research communications
Synthesis and
of methyl 3-(3-hydroxy-3-phenylprop-2-enoyl)benzoateaDepartment of Chemistry, Lomonosov Moscow State University, Lenin's Hills 1/3, Moscow 119991, Russian Federation, and bKurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskiy pr. 31, Moscow 119991, Russian Federation
*Correspondence e-mail: bezzubov@igic.ras.ru
The title compound, C17H14O4, was synthesized under mild conditions and characterized by various analytical techniques. Combined NMR and X-ray diffraction data show that the substance exists exclusively in the enol tautomeric form. An intramolecular ⋯O=C—C=C—OH⋯ hydrogen bond is present in the molecular structure. The analysis of the difference density map disclosed two adjacent positions of a disordered hydrogen atom taking part in this hydrogen bond, indicating the presence of two enol tautomers in the crystal. The enol molecules are assembled through numerous C—H⋯π and π–π as well as weak C(aryl)—H⋯O interactions, thus forming a dense crystal packing. The obtained substance was also studied by UV–Vis spectroscopy and cyclic voltammetry.
Keywords: crystal structure; β-diketone; hydrogen bond; tautomerism.
CCDC reference: 1838743
1. Chemical context
The high complexing ability via O-donor atoms and excellent optical properties of aromatic β-diketones make them practically irreplaceable in the creation of efficient emitters [as lanthanide or iridium(III) complexes] for application in OLEDs (organic light-emitting diodes; Eliseeva & Bünzli, 2010; Bünzli, 2015). In addition, β-diketone-based IrIII complexes have attracted particular attention as promising photosensitizers in dye-sensitized solar cells (Baranoff et al., 2010). Surprisingly, aromatic β-diketones functionalized by anchoring COOH groups have not been considered as a possible alternative to traditional anchoring 4,4′-dicarboxy-2,2′-bipyridine groups.
Herein we report on the β-diketone with formula C17H14O4, bearing a carboxymethyl group.
as well as optical and electrochemical properties of a non-symmetric aromatic2. Structural commentary
A 1H NMR study of the prepared β-diketone showed that it appears exclusively as an enol tautomer in solution (CDCl3). Single-crystal X-ray also confirmed unambiguously that the compound exists in the enol form in the solid state (Fig. 1a). In the molecular structure, an intramolecular resonance-assisted hydrogen bond (for related structures, see: Gilli et al., 2004) connects the two oxygen atoms of the keto–enol moiety with the O3⋯O4 distance as short as 2.4358 (10) Å (Table 1). The hydrogen atom involved in this interaction is disordered over two sites (H21 and H22) with almost equal occupancies. The virtual H⋯H distance of 0.625 (1) Å is a result of the simultaneous presence of two enol forms, O3—H⋯O4 and O3⋯H—O4, respectively, in an approximate 1:1 ratio in the crystal. The title molecule is almost planar with a variation of the dihedral angles between phenyl rings and the keto–enol plane between 5.65 (4) and 11.05 (4)°.
3. Supramolecular features
The enol molecules are assembled in a `head-to-tail' manner by several C—H⋯π [range 2.740 (15)–2.758 (15) Å] interactions (Table 1]) involving the phenyl H atoms and the centroids of the phenyl rings of adjacent molecules as well as by π–π contacts [range 3.422 (14)–3.531 (15) Å]. The resultant stacks are grafted together by weak C—H⋯O interactions (Desiraju & Steiner, 2001) between the aryl rings and the oxygen atoms of the keto–enol fragment with a C⋯O distance of 3.0837 (12) Å, forming a network structure (Table 1; Figs. 2 and 3).
4. Database survey
Although there have been numerous reports on crystal structures of various symmetric and non-symmetric β-diketones in the Cambridge Structural Database (Version 5.38, February 2018; Groom et al., 2016), only a few examples of aromatic β-diketones functionalized by COOH groups (or COOR) are well documented (Langer et al., 2006; Ishikawa & Ugai, 2013; Hui et al., 2010). In their molecular structures, the intramolecular resonance-assisted hydrogen bonds exhibit quite short O⋯O distances (2.39–2.55 Å; Bertolasi et al., 1991). The hydrogen atom located between these O atoms is either ordered or disordered by symmetry as in dibenzoylmethane and other symmetrical β-diketones (see, for example: Thomas et al., 2009; Andrews et al., 2014) or with unequal occupancies in the vast majority of non-symmetric (see, for instance: Aromí et al., 2002, Soldatov et al., 2003). In some cases, crystals contain two different enol molecules (O—H⋯O and O⋯H—O) with ordered H atoms (Mohamed et al., 2015; Zheng et al., 2009; Bertolasi et al., 1991).
5. Synthesis and crystallization
There are some synthetic difficulties encountered in preparation of carboxylated β-diketones according to the common Claisen condensation. Fortunately, the desired compounds can be obtained under mild conditions via an MgBr2·Et2O-assisted acylation of by benzotriazole of the corresponding diesters (Lim et al., 2007). The title compound was prepared as follows:
To a suspension of MgBr2·Et2O (0.73 g, 2.8 mmol) in dry CH2Cl2 (16 ml), acetophenone (0.35 ml, 3.0 mmol) was added and the mixture was sonicated for a minute. N,N-Diisopropylethylamine (0.52 ml, 3.0 mmol) was added to the mixture and it was sonicated for a minute. The resulted suspension was added quickly to a solution of the methyl ester of isophtalic acid benzotriazole amide (1.15 g, 4.0 mmol) in dry CH2Cl2 (16 ml) and the mixture was stirred at 293 K for 34 h. The reaction mixture was treated by a 2 M HCl solution (40 ml) and stirred vigorously for 1 h. The organic layer was separated and the aqueous layer extracted with CH2Cl2 (3 × 20 ml). The combined organic extracts were washed with water (1 × 20 ml) and brine (1 × 20 ml) and filtrated through paper followed by evaporation of the solvent. The resulting oil was crystallized from CH3OH solution at 255 K to give a light-yellow powder, which was purified by (SiO2, CHCl3/hexane 1/3 v/v) and dried in vacuo. Yield 457 mg (54%). Single crystals suitable for X-ray analysis were grown by slow evaporation of the solvent from a solution of the substance in chloroform.
Analysis: calculated for C17H14O4: C, 72.33; H, 5.00. Found: C, 72.28; H, 5.04.
1H NMR (CDCl3, ppm, 400 MHz): δ 3.99 (s, 3H, CH3), 6.92 (s, 1H, C–H), 7.51 (t, J = 7.5 Hz, 2H, Ar–H), 7.57–7.62 (m, 2H, Ar–H), 8.02 (d, J = 7.4 Hz, 2H, Ar–H), 8.22 (t, J = 7.8 Hz, 2H, Ar–H), 8.63 (s, 1H, Ar–H). See supplementary Fig. S1.
13C NMR (CDCl3, ppm, 100 MHz): δ 51.97, 92.81, 126.85, 127.78, 128.29, 128.50, 130.29, 130.96, 132.27, 132.74, 134.82, 135.45, 165.88, 183.99, 185.71. See supplementary Fig. S2.
UV–Vis (CH2Cl2): λmax = 344 nm (∊max = 32000 cm−1 M−1). See supplementary Fig. S3.
Redox potentials (Ar-saturated CH3CN with 0.01 M (n-Bu4N)ClO4 at scan rate of 25 mV s−1, ferrocene as external standard): Eox1 = 1.15, Eox2 = 1.53 V vs See supplementary Fig. S4.
6. Refinement
Crystal data, data collection and structure . All hydrogen atoms were located from a difference-density map and refined freely. The disordered hydrogen atoms H21 and H22 were clearly discernible from a difference-density map (Fig. 1b). Their occupancies refined to a ratio of 0.44 (7):0.56 (7) and with Uiso(H) = 1.5Ueq(O).
details are summarized in Table 2
|
Supporting information
CCDC reference: 1838743
https://doi.org/10.1107/S2056989018007259/wm5445sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989018007259/wm5445Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989018007259/wm5445Isup3.mol
^1^H-NMR spectrum of 3-(3-hydroxy-3-phenylprop-2-enoyl)benzoate. DOI: https://doi.org/10.1107/S2056989018007259/wm5445sup4.tif
^13^C-NMR spectrum of 3-(3-hydroxy-3-phenylprop-2-enoyl)benzoate. DOI: https://doi.org/10.1107/S2056989018007259/wm5445sup5.tif
UV-Vis spectrum of 3-(3-hydroxy-3-phenylprop-2-enoyl)benzoate in CH2Cl2 at 298 K. DOI: https://doi.org/10.1107/S2056989018007259/wm5445sup6.tif
Polarographic curves of 3-(3-hydroxy-3-phenylprop-2-enoyl)benzoate (CH3CN, 298 K). DOI: https://doi.org/10.1107/S2056989018007259/wm5445sup7.tif
Supporting information file. DOI: https://doi.org/10.1107/S2056989018007259/wm5445Isup8.cml
Data collection: APEX2 (Bruker, 2008); cell
SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009) and publCIF (Westrip, 2010).C17H14O4 | F(000) = 592 |
Mr = 282.28 | Dx = 1.367 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 7.8085 (10) Å | Cell parameters from 7383 reflections |
b = 10.5171 (14) Å | θ = 2.3–30.6° |
c = 17.124 (2) Å | µ = 0.10 mm−1 |
β = 102.711 (2)° | T = 150 K |
V = 1371.8 (3) Å3 | Block, colorless |
Z = 4 | 0.40 × 0.40 × 0.40 mm |
Bruker SMART APEXII diffractometer | 3488 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.019 |
ω scans | θmax = 30.0°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −10→10 |
k = −14→14 | |
16222 measured reflections | l = −24→23 |
4006 independent reflections |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.039 | Only H-atom coordinates refined |
wR(F2) = 0.114 | w = 1/[σ2(Fo2) + (0.0663P)2 + 0.2977P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
4006 reflections | Δρmax = 0.37 e Å−3 |
249 parameters | Δρmin = −0.22 e Å−3 |
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 | Occ. (<1) | |
O1 | −0.02289 (10) | 0.46985 (7) | 0.30296 (4) | 0.02697 (17) | |
O2 | −0.12474 (11) | 0.26937 (7) | 0.28859 (4) | 0.03277 (19) | |
O3 | 0.38132 (11) | 0.60581 (7) | 0.53783 (4) | 0.02964 (17) | |
H21 | 0.453 (8) | 0.656 (5) | 0.576 (4) | 0.044* | 0.44 (7) |
O4 | 0.57483 (11) | 0.70032 (7) | 0.65449 (4) | 0.02985 (18) | |
H22 | 0.514 (6) | 0.679 (3) | 0.602 (3) | 0.045* | 0.56 (7) |
C1 | −0.10630 (15) | 0.49402 (11) | 0.22003 (6) | 0.0300 (2) | |
C2 | −0.04506 (12) | 0.35314 (9) | 0.32993 (5) | 0.02290 (19) | |
C3 | 0.03831 (11) | 0.33830 (9) | 0.41682 (5) | 0.02148 (18) | |
C4 | −0.00756 (13) | 0.23323 (10) | 0.45741 (6) | 0.0255 (2) | |
C5 | 0.06741 (13) | 0.21642 (10) | 0.53842 (6) | 0.0272 (2) | |
C6 | 0.18868 (12) | 0.30374 (9) | 0.57898 (6) | 0.02360 (19) | |
C7 | 0.23487 (11) | 0.40975 (8) | 0.53865 (5) | 0.01984 (17) | |
C8 | 0.15825 (12) | 0.42696 (9) | 0.45750 (5) | 0.02100 (18) | |
C9 | 0.35890 (12) | 0.50819 (8) | 0.57990 (5) | 0.02039 (18) | |
C10 | 0.44676 (12) | 0.49939 (8) | 0.66080 (5) | 0.02051 (18) | |
C11 | 0.55464 (12) | 0.59996 (8) | 0.69575 (5) | 0.02053 (18) | |
C12 | 0.65178 (12) | 0.60014 (8) | 0.78042 (5) | 0.01982 (17) | |
C13 | 0.66742 (13) | 0.49140 (9) | 0.82826 (6) | 0.02281 (19) | |
C14 | 0.76486 (13) | 0.49531 (10) | 0.90678 (6) | 0.0260 (2) | |
C15 | 0.84439 (13) | 0.60801 (10) | 0.93823 (6) | 0.0264 (2) | |
C16 | 0.82857 (13) | 0.71666 (10) | 0.89115 (6) | 0.0266 (2) | |
C17 | 0.73336 (13) | 0.71309 (9) | 0.81247 (6) | 0.02385 (19) | |
H1 | −0.232 (2) | 0.4767 (14) | 0.2115 (9) | 0.039 (4)* | |
H2 | −0.085 (2) | 0.5860 (16) | 0.2101 (9) | 0.049 (4)* | |
H3 | −0.0581 (19) | 0.4386 (14) | 0.1844 (8) | 0.036 (3)* | |
H4 | −0.0921 (19) | 0.1711 (14) | 0.4287 (8) | 0.036 (3)* | |
H5 | 0.0327 (18) | 0.1435 (14) | 0.5681 (8) | 0.036 (3)* | |
H6 | 0.2389 (17) | 0.2880 (12) | 0.6355 (8) | 0.028 (3)* | |
H8 | 0.1889 (17) | 0.4998 (13) | 0.4304 (8) | 0.030 (3)* | |
H10 | 0.4322 (18) | 0.4265 (13) | 0.6917 (8) | 0.028 (3)* | |
H13 | 0.6130 (18) | 0.4132 (13) | 0.8092 (8) | 0.031 (3)* | |
H14 | 0.7750 (18) | 0.4169 (13) | 0.9395 (8) | 0.034 (3)* | |
H15 | 0.9105 (19) | 0.6135 (14) | 0.9943 (9) | 0.038 (4)* | |
H16 | 0.8836 (18) | 0.7951 (13) | 0.9107 (8) | 0.034 (3)* | |
H17 | 0.7219 (18) | 0.7909 (13) | 0.7788 (8) | 0.035 (3)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0310 (4) | 0.0272 (4) | 0.0201 (3) | −0.0005 (3) | −0.0001 (3) | −0.0007 (3) |
O2 | 0.0381 (4) | 0.0291 (4) | 0.0263 (4) | −0.0026 (3) | −0.0033 (3) | −0.0062 (3) |
O3 | 0.0382 (4) | 0.0254 (4) | 0.0218 (3) | −0.0056 (3) | −0.0012 (3) | 0.0055 (3) |
O4 | 0.0421 (4) | 0.0227 (3) | 0.0224 (3) | −0.0083 (3) | 0.0019 (3) | 0.0034 (3) |
C1 | 0.0315 (5) | 0.0358 (5) | 0.0202 (4) | 0.0036 (4) | 0.0003 (4) | 0.0018 (4) |
C2 | 0.0208 (4) | 0.0251 (4) | 0.0221 (4) | 0.0024 (3) | 0.0032 (3) | −0.0035 (3) |
C3 | 0.0194 (4) | 0.0241 (4) | 0.0205 (4) | 0.0027 (3) | 0.0035 (3) | −0.0031 (3) |
C4 | 0.0227 (4) | 0.0266 (5) | 0.0265 (5) | −0.0031 (3) | 0.0039 (3) | −0.0033 (4) |
C5 | 0.0270 (5) | 0.0273 (5) | 0.0269 (5) | −0.0045 (4) | 0.0055 (4) | 0.0016 (4) |
C6 | 0.0236 (4) | 0.0259 (4) | 0.0207 (4) | 0.0000 (3) | 0.0037 (3) | 0.0010 (3) |
C7 | 0.0186 (4) | 0.0211 (4) | 0.0193 (4) | 0.0018 (3) | 0.0030 (3) | −0.0015 (3) |
C8 | 0.0206 (4) | 0.0222 (4) | 0.0197 (4) | 0.0018 (3) | 0.0033 (3) | −0.0010 (3) |
C9 | 0.0204 (4) | 0.0204 (4) | 0.0200 (4) | 0.0017 (3) | 0.0035 (3) | −0.0004 (3) |
C10 | 0.0234 (4) | 0.0192 (4) | 0.0182 (4) | −0.0011 (3) | 0.0029 (3) | 0.0000 (3) |
C11 | 0.0227 (4) | 0.0196 (4) | 0.0194 (4) | 0.0003 (3) | 0.0049 (3) | −0.0007 (3) |
C12 | 0.0209 (4) | 0.0198 (4) | 0.0188 (4) | −0.0013 (3) | 0.0044 (3) | −0.0025 (3) |
C13 | 0.0240 (4) | 0.0201 (4) | 0.0229 (4) | −0.0024 (3) | 0.0022 (3) | −0.0004 (3) |
C14 | 0.0256 (5) | 0.0274 (5) | 0.0234 (4) | −0.0011 (3) | 0.0018 (4) | 0.0027 (3) |
C15 | 0.0248 (4) | 0.0320 (5) | 0.0208 (4) | −0.0019 (4) | 0.0015 (3) | −0.0037 (4) |
C16 | 0.0283 (5) | 0.0259 (5) | 0.0250 (4) | −0.0056 (4) | 0.0044 (4) | −0.0074 (4) |
C17 | 0.0283 (4) | 0.0202 (4) | 0.0233 (4) | −0.0031 (3) | 0.0062 (3) | −0.0028 (3) |
O1—C2 | 1.3361 (12) | C7—C8 | 1.3985 (12) |
O1—C1 | 1.4486 (12) | C7—C9 | 1.4858 (13) |
O2—C2 | 1.2127 (12) | C8—H8 | 0.953 (13) |
O3—C9 | 1.2881 (11) | C9—C10 | 1.4072 (12) |
O3—H21 | 0.92 (7) | C10—C11 | 1.4017 (12) |
O4—C11 | 1.2989 (11) | C10—H10 | 0.952 (13) |
O4—H22 | 0.94 (6) | C11—C12 | 1.4811 (12) |
C1—H1 | 0.980 (15) | C12—C13 | 1.3963 (13) |
C1—H2 | 1.003 (17) | C12—C17 | 1.4015 (12) |
C1—H3 | 0.977 (14) | C13—C14 | 1.3922 (13) |
C2—C3 | 1.4952 (12) | C13—H13 | 0.950 (14) |
C3—C4 | 1.3936 (14) | C14—C15 | 1.3904 (14) |
C3—C8 | 1.3945 (13) | C14—H14 | 0.990 (14) |
C4—C5 | 1.3932 (14) | C15—C16 | 1.3882 (14) |
C4—H4 | 0.981 (15) | C15—H15 | 0.986 (15) |
C5—C6 | 1.3903 (14) | C16—C17 | 1.3887 (13) |
C5—H5 | 0.990 (14) | C16—H16 | 0.956 (14) |
C6—C7 | 1.3999 (13) | C17—H17 | 0.993 (14) |
C6—H6 | 0.975 (13) | ||
C2—O1—C1 | 115.82 (8) | C7—C8—H8 | 119.3 (8) |
C9—O3—H21 | 101 (3) | O3—C9—C10 | 120.41 (8) |
C11—O4—H22 | 103 (2) | O3—C9—C7 | 116.37 (8) |
O1—C1—H1 | 109.5 (9) | C10—C9—C7 | 123.21 (8) |
O1—C1—H2 | 106.3 (9) | C11—C10—C9 | 119.19 (8) |
H1—C1—H2 | 110.7 (13) | C11—C10—H10 | 120.3 (8) |
O1—C1—H3 | 110.8 (8) | C9—C10—H10 | 120.5 (8) |
H1—C1—H3 | 108.0 (12) | O4—C11—C10 | 120.96 (8) |
H2—C1—H3 | 111.5 (12) | O4—C11—C12 | 115.73 (8) |
O2—C2—O1 | 123.67 (9) | C10—C11—C12 | 123.31 (8) |
O2—C2—C3 | 124.07 (9) | C13—C12—C17 | 119.40 (8) |
O1—C2—C3 | 112.25 (8) | C13—C12—C11 | 122.22 (8) |
C4—C3—C8 | 119.94 (8) | C17—C12—C11 | 118.37 (8) |
C4—C3—C2 | 118.40 (8) | C14—C13—C12 | 120.07 (8) |
C8—C3—C2 | 121.65 (8) | C14—C13—H13 | 117.7 (8) |
C5—C4—C3 | 119.97 (9) | C12—C13—H13 | 122.2 (8) |
C5—C4—H4 | 120.3 (8) | C15—C14—C13 | 120.12 (9) |
C3—C4—H4 | 119.8 (8) | C15—C14—H14 | 121.2 (8) |
C6—C5—C4 | 120.29 (9) | C13—C14—H14 | 118.7 (8) |
C6—C5—H5 | 119.2 (8) | C16—C15—C14 | 120.11 (9) |
C4—C5—H5 | 120.4 (8) | C16—C15—H15 | 118.5 (8) |
C5—C6—C7 | 120.05 (9) | C14—C15—H15 | 121.4 (8) |
C5—C6—H6 | 117.7 (8) | C15—C16—C17 | 120.09 (9) |
C7—C6—H6 | 122.2 (8) | C15—C16—H16 | 122.1 (8) |
C8—C7—C6 | 119.53 (8) | C17—C16—H16 | 117.8 (8) |
C8—C7—C9 | 118.28 (8) | C16—C17—C12 | 120.20 (9) |
C6—C7—C9 | 122.15 (8) | C16—C17—H17 | 120.1 (8) |
C3—C8—C7 | 120.22 (9) | C12—C17—H17 | 119.7 (8) |
C3—C8—H8 | 120.5 (8) |
Cg1 and Cg2 are the centroids of the C3–C8 and C12–C17 rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H21···O4 | 0.92 (7) | 1.54 (7) | 2.4358 (10) | 162 (4) |
O4—H22···O3 | 0.94 (6) | 1.55 (6) | 2.4358 (10) | 156 (3) |
C16—H16···O3i | 0.956 (14) | 2.417 (14) | 3.0837 (12) | 126.6 (11) |
C5—H5···Cg2ii | 0.990 (14) | 2.740 (15) | 3.525 (13) | 135.0 (8) |
C14—H14···Cg1iii | 0.990 (14) | 2.758 (15) | 3.968 (12) | 127.2 (8) |
Symmetry codes: (i) x+1/2, −y+3/2, z+1/2; (ii) −x+1/2, y−1/2, −z+3/2; (iii) x+1/2, −y+1/2, z+1/2. |
Acknowledgements
X-ray diffraction studies were performed at the Centre of Shared Equipment of IGIC RAS.
Funding information
Funding for this research was provided by: Russian Science Foundation (grant No. 17-73-10084).
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