Encapsulation of Crabtree's Catalyst in Sulfonated MIL-101(Cr): Enhancement of Stability and Selectivity between Competing Reaction Pathways by the MOF Chemical Microenvironment

Article abstract of DOI:10.1002/anie.201710091

Crabtree's catalyst was encapsulated inside the pores of the sulfonated MIL-101(Cr) metal–organic framework (MOF) by cation exchange. This hybrid catalyst is active for the heterogeneous hydrogenation of non-functionalized alkenes either in solution or in the gas phase. Moreover, encapsulation inside a well-defined hydrophilic microenvironment enhances catalyst stability and selectivity to hydrogenation over isomerization for substrates bearing ligating functionalities. Accordingly, the encapsulated catalyst significantly outperforms its homogeneous counterpart in the hydrogenation of olefinic alcohols in terms of overall conversion and selectivity, with the chemical microenvironment of the MOF host favouring one out of two competing reaction pathways.

Full text of DOI:10.1002/anie.201710091

A Journal of the Gesellschaft Deutscher Chemiker
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Accepted Article
Title: Encapsulation of Crabtree's catalyst in sulfonated MIL-101(Cr):
enhancement of stability and selectivity between competing
reaction pathways by the MOF chemical microenvironment
Authors: Matthew J. Rosseinsky, Alexios Grigoropoulos, Alasdair I.
McKay, Alexandros P. Katsoulidis, Robert P. Davies, Anthony
Haynes, Lee Brammer, Jianliang Xiao, and Andrew S. Weller
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201710091
Angew. Chem. 10.1002/ange.201710091
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Encapsulation of Crabtree’s catalyst in sulfonated MIL-101(Cr):
enhancement of stability and selectivity between competing
reaction pathways by the MOF chemical microenvironment
Alexios Grigoropoulos,[a] Alasdair I. McKay,[b] Alexandros P. Katsoulidis,[a] Robert P. Davies,[c] Anthony
Haynes,[d] Lee Brammer,[d] Jianliang Xiao,[a] Andrew S. Weller[b]* and Matthew J. Rosseinsky[a]*
In memory of Professor Gérard Férey
Abstract: Crabtree’s catalyst was encapsulated inside the pores of
the sulfonated MIL-101(Cr) metal-organic framework (MOF) by cation
exchange. This hybrid catalyst is active for the heterogeneous
hydrogenation of non-functionalized alkenes either in solution or in the
gas phase. Moreover, encapsulation inside a well-defined hydrophilic
microenvironment enhances catalyst stability and selectivity to
hydrogenation over isomerization for substrates bearing ligating
functionalities. Accordingly, the encapsulated catalyst significantly
outperforms its homogeneous counterpart in the hydrogenation of
olefinic alcohols in terms of overall conversion and selectivity with the
chemical microenvironment of the MOF host favouring one out of two
competing reaction pathways.
self-association reaction can be attenuated via modification of the
coordination sphere of Ir[11] or employment of larger weakly
coordinating anions.[12] Substrates bearing ligating functionalities
such as olefinic alcohols show a more complicated behavior with
Crabtree’s catalyst since isomerization[13] can also take place in
parallel with hydrogenation.[14]
Metal-organic frameworks (MOFs)[1] are crystalline and
permanently porous materials which have emerged as promising
hosts for the immobilization of organometallic catalysts,[2] since
they allow for control of the steric and chemical microenvironment
around the encapsulated catalytically active species. This in turn
could promote catalytic activity and selectivity through extended
coordination sphere interactions. These concepts lie behind the
exceptional reactivity and selectivity of metalloenzymes,[3]
however their transfer to the design and synthesis of artificial
catalysts is challenging.[4] Several examples of MOF-supported
catalysts showing exceptional overall catalytic activity have been
reported.[5]-[6] Enhancement of selectivity between products of a
single reaction pathway by control of the steric[7] or the chemical[8]
microenvironment has also been demonstrated.
Scheme 1. Encapsulation of the cationic component of Crabtree’s catalyst (2,
blue sphere) in sulfonated MIL-101(Cr) (1-SO3Na, cube) by exchange of the
charge-balancing Na+ cations (red sphere).
Here we use the Na+ salt of sulfonated MIL-101(Cr) MOF (1-
SO3Na) as the anionic framework host for encapsulation of the
cationic component of Crabtree’s catalyst [Ir(cod)(PCy3)(py)][PF6]
(2-PF6) by cation exchange,[15] forming 2@1-SO3Na (Scheme 1).
Encapsulation of cation 2 inside a well-defined, anionic and
hydrophilic microenvironment forms an efficient heterogeneous
catalyst for the hydrogenation of non-functionalized alkenes in
solution, enables hydrogenation in the gas phase and most
importantly enhances the catalyst’s activity and selectivity for the
hydrogenation of olefinic alcohols by suppressing the competing
isomerization reaction. The MOF chemical microenvironment
directs substrates along one of two distinct reaction pathways.
The sulfonated analogue of MIL-101(Cr) (1-SO3H)[16] is a
robust, readily synthesized anionic MOF. It is isostructural with
pristine MIL-101(Cr)[17] with two charge-balancing cations per
formula unit, [HxNa2-x][Cr3(µ3-O)(BDC-SO3)3] (x = 1.8 ± 0.1, Figure
S1, H2BDC-SO3Na = 2-sulfoterephthalic acid sodium salt). Each
cubic unit cell (a = 87.63(3) Å) contains 8 bigger and 16 smaller
mesopores, large enough to accommodate 2 (Figures S2, S3). It
has been reported that the cations within 1-SO3H can be partially
Crabtree’s catalyst is one of the best commercially available
homogeneous catalysts for hydrogenation of alkenes.[9] However,
it is deactivated in solution under hydrogenation conditions,
forming catalytically inactive polymetallic hydride clusters.[10] This
[a] Dr A. Grigoropoulos, Dr A. P. Katsoulidis,
Prof. J. Xiao, Prof. M. J. Rosseinsky
Department of Chemistry, University of Liverpool
Liverpool L69 7ZD, UK
E-mail: M.J.Rosseinsky@liverpool.ac.uk
[b] Dr A. I. McKay, Prof. A. S. Weller
Department of Chemistry, University of Oxford
Chemistry Research Laboratories, Oxford OX1 3TA, U.K
E-mail: andrew.weller@chem.ox.ac.uk
[c] Dr R. P. Davies
Department of Chemistry, Imperial College London
South Kensington, London SW7 2AZ, U.K.
[d] Dr A. Haynes, Prof. L. Brammer
Department of Chemistry, University of Sheffield
Brook Hill, Sheffield S3 7HF, U.K.
exchanged with Ag+[18] or [Rh(cod)(dppe)]+ [dppe
bis(diphenylphosphino)ethane].[19]
= 1,2-
Supporting information and the ORCID identification number(s) for
the author(s) of this article can be found in https://
1
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10.1002/anie.201710091
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Figure 1. a) Comparison of PXRD patterns and unit cell parameter (퐹푑3푚 space group) for 2@1-SO3Na (magenta), 1-SO3Na (red), 1-SO3H (green) and MIL-
101(Cr) (calculated, black).[17] Le Bail fits are included in the supporting information. b) N2 uptake of the desolvated materials at 77 K (BET = surface area, VP
= pore volume). c) 31P{1H} MAS NMR spectrum of 2-PF6 (black) and 2@1-SO3Na (red). Spinning side bands are marked with an asterisk.
In order to increase the number of exchangeable Na+ cations,
1-SO3H was treated with AcONa/AcOH buffer solution (pH = 4.7),
forming [HyNa2-y][Cr3(µ3-O)(BDC-SO3)3] (1-SO3Na, y = 0.2 ± 0.1,
Table S1). 1-SO3Na remains crystalline and mesoporous (Figures
1a, 1b) with only a small change in the cubic unit cell parameter
(a = 87.99(4) Å) and a slight increase in the measured porosity
(BET surface area = 2005 m2 g-1, VP = 0.91 cm3 g-1) and the pore
size distribution, compared to 1-SO3H (Figure S9).
After establishing an appropriate cation exchange protocol
using [Cp*2Co]+ as a cationic probe (Table S2 and Figures S6,
S9-S12), as we have shown previously,[15b] 2-PF6 was used as a
cationic guest precursor. Since water can poison the catalytically
active species,[12] cation exchange was carried out using
desolvated 1-SO3Na as the anionic host in dry and degassed
acetone, producing 2@1-SO3Na. Crystallinity was retained after
cation exchange with only a minor change in the cubic unit cell
parameter (a = 87.74(3) Å, Figure 1a, see Le Bail fit in Figure S7),
whereas BET surface area (1570 m2 g-1) and pore volume (0.70
cm3 g-1) were reduced, compared to 1-SO3Na (Figure 1b).
To explore the possible interaction of the sulfonate groups
decorating the pore walls of 1-SO3Na with the Ir center of 2 after
encapsulation, the tosylate anion [OTs]– was selected to model
the BDC-SO3 linkers. Two new complexes were synthesized,
[Ir(cod)(PCy3)(py)][OTs] (2-OTs) and [Ir(cod)(PCy3)(OTs)] (3), in
which OTs acts as a counter anion or as a ligand to Ir, respectively
(Figures 2a, 2b, Figures S16, S17, Table S4). 31P{1H} and 1H
EXSY NMR spectroscopy in CD2Cl2 (Figures S18-S20) revealed
that a dynamic reversible ligand exchange takes place between
complexes 2-OTs and 3, with OTs replacing pyridine in the
coordination sphere of Ir (Figure 2c). This suggests that the
sulfonate groups in 2@1-SO3Na may also play a non-spectator
role, with potential implications in catalysis, as discussed next.
ICP-OES after digestion of 2@1-SO3Na gave an Ir content of
2.28 wt %, indicating that 7% of the Na+ cations have been
exchanged with 2 (Table S3). ICP-OES also showed an equimolar
Ir/P ratio, and only one broad peak was observed (δP = 15.65,
fwhm ~ 15 ppm) in the 31P{1H} MAS NMR spectrum of 2@1-
SO3Na, assigned to the PCy3 ligand (Figure 1c). Signals arising
from the [PF6]– anion were not observed either in the 31P{1H} MAS
or the 19F{1H} solution NMR spectra of 2@1-SO3Na after digestion,
in contrast with the respective spectra of 2-PF6 (Figure S13). The
1H solution NMR spectrum of 2@1-SO3Na after digestion showed
three low intensity peaks at 8.22, 7.58 and 7.16 ppm, assigned to
pyridine (Figure S14). Treatment of 2@1-SO3Na with D2 gas
resulted in deuteration of the cod ligand and formation of d4-
Figure 2. a) Single crystal structure of 2-OTs ([OTs]– counter anion is not
shown for clarity). b) Single crystal structure of 3 (OTs coordinated cis to
PCy3). c) Reversible ligand exchange between 2-OTs and 3 in CD2Cl2.
2
cyclooctane, as detected by H MAS NMR spectroscopy (Figure
The catalytic performance of 2@1-SO3Na was benchmarked
against 2-PF6 in the hydrogenation of non-functionalized alkenes
in CH2Cl2 under mild conditions (Table 1). Control experiments
verified that 1-SO3Na does not catalyze the hydrogenation of oct-
1-ene (4). Introduction of 2@1-SO3Na as the catalyst afforded
complete hydrogenation of 4 to n-octane, at loadings as low as 50
ppm (entries 1-3). When the loading was reduced to 10 ppm
(entry 4), selective conversion of 4 to n-octane reached 83%
S15). These analytical and spectroscopic data are consistent with
cation 2 being encapsulated intact inside the mesopores of 1-
SO3Na by a simple cation exchange process. The down-field
chemical shift and peak broadening observed for the signal due
to the PCy3 ligand in the 31P{1H} MAS NMR spectrum of 2@1-
SO3Na, compared to 2-PF6, likely originate from the different
anionic environment surrounding 2.[20]
2
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(TON = 8.3 x 104). Homogeneous catalyst 2-PF6 under identical
conditions produced comparable results, demonstrating that
encapsulation is not detrimental to catalytic activity.
increase compared to the non-porous solid 2-PF6 (Figure 3).
Recycling of 2@1-SO3Na was also successful upon exposure to
fresh but-1-ene (Figure S23).
Table 1. Hydrogenation of non-functionalized alkenes with heterogeneous
2@1-SO3Na and homogeneous 2-PF6 catalysts.[a]
Entry
Substrate
Loading Time
2@1-SO3Na
2-PF6
(ppm)
1000[c]
100[d]
50[e]
(h) Conv[b] TON
Conv[b] TON
1
2
3
4
5
6
7
8
9
3
>99%
>990
100%
1000
20
24
24
3
100% 10000 100% 10000
100% 20000
—
94%
100%
—
—
94000
1000
—
4
10[f]
83%
>99%
100%
10%
83000
>990
1000
100
Figure 3. Gas/solid hydrogenation of but-1-ene over 2@1-SO3Na (red) and
2-PF6 (blue). Conditions: T = 20 °C, PH2 < 4 bar, 0.5 mg of solid catalyst used.
1000[c]
1000[c]
5
6
20
3
The mesopores of 2@1-SO3Na are hydrophilic due to the
presence of H-bond accepting sulfonate groups as well as Lewis
acidic Cr(III) sites and Na+ cations. Therefore, the reactivity of
Crabtree’s catalyst with substrates bearing functional groups
which can interact with such an environment could significantly
change due to encapsulation. We chose to explore this by using
olefinic alcohols as substrates, whose fundamental characteristic
is the competition between hydrogenation and isomerization upon
turnover.[22] Hydrogenation of a series of olefinic alcohols was
carried out under a ~20-fold excess of H2 (Table 2).
12%
37%
120
20
26%
260
370
3
69%
81%
690
810
100%
1000
1000[c]
10
20
—
—
7
[a] CH2Cl2 solvent, T = 20 °C; [b] conversion (%) based on GC; [c] [alkene]
= 0.5 M, V = 1 mL, 8 mmol of H2; [d] [alkene] = 1.0 M, V = 4 mL, 16 mmol
of H2; [e] [alkene] = 1.0 M, V = 10 mL, 48 mmol of H2; [f] [alkene] = 1.5 M,
V = 12 mL, 48 mmol of H2.
Complete hydrogenation of pent-4-en-1-ol (8a), pent-4-en-2-
ol (9a) and 2-methylbut-3-en-1-ol (10a) to the respective alcohols
8b-10b was observed with 2-PF6 in 3 h. Isomerization products
were not detected (Figure S24), as reported for 2-PF6 using
similar substrates.[23] Complete hydrogenation of 8a-10a to 8b-
10b was also achieved with 2@1-SO3Na, albeit in 24 h (entries 1-
6). Isomerization products were again not detected. Conversion
in 3 h correlates well with the steric hindrance around the double
bond of the substrate: 10% for 10a (more hindered), increasing to
22% for 9a (less hindered) and reaching 34% for 8a (linear).
Olefinic alcohols 8a-10a were hydrogenated considerably slower
with 2@1-SO3Na, compared to the sterically comparable non-
functionalized alkenes 4 and 5 (Table 1). This is consistent with a
strong interaction between the hydroxyl group of the olefinic
alcohols and the chemical microenvironment of 2@1-SO3Na.
Substrates which are intrinsically more susceptible to
isomerization, such as the homoallylic 11a and allylic 12a-13a
alcohols,[23-24] revealed a significant enhancement of reactivity
and selectivity to hydrogenation with 2@1-SO3Na, compared to
its homogeneous counterpart. 2-PF6 afforded 56% conversion of
11a in 3 h and 57% in 24 h, indicative of catalyst deactivation
(entries 7-8, Figure S25). Moreover, isomerization of 11a was also
observed, producing a non-negligible amount of the internal
olefinic alcohol 11c and traces of the aldehyde 11d. As a result,
selectivity to hydrogenation and formation of n-butanol (11b) was
only 85% for the homogeneous system.
The branched, but unhindered, aliphatic alkene, 3-methylhex-
1-ene (5) was also completely hydrogenated using 2@1-SO3Na
at 1000 ppm loading (entries 5-6). The hindered aliphatic alkene,
2-methylhex-1-ene (6) was only partially hydrogenated with either
catalyst after 20 h (entries 7-8). Conversion did not increase any
further after 72 h in either system, reflecting catalyst deactivation.
When cyclohexene (7) was employed as a substrate, conversion
reached 69% in 3 h with 2@1-SO3Na as the catalyst but increased
only to 81% after 20 h. On the contrary, 100% conversion was
observed with 2-PF6 in 3 h (entries 9-10).
The different response observed for this bulkier substrate is
consistent with hydrogenation taking place within the pores and
not on the surface of 2@1-SO3Na. The heterogeneity of the
reaction was further established by carrying out a leaching test
(Figure S21). Recycling of 2@1-SO3Na was also possible with a
small decrease in activity (82% conversion) during the third cycle
(Figure S22).
2@1-SO3Na is a versatile catalyst which can also be
employed in a gas/solid reaction,[21] as demonstrated by the
complete hydrogenation of but-1-ene over 2@1-SO3Na in 2.5 h
(4000 µmol of but-1-ene hydrogenated per 1 mg of Ir). Although
finely ground solid 2-PF6 was also active, dispersion of 2 in the
porous anionic solid-state support increases the number of
accessible catalytic sites in 2@1-SO3Na, resulting in a 6-fold
3
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and 13d was significantly suppressed, resulting in
≥90% selectivity for the alcohols 12b and 13b.
To probe the effect of the sulfonate group on
stability and selectivity, we also investigated the
homogeneous hydrogenation of crotyl alcohol using
2-OTs and 3 as catalysts (Figure S30). Higher
conversions were observed compared to 2-PF6 (77%
for 2-OTs and 83% for 3 in 24 h) in accordance with
OTs being a more strongly coordinating anion, hence
prolonging the catalyst’s lifetime.[25] By contrast,
selectivity to hydrogenation did not significantly
improve (39% for 2-OTs and 53% for 3), remaining
considerably lower than that of 2@1-SO3Na (82%).
The reaction pathways for the hydrogenation or
isomerization of olefinic alcohols with the
homogeneous catalyst 2-PF6 likely share the same
starting point, the formation of a cationic Ir(III)-
dihydride complex in which the hydroxyl group is also
coordinated to Ir (Scheme 2, intermediate I), followed
by migratory insertion (intermediate II).[13-14]
Bifurcation into separate, competitive pathways then
occurs: (i) hydrogenation to the respective alcohol via
reductive elimination (pathway A) or (ii) isomerization
to the internal olefin via β-elimination, which requires
an appropriately orientated vacant coordination site,
followed by off-cycle tautomerization to the aldehyde
(pathway B).
Table 2. Substrate conversion[a] and product selectivity[a, b] for hydrogenation of olefinic
alcohols with heterogeneous 2@1-SO3Na and homogeneous 2-PF6 catalysts.[c]
Entry Substrate
Time
(h)
3
2@1-SO3Na
2-PF6
Conv
34
b
c
d
Conv
100
—
b
c
d
n.d.
—
1
100 n.d.[d] n.d.
100
—
n.d.
—
8a
2
24
3
100
22
100
100
100
100
100
95
n.d.
n.d.
n.d.
n.d.
n.d.
5
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
7
3
100
—
100
—
n.d.
—
n.d.
—
4
24
3
100
10
9a
5
100
—
100
—
n.d.
—
n.d.
—
10a
6
24
3
100
33
7
56
85
13
2
11a
8
24
3
100
41
100
93
n.d.
n.d.
n.d.
n.d.
n.d.
57
83
13
4
9
69[e]
62[e]
54[e]
53[e]
61
n.d.
n.d.
n.d.
n.d.
35
19
54
26
12a
10
24
3
96
92
8
55
11
26
92
8
31
The significantly improved selectivity to
hydrogenation observed with 2@1-SO3Na suggests
that isomerization is suppressed. We propose that
this could take place due to extended coordination
sphere interactions between the hydroxyl group of the
olefinic alcohols and the chemical microenvironment
around 2, such as H-bonding to the sulfonate groups.
13a
12
24
82
90
10
28
[a] based on 1H NMR using mesitylene as standard for verifying mass-balance; [b] yield of
each product over total conversion; [c] 0.1 mol % loading, [substrate] = 0.5 M in CH2Cl2, V =
0.7 mL, ~8 mmol of H2; [d] not detected; [e] formation of ill-defined condensation products
was also observed, especially after 24 h.
By contrast, the heterogeneous catalyst 2@1-SO3Na afforded
complete conversion and 100% selectivity to hydrogenation and
formation of 11b (entries 7-8, Figure S26). Monitoring conversion
for both systems over time (Figure S27) verified that 2-PF6 is
deactivated after 3 h, whereas 2@1-SO3Na remained productive,
affording full conversion in 6 h. Although traces of the internal
olefin 11c were detected in short reaction times, 11c was
subsequently also hydrogenated to 11b. The encapsulated
catalyst is thus more stable, more active with respect to overall
conversion and more selective.
The superior performance of 2@1-SO3Na was even more
pronounced in the hydrogenation of allylic alcohols which can
isomerize directly to the respective aldehydes. Conversion under
hydrogenation conditions for trans-pent-2-en-1-ol (12a, entries 9-
10) and trans-crotyl alcohol (13a, entries 11-12) in 3 h with 2-PF6
was 69% and 54%, respectively (Figure S28). Conversion did not
increase after 24 h, indicating catalyst deactivation. Selectivity to
hydrogenation was poor: 61% for alcohol 12b in 3 h with a
substantial amount of the aldehyde 12d formed (35% selectivity)
and 31% for alcohol 13b in 3 h with the aldehyde 13d now being
the main product (54% selectivity). By contrast, overall conversion
with 2@1-SO3Na as the catalyst reached 96% for 12a and 82%
for 13a in 24 h (Figure S29). Isomerization to the aldehydes 12d
Scheme 2. a) Competing pathways for hydrogenation (A) and isomerization (B)
of olefinic alcohols with 2-PF6. b) Proposed pathway (C) for hydrogenation and
suppression of isomerization with 2@1-SO3Na.
This disfavors coordination of the hydroxyl group to Ir and
enables formation of the dihydrogen complex III, in preference to
I (pathway C). Productive hydrogenation occurs via an octahedral
4
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7440-7444; b) L. Mitchell, P. Williamson, B. Ehrlichová, A. E. Anderson, V.
R. Seymour, S. E. Ashbrook, N. Acerbi, L. M. Daniels, R. I. Walton, M. L.
Clarke, P. A. Wright, Chem. Eur. J. 2014, 20, 17185-17197; c) K. Manna,
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2194; e) Z. Li, J.-D. Xiao, H.-L. Jiang, ACS Catal. 2016, 6, 5359-5365; f) A.
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Ir(V)-trihydride species (IV), as proposed for non-functionalized
[26]
alkenes with Crabtree-type catalysts
and β-elimination is
suppressed since Ir is coordinatively saturated throughout.
2@1-SO3Na also resulted in higher overall conversions for the
hydrogenation of olefinic alcohols, compared to 2-PF6. A series of
selective poisoning experiments revealed that the isomerization
products are not responsible for catalyst deactivation (Table S7).
We thus suggest that 2@1-SO3Na has a longer lifetime due to: (i)
spatial isolation of the positively charged catalytically active
species inside the pores of the anionic MOF which hinders the
formation of catalytically inactive clusters and/or (ii) reversible
coordination of the sulfonate anion, as shown with 2-OTs and 3.
In summary, we demonstrate that the hybrid catalyst 2@1-
SO3Na is capable of hydrogenating non-functionalized alkenes at
low loadings in solution and in the gas phase under mild
conditions. It outperforms its homogeneous counterpart in the
hydrogenation of olefinic alcohols, showing significantly higher
conversions under otherwise identical conditions. In addition,
encapsulation results in a pronounced selectivity enhancement in
favor of hydrogenation by suppressing the competing
isomerization reaction due to extended coordination sphere
interactions of the catalytic center with the chemically
functionalized internal surface of the MOF. Capitalizing on such
stability and selectivity enhancements is likely to be important in
deploying such hybrid systems in catalytic applications under
continuous flow.[27]In metalloenzymes, it is well-established that
well-positioned amino acid residues around the active site control
its reactivity and selectivity.[3] Here, the well-defined, readily
engineered MOF chemical microenvironment controls reactivity
and selectivity of the encapsulated catalyst, allowing for
discrimination between distinct reaction pathways.
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Acknowledgements
UK Catalysis Hub Consortium is kindly thanked for support and
resources (EPSRC grants EP/K014706/1, EP/K014668/1,
EP/K014854/1, EP/K014714/1 and EP/M013219/1).
Keywords: Crabtree’s catalyst • encapsulation • hydrogenation •
metal organic framework • allylic alcohol
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5
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[27] U. Hintermair, G. Francio, W. Leitner, Chem. Comm. 2011, 47, 3691-3701.
6
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10.1002/anie.201710091
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Entry for the Table of Contents (Please choose one layout)
Layout 1:
COMMUNICATION
Encapsulation
of
Crabtree’s
Dr A. Grigoropoulos, Dr A. I. McKay,
Dr A. P. Katsoulidis, Dr R. P. Davies,
Dr A. Haynes, Prof. L. Brammer,
Prof. J. Xiao, Prof. A. S. Weller* and
Prof. M. J. Rosseinsky*
catalyst inside the sulfonated
analogue of MIL-101(Cr) by cation
exchange significantly increases
activity
hydrogenation of olefinic alcohols
with the MOF chemical
and
selectivity
to
microenvironment directing the
substrate along one out of two
competing reaction pathways.
Encapsulation of Crabtree’s
catalyst in sulfonated MIL-101(Cr):
enhancement of stability and
selectivity between competing
reaction pathways by the MOF
chemical microenvironment
Layout 2:
COMMUNICATION
Author(s), Corresponding Author(s)*
((Insert TOC Graphic here))
Page No. – Page No.
Title
Text for Table of Contents
7
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