Inorganic Chemistry
Article
+
a
Scheme 1. Schematic Diagram of Ligand [H tcma] Cl and Synthetic Scheme of In -GL
3
12
aHCO2− groups are deleted for clarity.
no In-based discrete MOC reported until now, therefore,
construction of novel indium-based structures can not only
enrich the structural features but also enable fine functionaliza-
tion. In this paper, we synthesized a new tripodal tricarboxylate
Synthesis of {[In12(μ
12 3
3
-OH)
4
(HCO
2
)
24(tcma)
4
]·x(solvent)}
+
(
[In -GL]·x(solvent)). A mixture of [H tcma] Cl (0.06624 g, 0.1
mmol) and In(NO ) ·xH O (0.12 g, 0.4 mmol) was dissolved in
3
3
2
DMF (12 mL) in a Teflon-lined stainless steel autoclave, and then
concentrated nitric acid (0.1 mL) was added. The autoclave was
heated at 80 °C under autogenous pressure for 7 days, followed by
cooling to room temperature. Pure white octahedral crystals were
obtained after centrifugation and washing with DMF. Powder X-ray
diffraction of the as-synthesized sample shows it is a pure phase. Yield:
ligand, N,N,N-tris{(2′-carboxy[1,1′-biphenyl]-4-yl)methyl}-
+
methylammonium chloride ([H tcma] Cl), which has struc-
3
tural features of semirigidity, a charge-separated skeleton, a
degree of spatial confinement, and coordination direction. The
+
3+
−1
reaction of [H tcma ]Cl with In(NO ) in DMF in the
0.15 g, 60% based on In ion. IR (cm ): 3432 (br), 1600 (vs), 1473
3
3 3
(
m), 1386 (s), 1307 (m), 853 (s), 764 (s), 628 (s), 533 (w), 458 (m).
X-ray Structural Studies. The X-ray single-crystal diffraction data
presence of nitric acid afforded white octahedral crystals of the
complex {[In (μ -OH) (HCO ) (tcma) ]} (In -GL)
1
2
3
4
2
24
4
12
of In -GL were recorded on the BL17B beamline (λ = 0.72 Å) at the
1
2
(Scheme 1).
Shanghai Synchrotron Radiation Facility (SSRF) at 107 K. All
calculations were performed with Olex2 and SHELXL crystallographic
software packages. The structure was solved by standard direct
methods and refined by anisotropic approximation. The solvent
molecules were highly disordered. The diffused electron densities
resulting from these residual solvent molecules were removed from
the data set by using the SQUEEZE routine of PLATON. The solvent
molecules were calculated on the basis of a combined study of TGA
and the removed electron counts. The solvents are excluded from the
unit cell contents in the crystal data. The crystal data and
experimental details for In -GL are given in Table 1, and the
EXPERIMENTAL SECTION
Materials and Methods. All chemicals and solvents were
purchased from available commercial sources and used as received.
IR spectra were recorded as KBr pellets on a PerkinElmer FT-IR
spectrometer in the range 4000−450 cm . Thermogravimetric
analysis (TGA) was measured on a Labsys evo TG-DTA/DSC
thermal analyzer under a nitrogen atmosphere with a heating rate of 5
■
−
1
°C/min. Powder X-ray diffraction (PXRD) data were collected on a
Rigaku D/Max 2500 diffractometer (Cu Kα, λ = 1.5418 Å) and 2θ
ranging from 5 to 50°. The yield of isolated product was determined
1
2
selected bond distances and angles are shown in Table S1.
1
by GC-MS equipment (Agilent 5977B). H NMR spectra were
recorded on an AVANCE 3HD (400 MHz) instrument in DMSO-d6
RESULTS AND DISCUSSION
■
with Me Si as the internal standard. ESI-MS mass spectra were
4
recorded on a Bruker HCT mass spectrometer. Scanning electron
microscopy (SEM) and elemental mapping spectra were carried out
on a FEI Quanta 200 instrument (Oxford Instruments). Gas
adsorption−desorption measurements were acquired on a PS2-1001
surface area analyzer with a desorption temperature of 100 °C under
Single-crystal X-ray diffraction analysis indicates that this
compound crystallizes in the cubic Fd3
̅
space group and has a
tetrahedral cage structure. Its asymmetric unit contains one-
−
3+
third of the ligand, one μ -OH anion, one In ion, and two
3
formate groups (Figure 1). This tetrahedral cage consists of the
vacuum.
trimeric anionic unit [In (OH)(μ -CO ) (μ -HCO ) ] formed
+
3
2
2 3
2
2 3
Synthesis of the Ligand [H tcma] Cl. A 30% solution of
3
−
1
by three indium atoms sharing a central hydroxyl anion,
bridged respectively by three formates and three carboxylate
MeNH in ethanol (1 mL, ρ = 0.66 g mL , containing 6.38 mmol of
2
MeNH ) was added to a solution of 20 mL of dry CH CH OH
2
3
2
2
−
3+
groups from the [tcma] linkers (Figure 2). Each In ion is
terminated by a formate anion. These formate anions are likely
produced by the decomposition of DMF during the In -GL
containing 4′-(bromomethyl)biphenyl-2-carboxylic acid methyl ester
(
5.84 g, 19.14 mmol). After the solution mixture was refluxed at 80
°
C for 8 h with stirring, 10% NaOH aqueous solution (∼25 mL) was
1
2
added and the solution mixture was further refluxed for another 8 h.
formation reaction. The trimeric [In (μ -OH)(μ -CO ) (μ -
3 3 2 2 3 2
Then the reaction solution was cooled to room temperature. A
HCO ) ] unit can be thought as an evolution from the 6-
2
3
−
1
hydrochloric acid solution (1 mol L ) was added dropwise into the
reaction solution, adjusting the pH to 7, at which point white
precipitates appeared. The resulting white precipitates were washed
using CH Cl and then recrystallized in CH OH solution to produce
connected [In (μ -O)(μ -CO ) ] unit, of which three μ -CO
3
3
2
2 6
2
2
moieties are replaced by three μ -HCO groups and the central
2
2
μ -O is replaced by μ -OH. This indium-containing unit
3
3
2
2
3
+
1
[In (μ -OH)(μ -CO ) (μ -HCO ) ] performs as a 3-con-
white crystals. Yield: 2.67 g (60%). ESI-MS: 662.25 for [H tcma] . H
3 3 2 2 3 2 2 3
3
nected unit which has been observed for the first time in In-
based complexes. Meanwhile the geometric configuration of
NMR: δ 2.94 (3H), 4.58 (6H), 7.39 (3H), 7.45 (9H), 7.58 (9H),7.70
−
1
(
1
3H). IR (cm ): 3460(br), 1704(vs), 1470(s), 1372(s), 1256(s),
220(s), 1003(m), 912(s), 847(s), 759(s), 534(s), 416(w).
2
−
the ligand [tcma] matches with this 3-connected trimeric
B
Inorg. Chem. XXXX, XXX, XXX−XXX
Azam, Khan
