Crystal Structure of (E)-2-(3,3,3-tri-fluoro-prop-1-en-1-yl)aniline.

The mol-ecule of the title compound, C9H8F3N, adopts an E configuration with respect to the C=C double bond. The dihedral angle between the benzene ring and the prop-1-enyl group is 25.4 (3)°. In the crystal, mol-ecules are linked via pairs of N-H⋯F hydrogen bonds into inversion dimers with an R 2 2(16) ring motif. The dimers are linked by C-H⋯N hydrogen bonds, forming a ribbon structure along the b-axis direction. The ribbons are linked by N-H⋯π and C-H⋯π inter-actions, generating a three-dimensional network.

Chemical context

Fluorescein, rhodamine etc. are water-soluble fluorescent reagents. Their derivatives exhibit strong fluorescence in aqueous solution and so can be utilized as ion-probes and in bio-imaging (Aron et al., 2016 ▸; Li et al., 2016 ▸). However, complicated procedures are required to obtain them. It is therefore desirable to develop a new fluorescent reagent with a simple structure that can be obtained by a short-step synthetic process. The title compound has a quite simple structure and is a small mol­ecule, consisting of aniline and 3,3,3-tri­fluoro­prop-1-enyl units, which emits strong fluorescence not only in organic solvents but also in an aqueous medium (H2O/DMSO, 90:10, v/v). Since aniline derivatives with 2,4-bis­(3,3,3-tri­fluoro­prop-1-en­yl) have been used as fluoro­genic substrates for dipepeptidyl peptidase-4 (Ogawa et al., 2017 ▸), the title compound can be treated as a simple but essential component in emitting fluorescence. Hence, it is important to study the relationship between the fluorescent properties and the mol­ecular structure of the title compound. We report here its mol­ecular and crystal structure.

Structural commentary

The mol­ecular structure of the title compound is shown in Fig. 1 ▸. The mol­ecule adopts an E configuration with respect to the C=C double bond. The dihedral angle between the benzene ring and the prop-1-enyl group is 25.4 (3)°. The C5—C10—C11—C12 and C9—C10—C11—C12 torsion angles are −158.9 (3) and 24.6 (4)°, respectively. The bond lengths and angles in the title compound are normal and agree with those in other tri­fluoro­propenylaniline compounds (Shimizu et al., 2009 ▸; Lin et al., 2014 ▸).

Figure 1

The mol­ecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.

Supra­molecular features

In the crystal, two mol­ecules are associated through a pair of inter­molecular N—H⋯F hydrogen bonds (Table 1 ▸), forming a centrosymmetric dimer with an (16) ring motif (Fig. 2 ▸). The dimers are further linked by C—H⋯N hydrogen bonds (Table 1 ▸), forming a ribbon with a C(6) chain motif along the b-axis direction. The ribbons are linked by N—H⋯π and C—H⋯π inter­actions (Table 1 ▸), generating a three-dimensional network.

Table 1

Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C5–C10 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4A⋯F2i	0.90 (3)	2.46 (4)	3.352 (3)	169 (3)
C12—H12⋯N4ii	0.95	2.56	3.432 (4)	152
N4—H4B⋯Cg1iii	0.88 (3)	2.59 (4)	3.315 (2)	140 (3)
C9—H9⋯Cg1iv	0.95	2.73	3.480 (3)	136

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

Figure 2

A packing diagram of the title compound, viewed along the b axis. The N—H⋯F and C—H⋯N hydrogen bonds and N—H⋯π and C—H⋯π inter­actions are shown as dashed lines.

Database survey

A search of the Cambridge Structural Database (CSD, Version 5.39; May 2018; Groom et al., 2016 ▸) gave 16 hits for 2-(3,3,3-tri­fluoro­prop-1-en-1-yl)aza­benzene derivatives, and gave 18 and 45 hits for (E)-3,3,3-tri­fluoro­prop-1-enyl and 2-amino­phenyl-1-enyl fragments, respectively. Of these structures, those that resemble the title compound are 4-[2-(3,3,3-tri­fluoro­prop-1-en-1-yl)phen­yl]morpholine (Lin et al., 2014 ▸), N-acetyl-N-{2-[(Z)-2-chloro-3,3,3-tri­fluoro­prop-1-en­yl]phen­yl}acetamide (Niu et al., 2009 ▸) and (E,E)-1,4-di­piperidino-2,5-bis­(3,3,3-tri­fluoro­prop-1-en­yl)benzene (Shim­izu et al., 2009 ▸).

Synthesis and crystallization

The title compound was prepared by a modification of a reported procedure (Omote et al., 2013 ▸). In a glove box purged with argon gas, iodo­aniline (1.0 mmol), (2-methyl­all­yl)palladium(II) chloride dimer (0.1mmol), CuF2 (2.0 mmol) and 2,2′-bipyridyl (2.0 mmol) were placed in a flask. To the flask were added anhydrous DMF (6.0 ml) and (E)-trimethyl-(3,3,3-tri­fluoro­prop-1-en­yl)silane (2.0 mmol), and the mixture was stirred at 353 K. After the reaction mixture had been stirred for 4 h, it was poured into ice–water. The mixture was extracted with CH2Cl2, and the organic layer was dried over anhydrous MgSO4. After the solid had been filtered off, the solvent was removed in vacuo, and the residue was purified by silica gel column chromatography to give the product in 68% yield. Colourless single crystals were obtained by recrystallization from an ethyl acetate–hexane (1:10, v/v) solution (m.p. 321–322 K). 1H NMR (CDCl3) δ: 3.81 (2H, s), 6.13 (1H, qd, J = 15.9, 6.5 Hz), 6.72 (1H, dd, J = 8.2, 0.9 Hz), 6.80 (1H, dt, J = 7.5, 0.9 Hz), 7.18 (1H, dt, J = 7.8, 1.4 Hz), 7.24 (1H, qd, J = 15.9, 2.1 Hz), 7.29 (1H, dd, J = 7.8, 1.4 Hz). 13C NMR (CDCl3) δ: 116.6 (q, J = 33.4 Hz), 116.8, 119.2, 119.4, 123.6 (q, J = 269.0 Hz), 127.9, 130.9, 133.3 (q, J = 6.8 Hz), 144.8. 19F NMR (CDCl3) δ: 12.07 (3F, dd, J = 6.5, 2.2 Hz). MS m/z 187 (M +), HRMS calculated for C9H8F3N 187.1617 (M +), found 187.0603.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The amino H atoms were located in a difference Fourier map and refined freely. The C-bound H atoms were positioned geometrically (C—H = 0.93–0.97 Å) and refined using a riding model with U iso(H) = 1.2U eq(C). One outlier (11) was omitted in the last cycle of refinement.

Table 2

Experimental details

Crystal data
Chemical formula	C9H8F3N
M r	187.16
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	123
a, b, c (Å)	7.3925 (4), 6.2777 (3), 18.6065 (9)
β (°)	96.243 (7)
V (Å3)	858.37 (8)
Z	4
Radiation type	Cu Kα
μ (mm−1)	1.16
Crystal size (mm)	0.40 × 0.26 × 0.08
Data collection
Diffractometer	Rigaku R-AXIS RAPID
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995 ▸)
T min, T max	0.543, 0.912
No. of measured, independent and observed [F 2 > 2.0σ(F 2)] reflections	4753, 1566, 1178
R int	0.049
(sin θ/λ)max (Å−1)	0.602
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.061, 0.175, 1.03
No. of reflections	1566
No. of parameters	126
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3)	0.49, −0.39

Computer programs: RAPID-AUTO (Rigaku, 2006 ▸), SIR92 (Altomare et al., 1993 ▸), SHELXL2014/7 (Sheldrick, 2015 ▸), PLATON (Spek, 2009 ▸) and CrystalStructure (Rigaku, 2016 ▸).

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989018012756/is5499sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989018012756/is5499Isup2.hkl

CCDC reference: 1866671

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

C9H8F3N	F(000) = 384.00
Mr = 187.16	Dx = 1.448 Mg m−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54187 Å
a = 7.3925 (4) Å	Cell parameters from 4006 reflections
b = 6.2777 (3) Å	θ = 4.8–68.2°
c = 18.6065 (9) Å	µ = 1.16 mm−1
β = 96.243 (7)°	T = 123 K
V = 858.37 (8) Å3	Platelet, colourless
Z = 4	0.40 × 0.26 × 0.08 mm

Rigaku R-AXIS RAPID diffractometer	1178 reflections with F2 > 2.0σ(F2)
Detector resolution: 10.000 pixels mm-1	Rint = 0.049
ω scans	θmax = 68.2°, θmin = 4.8°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −8→8
Tmin = 0.543, Tmax = 0.912	k = −6→7
4753 measured reflections	l = −22→22
1566 independent reflections

Refinement on F2	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.175	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ2(Fo2) + (0.1029P)2 + 0.1188P] where P = (Fo2 + 2Fc2)/3
1566 reflections	(Δ/σ)max < 0.001
126 parameters	Δρmax = 0.49 e Å−3
0 restraints	Δρmin = −0.39 e Å−3
Primary atom site location: structure-invariant direct methods

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. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F2. R-factor (gt) are based on F. The threshold expression of F2 > 2.0 sigma(F2) is used only for calculating R-factor (gt).

	x	y	z	Uiso*/Ueq
F1	0.2762 (3)	−0.0078 (3)	0.52691 (8)	0.0597 (7)
F2	0.3860 (2)	−0.3171 (3)	0.51696 (8)	0.0569 (6)
F3	0.0979 (2)	−0.2730 (4)	0.50888 (9)	0.0661 (7)
N4	0.3895 (3)	0.4055 (4)	0.31939 (13)	0.0343 (6)
C5	0.3078 (3)	0.2521 (4)	0.27331 (13)	0.0272 (6)
C6	0.2853 (3)	0.2886 (4)	0.19799 (12)	0.0293 (6)
H6	0.3289	0.4171	0.1791	0.035*
C7	0.2009 (3)	0.1398 (4)	0.15202 (13)	0.0311 (6)
H7	0.1863	0.1670	0.1015	0.037*
C8	0.1362 (4)	−0.0502 (4)	0.17775 (12)	0.0311 (6)
H8	0.0788	−0.1528	0.1453	0.037*
C9	0.1567 (3)	−0.0871 (4)	0.25119 (12)	0.0276 (6)
H9	0.1123	−0.2164	0.2691	0.033*
C10	0.2413 (3)	0.0608 (4)	0.30004 (11)	0.0220 (6)
C11	0.2527 (3)	0.0253 (4)	0.37877 (12)	0.0276 (6)
H11	0.2651	0.1475	0.4090	0.033*
C12	0.2471 (3)	−0.1615 (4)	0.41076 (12)	0.0310 (6)
H12	0.2410	−0.2856	0.3814	0.037*
C13	0.2497 (4)	−0.1887 (4)	0.48945 (13)	0.0346 (7)
H4A	0.448 (4)	0.362 (6)	0.3618 (18)	0.070 (11)*
H4B	0.448 (5)	0.497 (5)	0.2944 (18)	0.067 (11)*

	U11	U22	U33	U12	U13	U23
F1	0.1045 (18)	0.0494 (12)	0.0245 (8)	0.0050 (11)	0.0032 (10)	−0.0071 (8)
F2	0.0673 (13)	0.0635 (13)	0.0370 (10)	0.0222 (10)	−0.0073 (9)	0.0154 (8)
F3	0.0571 (12)	0.1073 (17)	0.0329 (9)	−0.0274 (11)	−0.0002 (8)	0.0251 (10)
N4	0.0379 (14)	0.0297 (13)	0.0346 (13)	−0.0050 (11)	0.0003 (11)	−0.0022 (11)
C5	0.0267 (13)	0.0255 (13)	0.0292 (13)	0.0036 (11)	0.0021 (10)	−0.0008 (11)
C6	0.0319 (14)	0.0290 (14)	0.0271 (13)	0.0045 (12)	0.0035 (10)	0.0050 (11)
C7	0.0310 (14)	0.0389 (16)	0.0236 (12)	0.0041 (12)	0.0035 (10)	0.0037 (11)
C8	0.0332 (15)	0.0355 (15)	0.0239 (13)	−0.0023 (12)	0.0000 (11)	−0.0043 (11)
C9	0.0295 (13)	0.0276 (14)	0.0254 (12)	0.0026 (12)	0.0009 (10)	0.0004 (11)
C10	0.0211 (13)	0.0241 (13)	0.0201 (11)	0.0020 (10)	−0.0010 (9)	−0.0007 (10)
C11	0.0295 (15)	0.0293 (14)	0.0232 (12)	0.0010 (11)	−0.0008 (10)	−0.0024 (10)
C12	0.0388 (15)	0.0315 (15)	0.0218 (12)	0.0012 (12)	−0.0008 (11)	0.0002 (11)
C13	0.0400 (16)	0.0373 (16)	0.0254 (13)	0.0004 (13)	−0.0013 (11)	0.0035 (11)

F1—C13	1.336 (3)	C7—H7	0.9500
F2—C13	1.348 (3)	C8—C9	1.378 (3)
F3—C13	1.326 (3)	C8—H8	0.9500
N4—C5	1.383 (3)	C9—C10	1.398 (3)
N4—H4A	0.90 (3)	C9—H9	0.9500
N4—H4B	0.88 (3)	C10—C11	1.475 (3)
C5—C10	1.409 (3)	C11—C12	1.318 (3)
C5—C6	1.412 (3)	C11—H11	0.9500
C6—C7	1.371 (3)	C12—C13	1.472 (3)
C6—H6	0.9500	C12—H12	0.9500
C7—C8	1.389 (4)
C5—N4—H4A	118 (2)	C10—C9—H9	119.1
C5—N4—H4B	109 (2)	C9—C10—C5	119.0 (2)
H4A—N4—H4B	116 (3)	C9—C10—C11	121.2 (2)
N4—C5—C10	121.3 (2)	C5—C10—C11	119.7 (2)
N4—C5—C6	119.9 (2)	C12—C11—C10	125.6 (2)
C10—C5—C6	118.7 (2)	C12—C11—H11	117.2
C7—C6—C5	120.3 (2)	C10—C11—H11	117.2
C7—C6—H6	119.8	C11—C12—C13	123.7 (2)
C5—C6—H6	119.8	C11—C12—H12	118.1
C6—C7—C8	121.4 (2)	C13—C12—H12	118.1
C6—C7—H7	119.3	F3—C13—F1	106.1 (2)
C8—C7—H7	119.3	F3—C13—F2	106.1 (2)
C9—C8—C7	118.7 (2)	F1—C13—F2	104.4 (2)
C9—C8—H8	120.6	F3—C13—C12	113.4 (2)
C7—C8—H8	120.6	F1—C13—C12	113.9 (2)
C8—C9—C10	121.8 (2)	F2—C13—C12	112.1 (2)
C8—C9—H9	119.1
N4—C5—C6—C7	−178.5 (2)	N4—C5—C10—C11	2.2 (4)
C10—C5—C6—C7	−0.3 (4)	C6—C5—C10—C11	−176.1 (2)
C5—C6—C7—C8	−0.3 (4)	C9—C10—C11—C12	24.6 (4)
C6—C7—C8—C9	0.5 (4)	C5—C10—C11—C12	−158.9 (3)
C7—C8—C9—C10	−0.3 (4)	C10—C11—C12—C13	−176.8 (2)
C8—C9—C10—C5	−0.2 (4)	C11—C12—C13—F3	115.4 (3)
C8—C9—C10—C11	176.3 (2)	C11—C12—C13—F1	−6.2 (4)
N4—C5—C10—C9	178.7 (2)	C11—C12—C13—F2	−124.5 (3)
C6—C5—C10—C9	0.5 (3)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4A···F2i	0.90 (3)	2.46 (4)	3.352 (3)	169 (3)
C12—H12···N4ii	0.95	2.56	3.432 (4)	152
N4—H4B···Cg1iii	0.88 (3)	2.59 (4)	3.315 (2)	140 (3)
C9—H9···Cg1iv	0.95	2.73	3.480 (3)	136