This is the peer reviewed version of the following article: Chem. Eur.J. 2016, 22, 13582 –13587, which has been
published in final form at http://onlinelibrary.wiley.com/doi/10.1002/chem.201600898/abstract. This article may be
used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."

Modulation by amino acids: towards superior control in Zr-MOFs
synthesis
Oleksii V. Gutov,a* Sonia Molinaa, Eduardo C. Escudero-Adán,a Alexandr Shafir*a
Abstract: Zr-MOF synthesis modulated by various amino acids,
including L-proline, glycine and L-phenylalanine is shown as a
straightforward approach towards functional group incorporation and
particle size control. High yields in Zr-MOF are achieved employing
5 equiv of the modulator at 120 oC; at lower temperatures, the
method provides a series of Zr-MOFs with increased particle size,
including many suitable for single crystal X-Ray diffraction.
Furthermore, amino acid modulators can be incorporated at defect
sites of Zr-MOFs with up to 1:1 amino acid-to-strut ratio, depending
on the ligand structure and reaction conditions. The MOFs obtained
through amino acid modulation exhibit improved CO2 capture
capacity when compared to non-functionalized material.

Introduction
The Metal-Organic Frameworks (MOFs) assembled from the
Zr6-oxo cluster nodes and a polytopic carboxylate linker,
pioneered by Lillerud et al.,1 have emerged as promising porous
materials for applications ranging from gas storage and
separations to catalysis and sensing. In addition to the chemical
versatility offered by the organic linker, these Zr-based MOFs
show a remarkable stability, partly attributed to the high degree
of connectivity, up to 12 carboxylates/cluster, associated with
the Zr6 node.1,2 Interestingly, the synthesis of such materials,
exemplified by the UiO-family1 of MOFs, is commonly
accomplished in the presence of a modulating agent, often a
mono-carboxylic acid, e.g. benzoic or formic acids.3 It is likely
that the modulator, used in excess, leads to a more controlled
network growth through the initial formation of soluble
monomeric Zr6(OH)4(O)4(RCOO)12 clusters which then assemble
through a slower dynamic exchange between the modulator and
the linker units (Scheme 1). Indeed, assembly of discrete
isolated Zr6 carboxylate clusters has been established as a valid
route towards UiO-type MOFs.4

MOF.

Thus, modulation is now commonly used to induce higher levels
of crystallinity and larger particle size often desired in several
applications, including the possibility of a high-yield generation3
of MOF particles of >1 μm size desirable in chromatography and
continuous flow chemistry. Acid modulation has also been the
key to achieve single crystals of Zr-MOF suitable for X-Ray
analysis, aiding in the rational design of new materials and their
detailed structural characterization.3,5 Despite these advances,
the generation of X-Ray quality single crystals in Zr-MOFs
remains largely a trial-and-error enterprise. Interestingly, acid
modulation in Zr-MOF synthesis has been recently shown to
play a key role in the nature and quantity of defects present in
the Zr MOF network. These defects, in turn, have come under
an intense spotlight as potential sites for MOF
functionalization,3b,6 complementing the covalent linker
modification approach.7
During the course of our own work on defect control and
chemical modification in the UiO-family of MOFs, we reported
that L-Proline (L-Pro) could be incorporated at missing linker
formate-capped defects sites by treating samples of UiO-67
(Scheme 2A) with L-Proline hydrochloride.3b,8 This led us to
ponder the possibility of achieving Zr-MOFs containing L-Pro (or
other amino acids) directly through modulation with the
corresponding amino acid (Scheme 2B). Independently, since
2015, the Forgan laboratory has exploited the excellent
modulating abilities of L-Pro and studied the phenomenon of
amino acid modulation.9 It should also be mentioned that
applications of L-Proline in MOF design include the induction of
supramolecular chirality in Zn-based MOF-5 crystals.10

Scheme 2. A) Anchoring of L-Pro onto Zr-MOF (ref. 3b); B) amino-acid
modulated MOF synthesis.
Scheme 1. The modulation phenomenon illustrated for the formation of UiO-66

[a]

Dr. O.V. Gutov, S. Molina, Dr. E.C. Escudero-Adán, Dr. A. Shafir
Institute of Chemical Research of Catalonia (ICIQ), Barcelona
Institute of Science and Technology, Avda. Països Catalans 16,
43007, Tarragona, Spain
E-mail: ashafir@iciq.es; avgutov@gmail.com.
Supporting information for this article is given via a link at the end of
the document.

Here, we wish to report our full study on the amino acid effect in
the growth of Zr-MOF, including the exceptional modulating
ability of L-Proline. Through a series of optimization experiments,
two protocols have been identified for the use of L-Proline·HCl
modulator in an exceptionally efficient generation of X-Ray
quality single crystals. In addition, it was also found that amino
acids can be incorporated at Zr MOF defects sites opening the
door to new functional materials.

Results and Discussion
For the modulated synthesis of metal-organic framework, the
solubility of the modulator acid in the reaction medium is likely a
key factor for efficient growth of the 3D network. For several
amino acids, including L-proline, the free base form proved
largely insoluble in DMF, and showed poor modulating ability in
the preparation of Zr-MOFs. Experimentally, converting the
amino acids into the corresponding hydrochlorides proved
crucial to ensure their solubility in DMF, enabling their use as
modulators in the syntheses of Zr-MOF. Initial tests were
conducted by exploring the growth of the isoreticular UiO-66 and
UiO-67 pair in the presence of glycine (Gly), L-proline (L-Pro)
and L-phenylalanine (L-Phe). Thus, in a sealable vial a mixture
of ZrOCl2·8H2O and the aminoacid (5 equiv with respect to the
linker) was dissolved in a mixture of DMF and HClaq; the linker
diacid (p-terephthalic or biphenyl dicarboxylic) was then added
and the vial was stored at 120 oC. Both UiO-66 or UiO-67 were
readily obtained under these conditions (as per powder X-Ray
diffraction, pXRD) with particle sizes <1 μm for L-Phe, and >1
μm for Gly and L-Pro (Figures S1, S2). 1H NMR analyses of the
acid-digested samples (see ESI) showed substantial level of
amino acid incorporation into UiO-66 and moderate into UiO-67
(Table 1). L-Proline was particularly efficient, affording a high
yield (≥90%) of the MOF in both cases. Importantly, the 5 equiv
of proline loading employed here was a fraction of the commonly
used modulator amounts (≥ 30 equiv), as has also been
observed by Forgan et al.9 The nitrogen sorption on amino acid
modulated MOFs demonstrate high porosity of the samples
(Figure S3, BET SAs: 1270, 1220, 1030 m2/g for UiO-66Pro,
UiO-66Gly and UiO-66Phe correspondingly) despite the high
amino acid loadings. We take this data as evidence that amino
acids are not simply “stuck” inside the pores, but are likely
present as a defect-capping structural elements. Moreover TGA
(Figure S4) show substantial linker deficiency in the studied
samples. As a key observation, proline modulation at 70 °C,
although much less efficient in terms of yield, led to the
formation of X-Ray quality crystals of UiO-67 (Scheme 3a) on
the walls of the reaction vial.

Intrigued by this ability to induce the growth of larger crystals at
lower modulator loading, we tested a wider range of amino acids
(Scheme 3A) as modulators of the formation of UiO-67 at 70 oC.
This screen revealed that while several amino acids do provide
the desired MOF (see pXRD in Figure S5), only proline (L or rac)
appears to have the capacity to generate the material in a single
crystalline form. It would appear, thus, that the steric/electronic
properties balance in proline provides the right conditions for
slower growth of high quality crystals. Addition experiments were
carried out in order to pinpoint the structural parameters
responsible for proline’s unique modulation capacity. The use of
N-formyl proline, detected during the proline-modulated Zr-MOF
synthesis (see below), did not offer single crystals (Scheme 3B,
compare i and ii). Similarly, very small particles were observed
using the pyroglutamic acid or the proline methyl ester
(structures iii and iv), indicating the participation of both the
NH2+ and the CO2H moieties in the modulation phenomenon.
The poorer crystallinity registered for proline’s next higher
homologue, pipecolinic acid (entry vi) was more surprising, and
suggests even more subtle conformational effects on modulating
ability. On the other hand, switching from the hydrochloride to
the trifluoroacetic acid salt of L-proline led to an equally effective
modulation (Figure S6).

Table 1. Performance of three model amino acids as modulators for Zr-MOF
syntheses.

Temp,
°C

Mod
acid

UiO-66

UiO-67

Mod/La

Rangeb

0.5

Microc

0.12

Microd

Gly

1.0

Micro

0.11

Micro

L-Phe
70

Mod/La

L-Pro
120

Rangeb

0.8

Nano

0.14

Nano

L-Pro

0.9

Micro

<0.01

Single

a

Defined as mmol (amino acid)/mmol HO2C-R-CO2H;

b

Micro: (1-10 μm), Nano: (40-300 nm); c Yield: 95%; d: 90%

Scheme 3. A) Amino acid screen in UiO-67 synthesis; B). Proline vs
analogues in modulated synthesis.

As mentioned in the introduction, the generation of X-Ray quality
crystals in Zr-MOF is far from trivial, and proline modulation
appears to constitute a promising “point of attack” in this
endeavor. Thus, proline modulation was applied to a range of
potential linker structures (Figure 1) applying a set of conditions
involving the use of ZrOCl2·8H2O and the in situ generated L-

proline hydrochloride (using HClaq, Method A). We were pleased
to find that while MOF formation was observed in most cases
tested, several of these were obtained in the form of X-ray
quality single crystal (Figure S7). As a proof of concept, in
addition to re-determining the single crystal structures of UiO-67
(reported recently, including by our group11,3b,5b,9e) and of a
methylated UiO-68 derivative (also known as PCN-56),12 we now
prepared and solved the single crystal structure of the previously
unknown UiO-67Cl, and of the NU-801, synthesized from the
1,4-benzenediacrylic acid (Figure 1, Method A). The structure of
the latter had previously been determined from powder X-Ray
analysis, and the new determination corroborates the previous
structure.2e

While a 5-fold excess of L-proline was used to ensure optimal
performance, single crystals could be achieved even with the
stoichiometric quantity of L-Pro (Table S3), once again in sharp
contrast to the classical protocols typically based on a large (≥30
equiv) modulator excess. However, when using the 5 equiv of LPro, diluting the reaction mixture led to smaller particles (Table
S4). For certain linkers, it was observed that conditions
employed in Method A were still insufficient to provide crystals
large enough for conventional structure determination. We
speculated that minimizing the reaction water content (present
through the Zr(IV) hydrate source and also as HCl co-solvent)
might further slow down the reaction, thus aiding in the formation
of larger crystals. Indeed, using the pre-formed isolated LPro·HCl and the anhydrous ZrCl4, large single crystals of UiO67Me and Zr-muc were obtained, allowing in both cases for
structure determination through single crystal X-Ray analysis
(Figure 1, Method B; also Figure 2). In the context of the
formation of a UiO-type network using the 2-Mebiphenylcarboxylic acid, it is interesting to mention the possibility
of an alternative kinetically controlled ligand-deficient structure,
PCN-700, reported recently by Zhou et al for a closely related
2,2’-dimethyl ligand.13 As we see here (and as one might expect),
it appears that having just one 2-Me substituent is insufficient
override the thermodynamic preference for a cubic UiO-67
structure.13b Interestingly, the muconate-derived framework
presents a structure different from that previously determined
from pXRD for the material synthesized by ligand exchange from
pre-formed Zr6 methacrylate clusters.4 While the reported
structure featured the muconic acid in the s-cis conformation
with a framework essentially identical (through disorder) to UiO66 (Figure 2-B’), the single crystal structure of the material
obtained here via proline modulation (Method B) is constructed
with linkers in the extended s-trans conformation. The loss of colinearity between the two RCO2 coordination vectors is reflected
̅
in the lowering of the space group symmetry to Pn3, down from
̅
the Fm3m ubiquitous for this type of networks. Specifically, the
̅
Zr6 cluster now resides on a 3 site, which only imposes a
crystallographic D3d symmetry of a trigonal antiprism. The strut
occupancy was refined to 0.82, meaning that roughly 1 out of 6
muconates is missing, in perfect agreement with proline levels
obtained via digestion NMR of these crystals (0.4 L-Pro / 1
ligand, Table S2).

Figure 2. A) Crystal of the Zr muconate obtained by Method B, and B) the
material’s single crystal X-ray structure. For comparison, the pXRD structure
for the material synthesized from Zr6 methacrylate (ref 4) is shown as B’.
Figure 1. Ligands space explored in the current work for single crystal growth
under 5 eq. L-Pro modulation.

A second corollary of using amino acid modulators is the
potential entry into amino acid-containing MOF structures. We
found a roughly inverse correlation between amino acid
incorporation and crystal size/quality (Tables 1, S2). This meant
respectable levels (up to 1:1 L-Pro : ligand) of proline
incorporation for the less crystalline UiO-66, for Zr-muc
synthesized at low temperature, and for the high temperature
batches of UiO-67, opening a way to control the amino acid
loading. The amino acid binding is assumed to be the normal
carboxylate bidentate coordination, as seen in the crystal
structure of the related discreet Zr6 glycinate.14

As a final note, we briefly tested the effect that the effect of the
modulator would have on the MOF’s carbon capture capacity
(an aspect that has been gained attention from the MOF
community15). Here, we employed samples of UiO-66 prepared
on a multi-gram scale using proline and benzoic acid modulation.
The former (prepared at 120 oC), UiO-66Pro, was found to
contain 0.5:1 N-formyl-L-Pro:ligand); the latter, UiO-66b,3b
contained 0.8:1 benzoate:ligand. Measurements showed (Figure
4) that even though UiO-66Pro is less porous than UiO-66b
(BET SAs 1270 versus 1520 m2/g accordingly), the CO2 uptake
of the latter is 30% higher than that of the former. We tensatively
attribute this increase to a stronger interaction of CO2 with polar
groups introduced via amino acid modulation. The CO 2 sorption
capacity of UiO-66Pro is completely recovered after evacuation
at room temperature.

Figure 3. Fragment of NMR spectra of proline (top), N-formyl proline (middle)
and proline-modulated UiO-66 (bottom).

The digestion NMR analysis in several of our UiO-66 and UiO67 samples revealed that amino acid is included in the form of
the N-formate, presumably through the reaction with DMF
(Figure 3, Schemes 4 and S1), a process that we determined for
various amines to be assisted by the presence of Zr(IV). For
instance, heating a DMF solution of benzyl amine at at 100°C in
the presence of either UiO-66 or ZrOCl2·8H2O for 20h led to the
full conversion into N-formyl benzyl amine.
To confirm that the amino acid is chemically bound to the MOF
(rather than being present as insoluble amorphous admixture),
the recent technique of quantitative defects capping exchange 3b
for a new anion was applied (Scheme 4). Thus, a sample of
UiO-66Pro, for which a close to 1:2 proline-to-terephthalic acid
ratio had been determined by NMR, was immersed into a 4%
AcOH solution in DMF for 20h, and then thoroughly washed with
DMF and acetone. pXRD of the resulting material showed
retention of crystallinity (Figure S12) and nitrogen sorption
demonstrated increased porosity (BET SA 1550 m2/g, Figure
S13) consistent with substitution of formylprolinate with lighter
acetate anion. Indeed, the digestion NMR of the resulting
material showed a close to 1:2 acetic acid to framework ligand
ratio, demonstrating quantitative substitution of the modulator
capping defects with the new acid and lending further evidence
for its position at defect sites.

Scheme 4. UiO-66Pro formation with simultaneous L-Pro formylation followed
by its substitution with acetate for defects content confirmation.

Figure 4. Nitrogen at 77K (left) and CO2 at 300 K (right) sorption for UiO-66Pro
in comparison to related UiO-66b.

Seeking to suppress proline formylation, modulated growth of Zr
MOfs was also tested in other solvents. For environmental
reasons, we are particularly interested in water, which was
already demonstrated to work well for Zr-MOF syntheses.16 We
were pleased to find that water (and also DMSO, Figure S15,
S16) is compatible with amino acid modulation and provides
highly crystalline UiO-66 grafted with non-formylated proline.

Conclusions
Amino acid modulation for Zr-MOF synthesis was developed as
a straightforward way for functionality incorporation and particle
size control. This method (especially with proline) provides ZrMOFs with increased particle size (μm to single crystals)
important for chromatographic/flow chemistry applications and
X-Ray characterization. New Zr-MOF single-crystal structures
were studied as a result. On the other hand amino acid
modulators can be incorporated into Zr-MOFs on defect sites in
0 to 1 ratio to the framework ligand which is controlled by ligands
structure and reaction conditions. With the possibility of bigger
biomolecules (peptides etc.) installation it opens straightforward
opportunities for the design of new hybrid materials for
separations and catalysis. Our amino acid modulated Zr-MOFs
demonstrated improved CO2 capture capacity comparing to nonfunctionalized material.

Experimental Section
General experimental information and additional procedures are provided
in the Supporting information.
Method A for amino acid modulated Zr-MOF synthesis. The solid
ZrOCl2·8H2O (485 mg, 1.51 mmol) and the amino acid modulator (7.53
mmol) were dissolved in a mixture of DMF (20 mL) and hydrochloric acid
37 % (0.625 mL, to convert amino acid to a soluble salt) in a vial (choose
the size in terms of total volume, so that it is as full as possible under a 5
min sonication. The dicarboxylic acid ligand (1.51 mmol) was added and
the mixture was further sonicated for an additional 5 min. The vial was
sealed with a screw cap and was then stored undisturbed in a
temperature-controlled oven preheated to the target temperature (120 ºC
or 70 ºCC, depending on the application requirements, such as
yield/crystallinity/amino acid loading vs. single crystals, according to
Table 1 in the main text) for 4 days. At this point, a part of the
supernatant solution was decanted (the biggest single crystals were
found on the walls of the reaction vessel), and the remaining resulting
precipitate was separated by filtration or centrifugation (for nano-crystals)
and washed with DMF (5 x 20 mL). For UiO-66Gly synthesis DMF-water
(3:2 ratio) was used for washings instead of DMF to remove Gly
byproducts. Each washing cycle consisted in adding the DMF, stirring the
sample with spatula to achieve a homogeneous suspension, allowing the
mixture to repose for 30 min, and then isolating the precipitate. The same
procedure was then repeated with THF washes (5 x 20 mL). To remove
the solvents from the pores (activate), the material was evacuated 5 h at
room temp., and then for 15 h at 120 0C at a ramp of 1 0C/min.
X-Ray structure determination. All the structures determined by X-ray
diffraction during this work have been deposited in the Cambridge
Structural database.17

[3]

[4]
[5]

[6]

[7]

Acknowledgements
[8]

Financing through grants from the EC (Marie Curie grant to O.
G., FP7-PEOPLE-2013-IIF-623725), Fundació ICIQ, MINECO
(CTQ2013-46705-R and 2014-2018 Severo Ochoa Excellence
Accreditation SEV-2013-0319), the Generalitat de Catalunya
(2014 SGR 1192), and the CELLEX Foundation (through the
CELLEX-ICIQ High Throughput Experimenta-tion platform) is
gratefully acknowledged. Authors are grateful to Phil Abbott from
Reach Separations for fruitful discussions and Georgiana Stoica
from ICIQ for the help with sorption measurements.

[9]

Keywords: Zr-MOF -· Amino acids • proline • modulation • Zr
MOF defect• functional MOFs

[10]

[1]

[11]

[2]

a) J. H. Cavka, S. Jakobsen, U. Olsbye, N. Guillou, C. Lamberti, S.
Bordiga and K. P. Lillerud, J. Am. Chem. Soc. 2008, 130, 13850-13851;
for pioneering work on the Zr6 carboxylate clusters, see b) G. Kickelbick,
U. Schubert Chem. Ber. 1997, 130, 473; c) G. Kickelbick, U. Schubert,
J. Chem. Soc., Dalton Trans. 1999, 1301–1305; d) M. Puchberger, F. R.
Kogler, M. Jupa, S. Gross, H. Fric, G. Kickelbick, U. Schubert, Eur. J.
Inorg. Chem. 2006, 3283–3293.
a) T.-F. Liu, D. Feng, Y.-P. Chen, L. Zou, M. Bosch, S. Yuan, Z. Wei, S.
Fordham, K. Wang and H.-C. Zhou, J. Am. Chem. Soc. 2015, 137, 413419; b) D. Feng, K. Wang, J. Su, T.-F. Liu, J. Park, Z. Wei, M. Bosch, A.
Yakovenko, X. Zou and H.-C. Zhou, Angew. Chem. Int. Ed. 2015, 54,
149-154; c) K. Na, K. M. Choi, O. M. Yaghi, G. A. Somorjai, Nano Lett.

[12]
[13]

[14]

2014, 14, 5979-5983; d) J. Jiang, F. Gándara, Y.-B. Zhang, K. Na, O. M.
Yaghi, W. G. Klemperer, J. Am. Chem. Soc. 2014, 136, 12844-12847;
e) D. A. Gomez-Gualdron, O. V. Gutov, V. Krungleviciute, B. Borah, J.
E. Mondloch, J. T. Hupp, T. Yildirim, O. K. Farha, R. Q. Snurr, Chem.
Mater. 2014, 26, 5632-5639; f) O. V. Gutov, W. Bury, D. A. GomezGualdron, V. Krungleviciute, D. Fairen-Jimenez, J. E. Mondloch, A. A.
Sarjeant, S. S. Al-Juaid, R. Q. Snurr, J. T. Hupp, T. Yildirim, O. K.
Farha, Chem. Eur. J. 2014, 20, 12389-12393; g) Z.-M. Zhang, T. Zhang,
C. Wang, Z. Lin, L.-S. Long, W. Lin, J. Am. Chem. Soc. 2015, 137,
3197-3200; h) M. S. Denny, S. M. Cohen, Angew. Chem. Int. Ed. 2015,
54, 9029-9032; i) H. Fei, S. M. Cohen, J. Am. Chem. Soc. 2015, 137,
2191-2194; j) G. Nickerl, I. Senkovska, S. Kaskel, Chemical Commun.
2015, 51, 2280-2282; k) for a review on the topologies in Zr MOFs, see:
N. Stock, S. Biswas, Chem. Rev. 2012, 112, 933–969.
a) A. Schaate, P. Roy, A. Godt, J. Lippke, F. Waltz, M. Wiebcke and P.
Behrens, Chem. Eur. J. 2011, 17, 6643-6651. (b) O. V. Gutov, M. G.
Hevia, E. C. Escudero-Adán and A. Shafir, Inorg. Chem. 2015, 54,
8396-8400.
V. Guillerm, S. Gross, C. Serre, T. Devic, M. Bauer and G. Ferey,
Chem. Comm. 2010, 46, 767-769.
(a) C. A. Trickett, K. J. Gagnon, S. Lee, F. Gándara, H.-B. Bürgi and O.
M. Yaghi, Angew. Chem. Int. Ed. 2015, 54, 11162-11167. (b) Øien, D.
Wragg, H. Reinsch, S. Svelle, S. Bordiga, C. Lamberti and K. P. Lillerud,
Cryst. Growth Des. 2014, 14, 5370-5372.
(a)
D. Yang, S. O. Odoh, T. C. Wang, O. K. Farha, J. T. Hupp, C. J.
Cramer, L. Gagliardi and B. C. Gates, J. Am. Chem. Soc. 2015, 137,
7391-7396. for increasing catalytic activity in Zr MOF through
modulation, see (b) 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.
(a)
M. Kim, S. M. Cohen, CrystEngComm, 2012, 14, 4096-4104. (b)
W. Lu, Z. Wei, Z.-Y. Gu, T.-F. Liu, J. Park, J. Park, J. Tian, M. Zhang, Q.
Zhang, T. Gentle Iii, M. Bosch and H.-C. Zhou, Chem. Soc. Rev. 2014,
43, 5561-5593. (c) C. Kutzscher, H. C. Hoffmann, S. Krause, U. Stoeck,
I. Senkovska, E. Brunner and S. Kaskel, Inorg. Chem. 2015, 54, 10031009.
For defect control in gas sorption, see H. Wu, Y. S. Chua, V.
Krungleviciute, M. Tyagi, P. Chen, T. Yildirim and W. Zhou, J. Am.
Chem. Soc. 2013, 135, 10525-10532.
a) R. J. Marshall, C. L. Hobday, C. F. Murphie, S. L. Griffin, C. A.
Morrison, S. A. Moggach; R. S. Forgan J. Mater. Chem. A, 2016, 4,
6955-6963; b) R. J. Marshall, S. L. Griffin, C. Wilson, R. S. Forgan, J.
Am. Chem. Soc. 2015, 137, 9527-9530; c) R. J. Marshall, T. Richards,
C. L. Hobday, C. F. Murphie, C. Wilson, S. A. Moggach, T. D. Bennett,
R. S. Forgan, Dalton Trans. 2016, 45, 4132-4135; d) R. J. Marshall, S.
L. Griffin, C. Wilson, R. S. Forgan, Chem. Eur. J. 2016, 22, 4870 –
4877; e) C. Hobday, R. J. Marshall, C. F. Murphie, T. Richards, D.
Allan, T. Duren, F.-X. Coudert, R. S. Forgan, C. A. Morrison, S. A.
Moggach, T. D. Bennett, Angew. Chem. Int. Ed. 2016, 55, 2401–2405;
Angew. Chem. 2016, 128, 2447–2451.
S.-Y. Zhang, D. Li, D. Guo, H. Zhang, W. Shi, P. Cheng, L. Wojtas, M. J.
Zaworotko, J. Am. Chem. Soc. 2015, 137, 15406-5409.
a) G. Nickerl, M. Leistner, S. Helten, V. Bon, I. Senkovska, S. Kaskel,
Inorg. Chem. Front. 2014, 1, 325-330; b) N. Ko, J. Hong, S. Sung, K. E.
Cordova, H. J. Park, J. K. Yang, J. Kim, Dalton Trans. 2015, 44, 20472051.
H.-L. Jiang, D. Feng, T.-F. Liu, J.-R. Li, H.-C. Zhou, J. Am. Chem. Soc.
2012, 134, 14690-14693.
a) S. Yuan, W. Lu, Y.-P. Chen, Q. Zhang, T.-F. Liu, D. Feng, X. Wang,
J. Qin, H.-C.Zhou, J. Am. Chem. Soc. 2015, 137, 3177−3180; b)
caution should be taken when interpreting this difference, as our
conditions are different from those employed by Zhou et al.
L. Pan, R. Heddy, J. Li, C. Zheng, X.-Y. Huang, X. Tang, L. Kilpatrick,
Inorg. Chem. 2008, 47, 5537-5539.

[15]

[16]

[17]

A. M. Fracaroli, H. Furukawa, M. Suzuki, M. Dodd, S. Okajima, F.
Gándara, J. A. Reimer, O. M. Yaghi, J. Am. Chem. Soc. 2014, 136,
8863-8866.
(a) H. Reinsch, B. Bueken, F. Vermoortele, I. Stassen, A. Lieb, K.-P.
Lillerud, D. De Vos, CrystEngComm 2015, 17, 4070-4074. (b) H.
Reinsch, I. Stassen, B. Bueken, A. Lieb, R. Ameloot, D. De Vos,
CrystEngComm 2015, 17, 331-337.
All the structures determined by X-ray diffraction during this work have
been deposited in the Cambridge Structural database under CCDC
numbers 1453411- 1453416.

Entry for the Table of Contents (Please choose one layout)

FULL PAPER
Oleksii V. Gutov,* Sonia Molina,
Eduardo C. Escudero-Adán, Alexandr
Shafir*
Page No. – Page No.

Text for Table of Contents

Modulation by amino acids: towards
superior control in Zr-MOFs
synthesis