5,10,15,20-Tetrakis(4-acetyloxyphenyl)porphyrin including an unknown solvate

Molecules of the title compound, C52H38N4O8, are located on an inversion center so that the asymmetric cell contains one half of the molecule. The macrocycle exhibits a ruffled conformation with a maximum deviation of 0.16 Å for the 24 macrocycle atoms: the dihedral angle between adjacent five-membered rings is 5.13 (19)°. The benzene rings are rotated by 70.25 (19)° with respect to their adjacent protonated five-membered rings, and by 65.56 (19)° with respect to the unprotonated rings. The porphyrin conformation is supported by bifurcated N—H⋯(N,N) hydrogen bonds. The structure contained poorly resolved solvent molecules in voids of volume 217 Å3 per unit cell. The latter were treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]. As the solvent could not be identified exactly, it was not included in the calculation of the overall formula weight, density and absorption coefficient.


N. Sobral Comment
This work is part of a project of synthesizing porphyrins and porphyrin percursors (Paixão, Matos Beja et al., 2002;Paixão, Ramos Silva et al., 2002;Paixão et al., 2003;Ramos Silva et al., 2002a,b;Sobral et al., 2001a,b). Our aim is to use the tremendous potential for the manifold applications of porphyrins and obtain molecular magnets (Zhang et al., 2010), liquid crystals (Eichhorn, 2000), multi-porous materials for CO 2 sequestering and possibly some properties combined. In the title compound, Fig. 1 ,5,10,15,oxy]-phenylporphyrin, the porphyrin moiety shows a non planar ruffled conformation. The phenyl rings are rotated with respect to the porphyrin ring. The angle between the least-squares plane containing the porphyrin core and the least-squares plane of the phenyl ring C11-C16 is 65.29 (14)° [74.18 (13)° for C19-C24]. Intramolecular N-H···N hydrogen bonds are present. The molecules pile in columns along the a axis. There are solvent acessible voids in the crystal structure that accomodate solvent molecules in a very disordered way; these solvent molecules were not included in the calculation of the overall formula weight, density and absorption coefficient.

Experimental
All reagents were used as purchased, except pyrrole that was distillated under reduced pressure. The tetrakys-(pheny-4acetate)-21H,22H-porphine was synthesized by the method of Rothemund/Adler/Long [1-2]. The aldehyde 4-formylphenyl acetate (1 g, 6.1 mmol) was added to propionic acid (150 ml). The solution was placed to reflux and then pyrrole (0.5 ml, 7.207 mmol) was added drop wise during 10 minutes. The solution was left at 120 C for 4 h. The solvent was then evaporated and the crude, dissolved in dichloromethane, was washed with aqueous NaHCO3 and distilled water and dried with Na2SO4 anhydrous. The final porphyrin tetrakys-(pheny-4-acetate)-21H,22H-porphine was obtained after purification by column chromatography in silica/dichloromethane. Recrystallization in dichloromethane/hexane gives the purple crystals of tetrakys-(pheny-4-acetate)-21H,22H-porphine (yield of 5% relatively to pyrrole). HPLC/MS showed a single signal corresponding to the expected molecular ion m/z 847.

Refinement
H atoms bound to C atoms were placed at calculated positions and were treated as riding on the parent atoms with C-H = 0.93 Å (aromatic) and with U iso (H) = 1.2 U eq (C). In a final difference Fourier map highly disordered electron density occupying one cavity of ca 215 Å3 each was observed. This residual electron density was difficult to model and therefore, the SQUEEZE routine in PLATON (Spek, 2009) was used to eliminate this contribution of the electron density in the solvent region from the intensity data. The solvent-free model was employed for the final refinement. One of the methylcarbonyloxy terminal groups shows signs of disorder, possibly occupying two or more sites but such disorder could not be resolved in the present experiment. The solvent molecules were not included in the calculation of the overall   Packing of the molecules in the unit cell showing the H-bonds as dashed lines. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.040 Δρ max = 0.98 e Å −3 Δρ min = −0.51 e Å −3

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq N1 0.7700 (