research communications
and Hirshfeld analysis of 3′-bromo-4-methylchalcone and 3′-cyano-4-methylchalcone
aDepartment of Chemistry & Biochemistry, Gonzaga University, 502 E Boone Ave, Spokane, WA 99258, USA, bDepartment of Chemistry, Whitworth University, 300 W. Hawthorne Rd, Spokane, WA 99251, USA, and cSchool of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, England
*Correspondence e-mail: cremeens@gonzaga.edu
Two crystal structures of versus cyano. The compounds are 3′-bromo-4-methylchalcone [systematic name: 1-(2-bromophenyl)-3-(4-methylphenyl)prop-2-en-1-one], C16H13BrO, and 3′-cyano-4-methylchalcone {systematic name: 2-[3-(4-methylphenyl)prop-2-enoyl]benzonitrile}, C17H13NO. Both meaningfully add to the large dataset of chalcone structures. The of 3′-cyano-4-methylchalcone exhibits close contacts with the cyano nitrogen that do not appear in previously reported disubstituted cyanochalcones, namely interactions between the cyano nitrogen atom and a ring hydrogen atom as well as a methyl hydrogen atom. The structure of 3′-bromo-4-methylchalcone exhibits a type I halogen bond, similar to that found in a previously reported structure for 4-bromo-3′-methylchalcone.
or 1,3-diarylprop-2-en-1-ones, are presented; both contain a methyl substitution on the 3-Ring, but differ on the 1-Ring, bromoKeywords: crystal structure; chalcone; bromo; cyano; halogen bond; π stacking; edge-to-face.
1. Chemical context
α,β-unsaturated ketone, or enone. Interest in chalcone molecules has risen because of their potential pharmaceutical properties, electronic properties, and straightforward synthesis via a Claisen–Schmidt condensation between a benzaldehyde and acetophenone (Zhuang et al., 2017). Pharmaceutical attributes shown by some include antioxidant, anti-inflammatory, anti-cancer, and cytotoxic properties (Sahu et al., 2012). Additionally, some have been shown to be fluorescent, making them potential probes for mechanistic investigations and imaging (Lee et al., 2012).
are organic molecules commonly found in nature consisting of two phenyl rings connected by anThis paper compares the structure and packing of two newly crystallized chalcone molecules, 3′-cyano-4-methylchalcone [Sm6p] or m′CNpCH3 and 3′-bromo-4-methylchalcone [Dm6p] or m′BrpCH3, where Sm6p and Dm6p are internal codes tied to a large, long-term project. Each chalcone examined consists of a variable meta substitution at C6 of the 1-Ring, and methyl substitution at C13 of the 3-Ring, see Figs. 1 and 2. Substitution on the 1-Ring has been utilized to further understand the packing and structure of chalcone crystals based upon their ring substituents.
2. Structural commentary
The m′CNpCH3 and m′BrpCH3, differ at the meta position on the 1-Ring, cyano and bromo respectively, Figs. 1 and 2. Note that the following summary of dihedrals, which represents the planarity of the references data in Table 1 where non-rounded angles and errors can be found. The enone core exhibits small (10–11°) deviations from planarity (Φ2) for m′CNpCH3 and m′BrpCH3. The 1-Ring/carbonyl twists (Φ1) show similar deviations from planarity (25–27°) for m′CNpCH3 and m′BrpCH3. The 3-Ring/alkene twists (Φ3) also show similar deviations from planarity (16–18°) for m′CNpCH3 and m′BrpCH3. m′CNpCH3 and m′BrpCH3 exhibit similar 1-Ring/3-Ring twist angles (approximately 49°) and fold angles (1–2°). Based on the angle values, m′CNpCH3 and m′BrpCH3 do not vary greatly in torsions despite their different substituents. Both are similarly twisted and show a pairwise antiparallel arrangement of the enone core (Fig. 3), which are related by inversion symmetry. A closer look at the supramolecular properties (see below) reveals similarities and differences for the crystal structures.
under observation,
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3. Supramolecular features
Electrostatic potentials are shown in Fig. 4, and Hirshfeld analyses are presented in Figs. 5–7 for m′CNpCH3 and m′BrpCH3. The electrostatic potentials show a greater polarization for m′CNpCH3 than for m′BrpCH3, which is expected because the cyano is a stronger electron-withdrawing group than bromine. Consequently, the 1-Ring hydrogen atoms of m′CNpCH3 exhibit greater partial positive character; nonetheless, the 1-Rings for both m′CNpCH3 and m′BrpCH3 show C—H⋯π interactions, see discussion below. Additionally, the small and slightly positive region on Br1 (Fig. 4, right) hints toward a σ-hole and an opportunity for a halogen bond in m′BrpCH3. The Hirshfeld analyses below highlight the main intermolecular interactions found in m′CNpCH3 and m′BrpCH3 (Spackman & Jayatilaka, 2009); see the supporting information for fingerprint plots showing the percentage distribution of the intermolecular interactions represented by the dnorm surface in Fig. 5.
From a Hirshfeld analysis, the dnorm surfaces indicate close contacts (red regions) near H7, H8, H11, H17A, C7, C11, and N1 for m′CNpCH3 and H8, C11, and Br1 for m′BrpCH3. Upon closer inspection of these atoms, m′CNpCH3 and m′BrpCH3 contain multiple C—H⋯π interactions, which can be seen in Fig. 6 as red regions. Note that the following summary of short contacts between two atoms, which have distances less than the sum of their van der Waals (vdW) radii, references data found in Table 2 where non-rounded distances and errors can also be found. Notable hydrogen–carbon short contacts for m′CNpCH3 are C8—H8⋯C11iv (2.88 Å) and C11—H11⋯C7iii (2.82 Å). In comparison, similar short contacts for m′BrpCH3 are C8—H8⋯C11iii (2.80 Å) and C11—H11⋯C7ii (2.89 Å). m′CNpCH3 contains some notable C—H⋯N interactions, which can be seen in Fig. 7 as red regions. The hydrogen–nitrogen short contacts for m′CNpCH3 are C7—H7⋯N1ii (2.60 Å) and C17—H17A⋯N1i (2.62 Å). For the sake of comparison to m′CNpCH3, C7—H7⋯Br1v (3.24 Å) and C16—H16A⋯Br1i (3.10 Å) in m′BrpCH3, which can be seen in Fig. 7 as white regions, have distances that are greater than the sum of bromine and hydrogen vdW radii (3.05 Å). Nonetheless, m′BrpCH3 contains a Br⋯Br interaction, see the red region associated with Br1 in Fig. 7. This type I halogen bond exhibits a short contact for Br1⋯Br1iv of 3.5565 (5) Å (Cavallo et al., 2016).
For aromatic rings, π-stacking can exhibit multiple orientations, e.g. sandwich, parallel-displaced, and edge-to-face (Wheeler, 2011), arising largely from dispersion and/or electrostatic interactions. The C—H⋯π interactions of m′CNpCH3 and m′BrpCH3 resemble the edge-to-face orientation, which is also referred to as a T-shaped orientation. More specifically, the H8⋯3-Ring and H11⋯1-Ring interactions of m′CNpCH3 and m′BrpCH3 resemble a bent T-shaped orientation, or the so-called B-T1 orientation as defined by Dinadayalane & Leszczynski (2009). A computationally derived centroid-to-centroid distance for the B-T1 orientation is 4.63 Å (Dinadayalane & Leszczynski, 2009), which is close to the centroid distances for the 1-Ring⋯3-Ringiv of m′CNpCH3 (4.60 Å), the 1-Ring⋯3-Ringiii of m′BrpCH3 (4.52 Å), the 3-Ring⋯1-Ringiii of m′CNpCH3 (4.71 Å), and the 3-Ring⋯1-Ringii of m′BrpCH3 (4.90 Å). See Table 2 for non-rounded distances and errors.
Inspection of packing diagrams indicate that the m′CNpCH3 molecules form antiparallel sheets, Fig. 8. The interactions that contribute the most to this stacking are the C—H⋯π interactions (C8—H8⋯C11iv or 1-Ring⋯3-Ringiv and C11—H11⋯C7iii or 3-Ring⋯1-Ringiii) and C—H⋯N interactions (C17—H17A⋯N1i), Figs. 6 and 7. All of these short contacts are less than their respective sum of vdW radii and are expected to contribute to the packing structure. Packing diagrams for m′BrpCH3 also show antiparallel sheets, Fig. 8. Similar to m′CNpCH3, the C—H⋯π interactions (C8—H8⋯C11iii or 1-Ring⋯3-Ringiii and C11—H11⋯C7ii or 3-Ring⋯1-Ringii) are also contributors to this stacking arrangement. Both have strong interactions that contribute to the lateral arrangement of molecules in the packing diagrams. For m′CNpCH3 this interaction is the C7—H7⋯N1i interaction visualized in Fig. 7. For m′BrpCH3, the Br1⋯Br1iv interaction, or type 1 halogen bond, contributes to the lateral arrangement.
4. Database survey
A survey of the Cambridge Structural Database (CSD version 5.41, November 2019; Groom et al., 2016), which excluded substituted with additional rings, did not yield any mono-substituted cyanochalcone structures. The only disubstituted cyanochalcones found contained a pCN group on the 3-Ring; 4-cyano-2′-fluorochalcone [Bo19p] (LERXOW; P; Braun et al., 2006a) and 4-cyano-4′-diethylaminochalcone [Qp19p] (NAWCEU; P21/c; Braun et al., 2006b). Two of the CN structures, NAWCEU and m′CNpCH3 [Sm6p], share the same P21/c, while LERXOW belongs to the P m′CNpCH3 is the first cyanochalcone with a meta-cyano substituent and is the first disubstituted cyano-methyl-chalcone structure. Analysis of the close contacts for LERXOW and NAWCEU reveals different interactions than for m′CNpCH3. Both structures display no strong interactions involving the cyano substituent, and instead both have strong interactions involving the carbonyl oxygen and the aromatic hydrogen atoms. LERXOW has a strong interaction between O1 and H3 and H11, while the oxygen interaction of note for NAWCEU is between O1 and H14. Additionally, C–H⋯π interactions have a lesser impact on the packing structure, as indicated by Hirshfeld analysis. More data are required to assess whether these differences are a function of meta versus para cyano substitution.
The same survey, again excluding molecules containing additional rings, showed multiple meta position of the 1-Ring, and two of which are disubstituted with a bromo and a methyl group. 3′-Bromochalcone [Dm-1] (CICLUW; P; Rosli et al., 2007) and m′BrpCH3 [Dm6p] belong to the same P. The two disubstituted most similar to m′BrpCH3, 4′-bromo-4-methylchalcone [Dp6p] (IZEFOI; P21/c; Wang et al., 2004) and 3-bromo-4′-methylchalcone [Fp4m] (IGAPAI; P; Li et al., 2008), are the only disubstituted Br/CH3 Of the two disubstituted only IGAPAI shares the same as m′BrpCH3, and IGAPAI also exhibits a type I halogen bond (Cavallo et al., 2016), similar to m′BrpCH3. IZEFOI does display C—H⋯π interactions, but these support a parallel arrangement, with the 3-Ring forming close contacts with the 3-Ring of a neighboring molecule, as opposed to the antiparallel nature of the C—H⋯π interactions for m′BrpCH3. m′BrpCH3 is the first methyl-substituted chalcone structure with an m′Br atom. Note that the codes Bo19p, Dm-1, Dm6p, Dp6p, Fp4m, Qp19p, and Sm6p are internal codes tied to a large, long-term project.
containing a bromo substitution, nine of which are substituted in the5. Synthesis and crystallization
Synthesis. The preparations of m′CNpCH3 [Sm6p] (Merchant et al., 1965) and m′BrpCH3 [Dm6p] have previously been reported (Budakoti et al., 2008; Ellsworth et al., 2008; Rangarajan et al., 2016; Soni & Patel, 2017; Zhang et al., 2017). Ethanol (1.5 mL, 95%) and a magnetic stir bar were added to two separate Biotage microwave vials (2–5 mL); one contained 4-methylbenzaldehyde (3 mmol) and the other contained 3′-acetophenone (3 mmol). Each vial was heated gently over a hot plate until complete dissolution and then cooled to room temperature; solids may precipitate upon cooling depending on the solubility of the starting material. Once cooled, NaOH (aq) (0.4 mL, 50% by wgt) was added to a benzaldehyde–acetophenone mixture. The resulting reaction mixture was vigorously agitated with a microspatula until a slurry formed. Water (2 mL) was added to the vial and its contents were agitated. The vial was capped, centrifuged for one minute, and decanted. This trituration was repeated three times. Methanol (2 mL) was added to the vessel and sealed; the microwave-safe vials are safe at high pressures, up to 30 bar. Over a hot plate while stirring, the contents were heated until complete dissolution. Once removed from the heat, the vial was allowed to cool, and crystal growth was observed. Crystals were isolated and dried using vacuum filtration. 1H NMR (400 MHz, CDCl3, referenced to TMS): δ (ppm) for m′BrpCH3 are 8.13 (t, 1H, J = 1.7 Hz), 7.93 (ddd, 1H, J = 7.8, 1.4, 1.0 Hz), 7.80 (d, 1H, J = 15.6 Hz), 7.70 (ddd, 1H, J = 8.0, 2.0, 1.0 Hz), 7.55 (d, 2H, J = 8.1 Hz), 7.40 (m, 2H), 7.23 (d, 2H, J = 8.0 Hz), 2.40 (s, 3H); and for m′CNpCH3 are 8.28 (t, 1H, J = 1.2 Hz), 8.23 (ddd, 1H, J = 7.9, 1,7, 1.2 Hz), 7.84 (m, 2H), 7.64 (t, 1H, J = 7.9 Hz), 7.56 (d, 2H, J = 8.1 Hz), 7.43 (d, 1H, J = 15.6 Hz), 7.25 (d, 2H, J = 8.5 Hz), 2.41 (s, 3H). 13C NMR (100 MHz, CDCl3, referenced to solvent, 77.16 ppm): δ (ppm) for m′BrpCH3 are 189.25, 145.97, 141.63, 140.29, 135.63, 132.01, 131.60, 130.32, 129.91, 128.77, 127.10, 123.07, 120.51, 21.72; and for m′CNpCH3 are 188.48, 146.82, 142.01, 139.29, 135.65, 132.53, 132.20, 131.73, 129.98, 129.77, 128.87, 119.83, 118.21, 113.20, 21.74.
Crystallization. m′BrpCH3 and m′CNpCH3 were crystallized through slow cooling in a Dewar hemispherical low-form flask. Chalcone (20 mg), methanol (0.5 mL), and a magnetic spin vane were added to a conical Biotage microwave vial (0.5–2 mL) and sealed. The tube was placed in boiling water for 1–5 minutes until complete dissolution. While the tube was submerged, two Dewar hemispherical low-form flasks were filled with boiling water and allowed to sit. When the chalcone had nearly dissolved, the Dewar flasks were emptied, and one was placed in a Styrofoam cooler. The Biotage microwave vial was removed from boiling water and placed in the Dewar inside the cooler. The Dewar was filled with boiling water to completely submerge the microwave vial. A round silicone gasket was placed to cover the rim of this Dewar flask before inverting the second Dewar and placing it on top to create a chamber. The cooler was closed with a Styrofoam lid on a low-vibration table in a temperature-regulated room. After 24 h, the vials were removed from the Dewar and crystals were collected using vacuum filtration.
6. Refinement
Crystal data, data collection and structure . The data for each chalcone derivative was measured at 100 K on a Bruker Photon II D8 Venture diffractometer equipped with both IμS-Cu and IμS-Mo microfocus X-ray sources. The Cu Kα (λ = 1.54178 Å) source was used for all crystallographic investigations. Data sets were corrected for Lorentz and polarization effects as well as absorption. The criterion for observed reflections is I > 2σ(I). Lattice parameters were determined from least-squares analysis of reflection data. Empirical absorption corrections were applied using SADABS (Krause et al., 2015). Structures were solved by and refined by full-matrix least-squares analysis on F2 using X-SEED equipped with SHELXT (Barbour, 2001 and Sheldrick, 2015a). All non-hydrogen atoms were refined anisotropically by full-matrix least-squares on F2 using the SHELXL program (Sheldrick, 2015b). H atoms (for OH and NH) were located in a difference-Fourier synthesis and refined isotropically with independent O/N—H distances or restrained to 0.85 (2) Å. The remaining H atoms were included in idealized geometric positions with Uiso(H) = 1.2Ueq(parent atom) or 1.5Ueq(C-methyl).
details are summarized in Table 3
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Unit cells were visualized with Mercury 2020.1 (Macrae et al., 2020), Hirshfeld analyses were executed with Crystal Explorer 17.5 (Turner et al., 2017), while distance/angle measurements as well as ORTEP images were captured using OLEX2 (Dolomanov et al., 2009).
Supporting information
https://doi.org/10.1107/S2056989020011135/tx2030sup1.cif
contains datablocks I, II. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020011135/tx2030Isup2.hkl
Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S2056989020011135/tx2030IIsup3.hkl
Hirshfeld fingerprint plots. DOI: https://doi.org/10.1107/S2056989020011135/tx2030sup4.pdf
Supporting information file. DOI: https://doi.org/10.1107/S2056989020011135/tx2030Isup5.cml
Supporting information file. DOI: https://doi.org/10.1107/S2056989020011135/tx2030IIsup6.cml
For both structures, data collection: APEX3 (Bruker, 2018); cell
SAINT (Bruker, 2017); data reduction: SAINT (Bruker, 2017); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: X-SEED (Barbour, 2001).C17H13NO | F(000) = 520 |
Mr = 247.28 | Dx = 1.296 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54178 Å |
a = 7.2986 (1) Å | Cell parameters from 7537 reflections |
b = 5.8504 (1) Å | θ = 3.0–72.1° |
c = 29.7783 (5) Å | µ = 0.64 mm−1 |
β = 94.525 (1)° | T = 100 K |
V = 1267.56 (4) Å3 | Transparent plate, colourless |
Z = 4 | 0.35 × 0.21 × 0.09 mm |
Bruker D8 Venture diffractometer | 2494 independent reflections |
Radiation source: Microsource IuS Incoatec 3.0 | 2213 reflections with I > 2σ(I) |
Double Bounce Multilayer Mirrors monochromator | Rint = 0.028 |
Detector resolution: 7.9 pixels mm-1 | θmax = 72.1°, θmin = 3.0° |
φ and ω scans | h = −9→8 |
Absorption correction: multi-scan (SADABS; Krause et al., 2015) | k = −7→7 |
Tmin = 0.676, Tmax = 0.754 | l = −36→36 |
13801 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.033 | H-atom parameters constrained |
wR(F2) = 0.087 | w = 1/[σ2(Fo2) + (0.045P)2 + 0.4265P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
2494 reflections | Δρmax = 0.21 e Å−3 |
173 parameters | Δρmin = −0.18 e Å−3 |
0 restraints |
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. All nonhydrogen atoms were located in a single difference Fourier electron density map and refined using anisotropic displacement parameters. All C-H hydrogen atoms were placed in calculated positions with Uiso = 1.2xUeqiv of the connected C atoms (1.5xUeqiv for methyl groups). |
x | y | z | Uiso*/Ueq | ||
O1 | 0.22192 (11) | 0.72690 (13) | 0.47783 (2) | 0.02168 (19) | |
N1 | 0.13188 (15) | 0.75910 (19) | 0.27529 (3) | 0.0286 (2) | |
C1 | 0.21471 (14) | 0.52052 (18) | 0.47083 (3) | 0.0165 (2) | |
C2 | 0.26906 (14) | 0.35011 (18) | 0.50599 (3) | 0.0174 (2) | |
H2 | 0.282576 | 0.194303 | 0.497894 | 0.021* | |
C3 | 0.29943 (14) | 0.41308 (18) | 0.54913 (3) | 0.0160 (2) | |
H3 | 0.282067 | 0.570173 | 0.555670 | 0.019* | |
C4 | 0.14995 (14) | 0.43210 (18) | 0.42488 (3) | 0.0159 (2) | |
C5 | 0.16826 (14) | 0.57332 (18) | 0.38769 (3) | 0.0163 (2) | |
H5 | 0.221501 | 0.720872 | 0.391577 | 0.020* | |
C6 | 0.10757 (14) | 0.49562 (19) | 0.34474 (3) | 0.0171 (2) | |
C7 | 0.02732 (14) | 0.27968 (19) | 0.33848 (4) | 0.0187 (2) | |
H7 | −0.013000 | 0.227830 | 0.309115 | 0.022* | |
C8 | 0.00746 (14) | 0.14251 (19) | 0.37570 (4) | 0.0189 (2) | |
H8 | −0.049184 | −0.003134 | 0.371874 | 0.023* | |
C9 | 0.06980 (14) | 0.21624 (18) | 0.41866 (4) | 0.0176 (2) | |
H9 | 0.057822 | 0.119396 | 0.443864 | 0.021* | |
C10 | 0.35662 (14) | 0.26495 (18) | 0.58726 (3) | 0.0152 (2) | |
C11 | 0.33577 (14) | 0.34331 (19) | 0.63106 (3) | 0.0173 (2) | |
H11 | 0.287002 | 0.491628 | 0.635291 | 0.021* | |
C12 | 0.38509 (15) | 0.20805 (19) | 0.66834 (3) | 0.0186 (2) | |
H12 | 0.366765 | 0.263493 | 0.697639 | 0.022* | |
C13 | 0.46133 (14) | −0.00854 (19) | 0.66336 (3) | 0.0173 (2) | |
C14 | 0.48597 (14) | −0.08447 (18) | 0.61969 (4) | 0.0171 (2) | |
H14 | 0.540026 | −0.229971 | 0.615618 | 0.021* | |
C15 | 0.43333 (14) | 0.04771 (18) | 0.58221 (3) | 0.0164 (2) | |
H15 | 0.449373 | −0.009384 | 0.552915 | 0.020* | |
C16 | 0.12291 (15) | 0.6427 (2) | 0.30610 (4) | 0.0206 (2) | |
C17 | 0.51598 (16) | −0.1542 (2) | 0.70393 (4) | 0.0227 (2) | |
H17A | 0.627558 | −0.091602 | 0.719826 | 0.034* | |
H17B | 0.539551 | −0.310760 | 0.694210 | 0.034* | |
H17C | 0.416382 | −0.154959 | 0.724164 | 0.034* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0290 (4) | 0.0159 (4) | 0.0197 (4) | 0.0010 (3) | −0.0009 (3) | −0.0006 (3) |
N1 | 0.0352 (6) | 0.0302 (6) | 0.0197 (5) | −0.0055 (5) | −0.0016 (4) | 0.0035 (4) |
C1 | 0.0144 (5) | 0.0176 (5) | 0.0178 (5) | 0.0007 (4) | 0.0024 (4) | −0.0003 (4) |
C2 | 0.0185 (5) | 0.0157 (5) | 0.0179 (5) | 0.0019 (4) | 0.0012 (4) | 0.0001 (4) |
C3 | 0.0137 (5) | 0.0149 (5) | 0.0196 (5) | −0.0004 (4) | 0.0019 (4) | −0.0003 (4) |
C4 | 0.0139 (5) | 0.0163 (5) | 0.0174 (5) | 0.0035 (4) | 0.0011 (4) | 0.0000 (4) |
C5 | 0.0146 (5) | 0.0149 (5) | 0.0192 (5) | 0.0016 (4) | 0.0007 (4) | 0.0000 (4) |
C6 | 0.0155 (5) | 0.0186 (5) | 0.0172 (5) | 0.0031 (4) | 0.0010 (4) | 0.0015 (4) |
C7 | 0.0171 (5) | 0.0205 (5) | 0.0182 (5) | 0.0033 (4) | −0.0013 (4) | −0.0039 (4) |
C8 | 0.0168 (5) | 0.0152 (5) | 0.0244 (5) | 0.0006 (4) | −0.0003 (4) | −0.0013 (4) |
C9 | 0.0164 (5) | 0.0162 (5) | 0.0202 (5) | 0.0022 (4) | 0.0014 (4) | 0.0023 (4) |
C10 | 0.0128 (5) | 0.0164 (5) | 0.0161 (5) | −0.0023 (4) | 0.0005 (4) | −0.0005 (4) |
C11 | 0.0167 (5) | 0.0156 (5) | 0.0195 (5) | −0.0010 (4) | 0.0018 (4) | −0.0023 (4) |
C12 | 0.0205 (5) | 0.0209 (5) | 0.0146 (5) | −0.0024 (4) | 0.0017 (4) | −0.0034 (4) |
C13 | 0.0160 (5) | 0.0193 (5) | 0.0164 (5) | −0.0036 (4) | −0.0004 (4) | 0.0015 (4) |
C14 | 0.0162 (5) | 0.0148 (5) | 0.0205 (5) | −0.0001 (4) | 0.0020 (4) | −0.0004 (4) |
C15 | 0.0158 (5) | 0.0185 (5) | 0.0150 (5) | −0.0010 (4) | 0.0021 (4) | −0.0014 (4) |
C16 | 0.0210 (5) | 0.0222 (6) | 0.0182 (5) | −0.0011 (4) | −0.0013 (4) | −0.0024 (5) |
C17 | 0.0260 (6) | 0.0230 (6) | 0.0188 (5) | −0.0008 (5) | −0.0001 (4) | 0.0039 (4) |
O1—C1 | 1.2257 (13) | C8—H8 | 0.9500 |
N1—C16 | 1.1487 (15) | C9—H9 | 0.9500 |
C1—C2 | 1.4771 (15) | C10—C15 | 1.4017 (15) |
C1—C4 | 1.5038 (14) | C10—C11 | 1.4021 (14) |
C2—C3 | 1.3380 (15) | C11—C12 | 1.3875 (15) |
C2—H2 | 0.9500 | C11—H11 | 0.9500 |
C3—C10 | 1.4629 (14) | C12—C13 | 1.3965 (16) |
C3—H3 | 0.9500 | C12—H12 | 0.9500 |
C4—C5 | 1.3966 (15) | C13—C14 | 1.3992 (15) |
C4—C9 | 1.3980 (15) | C13—C17 | 1.5062 (14) |
C5—C6 | 1.3961 (14) | C14—C15 | 1.3869 (15) |
C5—H5 | 0.9500 | C14—H14 | 0.9500 |
C6—C7 | 1.3988 (16) | C15—H15 | 0.9500 |
C6—C16 | 1.4482 (15) | C17—H17A | 0.9800 |
C7—C8 | 1.3852 (16) | C17—H17B | 0.9800 |
C7—H7 | 0.9500 | C17—H17C | 0.9800 |
C8—C9 | 1.3920 (15) | ||
O1—C1—C2 | 122.61 (10) | C4—C9—H9 | 119.8 |
O1—C1—C4 | 119.98 (9) | C15—C10—C11 | 118.03 (9) |
C2—C1—C4 | 117.41 (9) | C15—C10—C3 | 123.08 (9) |
C3—C2—C1 | 120.63 (10) | C11—C10—C3 | 118.89 (10) |
C3—C2—H2 | 119.7 | C12—C11—C10 | 121.16 (10) |
C1—C2—H2 | 119.7 | C12—C11—H11 | 119.4 |
C2—C3—C10 | 126.70 (10) | C10—C11—H11 | 119.4 |
C2—C3—H3 | 116.6 | C11—C12—C13 | 120.86 (10) |
C10—C3—H3 | 116.6 | C11—C12—H12 | 119.6 |
C5—C4—C9 | 119.63 (10) | C13—C12—H12 | 119.6 |
C5—C4—C1 | 118.38 (10) | C12—C13—C14 | 117.92 (9) |
C9—C4—C1 | 121.98 (9) | C12—C13—C17 | 120.70 (9) |
C6—C5—C4 | 119.38 (10) | C14—C13—C17 | 121.37 (10) |
C6—C5—H5 | 120.3 | C15—C14—C13 | 121.54 (10) |
C4—C5—H5 | 120.3 | C15—C14—H14 | 119.2 |
C5—C6—C7 | 121.03 (10) | C13—C14—H14 | 119.2 |
C5—C6—C16 | 119.71 (10) | C14—C15—C10 | 120.45 (10) |
C7—C6—C16 | 119.24 (9) | C14—C15—H15 | 119.8 |
C8—C7—C6 | 119.06 (10) | C10—C15—H15 | 119.8 |
C8—C7—H7 | 120.5 | N1—C16—C6 | 178.83 (12) |
C6—C7—H7 | 120.5 | C13—C17—H17A | 109.5 |
C7—C8—C9 | 120.57 (10) | C13—C17—H17B | 109.5 |
C7—C8—H8 | 119.7 | H17A—C17—H17B | 109.5 |
C9—C8—H8 | 119.7 | C13—C17—H17C | 109.5 |
C8—C9—C4 | 120.32 (10) | H17A—C17—H17C | 109.5 |
C8—C9—H9 | 119.8 | H17B—C17—H17C | 109.5 |
O1—C1—C2—C3 | 11.34 (17) | C5—C4—C9—C8 | −0.38 (15) |
C4—C1—C2—C3 | −169.15 (10) | C1—C4—C9—C8 | 178.43 (9) |
C1—C2—C3—C10 | −178.91 (9) | C2—C3—C10—C15 | 17.24 (17) |
O1—C1—C4—C5 | 24.95 (15) | C2—C3—C10—C11 | −163.34 (10) |
C2—C1—C4—C5 | −154.58 (10) | C15—C10—C11—C12 | −1.61 (15) |
O1—C1—C4—C9 | −153.88 (10) | C3—C10—C11—C12 | 178.95 (9) |
C2—C1—C4—C9 | 26.59 (14) | C10—C11—C12—C13 | 1.57 (16) |
C9—C4—C5—C6 | −0.58 (15) | C11—C12—C13—C14 | −0.10 (16) |
C1—C4—C5—C6 | −179.43 (9) | C11—C12—C13—C17 | 179.55 (10) |
C4—C5—C6—C7 | 0.60 (16) | C12—C13—C14—C15 | −1.32 (16) |
C4—C5—C6—C16 | 178.85 (9) | C17—C13—C14—C15 | 179.03 (10) |
C5—C6—C7—C8 | 0.34 (16) | C13—C14—C15—C10 | 1.28 (16) |
C16—C6—C7—C8 | −177.92 (10) | C11—C10—C15—C14 | 0.19 (15) |
C6—C7—C8—C9 | −1.30 (16) | C3—C10—C15—C14 | 179.62 (10) |
C7—C8—C9—C4 | 1.34 (16) |
C16H13BrO | Z = 2 |
Mr = 301.17 | F(000) = 304 |
Triclinic, P1 | Dx = 1.578 Mg m−3 |
a = 5.9282 (6) Å | Cu Kα radiation, λ = 1.54178 Å |
b = 7.3614 (8) Å | Cell parameters from 1318 reflections |
c = 14.6747 (16) Å | θ = 6.0–71.7° |
α = 88.532 (3)° | µ = 4.28 mm−1 |
β = 82.199 (3)° | T = 100 K |
γ = 87.457 (3)° | Transparent plate, colorless |
V = 633.73 (12) Å3 | 0.39 × 0.25 × 0.11 mm |
Bruker D8 Venture diffractometer | 2461 independent reflections |
Radiation source: Microsource IuS Incoatec 3.0 | 2440 reflections with I > 2σ(I) |
Double Bounce Multilayer Mirrors monochromator | Rint = 0.023 |
Detector resolution: 7.9 pixels mm-1 | θmax = 72.2°, θmin = 3.0° |
φ and ω scans | h = −6→7 |
Absorption correction: multi-scan (SADABS; Krause et al., 2015) | k = −9→9 |
Tmin = 0.531, Tmax = 0.754 | l = −18→18 |
8397 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.026 | H-atom parameters constrained |
wR(F2) = 0.065 | w = 1/[σ2(Fo2) + (0.0313P)2 + 0.5783P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max = 0.001 |
2461 reflections | Δρmax = 0.63 e Å−3 |
164 parameters | Δρmin = −0.40 e Å−3 |
0 restraints |
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. All nonhydrogen atoms were located in a single difference Fourier electron density map and refined using anisotropic displacement parameters. All C-H hydrogen atoms were placed in calculated positions with Uiso = 1.2xUeqiv of the connected C atoms (1.5xUeqiv for methyl groups). |
x | y | z | Uiso*/Ueq | ||
Br1 | 0.80035 (3) | 0.89029 (3) | 0.08237 (2) | 0.02192 (9) | |
O1 | 0.7329 (2) | 0.7890 (2) | 0.45698 (9) | 0.0223 (3) | |
C1 | 0.5354 (3) | 0.7917 (2) | 0.44225 (13) | 0.0170 (4) | |
C2 | 0.3466 (3) | 0.7319 (3) | 0.51279 (13) | 0.0192 (4) | |
H2 | 0.199245 | 0.718770 | 0.495759 | 0.023* | |
C3 | 0.3817 (3) | 0.6965 (2) | 0.59951 (13) | 0.0186 (4) | |
H3 | 0.530796 | 0.713033 | 0.613915 | 0.022* | |
C4 | 0.4726 (3) | 0.8590 (2) | 0.35130 (13) | 0.0155 (3) | |
C5 | 0.6366 (3) | 0.8439 (2) | 0.27330 (13) | 0.0161 (3) | |
H5 | 0.783980 | 0.791310 | 0.277957 | 0.019* | |
C6 | 0.5803 (3) | 0.9069 (2) | 0.18959 (12) | 0.0167 (3) | |
C7 | 0.3658 (3) | 0.9867 (2) | 0.18070 (13) | 0.0189 (4) | |
H7 | 0.330243 | 1.029208 | 0.122449 | 0.023* | |
C8 | 0.2067 (3) | 1.0024 (2) | 0.25840 (14) | 0.0192 (4) | |
H8 | 0.061052 | 1.058189 | 0.253582 | 0.023* | |
C9 | 0.2567 (3) | 0.9378 (2) | 0.34359 (13) | 0.0175 (4) | |
H9 | 0.144730 | 0.947060 | 0.396286 | 0.021* | |
C10 | 0.2121 (3) | 0.6346 (2) | 0.67464 (13) | 0.0180 (4) | |
C11 | 0.2535 (3) | 0.6525 (2) | 0.76554 (14) | 0.0197 (4) | |
H11 | 0.393474 | 0.699115 | 0.777189 | 0.024* | |
C12 | 0.0940 (3) | 0.6036 (3) | 0.83870 (13) | 0.0204 (4) | |
H12 | 0.124142 | 0.620360 | 0.899810 | 0.025* | |
C13 | −0.1104 (3) | 0.5301 (2) | 0.82409 (13) | 0.0188 (4) | |
C14 | −0.1492 (3) | 0.5068 (2) | 0.73322 (13) | 0.0191 (4) | |
H14 | −0.285712 | 0.453991 | 0.721786 | 0.023* | |
C15 | 0.0076 (3) | 0.5594 (3) | 0.65972 (13) | 0.0195 (4) | |
H15 | −0.023652 | 0.544247 | 0.598635 | 0.023* | |
C16 | −0.2846 (4) | 0.4761 (3) | 0.90371 (14) | 0.0243 (4) | |
H16A | −0.238535 | 0.357702 | 0.928866 | 0.036* | |
H16B | −0.433393 | 0.467934 | 0.882360 | 0.036* | |
H16C | −0.295102 | 0.567581 | 0.951623 | 0.036* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.02062 (13) | 0.02741 (13) | 0.01669 (12) | −0.00258 (8) | 0.00161 (8) | 0.00044 (8) |
O1 | 0.0152 (7) | 0.0321 (7) | 0.0196 (7) | −0.0023 (5) | −0.0024 (5) | 0.0007 (5) |
C1 | 0.0174 (9) | 0.0142 (8) | 0.0194 (9) | −0.0018 (7) | −0.0019 (7) | −0.0021 (6) |
C2 | 0.0175 (9) | 0.0191 (9) | 0.0206 (9) | −0.0019 (7) | −0.0008 (7) | −0.0013 (7) |
C3 | 0.0176 (9) | 0.0142 (8) | 0.0237 (9) | 0.0005 (7) | −0.0015 (7) | −0.0026 (7) |
C4 | 0.0150 (8) | 0.0131 (8) | 0.0188 (9) | −0.0030 (6) | −0.0025 (7) | −0.0012 (6) |
C5 | 0.0136 (8) | 0.0143 (8) | 0.0205 (9) | −0.0026 (6) | −0.0024 (7) | −0.0016 (7) |
C6 | 0.0163 (9) | 0.0167 (8) | 0.0168 (8) | −0.0043 (7) | 0.0005 (7) | −0.0012 (6) |
C7 | 0.0198 (9) | 0.0174 (8) | 0.0208 (9) | −0.0042 (7) | −0.0070 (7) | 0.0020 (7) |
C8 | 0.0140 (9) | 0.0167 (8) | 0.0275 (10) | −0.0003 (7) | −0.0048 (7) | −0.0008 (7) |
C9 | 0.0147 (9) | 0.0157 (8) | 0.0215 (9) | −0.0018 (7) | 0.0001 (7) | −0.0021 (7) |
C10 | 0.0183 (9) | 0.0148 (8) | 0.0209 (9) | 0.0002 (7) | −0.0026 (7) | 0.0011 (7) |
C11 | 0.0196 (9) | 0.0155 (8) | 0.0259 (10) | −0.0007 (7) | −0.0099 (8) | 0.0010 (7) |
C12 | 0.0245 (10) | 0.0175 (9) | 0.0207 (9) | 0.0020 (7) | −0.0092 (8) | 0.0001 (7) |
C13 | 0.0206 (9) | 0.0142 (8) | 0.0218 (9) | 0.0030 (7) | −0.0045 (7) | 0.0000 (7) |
C14 | 0.0187 (9) | 0.0167 (8) | 0.0230 (9) | −0.0025 (7) | −0.0058 (7) | −0.0003 (7) |
C15 | 0.0217 (10) | 0.0189 (9) | 0.0189 (9) | −0.0027 (7) | −0.0054 (7) | −0.0012 (7) |
C16 | 0.0244 (10) | 0.0272 (10) | 0.0211 (9) | 0.0001 (8) | −0.0027 (8) | −0.0006 (8) |
Br1—C6 | 1.9053 (18) | C8—H8 | 0.9500 |
O1—C1 | 1.219 (2) | C9—H9 | 0.9500 |
C1—C2 | 1.491 (3) | C10—C11 | 1.399 (3) |
C1—C4 | 1.500 (3) | C10—C15 | 1.401 (3) |
C2—C3 | 1.334 (3) | C11—C12 | 1.382 (3) |
C2—H2 | 0.9500 | C11—H11 | 0.9500 |
C3—C10 | 1.465 (3) | C12—C13 | 1.393 (3) |
C3—H3 | 0.9500 | C12—H12 | 0.9500 |
C4—C9 | 1.399 (3) | C13—C14 | 1.400 (3) |
C4—C5 | 1.401 (3) | C13—C16 | 1.508 (3) |
C5—C6 | 1.380 (3) | C14—C15 | 1.384 (3) |
C5—H5 | 0.9500 | C14—H14 | 0.9500 |
C6—C7 | 1.398 (3) | C15—H15 | 0.9500 |
C7—C8 | 1.382 (3) | C16—H16A | 0.9800 |
C7—H7 | 0.9500 | C16—H16B | 0.9800 |
C8—C9 | 1.391 (3) | C16—H16C | 0.9800 |
O1—C1—C2 | 122.32 (17) | C4—C9—H9 | 120.2 |
O1—C1—C4 | 120.48 (17) | C11—C10—C15 | 118.05 (18) |
C2—C1—C4 | 117.20 (16) | C11—C10—C3 | 119.08 (17) |
C3—C2—C1 | 120.92 (17) | C15—C10—C3 | 122.87 (17) |
C3—C2—H2 | 119.5 | C12—C11—C10 | 121.11 (18) |
C1—C2—H2 | 119.5 | C12—C11—H11 | 119.4 |
C2—C3—C10 | 126.21 (18) | C10—C11—H11 | 119.4 |
C2—C3—H3 | 116.9 | C11—C12—C13 | 120.94 (18) |
C10—C3—H3 | 116.9 | C11—C12—H12 | 119.5 |
C9—C4—C5 | 120.03 (17) | C13—C12—H12 | 119.5 |
C9—C4—C1 | 121.39 (17) | C12—C13—C14 | 118.08 (18) |
C5—C4—C1 | 118.57 (16) | C12—C13—C16 | 121.12 (18) |
C6—C5—C4 | 118.80 (17) | C14—C13—C16 | 120.80 (18) |
C6—C5—H5 | 120.6 | C15—C14—C13 | 121.21 (18) |
C4—C5—H5 | 120.6 | C15—C14—H14 | 119.4 |
C5—C6—C7 | 121.94 (17) | C13—C14—H14 | 119.4 |
C5—C6—Br1 | 119.84 (14) | C14—C15—C10 | 120.57 (18) |
C7—C6—Br1 | 118.21 (14) | C14—C15—H15 | 119.7 |
C8—C7—C6 | 118.60 (17) | C10—C15—H15 | 119.7 |
C8—C7—H7 | 120.7 | C13—C16—H16A | 109.5 |
C6—C7—H7 | 120.7 | C13—C16—H16B | 109.5 |
C7—C8—C9 | 120.93 (17) | H16A—C16—H16B | 109.5 |
C7—C8—H8 | 119.5 | C13—C16—H16C | 109.5 |
C9—C8—H8 | 119.5 | H16A—C16—H16C | 109.5 |
C8—C9—C4 | 119.69 (17) | H16B—C16—H16C | 109.5 |
C8—C9—H9 | 120.2 | ||
O1—C1—C2—C3 | 9.4 (3) | C5—C4—C9—C8 | −0.6 (3) |
C4—C1—C2—C3 | −169.73 (17) | C1—C4—C9—C8 | 178.53 (16) |
C1—C2—C3—C10 | −179.08 (17) | C2—C3—C10—C11 | −161.99 (18) |
O1—C1—C4—C9 | −151.81 (18) | C2—C3—C10—C15 | 17.3 (3) |
C2—C1—C4—C9 | 27.3 (2) | C15—C10—C11—C12 | −2.3 (3) |
O1—C1—C4—C5 | 27.4 (3) | C3—C10—C11—C12 | 177.07 (16) |
C2—C1—C4—C5 | −153.51 (16) | C10—C11—C12—C13 | 1.8 (3) |
C9—C4—C5—C6 | −0.4 (3) | C11—C12—C13—C14 | 0.2 (3) |
C1—C4—C5—C6 | −179.54 (16) | C11—C12—C13—C16 | 179.84 (17) |
C4—C5—C6—C7 | 0.7 (3) | C12—C13—C14—C15 | −1.6 (3) |
C4—C5—C6—Br1 | 179.46 (13) | C16—C13—C14—C15 | 178.69 (17) |
C5—C6—C7—C8 | 0.0 (3) | C13—C14—C15—C10 | 1.1 (3) |
Br1—C6—C7—C8 | −178.79 (13) | C11—C10—C15—C14 | 0.8 (3) |
C6—C7—C8—C9 | −1.0 (3) | C3—C10—C15—C14 | −178.51 (17) |
C7—C8—C9—C4 | 1.3 (3) |
The Φ1, Φ2, and Φ3 dihedrals are defined by C5—C4—C1—C2, C4—C1—C2—C3, and C2—C3—C10—C11, respectively. |
Chalcone | Φ1 | Φ2 | Φ3 | 1-Ring 3-Ring Twist | 1-Ring 3-Ring Fold |
m'CNpCH3 | -154.58 (10) | -169.15 (10) | -163.34 (10) | 49.11 (4) | 0.67 (4) |
m'BrpCH3 | -153.51 (16) | -169.73 (17) | -161.99 (18) | 49.15 (6) | 1.55 (6) |
Distances to the 1-Ring and 3-Ring reflect the distances to the centroids of those rings. The sums of the van der Waals radii (Å) for hydrogen plus carbon, nitrogen, or bromine are 2.9, 2.75, and 3.05, respectively, while the sum for bromine plus bromine is 3.7. The symmetry codes apply to those molecules interacting with the asymmetric unit. Estimated standard deviations are listed in parentheses. |
m'CNpCH3 | Distance | m'BrpCH3 | Distance |
C8—H8···C11iv | 2.8835 (11) | C8—H8···C11iii | 2.8019 (16) |
C8—H8···3-Ringiv | 2.7391 (4) | C8—H8···3-Ringiii | 2.709 (2) |
C11—H11···C7iii | 2.8187 (11) | C11—H11···C7ii | 2.8936 (17) |
C11—H11···1-Ringiii | 2.8866 (4) | C11—H11···1-Ringii | 3.061 (2) |
1-Ring···3-Ringiv | 4.6036 (6) | 1-Ring···3-Ringiii | 4.5176 (10) |
3-Ring···1-Ringiii | 4.7132 (6) | 3-Ring···1-Ringii | 4.8989 (11) |
C7—H7···N1ii | 2.5999 (9) | C7—H7···Br1v | 3.2379 (4) |
C17—H17A···N1i | 2.6168 (11) | C16—H16A···Br1i | 3.0962 (3) |
Br1···Br1iv | 3.5556 (5) |
Symmetry codes for m'CNpCH3: (i) 1 - x, 1 - y, 1 - z; (ii) -x, -1/2 + y, 1/2 - z; (iii) -x, 1 - y, 1 - z; (iv) -x, -y, 1 - z. Symmetry codes for m'BrpCH3: (i) 1 - x, 1 - y, 1 - z; (ii) 1 - x, 2 - y, 1 - z; (iii) -x, 2 - y, 1 - z; (iv) 2 - x, 2 - y, -z; (v) 1 - x, 2 - y, -z. |
Footnotes
‡Authors contributed equally.
Acknowledgements
The GU co-authors thank S. Economu, B. Hendricks, A. Hinz, J. Hazen, C. Sciammas, M. Plese, T. Cherry, A. Fijalka, and C. Mozo-Olazcon for their assistance, as well as the Howard Hughes Medical Institute for supporting equipment acquisition through its Undergraduate Science Education Program. Support also came from the Gonzaga Science Research Program as well as Gonzaga's Department of Chemistry and Biochemistry.
Funding information
Funding for this research was provided by: EPSRC (grant No. EP/L015544/1 to C. L. Hall; grant No. EP/L016648/1 to V. Hamilton); European Union's Horizon 2020 Research and Innovation Programme (grant No. 736899); funding for the Bruker Photon II D8 Venture diffractometer was provided by NSF-MRI #1827313.
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