A new crystal phase of N,N,N′,N′-tetra­phenyl-1,1′-biphenyl-4,4′-diamine

Xiangfeng Shao; Kenshiro Asahi; Takayoshi Yamauchi; Toyonari Sugimoto; Motoo Shiro

doi:10.1107/S1600536809016389

. 2009 May 7;65(Pt 6):o1224. doi: 10.1107/S1600536809016389

A new crystal phase of N,N,N′,N′-tetraphenyl-1,1′-biphenyl-4,4′-diamine

Xiangfeng Shao ^a, Kenshiro Asahi ^a, Takayoshi Yamauchi ^a, Toyonari Sugimoto ^a,^*, Motoo Shiro ^b

PMCID: PMC2969720 PMID: 21583092

Abstract

The complete molecule of the title compound, C₃₆H₂₈N₂, is generated by a crystallographic centre of inversion. The biphenyl unit is forced by symmetry to be essentially flat (r.m.s. deviation = 0.008 Å); the dihedral angles between it and the two terminal phenyl rings are 69.39 (5) and 59.53 (5)°.

Related literature

For the electronic properties of semiconductors based triarylamines, see, for example: Kennedy et al. (2002 ▶); Shirota (2000 ▶, 2005 ▶); Song et al. (2006 ▶). For the preparation of triarylamine, see: Hartwig (1999 ▶). For related structures, see: Kennedy et al. (2002 ▶); Low et al. (2004 ▶); Zhang et al. (2004 ▶, 2006 ▶).

Experimental

Crystal data

C₃₆H₂₈N₂
M _r = 488.63
Monoclinic,
a = 9.6846 (2) Å
b = 14.2661 (4) Å
c = 9.7946 (2) Å
β = 107.0521 (15)°
V = 1293.75 (5) Å³
Z = 2
Cu Kα radiation
μ = 0.56 mm⁻¹
T = 173 K
0.15 × 0.14 × 0.11 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.885, T _max = 0.941
14609 measured reflections
2362 independent reflections
1956 reflections with F ² > 2σ(F ²)
R _int = 0.045

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.119
S = 1.07
2362 reflections
174 parameters
H-atom parameters constrained
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 1998 ▶); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2007 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPII (Johnson, 1976 ▶); software used to prepare material for publication: CrystalStructure.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809016389/bq2132sup1.cif

e-65-o1224-sup1.cif^{(20.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809016389/bq2132Isup2.hkl

e-65-o1224-Isup2.hkl^{(116.1KB, hkl)}

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

Acknowledgments

This work was supported by a Grant-in-Aid for Scientific Research (grant No. 19350073) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

supplementary crystallographic information

Comment

Triarylamine-based organic semiconductors have been intensively investigated as hole transport materials for electro-optic devices (Kennedy et al., 2002; Shirota, 2000; Shirota, 2005). Recently, the organic field-effect transistor (OFET) based on a cyclic triphenylamine has been reported, which shows the relatively good mobility and high on/off ratio (Song et al., 2006). The title compound, N,N,N',N'-tetraphenyl-1,1'-biphenyl-4,4'-diamine (I), has been synthesized by coupling of two triphenylamine molecules using a copper catalyst (Ullman coupling) and also using methanesulfonic acid as catalyst in the yield of 10% (Zhang et al., 2006). We have synthesized compound (I) from the coupling of 4,4'-dibromobiphenyl and diphenylamine using a palladium catalyst in the yield of 71% (Hartwig, 1999). The crystal structure of compound (I) has been reported (Zhang et al., 2006), where the biphenyl part of the molecule is highly twisted with a dihedral angle of 32.9 (4)°. Herein, we report another crystal phase of compound (I).

The molecule (I) possesses a inversion center, thus the biphenyl moiety of the molecule shows a completely flat conformation with an average deviation of 0.0079Å (Fig. 1). The other fused rings make 69.39 (5)° and 59.53 (5)° dihedral angles with this flat biphenyl moiety. The N atom displays an almost trigonal geometry with slight distortion of the N—C bond lengths and C—N—C bond angles. The angle sums around the N atom is ca 360°. The molecular geometry of (I) is quite different from the previously reported one (Zhang et al., 2006), and also different from those of the related biphenyl-diamine compounds (Kennedy et al., 2002, Low et al., 2004; Zhang et al., 2004). The molecular packing pattern in the present crystal is also different from the reported one (Zhang et al., 2006), and a herringbone-like packing motif governed by the van der Waals interactions is observed (Fig. 2).

Experimental

A suspension of 4,4'-dibromobiphenyl (3.1 g, 10 mmol), diphenylamine (3.9 g, 21 mmol) and sodium t-butoxide (2.3 g, 24 mmol) in xylene (20 ml) was refluxed in the presence of palladium(II) acetate (4.4 mg, 0.020 mmol) and triphenylphosphine (42 mg, 0.016 mmol) for 5 h under an argon atmosphere. After removing the solvent in vacuum, the residue was separated by column chromatography on silica gel using benzene as eluent to afford the title compound in the yield of 71%. The single crystals of (I) suitable for the X-ray crystallographic analysis were obtained by recrystallization from benzene/hexane as colorless blocks.