2010
K.R. Grunwald et al.
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thermally controlled cuvette holder. Infrared (IR) spectra were measured on a Bruker
ALPHA–P Diamant ATR-FTIR spectrometer.
2.2. Synthesis of 1–3
Caution! Although no problems were encountered in this work, transition metal
perchlorate complexes are potentially explosive and should be handled with proper
precautions.
2.2.1. Synthesis of 1. To a boiling solution of HL (50 mg, 0.15 mmol) in ethanol
(2 mL), solid zinc perchlorate hexahydrate (119 mg, 0.32 mmol) was added and boiling
was maintained for an additional 30 min. The clear, yellow solution was allowed to cool
to room temperature and was layered with diethyl ether to obtain a light yellow
microcrystalline powder. The material was isolated by filtration, washed with
diethyl ether, and dried under reduced pressure to yield 31 mg (34%) of
[{Zn2L(ꢀ3-OH)(H2O)}2](ClO4)4 (1). Single crystals suitable for X-ray diffraction
analysis were obtained by slow diffusion of diethyl ether into an ethanolic solution at
1
ꢁ20ꢀC. H NMR (300 MHz, DMSO-d6, 300 K): ꢂ ¼ 8.79 (m, 4 H, ArHPy þ N ¼ CH),
8.23 (t, J ¼ 7.5 Hz, 2H, ArHPy), 7.78 (m, 4H, ArH), 7.58 (s, 2H, ArHPh), 5.19 (s, 4H, N–
CH2), 4.17 (s, br, 2H, Zn–OH), 2.31 (s, 3H, Ph–CH3), 2.22 (s, br, 1H, Zn–OH–Zn). IR
(ATR, cmꢁ1): ꢃ ¼ 619 (s), 762 (m), 1047 (s), 1542 (m), 1610 (s), 1637 (s), 3448 (br, H2O).
Anal. Calcd for C42H44Cl4N8O22Zn4 (%): C, 35.62; H, 3.13; N, 7.91. Found (%):
C, 34.95; H, 3.26; N, 7.68.
2.2.2. Synthesis of 2. To a boiling solution of HL (50 mg, 0.15 mmol) in ethanol
(2 mL), solid zinc acetate (59 mg, 0.32 mmol) was added and boiling was maintained for
an additional 30 min after the reagent was dissolved. The clear, yellow solution was
allowed to cool to room temperature and was layered with diethyl ether to obtain a
yellow solid material, which was separated by centrifugation, washed with THF and
diethyl ether, and dried under reduced pressure to yield 51 mg (52%) of
[Zn2L(CH3COO)3] (2). 1H NMR (300 MHz, DMSO-d6, 300 K): ꢂ ¼ 8.73 (s, 2H,
N ¼ CH), 8.62 (d, J ¼ 5.2, 2H, ArHPy), 8.12 (dt, J ¼ 7.7, 1.4 Hz, 2H, ArHPy), 7.66
(d, J ¼ 7.7 Hz, 2H, ArHPy), 7.61 (dt, J ¼ 7.7, 1.4 Hz, 2H, ArHPy), 7.55 (s, 2H, ArHPh),
5.16 (s, 4H, N–CH2), 2.30 (s, 3H, Ph–CH3), 1.82 (s, 9H, 3CH3COO). IR (ATR, cmꢁ1):
ꢃ ¼ 642 (m), 1020 (m), 1045 (m), 1410 (s, CO2 symm str), 1559 (s, CO2 asymm str), 2925
(w), 3300 (br, H2O). Anal. Calcd for C27H28N4O7Zn2 ꢂ 6H2O (%): C, 42.70; H, 5.31;
N, 7.38. Found (%): C, 43.74; H, 5.70; N, 7.41.
2.2.3. Synthesis of 3. To a boiling solution of HL (50 mg, 0.15 mmol) in n-butanol
(2 mL), solid zinc chloride (44 mg, 0.32 mmol) was added. After a few seconds a
voluminous yellow precipitate started to form and boiling was maintained for an
additional 30 min. The suspension was allowed to cool to room temperature. The solid
material was separated by centrifugation and was washed with THF and diethyl ether,
1
and dried under reduced pressure to yield 80 mg (96%) of [Zn2LCl3] (3). H NMR
(300 MHz, DMSO-d6, 300 K): ꢂ ¼ 8.75 (s, br, 4H), 7.94 (m, br, 2H), 7.62 (s, br, 4H), 7.47
(s, 2H), 5.11 (s, br, 4H, N–CH2), 2.27 (s, 3H, Ph–CH3). IR (ATR, cmꢁ1): ꢃ ¼ 767 (s),