research communications
E)-1-(4-ethoxyphenyl)-3-(4-fluorophenyl)prop-2-en-1-one
of (2aDepartment of Chemistry and Biochemistry, Shippensburg University, Shippensburg, PA 17257, USA, and bDepartment of Chemistry and Biochemistry, University of Southern Indiana, Evansville, IN 47712, USA
*Correspondence e-mail: ahpred@ship.edu
The title molecule, C17H15FO2, was synthesized by a Claisen–Schmidt condensation with 4-fluorobenzaldehyde and 4′-ethoxyacetophenone. The torsion angles between the 4-fluorophenyl ring and the alkene and the 4′-ethoxyphenyl ring and the 2-propen-1-one are −1.2 (4) and 1.2 (3)°, respectively; however, there is a larger torsion between the bonds comprising the 2-propen-1-one unit of 12.0 (4)°. The crystal packing is stabilized by intermolecular C—H⋯O/F hydrogen bonding, π–π stacking, and H–π interactions.
Keywords: crystal structure; chalcones; 4 and 4′ substitution; conjugated torsions.
CCDC reference: 2191384
1. Chemical context
et al., 2012). are also important starting materials for the synthesis of several pharmacologically interesting classes of such as isoxazoles, pyrazolines and pyrazoles (Kamal et al., 2019). In our research involving the synthesis of chalcone derivatives, we have synthesized and obtained an X-ray structure for the title compound, C17H15FO2, 2(E)-1-(4-ethoxyphenyl)-3-(4-fluorophenyl)-2-propen-1-one.
are a group of 1,3-diaryl-2-propen-1-one compounds that have been found to exhibit a wide variety of biological activity including anticancer, antimicrobial and anti-inflammatory properties (Sahu2. Structural commentary
This chalcone has aromatic rings with substitutions in the 4 position on both ends of the molecule, where the phenyl on the alkene is fluorinated, and the phenyl on the carbonyl contains an ethoxide (Fig. 1). Both phenyl rings are inclined towards the same side of the molecule thanks to the E geometry of the alkene. The compound is a heavily π-conjugated structure that is nearly planar. To measure the deviation from planarity, three torsion angles were examined. The angles involving the aromatic rings are nearly identical with little bend, where the torsion between the C8—C7 and C5—C4 bonds is −1.2 (4)°, and the torsion between the C8—C9 and C15—C10 bonds is 1.2 (3)°. However, the torsion angle of the chalcone between the O1—C9 and C7—C8 bonds is 12.0 (4)°, indicating a break in planarity. This single deviation causes a slight concave bend in the molecule. The title compound crystallized as a in the Pca21; thus, a clockwise and anticlockwise torsion of the chalcone are present with a 1:1 ratio in the unit cell.
There are several other from a CSD database search. If the halogen (–X) is maintained as a fluorine, the other substituent (–R) varies as either a methyl, hydroxyl, methoxy, or ethoxy group. Examination of the three torsion angles described above suggests that there is a trend in the degree of distortion from planarity, with an order of methyl, methoxy, ethoxy, to hydroxy by increasing planarity. While there are no direct examples that contain a halogen and an ethoxy, we felt comparison of our compound to the nearest chloro- and bromo-substituted compounds was warranted. The closest examples are a bromo/methoxy and a chloro/methoxy 4,4′ -substituted chalcone. Both cases are more distorted from planar than our fluoro/ethoxy chalcone. Lastly, we found a set of with an ethoxy substituent, where there are chlorine atoms in the 2 and 3 position of the respective phenyl ring. Both of these cases are more planar than our chalcone.
with a comparable 4 and 4′ set of substitutions that are summarized in Table 1
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3. Supramolecular features
2(E)-1-(4-Ethoxyphenyl)-3-(4-fluorophenyl)-2-propen-1-one crystallizes in the orthorhombic Pca21, with four molecules occupying one The molecules pack using hydrogen bonding, π–π stacking, and H–π interactions (Figs. 2, 3, 4). There are four hydrogen bonds (Table 2) that interconnect each molecule to three of its neighbors. The first is between the C3—H3 bond and an adjacent F1 atom, the second pairs the C5—H5 bond and a nearby O1 atom, and the final two involve the C14—H14 and C16—H16A bonds with a neighboring O1 atom. Given the extent of conjugated π bonds throughout this molecule, π–π stacking is present between adjacent molecules along the a axis [centroid–centroid distance = 4.240 Å], with alternating molecules related by the a glide plane of the Pca21 this orients these molecules such that adjacent molecules are mirror images of one another with opposing chalcone bond torsions. Lastly, there are H–π interactions present between H17A and the aromatic ring comprised of C1–C6, as well as between H17C and this same ring on another molecule, forming a chain of interactions that parallel the a axis.
In comparison to the other , our structure packs in a unique Pca21, where many others pack in Pbca or P. Common themes that appear among these structures include π–π stacking and hydrogen bonding to the carbonyl oxygen. However, it is interesting to note that the chloro/methoxy and bromo/methoxy analogs pack with π–π stacking where the molecules are mirror images from a plane that is colinear with the molecular mean plane, rather than images related to a plane that is orthogonal to the molecular mean plane as observed in our structure. Also, in the case where the –R substituent is a hydroxide, hydrogen bonding between the hydroxyl group and and the carbonyl oxygen dominates the packing.
described in Table 14. Database survey
A search of the Cambridge Structural Database (CSD, Version 5.43, update March 2022; Groom et al., 2016) for 4,4′-phenyl-substituted resulted in multiple hits. Most closely related to the title compound are three 4-fluorophenyl-substituted (E)-3-(4-fluorophenyl)-1-(4-methylphenyl)prop-2-en-1-one (Butcher et al., 2007), (E)-3-(4-fluorophenyl)-1-(4-hydroyxlphenyl)prop-2-en-1-one (Sobolev et al., 2022), (E)-3-(4-fluorophenyl)-1-(4-methoxylphenyl)prop-2-en-1-one (Zhao et al., 2009). Additionally, two 4′-methoxy-susbstituted compounds with 4-chloro or bromophenyl substitution were found, (E)-3-(4-chlorophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one (Whitwood et al., 2021) and (E)-3-(4-bromophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one (Wilhelm et al., 2022). Two 4′-ethoxy-substituted compounds were also found, (E)-3-(2-chlorophenyl)-1-(4-ethoxylphenyl)prop-2-en-1-one (Harshitha et al., 2018) and (E)-3-(3-chlorophenyl)-1-(4-ethoxylphenyl)prop-2-en-1-one (Harshitha et al., 2018). See Table 1 for relevant data from these structures.
5. Synthesis and crystallization
4-Fluorobenzaldehyde (3 mmol) and 4-ethoxyacetophenone (3 mmol) were mixed in 95% EtOH (2.5 mL). An aqueous solution of sodium hydroxide (0.3 mL, 15 mM) was added to the mixture dropwise. The mixture was allowed to stir at room temperature for 45 min. Cold distilled H2O (4 mL) was added and the mixture was cooled in an ice bath before isolating the solid product by vacuum filtration. The chalcone was purified by recrystallization with dichloromethane/hexane (4:1) to yield colorless crystals (77% yield). High-quality crystals for diffraction were grown from slow evaporation of 190 proof ethanol at room temperature, m.p. 392–394 K; IR (ATR) νmax 3067, 2936, 1653, 1596, 1572, 1504, 1157, 1033 cm−1; 1H NMR (400 MHz, CDCl3) δ 8.03 (d, J = 9.2 Hz, 2H), 7.76 (d, J = 15.6 Hz, 1H), 7.62 (dd, J = 5.5, 3.2 Hz, 2H), 7.46 (d, J = 15.6 Hz, 1H), 7.10 (t, J = 8.7 Hz, 2H), 6.79 (d, J = 8.7 Hz, 2H), 3.88 (s, 3H) ppm; 13C{1H} NMR (100MHz, CDCl3) δ 188.4, 163.5, 163.9 (d, 1JC–F = 252.1 Hz), 142.6, 131.3 (d, 4JC–F = 2.9 Hz), 131.0, 130.8, 130.2 (d, 3JC–F = 8.6 Hz), 121.5 (d, 6JC–F = 1.9 Hz), 116.0 (d, 2JC–F = 22.0 Hz), 113.8, 55.5 ppm. 1H NMR data have previously been reported (Liu et al., 2001).
6. Refinement
Crystal data, data collection and structure . Hydrogen atoms were generated using a riding model with geometric constraints and refined isotropically. Aromatic C—H distances are 0.95 Å, methylene C—H distances are 0.99 Å, and methyl C—H distances are 0.98 Å. Uiso(H) was 1.2 times Ueq(C) for aromatic and methylene hydrogen atoms, and 1.5 times Ueq(C) for methyl hydrogen atoms. There is minor whole molecule disorder visible in the residual peaks that was not refined since these peaks are rather small (< 0.26 e Å−3) and there was little improvement in the model.
details are summarized in Table 3
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Supporting information
CCDC reference: 2191384
https://doi.org/10.1107/S2056989022007423/zl5033sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989022007423/zl5033Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989022007423/zl5033Isup3.cml
Data collection: APEX4 (Bruker, 2021); cell
SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C17H15FO2 | Dx = 1.321 Mg m−3 |
Mr = 270.29 | Melting point = 119–121 K |
Orthorhombic, Pca21 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.1426 (4) Å | Cell parameters from 7611 reflections |
b = 17.0566 (9) Å | θ = 3.1–25.3° |
c = 11.1520 (6) Å | µ = 0.10 mm−1 |
V = 1358.63 (13) Å3 | T = 100 K |
Z = 4 | Block, colorless |
F(000) = 568 | 0.24 × 0.11 × 0.11 mm |
Bruker APEXII CCD diffractometer | 2365 reflections with I > 2σ(I) |
φ and ω scans | Rint = 0.061 |
Absorption correction: multi-scan (SADABS; Krause et al., 2015)' | θmax = 25.4°, θmin = 2.4° |
Tmin = 0.691, Tmax = 0.745 | h = −8→8 |
23454 measured reflections | k = −20→20 |
2438 independent reflections | l = −13→13 |
Refinement on F2 | Primary atom site location: dual |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.039 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.104 | H-atom parameters constrained |
S = 1.10 | w = 1/[σ2(Fo2) + (0.069P)2 + 0.1828P] where P = (Fo2 + 2Fc2)/3 |
2438 reflections | (Δ/σ)max < 0.001 |
182 parameters | Δρmax = 0.27 e Å−3 |
1 restraint | Δρmin = −0.17 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. |
Refinement. There is a minor disordered component visible in the residual peaks that is not refined, since there is little improvement in the model. |
x | y | z | Uiso*/Ueq | ||
F1 | 0.4847 (3) | 0.00701 (11) | 0.7445 (2) | 0.0476 (6) | |
O1 | 0.3123 (3) | 0.37163 (10) | 0.25635 (16) | 0.0242 (4) | |
O2 | 0.3964 (2) | 0.71755 (10) | 0.44972 (18) | 0.0227 (4) | |
C1 | 0.4610 (4) | 0.06802 (16) | 0.6686 (3) | 0.0326 (7) | |
C2 | 0.4545 (4) | 0.05380 (16) | 0.5477 (3) | 0.0301 (6) | |
H2 | 0.465389 | 0.001957 | 0.517328 | 0.036* | |
C3 | 0.4316 (4) | 0.11687 (16) | 0.4708 (3) | 0.0257 (6) | |
H3 | 0.426726 | 0.107993 | 0.386721 | 0.031* | |
C4 | 0.4154 (3) | 0.19357 (15) | 0.5148 (2) | 0.0205 (6) | |
C5 | 0.4225 (4) | 0.20530 (15) | 0.6394 (2) | 0.0220 (6) | |
H5 | 0.410714 | 0.256768 | 0.671075 | 0.026* | |
C6 | 0.4464 (4) | 0.14242 (17) | 0.7165 (3) | 0.0301 (6) | |
H6 | 0.452542 | 0.150326 | 0.800692 | 0.036* | |
C7 | 0.3907 (3) | 0.25841 (15) | 0.4307 (2) | 0.0208 (6) | |
H7 | 0.390057 | 0.244965 | 0.348020 | 0.025* | |
C8 | 0.3692 (4) | 0.33370 (14) | 0.4560 (2) | 0.0199 (5) | |
H8 | 0.369696 | 0.350200 | 0.537401 | 0.024* | |
C9 | 0.3442 (3) | 0.39260 (15) | 0.3600 (2) | 0.0185 (5) | |
C10 | 0.3596 (3) | 0.47712 (15) | 0.3897 (2) | 0.0179 (5) | |
C11 | 0.3348 (4) | 0.53263 (15) | 0.2981 (2) | 0.0211 (5) | |
H11 | 0.309041 | 0.515191 | 0.218899 | 0.025* | |
C12 | 0.3470 (3) | 0.61131 (15) | 0.3206 (2) | 0.0225 (6) | |
H12 | 0.328745 | 0.647740 | 0.257190 | 0.027* | |
C13 | 0.3862 (3) | 0.63855 (14) | 0.4366 (2) | 0.0195 (6) | |
C14 | 0.4132 (3) | 0.58453 (15) | 0.5286 (2) | 0.0192 (5) | |
H14 | 0.440382 | 0.602146 | 0.607528 | 0.023* | |
C15 | 0.4002 (4) | 0.50479 (15) | 0.5046 (2) | 0.0198 (5) | |
H15 | 0.419362 | 0.468300 | 0.567816 | 0.024* | |
C16 | 0.4192 (4) | 0.74662 (15) | 0.5705 (3) | 0.0236 (6) | |
H16A | 0.536921 | 0.726316 | 0.605590 | 0.028* | |
H16B | 0.313446 | 0.729185 | 0.621292 | 0.028* | |
C17 | 0.4247 (4) | 0.83493 (15) | 0.5646 (3) | 0.0264 (6) | |
H17A | 0.540214 | 0.851724 | 0.524786 | 0.040* | |
H17B | 0.420936 | 0.856464 | 0.646047 | 0.040* | |
H17C | 0.316396 | 0.853991 | 0.519179 | 0.040* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F1 | 0.0811 (15) | 0.0254 (9) | 0.0364 (10) | 0.0047 (9) | −0.0034 (10) | 0.0135 (8) |
O1 | 0.0317 (10) | 0.0254 (9) | 0.0156 (9) | −0.0012 (7) | 0.0005 (8) | −0.0020 (8) |
O2 | 0.0303 (10) | 0.0174 (9) | 0.0204 (10) | −0.0012 (7) | −0.0030 (8) | 0.0031 (7) |
C1 | 0.0432 (18) | 0.0207 (14) | 0.0338 (18) | 0.0018 (12) | −0.0004 (13) | 0.0099 (13) |
C2 | 0.0397 (15) | 0.0172 (12) | 0.0334 (16) | 0.0016 (11) | 0.0008 (13) | −0.0019 (12) |
C3 | 0.0283 (14) | 0.0233 (13) | 0.0256 (15) | 0.0002 (11) | −0.0012 (11) | −0.0040 (11) |
C4 | 0.0185 (12) | 0.0206 (12) | 0.0225 (14) | −0.0004 (9) | −0.0001 (10) | 0.0007 (11) |
C5 | 0.0281 (14) | 0.0191 (13) | 0.0190 (13) | 0.0004 (10) | 0.0017 (11) | 0.0002 (10) |
C6 | 0.0391 (16) | 0.0305 (15) | 0.0208 (14) | 0.0000 (12) | 0.0007 (12) | 0.0009 (12) |
C7 | 0.0221 (12) | 0.0237 (13) | 0.0166 (13) | −0.0011 (10) | 0.0004 (10) | −0.0002 (11) |
C8 | 0.0234 (11) | 0.0211 (12) | 0.0153 (12) | −0.0009 (10) | 0.0014 (10) | −0.0016 (11) |
C9 | 0.0157 (11) | 0.0237 (13) | 0.0161 (13) | −0.0003 (9) | 0.0031 (9) | 0.0015 (10) |
C10 | 0.0160 (11) | 0.0244 (13) | 0.0134 (12) | −0.0005 (9) | 0.0025 (9) | 0.0022 (10) |
C11 | 0.0234 (13) | 0.0275 (13) | 0.0125 (12) | −0.0021 (10) | −0.0020 (10) | 0.0023 (10) |
C12 | 0.0257 (14) | 0.0239 (13) | 0.0181 (14) | −0.0019 (10) | −0.0040 (11) | 0.0060 (11) |
C13 | 0.0191 (11) | 0.0193 (12) | 0.0200 (14) | 0.0001 (9) | 0.0010 (10) | 0.0021 (11) |
C14 | 0.0227 (13) | 0.0227 (13) | 0.0121 (12) | 0.0010 (10) | 0.0000 (10) | 0.0002 (10) |
C15 | 0.0215 (12) | 0.0222 (13) | 0.0158 (13) | 0.0020 (10) | −0.0013 (10) | 0.0037 (10) |
C16 | 0.0306 (13) | 0.0200 (13) | 0.0202 (13) | −0.0007 (10) | 0.0029 (11) | −0.0006 (11) |
C17 | 0.0287 (13) | 0.0204 (13) | 0.0301 (15) | 0.0000 (10) | 0.0022 (12) | −0.0021 (12) |
F1—C1 | 1.352 (3) | C8—H8 | 0.9500 |
O1—C9 | 1.231 (3) | C9—C10 | 1.483 (3) |
O2—C13 | 1.357 (3) | C10—C15 | 1.396 (4) |
O2—C16 | 1.444 (3) | C10—C11 | 1.404 (3) |
C1—C2 | 1.371 (5) | C11—C12 | 1.368 (4) |
C1—C6 | 1.381 (4) | C11—H11 | 0.9500 |
C2—C3 | 1.385 (4) | C12—C13 | 1.404 (4) |
C2—H2 | 0.9500 | C12—H12 | 0.9500 |
C3—C4 | 1.402 (4) | C13—C14 | 1.392 (3) |
C3—H3 | 0.9500 | C14—C15 | 1.389 (4) |
C4—C5 | 1.405 (4) | C14—H14 | 0.9500 |
C4—C7 | 1.461 (4) | C15—H15 | 0.9500 |
C5—C6 | 1.385 (4) | C16—C17 | 1.508 (4) |
C5—H5 | 0.9500 | C16—H16A | 0.9900 |
C6—H6 | 0.9500 | C16—H16B | 0.9900 |
C7—C8 | 1.324 (3) | C17—H17A | 0.9800 |
C7—H7 | 0.9500 | C17—H17B | 0.9800 |
C8—C9 | 1.480 (3) | C17—H17C | 0.9800 |
C13—O2—C16 | 116.6 (2) | C15—C10—C9 | 123.3 (2) |
F1—C1—C2 | 118.9 (3) | C11—C10—C9 | 118.9 (2) |
F1—C1—C6 | 118.3 (3) | C12—C11—C10 | 121.3 (2) |
C2—C1—C6 | 122.7 (3) | C12—C11—H11 | 119.3 |
C1—C2—C3 | 118.4 (3) | C10—C11—H11 | 119.3 |
C1—C2—H2 | 120.8 | C11—C12—C13 | 120.4 (2) |
C3—C2—H2 | 120.8 | C11—C12—H12 | 119.8 |
C2—C3—C4 | 121.2 (3) | C13—C12—H12 | 119.8 |
C2—C3—H3 | 119.4 | O2—C13—C14 | 124.8 (2) |
C4—C3—H3 | 119.4 | O2—C13—C12 | 116.0 (2) |
C3—C4—C5 | 118.4 (2) | C14—C13—C12 | 119.2 (2) |
C3—C4—C7 | 119.4 (3) | C15—C14—C13 | 119.8 (2) |
C5—C4—C7 | 122.1 (3) | C15—C14—H14 | 120.1 |
C6—C5—C4 | 120.5 (3) | C13—C14—H14 | 120.1 |
C6—C5—H5 | 119.7 | C14—C15—C10 | 121.4 (2) |
C4—C5—H5 | 119.7 | C14—C15—H15 | 119.3 |
C1—C6—C5 | 118.8 (3) | C10—C15—H15 | 119.3 |
C1—C6—H6 | 120.6 | O2—C16—C17 | 107.8 (2) |
C5—C6—H6 | 120.6 | O2—C16—H16A | 110.2 |
C8—C7—C4 | 127.7 (3) | C17—C16—H16A | 110.2 |
C8—C7—H7 | 116.2 | O2—C16—H16B | 110.2 |
C4—C7—H7 | 116.2 | C17—C16—H16B | 110.2 |
C7—C8—C9 | 121.2 (2) | H16A—C16—H16B | 108.5 |
C7—C8—H8 | 119.4 | C16—C17—H17A | 109.5 |
C9—C8—H8 | 119.4 | C16—C17—H17B | 109.5 |
O1—C9—C8 | 120.3 (2) | H17A—C17—H17B | 109.5 |
O1—C9—C10 | 120.4 (2) | C16—C17—H17C | 109.5 |
C8—C9—C10 | 119.3 (2) | H17A—C17—H17C | 109.5 |
C15—C10—C11 | 117.8 (2) | H17B—C17—H17C | 109.5 |
Two hydrogen bonds were found automatically by SHELXL; including the C14—H14 and O1, and C16—H16A and O1 donor–acceptor pairs. The remaining two pairs were identified by inspection. |
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3···F1i | 0.95 | 2.60 | 3.345 (3) | 136 |
C5—H5···O1ii | 0.95 | 2.70 | 3.544 (3) | 149 |
C14—H14···O1iii | 0.95 | 2.46 | 3.295 (3) | 146 |
C16—H16A···O1iii | 0.99 | 2.60 | 3.470 (3) | 146 |
Symmetry codes: (i) −x+1, −y, z−1/2; (ii) −x+1/2, y, z+1/2; (iii) −x+1, −y+1, z+1/2. |
All torsions were measured in Mercury (v2020.2.0; Macrae et al., 2020), with the exception of the torsion angles from this work, which were calculated using the CONF command of SHELXL2018/3 (Sheldrick, 2015b). |
Entry | –X | –R | Carbonyl–alkene torsion | Aryl–alkene torsion | Aryl–carbonyl torsion | Space group | CCDC Dep. No. |
1 | F | Me | 18.77 | 12.69 | 13.71 | P21/c | 660304a |
2 | F | OH | 2.41 | 0.99 | 6.18 | P1 | 2184323b |
3 | F | OMe | 18.95 | 11.50 | 2.92 | Pbca | 738291c |
4 | F | OEt | 12.00 | 1.20 | 1.20 | Pca21 | This work |
5 | Cl | OMe | 16.38 | 3.78 | 25.77 | Pbca | 2070477d |
6 | Br | OMe | 16.42 | 6.43 | 24.69 | Pc | 2062759e |
7 | 2-Cl | OEt | 5.16 | 4.47 | 0.44 | P1 | 1550212f |
8 | 3-Cl | OEt | 0.86 | 0.93 | 2.60 | P1 | 1587066f |
Notes: (a) Butcher et al. (2007); (b) Sobolev et al. (2022); (c) Zhao et al. (2009); (d) Whitwood et al. (2021); (e) Wilhelm et al. (2022); (f) Harshitha et al. (2018). |
Funding information
X-ray crystallography was performed in the Lumigen Instrument Center at Wayne State University, which is partially supported by NIH 3R01 EB027103–0251. Funding for this research was provided by: Shippensburg University Undergraduate Research Grant.
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