W.W. Lestari et al. / Inorganica Chimica Acta 421 (2014) 392–398
393
stacking interactions are also important in the structural design of
porous networks [14]
with a heating rate of 10 °C/min under helium atmosphere. The
nitrogen adsorption isotherm at 77 K of 1 was obtained on an
ASAP-2000 (Micromeritics) instrument equipped with a high-reso-
lution pressure sensor. Prior to the isotherm measurements, the
sample was heated at 100 °C for 12 h and then at 300 °C for 12 h.
The magnetic susceptibility data were obtained in an external field
of B = 1 T in the temperature range of 2–330 K with an MPMS 7XL
SQUID magnetometer (Quantum Design).
The majority of linkers employed are p-conjugated organic mol-
ecules with suitable rigid backbones functionalized with carboxyl-
ate or N-heterocyclic (e.g., pyridyl) moieties [1a,7]. The free organic
ligands usually show emission (fluorescence) from the lowest
exited singlet state to the singlet ground state, either
p ?
p⁄ or
n ? p⁄ [9]. However, incorporation of these ligands as linkers in
coordination polymers leads to reduction of the nonradiative decay
rate and to increased fluorescence intensity, lifetimes, and quan-
tum efficiencies [9]; thus, in general the spectra show shifted,
broad emission bands and loss of fine structure compared to the
free ligand. In the solid state, the close proximity facilitates molec-
ular interactions. In coordination polymers based on non-emitting
metal cations, factors that influence the ligand-based lumines-
cence properties are, the orientation and the arrangement of the
linkers (e.g., the dihedral angle between the aromatic rings), as
well as the coordination environment within the network [9a].
Coordination polymers of transition metal ions with open shells
such as CuII, NiII, or CoII mostly quench the fluorescence generated
from the organic linker [15]. However, there are exceptions such as
[Ln2Ni(Hbidc)2(SO4)2(H2O)8]n (Ln = Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er,
Yb; H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid), which show
only partial quenching [16]. Even though luminescence quenching
is initially considered a disadvantage, it is of crucial importance for
the development of sensors, e.g., for oxygen sensing [17].
2.2. Crystal structure determination
X-ray data were collected with a Gemini-S CCD diffractometer
(Agilent Technologies) using MoK radiation (k = 0.71073 Å) and
a
omega scan rotation. Data collection and data reduction were done
with CrysAlis Pro including the program SCALE3 ABSPACK for
empirical absorption correction [47]. The structure of 1 was solved
with Sir-92 [48]. Anisotropic refinement of all non-hydrogen
atoms, except for non-coordinating solvent molecules (dmf), was
performed with SHELXL-97 [49]. All hydrogen atoms were calcu-
lated on idealized positions. After several attempts to locate all sol-
vent molecules, five extremely poorly defined dmf molecules were
removed from the input file and the hkl file was corrected with the
program SQUEEZE [50]. However, the SQUEEZE electron count of
91 electrons is related only to approximately 2.5 dmf molecules,
i.e., half of the originally estimated number. The calculated volume
of 292 Å3 for one of these dmf molecules appears to be much too
large. The reported and expected volume for one dmf molecule is
102 Å3 [51]. For this reason, the originally detected five extremely
poorly defined dmf molecules were used to calculate the formula,
F(000), and all other composition-dependent parameters of the
compound. The calculated molecular volume of 146 Å3 for the
dmf molecules is much closer to the expected value. Structure fig-
ures were generated with Diamond-3 [52].
Coordination polymers or MOFs containing CuII cations or Cu
clusters as nodes show a variety of coordination modes when con-
structing the secondary building unit (SBU) [5]: Cu3 triangle [18],
Cu2 paddle wheel [19], Cu4 rectangle [20] (distorted in the case
of CuI) [21], and Cu8 cube [22], Cu2 paddle-wheel structures with
four bridging carboxylato ligands based on modified phenyl [23],
biphenyl [24], and binaphthyl [25] groups and other linkers have
been reported [26]. Cu2 paddle-wheel structures typically have
additional weakly coordinating axial ligands such as water
[23b,c,24,25] or strongly coordinating dmf [23a]. On removal,
unsaturated Lewis acidic Cu centers are generated, and therefore
these MOFs were mainly employed in catalysis [24,25,27]. Besides
Cu2 moieties based on CuII, M2 or MM’ paddle-wheel structures
have also been observed with other metals [5], such as RuII,III
[28], MoII [29], RhII [30], FeII [31], NiII [32], CoII [32], CrII [33], ZnII
[19b,31b,32b,34], MnII, WII [35], OsIII [36], CdII [37], BiII [38], BiII/
RhII [39], PtIII [40], AlIII [41], InIII [42], PdII/CoII [43], PdII/MnII [43],
RhII/CuII [44], RhII/ZnII [44], PdII/ZnII [43], MnII/ZnII [45], MnII/CoII
[45], FeII/ZnII [45], and FeII/CoII [45].
Crystallographic data for {[Cu2(L)2(dmf)2]ꢀH2Oꢀ9dmf} (1):
C
149H155Cu2N11O24P4, M = 2734.80, triclinic, space group P1,
a = 10.1470(4), b = 19.2737(7), c = 19.5457(7) Å,
b = 100.137(3)°,
= 103.590(3)°, V = 3533.8(2) Å3, Z = 1, qcalcd
1.285 Mg mꢂ3 (MoK ) = 0.419 mmꢂ1. Least-squares refinement
a = 101.853(3)°,
c
=
,
l
a
based on 45370 collected (24883 independent) reflections and
1505 parameters led to convergence, with a final R1 = 0.0520
(I > 2r(I)), wR2 = 0.1313 (I > 2r(I)), Flack parameter = 0.016(8),
and GOF = 1.015. The crystal data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
The X-ray powder diffraction (PXRD) measurements were car-
ried out on a STOE STADI P diffractometer in the Debye–Scherrer
mode using CuK radiation (k = 1.5406 Å). The samples for these
We here report the synthesis of the chiral Cu-based coordina-
tion polymer {[Cu2(L)2(dmf)2]ꢀH2Oꢀ9 dmf}n (1) (L = (S)-4,40-bis
(4-carboxylatophenyl)-2,20-bis(diphenylphosphinoyl)-1,10-binaph-
thyl) and its catalytic, magnetic and optical properties.
a1
measurements were prepared in glass capillaries (outer diameter
0.5 mm).
2.3. Synthesis of {[Cu2(L)2(dmf)2]ꢀH2Oꢀ9dmf}n (1)
2. Experimental
Solvothermal synthesis of 1 was carried out in stainless steel
autoclaves with Teflon liner (Parr). The temperature programs
were applied in an oven ULE400 (Memmert) using the software
Celsius 2005 (Version 6.1). A mixture of dmf/H2O (3 mL/1 mL)
was added to H2L (20 mg, 0.022 mmol) and Cu(NO3)2ꢀ3 H2O
(20 mg, 0.083 mmol) in a 15 mL Teflon-lined autoclave. After addi-
tion of 3 drops of HCl (3 M, aq.) or 1 drop of concentrated HCl
(67%), the vial was capped and placed in an oven at 90 °C for three
days, followed by a cooling time of 72 h. Prismatic blue-green crys-
tals (20 mg, 33%) were obtained, isolated by filtration, and dried at
room temperature. Scale up was performed by using two 200 mL
PARR reactors: Cu(NO3)2ꢀ3 H2O (0.4 g, 1.66 mmol) and H2L (0.4 g,
0.45 mmol) in dmf (60 mL), water (20 mL) and 20 drops of concen-
trated HCl. Yield: 0.52 g, 42.3% (based on H2L). Anal. Calc. for 1 (%):
2.1. Materials and general methods
Commercially available reagents were used as purchased. (S)-
4,40-bis(4-carboxyphenyl)-2,20-bis(diphenylphosphinoyl)-1,10-bina-
phthyl (H2L) was prepared according to the literature procedure
[46]. For catalytic tests, solvents were dried prior to use using stan-
dard procedures, and compound 1 was activated under vacuum
(1 ꢁ 10ꢂ3 mbar, 300 °C, 3 h). The infrared spectra were recorded
on a Perkin-Elmer System 2000 FTIR spectrometer by using KBr
pellets in the range of 4000–400 cm–1. Elemental analysis was per-
formed with a Heraeus VARIO EL instrument CHN–O analyzer.
Thermal analyses were performed on a NETZSCH STA/QMS system
409/429–403 thermal analyzer from room temperature to 900 °C