Anion-tuned self-assembly of zinc(II)-fluconazole complexes: Crystal structures, luminescent and thermal properties

Article abstract of DOI:10.1016/j.molstruc.2006.06.028

Four novel fluconazole-bridged Zn(II) complexes, [Zn(HFlu)Cl₂(DMF)]₂ (1), {[Zn(HFlu)₂(H₂O)₂](NO₃)₂·2DMF}_n (2), {[Zn(HFlu)₂(H₂O)₂](NO₃)₂}_n (3) and {[Zn(HFlu)(SCN)₂]·H₂O}_n (4) [HFlu = 2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)-propan-2-ol], have been synthesized and structurally characterized by X-ray diffraction method. The structure of dimeric complex 1 consists of 20-membered macrometallacyclic ring-like structure, in which the Zn(II) ion is in a five-coordinated distorted trigonal bipyramidal geometry with the Zn?Zn distance of 10.265(3) A? across the cis HFlu ligand. Complex 2 shows infinite 1-D macrocyclic double chain structure with the central Zn(II) ions being six-coordinated by four HFlu ligands and two apical water molecules and with the intrachain Zn?Zn distance of 10.722(3) A? across the trans HFlu ligand. The crystal structure of complex 3 is analogous to that of complex 2 with the intrachain Zn?Zn distance of 10.654(2) A?. The structure of complex 4 consists of infinite 1-D coordination polymeric chain with the tetrahedral coordination geometry of Zn(II) ion and with the intrachain Zn?Zn distance of 11.173(2) A? across the cis HFlu ligand. Complexes 1-4 show the similar fluorescence emission to the free HFlu ligand at ambient temperature and the thermal stabilities of the complexes have also been investigated.

Full text of DOI:10.1016/j.molstruc.2006.06.028

Journal of Molecular Structure 829 (2007) 161–167
www.elsevier.com/locate/molstruc
Anion-tuned self-assembly of zinc(II)–fluconazole complexes:
Crystal structures, luminescent and thermal properties
a,
a
a
b
Lei Zhang *, Yun Ling , Feng Peng , Miao Du
a
Department of Pharmaceutical Engineering, School of Chemical Engineering, South China University of Technology, Guangzhou 510640, PR China
b
College of Chemistry and Life Science, Tianjin Normal University, Tianjin 300074, PR China
Received 12 April 2006; received in revised form 17 June 2006; accepted 17 June 2006
Available online 14 August 2006
Abstract
Four novel fluconazole-bridged Zn(II) complexes, [Zn(HFlu)Cl2(DMF)]2 (1), {[Zn(HFlu)2(H2O)2](NO3)2Æ2DMF}n (2),
{[Zn(HFlu)2(H2O)2](NO3)2}n (3) and {[Zn(HFlu)(SCN)2]ÆH2O}n (4) [HFlu = 2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)-propan-
2-ol], have been synthesized and structurally characterized by X-ray diffraction method. The structure of dimeric complex 1 consists
of 20-membered macrometallacyclic ring-like structure, in which the Zn(II) ion is in a five-coordinated distorted trigonal bipyramidal
˚
geometry with the Znꢀ ꢀ ꢀZn distance of 10.265(3) A across the cis HFlu ligand. Complex 2 shows infinite 1-D macrocyclic double chain
structure with the central Zn(II) ions being six-coordinated by four HFlu ligands and two apical water molecules and with the intrachain
˚
Znꢀ ꢀ ꢀZn distance of 10.722(3) A across the trans HFlu ligand. The crystal structure of complex 3 is analogous to that of complex 2 with
˚
the intrachain Znꢀ ꢀ ꢀZn distance of 10.654(2) A. The structure of complex 4 consists of infinite 1-D coordination polymeric chain with the
˚
tetrahedral coordination geometry of Zn(II) ion and with the intrachain Znꢀ ꢀ ꢀZn distance of 11.173(2) A across the cis HFlu ligand.
Complexes 1–4 show the similar fluorescence emission to the free HFlu ligand at ambient temperature and the thermal stabilities of
the complexes have also been investigated.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Crystal structure; Fluconazole; Zn(II) complex; Self-assembly; Anion effect
1. Introduction
as an auxiliary ligand to the metal sites to influence on the
dimensionality of the coordination polymers [20–24]. Apart
from these, the weak interactions (hydrogen bonding, p–p
and hydrophobic interactions) are also significant to stabi-
lize the structure and/or to form the high dimensional
structures [12,25–29].
Poly(triazolyl)alkanes are attractive ligands for the
design of the novel inorganic–organic hybrid frameworks
and exhibit an extensive ability to bridge metal ions to
afford polynuclear complexes [30–33]. We promote the
poly(triazolyl)alkanes to the polyfunctional bis-triazole
Crystal engineering has generated considerable interests
due to the intriguingly aesthetic architectures, and/or the
potential functional materials [1–11]. Self-assembly is one
of the most successful approaches to construct the coordi-
nation supramolecules by the assembly of metal ions with
the polyfunctional organic ligands (such as pyrazine, 4,40-
bpyridine, polycarboxylic acid and their analogues) as link-
ers [12–15]. The structure of the coordination polymer is
significantly influenced by the coordination preference
and geometry of the metal ions [16–19]. The anion can
act not only as a charge-compensating component, but also
fluconazole.
Fluconazole
[2-(2,4-difluorophenyl)-1,3-
bis(1,2,4-triazol-1-yl)-propan-2-ol, HFlu, Chart 1] is one
of the first-line popular drugs used to treat invasive infec-
tions [34,35], and would be an interesting candidate to
construct coordination polymers, since it combines the fea-
tures required for coordination to metal ions through two
*
Corresponding author. Fax: +86 20 8711 0234.
E-mail address: lzhangce@scut.edu.cn (L. Zhang).
0022-2860/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2006.06.028

162
L. Zhang et al. / Journal of Molecular Structure 829 (2007) 161–167
48%. Anal. Calcd. for C16H19Cl2F2N7O2Zn: C, 37.27; H,
F
5.08; N, 19.01. Found: C, 37.51; H, 5.52; N, 19.05. IR
(KBr pellet, cmꢁ1): 3277m, 3165w, 3126w, 1656s, 1619w,
1525m, 1420m, 1373m, 1278m, 1124s, 964m, 871m, 646m.
2.2.2. {[Zn(HFlu)2(H2O)2](NO3)2Æ2DMF}n (2)
The colorless block crystals of 2 suitable for X-ray anal-
ysis were obtained by a method similar to that of 1 except
that ZnCl2 was replaced by Zn(NO3)2Æ6H2O. Yield 64%,
Anal. Calcd. for C32H42F4N16O12Zn: C, 39.05; H, 4.30;
N, 22.77. Found: C, 39.21; H, 4.42; N, 22.97. IR (KBr pel-
let, cmꢁ1): 3126w, 1662s, 1618w, 1502m, 1382s, 1278m,
1136m, 966m, 858m, 669m.
F
N
N
N
N
N
OH
N
Chart 1. The chemical structure of fluconazole (HFlu).
2.2.3. {[Zn(HFlu)2(H2O)2](NO3)2}n (3)
The colorless block crystals of 3 were obtained in the
aqueous solution by a method similar to that of 2. Yield
52%, Anal. Calcd. for C26H28F4N14O10Zn: C, 37.26; H,
3.37; N, 23.40. Found: C, 37.01; H, 3.82; N, 23.22. IR
(KBr pellet, cmꢁ1): 3283m, 1619m, 1505m, 1384s, 1277m,
1128s, 967m, 870m, 858m, 675m, 654m.
terminal triazoles and for extended intermolecular interac-
tions (H-bonding functionality through alkoxyl group at
the central carbon site and p–p interaction through the
phenyl ring). Thus, the HFlu ligand is potential to construct
a diversity of coordination architectures upon the metal
complexation. In this work, we firstly describe the synthesis,
crystal structures, fluorescent and thermal properties of
four new Zn(II)–fluconazole complexes: [Zn(HFlu)
Cl2(DMF)]2 (1), {[Zn(HFlu)2(H2O)2](NO3)2Æ2DMF}n (2),
{[Zn(HFlu)2(H2O)2](NO3)2}n (3) and {[Zn(HFlu) (SCN)2]Æ-
H2O}n (4), which are anion dependent.
2.2.4. {[Zn(HFlu)(SCN)2]ÆH2O}n (4)
The colorless rhombic crystals of 4 suitable for X-ray
analysis were obtained in the aqueous solution by a method
similar to that of 1 except that ZnCl2 was replaced by
Zn(SCN)2Æ3H2O. Yield 37%. The crystal was not stable
at room temperature and easily lost the lattice water to
form powder after taken away from the mother liquid. Ele-
mental analysis for the complex was performed after drying
for 4 h at 120 °C. C15H12F2N8OS2Zn: C, 36.93; H, 2.48; N,
22.97; S, 13.12. Found: C, 36.54; H, 2.94; N, 22.57, S,
12.98. IR (KBr pellet, cmꢁ1): 3657w, 3126m, 2090s,
1616m, 1533s, 1502m, 1421m, 1286s, 1132s, 993m, 966m,
864m, 671m, 655s.
2. Experimental
2.1. Materials and physical measurements
All chemicals were commercially available and used as
received without further purification. Elemental analyses
for C, H, N and S were carried out by using a Vario EL
III Elemental Analyzer. Infrared spectra were recorded
on a Bruker Equinox 55 FT-IR spectrophotometer as
KBr pellets in the range of 4000–400 cmꢁ1. Electronic
absorption spectra were recorded on a Hitachi U-3010
spectrophotometer in the range of 190–1100 nm. Lumines-
cence spectra for solid samples and the solution were
recorded with a Hitachi F-4500 fluorescence spectropho-
tometer. Differential scanning calorimeter–thermogravime-
try analyses (DSC-TG) were performed on a simultaneous
SDT thermal analyzer (STA449C, Netzsch) under a flow of
N2 at a heating rate of 10 °C/min between ambient temper-
ature and 950 °C.
2.3. X-ray structure studies
Intensities of complexes 1–4 were collected on a Bruker
Apex II CCD diffractometer with graphite monochromated
˚
MoKa radiation (k = 0.71073 A) at 293 K. Semi-empirical
absorption corrections were applied by SADABS program
[36], and the SAINT program was utilized for integration
of the diffraction profiles [37]. The structures were solved
by direct methods using SHELXS program of the SHEL-
XL package and refined with SHELXL program [38,39].
The heavy atoms were located from the E-maps and other
non-hydrogen atoms in successive difference Fourier syn-
theses. The final refinements were performed by full-matrix
least-squares methods with anisotropic thermal parameters
for all non-hydrogen atoms on F2. The C-bound hydrogen
atoms were generated with assigned isotropic thermal
parameters, and those of water molecules were first located
in the difference electron density map and then placed in
their calculation positions with fixed thermal factors. Crys-
tallographic data and structure refinement for 1–4 are sum-
marized in Table 1.
2.2. Preparations of complexes 1–4
2.2.1. [Zn(HFlu)Cl2(DMF)]2 (1)
To a solution of ZnCl2 (0.5 mmol, 0.0684 g) in H2O
(4 mL) was added
a solution of HFlu (0.5 mmol,
0.1541 g) in DMF (5 mL). After refluxed for 60 min, the
solution was filtered and kept at room temperature. Single
crystals suitable for X-ray analysis were obtained by very
slow evaporation of the solvent after 1 month. Yield:

L. Zhang et al. / Journal of Molecular Structure 829 (2007) 161–167
163
Table 1
Crystal data and structure refinement information for 1–4
1
2
3
4
Empirical formula
Formula weight
Crystal system
Space group
C16H19Cl2F2N7O2Zn
515.65
Triclinic
P-1
C32H42F4N16O12Zn
984.19
Monoclinic
C2/c
C26H28F4N14O10Zn
838.00
Triclinic
P-1
C15H14F2N8O2S2Zn
505.83
Monoclinic
P21/c
˚
a (A)
8.8081(13)
10.7453(16)
11.7205(17)
79.454(2)
77.595(2)
87.350(2)
1065.1(3)
2
9.514(5)
19.218(9)
23.633(11)
90
91.612(8)
90
4320(3)
4
1.513
9.2306(16)
10.6540(18)
10.8611(18)
61.450(2)
73.159(2)
70.602(2)
873.8(3)
1
10.141(2)
13.969(3)
15.308(3)
90
104.190(3)
90
2102.3(7)
4
1.598
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V (A )
Z
Dcalc (g cmꢁ3
l(MoKa)(mmꢁ1
)
1.608
1.449
1.592
0.799
)
0.663
1.414
F(000)
524
2032
428
1024
h range (°)
2.37–25.02
ꢁ9/10
1.72–25.03
ꢁ11/11
ꢁ19/22
ꢁ21/28
2.16–25.1
ꢁ10/10
ꢁ12/9
2.00–25.03
ꢁ12/8
h
k
l
ꢁ12/12
ꢁ16/16
ꢁ18/18
ꢁ13/12
ꢁ12/11
Reflections collected/unique [Rint
Data/restraints/parameters
GOF
]
5822/3720 [Rint = 0.0114] 10,787/3809 [Rint = 0.0286] 4751/3032 [Rint = 0.0136] 11,244/3718 [Rint = 0.0278]
3720/0/274
1.058
0.0265/0.0717
0.0314/0.0733
0.389, ꢁ0.260
3809/3/304
1.068
0.0420/0.1011
0.0547/0.1093
0.529, ꢁ0.317
3032/0/251
1.080
0.0287/0.0718
0.0358/0.0741
0.198, ꢁ0.205
3718/3/272
1.034
0.0350/0.0799
0.0523/0.0873
0.456, ꢁ0.329
Ra/w Rb [I > 2r(I)]
Ra/w Rb (all data)
˚
Residuals (e/A)
P
P
a
R = (iFoj ꢁ jFci)/ jFoj.
P
P
2
2 1=2
b
2
2
wR ¼ ½ wðF o ꢁ F c Þ = wðF oÞ ꢃ
.
3. Results and discussion
DMF solution, which must be ligand-centered p–p*
transitions.
3.1. Syntheses and general characterizations
3.2. Structural descriptions
Complexes 1–4 were prepared by reacting the correspond-
ing zinc(II) salts with fluconazole ligand in the different sol-
vent media under mild condition. Complexes 1 and 4 have
1:1 metal/ligand composition and 1:2 metal/ligand one was
achieved for complexes 2 and 3, although the same metal/li-
gand molar ratio (1:1) was applied to the preparation pro-
cess. For complexes 2 and 3, only the solvent is different in
the preparation process. The IR spectra of complexes 1–4
matched well with the absorption bands of the characteristic
skeletal vibrations of fluconazole at 3126, ꢂ1618, 1278 (1286
for 4) and 966 cmꢁ1. On the other hand, several characteris-
tic bands were observed at 1656 cmꢁ1 attributed to the C@O
stretching vibration of DMF molecules in 1, at 1662 and
1382 cmꢁ1 attributed to DMF molecules and nitrate anions
in 2, and at 2090 cmꢁ1 attributed to the SCNꢁ anions in 4,
respectively. The C@O stretching vibration of lattice DMF
molecule in 2 (1662 cmꢁ1) was observed to red shift to
1656 cmꢁ1 due to its complexation to Zn(II) ion. The vibra-
tion of SCNꢁ at 2090 cmꢁ1 in 4, lower than 2100 cmꢁ1, sug-
gested a monodentate N-coordinated mode [40], which was
conformed by X-ray structural analysis (vide infra). Elec-
tronic spectra of complexes 1–4 were measured in the solid
state and aqueous solution. The UV/vis spectra show only
intense bands in the UV region, at 266 nm (e = 707.6 dm3
molꢁ1 cmꢁ1) and 261 (e = 745.6 dm3 molꢁ1 cmꢁ1) in the
[Zn(HFlu)Cl2(DMF)]2 (1). The structure of 1 consists
of M2L2 metallocyclic ring-like structure constructed by
two ZnCl2 units, two DMF molecules and two HFlu
ligands as shown in Fig. 1a. Two HFlu ligands are both
in cis coordination conformation to bridge two Zn(II)
centers through triazolyl N atoms. Each Zn(II) center is
pentacoordinated to one Clꢁ and two N atoms from
two HFlu ligands in the equatorial plane, and one O
atom of DMF molecule and one Clꢁ at the axial positions
to form
a distorted trigonal bipyramid. The axial
˚
Zn(1)–Cl(2) bond length [2.4729(8) A] is longer than the
equatorial Zn(1)–Cl(1) one [2.2270(7) A] (Table 2). The
˚
Zn(II) ion is displaced from the equatorial plane by
ꢁ
˚
0.1965(6) A towards the axial Cl ligand. The structural
parameter s is used to evaluate the coordination geometry
of pentacoordinated metal center and is 0.83 for Zn(1),
indicating a mediated distorted trigonal bipyramidal coor-
dination environment [41]. The HFlu ligand adopts cis
conformation to bridge two Zn(II) ions with intermetallic
˚
Zn(1)ꢀ ꢀ ꢀZn(1a) distance of 10.265(3) A, and the two ben-
zene ring planes are strictly parallel each other. The Cl(2)
anion is hydrogen-bonded to the hydroxyl group of HFlu
˚
(dOꢀ ꢀ ꢀCl(2) = 3.121 A) to form 1-D chain structure along a
axis (Table 3, Fig. 1b).

164
L. Zhang et al. / Journal of Molecular Structure 829 (2007) 161–167
a
b
Fig. 1. (a) The asymmetric structure of dimeric complex 1 with the atom numbering scheme. (b) One-dimensional chain of complex 1 through O–Hꢀ ꢀ ꢀCl
hydrogen-bonding interactions.
{[Zn(HFlu)2(H2O)2](NO3)2Æ2DMF}n (2). The crystal
Table 2
structure of 2 consists of 1-D cationic macrocyclic double
˚
chain structure [Zn(HFlu)2(H2O)2]2+ (Fig. 2a), nitrate
Selected bond distances (A) and angles (°) for 1–4
Complex 1
anions and lattice DMF molecules. Within the chain, the
Zn(1)–N(1)
Zn(1)–Cl(1)
Zn(1)–Cl(2)
N(1)–Zn(1)–N(6)#1 114.72(8)
N(6)#1–Zn(1)–Cl(1) 119.08(6)
N(6)#1–Zn(1)–O(2)
N(1)–Zn(1)–Cl(2)
Cl(1)–Zn(1)–Cl(2)
2.0423(19) Zn(1)–N(6)#1
2.0501(18)
2.3235(17)
central Zn(II) ion is six-coordinated with a trans octahedral
coordination environment, different from that in complex
1. The equatorial plane was defined by four N atoms from
four HFlu ligands with the average Zn–N distance of
2.2270(7)
2.4728(8)
Zn(1)–O(2)
N(1)–Zn(1)–Cl(1)
N(1)–Zn(1)–O(2)
Cl(1)–Zn(1)–O(2)
N(6)#1–Zn(1)–Cl(2)
O(2)–Zn(1)–Cl(2)
123.61(6)
78.88(7)
92.50(5)
90.95(6)
164.65(5)
˚
˚
82.20(7)
91.71(6)
102.82(3)
2.167(2) A, longer than that found in 1 [2.046(2) A]. The
apical positions were occupied by two O atoms of two
˚
water molecules with the same bond length of 2.103(2) A.
Complex 2
Zn(1)–O(2)
Zn(1)–N(1)
O(2)–Zn(1)–N(6)#2
N(6)#2–Zn(1)–N(1)
The cis angles in the octahedron fall in the range of
89.35(9)–90.65(9)°, which deviate slightly from the ideal
90°. The structural parameter, defined as the sum of the
deviations from 90° of the 12 cis angles [42], is 6.08 in this
case, which suggests a weak octahedral distortion of Zn(II)
coordination sphere. Although the HFlu ligand has the
trans conformation in 2, different form the cis conforma-
tion in 1, the HFlu ligand coordinates to two Zn(II) ions
as a bridging ligand and also form a 20-membered macro-
cyclic ring, which is further linked by Zn–N bonds to result
in a 1-D structure as shown in Fig. 2. The shortest intra-
chain and interchain Znꢀ ꢀ ꢀZn distances are 10.722(3) and
2.103(2)
2.184(2)
89.44(9)
89.69(9)
Zn(1)–N(6)#2
2.154(2)
90.65(9)
O(2)–Zn(1)–N(1)
Complex 3
Zn(1)–O(2)
Zn(1)–N(1)
N(6)#4–Zn(1)–O(2)
N(6)#4–Zn(1)–N(1)
2.1691(14) Zn(1)–N(6)#4
2.1422(15)
2.1352(15)
92.47(5)
89.19(6)
90.04(6)
N(1)–Zn(1)–O(2)
Complex 4
Zn(1)–N(7)
Zn(1)–N(6)#6
N(7)–Zn(1)–N(8)
N(8)–Zn(1)–N(6)#6 103.71(11)
N(8)–Zn(1)–N(1)
N(7)–C(14)–S(2)
1.923(3)
2.001(2)
Zn(1)–N(8)
Zn(1)–N(1)
1.945(3)
2.016(2)
116.49(12)
N(7)–Zn(1)–N(6)#6 117.30(11)
N(7)–Zn(1)–N(1) 109.28(11)
N(6)#6–Zn(1)–N(1) 105.48(9)
N(8)–C(15)–S(1) 177.7(3)
˚
9.514(3) A, respectively. The uncoordinated nitrate is
hydrogen-bonded to adjacent chains through one nitrato
O atom with hydroxyl group and coordinated water mole-
cule to extend the 1-D chains to a 2-D sheet structure
(Table 3, Fig. 2b). The lattice DMF molecules cling to
103.16(11)
178.2(3)
#1: ꢁx + 1, ꢁy + 1, ꢁz + 1; #2: x ꢁ 1/2, y ꢁ 1/2, z; #3 ꢁx + 1, ꢁy,
ꢁz + 1; #4: ꢁx, ꢁy + 1, ꢁz; #5: ꢁx, ꢁy, ꢁz; #6: x ꢁ 1, ꢁy + 3/2, z ꢁ 1/2.

L. Zhang et al. / Journal of Molecular Structure 829 (2007) 161–167
165
a
b
Fig. 2. (a) One-dimensional double-bridged chain of complex 2 with the atom numbering scheme. Anions and lattice DMF molecules were omitted for
clarity. (b) Supramolecular network in complex 2 through O–Hꢀ ꢀ ꢀO hydrogen-bonding interactions.
through two nitrato O atoms with hydroxyl group and
coordinated water molecules to form a 2-D sheet structure
(Table 3, Fig. 3).
Table 3
Selected intramolecular and intermolecular hydrogen-bonding interac-
tions in complexes 1–4
Complex D–Hꢀ ꢀ ꢀA
D–H Hꢀ ꢀ ꢀA Dꢀ ꢀ ꢀA \D–Hꢀ ꢀ ꢀA
{[Zn(HFlu)(SCN)2]ÆH2O}n (4). The structure of complex
˚
˚
˚
(A)
(A)
(A)
(°)
4
consists of infinite 1-D zigzag
polymeric
1
2
O(1)–H(1)ꢀ ꢀ ꢀCl(2)#1
0.82 2.31
0.97 2.91
0.97 2.93
3.121
3.682
3.706
3.428
171
137
138
157
[Zn(HFlu)(SCN)2]n coordination chain and lattice water
molecule (Fig. 4). Each Zn(II) ion is ligated by two triazole
C(3)–H(3A)ꢀ ꢀ ꢀCl(2)#1
C(5)–H(5B)ꢀ ꢀ ꢀCl(2)#1
C(16)–H(16B)ꢀ ꢀ ꢀF(1)#2 0.96 2.53
O(1)–H(1)ꢀ ꢀ ꢀO(3)#3
O(2)–H(2B)ꢀ ꢀ ꢀO(3)#4
O(2)–H(2A)ꢀ ꢀ ꢀO(6)#5
0.82 1.93
0.85 1.90
0.85 1.84
2.745
2.709
2.683
3.451
3.248
173
159
174
159
157
C(15)–H(15A)ꢀ ꢀ ꢀF(2)#6 0.96 2.54
C(16)–H(16)ꢀ ꢀ ꢀO(4)#6
0.93 2.37
3
4
O(1)–H(1)ꢀ ꢀ ꢀO(5)#7
O(2)–H(2A)ꢀ ꢀ ꢀO(5)#8
O(2)–H(2B)ꢀ ꢀ ꢀO(3)#7
C(1)–H(1A)ꢀ ꢀ ꢀO4#8
C(10)–H(10)ꢀ ꢀ ꢀO4#9
0.82 2.00
0.85 1.98
0.85 2.23
0.93 2.28
0.93 2.48
2.813
2.811
2.973
3.028
3.392
175
166
146
137
169
O(2)–H(2B)ꢀ ꢀ ꢀO(1)#4
O(1)–H(1)ꢀ ꢀ ꢀO(2)#4
C(6)–H(6)ꢀ ꢀ ꢀS(2)#10
0.85 2.24
0.82 2.03
0.93 2.91
2.769
2.769
3.78
120
150
157
Fig. 3. Supramolecular network in complex 3 through O–Hꢀ ꢀ ꢀO hydro-
gen-bonding interactions.
Symmetry transformations used to generate equivalent toms: #1: ꢁx,
ꢁy + 1, ꢁz + 1; #2: ꢁx + 2, ꢁy + 1, ꢁz; #3: ꢁx + 1/2, ꢁy + 1/2, ꢁz + 1;
#4: x, y, z; #5: x, y ꢁ 1, z; #6: ꢁx, ꢁy, ꢁz + 1; #7: ꢁx + 1, ꢁy + 1, ꢁz;
#8: x, y ꢁ 1, z; #8: x, y ꢁ 1, z; #9:ꢁx + 1, ꢁy + 1, ꢁz + 1; #10 ꢁx + 2,
ꢁy + 1, ꢁz + 1.
the 2-D structure through hydrogen bonding to the coordi-
nated water molecules.
{[Zn(HFlu)2(H2O)2] (NO3)2}n (3). The crystal structure
of 3 consists of 1-D cationic macrocyclic double chain
structure [Zn(HFlu)2(H2O)2]2+ and nitrate anions, which
is similar to complex 2. The average Zn–N distance in 3
˚
is 2.1387(15) A, slightly shorter than that in
2
˚
˚
(2.167(2) A). The apical Zn–O distance is 2.1691 (14) A,
larger than that of 2.103(2) A in 2. The structural parame-
˚
ter around the Zn ion [42] is 13.28, suggesting the stronger
octahedral distortion than that observed in 2. The uncoor-
dinated nitrate is hydrogen-bonded to the adjacent chains
Fig. 4. The asymmetric unit of one-dimensional chain of complex 4 with
the atom numbering scheme. The lattice water molecule was omitted for
clarity.

166
L. Zhang et al. / Journal of Molecular Structure 829 (2007) 161–167
nitrogen atoms from two HFlu ligands and two nitrogen
atoms from SCNꢁ anions to form a distorted tetrahedral
geometry. The average Zn–Ntriazole distance [2.008 A] is
has three weight loss regions: the first observed weight loss
in the range of 40–146 °C (5.0%) is in agreement with the
calculated value of 4.3% for the loss of two-coordinated
water molecules. The second weight loss in the range of
220–705 °C (71.0%) can be assigned to the removal of
two HFlu ligands (73.0%). Above 705 °C, the resulting
Zn(NO3)2 gradually also decomposed with the tendency
to form ZnO powder. Complex 4 continuously lost the
weight from the beginning with 1.8% of the total molecular
weight (Calc. 3.6%) up to 125 °C, which confirmed the phe-
nomenon during the preparation of the complex.
˚
slightly longer than the average Zn–NSCN distance
˚
[1.934 A], and the N–Zn–N angles fall in the range of
103.71(11)–117.30(11) ° (Table 2). The HFlu ligand con-
nects two Zn(II) ions in the cis conformation with the
˚
Znꢀ ꢀ ꢀZn distance of 11.173(2) A and the Znꢀ ꢀ ꢀZnꢀ ꢀ ꢀZn
angle of 167.54 (11)°. The shortest Znꢀ ꢀ ꢀZn interchain dis-
˚
tance in 4 is 7.182(2) A, being shorter than the intrachain
Znꢀ ꢀ ꢀZn distance. The lattice water molecules are hydro-
gen-bonded to the alkoxyl OH groups to accrete to the
1-D chain (Table 3).
Metal–organic polymeric complexes with d10 configura-
tion (Zn2+, Ag+, Cd2+ and so on) have been found to
exhibit photoluminescence properties. Here, the photolu-
minescence of complexes 1–4 in the solid state and in the
solution at room temperature was examined. The intense
emission for 1–4 occurs at 284 nm upon excitation at
261 nm, but the intensity shows slightly alteration com-
pared to that of free fluconazole ligand. The similar phe-
nomenon was found in the ZnCl2-HFlu system, which
shows different crystal structure from polymer 1 [44,45].
Therefore, the emission was thought to be originated from
a ligand-centered p–p* process of 2,4-difluorobenzyl group
without significant influence by charge transfer character
induced by the Zn(II) cation.
The C–Hꢀ ꢀ ꢀF(Cl) and Fꢀ ꢀ ꢀF interactions play important
roles in stabilizing the molecular packing in crystal engi-
neering, which are reviewed by Hulliger et al. recently
[43]. The C–Hꢀ ꢀ ꢀF(Cl) interactions observed in complexes
1 and 2 are listed in Table 3, which are weaker than the
classic hydrogen bonding interactions. It is very interesting
to stress that the Fꢀ ꢀ ꢀF interaction was only observed in 2
˚
with the Fꢀ ꢀ ꢀF distance of 2.576(6) A, and that no C–Hꢀ ꢀ ꢀF
and Fꢀ ꢀ ꢀF interactions were found in complexes 3 and 4.
The dihedral angles between the best planes defined by
the two triazoles and phenyl moieties of each HFlu ligand
are listed in Table 4. Complexes 1–4 demonstrated that
Zn(II) ions had the capacity to change the coordination
geometries from tetrahedron to trigonal bipyramid to octa-
hedron that are tuned by the anions, and the flexible HFlu
ligand fulfills the requirement of the coordination geometry
by the conformational change and the screw of the bis-tri-
azole groups.
4. Conclusion
By self-assembly of fluconazole with different Zn(II)
salts, three types of complexes with structural diversity
varying from discrete dimer to one-dimension were firstly
isolated. The fluconazole ligand shows good flexile nature
to bridge two Zn(II) ions through two triazolyl nitrogen
atoms with trans-/cis-conformations to fulfill the geometric
requirement of Zn(II) ions. This study also shows that
anions have great influence on the coordination geometries
of Zn(II) ions through binding to Zn(II) or acting as count-
eranions, which offers a good opportunity in controlling
the coordination networks. The fluorescence property of
complexes 1–4 does not alter compared to that of the free
fluconazole ligand because Zn(II) ions is far away from the
fluorescence center without the electronic interactions with
the luminescence center.
3.3. Thermal and luminescent properties
Thermogravimetric analysis (TGA) of complex 1 indi-
cated that 1 lost 12.1% of the total molecular weight at
263 °C, corresponding to the loss of the coordinated
DMF molecule (Calc. 14.2%) and gradually decomposed
until 950 °C. However, complex 2 lost 18.9% of total
molecular weight in the range of 69–211 °C, corresponding
to the loss of two lattice DMF and two-coordinated water
molecules (Calc. 18.5%). Then it decomposed to lose two
HFLu ligands in the 220–675 °C with an experimental loss
of weight of 61.4% (Calc. 62.2%), and above 675 °C, the
resulting Zn(NO3)2 incompletely decomposed to form
ZnO powder until 950 °C. The TGA curve of complex 3
Acknowledgments
We are thankful for the financial support of the Nation-
al Nature Science Foundation of China (No. 20501008)
and Guangdong Provincial Laboratory for Green Chemi-
cal Technology. M.D. acknowledges the financial support
from Tianjin Normal University.
Table 4
Selected dihedral angles (°) for complexes 1–4
Complex
Plane 1–Plane 2
Plane 1–Plane 3
Plane 2–Plane 3
1
2
3
4
100.1
106.9
91.9
54.5
43.3
43.7
54.3
46.3
37.1
48.4
61.6
Appendix A. Supplementary data
109.4
Crystallographic data for the structures described in this
paper have been deposited with the Cambridge Crystallo-
graphic Data Centre, CCDC Nos 602704–602707. Copies
Plane 1 defined by triazole ring: N(1)–C(1)–N(2)–N(3)–C(3).
Plane 2 defined by triazole ring: N(4)–N(5)–C(6)–N(6)–C(7).
Plane 3 defined by phenyl ring: C(8)–C(9)–C(10)–C(11)–C(12)–C(13).

L. Zhang et al. / Journal of Molecular Structure 829 (2007) 161–167
167
[23] C.-Y. Su, Y.-P. Cai, C.-L. Chen, F. Lissner, B.-S. Kang, W. Kaim,
Angew. Chem., Int. Ed. Engl. 41 (2002) 3371.
[24] M. Du, X.-H. Bu, Y.-M. Guo, H. Liu, S.R. Batten, J. Ribas, T.C.W.
Mak, Inorg. Chem. 41 (2002) 4904.
[25] A.J. Blake, N.R. Champness, P. Hubberstey, W.-S. Li, M.A.
Withersby, M. Schro¨der, Coord. Chem. Rev. 183 (1999) 139.
[26] G.R. Desiraju, Acc. Chem. Res. 35 (2002) 565.
[27] M. Gdaniec, W. Jankowski, M.J. Milewska, Angew. Chem., Int. Ed.
42 (2003) 3903.
of the data can be obtained free of charge on application to
The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (int.) +44 1223/336 033; e-mail: depos-
it@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.
2006.06.028.
[28] S. Kitagawa, K. Uemura, Chem. Soc. Rev. 34 (2005) 109.
[29] H.M. Keizer, R.P. Sijbesma, Chem. Soc. Rev. 34 (2005) 226.
[30] L. Yi, X. Yang, T. Lu, P. Cheng, Cryst. Growth Des. 5 (2005)
1216.
[31] B.L. Li, X. Zhu, J.H. Zhou, Y. Zhang, J. Coord. Chem. 58 (2005)
271.
References
[1] S.R. Batten, R. Robson, Angew. Chem., Int. Ed. 37 (1998) 1460.
[2] O.M. Yaghi, M. O’Keefe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J.
Kim, Nature 423 (2003) 705.
[3] M. Eddaoudi, D.B. Moler, H.-L. Li, B.-L. Chen, T.M. Reineke, M.
O’Keefe, O.M. Yaghi, Acc. Chem. Res. 34 (2001) 319.
[4] J.M. Lehn, Science 295 (2002) 2400.
[5] O. Eyans, W. Lin, Acc. Chem. Res. 35 (2002) 511.
[6] O. Ikkala, G. Brinke, Science 295 (2002) 2407.
[7] B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1629.
[8] M.J. Zaworotko, Chem. Commun. (2001) 1.
[9] O.M. Yaghi, H. Li, C. Davis, D. Richardson, T.L. Groy, Acc. Chem.
Res. 31 (1998) 474.
[10] P.J. Hagrman, D. Hagrman, J. Zubieta, Angew. Chem., Int. Ed. 38
(1999) 2638.
[32] J.H. Zhou, X. Zhu, Y.N. Zhang, Y. Zhang, B.L. Li, Inorg. Chem.
Commun. 7 (2004) 949.
[33] L.F. Tang, Z.H. Wang, J.F. Chai, W.L. Jia, Y.M. Xu, J.T. Wang,
Polyhedron 19 (2000) 1949.
[34] J.M. Ritter, L.D. Lewis, T.G.K. Mant, A Textbook of Clinical
Pharmacology, fourth ed., Arnold, London, 1999, p. 423.
[35] M.R. Caira, K.A. Alkhamis, R.M. Obaidat, J. Pharm. Sci. 93 (2004)
601.
[36] G.M. Sheldrick, SADABS, Program for Empirical Absorption
Correction of Area Detector: University of Go¨ttingen, Germany,
1997.
[11] S. Kitagawa, R. Kitaura, S.-I. Noro, Angew. Chem., Int. Ed. 43
(2004) 2334.
[37] SAINT, Version 4.0, Siemens Analytic X-ray Systems, Madison, WI,
1995.
[12] H.W. Roesky, M. Andruh, Coord. Chem. Rev. 236 (2003) 91.
[13] P.J. Stang, B. Olenyuk, Acc. Chem. Res. 30 (1997) 502.
[14] D.L. Caulder, K.N. Raymond, Acc. Chem. Res. 32 (1999) 975.
[15] C.-Y. Su, Y.-P. Cai, C.-L. Chen, M.D. Smith, W. Kaim, H.C.Z.
Loye, J. Am. Chem. Soc. 125 (2003) 8595.
[38] G.M. Sheldrick, SHELXS 97, Program for the Solution of Crystal
Structures: University of Go¨ttingen, Germany, 1997.
[39] G.M. Sheldrick, SHELXL 97, Program for the Refinement of Crystal
Structures: University of Go¨ttingen, Germany, 1997.
[40] L. Shen, Y.Z. Xu, J. Chem. Soc. Dalton Trans. (2001) 3413.
[41] A.W. Addison, R. Nageswara, J. Chem. Soc. Dalton Trans. (1984)
1349.
[16] J.-C. Bunzli, C. Piguet, Chem. Rev. 102 (2002) 1897.
¨
[17] M. Fujita, N. Fujita, K. Ogura, K. Yamaguchi, Nature 400 (1999) 52.
[18] S.A. Barnett, N.R. Champness, Coord. Chem. Rev. 246 (2003) 145.
[19] J.-K. Cheng, Y.-G. Yao, J. Zhang, Z.-J. Li, Z.-W. Cai, X.-Y. Zhang,
Z.-N. Chen, Y.-B. Chen, Y. Kang, Y.-Y. Qin, Y.-H. Wen, J. Am.
Chem. Soc. 126 (2004) 7796.
´
[42] P. Guionneau, C. Brigouleix, Y. Barransm, A.E. Goeta, J.-F. Letard,
J.A.K. Howard, J. Gaultier, D.C.R. Chasseau, Acad. Sci. Paris 4
(2001) 161.
[43] K. Reichenba¨cher, H.I. Suss, J. Hulliger, Chem. Soc. Rev. 34 (2005)
¨
[20] A. Erxleben, Coord. Chem. Rev. 246 (2003) 203.
[21] J.Y. Lu, Coord. Chem. Rev. 246 (2003) 327.
22.
[44] H. Han, Y. Song, H. Hou, Y. Fan, Y. Zhu, Dalton Trans. (2006)
[22] R.H. Groeneman, L.R. MacGillivray, J.L. Atwood, Inorg. Chem. 38
(1999) 208.
1972.
[45] Y. Li, Acad. J. GCP 17 (2001) 49.