In the title coordination polymer, [Cu(C11H7O2)(OH)(H2O)]n, the CuII center is five-coordinated by two O atoms from two different naphthalene-1-carboxylate (L) ligands, one O atom from one coordinated water molecule and two O atoms from two hydroxide anions. L ligands and hydroxide anions jointly bridge adjacent CuII centers to generate a one-dimensional chain along the b-axis direction. The results reveal that the steric bulk of the naphthalene ring system in L may play an important role in the formation of the title complex.
Supporting information
CCDC reference: 672408
A solution of HL (0.05 mmol) in CH3OH (10 ml) in the presence of excess
2,6-dimethylpyridine (ca 0.05 ml for adjusting the pH value of reaction
system to basic condition) was carefully layered on top of an aqueous solution
(15 ml) of Cu(NO3)2 (0.1 mmol) in a test tube. Blue single crystals
suitable for X-ray analysis appeared at the boundary between CH3OH and H2O
after ca one month at room temperature (yield ~30% based on
HL). Analysis calculated for C11H10CuO4: C 48.98, H 3.74%; found:
C 49.09, H 3.67%.
H atoms of the water molecules and hydroxy anions were located in difference
maps and were allowed to ride on the parent atoms for refinement [with
Uiso(H) = 1.2Ueq(O)]. The remaining H atoms were included in
calculated positions and treated in the subsequent refinement as riding atoms
[C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C)].
Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL (Bruker, 1998) and PLATON (Spek, 2003).
catena-Poly[[aquacopper(II)]-µ-hydroxido-µ-naphthalene-1-carboxylato-
κ2O:
O']
top
Crystal data top
[Cu(C11H7O2)(OH)(H2O)] | F(000) = 548 |
Mr = 269.73 | Dx = 1.732 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 2348 reflections |
a = 15.9395 (7) Å | θ = 3.5–25.3° |
b = 6.2397 (2) Å | µ = 2.11 mm−1 |
c = 10.6094 (6) Å | T = 294 K |
β = 101.383 (3)° | Block, blue |
V = 1034.43 (8) Å3 | 0.16 × 0.14 × 0.12 mm |
Z = 4 | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 2545 independent reflections |
Radiation source: fine-focus sealed tube | 2010 reflections with i > 2σ(I) |
Graphite monochromator | Rint = 0.042 |
phi and ω scans | θmax = 28.3°, θmin = 2.6° |
Absorption correction: multi-scan (SADABS; Bruker,1998) | h = −21→20 |
Tmin = 0.729, Tmax = 0.786 | k = −8→8 |
10552 measured reflections | l = −11→14 |
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)] = 0.036 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.084 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0378P)2 + 0.4928P] where P = (Fo2 + 2Fc2)/3 |
2545 reflections | (Δ/σ)max = 0.001 |
145 parameters | Δρmax = 0.43 e Å−3 |
0 restraints | Δρmin = −0.42 e Å−3 |
Crystal data top
[Cu(C11H7O2)(OH)(H2O)] | V = 1034.43 (8) Å3 |
Mr = 269.73 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 15.9395 (7) Å | µ = 2.11 mm−1 |
b = 6.2397 (2) Å | T = 294 K |
c = 10.6094 (6) Å | 0.16 × 0.14 × 0.12 mm |
β = 101.383 (3)° | |
Data collection top
Bruker SMART CCD area-detector diffractometer | 2545 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker,1998) | 2010 reflections with i > 2σ(I) |
Tmin = 0.729, Tmax = 0.786 | Rint = 0.042 |
10552 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.084 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.43 e Å−3 |
2545 reflections | Δρmin = −0.42 e Å−3 |
145 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cu1 | 0.503028 (18) | 0.55314 (4) | 0.74841 (3) | 0.02082 (11) | |
C1 | 0.34611 (16) | 0.3047 (4) | 0.6379 (2) | 0.0237 (5) | |
C2 | 0.25356 (16) | 0.3156 (4) | 0.5722 (2) | 0.0245 (5) | |
C3 | 0.20007 (17) | 0.1589 (4) | 0.6014 (3) | 0.0339 (6) | |
H3 | 0.2225 | 0.0489 | 0.6572 | 0.041* | |
C4 | 0.11182 (19) | 0.1620 (5) | 0.5485 (3) | 0.0410 (7) | |
H4 | 0.0763 | 0.0566 | 0.5711 | 0.049* | |
C5 | 0.07856 (18) | 0.3184 (5) | 0.4646 (3) | 0.0382 (7) | |
H5 | 0.0203 | 0.3185 | 0.4297 | 0.046* | |
C6 | 0.13114 (17) | 0.4815 (4) | 0.4294 (3) | 0.0300 (6) | |
C7 | 0.22005 (16) | 0.4844 (4) | 0.4841 (3) | 0.0258 (5) | |
C8 | 0.0962 (2) | 0.6442 (5) | 0.3396 (3) | 0.0402 (7) | |
H8 | 0.0380 | 0.6438 | 0.3044 | 0.048* | |
C9 | 0.1467 (2) | 0.7995 (5) | 0.3048 (3) | 0.0456 (8) | |
H9 | 0.1232 | 0.9032 | 0.2453 | 0.055* | |
C10 | 0.2344 (2) | 0.8031 (5) | 0.3590 (3) | 0.0438 (8) | |
H10 | 0.2686 | 0.9106 | 0.3352 | 0.053* | |
C11 | 0.27066 (18) | 0.6512 (5) | 0.4463 (3) | 0.0343 (6) | |
H11 | 0.3289 | 0.6572 | 0.4811 | 0.041* | |
O1 | 0.37940 (11) | 0.1210 (3) | 0.65603 (19) | 0.0311 (4) | |
O2 | 0.38330 (11) | 0.4794 (3) | 0.6721 (2) | 0.0317 (4) | |
O3 | 0.54490 (11) | 0.2984 (2) | 0.67951 (17) | 0.0224 (4) | |
H31 | 0.5987 | 0.2960 | 0.7074 | 0.027* | |
O4 | 0.52295 (14) | 0.7749 (3) | 0.57325 (19) | 0.0376 (5) | |
H41 | 0.4995 | 0.7371 | 0.4975 | 0.045* | |
H42 | 0.5714 | 0.8205 | 0.5631 | 0.045* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cu1 | 0.01926 (17) | 0.01780 (17) | 0.02369 (18) | −0.00016 (11) | 0.00010 (11) | −0.00240 (12) |
C1 | 0.0211 (13) | 0.0285 (13) | 0.0214 (13) | 0.0004 (10) | 0.0041 (10) | −0.0020 (10) |
C2 | 0.0195 (12) | 0.0277 (13) | 0.0251 (13) | 0.0001 (10) | 0.0018 (10) | −0.0029 (10) |
C3 | 0.0272 (15) | 0.0303 (14) | 0.0404 (17) | −0.0003 (11) | −0.0023 (12) | 0.0066 (12) |
C4 | 0.0260 (15) | 0.0414 (17) | 0.054 (2) | −0.0088 (13) | 0.0044 (14) | 0.0036 (14) |
C5 | 0.0176 (13) | 0.0500 (18) | 0.0432 (18) | −0.0030 (12) | −0.0034 (12) | −0.0019 (14) |
C6 | 0.0237 (13) | 0.0380 (15) | 0.0266 (14) | 0.0046 (11) | 0.0008 (11) | −0.0026 (11) |
C7 | 0.0226 (13) | 0.0300 (13) | 0.0238 (14) | 0.0039 (10) | 0.0023 (10) | −0.0004 (10) |
C8 | 0.0290 (15) | 0.0521 (18) | 0.0353 (17) | 0.0091 (14) | −0.0035 (13) | 0.0011 (14) |
C9 | 0.048 (2) | 0.0486 (19) | 0.0379 (18) | 0.0151 (15) | 0.0026 (15) | 0.0140 (15) |
C10 | 0.0461 (19) | 0.0450 (18) | 0.0414 (18) | 0.0001 (14) | 0.0109 (15) | 0.0127 (14) |
C11 | 0.0252 (14) | 0.0413 (16) | 0.0358 (16) | −0.0006 (12) | 0.0046 (12) | 0.0071 (13) |
O1 | 0.0226 (9) | 0.0238 (9) | 0.0425 (12) | 0.0002 (7) | −0.0046 (8) | 0.0015 (8) |
O2 | 0.0217 (9) | 0.0239 (9) | 0.0442 (12) | 0.0009 (7) | −0.0064 (8) | −0.0057 (8) |
O3 | 0.0212 (9) | 0.0208 (8) | 0.0251 (9) | 0.0008 (7) | 0.0041 (7) | 0.0013 (7) |
O4 | 0.0474 (13) | 0.0439 (11) | 0.0214 (10) | −0.0047 (10) | 0.0066 (9) | 0.0015 (9) |
Geometric parameters (Å, º) top
Cu1—O3 | 1.9232 (16) | C6—C7 | 1.422 (4) |
Cu1—O3i | 1.9342 (16) | C6—C8 | 1.428 (4) |
Cu1—O2 | 1.9747 (18) | C7—C11 | 1.422 (4) |
Cu1—O1i | 1.9923 (18) | C8—C9 | 1.356 (4) |
Cu1—O4 | 2.3879 (19) | C8—H8 | 0.9300 |
C1—O2 | 1.260 (3) | C9—C10 | 1.403 (5) |
C1—O1 | 1.262 (3) | C9—H9 | 0.9300 |
C1—C2 | 1.504 (3) | C10—C11 | 1.370 (4) |
C2—C3 | 1.372 (4) | C10—H10 | 0.9300 |
C2—C7 | 1.439 (4) | C11—H11 | 0.9300 |
C3—C4 | 1.408 (4) | O1—Cu1ii | 1.9923 (18) |
C3—H3 | 0.9300 | O4—H41 | 0.8500 |
C4—C5 | 1.356 (4) | O4—H42 | 0.8500 |
C4—H4 | 0.9300 | O3—Cu1ii | 1.9342 (16) |
C5—C6 | 1.414 (4) | O3—H31 | 0.8500 |
C5—H5 | 0.9300 | | |
| | | |
O3—Cu1—O3i | 176.35 (5) | C5—C6—C8 | 121.0 (3) |
O3—Cu1—O2 | 91.80 (8) | C7—C6—C8 | 119.3 (3) |
O3i—Cu1—O2 | 85.48 (7) | C6—C7—C11 | 118.0 (2) |
O3—Cu1—O1i | 90.40 (8) | C6—C7—C2 | 117.9 (2) |
O3i—Cu1—O1i | 92.06 (8) | C11—C7—C2 | 124.1 (2) |
O2—Cu1—O1i | 173.75 (8) | C9—C8—C6 | 121.0 (3) |
O3—Cu1—O4 | 94.23 (7) | C9—C8—H8 | 119.5 |
O3i—Cu1—O4 | 88.44 (7) | C6—C8—H8 | 119.5 |
O2—Cu1—O4 | 94.71 (8) | C8—C9—C10 | 119.8 (3) |
O1i—Cu1—O4 | 90.95 (8) | C8—C9—H9 | 120.1 |
O2—C1—O1 | 125.6 (2) | C10—C9—H9 | 120.1 |
O2—C1—C2 | 117.2 (2) | C11—C10—C9 | 121.2 (3) |
O1—C1—C2 | 117.1 (2) | C11—C10—H10 | 119.4 |
C3—C2—C7 | 120.1 (2) | C9—C10—H10 | 119.4 |
C3—C2—C1 | 117.4 (2) | C10—C11—C7 | 120.7 (3) |
C7—C2—C1 | 122.6 (2) | C10—C11—H11 | 119.7 |
C2—C3—C4 | 121.1 (3) | C7—C11—H11 | 119.7 |
C2—C3—H3 | 119.5 | C1—O1—Cu1ii | 126.57 (17) |
C4—C3—H3 | 119.5 | Cu1—O4—H41 | 118.2 |
C5—C4—C3 | 120.1 (3) | Cu1—O4—H42 | 123.8 |
C5—C4—H4 | 119.9 | H41—O4—H42 | 102.5 |
C3—C4—H4 | 119.9 | C1—O2—Cu1 | 132.96 (17) |
C4—C5—C6 | 121.0 (3) | Cu1—O3—Cu1ii | 108.05 (8) |
C4—C5—H5 | 119.5 | Cu1—O3—H31 | 106.5 |
C6—C5—H5 | 119.5 | Cu1ii—O3—H31 | 107.4 |
C5—C6—C7 | 119.8 (3) | | |
| | | |
O2—C1—C2—C3 | −141.6 (3) | C5—C6—C8—C9 | −179.4 (3) |
O1—C1—C2—C3 | 37.2 (4) | C7—C6—C8—C9 | 0.7 (4) |
O2—C1—C2—C7 | 36.8 (4) | C6—C8—C9—C10 | −1.0 (5) |
O1—C1—C2—C7 | −144.4 (3) | C8—C9—C10—C11 | 0.5 (5) |
C7—C2—C3—C4 | −1.2 (4) | C9—C10—C11—C7 | 0.2 (5) |
C1—C2—C3—C4 | 177.3 (3) | C6—C7—C11—C10 | −0.4 (4) |
C2—C3—C4—C5 | 1.6 (5) | C2—C7—C11—C10 | 178.1 (3) |
C3—C4—C5—C6 | −0.5 (5) | O2—C1—O1—Cu1ii | 3.7 (4) |
C4—C5—C6—C7 | −1.1 (4) | C2—C1—O1—Cu1ii | −174.98 (16) |
C4—C5—C6—C8 | 179.0 (3) | O1—C1—O2—Cu1 | 6.4 (4) |
C5—C6—C7—C11 | −179.9 (3) | C2—C1—O2—Cu1 | −174.93 (17) |
C8—C6—C7—C11 | −0.1 (4) | O3—Cu1—O2—C1 | 24.1 (3) |
C5—C6—C7—C2 | 1.4 (4) | O3i—Cu1—O2—C1 | −153.4 (3) |
C8—C6—C7—C2 | −178.7 (2) | O4—Cu1—O2—C1 | 118.5 (3) |
C3—C2—C7—C6 | −0.3 (4) | O2—Cu1—O3—Cu1ii | −61.24 (9) |
C1—C2—C7—C6 | −178.7 (2) | O1i—Cu1—O3—Cu1ii | 112.91 (9) |
C3—C2—C7—C11 | −178.8 (3) | O4—Cu1—O3—Cu1ii | −156.11 (9) |
C1—C2—C7—C11 | 2.8 (4) | | |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x+1, y−1/2, −z+3/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H41···O3iii | 0.85 | 1.88 | 2.725 (3) | 169 |
O3—H31···O1i | 0.85 | 2.48 | 2.779 (2) | 102 |
O3—H31···O2ii | 0.85 | 2.34 | 2.653 (2) | 102 |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x+1, y−1/2, −z+3/2; (iii) −x+1, −y+1, −z+1. |
Experimental details
Crystal data |
Chemical formula | [Cu(C11H7O2)(OH)(H2O)] |
Mr | 269.73 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 294 |
a, b, c (Å) | 15.9395 (7), 6.2397 (2), 10.6094 (6) |
β (°) | 101.383 (3) |
V (Å3) | 1034.43 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.11 |
Crystal size (mm) | 0.16 × 0.14 × 0.12 |
|
Data collection |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker,1998) |
Tmin, Tmax | 0.729, 0.786 |
No. of measured, independent and observed [i > 2σ(I)] reflections | 10552, 2545, 2010 |
Rint | 0.042 |
(sin θ/λ)max (Å−1) | 0.667 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.084, 1.03 |
No. of reflections | 2545 |
No. of parameters | 145 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.43, −0.42 |
Selected geometric parameters (Å, º) topCu1—O3 | 1.9232 (16) | Cu1—O4 | 2.3879 (19) |
Cu1—O3i | 1.9342 (16) | O1—Cu1ii | 1.9923 (18) |
Cu1—O2 | 1.9747 (18) | O3—Cu1ii | 1.9342 (16) |
Cu1—O1i | 1.9923 (18) | | |
| | | |
O3—Cu1—O3i | 176.35 (5) | O2—Cu1—O1i | 173.75 (8) |
O3—Cu1—O2 | 91.80 (8) | O3—Cu1—O4 | 94.23 (7) |
O3i—Cu1—O2 | 85.48 (7) | O3i—Cu1—O4 | 88.44 (7) |
O3—Cu1—O1i | 90.40 (8) | O2—Cu1—O4 | 94.71 (8) |
O3i—Cu1—O1i | 92.06 (8) | O1i—Cu1—O4 | 90.95 (8) |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x+1, y−1/2, −z+3/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H41···O3iii | 0.85 | 1.88 | 2.725 (3) | 169 |
O3—H31···O1i | 0.85 | 2.48 | 2.779 (2) | 102 |
O3—H31···O2ii | 0.85 | 2.34 | 2.653 (2) | 102 |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x+1, y−1/2, −z+3/2; (iii) −x+1, −y+1, −z+1. |
Metallosupramolecular species assembled from transition metal and organic ligands have attracted great interest because of not only their intriguing structural diversities but also their potential uses as functional materials (Leininger et al., 2000; Robin & Fromm, 2006; Steel, 2005). The effective and facile approach for the synthesis of such complexes is still the appropriate choice of well designed organic ligands as bridges or terminal groups (building blocks) with metal ions or metal clusters as nodes; this method, so far, has been at an evolutionary stage, with the current focus mainly on understanding the factors that determine the crystal packing as well as exploring relevant potential properties (Ye et al., 2005). Among various ligands, the versatile carboxylic acid ligands exhibiting diverse coordination modes, especially for benzene-based carboxylic acids, have been used and well documented in the preparation of various carboxylate-containing CuII metal-organic complexes, such as benzoic acid (HBA, see Scheme II) (Bkouche-Waksman et al., 1980; Kawata et al., 1992; Koizumi et al., 1963; Gavrilenko et al., 2005) and 1,4-benzenedicarboxylic acid (Du et al., 2005; Hu et al., 2006).
In comparison with the aforementioned benzene-based carboxylic acid ligands, however, far less common has been the investigation of naphthalene- and anthracene-based carboxylic acids, such as naphthalene-1-carboxylic acid (HL) and anthracene-9-carboxylic acid (HACA) (see Scheme II). In general, such bulky aromatic carboxylic acid ligands have larger conjugated π-systems, and the steric hindrance of the bulky naphthalene and anthracene ring systems may affect the coordination abilities and modes of related carboxylate groups, leading to the formation of supramolecular structures that differ from those of related benzene-based carboxylic acid ligands. In our recent work, HL and HACA have been used successfully to construct a series of novel CuII, CoII, NiII, MnII and CdII complexes having mononuclear, dinuclear, tetranuclear, one-dimensional and two-dimensional structures, and exhibiting interesting magnetic and luminescence properties (Liu et al., 2006, 2007; Zou et al., 2005).
To further explore the coordination architectures of the L ligand bearing the bulky skeleton of the naphthalene ring system, in this research, a new CuII complex, (I), with HL was synthesized by taking advantage of the carboxylate bridging coordination abilities and the steric bulk of the naphthalene ring system. We report here the crystal structure of (I) and further compare it with the structurally related benzene- and anthracene-based CuII–carboxylate complexes whose crystal structures have been reported in the literature (Bkouche-Waksman et al., 1980; Kawata et al., 1992; Koizumi et al., 1963; Liu et al., 2007) .
Complex (I) consists of one-dimensional polymeric coordination chains containing only one kind of CuII coordination environment (Fig. 1). The asymmetric unit of (I) is composed of one CuII ion, one L ligand, one OH anion and one coordinated water molecule. Each CuII center is five-coordinated to two O atoms of carboxylate groups from two distinct L ligands and two O atoms from two OH- anions in the equatorial plane, as well as one O atom from one coordinated water molecule located at the axial position [Cu1—O4 = 2.3879 (19) Å; see Table 1]. In general, several parameters are often used to define the coordination geometry of the five-coordinated metal center, and one of the most common parameters is the τ factor defined by Addison et al. (1984) (τ = 0 for regular square pyramidal and τ = 1 for regular bpt geometry). The calculated τ value of (I) is 0.0432 for the CuII center, i.e. close to zero, indicating an almost ideal square-pyramidal coordination environment, and the CuII center deviates from the mean equatorial plane of the square pyramid [O1/O3/O1A/O3A; symmetry code: (A) 1 - x, 1/2 + y, 3/2 - z] towards the apical O4 atom of the coordinated water molecule by ca 0.0718 Å. Moreover, L in (I) adopts a bidentate syn–syn bridging coordination mode using two O atoms of the carboxylate group, which further bridge adjacent CuII centers to generate a one-dimensional chain along the [010] direction (Fig. 1).
In the crystal structure of (I), adjacent one-dimensional [Cu(L)(OH)(H2O)]nchains are arranged into a two-dimensional network running parallel to the (100) plane by inter-chain O—H···O hydrogen-bonding interactions between the coordinated water molecules and the carboxylate O atoms of the L ligands (see Fig. 2 and Table 2).
As typical aromatic carboxylic acid ligands, benzene-based carboxylic acids have been widely used to construct metal-organic coordination architectures, such as benzoic acid (HBA, see Scheme II) (Bkouche-Waksman et al., 1980; Kawata et al., 1992; Koizumi et al., 1963; Gavrilenko et al., 2005) and 1,4-benzenedicarboxylic acid (Du et al., 2005; Hu et al., 2006). So far, a one-dimensional CuII–benzoate complex [Cu(BA)](BA)(H2O)3]n (Koizumi et al., 1963; BA is benzoate, C6H5CO2) and two dinuclear CuII–benzoate complexes, [Cu2(BA)4(CH3OH)2](CH3OH) (Bkouche-Waksman et al., 1980) and [Cu2(BA)4(HBA)2] (Kawata et al., 1992), have been reported. However, in this work, where we use HL instead of HBA to react with Cu(NO3)2 under certain conditions, only one one-dimensional polymer, (I), was produced. When we futher used HACA, with a larger bulky skeleton of aromatic rings, instead of HL to react with Cu(NO3)2 under the same conditions, one dinuclear discrete structure analogous to that of copper acetate, [Cu2(ACA)4(CH3OH)2](CH3OH), was obtained (Liu et al., 2007). Thus, although the carboxylic acid coordination sites of HL, HACA and HBA are very similar, their coordination chemistry is obviously different, presumably as a result of the different skeletal bulk of the naphthalene, anthracene and benzene ring systems.
Our results, therefore, reveal that the steric bulk of different aromatic ring systems (naphthalene, anthracene or benzene) may play an important role in the formation of related metal-organic complexes. From the viewpoint of ligand design, this fact may offer the means to construct unique coordination architectures with specific potential properties just by means of the steric bulk of different aromatic skeleton. Bulky carboxylate ligands containing naphthalene or anthracene ring systems might be generally used with different d10 transition metal ions, such as Ag, Zn and Cd, for constructing other metal-organic complexes with luminescence properties; research into this possiblity is underway in our laboratory.