3-(4-{3,3,4,4,5,5-Hexafluoro-2-[5-(3-methoxy­phen­yl)-2-methyl-3-thien­yl]cyclo­pent-1-en­yl}-5-methyl-2-thien­yl)benzonitrile

An-yin Chen; Zhang-Gao Le; Gang Liu; Shou-Zhi Pu; Cong-Bin Fan

doi:10.1107/S1600536809034771

. 2009 Sep 5;65(Pt 10):o2352. doi: 10.1107/S1600536809034771

3-(4-{3,3,4,4,5,5-Hexafluoro-2-[5-(3-methoxyphenyl)-2-methyl-3-thienyl]cyclopent-1-enyl}-5-methyl-2-thienyl)benzonitrile

An-yin Chen ^a,^b, Zhang-Gao Le ^a, Gang Liu ^b, Shou-Zhi Pu ^b,^*, Cong-Bin Fan ^b

PMCID: PMC2970449 PMID: 21577821

Abstract

The title compound, C₂₉H₁₉F₆NOS₂, is a new unsymmetrical photochromic diarylethene derivative with different meta-phenyl substituents. The distance between the two reactive (i.e. can be irradiated to form a new chemical bond) C atoms is 3.501 (4) Å; the dihedral angles between the mean plane of the main central cyclopentene ring and the thiophene rings are 47.7 (5) and 45.1 (2)°, and those between the thiophene rings and the adjacent benzene rings are 29.4 (2) and 28.4 (3)°. The three C atoms and the F atoms of hexafuorocyclopentene ring are disordered over two positions, with site-occupancy factors of 0.751 (4) and 0.249 (4).

Related literature

For related compounds, see: Irie (2000 ▶); Irie et al. (2001 ▶); Pu et al. (2007 ▶, 2008 ▶). For the synthesis of the precursors, see: Pu et al. (2006 ▶); Yang et al. (2007 ▶). For ring-closure reactions, see: Ramamurthy & Venkatesan (1987 ▶).

Experimental

Crystal data

C₂₉H₁₉F₆NOS₂
M _r = 575.57
Triclinic,
a = 8.6134 (11) Å
b = 11.5938 (15) Å
c = 14.5281 (19) Å
α = 68.346 (2)°
β = 88.783 (2)°
γ = 82.158 (2)°
V = 1335.1 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.27 mm⁻¹
T = 296 K
0.15 × 0.13 × 0.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.961, T _max = 0.974
10275 measured reflections
4948 independent reflections
3155 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.127
S = 1.03
4948 reflections
383 parameters
16 restraints
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.23 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: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809034771/is2442sup1.cif

e-65-o2352-sup1.cif^{(29.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809034771/is2442Isup2.hkl

e-65-o2352-Isup2.hkl^{(242.3KB, hkl)}

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

Acknowledgments

This work was supported by the fund of the Key Laboratory of Nuclear Resources and Environment, East China Institute of Technology, Ministry of Education, China (No. 060607), the Key Scientific Project of the Education Ministry of China (208069), and the Graduate Innovation Fund of East China Institute of Technology (DYCA09002).

supplementary crystallographic information

Comment

Photochromic diarylethene is one of the most promising candidates for photoelectronic applications, such as optical storage (Irie, 2000; Pu et al., 2008), photoswitches (Irie et al., 2001; Pu et al., 2007) and waveguides. In the hexafluorocyclophentene ring of the title compound, C1=C5 [1.342 (4) Å] is clearly a double bond, being significantly shorter than the other single bonds, such as C1-C2 [1.502 (6) Å], C2-C3 [1.530 (6) Å], C3-C4 [1.583 (1) Å], C1-C7 [1.467 (4) Å], C5-C19 [1.471 (4) Å]. The title compound shows a photoactive antiparallel conformation (Fig. 1). The two independent planar thiophene ring systems have essentially identical geometries, and the dihedral angles between the main central cyclopent-1-ene ring and those of the two thiophene rings, S1/C6-C9 and S2/C18-C21, are 47.7 (5) and 45.1 (2)°, respectively. The dihedral angle between the thiophene and adjacent benzene ring is 29.4 (2)° for the C11-C16 benzene ring and 28.4 (3)° for the C23-C28 benzene ring. The two thiophene groups are linked by the C1=C5 double bond, with both of them attached to the ethylene group via the 2-position. The distance between the two reactive C atoms (C6···C18) is 3.501 (4) Å, which is short enough, theoretically, for the ring-closure reaction to take place in the crystalline phase (Ramamurthy & Venkatesan, 1987). Crystals of the title compound (1a) show photochromism in accordance with the expected ring closure, to form (1b) (Fig. 2); upon irradiation with 313 nm light, the colorless crystals turn blue rapidly. The blue compound when dissolved in hexane displays an absorption maximum at 583 nm. Upon irradiation with visible light with a wavelength greater than 450 nm, the blue crystals again turn initial colorless; a hexane solution has an absorption maximum at 294 nm.

Experimental

The title compound was originally derived from 3-bromo-5-(3-methoxyphenyl)-2-methylthiophene (1) (Yang et al., 2007) (5.0 g, 17.6 mmol) with an n-BuLi/hexane solution (7.1 mL, 2.5 M, 17.6 mmol) at 195 K under a nitrogen atmosphere, after 30 min, perfluorocyclopentene (2.2 mL, 17.6 mmol) was added quickly to the reaction solution. The mixture was stirred for 3 h at this temperature. The reaction mixture was filtered and evaporated in vacuo. The residue was purified by column chromatography on silica gel (hexane) to give (2-methyl-5- (3-methoxylphenyl)thiophene)perfluorocyclopent-1-ene, (2) (4.53 g, 11.3 mmol). Finally, to a stirred THF solution (50 ml) of 3-bromo-5-(3-cyanophenyl)-2-methylthiophene, (3) (Pu et al., 2006) (2.6 g, 9.6 mmol), an n-BuLi/hexane solution (3.8 ml, 2.5 M, 9.6 mmol) was slowly added in at 195 K under a nitrogen atmosphere. After 30 min, compound (2) (3.8 g, 9.6 mmol) was added and the mixture was stirred for 2 h at this temperature. The reaction mixture was extracted with diethyl ether and evaporated in vacuo, then purified by column chromatography (petroleum ether) to give the title compound, (Ia) (2.41 g, 4.2 mmol), in 43.7% yield. ¹H NMR (400 MHz, CDCl₃, TMS): δ 1.88 (s, 3H, -CH₃),1.90 (s, 3H, -CH₃), 3.76 (s, 3H, -OCH₃), 6.76-6.78 (dd, 1H, Hz, thiophene-H), 6.97 (s, 1H, thiophene-H), 7.04, 7.06 (d, 1H, J=8.0 Hz, phenyl -H), 7.17-7.24 (m, 2H, phenyl -H), 7.27 (s, 1H, phenyl-H), 7.41 (t, 1H, J=8.0 Hz, phenyl -H), 7.48, 7.50 (d, 1H, J=8.0 Hz, phenyl -H), 7.66, 7.68 (d, 1H, J=8.0 Hz, phenyl -H), 7.72 (s, 1H, phenyl-H); Elemental analysis: calc. for C₂₉H₁₉F₆NOS₂: C 60.20, H 3.83%. Found: C 58.84, H 3.77%; m.p.: 369.4–370.8 K.