9-{4-[(E)-2-(4,6-Dimethyl-1,3,5-triazin-2-yl)ethen­yl]phen­yl}-9H-carbazole

Chang-Lin Liu; Gang Xue; Yue-Zhi Cui; Tian-Duo Li; Seik Weng Ng

doi:10.1107/S1600536809030359

. 2009 Aug 8;65(Pt 9):o2095. doi: 10.1107/S1600536809030359

9-{4-[(E)-2-(4,6-Dimethyl-1,3,5-triazin-2-yl)ethenyl]phenyl}-9H-carbazole

Chang-Lin Liu ^a, Gang Xue ^b, Yue-Zhi Cui ^a,^*, Tian-Duo Li ^a, Seik Weng Ng ^c

PMCID: PMC2970030 PMID: 21577511

Abstract

In the crystal structure of the title compound, C₂₅H₂₀N₄, the triazinyl ring is nearly coplanar with the planar (r.m.s. deviation = 0.028 Å) phenylethenyl unit, the twist being only 5.8 (2)°; however, the planar carbazolyl unit (r.m.s. deviation = 0.008 Å) is twisted by 47.8 (1)° with respect to the phenylethenyl unit. The nonplanar nature of the molecule explains the phenomenon of light emission at short wavelengths in the solid state but at long wavelengths in solution.

Related literature

For background literature on donor–π-acceptor chromophores, see: Cui et al. (2003 ▶, 2004 ▶); Kannan et al. (2004 ▶); Maury & Bozec (2005 ▶); Zhong et al. (2008 ▶).

Experimental

Crystal data

C₂₅H₂₀N₄
M _r = 376.45
Orthorhombic,
a = 8.0415 (8) Å
b = 15.716 (2) Å
c = 16.098 (1) Å
V = 2034.4 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 293 K
0.42 × 0.28 × 0.16 mm

Data collection

Siemens P4 four-circle diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.901, T _max = 0.988
2991 measured reflections
2291 independent reflections
1288 reflections with I > 2σ(I)
R _int = 0.026
3 standard reflections every 97 reflections intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.055
wR(F ²) = 0.160
S = 1.00
2291 reflections
265 parameters
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: XSCANS (Siemens, 1996 ▶); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809030359/bt5017sup1.cif

e-65-o2095-sup1.cif^{(20.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809030359/bt5017Isup2.hkl

e-65-o2095-Isup2.hkl^{(112.6KB, hkl)}

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

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 20676074) and the Foundation for Excellent Middle/Young Scientists of Shandong Province (grant No. 2005BS11011).

supplementary crystallographic information

Comment

s-Triazine, which has a conjugated structure is commonly derivatized in the design of chromophores that display specific physical properties (Cui et al., 2003; Maury et al., 2005; Zhong et al., 2008), particularly two-photon absorption (Cui et al., 2004; Kannan et al., 2004). The title compound (Fig. 1, Scheme 1) exemplifies a donor-π-acceptor compound with a carbazolyl donor and an s-triazinyl acceptor. It emits blue light in solid state and yellow-green light in solution. However, this property is unusual as most compounds show a bathochromic shift of fluorescence in solid state relative to their emission in solution.

An intramolecular charge transfer (ICT) axis runs from atom N2 to atom N4. The phenylethenyl unit is almost coplanar with the triazinyl ring. However, the carbazolyl unit is severely twisted with respect to the phenylethenyl and triazinyl units, so that conjugation is poor. Accordingly, such a poorly-conjugated molecule can only emit at a short wavelength (in the solid state) whereas in solution, the molecule is probably freed from strain and can achieve planarity. Consequently, it emits at longer wavelengths. The molecules are packed such that the axes of one half the number molecules are aligned in one direction whereas those of the other half are aligned approximately perpendicular to it (Fig. 2).

Experimental

4-N-Carbazolylbenzaldehyde (2.03 g, 7.5 mmol) in methanol (30 ml) was added to 2,4,6-trimethyl-s-triazine (1.85 g, 15 mmol) and potassium hydroxide (0.5 g) in methanol (50 ml). The mixture was heated for 24 h. The solvent was removed and the residue was purified by column chromatography on silica gel by using benzene/ethanol (10/1) as eluent. Crystals were obtained by recrystallization from a benzene/ethanol solution of the compound.