Multifunctional, defect-engineered metal-organic frameworks with ruthenium centers: Sorption and catalytic properties

Article abstract of DOI:10.1002/anie.201311128

A mixed-linker solid-solution approach was employed to modify the metal sites and introduce structural defects into the mixed-valence Ru ^II/III structural analogue of the well-known MOF family [M ₃^II,II(btc)₂] (M=Cu, Mo, Cr, Ni, Zn; btc=benzene-1,3,5-tricarboxylate), with partly missing carboxylate ligators at the Ru₂ paddle-wheels. Incorporation of pyridine-3,5-dicarboxylate (pydc), which is the same size as btc but carries lower charge, as a second, defective linker has led to the mixed-linker isoreticular derivatives of Ru-MOF, which display characteristics unlike those of the defect-free framework. Along with the creation of additional coordinatively unsaturated sites, the incorporation of pydc induces the partial reduction of ruthenium. Accordingly, the modified Ru sites are responsible for the activity of the defective variants in the dissociative chemisorption of CO ₂, the enhanced performance in CO sorption, the formation of hydride species, and the catalytic hydrogenation of olefins. The defect engineering in Ru-based metal-organic frameworks (MOFs) at coordinatively unsaturated metal centers (CUS) induces partial reduction of the metal nodes and leads to properties that are absent for the parent MOF, such as dissociative chemisorption of CO₂ and enhanced sorption capacity of CO. The modified MOFs offer new perspectives as multifunctional materials whose performance is controlled by design of the defects.

Full text of DOI:10.1002/anie.201311128

Angewandte
Chemie
DOI: 10.1002/anie.201311128
Metal–Organic Frameworks
Multifunctional, Defect-Engineered Metal–Organic Frameworks with
Ruthenium Centers: Sorption and Catalytic Properties**
Olesia Kozachuk, Ignacio Luz, Francesc X. Llabrꢀs i Xamena, Heshmat Noei, Max Kauer,
H. Bauke Albada, Eric D. Bloch, Bernd Marler, Yuemin Wang,* Martin Muhler, and
Roland A. Fischer*
Abstract:
A
mixed-linker solid-solution approach was
ideally, exactly the same coordination environment. CUS are
commonly generated when solvent molecules ligating metal
centers are removed during activation, for instance, at the
axial positions of paddle-wheel units in [M3II,II(btc)2] (M =
Cu,[3] Mo,[4] Cr,[5] Ni,[6] or Zn;[7] btc = benzene-1,3,5-tricarbox-
ylate). Meanwhile, a particular challenge is to enhance the
accessibility, even lower the coordination number, and thus
modify the local structure and proximate space with respect to
the intrinsic metal ion framework sites by the introduction of
so-called “structural point defects” originating from partly or
even completely missing linker(s) and connections between
the metal nodes. The introduction of such defects should,
however, not compromise the overall integrity and robustness
of the framework.[8] The modified CUS are likely to behave
differently from the parent CUS and are expected to offer
novel opportunities for modulating the catalytic activity and
sorption behavior of MOFs. The presence of defects in the
MOF can have significant effects on the catalytic properties of
the material. These defects can come simply from an
imperfect crystallization of the MOF,[9] or be created in
a controlled manner by the introduction of auxiliary ligands
with missing carboxylate group(s).[10,11]
employed to modify the metal sites and introduce structural
defects into the mixed-valence RuII/III structural analogue of the
well-known MOF family [M3II,II(btc)2] (M = Cu, Mo, Cr, Ni,
Zn; btc = benzene-1,3,5-tricarboxylate), with partly missing
carboxylate ligators at the Ru2 paddle-wheels. Incorporation of
pyridine-3,5-dicarboxylate (pydc), which is the same size as btc
but carries lower charge, as a second, defective linker has led to
the mixed-linker isoreticular derivatives of Ru-MOF, which
display characteristics unlike those of the defect-free frame-
work. Along with the creation of additional coordinatively
unsaturated sites, the incorporation of pydc induces the partial
reduction of ruthenium. Accordingly, the modified Ru sites are
responsible for the activity of the “defective” variants in the
dissociative chemisorption of CO2, the enhanced performance
in CO sorption, the formation of hydride species, and the
catalytic hydrogenation of olefins.
T
he great diversity and modularity of metal–organic frame-
works (MOFs) suggest that they may compete with tradi-
tional porous materials for many applications.[1] Many pro-
cesses at MOFs involve interactions between metal sites and
guest molecules. Thus, the generation and control of reactive,
coordinatively unsaturated sites (CUS) within the molecular
scaffolds is highly desirable.[2] Generally, MOFs result from
the self-assembly of inorganic and organic building blocks to
form porous and highly ordered crystalline solids: all metal
ions are kept by the linkers at fixed positions in a lattice in,
Here, we report on a series of defect-engineered variants
D1–D4 (Figure 1) derived by framework incorporation of
defect-generating linkers into the parent RuII/III mixed-
valence compound [Ru3(btc)2Cl1.5] (1).[12] We demonstrate
that multifunctional properties of D1–D4 are enhanced or
even absent with respect to 1, and ranging from quite unusual
[*] O. Kozachuk, Prof. Dr. R. A. Fischer
E. D. Bloch
Chair of Inorganic Chemistry II, Ruhr-University Bochum
Universitꢀtsstrasse 150, 44801 Bochum (Germany)
E-mail: roland.fischer@ruhr-uni-bochum.de
Department of Chemistry
University of California, Berkeley (USA)
Dr. B. Marler
I. Luz, Dr. F. X. Llabrꢁs i Xamena
Faculty of Geosciences
Instituto deTecnologꢂa Quꢂmica (ITQ)
Universidad Politꢁcnica de Valencia
Institute of Geology, Mineralogy and Geophysics
Ruhr-University Bochum (Germany)
Consejo Superior de Investigaciones Cientꢂficas
Avenida de los Naranjos s/n, 46022 Valencia (Spain)
[**] O.K. acknowledges Ruhr-University Research School (http://
www.research-school.rub.de) for admission and additional support
of her PhD project. I.L. and F.X.L.X. acknowledge support by
Consolider-Ingenio 2010 (project MULTICAT) and the “Severo
Ochoa” program.
Dr. H. Noei, Dr. Y. Wang, Prof. Dr. M. Muhler
Laboratory of Industrial Chemistry
Ruhr-University Bochum (Germany)
M. Kauer, Dr. Y. Wang
Supporting information for this article (synthesis of D1–D4 as well
as details of the analytical and characterization methods, full PXRD,
FTIR, TG, SEM, BET, far-IR, XPS, UHV-FTIR, HPLC, 1H NMR
analysis, elemental analysis (Ru, C, H, N, Cl), and sorption and
catalytic data) is available on the WWW under http://dx.doi.org/10.
1002/anie.201311128.
Chair of Physical Chemistry I, Ruhr-University Bochum
Universitꢀtsstrasse 150, 44801 Bochum (Germany)
E-mail: wang@pc.rub.de
Dr. H. B. Albada
Chair of Inorganic Chemistry I—Bioinorganic Chemistry
Ruhr-University Bochum (Germany)
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

.
Angewandte
Communications
and Cl2p peaks (at 198.4 and 200.0 eV).[12] Along with the
C1s and O1s peaks of carboxylate species at 288.5 and
532.1 eV, respectively, the N1s peak at 400.2 eV is observed,
which originates only from pydc. Importantly, on the basis of
the O1s data, Ru oxide impurities are ruled out. These XPS
data together with elemental analysis data (Tables S2 and S3
in the Supporting Information) and further analytical evi-
dence (Figures S9–S12 in the Supporting Information) sup-
port the incorporation of pydc in the framework, resulting in
randomly distributed reduced, mixed-valence Ru2 paddle-
wheel units in which pydc partly replaces the parent btc and
with or without (residual) counter ion(s) or ligands at the
axial Ru sites (Figure 1).
CO adsorption isotherms at 298 K were recorded to
investigate the effect of the pydc incorporation on the
sorption capacity and showed an increased uptake. For
example, activated D3 displayed
a total uptake of
3.88 mmolgꢀ1, whereas the parent 1 had a 28% lower
uptake value of 2.8 mmolgꢀ1 (Figure S13 and Table S4 in
the Supporting Information). Hence, to gain more detailed
insight, the CO adsorption was monitored in situ by UHV-
FTIR spectroscopy at 90 K (Figures S14 and S15 in the
Supporting Information).[14] Interestingly, two new intense
bands at lower wavenumbers are seen at 2000 and 2039 cmꢀ1
for D1–D3, which are absent for the parent 1[12b] and are
highly sensitive to the doping level of pydc. These pronounced
red-shifted bands are characteristic for various CO species
adsorbed on Rud+ (0 < d < 2) centers (Table 1). Temperature-
dependent CO desorption experiments display the fast
decrease of the higher-lying bands at 2171 and 2118 cmꢀ1
upon heating. Their complete disappearance at 130 K and
190 K indicates the weak binding of (CO)Ru3+ and the
comparatively stronger binding of (CO)Ru2+, respectively.
Figure 1. Defect-engineered [Ru3(btc)2ꢀx(pydc)xXy] (X=Cl, OH, OAc;
x=0.1 (D1), 0.2 (D2), 0.6 (D3), 1 (D4); 0ꢁyꢁ1.5 (left) and parent
[Ru3(btc)2Cl1.5] (1) (right).
CO2!CO dissociative chemisorption (“reduction”) at 90 K
under ultrahigh-vacuum conditions (UHV) to hydrogen
splitting (Ru-H formation) at ambient conditions and related
hydrogenation catalysis.
The concept of mixed-linker solid solutions[13] was applied
to obtain the single-phased [Ru3(btc)2ꢀx(pydc)xXy] (D1–D4)
by using mixtures of H3btc and pyridine-3,5-dicarboxylic acid
(H2pydc) in the synthesis (Figure 1). The (deprotonated)
linkers btc3ꢀ and pydc2ꢀ are quite similar in size and structure,
but pydc has one less carboxylate ligator site. The Cu
analogues [Cu3(btc)2ꢀx(pydc)xXy] (X = NO3ꢀ, etc.) had been
synthesized and studied previously.[8b] From inspection of the
powder X-ray diffraction patterns (PXRD) of the as-synthe-
sized and activated samples it is deduced that D1–D4 are
isostructural to the parent single-linker 1 as well as to
[Cu3(btc)2] (HKUST-1, MOF-199) and its btc/pydc mixed-
linker variants. The samples exhibit permanent microporosity
with surface area values similar to that of 1 (Figures S3–S6,
Table S1 in the Supporting Information). While in its X-ray
photoelectron spectrum (XPS) the parent 1 features spin–
orbit doublet peaks (Ru3d5/2 and 3d3/2 region) at 281.5 and
285.7 eV, as well as at 282.5 and 286.7 eV characteristic for the
RuII and RuIII species,[12] an extra doublet at about 280.3 and
284.5 eV appears for D1–D3 (Figures S7 and S8; sample D4
was not measured). This new doublet increases gradually in
intensity and shifts to 280.0/284.2 eV when the concentration
of the defective linker pydc increases, indicating the presence
of additional Rud+ species that are more electron-rich than
RuII/III. The formation of reduced Rud+ is accompanied by the
attenuation of both the RuIII 3d peaks (at 282.5 and 286.7 eV)
Table 1: UHV-FTIR data for CO and CO2 adsorption at Ru species.
Sample
Band [cmꢀ1
]
Assignment
CO exposure
2171, 2137
2174, 2133
2045, 2002
2171, 2118
2039, 2000
parent Ru-MOF (1)
D1
(CO)Ru3+, (CO)Ru2+
(CO)Ru3+, (CO)Ru2+
(CO)Rud+
D3
(CO)Ru3+, (CO)Ru2+
(CO)Rud+
CO2 exposure
2335, 2272
2335, 2272
2039, 2000
2335, 2272
2039, 2000
parent Ru-MOF (1)
D1
(CO2)Ru2+, (CO2)Ru3+
(CO2)Ru2+, (CO2)Ru3+
(CO)Rud+
D3
(CO2)Ru2+, (CO2)Ru3+
(CO)Rud+
[a] Values in bold correspond to the frequencies of CO bound to reduced
Rud+
.
All further, low-lying bands disappear only at about 280 K,
supporting the assignment of these bands to CO molecules
binding strongly to more electron-rich, that is, reduced Rud+
sites due to enhanced p-backdonation (Figure S15 in the
Supporting Information). Our related theoretical studies on
CO binding to the parent 1 have shown[12b] that the local
2
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
organization of this “non-defective” framework is also not
straightforward. Rather, the simultaneous existence of two
different types of RuII/III paddle-wheels, one in which two Clꢀ
anions are coordinated at each of the two Ru sites and one in
which both Ru atoms are not coordinated, provided the best
match with the experiment. These reference data also make it
possible to rule out the interpretation of D1–D4 as a physical
mixture of 1 with various amounts of Ru nanoparticles (NPs),
because in such a case the intensity ratio of the (CO)Ru3+ and
(CO)Ru2+ species as well as their n(CO) frequencies would
not depend on the pydc concentration applied during syn-
thesis. Rather, D1–D4 reveal more than two nonequivalent
and accessible framework Ru sites different from that in
1 (even at low concentrations of pydc). Notably, related CO
adsorption studies monitored by UHV-FTIRS on [Cu3(btc)2]
thin-film (SURMOFs) materials showed about 4% of defec-
tive copper sites, which were identified as mixed-valence CuI/
CuII paddle-wheels.[8d] Hence, owing to the gradual decrease
in overall anionic charge upon increasing pydc doping, the
response of the framework in the reduction of Ru sites is quite
plausible.
Inspired by the above findings we expected unique
properties of the defect-engineered samples in comparison
to the parent 1. First, we studied low-temperature CO2
adsorption (UHV-FTIRS). Most surprisingly, after CO2
adsorption on D1–D3 two dominating, low-lying bands were
observed at 2039 and 2000 cmꢀ1 which are characteristic of
(CO)Rud+ species, and this unambiguously indicates CO2!
CO reduction. Importantly, for defect-free 1 only bands at
2335 and 2272 cmꢀ1 are observed, which are characteristic of
weakly physisorbed CO2, coordinated in linear fashion to Ru
sites. The intensity of these CO2-related bands gradually
decreases with increasing pydc doping in the series D1–D3,
while a significant enhancement of the low-lying bands
assigned to (CO)Rud+ is observed (Table 1, Figure 2). It
should be noted that dissociative chemisorption of CO2 in the
dark was not observed for Ru NPs.[15]
Photoinduced reduction of CO2 to CO and other valuable
organic molecules has been found on semiconducting nano-
materials (e.g. TiO2, CdS, ZnO) under irradiation with UV or
visible light.[16] Additionally, electrochemical reduction of
CO2 on various metallic electrodes has been reported.[17] For
MOFs, however, such a property is rather unprecedented and
very few exhibit activity towards CO2 conversion.[18] Namely,
for the CO2!CO photocatalytic reduction only UiO-67
functionalized with [ReI(dcbpy)(CO)3Cl] (dcbpy = 2,2’-bipyr-
idine-5,5’-dicarboxylic acid) was reported.[18a] A number of
RuII and RuI complexes are known to be efficient in the
photo- and electrocatalytic reduction of CO2 providing CO or
formic acid (or formates) as the products.[19] Since the reaction
on D1–D3 also takes place in the dark, we rule out the
photochemical pathway. Thus, considering that the defect-
free parent sample 1 is totally inactive (Figure 2, traces (b)),
the CO2!CO conversion at 90 K is likely to be driven by
strong interactions with reduced Rud+ CUS. Enhanced charge
transfer from Ru3d to the CO2 2pu antibonding orbital
dꢀ
possibly yields chemisorbed CO2 species that might act as
a reaction intermediate to finally produce CO. The activation
of CO2 could be further promoted by pydc due to the basic
pyridyl N sites in proximity to the reactive Ru sites (possible
formation of pyridyl NOx species).[20] In any case, during the
synthesis of D1–D3 and formation of reduced Rud+ centers,
energy is stored in the system to allow the removal of one O
atom from CO2. Unfortunately, we cannot comment on the
fate of this oxygen atom.
Ru complexes have a strong tendency to perform
a heterolytic, base-assisted activation of H2, instead of
oxidative addition, to generate Ru–hydride species
(Scheme 1).[21] Remarkably, D1–D4 form such Ru–H species
after H2 treatment as revealed by FTIR spectroscopy, while
the structural integrity is fully preserved (Scheme S1, Figures
S18–S22 in the Supporting Information). In fact, after the
samples had been heated under p(H2) new bands appear in
the characteristic region of Ru–H vibrations at 1956–1975 and
2057–2076 cmꢀ1.[22]
Figure 2. UHV-FTIR spectra (the regions of CO2 (A) and CO (B)
vibrations are displayed) obtained at 90 K after exposing the parent
1 (b) and defect-engineered D1 (c) and D3 (d) (representative
samples) to CO2 (1ꢃ10ꢀ4 mbar). Traces (a) represent spectra of
1 prior to the CO2 exposure. Temperature-dependent desorption experi-
ments are given in the Figures S16 and S17 in the Supporting
Information.
Scheme 1. Olefin hydrogenation involving base-assisted heterolytic
splitting of H2 over defect-engineered Ru-MOFs. Note that the pydc
linker in D1–D4 (Figure 1) offers a basic pyridyl-N atom in the
proximity of the reactive Ru centers.
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

.
Angewandte
Communications
This observation prompted us to screen the catalytic
properties of the samples and the influence of the defects on
the catalytic performance with and without hydrogen pre-
treatment. Indeed, there is huge variety of reactions, well-
known to be catalyzed by Ru: both homogeneous and
heterogeneous (like Ru/C or RuO2, etc.).[23] Nevertheless,
only few studies were reported on porous solids bearing Ru at
the framework nodes and, to the best of our knowledge, none
of them on Ru–CUS.[24] In view of the observed tendency of
our samples to form Ru–H species, we first investigated their
performance as olefin hydrogenation catalysts, using 1-octene
as the model compound. To track the influence of the
introduced defects, the samples D1 with low and D3 with high
pydc doping were selected. As can be seen in Figure 3, the
parent sample 1 displays only marginal hydrogenation
activity, producing only 12% conversion of 1-octene after
20 h. Introduction of pydc defects led to a clear increase in
line with the increased p-binding properties of the defect-
engineered materials. Interestingly, when the samples were
pretreated in situ at p(H2) = 8 atm and 423 K for 2 h before
the olefin was added at the reaction temperature, the catalytic
performance for olefin hydrogenation dramatically increased
(Figure 3), while olefin isomerization side reactions decreased
significantly.
FTIR spectroscopy showed that the enhanced activity and
selectivity for olefin hydrogenation versus the competing
isomerization side reaction is due to the efficient formation of
Ru–H species during pretreatment. Formation of Ru–H is
most likely the rate-determining step in a process such as that
depicted in Scheme 1. Notably, pydc could possibly assist this
heterolytic activation by acting as a suitable base ligand
(pyridyl-N site) in proximity to the reactive Ru sites. Indeed,
the rate of 1-octene hydrogenation increased with the
concentration of pydc, reflecting the extent of hydride species
formed during the pretreatment in each sample. Thus, the
time needed to attain full conversion of 1-octene was 3–4 h for
the parent 1, 2 h for D1, and less than 1 h for D3 (Figure 3,
insert). In all cases octane was the only product observed at
the end of the reaction. Similar hydrogenation results and
mechanistic interpretation were reported for RhII carboxylate
paddle-wheel MOFs.[25]
Similar to their activity in the hydrogenation of 1-octene,
D1–D3 display enhanced performance towards adsorption
and interaction with shorter unsaturated hydrocarbons (e.g.
ethylene; Figure S27 in the Supporting Information). They
served as catalysts with a progressive trend upon increasing
amount of pydc, for example in hydrogen-transfer reactions,
such as the Meerwein–Pondorf–Verley reduction of carbonyl
compounds and the isomerization of allylic alcohols to
saturated ketones. A more detailed evaluation of the catalytic
properties as a function of doping with defective linkers
(DLs) is underway and will be reported elsewhere. Let us just
mention here that the modified Ru–CUS of these materials
show multifunctional properties ranging from hydrogenation
to oxidation and Lewis acid catalysis.
In summary, we have demonstrated the controlled intro-
duction and the characterization of “defect” sites into an
isoreticular Ru analogue of HKUST-1. Incorporation of pydc
leads to partial reduction of the Ru sites at the defective
paddle-wheel moieties and triggers novel reactivity, which is
absent for the parent [Ru3(btc)2Cl1.5] (1). Thus, we anticipate
that other [M3(btc)2] compounds can be similarly modified.
The defective linkers (DLs) may be chosen with some
variation (Figures S28–S31) and pydc may be regarded as
just one representative example. Notably, the electronic
modification of CUS (i.e. more electron-rich sites) is accom-
panied by lowered coordination number, that is, with
expanded and functionalized coordination space in the
proximity of the modified metal site. This combination of
parameters which can be controlled by the choice of DLs
(even mixtures of such DLs; Figure S31 in the Supporting
Information) and framework incorporation level is likely to
yield libraries of a novel kind of multivariant MOFs suitable
for automated screening and property optimization.
Figure 3. Comparison of the 1-octene conversion over various pre-
treated samples (see text) represented as open symbols (without H2
pretreatment) and closed symbols (with H2 pretreatment): parent Ru-
&
MOF (1) (& and , respectively), and the defect-engineered variants
*
*
D3 ( and , respectively). Insert: Comparison of the 1-octene
~
conversion over H2-pretreated parent 1 with the samples D1 (( )) and
D3 with different pydc contents.
activity, and the conversion of 1-octene over sample D3 (ca.
30 mol% of pydc) was 50% after the same reaction time.
Meanwhile, along with the expected product, octane, a mix-
ture of intermediate products arising from isomerization side
reactions also formed, (E,Z)-2-octene, (E,Z)-3-octene, and
(E,Z)-4-octene, accounting for roughly 30% of the 1-octene
converted (Scheme S2 and Figure S26 in the Supporting
Information). This result reveals that some Ru–CUS present
in the samples have a certain p-acid character, in good
agreement with the observed behavior of parent sample
1 upon CO adsorption at 90 K, as monitored by UHV-FTIR
spectroscopy (Figure S14 in the Supporting Information).
As expected, the defect-engineered samples produced
slightly higher amounts of isomerization products than 1, in
4
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
Kauer, R. Schmid, B. Marler, M. Muhler, R. A. Fischer, Y. Wang,
J. Phys. Chem. C 2013, 117, 5658 – 5666.
[13] A. D. Burrows, CrystEngComm 2011, 13, 3623 – 3642.
[14] Y. Wang, A. Glenz, M. Muhler, C. Wçll, Rev. Sci. Instrum. 2009,
80, 113108.
Received: December 21, 2013
Published online: && &&, &&&&
Keywords: CO2 reduction · heterogeneous catalysis ·
.
hydrogen splitting · metal–organic frameworks ·
structural defects
[15] J. Raskꢃ, Catal. Lett. 1998, 56, 11 – 15.
[16] a) P. Usubharatana, D. McMartin, A. Veawab, P. Tontiwachwu-
thikul, Ind. Eng. Chem. Res. 2006, 45, 2558 – 2568; b) V. P.
Indrakanti, J. D. Kubicki, H. H. Schobert, Energy Environ. Sci.
2009, 2, 745 – 758; c) K. Mori, H. Yamashita, M. Anpo, RSC Adv.
2012, 2, 3165 – 3172.
[17] a) B. Kumar, M. Llorente, J. Froehlich, T. Dang, A. Sathrum,
C. P. Kubiak, Annu. Rev. Phys. Chem. 2012, 63, 541 – 569;
b) E. E. Benson, C. P. Kubiak, A. J. Sathrum, J. M. Smieja,
Chem. Soc. Rev. 2009, 38, 89 – 99.
[18] a) C. Wang, Z. Xie, K. E. de Krafft, W. Lin, J. Am. Chem. Soc.
2011, 133, 13445 – 13454; b) Y. Fu, D. Sun, Y. Chen, R. Huang, Z.
Ding, X. Fu, Z. Li, Angew. Chem. 2012, 124, 3420 – 3423; Angew.
Chem. Int. Ed. 2012, 51, 3364 – 3367.
[1] a) H. Furukawa, K. E. Cordova, M. OꢀKeeffe, O. M. Yaghi,
Science 2013, 341, 974 – 998; special issues: b) Chem. Soc. Rev.
2009, 38, 1213 – 1477; c) Chem. Soc. Rev. 2011, 40, 453 – 1152;
d) Chem. Rev. 2012, 112, 673 – 1268.
[2] a) A. Corma, H. Garcꢁa, F. X. Llabrꢂs i Xamena, Chem. Rev.
2010, 110, 4606 – 4655; b) T. Uemura, N. Uchida, M. Higuchi, S.
Kitagawa, Macromolecules 2011, 44, 2693 – 2697; c) Y.-Y. Fu, C.-
X. Yang, X.-P. Yan, Langmuir 2012, 28, 6794 – 6802.
[3] S. S. Y. Chui, S. M. F. Lo, J. P. H. Charmant, A. G. Orpen, I. D.
Williams, Science 1999, 283, 1148 – 1150.
[19] a) Y. Tsukahara, T. Wada, K. Tanaka, Chem. Lett. 2010, 39,
1134 – 1135; b) Z. Chen, C. Chen, D. R. Weinberg, P. Kang, J. J.
Concepcion, D. P. Harrison, M. S. Brookhart, T. J. Meyer, Chem.
Commun. 2011, 47, 12607 – 12609; c) N. Planas, T. Ono, L.
Vaquer, P. Mirꢃ, J. Benet-Buchholz, L. Gagliardi, C. J. Cramer,
A. Llobet, Phys. Chem. Chem. Phys. 2011, 13, 19480 – 19484.
[20] S. L. Jain, B. Sain, Chem. Commun. 2002, 1040 – 1041.
[21] a) H. D. Kaesz, R. B. Saillant, Chem. Rev. 1972, 72, 231 – 281;
b) D. Sellmann, R. Prakash, F. W. Heinemann, M. Moll, M.
Klimowicz, Angew. Chem. 2004, 116, 1913 – 1916; Angew. Chem.
Int. Ed. 2004, 43, 1877 – 1880.
[22] a) X. Wang, L. Andrews, J. Phys. Chem. A 2009, 113, 551 – 563;
b) C. P. Laua, S. M. Nga, G. Jia, Z. Lin, Coord. Chem. Rev. 2007,
251, 2223 – 2237.
[23] a) K. Yamaguchi, N. Mizuno, Angew. Chem. 2003, 115, 1518 –
1521; Angew. Chem. Int. Ed. 2003, 42, 1480 – 1483; b) F. Su, F. Y.
Lee, L. Lv, J. Liu, X. N. Tian, X. S. Zhao, Adv. Funct. Mater. 2007,
17, 1926 – 1931; c) H. Over, Chem. Rev. 2012, 112, 3356 – 3342;
d) H. Miura, K. Wada, S. Hosokawa, M. Sai, T. Kondo, M. Inoue,
Chem. Commun. 2009, 4112 – 4114.
[4] M. Kramer, U. Schwarz, S. Kaskel, J. Mater. Chem. 2006, 16,
2245 – 2248.
[5] L. J. Murray, M. Dinca, J. Yano, S. Chavan, S. Bordiga, C. M.
Brown, J. R. Long, J. Am. Chem. Soc. 2010, 132, 7856 – 7857.
[6] P. Maniam, N. Stock, Inorg. Chem. 2011, 50, 5085 – 5097.
[7] J. I. Feldblyum, M. Liu, D. W. Gidley, A. J. Matzger, J. Am.
Chem. Soc. 2011, 133, 18257 – 18263.
[8] a) L. Huang, H. Wang, J. Chen, Z. Wang, J. Sun, D. Zhao, Y. Yan,
Microporous Mesoporous Mater. 2003, 58, 105 – 114; b) S. Marx,
W. Kleist, A. Baiker, J. Catal. 2011, 281, 76 – 87; c) T.-H. Park,
A. J. Hickman, K. Koh, S. Martin, A. G. Wong-Foy, M. S.
Sanford, A. J. Matzger, J. Am. Chem. Soc. 2011, 133, 20138 –
20141; d) P. St. Petkov, G. N. Vayssilov, J. Liu, O. Shekhah, Y.
Wang, C. Wçll, T. Heine, ChemPhysChem 2012, 13, 2025 – 2029.
[9] a) C. Chizallet, S. Lazare, D. Bazer-Bachi, F. Bonnier, V. Lecocq,
E. Soyer, A. Quoineaud, N. Bats, J. Am. Chem. Soc. 2010, 132,
12365 – 12377; b) F. X. Llabrꢂs i Xamena, F. G. Cirujano, A.
Corma, Microporous Mesoporous Mater. 2012, 157, 112 – 117.
[10] U. Ravon, M. Savonnet, S. Aguado, M. E. Domine, E. Janneau,
D. Farrusseng, Microporous Mesoporous Mater. 2010, 129, 319 –
329.
[11] F. Vermoortele, B. Bueken, G. Le Bars, B. Van de Voorde, M.
Vandichel, K. Houthoofd, A. Vimont, M. Daturi, M. Waroquier,
V. Van Speybroeck, C. Kirschhock, D. E. De Vos, J. Am. Chem.
Soc. 2013, 135, 11465 – 11468.
[12] a) O. Kozachuk, K. Yusenko, H. Noei, Y. Wang, S. Walleck, T.
Glaser, R. A. Fischer, Chem. Commun. 2011, 47, 8509 – 8511;
b) H. Noei, O. Kozachuk, S. Amirjalayer, S. Bureekaew, M.
[24] a) R. Tannenbaum, Chem. Mater. 1994, 6, 550 – 555; b) R.
Tannenbaum, J. Mol. Catal. A 1996, 107, 207 – 215.
[25] a) T. Sato, W. Mori, C. N. Kato, T. Ohmura, T. Sato, K.
Yokoyama, S. Takamizawa, S. Naito, Chem. Lett. 2003, 32,
854 – 855; b) T. Sato, W. Mori, C. N. Kato, E. Yanaoka, T.
Kuribayashi, R. Ohtera, Y. Shiraishi, J. Catal. 2005, 232, 186 –
198.
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

.
Angewandte
Communications
Communications
Metal–Organic Frameworks
The defect engineering in Ru-based
metal–organic frameworks (MOFs) at
coordinatively unsaturated metal centers
(CUS) induces partial reduction of the
metal nodes and leads to properties that
are absent for the parent MOF, such as
dissociative chemisorption of CO2 and
enhanced sorption capacity of CO. The
modified MOFs offer new perspectives as
multifunctional materials whose perfor-
mance is controlled by design of the
defects.
O. Kozachuk, I. Luz,
F. X. Llabrꢁs i Xamena, H. Noei,
M. Kauer, H. B. Albada, E. D. Bloch,
B. Marler, Y. Wang,* M. Muhler,
R. A. Fischer*
&&&& — &&&&
Multifunctional, Defect-Engineered
Metal–Organic Frameworks with
Ruthenium Centers: Sorption and
Catalytic Properties
6
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
These are not the final page numbers!