Zwitterionic form of tris­({[5-(4-meth­oxy­phenyl­azo)salicyl­idene]amino}­eth­yl)amine

Sadegh Salehzadeh; Mahsa Mahdavian; Mehdi Khalaj

doi:10.1107/S1600536811004405

. 2011 Feb 12;67(Pt 3):o606. doi: 10.1107/S1600536811004405

Zwitterionic form of tris({[5-(4-methoxyphenylazo)salicylidene]amino}ethyl)amine

Sadegh Salehzadeh ^a,^*, Mahsa Mahdavian ^a, Mehdi Khalaj ^b

PMCID: PMC3052149 PMID: 21522363

Abstract

The title compound (systematic name: 2-{[2-(bis{2-[({2-hydroxy-5-[(4-methoxyphenyl)diazenyl]phenyl}methylidene)amino]ethyl}amino)ethyl]azaniumylidenemethyl}-4-[(4-methoxyphenyl)diazenyl]phenolate), C₄₈H₄₈N₁₀O₆, exists as a zwitterion in the solid state. The three arms of the tripodal molecule are located close to each other and an intramolecular hydrogen bond occurs in each arm (O—H⋯N in two arms and N—H⋯O in the zwitterionic arm). The dihedral angles between the aromatic rings in the three arms are 16.36 (14), 23.94 (14) and, for the zwitterionic arm, 37.14 (14)°. In the crystal, a weak intermoleclar N—H⋯O hydrogen bond occurs.

Related literature

For tripodal Schiff base ligands, see: Kanesato et al. (2000 ▶) and for azo compounds, see: Butcher et al. (2005 ▶). For further synthetic details, see: Dinçalp et al. (2007 ▶).

Experimental

Crystal data

C₄₈H₄₈N₁₀O₆
M _r = 860.96
Triclinic,
a = 10.5613 (9) Å
b = 12.1234 (5) Å
c = 17.2107 (9) Å
α = 86.418 (3)°
β = 89.308 (2)°
γ = 88.084 (3)°
V = 2198.0 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 150 K
0.22 × 0.20 × 0.16 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SORTAV; Blessing, 1995 ▶) T _min = 0.827, T _max = 0.990
19855 measured reflections
9781 independent reflections
4152 reflections with I > 2σ(I)
R _int = 0.071

Refinement

R[F ² > 2σ(F ²)] = 0.062
wR(F ²) = 0.187
S = 0.99
9781 reflections
589 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: COLLECT (Nonius, 2002 ▶); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 ▶); data reduction: DENZO-SMN; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXTL (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811004405/hb5798sup1.cif

e-67-0o606-sup1.cif^{(29.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811004405/hb5798Isup2.hkl

e-67-0o606-Isup2.hkl^{(478.3KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯N4	1.07 (4)	1.58 (4)	2.543 (3)	146 (3)
O1—H1⋯N2	0.98 (4)	1.61 (4)	2.534 (3)	157 (3)
N3—H2⋯O2	1.02 (4)	1.71 (4)	2.585 (3)	142 (3)
N3—H2⋯O2ⁱ	1.02 (4)	2.48 (4)	3.155 (3)	123 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

We are grateful to Bu-Ali Sina University for financial support.

supplementary crystallographic information

Comment

Herein, we report the synthesis and X-ray crystal structure of the title compound, (I), (Fig. 1), a tripodal Schiff base ligand containing three azo groups. For tripodal Schiff base ligands see: Kanesato et al. (2000) and for azo compounds see: Butcher et al. (2005).

The title compound adopts a cage-like conformation in the solid state. The geometry around the bridghead N atom of the compound is approximately pyramidal, since the angles C1–N1–C33, C1–N1–C17 and C33–N1–C17 have values of 112.3 (2), 113.5 (2) and 112.8 (2)°, respectively. The average of N═N bond lengths[1.25 (3) Å] is in the expected range and is in good agreement with values found in other similar compounds. Interestingly the hydrogen atom of one of three OH groups has transferred to one of three imine groups through intramolecular hydrogen bonding producing a zwitterionic compound. Three arms of tripodal ligand are located close to each other and in all of them there is an intramolecularhydrogen bonding (table 1).

Experimental

Azo dye (5-(4-methoxyphenylazo)salicylaldehyde) was synthesized according to the literature procedure (Dinçalp et al., 2007). Then to a solution of above aldehyde (3 mmol) in ethanol (70 ml) was added tren (1 mmol) in the same solvent (10 ml) (see Scheme I). The solution was stirred for 12 h at 40°C. The resulting orange precipitate was filtered and dried in vacuum. Orange blocks of (I) were obtained by slow evaporation from a acetonitril solution at room temperature after 24 h.