(E,E,E,E)-2,3,5,6-Tetra-kis{2-[4-(dimethyl-amino)-phen-yl]ethen-yl}pyrazine.

In the title compound, C(44)H(48)N(6), the essentially planar mol-ecule [maximum deviation from the mean plane of the π system of 0.271 (3) Å] is located on a crystallographic centre of inversion. The almost planar (angle sums at N atoms = 357.6 and 357.1°) dimethyl-amino groups and short C-N bonds of the aniline groups [both 1.379 (4) Å] indicate strong electronic coupling between these groups and the central pyrazine ring.

Related literature

For similar tetra­styryl­pyrazines prepared by acid- or base-catalysed condensations, see: Takahashi & Satake (1952 ▶). For photochemical properties of tetra­styryl­pyrazines, see: Collette & Harper (2003 ▶); Rumi et al. (2008 ▶) For star-shaped chromo­phores, see: Detert et al. (2010 ▶); Detert & Sugiono (2005 ▶); Strehmel et al. (2003 ▶); Nemkovich et al. (2010 ▶). For a two-dimensional homologue of the linear distyryl­pyrazine, see: Fischer et al. (2011 ▶). For cruciforms with a central benzene ring and phenyl­ene­vinyl­ene arms, see: Niazimbetova et al. (2002 ▶), Hauck et al. (2007 ▶), Zucchero et al. (2010 ▶). For probes for thrombine detection, see: Yan et al. (2011 ▶).

Experimental

Crystal data

C44H48N6

M = 660.88

Monoclinic,

a = 10.763 (2) Å

b = 16.6751 (19) Å

c = 10.755 (3) Å

β = 101.109 (9)°

V = 1894.1 (7) Å3

Z = 2

Cu Kα radiation

μ = 0.53 mm−1

T = 193 K

0.30 × 0.20 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer

3778 measured reflections

3584 independent reflections

2384 reflections with I > 2σ(I)

R int = 0.073

3 standard reflections every 60 min intensity decay: 2%

Refinement

R[F 2 > 2σ(F 2)] = 0.081

wR(F 2) = 0.239

S = 1.11

3584 reflections

230 parameters

H-atom parameters constrained

Δρmax = 0.44 e Å−3

Δρmin = −0.31 e Å−3

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 Software; data reduction: CORINC (Dräger & Gattow, 1971 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: PLATON.

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811019714/bt5556sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811019714/bt5556Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536811019714/bt5556Isup3.cml

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

C44H48N6	F(000) = 708
Mr = 660.88	Dx = 1.159 Mg m−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2ybc	Cell parameters from 3 reflections
a = 10.763 (2) Å	θ = 36–47°
b = 16.6751 (19) Å	µ = 0.53 mm−1
c = 10.755 (3) Å	T = 193 K
β = 101.109 (9)°	Needle, red
V = 1894.1 (7) Å3	0.30 × 0.20 × 0.10 mm
Z = 2

Enraf–Nonius CAD-4 diffractometer	Rint = 0.073
Radiation source: rotating anode	θmax = 69.9°, θmin = 4.2°
graphite	h = 0→13
ω/2θ scans	k = 0→20
3778 measured reflections	l = −13→12
3584 independent reflections	3 standard reflections every 60 min
2384 reflections with I > 2σ(I)	intensity decay: 2%

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)] = 0.081	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.239	H-atom parameters constrained
S = 1.11	w = 1/[σ2(Fo2) + (0.1104P)2 + 0.8327P] where P = (Fo2 + 2Fc2)/3
3584 reflections	(Δ/σ)max < 0.001
230 parameters	Δρmax = 0.44 e Å−3
0 restraints	Δρmin = −0.31 e Å−3

Experimental. 1H-NMR (CDCl3, 400 MHz): δ (ppm) = 7.88 (d, 3J = 15.4 Hz, 4H, 2-H ethenyl), 7.58 (d, 3J = 8.8 Hz, 8H, 2-H, 6-H phenyl), 7.38 (d, 3J = 15.4 Hz, 4H, 1-H ethenyl), 6.75 (d, 3J = 8.8 Hz, 8H, 3-H, 6-H phenyl), 3.03 (s, 24H, CH3). 13C-NMR (CDCl3, 75 MHz): δ (ppm) = 150.5 (C-4 phenyl), 144.8 (C-2, C-3, C-4, C-5 pyrazine), 134.8 (C-2 ethenyl), 128.6 (C-3, C-5 phenyl), 125.7 (C-1 phenyl), 118.5 (C-1 ethenyl), 112.2 (C-2, C-6 phenyl), 40.4 (CH3). FD-MS: m/z (g/mol) = 220.1 (1.3 %) [M3+], 330.2 (10.8 %) [M2+], 660.2 (100 %) [M+]. IR (ATR): ν = 2852, 1595, 1519, 1430, 1356, 1322, 1153, 965, 946, 799 cm-1. UV-Vis (CH2Cl2): λmax = 448 nm, ε = 41446 cm2/mmol. Fluorescence (CH2Cl2): λmax = 580 nm. HR-ESI-MS (g/mol): Calcd. for C44H48N6: 660.3940, found: 660.3915.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

	x	y	z	Uiso*/Ueq
N1	0.4285 (2)	0.53184 (16)	0.5798 (2)	0.0526 (7)
C2	0.4847 (3)	0.57967 (17)	0.5085 (3)	0.0504 (7)
C3	0.4652 (3)	0.66661 (19)	0.5238 (3)	0.0550 (8)
H3	0.5045	0.7023	0.4744	0.066*
C4	0.3983 (3)	0.69750 (19)	0.5996 (3)	0.0546 (8)
H4	0.3625	0.6602	0.6494	0.066*
C5	0.3701 (3)	0.78186 (17)	0.6194 (3)	0.0476 (7)
C6	0.2997 (3)	0.80216 (18)	0.7090 (3)	0.0519 (8)
H6	0.2713	0.7604	0.7568	0.062*
C7	0.2687 (3)	0.87950 (19)	0.7326 (3)	0.0524 (8)
H7	0.2196	0.8901	0.7953	0.063*
C8	0.3084 (3)	0.94316 (17)	0.6651 (3)	0.0498 (7)
C9	0.3792 (3)	0.92395 (18)	0.5729 (3)	0.0548 (8)
H9	0.4075	0.9656	0.5248	0.066*
C10	0.4085 (3)	0.84511 (18)	0.5509 (3)	0.0504 (7)
H10	0.4561	0.8337	0.4873	0.060*
N11	0.2801 (3)	1.02172 (16)	0.6882 (3)	0.0671 (8)
C12	0.3545 (4)	1.08608 (19)	0.6484 (4)	0.0746 (11)
H12A	0.4442	1.0776	0.6846	0.112*
H12B	0.3270	1.1375	0.6779	0.112*
H12C	0.3424	1.0866	0.5557	0.112*
C13	0.2042 (3)	1.0400 (2)	0.7805 (4)	0.0731 (11)
H13A	0.1276	1.0068	0.7649	0.110*
H13B	0.1804	1.0968	0.7742	0.110*
H13C	0.2528	1.0289	0.8656	0.110*
C14	0.4417 (3)	0.45242 (19)	0.5724 (3)	0.0506 (7)
C15	0.3762 (3)	0.40327 (19)	0.6534 (3)	0.0556 (8)
H15	0.3938	0.3474	0.6585	0.067*
C16	0.2959 (3)	0.4313 (2)	0.7183 (3)	0.0564 (8)
H16	0.2803	0.4874	0.7116	0.068*
C17	0.2262 (3)	0.38681 (18)	0.8010 (3)	0.0490 (7)
C18	0.1360 (3)	0.4262 (2)	0.8539 (3)	0.0553 (8)
H18	0.1227	0.4818	0.8370	0.066*
C19	0.0648 (3)	0.3888 (2)	0.9297 (3)	0.0595 (8)
H19	0.0029	0.4184	0.9625	0.071*
C20	0.0826 (3)	0.3074 (2)	0.9590 (3)	0.0596 (9)
C21	0.1750 (3)	0.2668 (2)	0.9072 (3)	0.0590 (8)
H21	0.1897	0.2114	0.9253	0.071*
C22	0.2444 (3)	0.30536 (19)	0.8310 (3)	0.0546 (8)
H22	0.3064	0.2761	0.7977	0.065*
N23	0.0169 (3)	0.2693 (2)	1.0401 (4)	0.0948 (12)
C24	0.0001 (5)	0.1823 (3)	1.0311 (5)	0.1053 (17)
H24A	−0.0489	0.1683	0.9474	0.158*
H24B	−0.0452	0.1640	1.0967	0.158*
H24C	0.0831	0.1562	1.0433	0.158*
C25	−0.0672 (4)	0.3125 (3)	1.1036 (4)	0.0988 (16)
H25A	−0.0253	0.3612	1.1416	0.148*
H25B	−0.0904	0.2787	1.1702	0.148*
H25C	−0.1438	0.3271	1.0426	0.148*

	U11	U22	U33	U12	U13	U23
N1	0.0507 (14)	0.0585 (16)	0.0480 (14)	−0.0022 (12)	0.0079 (12)	−0.0034 (12)
C2	0.0549 (17)	0.0391 (16)	0.0507 (17)	−0.0038 (13)	−0.0061 (14)	0.0016 (13)
C3	0.0572 (18)	0.0496 (18)	0.0590 (19)	−0.0042 (14)	0.0131 (15)	0.0023 (15)
C4	0.0517 (17)	0.0487 (18)	0.0616 (19)	0.0010 (13)	0.0068 (15)	−0.0002 (15)
C5	0.0466 (15)	0.0420 (15)	0.0532 (17)	−0.0028 (12)	0.0071 (13)	−0.0003 (13)
C6	0.0524 (17)	0.0450 (17)	0.0604 (19)	−0.0010 (13)	0.0163 (15)	0.0080 (14)
C7	0.0548 (17)	0.0517 (17)	0.0539 (18)	0.0016 (14)	0.0189 (14)	−0.0023 (14)
C8	0.0513 (17)	0.0402 (16)	0.0555 (17)	0.0021 (13)	0.0045 (14)	−0.0014 (13)
C9	0.0589 (18)	0.0446 (17)	0.0617 (19)	−0.0071 (14)	0.0134 (15)	0.0078 (14)
C10	0.0514 (17)	0.0476 (17)	0.0551 (18)	−0.0031 (13)	0.0179 (14)	−0.0038 (14)
N11	0.081 (2)	0.0423 (15)	0.078 (2)	0.0051 (13)	0.0160 (17)	−0.0054 (14)
C12	0.097 (3)	0.0389 (18)	0.079 (2)	−0.0035 (17)	−0.006 (2)	0.0002 (16)
C13	0.068 (2)	0.063 (2)	0.083 (3)	0.0145 (17)	0.002 (2)	−0.0182 (19)
C14	0.0511 (16)	0.0507 (18)	0.0476 (16)	−0.0105 (13)	0.0033 (13)	0.0066 (14)
C15	0.0636 (19)	0.0481 (17)	0.0553 (18)	−0.0025 (15)	0.0119 (15)	0.0016 (14)
C16	0.0555 (18)	0.0558 (19)	0.0569 (19)	−0.0053 (15)	0.0086 (15)	−0.0011 (15)
C17	0.0479 (16)	0.0498 (17)	0.0484 (16)	−0.0038 (13)	0.0071 (13)	−0.0003 (13)
C18	0.0544 (18)	0.0520 (18)	0.0596 (19)	0.0074 (14)	0.0112 (15)	0.0000 (15)
C19	0.0494 (17)	0.071 (2)	0.061 (2)	0.0080 (15)	0.0173 (15)	−0.0014 (17)
C20	0.0519 (18)	0.073 (2)	0.0561 (19)	−0.0061 (16)	0.0153 (15)	0.0104 (17)
C21	0.067 (2)	0.0506 (18)	0.061 (2)	−0.0041 (15)	0.0174 (17)	0.0063 (15)
C22	0.0586 (18)	0.0529 (18)	0.0558 (18)	0.0003 (14)	0.0200 (15)	−0.0054 (14)
N23	0.089 (2)	0.107 (3)	0.101 (3)	−0.005 (2)	0.049 (2)	0.031 (2)
C24	0.091 (3)	0.110 (4)	0.114 (4)	−0.020 (3)	0.019 (3)	0.057 (3)
C25	0.062 (2)	0.168 (5)	0.074 (3)	−0.008 (3)	0.031 (2)	0.013 (3)

N1—C2	1.330 (4)	C13—H13C	0.9800
N1—C14	1.336 (4)	C14—C2i	1.392 (4)
C2—C14i	1.392 (4)	C14—C15	1.471 (4)
C2—C3	1.479 (4)	C15—C16	1.299 (4)
C3—C4	1.294 (4)	C15—H15	0.9500
C3—H3	0.9500	C16—C17	1.470 (4)
C4—C5	1.463 (4)	C16—H16	0.9500
C4—H4	0.9500	C17—C18	1.382 (4)
C5—C6	1.379 (4)	C17—C22	1.401 (4)
C5—C10	1.393 (4)	C18—C19	1.371 (4)
C6—C7	1.368 (4)	C18—H18	0.9500
C6—H6	0.9500	C19—C20	1.398 (5)
C7—C8	1.399 (4)	C19—H19	0.9500
C7—H7	0.9500	C20—N23	1.379 (4)
C8—N11	1.379 (4)	C20—C21	1.404 (5)
C8—C9	1.399 (4)	C21—C22	1.371 (4)
C9—C10	1.383 (4)	C21—H21	0.9500
C9—H9	0.9500	C22—H22	0.9500
C10—H10	0.9500	N23—C25	1.430 (6)
N11—C13	1.434 (5)	N23—C24	1.463 (6)
N11—C12	1.452 (4)	C24—H24A	0.9800
C12—H12A	0.9800	C24—H24B	0.9800
C12—H12B	0.9800	C24—H24C	0.9800
C12—H12C	0.9800	C25—H25A	0.9800
C13—H13A	0.9800	C25—H25B	0.9800
C13—H13B	0.9800	C25—H25C	0.9800
C2—N1—C14	119.6 (3)	N1—C14—C2i	119.9 (3)
N1—C2—C14i	120.5 (3)	N1—C14—C15	116.7 (3)
N1—C2—C3	115.7 (3)	C2i—C14—C15	123.5 (3)
C14i—C2—C3	123.8 (3)	C16—C15—C14	124.2 (3)
C4—C3—C2	124.6 (3)	C16—C15—H15	117.9
C4—C3—H3	117.7	C14—C15—H15	117.9
C2—C3—H3	117.7	C15—C16—C17	127.9 (3)
C3—C4—C5	129.1 (3)	C15—C16—H16	116.1
C3—C4—H4	115.5	C17—C16—H16	116.1
C5—C4—H4	115.5	C18—C17—C22	116.4 (3)
C6—C5—C10	116.2 (3)	C18—C17—C16	119.3 (3)
C6—C5—C4	119.7 (3)	C22—C17—C16	124.3 (3)
C10—C5—C4	124.1 (3)	C19—C18—C17	123.0 (3)
C7—C6—C5	123.2 (3)	C19—C18—H18	118.5
C7—C6—H6	118.4	C17—C18—H18	118.5
C5—C6—H6	118.4	C18—C19—C20	120.5 (3)
C6—C7—C8	120.6 (3)	C18—C19—H19	119.7
C6—C7—H7	119.7	C20—C19—H19	119.7
C8—C7—H7	119.7	N23—C20—C19	121.7 (3)
N11—C8—C9	121.0 (3)	N23—C20—C21	121.2 (3)
N11—C8—C7	121.8 (3)	C19—C20—C21	117.1 (3)
C9—C8—C7	117.2 (3)	C22—C21—C20	121.3 (3)
C10—C9—C8	120.8 (3)	C22—C21—H21	119.3
C10—C9—H9	119.6	C20—C21—H21	119.3
C8—C9—H9	119.6	C21—C22—C17	121.6 (3)
C9—C10—C5	122.0 (3)	C21—C22—H22	119.2
C9—C10—H10	119.0	C17—C22—H22	119.2
C5—C10—H10	119.0	C20—N23—C25	121.3 (4)
C8—N11—C13	120.2 (3)	C20—N23—C24	119.2 (4)
C8—N11—C12	119.7 (3)	C25—N23—C24	116.7 (4)
C13—N11—C12	117.8 (3)	N23—C24—H24A	109.5
N11—C12—H12A	109.5	N23—C24—H24B	109.5
N11—C12—H12B	109.5	H24A—C24—H24B	109.5
H12A—C12—H12B	109.5	N23—C24—H24C	109.5
N11—C12—H12C	109.5	H24A—C24—H24C	109.5
H12A—C12—H12C	109.5	H24B—C24—H24C	109.5
H12B—C12—H12C	109.5	N23—C25—H25A	109.5
N11—C13—H13A	109.5	N23—C25—H25B	109.5
N11—C13—H13B	109.5	H25A—C25—H25B	109.5
H13A—C13—H13B	109.5	N23—C25—H25C	109.5
N11—C13—H13C	109.5	H25A—C25—H25C	109.5
H13A—C13—H13C	109.5	H25B—C25—H25C	109.5
H13B—C13—H13C	109.5
C14—N1—C2—C14i	−0.8 (5)	C2—N1—C14—C2i	0.7 (5)
C14—N1—C2—C3	−179.7 (3)	C2—N1—C14—C15	−179.6 (3)
N1—C2—C3—C4	−0.3 (5)	N1—C14—C15—C16	8.6 (5)
C14i—C2—C3—C4	−179.2 (3)	C2i—C14—C15—C16	−171.8 (3)
C2—C3—C4—C5	−178.2 (3)	C14—C15—C16—C17	179.9 (3)
C3—C4—C5—C6	−177.7 (3)	C15—C16—C17—C18	−174.4 (3)
C3—C4—C5—C10	3.4 (5)	C15—C16—C17—C22	5.5 (5)
C10—C5—C6—C7	−0.6 (5)	C22—C17—C18—C19	−1.4 (5)
C4—C5—C6—C7	−179.5 (3)	C16—C17—C18—C19	178.5 (3)
C5—C6—C7—C8	−0.2 (5)	C17—C18—C19—C20	1.1 (5)
C6—C7—C8—N11	−179.0 (3)	C18—C19—C20—N23	176.6 (3)
C6—C7—C8—C9	0.6 (4)	C18—C19—C20—C21	−0.3 (5)
N11—C8—C9—C10	179.3 (3)	N23—C20—C21—C22	−177.1 (3)
C7—C8—C9—C10	−0.3 (5)	C19—C20—C21—C22	−0.2 (5)
C8—C9—C10—C5	−0.5 (5)	C20—C21—C22—C17	−0.2 (5)
C6—C5—C10—C9	0.9 (4)	C18—C17—C22—C21	0.9 (5)
C4—C5—C10—C9	179.8 (3)	C16—C17—C22—C21	−178.9 (3)
C9—C8—N11—C13	178.2 (3)	C19—C20—N23—C25	−3.6 (6)
C7—C8—N11—C13	−2.2 (5)	C21—C20—N23—C25	173.2 (4)
C9—C8—N11—C12	−19.6 (5)	C19—C20—N23—C24	156.6 (4)
C7—C8—N11—C12	160.1 (3)	C21—C20—N23—C24	−26.6 (6)