The asymmetric unit of the title compound, poly[{μ
4-4-[(carboxylatomethyl)sulfanyl]benzoato}(
N,
N-dimethylformamide)zinc], [Zn(C
9H
6O
4S)(C
3H
7NO)]
n, consists of one crystallographically independent Zn
II cation, one 4-[(carboxylatomethyl)sulfanyl]benzoate (
L2−) ligand and one coordinated dimethylformamide (DMF) molecule. The zinc ion is coordinated by five O atoms from four separate
L2− ligands and one DMF molecule, and the ZnO
5 unit displays a distorted square-based-pyramidal geometry. Two ZnO
5 units form a binuclear zinc–tetracarboxylate paddlewheel cluster, and these are bridged by
L2− ligands to generate an intersecting helical chain (Zn
2+ ions as nodes), which is composed of right-handed (
P) and left-handed (
M) helices. Weak C—H
O hydrogen bonds extend the one-dimensional coordinated chain into a weakly bound three-dimensional supramolecular architecture.
Supporting information
CCDC reference: 851732
All reagents and solvents employed were commercially available and used as
received without further purification. A mixture of Zn(NO3)2.6H2O (60 mg, 0.2 mmol), H2L (42 mg, 0.2 mmol) and DMF (10 ml) was sealed in a
25 ml stainless steel reactor with Teflon liner and directly heated to 348 K
for 4 d, and then cooled to room temperature. The crystals were washed with
methanol to give complex (I) in about 45% yield (based on the H2L
ligand).
The hydrogen atoms were positioned geometrically and included in the refinement
using a riding model [C—H = 0.96 Å (CH3), 0.97 Å (CH2), 0.93Å (CH)
and Uiso(H) = 1.2Ueq(parent atom)].
Data collection: SMART (Bruker, 2001); cell refinement: SMART (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009).
poly[{µ
4-4-[(carboxyatomethyl)sulfanyl]benzoato}(
N,
N-
dimethylformamide)zinc]
top
Crystal data top
[Zn(C9H6O4S)(C3H7NO)] | F(000) = 712 |
Mr = 348.66 | Dx = 1.704 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 2096 reflections |
a = 7.873 (3) Å | θ = 2.2–26.8° |
b = 10.225 (3) Å | µ = 1.98 mm−1 |
c = 17.006 (6) Å | T = 298 K |
β = 97.014 (4)° | Block, colourless |
V = 1358.7 (8) Å3 | 0.35 × 0.34 × 0.24 mm |
Z = 4 | |
Data collection top
Bruker SMART APEX II CCD diffractometer | 2402 independent reflections |
Radiation source: fine-focus sealed tube | 1855 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.032 |
ϕ and ω scans | θmax = 25.0°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | h = −9→9 |
Tmin = 0.544, Tmax = 0.648 | k = −9→12 |
5851 measured reflections | l = −20→15 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.037 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.091 | H-atom parameters constrained |
S = 1.00 | w = 1/[σ2(Fo2) + (0.0468P)2 + 0.359P] where P = (Fo2 + 2Fc2)/3 |
2402 reflections | (Δ/σ)max = 0.001 |
183 parameters | Δρmax = 0.65 e Å−3 |
0 restraints | Δρmin = −0.50 e Å−3 |
Crystal data top
[Zn(C9H6O4S)(C3H7NO)] | V = 1358.7 (8) Å3 |
Mr = 348.66 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 7.873 (3) Å | µ = 1.98 mm−1 |
b = 10.225 (3) Å | T = 298 K |
c = 17.006 (6) Å | 0.35 × 0.34 × 0.24 mm |
β = 97.014 (4)° | |
Data collection top
Bruker SMART APEX II CCD diffractometer | 2402 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 1855 reflections with I > 2σ(I) |
Tmin = 0.544, Tmax = 0.648 | Rint = 0.032 |
5851 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.091 | H-atom parameters constrained |
S = 1.00 | Δρmax = 0.65 e Å−3 |
2402 reflections | Δρmin = −0.50 e Å−3 |
183 parameters | |
Special details top
Experimental. 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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Zn1 | 0.44726 (5) | 0.98040 (4) | 0.07850 (2) | 0.02767 (15) | |
N1 | 0.3960 (4) | 0.7560 (3) | 0.27221 (18) | 0.0398 (8) | |
O1 | 0.3840 (4) | 0.8147 (2) | 0.01288 (16) | 0.0459 (7) | |
O2 | 0.4537 (3) | 0.8424 (2) | −0.10938 (16) | 0.0428 (7) | |
O3 | 0.2300 (3) | 1.0709 (3) | 0.02693 (15) | 0.0388 (6) | |
O4 | 0.3076 (3) | 1.0928 (3) | −0.09457 (15) | 0.0415 (7) | |
O5 | 0.3739 (3) | 0.9127 (3) | 0.17854 (14) | 0.0350 (6) | |
S1 | 0.02332 (13) | 1.27397 (10) | −0.15567 (6) | 0.0387 (3) | |
C1 | 0.3909 (5) | 0.7776 (4) | −0.0567 (2) | 0.0347 (9) | |
C2 | 0.3150 (5) | 0.6466 (3) | −0.0796 (2) | 0.0320 (9) | |
C3 | 0.2695 (6) | 0.5616 (4) | −0.0231 (2) | 0.0465 (11) | |
H3 | 0.2935 | 0.5838 | 0.0302 | 0.056* | |
C4 | 0.1891 (6) | 0.4441 (4) | −0.0433 (2) | 0.0451 (11) | |
H4 | 0.1617 | 0.3875 | −0.0039 | 0.054* | |
C5 | 0.1495 (4) | 0.4109 (3) | −0.1225 (2) | 0.0302 (8) | |
C6 | 0.2003 (5) | 0.4932 (4) | −0.1797 (2) | 0.0349 (9) | |
H6 | 0.1786 | 0.4700 | −0.2329 | 0.042* | |
C7 | 0.2829 (5) | 0.6092 (4) | −0.1588 (2) | 0.0338 (9) | |
H7 | 0.3176 | 0.6631 | −0.1979 | 0.041* | |
C8 | 0.2065 (5) | 1.1074 (3) | −0.0442 (2) | 0.0308 (8) | |
C9 | 0.0339 (4) | 1.1706 (4) | −0.0700 (2) | 0.0328 (9) | |
H9A | 0.0021 | 1.2220 | −0.0261 | 0.039* | |
H9B | −0.0507 | 1.1018 | −0.0805 | 0.039* | |
C10 | 0.4246 (5) | 0.8026 (4) | 0.2037 (2) | 0.0368 (9) | |
H10 | 0.4860 | 0.7514 | 0.1718 | 0.044* | |
C11 | 0.3021 (6) | 0.8301 (5) | 0.3251 (3) | 0.0617 (14) | |
H11A | 0.2773 | 0.9156 | 0.3033 | 0.092* | |
H11B | 0.3697 | 0.8380 | 0.3758 | 0.092* | |
H11C | 0.1970 | 0.7859 | 0.3312 | 0.092* | |
C12 | 0.4597 (7) | 0.6270 (5) | 0.2993 (3) | 0.0736 (16) | |
H12A | 0.5175 | 0.5870 | 0.2590 | 0.110* | |
H12B | 0.3653 | 0.5730 | 0.3098 | 0.110* | |
H12C | 0.5379 | 0.6366 | 0.3469 | 0.110* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Zn1 | 0.0316 (3) | 0.0281 (3) | 0.0245 (2) | −0.00339 (18) | 0.00857 (18) | 0.00144 (18) |
N1 | 0.0414 (19) | 0.045 (2) | 0.0337 (18) | −0.0073 (16) | 0.0081 (16) | 0.0103 (16) |
O1 | 0.0620 (19) | 0.0329 (16) | 0.0432 (17) | −0.0125 (14) | 0.0084 (15) | −0.0106 (13) |
O2 | 0.0482 (17) | 0.0312 (16) | 0.0502 (17) | −0.0127 (13) | 0.0107 (15) | −0.0025 (13) |
O3 | 0.0353 (15) | 0.0439 (17) | 0.0371 (16) | −0.0003 (12) | 0.0041 (12) | 0.0087 (12) |
O4 | 0.0338 (15) | 0.0519 (18) | 0.0401 (16) | 0.0082 (13) | 0.0098 (13) | 0.0055 (13) |
O5 | 0.0415 (15) | 0.0377 (17) | 0.0277 (14) | 0.0003 (13) | 0.0121 (12) | 0.0075 (12) |
S1 | 0.0440 (6) | 0.0309 (6) | 0.0381 (6) | −0.0064 (5) | −0.0077 (5) | 0.0012 (4) |
C1 | 0.027 (2) | 0.030 (2) | 0.047 (2) | 0.0013 (17) | 0.0045 (18) | −0.0051 (19) |
C2 | 0.031 (2) | 0.026 (2) | 0.039 (2) | −0.0027 (16) | 0.0076 (18) | 0.0004 (16) |
C3 | 0.069 (3) | 0.043 (3) | 0.027 (2) | −0.015 (2) | 0.003 (2) | −0.0047 (18) |
C4 | 0.071 (3) | 0.034 (2) | 0.031 (2) | −0.019 (2) | 0.007 (2) | 0.0035 (18) |
C5 | 0.033 (2) | 0.024 (2) | 0.033 (2) | −0.0001 (16) | 0.0017 (17) | 0.0005 (16) |
C6 | 0.038 (2) | 0.037 (2) | 0.029 (2) | 0.0021 (18) | 0.0016 (17) | 0.0010 (17) |
C7 | 0.040 (2) | 0.029 (2) | 0.034 (2) | −0.0042 (18) | 0.0095 (18) | 0.0027 (17) |
C8 | 0.035 (2) | 0.019 (2) | 0.039 (2) | −0.0080 (16) | 0.0056 (19) | −0.0027 (17) |
C9 | 0.031 (2) | 0.026 (2) | 0.041 (2) | −0.0037 (16) | 0.0038 (18) | 0.0007 (17) |
C10 | 0.036 (2) | 0.042 (3) | 0.035 (2) | −0.0087 (19) | 0.0097 (18) | 0.0001 (19) |
C11 | 0.075 (3) | 0.077 (4) | 0.037 (2) | −0.012 (3) | 0.021 (3) | 0.008 (2) |
C12 | 0.084 (4) | 0.065 (4) | 0.074 (4) | −0.002 (3) | 0.017 (3) | 0.036 (3) |
Geometric parameters (Å, º) top
Zn1—O1 | 2.056 (3) | C3—C4 | 1.382 (5) |
Zn1—O2i | 2.017 (3) | C3—H3 | 0.9300 |
Zn1—O3 | 2.045 (3) | C4—C5 | 1.388 (5) |
Zn1—O4i | 2.057 (3) | C4—H4 | 0.9300 |
Zn1—O5 | 1.987 (2) | C5—C6 | 1.382 (5) |
Zn1—Zn1i | 2.9188 (11) | C6—C7 | 1.379 (5) |
N1—C10 | 1.304 (5) | C6—H6 | 0.9300 |
N1—C11 | 1.446 (5) | C7—H7 | 0.9300 |
N1—C12 | 1.465 (6) | C8—C9 | 1.520 (5) |
O1—C1 | 1.250 (4) | C9—H9A | 0.9700 |
O2—C1 | 1.263 (4) | C9—H9B | 0.9700 |
O3—C8 | 1.258 (4) | C10—H10 | 0.9300 |
O4—C8 | 1.247 (4) | C11—H11A | 0.9600 |
O5—C10 | 1.252 (4) | C11—H11B | 0.9600 |
C1—C2 | 1.498 (5) | C11—H11C | 0.9600 |
S1—C9 | 1.794 (4) | C12—H12A | 0.9600 |
C5—S1ii | 1.769 (4) | C12—H12B | 0.9600 |
C2—C3 | 1.375 (5) | C12—H12C | 0.9600 |
C2—C7 | 1.393 (5) | | |
| | | |
O5—Zn1—O2i | 103.50 (11) | C5—C4—H4 | 120.2 |
O5—Zn1—O3 | 102.08 (10) | C6—C5—C4 | 119.0 (3) |
O2i—Zn1—O3 | 88.95 (11) | C6—C5—S1ii | 117.2 (3) |
O5—Zn1—O1 | 95.82 (11) | C4—C5—S1ii | 123.6 (3) |
O2i—Zn1—O1 | 160.39 (11) | C7—C6—C5 | 120.6 (4) |
O3—Zn1—O1 | 90.32 (11) | C7—C6—H6 | 119.7 |
O5—Zn1—O4i | 97.23 (10) | C5—C6—H6 | 119.7 |
O2i—Zn1—O4i | 88.02 (11) | C6—C7—C2 | 120.7 (3) |
O3—Zn1—O4i | 160.63 (10) | C6—C7—H7 | 119.7 |
O1—Zn1—O4i | 86.19 (12) | C2—C7—H7 | 119.7 |
O5—Zn1—Zn1i | 167.45 (8) | O4—C8—O3 | 126.4 (4) |
O2i—Zn1—Zn1i | 88.32 (8) | O4—C8—C9 | 118.4 (3) |
O3—Zn1—Zn1i | 82.07 (8) | O3—C8—C9 | 115.2 (3) |
O1—Zn1—Zn1i | 72.18 (8) | C8—C9—S1 | 115.8 (3) |
O4i—Zn1—Zn1i | 78.72 (7) | C8—C9—H9A | 108.3 |
C10—N1—C11 | 121.4 (4) | S1—C9—H9A | 108.3 |
C10—N1—C12 | 121.4 (4) | C8—C9—H9B | 108.3 |
C11—N1—C12 | 117.2 (4) | S1—C9—H9B | 108.3 |
C1—O1—Zn1 | 136.7 (3) | H9A—C9—H9B | 107.4 |
C1—O2—Zn1i | 117.4 (2) | O5—C10—N1 | 123.5 (4) |
C8—O3—Zn1 | 124.3 (2) | O5—C10—H10 | 118.3 |
C8—O4—Zn1i | 128.3 (2) | N1—C10—H10 | 118.3 |
C10—O5—Zn1 | 119.4 (2) | N1—C11—H11A | 109.5 |
C5iii—S1—C9 | 103.83 (17) | N1—C11—H11B | 109.5 |
O1—C1—O2 | 125.3 (4) | H11A—C11—H11B | 109.5 |
O1—C1—C2 | 117.1 (3) | N1—C11—H11C | 109.5 |
O2—C1—C2 | 117.6 (3) | H11A—C11—H11C | 109.5 |
C3—C2—C7 | 118.0 (3) | H11B—C11—H11C | 109.5 |
C3—C2—C1 | 120.9 (4) | N1—C12—H12A | 109.5 |
C7—C2—C1 | 121.1 (3) | N1—C12—H12B | 109.5 |
C2—C3—C4 | 121.8 (4) | H12A—C12—H12B | 109.5 |
C2—C3—H3 | 119.1 | N1—C12—H12C | 109.5 |
C4—C3—H3 | 119.1 | H12A—C12—H12C | 109.5 |
C3—C4—C5 | 119.7 (4) | H12B—C12—H12C | 109.5 |
C3—C4—H4 | 120.2 | | |
| | | |
O5—Zn1—O1—C1 | −179.8 (4) | O2—C1—C2—C7 | −12.8 (5) |
O2i—Zn1—O1—C1 | −9.7 (6) | C7—C2—C3—C4 | −2.1 (6) |
O3—Zn1—O1—C1 | 78.1 (4) | C1—C2—C3—C4 | 175.7 (4) |
O4i—Zn1—O1—C1 | −82.9 (4) | C2—C3—C4—C5 | −1.3 (7) |
Zn1i—Zn1—O1—C1 | −3.5 (4) | C3—C4—C5—C6 | 3.7 (6) |
O5—Zn1—O3—C8 | −166.3 (3) | C3—C4—C5—S1ii | −171.7 (3) |
O2i—Zn1—O3—C8 | 90.1 (3) | C4—C5—C6—C7 | −2.7 (6) |
O1—Zn1—O3—C8 | −70.3 (3) | S1ii—C5—C6—C7 | 173.0 (3) |
O4i—Zn1—O3—C8 | 9.1 (5) | C5—C6—C7—C2 | −0.7 (6) |
Zn1i—Zn1—O3—C8 | 1.6 (3) | C3—C2—C7—C6 | 3.1 (6) |
O2i—Zn1—O5—C10 | −126.8 (3) | C1—C2—C7—C6 | −174.7 (3) |
O3—Zn1—O5—C10 | 141.4 (3) | Zn1i—O4—C8—O3 | −5.6 (5) |
O1—Zn1—O5—C10 | 49.8 (3) | Zn1i—O4—C8—C9 | 176.9 (2) |
O4i—Zn1—O5—C10 | −37.1 (3) | Zn1—O3—C8—O4 | 1.4 (5) |
Zn1i—Zn1—O5—C10 | 33.2 (5) | Zn1—O3—C8—C9 | 179.1 (2) |
Zn1—O1—C1—O2 | 3.1 (6) | O4—C8—C9—S1 | −23.8 (4) |
Zn1—O1—C1—C2 | −175.6 (3) | O3—C8—C9—S1 | 158.4 (3) |
Zn1i—O2—C1—O1 | 0.6 (5) | C5iii—S1—C9—C8 | −69.4 (3) |
Zn1i—O2—C1—C2 | 179.2 (2) | Zn1—O5—C10—N1 | 173.4 (3) |
O1—C1—C2—C3 | −11.8 (5) | C11—N1—C10—O5 | −0.2 (6) |
O2—C1—C2—C3 | 169.4 (4) | C12—N1—C10—O5 | −179.4 (4) |
O1—C1—C2—C7 | 165.9 (3) | | |
Symmetry codes: (i) −x+1, −y+2, −z; (ii) x, y−1, z; (iii) x, y+1, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9B···O3iv | 0.97 | 2.50 | 3.365 (4) | 148 |
C12—H12B···O5v | 0.96 | 2.52 | 3.476 (6) | 172 |
Symmetry codes: (iv) −x, −y+2, −z; (v) −x+1/2, y−1/2, −z+1/2. |
Experimental details
Crystal data |
Chemical formula | [Zn(C9H6O4S)(C3H7NO)] |
Mr | 348.66 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 298 |
a, b, c (Å) | 7.873 (3), 10.225 (3), 17.006 (6) |
β (°) | 97.014 (4) |
V (Å3) | 1358.7 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.98 |
Crystal size (mm) | 0.35 × 0.34 × 0.24 |
|
Data collection |
Diffractometer | Bruker SMART APEX II CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.544, 0.648 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5851, 2402, 1855 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.091, 1.00 |
No. of reflections | 2402 |
No. of parameters | 183 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.65, −0.50 |
Selected bond lengths (Å) topZn1—O1 | 2.056 (3) | Zn1—O5 | 1.987 (2) |
Zn1—O2i | 2.017 (3) | S1—C9 | 1.794 (4) |
Zn1—O3 | 2.045 (3) | C5—S1ii | 1.769 (4) |
Zn1—O4i | 2.057 (3) | | |
Symmetry codes: (i) −x+1, −y+2, −z; (ii) x, y−1, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9B···O3iii | 0.97 | 2.50 | 3.365 (4) | 148 |
C12—H12B···O5iv | 0.96 | 2.52 | 3.476 (6) | 172 |
Symmetry codes: (iii) −x, −y+2, −z; (iv) −x+1/2, y−1/2, −z+1/2. |
The design and synthesis of metal–organic coordination polymers have attracted great interest in recent years, not only for their structural diversity and intriguing molecular topologies, but also for their potential as a new class of solid-state materials applied in the fields of separation, catalysis, gas storage and drug delivery (Kitagawa & Uemura, 2005; Dincă & Long, 2008; Choi & Suh, 2004). To construct such materials, judicious selection of bridging ligands is one of the various factors to be taken into account. Flexible ligands have been extensively explored in coordination chemistry and crystal engineering because of their numerous conformations and coordination modes observed in the coordination process (Ma et al., 2008; Zhang et al., 2008). In this contribution, we choose a new flexible ligand, 4-[(carboxylatomethyl)sulfanyl]benzoate (L2-), as a bridging ligand to synthesize the coordination polymers. Herein we report a new binuclear ZnII polymer with paddlewheel building units and intersecting helical chains (Zn2+ ions as nodes), which is composed of P- (right-) and M-(left-)handed helices.
In the structure of (I) (Fig. 1, Table 1), the Zn2+ centre adopts a five-coordinated mode with a distorted square-based-pyramidal geometry (ZnO5) via binding to one axial dimethylformamide (DMF) oxygen atom and four oxygen atoms from four different CO2- groups of L2- ligands in the basal plane. The four carboxylate O atoms [O1, O2i, O3, O4i; symmetry code: (i) -x + 1, -y + 2, -z] are coplanar with an r.m.s. deviation of 0.0139 (14) Å . Each L2- ligand bridges four different Zn2+ ions, via bridging carboxylate groups at each end of the ligand molecule, to form a one-dimensional coordination polymer. The two Zn2+ centres are bridged by four carboxylate groups from different L2- ligands in a syn–syn bidentate mode, forming a paddlewheel secondary building unit (SBU). The intradimer Zn···Zn separation is 2.9186 (11) Å, within the nomal range found in other reported structures with the same paddlewheel core [Zn2O2(O2CR)4] (Zhou et al., 2000; Kwak et al., 2009). A dramatic, almost perpendicular, twist between the two carboxylate groups in the L2- ligand is observed, with a dihedral angle of 87.1 (4)° (Fig. 1).
In (I), each paddlewheel unit connects to two neighbouring paddlewheel clusters via bridging L2- anions, which adopt a bridging tetradentate mode. It should be emphasized that because of the orientation of the carboxylate coordination sites and flexibility of the L2- ligand, the quadrate rings in the one-dimensional chain are highly distorted. Interestingly, these quadrate rings are interlinked by sharing the Zn2+ ions to form an intersecting helical chain, in which P- and M-handed helices can be distinguished (Fig. 2). Obviously, the twist of the L2- ligand is responsible for the formation of the helical chain.
To date, only a few stuctures with the same paddlewheel core [Zn4O2(O2CR)4] [Zn2?] have been reported. These are the zero-dimensional Lantern-type [Zn2(O2CCF3)6]2- ions (Demirhan et al., 2002); the zero-dimensional dinuclear [Zn2(Indo)4(DMA)2].2DMA [IndoH = 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid and DMA = N,N-dimethylacetamide; Zhou et al., 2000]; the zero-dimensional overall 'figure-of-eight' shape [Zn2(C18H12N2O4S3)2(C3H7NO)2] (Wang et al., 2009); the two-dimensional square-grid motif {[Zn2(C8H4O2)2(H2O)2].2C4H9NO}n (Lv & Ng, 2007); the one-dimensional zigzag chain [Zn2(O2CPh)4(H2O)2][Zn(O2CPh)2(bpe)]n, (II) [bpe = 1,2-bis(4-pyridyl)ethane; Kwak et al., 2009]; the two-dimensional layer structure [Zn2(C8H4O4)2(C2H6OS)2].5C2H6OS (Yang et al., 2005); the three-dimensional (3,24)-connected metal–organic framework [Zn24(L)8(H2O)24]n {L = 5,5',5''-[benzene-1,3,5-triyltris(carbonylimino)]tris-1,3-benzenedicarboxylic acid; Zou et al., 2008}; the three-dimensional twofold interpenetrating polyhedral metal–organic framework {[Zn3(BTPCA)2(H2O)3].py.3DMSO}n with a primitive cubic network [BTPCA = 1,1',1''-(benzene-1,3,5-triyl)tripiperidine-4-carboxylic acid, py = ?, DMSO = dimethyl sulfoxide?; Zhao et al., 2009]. The chain structure of complex (I) is quite different from that of complex (II), which consists of mononuclear Zn(O2CC6H5)2 units bridged by a bpe ligand to form a one-dimensional zigzag chain. Importantly, such an example of the coexistence of a binuclear ZnII-tetracarboxylate paddlewheel cluster and intersecting P- and M-handed helical chains is unique, to the best of our knowledge.
Another interesting feature of complex (I) is the non-covalent interactions (Table 2). In the landmark study by Desiraju (1996), C—H···O contacts occur within certain distance (2.30 < d < 2.84 Å, 3.18 < D < 3.60 Å) and angle (122< θ < 160°) ranges. There are weak C—H···O hydrogen bonds between two L2- ligands [C9···O3iv; symmetry code: (iv) -x, -y + 2, -z] as well as between two DMF molecules [C12···O5v; symmetry code: (v) -x + 1/2, y-1/2, -z+1/2] which link the one-dimensional helical chains to generate a weakly bound three-dimensional supramolecular architecture as depicted in Fig. 3.