Tetrakis[2-(benzylaminocarbonyl)phenoxymethyl]methane

The title compound, C61H56N4O8, is arranged with all four salicylamide arms disposed in a circular fashion. Each arm has a similar conformation and they are extended so that their terminal groups can fold back. The four carbonyl O atoms are located on the outside of the molecule. The structure is stabilized by intra- and intermolecular N—H⋯O hydrogen-bonding interactions.

The title compound, C 61 H 56 N 4 O 8 , is arranged with all four salicylamide arms disposed in a circular fashion. Each arm has a similar conformation and they are extended so that their terminal groups can fold back. The four carbonyl O atoms are located on the outside of the molecule. The structure is stabilized by intra-and intermolecular N-HÁ Á ÁO hydrogenbonding interactions.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2625).

S1. Comment
In the last decade, synthetic studies on salicylamide delived ligands have been carried out because of their attractive sensitization of lanthanide luminescence as well as construction of novel metal-organic frameworks (Zhang et al., 2002;Tang et al., 2005) we are systematically studying the structure and the photophysical properties of complexing salicylamide ligands of capable of sensitizing Eu(III) and Tb(III) emission recently. So far, some intriguing supramolecular complexes based on salicylamide derivatives have been reported Song et al., 2008). However, the tetrapodal ligand featuring salicylamide pendant arms, which is analogues of the ligands studies above, is still unprecedented. In view of this, we report here the synthesis and crystal structure of the title compound (I) which is a part of our studies.
The molecular structure of the title compound (I) is shown in Fig. 1. All bond lengths and angles in (I) are generally within normal ranges (Allen et al., 1987). Four benzylsalicylamide arms are linked together by the quarternary carbon atom at the tetrahedry position and are severely twisted with a ca 65° dihedral angle between phenyl rings. The amide hydrogen atoms (H1, H2, H3 and H4) are hydrogen bonded to the ether oxygen atoms (O1, O3, O5 and O7) to provide four hydrogen bonded six-membered rings. It is no doubt to note that the robust intramolecular hydrogen bond have a template effect and participate in the stabilization of the complete structure (Table 1). Interestingly, the title compound was arranged with all four salicylamide arms in a circular fashion and each salicylamide arm had a similar conformation and the arm is so long that their terminal groups can "fold back". Four oxygen atoms of the carbonyl groups of the compound, namely, O2, O4, O6 and, O8, are located in the outer part of the whole molecule.

S2. Experimental
The title compound was synthesized by the following method. To a solution of pentaerythritol benzenesulfonate (2.32 g, 3.3 mmol) (Farber et al.,1974) in dry DMF was added K 2 CO 3 (0.69 g, 5 mmol) and the mixture stirred and heated for 10 min, N-benzylsalicylamide (3.40 g, 15 mmol) (Jiri et al.,1994) in 50 ml DMF was added dropwise in 30 min and the resulting solution stirred and heated to reflux for 12 h. After cooling down, inorganic salts was separated by filtration and the solvent was removed from the filtrate under reduced pressure. The crude product was purified by chromatography on silica, gradient elution from petroleum to 10:1 petroleum-ethyl acetate to give a white powder. Colourless single crystals were grown from methanol and ethyl acetate mixed solution (v:v =1:5) with slow evaporation at room temperature. The crystals were isolated, washed three times with ethyl acetate and dried in vacuum desiccator using anhydrous CaCl 2 (yield 87.4%). Analysis found (%) : C 75.59, H 5.59, N 5.18; calculated for C 61 H 56 N 4 O 8 : C 75.29, H 5.61, N 5.20.

S3. Refinement
All H atoms were positioned geometrically and allowed to ride on their parent atoms, with C-H = 0.95 and 0.99 Å and N-H =distance of 0.88 Å, with U iso (H) = 1.2U eq (C, N).  ORTEP plot of the title compound, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. For the sake of clarity, H atoms have been omitted.

Tetrakis[2-(benzylaminocarbonyl)phenoxymethyl]methane
where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.33 e Å −3 Δρ min = −0.28 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0058 (9) Special details 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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.