104
X.-F. Wang et al. / Journal of Molecular Structure 1128 (2017) 103e110
mixed solution of methanol and DMF (1:1). Yield 76%, m.p.
283e284 ꢁC. 1H NMR (DMSO-d6):
: 9.130 (s, 2H, imidazole-2),
d
N
N
N
N
N
N
8.653 (s, 2H, pyridazine), 7.388e8.384 (m, 8H, benzene); Anal.
Calcd for C18H12N6: C, 69.21; H, 3.87; N, 26.91; Found: C, 69.34; H,
3.56; N, 27.41. IR (cmꢀ1, KBr pellets): 3082(m), 3058(m), 2924(w),
2854(w), 2773(w), 2371(w), 1921(w), 1783(w), 1739(w), 1669(w),
1609(m), 1590(m), 1558(s), 1497(s), 1459(s), 1359(m), 1338(m),
1308(m), 1279(m), 1238(m), 1190(s), 1163(m), 1138(m), 1035(m),
992(m), 979(m), 962(m), 939(m), 884(m), 830(m), 769(s), 753(s),
732(s), 644(m), 623(m), 575(m), 538(m), 486(m), 427(m).
N
N
N
N
N
N
L2
L1
Scheme 1. The ligands L1 and L2 used in this work.
H2O$CH3OH}n (4), [Ni(L2)2(NO3)2]n (5) and {[Zn(L2)Cl2]$DMF}n (6)
were synthesized. All complexes were structurally characterized by
elemental analysis, IR spectra, single crystal X-ray diffraction and
powder X-ray diffraction(PXRD). Furthermore, the photo-
luminescence property and UVevis diffuse reflection spectrum of
complex 6 have been investigated and discussed.
2.3. Synthesis of complexes 1~6
2.3.1. Preparation of [Ni(L1)4(OH)2] (1)
A mixture of Ni(ClO4)2$6H2O (0.035 g, 0.1 mmol), L1 (0.021 g,
0.1 mmol), and distilled water (5 mL) was placed in a 25 mL Teflon-
lined stainless steel vessel and heated at 140 ꢁC for 2 days. After tꢀh1e
mixture had been cooled to room temperature at a rate of 5 ꢁC h
,
2. Experimental section
green crystals of 1 were obtained with a yield of 43% (based on L1).
Anal. Calcd (%) for C40H34N24O2Ni (%): C, 51.02; H, 3.64; N, 35.70.
Found: C, 50.30; H, 3.28; N, 35.52. IR (KBr pellets, cmꢀ1): 3572(m),
3389(m), 3150(m), 3115(m), 2591(w), 2558(w), 2511(w), 2417(w),
2338(w), 2212(w), 2015(w), 1913(w), 1872(w), 1809(w), 1580(s),
1523(s), 1480(s), 1370(m), 1319(s), 1242(s), 1097(s), 1065(s), 1032(s),
967(m), 934(m), 915(m), 837(m), 737(m), 653(m), 620(m), 493(m),
419(m).
2.1. Materials and general methods
The chemicals in organic synthesis and all solvents were
commercially available and used without further purification. FT-IR
spectra were measured with a Brucker Equinox 55 spectrometer on
KBr Pellets in the range of 4000e400 cmꢀ1. C, H and N elemental
analyses were carried out by Thermo Flash EA 1112-NCHS-O
analyzer. 1H NMR data were collected using an INOVA-400 NMR
spectrometer in DMSO medium at 25 ꢁC with TMS as the internal
reference. The X-ray powder diffraction (PXRD) was recorded on a
Rigaku D/Max-2500 diffractometer at 40 kV, 100 mA for a Cu-target
tube and a graphite monochromator. Luminescence spectra were
measured by a Hitachi F-4500 Fluorescence Spectrophotometer,
equipped with a Xe arc lamp excitation source and bandwidths of
2.5 nm at room temperature. Fluorescence lifetime data were ac-
quired on Fluorolog-3 Spectrophotometer equipped with nanoled
as the light source. UVeVis absorption spectra were obtained using
a Hitachi UV-3010 UVeVis Spectrophotometer.
2.3.2. Preparation of [Cu(L1)4(OH)2] (2)
A solution of L1 (0.021 g, 0.1 mmol) in MeOH (3 mL) was care-
fully layered on top of MeOH/H2O (10 mL, middle), and a solution of
Cu(BF4)2$6H2O (0.035 g, 0.1 mmol) in H2O (3 mL, bottom) at room
temperature. The blue block-shaped crystals were formed after 5
days with the evaporation of the filtrate. The crystalline product
was obtained after filtering and washed with distilled water (ca.
38% yield based on L1). Anal. Calcd (%) for C40H34N24O2Cu (%): C,
54.42; H, 3.88; N, 38.07. Found: C, 54.54; H, 3.82; N, 38.42. IR (KBr
pellets, cmꢀ1): 3601(m), 3384(m), 3155(m), 3118(m), 2870(w),
2788(w), 2738(w), 2592(w), 2530(w), 2418(w), 2339(w), 2212(w),
2339(w), 2212(w), 2083(w), 2009(w), 1914(w), 1872(w), 1809(w),
1716(m), 1581(s), 1522(s), 1481(s), 1370(m), 1321(s), 1243(s),
1067(s), 1033(s), 968(s), 942(m), 912(m), 838(m), 739(m), 652(m),
613(m), 493(m).
2.2. Preparation of ligands
2.2.1. Preparation of ligand L1
3,6-bis(imidazole-1-yl)pyridazine (L1) A mixture of imidazole
(3.4 g, 49.9 mmol) and sodium (1.2 g, 26.1 mmol) were dissolved in
THF (80 mL). After heating reflux for 40 min, a solution of 3,6-
dichloropyridazine (3.7 g, 24.8 mmol) in THF (10 mL) was added
to the mixture within 40 min. The mixture was refluxed for 4 h
under N2, then stirring for 30 min. After the reaction mixture was
cooled to ambient temperature. Poured reactor into ice water
mixture, an earthy yellow solid of L1 was obtained after filtering and
distilling off the filtrate, recrystallized from absolute ethanol to give
pure ligand L1 as white crystals, yield 80%, m.p. 281e282 ꢁC. 1H NMR
2.3.3. Preparation of [Cu(L1)2(SiF6)]n (3)
The synthesis procedure of 3 was similar to complex 2, except
for using CuSiF6$6H2O (0.031 g, 0.1 mmol) instead of
Cu(BF4)2$6H2O. The solution was allowed to stand for approxi-
mately two weeks, resulting in the formation of blue block-shaped
crystals of 3 that were obtained. Yield: 32% based on L1. Anal. Calcd
(%) for C20H16N12F6SiCu (%): C, 38.13; H, 2.56; N, 26.68. Found: C,
38.47; H, 2.28; N, 27.52. IR (KBr pellets, cmꢀ1): 3520(m), 3136(m),
2596(w), 240(w), 2350(w), 2216(w), 2026(w), 1915(w), 1639(m),
1580(s), 1497(s), 1454(s), 1376(m), 1310(s), 1278(s), 1248(m),
1147(m), 1121(m), 1102(m), 1076(s), 1037(m), 970(m), 859(m),
712(s), 650(s), 498(m), 473(m), 429(m).
(DMSO-d6):
(s, 2H, imidazole-5), 7.23 (s, 2H, imidazole-4); Anal. Calcd for
10H8N6: C, 56.60; H, 3.79; N, 39.60; Found: C, 56.75; H, 3.75; N,
d: 8.69 (s, 2H, imidazole-2), 8.48 (s, 2H, pyridazine), 8.11
C
39.54. IR (cmꢀ1, KBr pellets): 3176(w), 3145(m), 3109(m), 3047(m),
3018(m), 2946(m), 2782(w), 2621(w), 2526(w), 2408(w), 2214(w),
1991(w), 1903(w), 1795(w), 1727(w), 1692(w), 1645(w), 1577(s),
1519(s), 1490(s), 1459(s), 1371(m), 1321(s), 1277(m), 1237(m),
1163(m), 1106(m), 1059(m), 1031(s), 962(m), 903(m), 861(s), 823(s),
766(s), 749(s), 645(s), 613(m), 507(w), 487(m), 421(m).
2.3.4. Preparation of {[Cu(L2)(HCOO)2]·H2O·CH3OH}n (4)
A mixture of Cu(NO3)2·3H2O (0.024 g, 0.1 mmol), L2 (0.031 g,
0.1 mmol) was dissolved in 15 mL mixed solvent (H2O: DMF:
CH3OH ¼ 1:1:1). The solution was refluxed for 3 h and allowed to
evaporate for seven days and finally suitable blue block crystals
were formed. The crystalline product was obtained after filtering
and washed with distilled water (ca. 53% yield based on L2). Anal.
Calcd (%) for C21H20N6O6Cu (%): C, 48.88; H, 3.91; N,16.29. Found: C,
47.37; H, 3.35; N, 15.30. IR (KBr pellets, cmꢀ1): 3485(m), 3155(w),
2.2.2. Preparation of ligand L2
3,6-bis(benzimidazole-1-yl)pyridazine (L2) The synthetic
method of L2 is the same as the L1, except for using benzimidazole
instead of imidazole, then crude product were recrystallized by the