Full Papers
standard. Solid-state 13C cross-polarization magic-angle spinning
(CP/MAS) NMR spectroscopy was performed by using a Bruker SB
Avance III 500 MHz spectrometer with a 4 mm double-resonance
MAS probe, a sample spinning rate of 7.0 kHz, a contact time of
2 ms, and pulse delay of 5 s. TGA was performed by using
a NETZSCH STA 449C system by heating samples from 25 to 8008C
Synthesis of BPOP-2
The same synthetic procedure as that of BPOP-1 was used except
that 1,3,5-tri(4-pinacolatoborolanephenyl)benzene was replaced by
tetrakis(4-pinacolatoborolanephenyl)methane (0.82 g, 1.0 mmol).
Yield: 0.42 g (72%). IR: n˜ =3048 (vw), 3026 (w), 2953 (vw), 2915
(vw), 1610 (w), 1592 (w), 1507 (vs), 1487 (vs), 1469 (s), 1433 (m),
1388 (w), 1338 (w), 1308 (w), 1264 (w), 1214 (w), 1175 (vw), 1102
(s), 1072 (m), 1018 (m), 892 (w), 808 (vs), 749 (w), 698 (vw), 660 (w),
631 (w), 592 (w), 516 cmÀ1 (w); elemental analysis calcd (%) for
(C41H36N4)n [(584.8)n]: C 84.20, H 6.21, N 9.58; found: C 63.99, H
5.05, N 7.37.
in a dynamic N2 atmosphere with a heating rate of 108CminÀ1
.
FTIR spectra were recorded with KBr pellets by using a PerkinElmer
Instrument. GC was performed by using a Shimadzu GC-2014
system equipped with a capillary column (RTX-5, 30 mꢁ0.25 mm)
using a flame ionization detector. Field-emission SEM was per-
formed by using a JEOL JSM-7500F instrument operated at an ac-
celerating voltage of 3.0 kV. TEM images were obtained by using
a JEOL JEM-2010 instrument operated at 200 kV. Elemental analysis
was performed by using an Elementar Vario MICRO Elemental ana-
lyzer. Inductively coupled plasma atomic emission spectroscopy
was performed by using a Jobin Yvon Ultima2 system. N2 adsorp-
tion and desorption isotherms were measured at 77 K by using
a Micromeritics ASAP 2020 surface area and porosimetry analyzer.
The samples were degassed at 808C for 10 h under conditions of
dynamic vacuum before analysis. The specific surface area was cal-
culated using the BET model over a relative pressure (P/P0) range
of 0.05–0.15. Pore size distributions were calculated from the ad-
sorption isotherms by the nonlocal density functional theory
(NLDFT) method. H2 adsorption isotherms were collected by using
an ASAP 2020 instrument at 77 K. CO2 adsorption isotherms were
collected by using the ASAP instrument at 273 and 298 K.
General procedure for the Knoevenagel condensation
reaction
BPOP-1 or BPOP-2 was added to a mixture of benzaldehyde deriva-
tive (0.25 mmol) and malononitrile (0.38 mmol) in toluene (1.0 mL).
After the mixture was stirred in a preheated oil bath (408C) in air
for the appropriate time, the resultant mixture was filtered. The fil-
trate was analyzed by GC and then concentrated under the re-
duced pressure. The crude products were further purified by TLC.
The identity of the products was confirmed by comparison with lit-
erature spectroscopic data.
Reusability of BPOP-2 in the Knoevenagel condensation
reaction
A mixture of BPOP-2 (19.2 mg), 4-nitrobenzaldehyde (75.6 mg,
0.5 mmol), and malononitrile (49.5 mg, 0.75 mmol) in toluene
(2.0 mL) was stirred at 408C in air for 6 h, the reaction mixture was
filtered, and the filtrate was analyzed by GC. The separated pale
yellow powder was washed thoroughly with dichloromethane,
dried in vacuo, and used for the next run with fresh substrates.
Computational methods
The hybrid Becke three-parameter Lee Yang Parr (B3LYP)[22] density
functional method in combination with the 6–31G* basis set was
employed to study the equilibrium geometries and electronic
properties of models BPOP-1-MC and BPOP-2-MC. The natural pop-
ulation analyses were calculated by using the NBO 3.1 module em-
bedded in the Gaussian 09 program.[23] The wavefunction analyses
were performed using Multiwfn, which is a multifunctional wave-
function analysis program developed by Lu et al. that can be
downloaded freely.[24] During the calculation process, the default
settings were used for all programs. All isosurface maps that in-
clude the electrostatic potential on the van der Waals (vdW) sur-
face were rendered by the VMD program.[25]
Acknowledgements
This work was financially supported by the 973 Program
(2011CBA00502) and the National Natural Science Foundation of
China (21401195, 21471151).
Keywords: heterogeneous catalysis
·
Lewis bases
·
microporous materials · nitrogen heterocycles · polymers
Synthesis of BPOP-1
[1] a) M. S. Perryman, M. E. Harris, J. L. Foster, A. Joshi, G. J. Clarkson, D. J.
[2] a) T. C. Keller, S. Isabettini, D. Verboekend, E. G. Rodrigues, J. Perez-Ram-
varez, A. M. Frey, J. H. Bitter, A. Segarra, K. P. de Jong, F. Medina, Appl.
[4] G. J. Hutchings, C. Xu, J. K. Bartley, D. I. Enache, D. W. Knight, Synthesis
2005, 19, 3468–3476.
[5] a) A. Pineda, A. M. Balu, J. M. Campelo, A. A. Romero, R. Luque, Catal.
A
mixture of 4,7-dibromo-1-methyl-1H-benzimidazole (0.58 g,
2.0 mmol), 1,3,5-tri(4-pinacolatoborolanephenyl)benzene (0.89 g,
1.3 mmol), and Pd(PPh3)4 (0.23 g, 0.2 mmol) in 1,4-dioxane (120 mL)
was degassed through three freeze–pump–thaw cycles and
purged with N2. An aqueous K2CO3 solution (4 mL, 2m) was added
to the above mixture, and the resultant mixture was further de-
gassed through three freeze–pump–thaw cycles and purged with
N2. The reaction mixture was stirred at 1108C for 24 h. The precipi-
tate was filtered and washed with excess water, methanol, and
acetone, respectively. The resultant pale yellow product was further
Soxhlet extracted with dichloromethane and then dried in vacuo
at 808C to give the target product. Yield: 0.33 g (50%). IR: n˜ =3022
(w), 2948 (vw), 2909 (vw), 2846 (vw), 1589 (s), 1492 (vs), 1428 (m),
1385 (m), 1335 (m), 1257 (m), 1100 (s), 1062 (m), 1003 (m), 935
(vw), 891 (vw), 807 (vs), 739 (w), 700 (w), 661 (w), 631 (w), 578 (vw),
514 cmÀ1 (w); elemental analysis calcd (%) for (C12H10N)n [(168.2)n]:
C 85.68, H 5.99, N 8.33; found: C 67.43, H 4.79, N 5.80.
[6] a) J. Gascon, U. Aktay, M. Hernandezalonso, G. Vanklink, F. Kapteijn, J.
&
ChemCatChem 0000, 00, 0 – 0
6
ꢀ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!