organic compounds
N,N′-Dibenzyl-2,2′-[(1,3,4-oxadiazole-2,5-diyl)bis(o-phenyleneoxy)]diacetamide
aCollege of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, People's Republic of China
*Correspondence e-mail: tangn@lzu.edu.cn
The compound, C32H28N4O5, which was synthesized by the reaction of 2,5-bis(2-hydroxylphenyl)-1,3,4-oxadiazole with N-benzyl-2-chloroacetamide, lies on a twofold rotation axis which passes through the mid-point of the N—N bond and the O atom of the oxadiazole unit. The phenylene and oxadiazole rings are almost coplanar [dihedral angle 1.67 (5)°]. The structure is stabilized by intramolecular N—H⋯O and N—H⋯N hydrogen bonds.
Related literature
For the biological and physical properties of 1,3,4-oxadiazole derivatives, see Gómez-Saiz et al. (2002); Wen et al. (2003); Kuo et al. (2006). For literature on metal complexes, see Dong et al. (2003); Zhou et al. (1996).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: APEX2 (Bruker, 2001); cell SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536808033904/ng2497sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808033904/ng2497Isup2.hkl
To 2,5-bis[2'-hydroxyl-phenyl]-1,3,4-oxadiazole (Zhou et al., 1996) (1.78 g, 7 mmol) in DMF (80 ml) was added sodium hydroxide (0.56 g, 14 mmol). The mixture was heated to 353 K and stirred for about 1 h. A solution of N-benzyl-2-chloroacetamide (2.94 g, 16 mmol) and potassium iodide (0.83 g, 5 mmol) in DMF (20 ml) was then added dropwise at a constant rate over 1 h. The reaction mixture was stirred at ca 353 K for an additional 48 h. The solvent was removed under vacuum, and then the residue was treated with water (100 ml). The precipitate was collected by filtration and washed with water (100 ml), then twice recrystallized from methanol to give colourless block crystals. 1H NMR (400M Hz; CDCl3, δ, p.p.m): 9.19 (t, 2H, N—H, J = 6 Hz), 8.04 (d, 2H, Ar—H, J = 8 Hz), 7.58 (t, 2H, Ar—H, J = 8 Hz), 7.24–7.15 (m, 12H, Ar—H), 7.06 (d, 2H, Ar—H, J = 8 Hz), 4.72 (s, 4H, O—CH2), 4.32 (d, 4H, Ar—CH2—N, J= 6 Hz); Yield 2.30 g (60%); m.p. 462–464 K; elemental analysis, calculated for C32H28N4O5, C 70.06, H 5.14, N 10.21%; found: C 70.18, H 5.02, N 10.22%. Colourless single crystals suitable for an X-ray diffraction study were obtained by slow evaporation of the methanol solvent at room temperature over a period of 5 d.
All H atoms were initially located in a difference Fourier map and refined freely along with an isotropic displacement parameter. H atoms were positioned geometrically and treated as riding, with C—H = 0.93 and 0.97%A, N—H = 0.86%A,and Uiso(H) = 1.2Ueq(C,N).
Data collection: APEX2 (Bruker, 2001); cell
SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. The structure of the title compound, showing 20% probability displacement ellipsoids and the atom-labelling scheme. The intramolecular hydrogen bonds are shown as dashed lines. |
C32H28N4O5 | F(000) = 1152 |
Mr = 548.58 | Dx = 1.313 Mg m−3 |
Monoclinic, C2/c | Melting point: 462 K |
Hall symbol: -C2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 17.0619 (15) Å | Cell parameters from 3319 reflections |
b = 15.2601 (15) Å | θ = 2.4–27.5° |
c = 10.6555 (9) Å | µ = 0.09 mm−1 |
β = 90.611 (5)° | T = 293 K |
V = 2774.2 (4) Å3 | Block, colourless |
Z = 4 | 0.53 × 0.40 × 0.30 mm |
Bruker APEXII diffractometer | 2335 reflections with I > 2σ(I) |
Radiation source: sealed tube | Rint = 0.022 |
Graphite monochromator | θmax = 26.5°, θmin = 1.8° |
ϕ and ω scans | h = −21→20 |
7913 measured reflections | k = −12→19 |
2880 independent reflections | l = −13→12 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.041 | H-atom parameters constrained |
wR(F2) = 0.158 | w = 1/[σ2(Fo2) + (0.1P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.17 | (Δ/σ)max = 0.001 |
2880 reflections | Δρmax = 0.18 e Å−3 |
187 parameters | Δρmin = −0.13 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0054 (10) |
C32H28N4O5 | V = 2774.2 (4) Å3 |
Mr = 548.58 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 17.0619 (15) Å | µ = 0.09 mm−1 |
b = 15.2601 (15) Å | T = 293 K |
c = 10.6555 (9) Å | 0.53 × 0.40 × 0.30 mm |
β = 90.611 (5)° |
Bruker APEXII diffractometer | 2335 reflections with I > 2σ(I) |
7913 measured reflections | Rint = 0.022 |
2880 independent reflections |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.158 | H-atom parameters constrained |
S = 1.17 | Δρmax = 0.18 e Å−3 |
2880 reflections | Δρmin = −0.13 e Å−3 |
187 parameters |
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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.5000 | 1.06829 (8) | 0.7500 | 0.0488 (3) | |
O2 | 0.37163 (7) | 0.91715 (7) | 0.50427 (11) | 0.0724 (4) | |
O3 | 0.32801 (7) | 0.70855 (8) | 0.38437 (12) | 0.0822 (4) | |
N1 | 0.47305 (7) | 0.93150 (7) | 0.69949 (10) | 0.0494 (3) | |
N2 | 0.41511 (7) | 0.75799 (8) | 0.52944 (11) | 0.0586 (3) | |
H2A | 0.4317 | 0.8025 | 0.5714 | 0.070* | |
C1 | 0.45891 (7) | 1.01308 (8) | 0.67330 (11) | 0.0443 (3) | |
C2 | 0.40733 (7) | 1.05489 (9) | 0.58052 (11) | 0.0466 (3) | |
C3 | 0.40137 (9) | 1.14557 (10) | 0.57514 (13) | 0.0580 (4) | |
H3A | 0.4307 | 1.1796 | 0.6308 | 0.070* | |
C4 | 0.35278 (9) | 1.18603 (10) | 0.48861 (15) | 0.0677 (4) | |
H4A | 0.3493 | 1.2468 | 0.4865 | 0.081* | |
C5 | 0.30953 (9) | 1.13641 (11) | 0.40562 (15) | 0.0650 (4) | |
H5A | 0.2772 | 1.1639 | 0.3469 | 0.078* | |
C6 | 0.31367 (8) | 1.04601 (10) | 0.40866 (14) | 0.0582 (4) | |
H6A | 0.2839 | 1.0127 | 0.3528 | 0.070* | |
C7 | 0.36253 (7) | 1.00528 (9) | 0.49553 (11) | 0.0496 (3) | |
C8 | 0.32734 (8) | 0.86010 (9) | 0.42649 (13) | 0.0560 (4) | |
H8A | 0.3328 | 0.8770 | 0.3392 | 0.067* | |
H8B | 0.2723 | 0.8633 | 0.4480 | 0.067* | |
C9 | 0.35711 (8) | 0.76851 (9) | 0.44569 (13) | 0.0558 (4) | |
C10 | 0.45065 (9) | 0.67305 (10) | 0.55103 (16) | 0.0654 (4) | |
H10A | 0.5040 | 0.6820 | 0.5809 | 0.078* | |
H10B | 0.4534 | 0.6424 | 0.4714 | 0.078* | |
C11 | 0.40855 (7) | 0.61462 (8) | 0.64410 (12) | 0.0508 (3) | |
C12 | 0.41917 (10) | 0.52501 (10) | 0.63923 (16) | 0.0682 (4) | |
H12A | 0.4500 | 0.5013 | 0.5762 | 0.082* | |
C13 | 0.38524 (10) | 0.46989 (11) | 0.72545 (16) | 0.0738 (5) | |
H13A | 0.3937 | 0.4098 | 0.7209 | 0.089* | |
C14 | 0.33913 (10) | 0.50362 (12) | 0.81753 (14) | 0.0709 (5) | |
H14A | 0.3168 | 0.4668 | 0.8768 | 0.085* | |
C15 | 0.32603 (11) | 0.59234 (12) | 0.82183 (15) | 0.0785 (5) | |
H15A | 0.2937 | 0.6156 | 0.8832 | 0.094* | |
C16 | 0.36072 (10) | 0.64747 (10) | 0.73521 (14) | 0.0666 (4) | |
H16A | 0.3514 | 0.7075 | 0.7390 | 0.080* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0557 (7) | 0.0377 (7) | 0.0528 (7) | 0.000 | −0.0038 (6) | 0.000 |
O2 | 0.0861 (8) | 0.0440 (6) | 0.0862 (8) | 0.0010 (5) | −0.0371 (6) | −0.0052 (5) |
O3 | 0.0976 (9) | 0.0571 (8) | 0.0913 (8) | −0.0035 (6) | −0.0217 (7) | −0.0175 (6) |
N1 | 0.0536 (6) | 0.0409 (6) | 0.0537 (6) | −0.0004 (5) | −0.0055 (5) | −0.0002 (4) |
N2 | 0.0599 (7) | 0.0475 (7) | 0.0682 (8) | −0.0027 (5) | −0.0049 (6) | 0.0025 (5) |
C1 | 0.0460 (6) | 0.0409 (7) | 0.0461 (7) | −0.0030 (5) | 0.0036 (5) | −0.0002 (5) |
C2 | 0.0466 (7) | 0.0435 (7) | 0.0496 (7) | −0.0019 (5) | 0.0049 (5) | 0.0055 (5) |
C3 | 0.0656 (8) | 0.0450 (8) | 0.0632 (9) | −0.0054 (6) | −0.0017 (7) | 0.0075 (6) |
C4 | 0.0776 (10) | 0.0459 (8) | 0.0794 (11) | 0.0010 (7) | −0.0042 (8) | 0.0185 (7) |
C5 | 0.0630 (9) | 0.0619 (10) | 0.0699 (9) | 0.0028 (7) | −0.0057 (7) | 0.0227 (7) |
C6 | 0.0556 (8) | 0.0609 (9) | 0.0581 (8) | −0.0002 (6) | −0.0055 (6) | 0.0075 (6) |
C7 | 0.0506 (7) | 0.0446 (7) | 0.0536 (7) | −0.0002 (6) | 0.0006 (6) | 0.0047 (5) |
C8 | 0.0567 (7) | 0.0526 (9) | 0.0584 (8) | −0.0057 (6) | −0.0091 (6) | −0.0043 (6) |
C9 | 0.0578 (8) | 0.0503 (8) | 0.0593 (8) | −0.0043 (6) | 0.0004 (6) | −0.0044 (6) |
C10 | 0.0572 (8) | 0.0597 (10) | 0.0794 (10) | 0.0068 (7) | 0.0053 (7) | 0.0083 (7) |
C11 | 0.0485 (7) | 0.0522 (8) | 0.0516 (7) | 0.0032 (6) | −0.0073 (5) | −0.0003 (5) |
C12 | 0.0724 (10) | 0.0589 (9) | 0.0734 (10) | 0.0188 (7) | 0.0086 (8) | 0.0065 (7) |
C13 | 0.0816 (11) | 0.0548 (9) | 0.0850 (12) | 0.0083 (8) | −0.0040 (9) | 0.0156 (8) |
C14 | 0.0796 (10) | 0.0749 (11) | 0.0581 (9) | −0.0146 (9) | −0.0069 (8) | 0.0125 (7) |
C15 | 0.0893 (12) | 0.0861 (13) | 0.0603 (10) | −0.0136 (10) | 0.0152 (9) | −0.0130 (8) |
C16 | 0.0819 (10) | 0.0534 (8) | 0.0644 (9) | −0.0039 (7) | 0.0056 (7) | −0.0143 (7) |
O1—C1 | 1.3627 (14) | C6—C7 | 1.3863 (18) |
O1—C1i | 1.3627 (14) | C6—H6A | 0.9300 |
O2—C7 | 1.3570 (16) | C8—C9 | 1.500 (2) |
O2—C8 | 1.4151 (16) | C8—H8A | 0.9700 |
O3—C9 | 1.2262 (17) | C8—H8B | 0.9700 |
N1—C1 | 1.2979 (16) | C10—C11 | 1.5197 (19) |
N1—N1i | 1.408 (2) | C10—H10A | 0.9700 |
N2—C9 | 1.3352 (19) | C10—H10B | 0.9700 |
N2—C10 | 1.4484 (19) | C11—C16 | 1.3699 (19) |
N2—H2A | 0.8600 | C11—C12 | 1.3805 (19) |
C1—C2 | 1.4630 (16) | C12—C13 | 1.378 (2) |
C2—C3 | 1.389 (2) | C12—H12A | 0.9300 |
C2—C7 | 1.4009 (17) | C13—C14 | 1.365 (2) |
C3—C4 | 1.379 (2) | C13—H13A | 0.9300 |
C3—H3A | 0.9300 | C14—C15 | 1.373 (2) |
C4—C5 | 1.373 (2) | C14—H14A | 0.9300 |
C4—H4A | 0.9300 | C15—C16 | 1.386 (2) |
C5—C6 | 1.382 (2) | C15—H15A | 0.9300 |
C5—H5A | 0.9300 | C16—H16A | 0.9300 |
C1—O1—C1i | 103.62 (13) | O2—C8—H8B | 110.0 |
C7—O2—C8 | 120.64 (11) | C9—C8—H8B | 110.0 |
C1—N1—N1i | 106.43 (7) | H8A—C8—H8B | 108.4 |
C9—N2—C10 | 121.32 (13) | O3—C9—N2 | 124.01 (14) |
C9—N2—H2A | 119.3 | O3—C9—C8 | 119.20 (14) |
C10—N2—H2A | 119.3 | N2—C9—C8 | 116.78 (12) |
N1—C1—O1 | 111.76 (11) | N2—C10—C11 | 115.39 (11) |
N1—C1—C2 | 132.28 (12) | N2—C10—H10A | 108.4 |
O1—C1—C2 | 115.95 (11) | C11—C10—H10A | 108.4 |
C3—C2—C7 | 118.20 (12) | N2—C10—H10B | 108.4 |
C3—C2—C1 | 120.38 (12) | C11—C10—H10B | 108.4 |
C7—C2—C1 | 121.42 (12) | H10A—C10—H10B | 107.5 |
C4—C3—C2 | 121.12 (14) | C16—C11—C12 | 117.94 (13) |
C4—C3—H3A | 119.4 | C16—C11—C10 | 122.48 (13) |
C2—C3—H3A | 119.4 | C12—C11—C10 | 119.57 (12) |
C5—C4—C3 | 119.91 (15) | C13—C12—C11 | 121.56 (14) |
C5—C4—H4A | 120.0 | C13—C12—H12A | 119.2 |
C3—C4—H4A | 120.0 | C11—C12—H12A | 119.2 |
C4—C5—C6 | 120.56 (14) | C14—C13—C12 | 119.91 (16) |
C4—C5—H5A | 119.7 | C14—C13—H13A | 120.0 |
C6—C5—H5A | 119.7 | C12—C13—H13A | 120.0 |
C5—C6—C7 | 119.57 (14) | C13—C14—C15 | 119.41 (14) |
C5—C6—H6A | 120.2 | C13—C14—H14A | 120.3 |
C7—C6—H6A | 120.2 | C15—C14—H14A | 120.3 |
O2—C7—C6 | 123.90 (12) | C14—C15—C16 | 120.36 (15) |
O2—C7—C2 | 115.47 (11) | C14—C15—H15A | 119.8 |
C6—C7—C2 | 120.63 (13) | C16—C15—H15A | 119.8 |
O2—C8—C9 | 108.39 (12) | C11—C16—C15 | 120.77 (15) |
O2—C8—H8A | 110.0 | C11—C16—H16A | 119.6 |
C9—C8—H8A | 110.0 | C15—C16—H16A | 119.6 |
Symmetry code: (i) −x+1, y, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O2 | 0.86 | 2.15 | 2.5523 (16) | 109 |
N2—H2A···N1 | 0.86 | 2.49 | 3.3524 (17) | 177 |
Experimental details
Crystal data | |
Chemical formula | C32H28N4O5 |
Mr | 548.58 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 17.0619 (15), 15.2601 (15), 10.6555 (9) |
β (°) | 90.611 (5) |
V (Å3) | 2774.2 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.53 × 0.40 × 0.30 |
Data collection | |
Diffractometer | Bruker APEXII diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7913, 2880, 2335 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.628 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.158, 1.17 |
No. of reflections | 2880 |
No. of parameters | 187 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.18, −0.13 |
Computer programs: APEX2 (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···O2 | 0.86 | 2.15 | 2.5523 (16) | 109 |
N2—H2A···N1 | 0.86 | 2.49 | 3.3524 (17) | 177 |
Acknowledgements
The authors acknowledge financial support from the National Natural Science Foundation of China (grant No. 20571035) and the Interdisciplinary Innovation Research Fund for Young Scholars, Lanzhou University (grant No. LZU200506).
References
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Heterocyclic 1,3,4-oxadiazole and its derivatives have been studied for a long time because many of these derivatives show biological activity (Patricia et al., 2002) and electron-transporting capability (Wen et al., 2003), in particular as active compounds in organic light emitting diodes (OLEDs) (Kuo et al., 2006). At the same time, these five-membered oxadiazole ring can bind metal ions by N and O donors to expand various novel polymeric frameworks, some with open channels and interesting luminescence properties (Dong et al., 2003). We herein report the synthesis and crystal structure of a new amide-based 1,3,4-oxadiazole bridging ligand, namely the title compound, (I).
As seen from Fig. 1, the molecule of (I) possesses crystallographically imposed C2 symmetry, with the two fold axis bisecting the central 1,3,4-oxadiazole ring. The central two phenyl rings and oxadiazole ring are almost coplanar. The amide groups of molecule appear to form intramolecular hydrogen bonds with both the phenoxy O atom and the oxadiazole N atom (Table 1). In addition, the centroid-to-centroid distance (4.344 Å) of the two terminal benzene rings is so much longer that it is difficult to regard this as representing a significantly π-π stacking interaction.