Inorganic Chemistry
Article
Synthesis of Cu(II)-CP {[Cu(n-BuM)(H2O)](H2O)}n (Where n-
BuMH2 Represents n-Butylmalonic Acid). Copper(II) chloride
dihydrate (0.170 g, 1 mmol) and n-butyl malonic acid (0.160 g, 1
mmol) were dissolved in 25 mL of double-distilled water to give a
clear blue solution. The resulting blue colored solution was heated for
∼65 °C and stirred continuously for 6 h, and finally the filtrated blue
solution was kept for crystallization. After 15 days, deep blue block-
shaped suitable single crystals were collected under an optical
microscope for single-crystal X-ray analysis. The yield was 73% based
on Mn. Anal. Calcd for C7H12CuO5,H2O: C, 32.60; H, 4.65%. Found:
C, 32.59; H, 4.68%. IR absorption bands observed for Cu(II)-CP
(KBr pellet/cm−1) are 3426, 3289, 2952, 1552, 1456, 1340, 859, and
728 cm−1. The detailed crystallographic analysis is given in Figures S3
In this endeavor we have offered two synthesized CPs of
Zn(II) and Cu(II) [i.e., [Zn(n-BuM)(H2O)]n and {[Cu(n-
BuM)(H2O)](H2O)}n [where, n-BuMH2 = n-butylmalonic
Information for detailed crystallographic information on
Zn(II)- and Cu(II)-CP). A specific β-hydroxy ketone type
organic compound64 including 2-(hydroxy(4-nitrophenyl)-
methyl)cyclohexanone and its derivatives are exploited as the
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source of the Csp −Csp σ bond along with associated ketones.
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Our synthesized Zn(II)-CP instantaneously cleaves the Csp −
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Csp σ bond of 2-(hydroxy(4-nitrophenyl)methyl)-
cyclohexanone and its derivatives, and it leads to the formation
of corresponding benzoic acid derivatives and cyclohexanol as
the reduced product without the addition of any external
reducing agent under aerobic conditions. The CP packed
microcolumn-based filtration technique has been employed for
this process and several β-hydroxy ketones (e.g., 2-(hydroxy(4-
nitrophenyl)methyl)cyclohexanone and its derivatives) were
directly passed through the CP-packed microcolumn to cleave
RESULTS AND DISCUSSION
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Crystallographic and Microstructural Analyses of
Zn(II) and Cu(II)-CP. Single-crystal X-ray diffraction study
shows the crystallographic structural description of the
synthesized CPs of Zn(II) (see Figure S1 for ORTERP and
ORTERP and Figure S4 for structural patterns). Each Zn(II)-
center (Zn1) of 2-D Zn(II)-CP shows a penta-coordinated
geometry with oxygen donor sites from one chelating type n-
butylmalonate dianionic ligand (O2 and O3), two bridging
type O-donating binding modes of two adjacent oxygen atoms
(O1 and O4) of two different n-butylmalonate ligands, along
with one coordinated water molecule (O1W). Because of the
simultaneous binding modes of n-butylmalonate ligand toward
the Zn(II)-center, ultimately a 2-D sheetlike architecture
parallel to the crystallographic ab plane has been observed in
the solid state of Zn(II)-CP (see Figure S2).
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the Csp −Csp σ bond and for the simultaneous reduction of the
associated ketone to alcohol. However, the Cu(II)-CP is totally
noninteractive with the β-hydroxy ketone compounds in this
process.
EXPERIMENTAL SECTION
Materials. All chemicals were purchased from Sigma-Aldrich and
Merck and were used without any further purification. Double-
distilled water was used throughout the reaction.
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Characterization. pH measurements were performed using a
Mettler-Toledo pH meter. Elemental analysis (C, H, N) was carried
out using a PerkinElmer 2400 CHNS/O elemental analyzer. Suitable
single crystals of the Cu(II)- and Zn(II)-CP were mounted on a
Bruker SMART diffractometer equipped with a graphite mono-
chromator and Mo Kα (λ = 0.71073 Å) radiation. Electrospray
ionization mass spectroscopy (ESI-MS) experiments were carried out
on a Water’s QtoF Model YA 263 spectrometer in positive ion ESI
mode. FESEM images were obtained using a Carl Zeiss SUPRA 55VP
FESEM instrument. EDX studies were performed with the Oxford
Instruments X-Max with INCA software coupled to the FESEM
instruemnt. 1H NMR and 13C NMR spectral data were collected on a
Bruker 400 MHz instrument. For NMR spectra, CDCl3 and D2O
were used as the solvent using TMS as an internal standard. Chemical
shifts are expressed in δ ppm units. Solid-phase IR spectroscopy was
measured on Shimadzu FTIR-8400S spectrometer between 400 and
4000 cm−1, using the KBr pellet method. TG measurements were
carried out using a TG analyzer of Pyris Diamond TG/DTA
(PerkinElmer, STA 6000). PXRD patterns have been collected
through the instrument made of Rigaku, MiniFlex II with Cu Kα
radiation.
Synthesis of Zn(II)-CP [Zn(n-BuM)(H2O)]n (Where n-BuMH2
Represents n-Butylmalonic Acid). Zinc(II) acetate dihydrate
(0.219 g, 1 mmol) and n-butylmalonic acid (0.160 g, 1 mmol) were
dissolved in 25 mL of double-distilled water to give a clear colorless
solution. The resulting colorless solution became a blur solution when
diethanolamine (105 μL, 1 mmol) was applied. The dilute
hydrochloric acid was added until the blur solution became clear;
the solution was heated for ∼70 °C and stirred continuously for 6 h,
and the pH of the solution was adjusted to 1.98 using an aqueous
solution of NaOH and HCl. Finally, the filtrated clear colorless
solution was kept for crystallization. After 15 days, white block-shaped
suitable single crystals were collected under an optical microscope for
single-crystal X-ray analysis. The yield was 73% based on Mn. Anal.
Calcd for C7H12O5Zn: C, 34.78; H, 4.97%. Found: C, 34.70; H,
4.98%. IR absorption bands observed for Zn(II)-CP (KBr pellet/
cm−1) are 3457, 3385, 2925, 1590, 1428, 1373, 832, and 731 cm−1.
Crystallographic study also reveals the penta-coordinated
geometry of the Cu(II)-center has also been observed in the
case of Cu(II)-CP in the solid state (see Figure S4). Each
Cu(II)-center (Cu1) of Cu(II)-CP is connected with one
metal-chelating n-butylmalonate ligand (O1 and O3) along
with two bridging type metal-coordinating n-butylmalonate
ligands (O2 and O4) and one metal-coordinated water
molecule (O5). However, in comparison to Zn(II)-CP, there
is an extra free guest water molecule (O6) connected with the
Cu(II)-center through hydrogen-bonding interactions within
the crystal system of Cu(II)-CP. Similar to the Zn(II)-CP, the
simultaneous binding features of n-butylmalonate ligand with
Cu(II)-centers also direct the formation of 2-D coordination
polymeric network parallel to the crystallographic ab plane in
the solid-state of Cu(II)-CP (see Figure S4).
FESEM microstructural analysis of the Zn(II)-CP shows a
sedimentary rock-type architecture constructed by stacked
Figure 1. (a) FESEM microstructural image of sedimentary rock-like
architecture Zn(II)-CP in solid-state; (b) 2-D sheets of Zn(II)-CP
parallel to crystallographic ab plane. (Detailed structural description
B
Inorg. Chem. XXXX, XXX, XXX−XXX