Crystal and mesophase structure of a bi­cyclo­hexyl cyano mesogen

Gupta, S.; Das, P.P.; Crispini, A.; Scarpelli, F.; Borbone, F.; Centore, R.

doi:10.1107/S2053229622010105

Crystal and mesophase structure of a bicyclohexyl cyano mesogen

S. Gupta, P. P. Das, A. Crispini, F. Scarpelli, F. Borbone and R. Centore

The phase behaviour of 4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzonitrile, C₂₂H₃₁N, 1, has been examined. This compound has two different solid phases, denoted I and II, and exhibits thermotropic liquid-crystalline behaviour, with a remarkable interval of stability of the mesophase between the lower melting solid phase (75 °C) and the isotropization temperature (247 °C). The crystal and molecular structures of solid phase I have been determined at 173 K. The cyclohexyl rings both adopt the chair conformation and are equatorially substituted. The packing of 1 in the crystalline state is driven by the antiparallel arrangement of cyano dipoles with the formation of close contacts involving the strong cyano acceptor and weak aromatic C—H or aliphatic C—H donors. The crystal packing is discussed and compared with X-ray diffraction data in the liquid-crystalline state. The combination of thermal analysis, optical polarizing microscopy and X-ray diffraction analysis suggests that the mesophase is a partially ordered smectic phase. The lamellar structure of the mesophase is retained in crystalline solid phase II obtained by cooling the liquid-crystalline phase.

Keywords: mesogen; texture; crystal packing; ordered smectics; crystal structure; benzonitrile.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S2053229622010105/yp3226sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S2053229622010105/yp3226Isup2.hkl Contains datablock I
	Portable Document Format (PDF) file https://doi.org/10.1107/S2053229622010105/yp3226sup3.pdf Supplementary material
	Chemical Markup Language (CML) file https://doi.org/10.1107/S2053229622010105/yp3226Isup4.cml Supplementary material

CCDC reference: 1857108

Computing details top

Data collection: COLLECT (Nonius, 1999); cell refinement: DIRAX/LSQ (Duisenberg et al., 2000); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2020); software used to prepare material for publication: WinGX (Farrugia, 2012).

4-[trans-4-(trans-4-Propylcyclohexyl)cyclohexyl]benzonitrile top

Crystal data top

C₂₂H₃₁N	Z = 2
M_r = 309.48	F(000) = 340
Triclinic, P1	D_x = 1.132 Mg m⁻³
a = 9.6230 (7) Å	Mo Kα radiation, λ = 0.71073 Å
b = 10.1300 (18) Å	Cell parameters from 93 reflections
c = 10.1510 (18) Å	θ = 3.5–23.0°
α = 104.686 (12)°	µ = 0.06 mm⁻¹
β = 103.935 (14)°	T = 173 K
γ = 98.024 (15)°	Prism, colourless
V = 907.6 (3) Å³	0.40 × 0.40 × 0.30 mm

Data collection top

Bruker–Nonius KappaCCD diffractometer	4117 independent reflections
Radiation source: normal-focus sealed tube	3129 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
Detector resolution: 9 pixels mm^-1	θ_max = 27.5°, θ_min = 2.5°
CCD rotation images, thick slices scans	h = −10→12
Absorption correction: multi-scan (SADABS; Bruker–Nonius, 2002)	k = −13→13
T_min = 0.965, T_max = 0.971	l = −13→12
12255 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.143	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.0719P)² + 0.1945P] where P = (F_o² + 2F_c²)/3
4117 reflections	(Δ/σ)_max < 0.001
209 parameters	Δρ_max = 0.32 e Å⁻³
0 restraints	Δρ_min = −0.15 e Å⁻³

Special details top

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. Data for single-crystal structure determination were measured on a Bruker–Nonius Kappa CCD diffractometer equipped with Oxford (Oxford, United Kingdom) Cryostream 700 apparatus, using graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). For data collection, a single crystal of approximate size 0.4 × 0.4 × 0.3 mm was attached to the tip of a glass fiber with epoxy glue, and data collection was performed at 173 (2) K. Reduction of data and semi-empirical absorption correction were done using the SADABS program (Bruker–Nonius, 2002). The structure was solved by direct methods SIR97 program (Altomare et al., 1999) and refined by the full-matrix least-squares method on F² using the SHELXL2015 program (Sheldrick, 2015) with the aid of the program WinGX (Farrugia, 2012). The analysis of the crystal packing was performed using the program Mercury (Macrae et al., 2020).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.84162 (15)	0.01984 (16)	−0.39658 (15)	0.0397 (3)
H1A	0.888723	−0.025297	−0.328427	0.060*
H1B	0.916926	0.078691	−0.419040	0.060*
H1C	0.780508	−0.051747	−0.483822	0.060*
C2	0.74624 (14)	0.10988 (13)	−0.33195 (14)	0.0317 (3)
H2A	0.808502	0.182382	−0.244214	0.038*
H2B	0.701566	0.157776	−0.399839	0.038*
C3	0.62548 (13)	0.02422 (12)	−0.29644 (13)	0.0280 (3)
H3A	0.671443	−0.016565	−0.222359	0.034*
H3B	0.570598	−0.054134	−0.382398	0.034*
C4	0.51666 (12)	0.10492 (11)	−0.24414 (12)	0.0230 (2)
H4	0.474927	0.150023	−0.317219	0.028*
C5	0.39027 (13)	0.00589 (12)	−0.22930 (12)	0.0259 (3)
H5A	0.430384	−0.044702	−0.162272	0.031*
H5B	0.340118	−0.064108	−0.322877	0.031*
C6	0.27836 (12)	0.08118 (12)	−0.17608 (12)	0.0253 (2)
H6A	0.202860	0.012472	−0.163207	0.030*
H6B	0.228968	0.121602	−0.249001	0.030*
C7	0.34774 (12)	0.19771 (12)	−0.03552 (11)	0.0226 (2)
H7	0.389643	0.153353	0.038192	0.027*
C8	0.47497 (13)	0.29588 (12)	−0.05101 (13)	0.0283 (3)
H8A	0.435337	0.345942	−0.118755	0.034*
H8B	0.525248	0.366384	0.042222	0.034*
C9	0.58641 (13)	0.21933 (13)	−0.10332 (13)	0.0287 (3)
H9A	0.663549	0.287426	−0.114815	0.034*
H9B	0.633736	0.177436	−0.030810	0.034*
C10	0.23605 (12)	0.27698 (11)	0.01610 (11)	0.0223 (2)
H10	0.202136	0.330148	−0.051758	0.027*
C11	0.10115 (13)	0.17884 (13)	0.01877 (13)	0.0283 (3)
H11A	0.050446	0.117191	−0.078976	0.034*
H11B	0.133433	0.118955	0.078465	0.034*
C12	−0.00672 (12)	0.25675 (13)	0.07645 (12)	0.0283 (3)
H12A	−0.089174	0.188293	0.079434	0.034*
H12B	−0.047150	0.309011	0.011295	0.034*
C13	0.06575 (12)	0.35873 (12)	0.22571 (11)	0.0233 (2)
H13	0.104632	0.303059	0.289162	0.028*
C14	0.19631 (13)	0.45952 (12)	0.22088 (13)	0.0278 (3)
H14A	0.246601	0.523231	0.317795	0.033*
H14B	0.161054	0.516882	0.159335	0.033*
C15	0.30514 (12)	0.38222 (13)	0.16392 (12)	0.0281 (3)
H15A	0.347324	0.332423	0.230929	0.034*
H15B	0.386352	0.451333	0.159835	0.034*
C16	−0.04613 (12)	0.42781 (12)	0.28390 (11)	0.0228 (2)
C17	−0.16062 (14)	0.34635 (13)	0.30854 (14)	0.0312 (3)
H17	−0.165307	0.248868	0.290450	0.037*
C18	−0.26768 (14)	0.40267 (13)	0.35845 (14)	0.0309 (3)
H18	−0.345100	0.344560	0.373460	0.037*
C19	−0.26044 (12)	0.54539 (12)	0.38634 (11)	0.0243 (2)
C20	−0.14628 (14)	0.62888 (13)	0.36475 (14)	0.0327 (3)
H20	−0.140452	0.726670	0.384918	0.039*
C21	−0.04058 (14)	0.57022 (13)	0.31384 (14)	0.0318 (3)
H21	0.036973	0.628502	0.299196	0.038*
C22	−0.37016 (13)	0.60842 (12)	0.43798 (12)	0.0265 (3)
N1	−0.45588 (12)	0.66094 (11)	0.47855 (12)	0.0343 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0299 (7)	0.0473 (8)	0.0382 (7)	0.0073 (6)	0.0174 (6)	−0.0005 (6)
C2	0.0287 (6)	0.0330 (6)	0.0330 (6)	0.0047 (5)	0.0166 (5)	0.0031 (5)
C3	0.0289 (6)	0.0265 (6)	0.0324 (6)	0.0097 (5)	0.0147 (5)	0.0078 (5)
C4	0.0233 (5)	0.0233 (5)	0.0249 (5)	0.0065 (4)	0.0105 (4)	0.0075 (4)
C5	0.0268 (6)	0.0217 (5)	0.0303 (6)	0.0050 (5)	0.0129 (5)	0.0055 (4)
C6	0.0225 (5)	0.0232 (5)	0.0285 (6)	0.0032 (4)	0.0102 (4)	0.0032 (4)
C7	0.0204 (5)	0.0257 (6)	0.0226 (5)	0.0062 (4)	0.0077 (4)	0.0067 (4)
C8	0.0241 (6)	0.0258 (6)	0.0311 (6)	0.0015 (5)	0.0124 (5)	−0.0004 (5)
C9	0.0213 (6)	0.0323 (6)	0.0305 (6)	0.0038 (5)	0.0115 (5)	0.0033 (5)
C10	0.0195 (5)	0.0259 (6)	0.0214 (5)	0.0057 (4)	0.0068 (4)	0.0053 (4)
C11	0.0212 (6)	0.0290 (6)	0.0293 (6)	0.0021 (5)	0.0095 (5)	−0.0014 (5)
C12	0.0193 (5)	0.0313 (6)	0.0285 (6)	0.0027 (5)	0.0075 (4)	−0.0002 (5)
C13	0.0211 (5)	0.0259 (5)	0.0230 (5)	0.0055 (4)	0.0084 (4)	0.0056 (4)
C14	0.0240 (6)	0.0273 (6)	0.0283 (6)	0.0013 (5)	0.0116 (5)	−0.0001 (5)
C15	0.0201 (5)	0.0320 (6)	0.0266 (6)	0.0019 (5)	0.0086 (4)	−0.0004 (5)
C16	0.0218 (5)	0.0260 (6)	0.0205 (5)	0.0054 (4)	0.0073 (4)	0.0056 (4)
C17	0.0328 (6)	0.0224 (6)	0.0417 (7)	0.0059 (5)	0.0203 (5)	0.0064 (5)
C18	0.0294 (6)	0.0267 (6)	0.0388 (7)	0.0036 (5)	0.0188 (5)	0.0064 (5)
C19	0.0237 (5)	0.0284 (6)	0.0217 (5)	0.0085 (5)	0.0077 (4)	0.0066 (4)
C20	0.0357 (7)	0.0255 (6)	0.0445 (7)	0.0112 (5)	0.0205 (6)	0.0126 (5)
C21	0.0313 (6)	0.0272 (6)	0.0431 (7)	0.0061 (5)	0.0202 (5)	0.0124 (5)
C22	0.0273 (6)	0.0254 (6)	0.0270 (6)	0.0053 (5)	0.0093 (5)	0.0071 (4)
N1	0.0351 (6)	0.0303 (5)	0.0418 (6)	0.0110 (5)	0.0190 (5)	0.0089 (5)

Geometric parameters (Å, º) top

C1—C2	1.5249 (16)	C10—C11	1.5312 (16)
C1—H1A	0.9800	C10—H10	1.0000
C1—H1B	0.9800	C11—C12	1.5265 (15)
C1—H1C	0.9800	C11—H11A	0.9900
C2—C3	1.5206 (16)	C11—H11B	0.9900
C2—H2A	0.9900	C12—C13	1.5315 (16)
C2—H2B	0.9900	C12—H12A	0.9900
C3—C4	1.5276 (14)	C12—H12B	0.9900
C3—H3A	0.9900	C13—C16	1.5182 (14)
C3—H3B	0.9900	C13—C14	1.5232 (16)
C4—C9	1.5224 (16)	C13—H13	1.0000
C4—C5	1.5272 (15)	C14—C15	1.5282 (14)
C4—H4	1.0000	C14—H14A	0.9900
C5—C6	1.5277 (14)	C14—H14B	0.9900
C5—H5A	0.9900	C15—H15A	0.9900
C5—H5B	0.9900	C15—H15B	0.9900
C6—C7	1.5304 (16)	C16—C21	1.3873 (16)
C6—H6A	0.9900	C16—C17	1.3932 (16)
C6—H6B	0.9900	C17—C18	1.3829 (15)
C7—C8	1.5313 (15)	C17—H17	0.9500
C7—C10	1.5405 (14)	C18—C19	1.3893 (16)
C7—H7	1.0000	C18—H18	0.9500
C8—C9	1.5268 (15)	C19—C20	1.3860 (17)
C8—H8A	0.9900	C19—C22	1.4430 (15)
C8—H8B	0.9900	C20—C21	1.3860 (16)
C9—H9A	0.9900	C20—H20	0.9500
C9—H9B	0.9900	C21—H21	0.9500
C10—C15	1.5300 (15)	C22—N1	1.1438 (15)

C2—C1—H1A	109.5	C15—C10—C7	111.68 (9)
C2—C1—H1B	109.5	C11—C10—C7	112.56 (9)
H1A—C1—H1B	109.5	C15—C10—H10	107.8
C2—C1—H1C	109.5	C11—C10—H10	107.8
H1A—C1—H1C	109.5	C7—C10—H10	107.8
H1B—C1—H1C	109.5	C12—C11—C10	112.91 (10)
C3—C2—C1	112.11 (11)	C12—C11—H11A	109.0
C3—C2—H2A	109.2	C10—C11—H11A	109.0
C1—C2—H2A	109.2	C12—C11—H11B	109.0
C3—C2—H2B	109.2	C10—C11—H11B	109.0
C1—C2—H2B	109.2	H11A—C11—H11B	107.8
H2A—C2—H2B	107.9	C11—C12—C13	111.99 (9)
C2—C3—C4	115.12 (10)	C11—C12—H12A	109.2
C2—C3—H3A	108.5	C13—C12—H12A	109.2
C4—C3—H3A	108.5	C11—C12—H12B	109.2
C2—C3—H3B	108.5	C13—C12—H12B	109.2
C4—C3—H3B	108.5	H12A—C12—H12B	107.9
H3A—C3—H3B	107.5	C16—C13—C14	114.86 (9)
C9—C4—C5	109.06 (9)	C16—C13—C12	110.77 (9)
C9—C4—C3	113.27 (9)	C14—C13—C12	108.66 (9)
C5—C4—C3	110.65 (9)	C16—C13—H13	107.4
C9—C4—H4	107.9	C14—C13—H13	107.4
C5—C4—H4	107.9	C12—C13—H13	107.4
C3—C4—H4	107.9	C13—C14—C15	111.68 (9)
C4—C5—C6	112.96 (9)	C13—C14—H14A	109.3
C4—C5—H5A	109.0	C15—C14—H14A	109.3
C6—C5—H5A	109.0	C13—C14—H14B	109.3
C4—C5—H5B	109.0	C15—C14—H14B	109.3
C6—C5—H5B	109.0	H14A—C14—H14B	107.9
H5A—C5—H5B	107.8	C14—C15—C10	113.20 (9)
C5—C6—C7	112.75 (9)	C14—C15—H15A	108.9
C5—C6—H6A	109.0	C10—C15—H15A	108.9
C7—C6—H6A	109.0	C14—C15—H15B	108.9
C5—C6—H6B	109.0	C10—C15—H15B	108.9
C7—C6—H6B	109.0	H15A—C15—H15B	107.8
H6A—C6—H6B	107.8	C21—C16—C17	117.61 (10)
C6—C7—C8	109.04 (9)	C21—C16—C13	122.91 (10)
C6—C7—C10	112.92 (9)	C17—C16—C13	119.48 (10)
C8—C7—C10	111.98 (9)	C18—C17—C16	122.19 (11)
C6—C7—H7	107.6	C18—C17—H17	118.9
C8—C7—H7	107.6	C16—C17—H17	118.9
C10—C7—H7	107.6	C17—C18—C19	119.09 (11)
C9—C8—C7	112.88 (9)	C17—C18—H18	120.5
C9—C8—H8A	109.0	C19—C18—H18	120.5
C7—C8—H8A	109.0	C20—C19—C18	119.76 (10)
C9—C8—H8B	109.0	C20—C19—C22	119.32 (10)
C7—C8—H8B	109.0	C18—C19—C22	120.92 (10)
H8A—C8—H8B	107.8	C19—C20—C21	120.24 (11)
C4—C9—C8	112.38 (9)	C19—C20—H20	119.9
C4—C9—H9A	109.1	C21—C20—H20	119.9
C8—C9—H9A	109.1	C20—C21—C16	121.10 (11)
C4—C9—H9B	109.1	C20—C21—H21	119.4
C8—C9—H9B	109.1	C16—C21—H21	119.4
H9A—C9—H9B	107.9	N1—C22—C19	178.58 (12)
C15—C10—C11	108.96 (9)

C1—C2—C3—C4	−174.55 (10)	C11—C12—C13—C14	56.51 (12)
C2—C3—C4—C9	−64.17 (13)	C16—C13—C14—C15	178.88 (9)
C2—C3—C4—C5	173.01 (10)	C12—C13—C14—C15	−56.44 (12)
C9—C4—C5—C6	54.31 (12)	C13—C14—C15—C10	56.92 (13)
C3—C4—C5—C6	179.55 (9)	C11—C10—C15—C14	−53.11 (13)
C4—C5—C6—C7	−55.35 (13)	C7—C10—C15—C14	−178.08 (9)
C5—C6—C7—C8	53.02 (12)	C14—C13—C16—C21	7.75 (16)
C5—C6—C7—C10	178.17 (9)	C12—C13—C16—C21	−115.82 (13)
C6—C7—C8—C9	−53.81 (13)	C14—C13—C16—C17	−172.51 (10)
C10—C7—C8—C9	−179.50 (9)	C12—C13—C16—C17	63.92 (14)
C5—C4—C9—C8	−54.70 (12)	C21—C16—C17—C18	1.20 (18)
C3—C4—C9—C8	−178.40 (9)	C13—C16—C17—C18	−178.55 (11)
C7—C8—C9—C4	56.60 (13)	C16—C17—C18—C19	−0.62 (19)
C6—C7—C10—C15	174.04 (9)	C17—C18—C19—C20	−0.41 (18)
C8—C7—C10—C15	−62.42 (12)	C17—C18—C19—C22	179.75 (11)
C6—C7—C10—C11	51.10 (12)	C18—C19—C20—C21	0.80 (19)
C8—C7—C10—C11	174.64 (9)	C22—C19—C20—C21	−179.35 (11)
C15—C10—C11—C12	52.83 (12)	C19—C20—C21—C16	−0.2 (2)
C7—C10—C11—C12	177.27 (9)	C17—C16—C21—C20	−0.79 (18)
C10—C11—C12—C13	−56.52 (13)	C13—C16—C21—C20	178.96 (11)
C11—C12—C13—C16	−176.44 (9)

Phase behaviour of 1 as reported in the literature (Cr is the crystal phase, Sm is the smectic phase, N is the nematic phase and I is the isotropic liquid phase) top

Reference	Phase transition temperatures (°C)
Kojima et al. (1983)	Cr 73.6 Sm 81.1 N 238.9 I
Poetsch et al. (1987)	Cr 55 N 184 I
Sasnovski et al. (1997)	Cr 80 N 247 I

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Crystal and mesophase structure of a bi­cyclo­hexyl cyano mesogen

Supporting information

Crystal and mesophase structure of a bicyclohexyl cyano mesogen