = 460.03	Dx = 2.191 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.2650 (7) Å	Cell parameters from 8513 reflections
b = 32.864 (3) Å	θ = 2.5–27.5°
c = 5.8446 (6) Å	µ = 4.50 mm−1
β = 92.277 (2)°	T = 200 K
V = 1394.3 (2) Å3	Plate, clear colourless
Z = 4	0.57 × 0.29 × 0.08 mm

Bruker APEXII kappa CCD area detector diffractometer	3215 independent reflections
Radiation source: fine-focus sealed tube	2960 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
φ and ω scans	θmax = 27.5°, θmin = 2.5°
Absorption correction: numerical (SADABS; Bruker, 2016)	h = −9→9
Tmin = 0.065, Tmax = 0.189	k = −42→37
18346 measured reflections	l = −7→7

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.037	w = 1/[σ2(Fo2) + (0.0034P)2 + 6.4729P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.073	(Δ/σ)max = 0.001
S = 1.27	Δρmax = 1.14 e Å−3
3215 reflections	Δρmin = −1.30 e Å−3
164 parameters	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraints	Extinction coefficient: 0.00062 (7)
Primary atom site location: iterative

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.

	x	y	z	Uiso*/Ueq
C4	0.8336 (6)	0.43230 (13)	0.5707 (7)	0.0250 (9)
C9	0.9114 (6)	0.42521 (14)	0.7892 (8)	0.0278 (9)
H9	0.939830	0.447424	0.888449	0.033*
C8	0.9474 (6)	0.38548 (14)	0.8617 (8)	0.0289 (9)
H8	1.003866	0.380553	1.008533	0.035*
C7	0.9004 (6)	0.35322 (14)	0.7183 (8)	0.0292 (9)
C6	0.8265 (6)	0.35974 (14)	0.4992 (8)	0.0298 (10)
H6	0.797488	0.337429	0.400879	0.036*
C5	0.7955 (6)	0.39954 (14)	0.4252 (8)	0.0285 (9)
H5	0.747935	0.404397	0.273958	0.034*
C1	0.7892 (6)	0.47421 (14)	0.4874 (8)	0.0284 (9)
C2	0.7447 (6)	0.50560 (14)	0.6605 (8)	0.0294 (9)
H2	0.729579	0.497837	0.815221	0.035*
C3	0.7258 (6)	0.54438 (13)	0.5999 (8)	0.0268 (9)
H3	0.749373	0.550781	0.445302	0.032*
C10	0.6729 (6)	0.57825 (13)	0.7450 (7)	0.0251 (9)
C11	0.6878 (6)	0.61791 (13)	0.6589 (8)	0.0273 (9)
H11	0.740192	0.622248	0.514565	0.033*
C12	0.6264 (6)	0.65086 (13)	0.7836 (8)	0.0289 (9)
C13	0.5540 (6)	0.64548 (15)	0.9989 (8)	0.0322 (10)
H13	0.513741	0.668101	1.084900	0.039*
C14	0.5424 (6)	0.60607 (15)	1.0845 (8)	0.0311 (10)
H14	0.493446	0.601952	1.230991	0.037*
C15	0.6003 (6)	0.57271 (14)	0.9618 (8)	0.0280 (9)
H15	0.590951	0.546131	1.024224	0.034*
I1	0.92866 (6)	0.29371 (2)	0.84509 (7)	0.04484 (12)
I2	0.63173 (6)	0.70888 (2)	0.63477 (6)	0.04434 (12)
O1	0.7830 (5)	0.48192 (10)	0.2821 (6)	0.0376 (8)

	U11	U22	U33	U12	U13	U23
C4	0.022 (2)	0.027 (2)	0.026 (2)	0.0011 (17)	0.0023 (16)	0.0009 (17)
C9	0.027 (2)	0.028 (2)	0.028 (2)	−0.0020 (18)	−0.0031 (18)	−0.0029 (17)
C8	0.028 (2)	0.034 (2)	0.024 (2)	0.0032 (19)	−0.0031 (17)	0.0017 (18)
C7	0.027 (2)	0.026 (2)	0.034 (2)	0.0048 (18)	0.0022 (18)	0.0026 (18)
C6	0.029 (2)	0.029 (2)	0.031 (2)	0.0003 (18)	−0.0001 (18)	−0.0077 (18)
C5	0.028 (2)	0.033 (2)	0.024 (2)	0.0036 (18)	−0.0010 (17)	−0.0009 (17)
C1	0.023 (2)	0.031 (2)	0.031 (2)	0.0005 (17)	0.0008 (18)	0.0024 (18)
C2	0.033 (2)	0.028 (2)	0.027 (2)	−0.0004 (18)	0.0022 (18)	0.0019 (17)
C3	0.026 (2)	0.029 (2)	0.026 (2)	−0.0005 (18)	0.0003 (17)	0.0016 (17)
C10	0.021 (2)	0.030 (2)	0.025 (2)	−0.0016 (17)	−0.0045 (16)	0.0015 (17)
C11	0.027 (2)	0.029 (2)	0.026 (2)	−0.0048 (18)	−0.0012 (17)	0.0022 (17)
C12	0.031 (2)	0.024 (2)	0.031 (2)	−0.0037 (18)	−0.0077 (18)	0.0016 (17)
C13	0.028 (2)	0.035 (2)	0.033 (2)	0.0014 (19)	−0.0018 (19)	−0.0073 (19)
C14	0.028 (2)	0.041 (3)	0.024 (2)	−0.002 (2)	−0.0003 (18)	−0.0015 (19)
C15	0.025 (2)	0.030 (2)	0.028 (2)	0.0001 (18)	−0.0048 (17)	0.0043 (18)
I1	0.0555 (2)	0.02652 (17)	0.0520 (2)	0.00766 (15)	−0.00426 (16)	0.00411 (14)
I2	0.0618 (3)	0.02421 (16)	0.0466 (2)	−0.00405 (15)	−0.00256 (16)	0.00229 (14)
O1	0.051 (2)	0.0340 (18)	0.0278 (17)	0.0045 (16)	0.0029 (15)	0.0051 (14)

C4—C9	1.395 (6)	C2—C3	1.328 (6)
C4—C5	1.393 (6)	C3—H3	0.9500
C4—C1	1.492 (6)	C3—C10	1.460 (6)
C9—H9	0.9500	C10—C11	1.403 (6)
C9—C8	1.394 (6)	C10—C15	1.403 (6)
C8—H8	0.9500	C11—H11	0.9500
C8—C7	1.386 (6)	C11—C12	1.388 (6)
C7—C6	1.386 (6)	C12—C13	1.394 (7)
C7—I1	2.099 (4)	C12—I2	2.097 (4)
C6—H6	0.9500	C13—H13	0.9500
C6—C5	1.393 (6)	C13—C14	1.392 (7)
C5—H5	0.9500	C14—H14	0.9500
C1—C2	1.490 (6)	C14—C15	1.385 (7)
C1—O1	1.225 (5)	C15—H15	0.9500
C2—H2	0.9500
C9—C4—C1	121.8 (4)	C3—C2—H2	119.8
C5—C4—C9	119.5 (4)	C2—C3—H3	116.4
C5—C4—C1	118.6 (4)	C2—C3—C10	127.1 (4)
C4—C9—H9	120.0	C10—C3—H3	116.4
C8—C9—C4	119.9 (4)	C11—C10—C3	118.3 (4)
C8—C9—H9	120.0	C11—C10—C15	118.8 (4)
C9—C8—H8	120.2	C15—C10—C3	122.8 (4)
C7—C8—C9	119.6 (4)	C10—C11—H11	119.8
C7—C8—H8	120.2	C12—C11—C10	120.4 (4)
C8—C7—I1	118.8 (3)	C12—C11—H11	119.8
C6—C7—C8	121.2 (4)	C11—C12—C13	121.0 (4)
C6—C7—I1	120.0 (3)	C11—C12—I2	118.7 (3)
C7—C6—H6	120.5	C13—C12—I2	120.2 (3)
C7—C6—C5	118.9 (4)	C12—C13—H13	120.9
C5—C6—H6	120.5	C14—C13—C12	118.2 (4)
C4—C5—C6	120.7 (4)	C14—C13—H13	120.9
C4—C5—H5	119.6	C13—C14—H14	119.1
C6—C5—H5	119.6	C15—C14—C13	121.8 (4)
C2—C1—C4	117.9 (4)	C15—C14—H14	119.1
O1—C1—C4	120.6 (4)	C10—C15—H15	120.1
O1—C1—C2	121.4 (4)	C14—C15—C10	119.8 (4)
C1—C2—H2	119.8	C14—C15—H15	120.1
C3—C2—C1	120.4 (4)
C4—C9—C8—C7	−1.9 (7)	C2—C3—C10—C11	170.4 (5)
C4—C1—C2—C3	171.9 (4)	C2—C3—C10—C15	−12.5 (7)
C9—C4—C5—C6	2.9 (7)	C3—C10—C11—C12	175.2 (4)
C9—C4—C1—C2	−28.3 (6)	C3—C10—C15—C14	−176.0 (4)
C9—C4—C1—O1	154.5 (5)	C10—C11—C12—C13	1.9 (7)
C9—C8—C7—C6	3.3 (7)	C10—C11—C12—I2	−175.0 (3)
C9—C8—C7—I1	−173.2 (3)	C11—C10—C15—C14	1.0 (6)
C8—C7—C6—C5	−1.5 (7)	C11—C12—C13—C14	−0.9 (7)
C7—C6—C5—C4	−1.6 (7)	C12—C13—C14—C15	0.0 (7)
C5—C4—C9—C8	−1.1 (7)	C13—C14—C15—C10	0.0 (7)
C5—C4—C1—C2	151.6 (4)	C15—C10—C11—C12	−1.9 (6)
C5—C4—C1—O1	−25.6 (7)	I1—C7—C6—C5	175.0 (3)
C1—C4—C9—C8	178.8 (4)	I2—C12—C13—C14	175.9 (3)
C1—C4—C5—C6	−177.0 (4)	O1—C1—C2—C3	−10.9 (7)
C1—C2—C3—C10	176.4 (4)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···Cg1i	0.95	2.78	3.406 (5)	124
C8—H8···Cg1ii	0.95	2.85	3.491 (5)	126
C14—H14···Cg2iii	0.95	2.77	3.440 (5)	129