6-Cyanona­phthalen-2-yl 4-hexyl­benzo­ate

Md Lutfor Rahman; H T Srinivasa; Mohd Yusoff Mashitah; Huey Chong Kwong; Ching Kheng Quah

doi:10.1107/S160053681400909X

. 2014 Apr 30;70(Pt 5):o620. doi: 10.1107/S160053681400909X

6-Cyanonaphthalen-2-yl 4-hexylbenzoate

Md Lutfor Rahman ^a,^*, H T Srinivasa ^b, Mohd Yusoff Mashitah ^a, Huey Chong Kwong ^c, Ching Kheng Quah ^d

PMCID: PMC4011248 PMID: 24860410

Abstract

In the title compound, C₂₄H₂₃NO₂, a whole molecule is disordered over two sets of sites with occupancies in a ratio of 0.692 (6):0.308 (6). In the major disorder component, the naphthalene ring system forms a dihedral angle of 68.6 (5)° with the benzene ring. The corresponding angle in the minor component is 81.6 (10)°. In the crystal, molecules are linked into chains propagating along the b-axis direction via weak C—H⋯O hydrogen bonds. The crystal packing is further consolidated by weak C—H⋯π interactions.

Related literature

For features of electro-optical display devices, see: Cox & Clecak (1976 ▶); Reddy & Tschierske (2006 ▶); Hanasaki et al. (2011 ▶) For applications of cyano groups in liquid crystal displays, see: Coates & Gray (1976 ▶); Klingbiel et al. (1974 ▶); Takezoe & Takanishi (2006 ▶). For related structures, see: Kuzmina et al. (2010 ▶); Blake et al. (1995 ▶); Li (2006 ▶). For standard bond-length data, see: Allen et al. (1987 ▶). graphic file with name e-70-0o620-scheme1.jpg

Experimental

Crystal data

C₂₄H₂₃NO₂
M _r = 357.43
Monoclinic,
a = 14.4712 (2) Å
b = 9.5592 (2) Å
c = 29.5386 (5) Å
β = 98.898 (1)°
V = 4036.99 (12) Å³
Z = 8
Cu Kα radiation
μ = 0.59 mm⁻¹
T = 298 K
0.29 × 0.11 × 0.08 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.848, T _max = 0.954
15700 measured reflections
3574 independent reflections
2344 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.069
wR(F ²) = 0.268
S = 1.10
3574 reflections
348 parameters
73 restraints
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S160053681400909X/lh5699sup1.cif

e-70-0o620-sup1.cif^{(41.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681400909X/lh5699Isup2.hkl

e-70-0o620-Isup2.hkl^{(175.4KB, hkl)}

Click here for additional data file.^{(7.2KB, cml)}

Supporting information file. DOI: 10.1107/S160053681400909X/lh5699Isup3.cml

CCDC reference: 998819

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

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 and Cg2 are the centroids of the C2A–C5A/C10A/C11A and C13B–C18B rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4A—H4AA⋯O2A ⁱ	0.95	2.44	3.303 (11)	149
C9B—H9BA⋯O2B ⁱⁱ	0.95	2.59	3.352 (11)	138
C14B—H14B⋯Cg1ⁱⁱⁱ	0.95	2.85	3.708 (14)	151
C20A—H20A⋯Cg2^iv	0.99	2.91	3.819 (14)	152
C19B—H19C⋯Cg2^iv	0.99	2.88	3.746 (19)	146

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

Acknowledgments

This research was supported by a PRGS Research Grant (No. RDU 130803).

supplementary crystallographic information

1. Comment

Electro-optical display devices require certain desirable features such as large positive dielectric anisotropy, nematic phase, low melting point, stability and lack of color (Cox & Clecak, 1976; Reddy & Tschierske, 2006; Hanasaki et al., 2011). To obtain such properties, a highly polar terminal cyano group can be incorporated to give a large dipole moment. Maximum dipole moment (90 degrees) indicates that the dipole moment is exactly parallel to the molecular short axis, which acts along the long axis of the molecule and helps to give the proper alignment for liquid crystal displays (Coates & Gray, 1976; Klingbiel et al., 1974; Takezoe & Takanishi, 2006). Here we report the synthesis and single-crystal X-ray study of an unsymmetrical naphthalene liquid crystal molecule. The shows a nematic phase after 379 K then a stable phase until an isotropic state at 411 K on a heating cycle. Upon cooling from the isotropic state, the nematic phase was reformed at 410 K, the phase is stabilized before crystallizes at 321 K.

The molecular structure of the title compound is shown in Fig 1. The whole molecule of the title compound is disordered over two positions with a refined site-occupancy ratio of 0.692 (6): 0.308 (6). For the major component, the naphthalene ring system (C2A—C11A) makes a dihedral angle of 68.6 (5)° with the benzene ring (C13A—C18A). In the minor component, the dihedral angle formed between the naphthalene ring system (C2B—C11B) and the benzene ring (C13B—C18B) is 81.6 (10)°. All the bond lengths (Allen et al., 1987) and angles are in normal ranges and compared with the closely related structures (Kuzmina et al., 2010; Blake et al., 1995; Li, 2006)

In the crystal, molecules are linked into chains propagating along the b-axis via weak C—H···O hydrogen bonds. Weak C—H···π interactions are also observed (see Table 1).

2. Experimental

A mixture of 4-hexylbenzoic acid (1.0 mmol), 2-cyano-6-hydroxy-naphthalene (1.0 mmol), dicyclohexylcarbodiimide (1.2 mmol) and catalytic quantity of N,N-dimethylaminopyridine in 5 ml of dry dichloromethane was stirred at room temperature for 1 h. Progress of the reaction was monitored by TLC (ethyl acetate: pet ether 2:8). After completion of the reaction, the reaction mass was diluted with water and extracted into dichloromethane (25 ml). The organic layer was washed with diluted acetic acid and water. The organic layer was dried over anhydrous sodium sulfate and the solvent was removed under reduced pressure. The crude product was purified by column chromatography by using ethyl acetate: petroleum ether (2:8) as eluent and the product was recrystallization from chloroform. Yield = 70% as colourless block crystals. IR(KBr): v = 2920, 2856, 2224, 1724, 1454, 1066, 902 cm^-1; ¹H NMR (400 MHz, CDCl₃): δ = 8.11–6.98 (m, 10H, Ar—H), 2.54 (t, J = 1.37 Hz, 2H, Ar—CH₂–), 1.47–1.44 (m, 8H, alkyl-CH₂–), 0.91 (m, 3H, alkyl-CH₃) p.p.m.; Elemental analysis calcd for C₂₄H₂₃NO₂ (%): C 80.64, H 6.49, N 3.92; found. C 80.69, H 6.54, N 4.07.