organic compounds
Crystal data
associate by hydrogen bonds to 4-acetylpyridine groups at the
four corners of TCPP. The laterally extended 1:4 porphyrin–
4-acetylpyridine aggregates assemble into open-channel voids
with very wide channels (Fig. 4) filled with uncoordinated
solvent (Lipstman et al., 2006). In spite of the large inter-
porphyrin pores, characterized by a van der Waals width of
3
˚
V = 3380.5 (2) A
Z = 2
C64H66B4N4O8Á2C6H5NO2
Mr = 1308.67
Monoclinic, P21=c
Mo Kꢃ radiation
ꢄ = 0.09 mmÀ1
T = 110 (2) K
0.55 Â 0.20 Â 0.15 mm
˚
a = 18.6511 (7) A
˚
b = 9.2969 (3) A
˚
c = 20.7606 (9) A
ꢂ = 110.1016 (13)ꢁ
˚
about 17 A, these layers do not interweave in this structure.
Rather, they are stacked one on top of the other in a partly
offset manner, giving rise to tunnels of approximate width
Data collection
Nonius KappaCCD diffractometer
23064 measured reflections
6333 independent reflections
3223 reflections with I > 2ꢅ(I)
Rint = 0.089
˚
14 A (accessible to the solvent) that propagate through the
crystal perpendicular to the layers.
In summary, we have described the synthetic route to the
title compound, (I), and to the tetraboronic acid porphyrin
analog that represents a new scaffold for the construction of
porphyrin-based supramolecular assemblies. Another focus is
on the interesting clathrate-type organization observed in
tetraphenylporphyrin compounds extended in the four lateral
directions by additional substituents without coordination or
hydrogen-bonding functions. Such interporphyrin layered
arrangements sustain large voids primarily by dispersion
forces and are rarely observed with such expanded tetra-
phenylporphyrin scaffolds.
Refinement
R[F2 > 2ꢅ(F2)] = 0.064
wR(F2) = 0.179
S = 0.97
446 parameters
H-atom parameteÀrs3 constrained
˚
Áꢆmax = 0.33 e A
À3
˚
6333 reflections
Áꢆmin = À0.24 e A
H atoms bound to C atoms were located in calculated positions
and constrained to ride on their parent atoms, with C—H = 0.95
˚
(aryl), 0.98 (methyl) or 0.99 A (methylene) and Uiso(H) = 1.2Ueq(aryl
and methylene) and 1.5Ueq(methyl). The two N-bound pyrrole H
atoms are disordered between the four N-atom sites. Some of the B
atoms exhibit minor conformational disorder. Large-amplitude
anisotropic displacement parameters characterize the nitrobenzene
solvent species.
Experimental
Data collection: COLLECT (Nonius, 1999); cell refinement:
DENZO (Otwinowski & Minor, 1997); data reduction: DENZO;
program(s) used to solve structure: SIR97 (Altomare et al., 1994);
program(s) used to refine structure: SHELXL97 (Sheldrick, 2008);
molecular graphics: ORTEPIII (Burnett & Johnson, 1996) and
Mercury (Macrae et al., 2006); software used to prepare material for
publication: SHELXL97.
The synthesis of the title compound proceeded in two steps, using
commercially available reagents, following the procedures reported
by Lindsey & Wagner (1989) and Hyslop et al. (1998). First, a mixture
of 4-formylphenylboronic acid (2.35 g) and 2,2-dimethylpropane-1,3-
diol (1.80 g) in dry tetrahydrofuran (THF; 25 ml) was stirred for 3 h.
After evaporation of the solvent under reduced pressure, the
resulting residue was dissolved in CH2Cl2 (20 ml), washed several
times with water, dried with anhydrous sodium sulfate and concen-
trated in a vaccum. The residue was added to hexane with shaking
(50 ml) and the resulting suspension was concentrated under vacuum
to give the desired white solid product 2-(4-formylphenyl)-5,5-
dimethyl-1,3,2-dioxaborinane (yield 3.54 g, 90%). In the next step,
the title compound was synthesized by condensing the product
(2.51 g) from the first step dissolved in CH2Cl2 (1000 ml) with pyrrole
(0.8 ml) (purged with nitrogen gas). To this, 0.9 M BF3–etherate
(10 ml) was added under nitrogen, followed by addition of p-chloranil
(2.12 g). After the normal work-up procedure (Lindsey & Wagner,
1989), the raw product was passed through a silica-gel column with
a 4% acetone-in-chloroform eluent. Recrystallization from a 1:3
chloroform–methanol mixture, containing a few drops of nitro-
benzene, afforded pure (I) (yield 0.59 g, 16%).1H NMR (CDCl3): ꢁ
8.82 (s, 8H), 8.18 (s, 16H), 3.93 (s, 16H), 1.16 (s, 24H), À2.85 (s, 2H).
FAB mass spectrum (m/z) for C64H66B4N4O8: found 1058, calculated
1058.3. Conversion of (I) to the corresponding tetraboronic acid
(deprotection of the tetra-ester) was made by treatment with a
solution of KOH in a mixture of THF and methanol at 363 K for 2 d.
The crude product was washed with 10% HCl, filtered and neutra-
lized with a 10% solution of Et3N in methanol and pyridine. The final
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SF3072). Services for accessing these data are
described at the back of the journal.
References
Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C.,
Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.
Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak
Ridge National Laboratory, Tennessee, USA.
Byrn, M. P., Curtis, C. J., Hsiou, Y., Khan, S. I., Sawin, P. A., Tendick, S. K.,
Terzis, A. & Strouse, C. E. (1993). J. Am. Chem. Soc. 115, 9480–9497.
Goldberg, I. (2005). Chem. Commun. pp. 1243–1254.
Hata, H., Shinokubo, H. & Osuka, A. (2005). J. Am. Chem. Soc. 127, 8264–
8265.
Hyslop, A. G., Kellet, M. A., Iovine, P. M. & Therien, M. J. (1998). J. Am.
Chem. Soc. 120, 12676–12677.
Krishna Kumar, R., Balasubramanian, S. & Goldberg, I. (1998). Inorg. Chem.
37, 541–552.
Lindsey, J. S. & Wagner, R. W. (1989). J. Org. Chem. 54, 828–836.
Lipstman, S., Muniappan, S., George, S. & Goldberg, I. (2006). CrystEng-
Comm, 8, 601–607.
Lipstman, S., Muniappan, S., George, S. & Goldberg, I. (2007). Dalton Trans.
pp. 3273–3281.
Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor,
R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457.
Nonius (1999). COLLECT. Nonius BV, Delft, The Netherlands.
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276,
Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M.
Sweet, pp. 307–326. New York: Academic Press.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
Suslick, K. N., Bhyrappa, P., Chou, J.-H., Kosal, M. E., Nagakaki, S., Smithenry,
D. W. & Wilson, S. R. (2005). Acc. Chem. Res. 38, 283–291.
1
product was washed with water and dried. H NMR (DMSO-d6):
ꢁ 8.77 (s, 8H), 8.32 (s, 8H), 8.15 (q, 16H, J = 8.2 Hz, J = 2.1 Hz), À2.98
(s, 2H). MALDI–TOF mass spectrum (m/z) for C44H34B4N4O8: found
791.3, calculated 790.02. Compound (I) crystallized as long thin red
needles which exhibited relatively weak diffraction. Repeated
attempts to crystallize TBPP has thus far resulted in solids of very
poor crystallinity.
ꢀ
Acta Cryst. (2008). C64, o177–o179
Muniappan et al. C64H66B4N4O8Á2C6H5NO2 o179