1-(2-Chloro­phen­yl)-2-(2-methyl-5-phenyl-3-thien­yl)-3,3,4,4,5,5-hexa­fluoro­cyclo­pent-1-ene: a new photochromic diaryl­ethene

Shanshan Gong; Congbin Fan; Weijun Liu; Gang Liu

doi:10.1107/S1600536808013330

. 2008 May 10;64(Pt 6):o1028. doi: 10.1107/S1600536808013330

1-(2-Chlorophenyl)-2-(2-methyl-5-phenyl-3-thienyl)-3,3,4,4,5,5-hexafluorocyclopent-1-ene: a new photochromic diarylethene

Shanshan Gong ^a, Congbin Fan ^a,^*, Weijun Liu ^a, Gang Liu ^a

PMCID: PMC2961463 PMID: 21202552

Abstract

The title compound, C₂₂H₁₃ClF₆S, is a hybrid diarylethene derivative with one 3-thienyl substituent, and a Cl-substituted six-membered aryl unit bonded to the double bond of a hexafluorocyclopentene ring. In the crystal structure, the molecule adopts a photo-active antiparallel conformation that can undergo effective photocyclization reactions. The distance between the two reactive C atoms is 3.848 (3) Å. The dihedral angles between the least-squares cyclopentene plane and those of the adjacent thiophene and chlorophenyl rings are 49.39 (8) and 59.88 (8)°, respectively. The F atoms are disordered over two positions, with site occupancy factors of 0.6 and 0.4.

Related literature

For related literature, see: Dürr & Bouas-Laurent (1990 ▶); Irie (2000 ▶); Kobatake & Irie (2004 ▶); Ramamurthy & Venkatesan (1987 ▶); Tian & Yang (2004 ▶); Woodward & Hoffmann (1970 ▶); Zheng et al. (2007 ▶); Peters et al. (2003 ▶).

Experimental

Crystal data

C₂₂H₁₃ClF₆S
M _r = 458.83
Triclinic,
a = 8.8064 (10) Å
b = 10.4185 (12) Å
c = 11.6563 (13) Å
α = 85.265 (1)°
β = 76.935 (1)°
γ = 76.324 (1)°
V = 1011.8 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.35 mm⁻¹
T = 291 (2) K
0.46 × 0.37 × 0.27 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.835, T _max = 0.910
7557 measured reflections
3741 independent reflections
3039 reflections with I > 2σ(I)
R _int = 0.013

Refinement

R[F ² > 2σ(F ²)] = 0.036
wR(F ²) = 0.100
S = 1.03
3741 reflections
326 parameters
66 restraints
H-atom parameters constrained
Δρ_max = 0.15 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: SMART (Bruker,1997 ▶); cell refinement: SAINT (Bruker, 1997 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▶) and ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808013330/dn2342sup1.cif

e-64-o1028-sup1.cif^{(20.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808013330/dn2342Isup2.hkl

e-64-o1028-Isup2.hkl^{(183.4KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

This work was supported by the Natural Science Foundation of Jiangxi, China (0620012) and the Science Fund of the Education Office of Jiangxi, China ([2007]279).

supplementary crystallographic information

Comment

Organic photochromic materials have attracted much attention, because of their potential application to optical memory media and optical switches. (Dürr & Bouas-Laurent, 1990; Tian & Yang, 2004). Among all organic photochromic compounds, diarylethenes with heterocyclic aryl groups are the most promising candidates for those application, mainly due to the excellent thermal stability of the respective isomers, notable fatigue resistance, and high reactivity in the solid state (Irie, 2000). The backbone of all photochromic perfluorocyclopentene systems are composed of five-membered heterocyclic rings (Zheng et al., 2007) or the combination of a five-membered aryl ring and a vinyl group. we decided to investigate if replacing the five-membered heterocyclic ring in the diarylethene with a six-membered aryl ring would induce novel characteristics. This paper presents the synthesis and crystal structure of the title compound a six-membered aryl ring group bearing a Cl atom.

The thienyl and the 2-chlorophenyl rings are in cis-position with respect to the C7=C11 double bond (Fig. 1). They are located on each side of the fluorocyclopentene ring, as reflected by the torsion angles C1—C6—C7—C11 [-60.52 ( 0.31)°] and C7—C11—C12—C13 [45.95 (23)°]. The dihedral angles between the least-square cyclopentene plane and those of the adjacent thiophene and chloro-phenyl rings are 49.39 (8)° and 59.88 (8)° respectively.

Such conformation is crucial for the compound to exhibit photochromic and photoinduced properties (Woodward & Hoffmann, 1970). The intramolecular distance between the two reactive C atoms (C1—C13) is 3.848 (3) Å. This distance indicates that the crystal can be expected to undergo photochromism to form compound (Ib)( Fig. 2), because photochromic reactivity usually appears when distance between the reactive C atoms is less than 4.2 Å (Ramamurthy & Venkatesan, 1987; Kobatake et al., 2004). Crystal of (Ib) shows photochromism in accordance with the expected ring closure to form (Ib). Upon irradiation with 313 nm light, the colorless single-crystal of (Ia) turned red quickly. When the red crystal was dissolved in hexane, the solution also showed a red color, with an absorption maximum at 523 nm, consistent with the presence of the closed-ring isomer (Ib). Upon irradiation with visible light with wavelength greater than 510 nm, the red crystal can return to its initial colorless state, and the absorption spectrum of the hexane solution containing the colorless crystal is the same as that of solution of the open-ring form, (Ia), with the absorption maximum at 273 nm.

Experimental

Compound (Ia) was prepared from (2-methyl-5-phenyl-3-thienyl)- 3,3,4,4,5,5-hexafluorocyclopent-1-ene (1.83 g, 5.00 mmol) (Peters et al., 2003) and 2-bromo-chlorobenzene (0.96 g, 5.00 mmol). To a stirred solution of compound 2-bromo-chlorobenzene (0.96 g, 5.00 mmol) in THF (80 ml) was added dropwise a 2.5 mol/L n-BuLi in hexane (2.0 ml) at 195 K under a nitrogen atmosphere (Fig. 3). Stirring was continued for 30 min, (2-methyl-5-phenyl-3-thienyl)- 3,3,4,4,5,5-hexafluorocyclopent-1-ene (1.83 g, 5.00 mmol) was slowly added to the reaction mixture, and the mixture was stirred for 2.0 h at 195 K. The reaction was stopped by the addition of water. Through a series of operations, [1-(2-methyl-5-phenyl-3-thienyl), 2-(2-chlorophenyl)]- 3,3,4,4,5,5-hexafluorocyclopent-1-ene (1.32 g, 2.88 mmol) was obtained in 57.5% yield by column chromatography on SiO₂ using hexane as the eluent. Finally the colorless crystals were obtained by slow vapour diffusion of chloroform and hexane(1:2). The title compound was characterized by melting point, elemental analysis and NMR(m.p.361.1–361.7 K). ¹HNMR (400 MHz, CDCl₃, TMS): δ 2.08 (s, 3H, –CH₃), 7.14 (s, 1H, thiophene-H), 7.27, 7.29 (d, 2H, J = 8.0 Hz, benzene-H), 7.33–7.38 (m, 4H, benzene-H), 7.40 (m, 1H, benzene-H), 7.46, 7.48 (d, 2H, J = 8.0 Hz, benzene-H); ¹³C NMR (100 MHz, CDCl₃): δ 14.55, 123.10, 125.11, 125.59, 126.98, 127.75, 128.91, 130.43, 130.55, 131.25, 133.45, 133.70, 140.70, 141.73; IR (KBr, cm^-1): 754, 853, 987, 1053, 1132, 1192, 1272, 1330, 1441, 1473, 1502, 1598, 1674, 2925, 3064; Anal. Calcd. for C₂₄H₁₉ClF₆S(%): C, 57.59, H, 2.86, Found: C, 57.28, H, 2.59.