Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor-Filled Channels

Article abstract of DOI:10.1002/chem.201904945

Photon upconversion has enjoyed increased interest in the last years due to its high potential for solar-energy harvesting and bioimaging. A challenge for triplet–triplet annihilation upconversion (TTA-UC) processes is to realize these features in solid materials without undesired phase segregation and detrimental dye aggregation. To achieve this, we combine a palladium porphyrin sensitizer and a 9,10-diphenylanthracene annihilator within a crystalline mesoporous metal–organic framework using an inverted design. In this modular TTA system, the framework walls constitute the fixed sensitizer, while caprylic acid coats the channels providing a solventlike environment for the mobile annihilator in the channels. The resulting solid material shows green-to-blue delayed upconverted emission with a luminescence lifetime of 373±5 μs, a threshold value of 329 mW cm^?2 and a triplet–triplet energy transfer efficiency of 82 %. The versatile design allows straightforward changing of the acceptor amount and type.

Full text of DOI:10.1002/chem.201904945

A Journal of
Accepted Article
Title: Triplet-Triplet Annihilation Upconversion in a MOF with Acceptor-
filled Channels
Authors: Shadab Gharaati, Cui Wang, Christoph Förster, Florian
Weigert, Ute Resch-Genger, and Katja Heinze
This manuscript has been accepted after peer review and appears as an
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To be cited as: Chem. Eur. J. 10.1002/chem.201904945
Link to VoR: http://dx.doi.org/10.1002/chem.201904945
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Triplet-Triplet Annihilation Upconversion in a MOF with Acceptor-
filled Channels
Shadab Gharaati[a]‡, Cui Wang[b,c]‡, Christoph Förster[a], Florian Weigert[b], Ute Resch-Genger[b], and
Katja Heinze[a]*
Photon upconversion enjoys an increasing interest in the last years
due to its high potential for solar energy harvesting and in bio-
imaging. A challenge for triplet-triplet annihilation upconversion
(TTA-UC) processes is to realize these features in solid materials
without undesired phase segregation and detrimental dye
aggregation. To achieve this, we combine a palladium porphyrin
Finally, two acceptors in their T1 states undergo triplet-triplet
annihilation (TTA) yielding one acceptor dye in its S0 state and
one acceptor dye in its S1 state with a quantum yield TTA. The
S1 state emits a high-energy delayed fluorescence with a
quantum yield f (Figure 1a).[8,9,10] The overall internal UC
quantum yield is given by equation 1.
sensitizer and
a
9,10-diphenylanthracene annihilator within
a
UC = ½ ISC TTET TTA f (eq 1).
crystalline mesoporous metal-organic framework using an inverted
design. In this modular TTA system, the framework walls constitute
the fixed sensitizer, while caprylic acid coats the channels providing
a solvent-like environment for the mobile annihilator in the channel.
The resulting solid material shows green-to-blue delayed
upconverted emission with a luminescence lifetime of 3735 µs, a
threshold value of 329 mW cm–2 and a triplet-triplet energy transfer
efficiency of 82%. The versatile design allows straightforward
changing the acceptor amount and type.
The factor ½ accounts for the absorption of two photons that are
converted to a single upconverted photon.
Photon upconversion (UC), that is sometimes also referred to as
anti-Stokes shifted luminescence, spectrally converts two low
energy photons to a single high energy one.[1] UC applications
range from bio-imaging and sensing to solar energy
conversion.[2-5] Classical UC materials comprise rare-earth metal
materials[2-3] and two-photon absorbing dyes.[6] The former
materials suffer from low absorption cross sections while
particularly the latter require very high excitation power densities
for the simultaneous absorption of two photons.[1] An
increasingly used UC process is triplet-triplet annihilation
upconversion (TTA-UC) involving strongly absorbing and
emitting molecules.[7-10] The sensitizer absorbs a low-energy
photon and undergoes intersystem crossing (ISC) from the S1 to
the T1 state with a high quantum yield ISC. This T1 state
transfers its energy to an acceptor (annihilator) by triplet-triplet
energy transfer (TTET) with a quantum yield TTET (Figure 1a).
[a]
Dr. S. Gharaati, Dr. C. Förster, Prof. Dr. K. Heinze
Institute of Inorganic Chemistry and Analytical Chemistry
Johannes Gutenberg University Mainz
Duesbergweg 10-14, 55128 Mainz, Germany
E-mail: katja.heinze@uni-mainz.de
C. Wang, Dr. U. Resch-Genger
[b]
[c]
Division Biophotonics,
Federal Institute for Materials Research and Testing (BAM)
Richard-Willstätter-Str. 11, 12489 Berlin, Germany
C. Wang
Institut für Chemie und Biochemie
Freie Universität Berlin
Figure 1. a) Jablonski diagram of TTA-UC with Pd(TCPP) as sensitizer and
DPA as annihilator and b) design concept for the CA/DPA@PCN-222(Pd)
TTA-UC MOF; Pd(TCPP) as linker and triplet donor; Zr6(µ3-OH)8(OH)8 as
secondary building units (SBUs); DPA as triplet acceptor; CA coordinated to
the SBUs as “solvent” in the hexagonal channels; grey (Zr), red (O), blue (N),
white (C), light blue (Pd), H atoms omitted.
Takustraße 3, 14195 Berlin, Germany
‡ These authors contributed equally.
Supporting information for this article is given via a link at the end of
the document.
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According to spin statistics for the encounter of two triplets,
Mn, FeCl, Co, Ni, Cu and Zn)[28b] is prepared from Pd(TCPP)
and ZrCl4 in a solvothermal reaction (Supporting Information). As
determined by single crystal XRD, the hexagonal unit cell (a = b
= 42.455(7) Å; c = 17.1037(2) Å) of the resulting needle-shaped
crystals (Figure 2a) matches that of PCN-222(FeCl) (a = b =
41.968(7) Å; c = 17.143(2) Å[28b]). In the PCN-222(Pd) Kagomé
structure, the Pd…Pd distances across the small trigonal pore,
the large hexagonal pore and along the channels amount to ~9.9,
16.9 and 19.8 Å, respectively, preventing porphyrin aggregation,
yet enabling efficient energy transfer. The PXRD pattern of the
bulk material matches the simulated pattern using the above unit
cell metrics and Pd instead of FeCl (Figure 2a). The results from
the characterization of the PCN-222(Pd) host by IR (Figure 2b),
UV/Vis absorption, and emission spectroscopy are provided in
the Supporting Information (Figures S1-S2).
TTA,max
=
1/9, although higher values have been reported.[11]
Provided, that ISC, TTET and fluorescence occur with unity
quantum yields, the maximum internal efficiency for TTA-UC can
reach UC = 5.5%. ISC and fluorescence efficiencies are intrinsic
properties of the sensitizer and the annihilator, respectively.
TTET requires an interaction between the sensitizer in its T1
state and the annihilator, while for TTA two annihilators in their
T1 states must collide. Hence, TTET and TTA depend on the
concentration of excited triplets T1 and thus on the excitation
power density, as well as on T1–T1 distances and the annihilator
mobility.[8-11] A general challenge of TTA-UC presents its oxygen
sensitivity due to the efficient energy transfer from the T1 states
to 3O2, generating reactive 1O2 and reducing UC
Rationally designing an efficient TTA-UC system requires
[12-14]
.
sensitizers with ISC close to unity like platinum and palladium
porphyrins, such as PtOEP and PdOEP (H2OEP
=
2,3,7,8,12,13,17,18-octaethylporphyrin) in combination with
annihilators, which feature appropriate energy levels and very
high fluorescence quantum yields like 9,10-diphenylanthracene
(DPA, f(DPA) = 95%, Figure 1a).[8-11] Such dye combinations
result in high UC for optimized concentrations in solution.
The design of energy conversion devices as well as sensor and
reporter systems relies on UC in the solid state. For TTA-UC, the
chromophores are typically dispersed in soft materials, such as
polymers, nanocapsules, or micelles.[15-19] For example, drop-
cast films of PtOEP and DPA show TTA-UC with threshold
excitation power densities Ithresh of several kW cm–2.[20] Rapid
drying of these materials yields a favorable distribution of the
sensitizer in the annihilator matrix and lowers Ithresh to 6.8 W cm–
2 [21]
.
Optimization of the annihilator further reduces phase
segregation and leads to an even lower Ithresh of 1.7 mW cm–2.[22]
However, the interface between the chromophores and the
relative orientation of the chromophores is difficult to control in
less ordered systems. In highly ordered systems, like crystalline
materials, the diffusion length of the triplet excitons can in
principle be controlled and optimized.[23] Very promising
materials and UC properties have been observed for
sensitizer/annihilator systems incorporated spatially controlled
into metal-organic frameworks (MOFs). Examples present MOFs
with anthracene-based linkers and surface-bound palladium
sensitizers (Ithresh = 104 mW cm–2; UC = 0.46%),[24] two MOFs
connected by a heterojunction (Ithresh = 25–117 mW cm–2; UC
=
0.1%),[25] and MOFs with mixed sensitizer/annihilator linkers
(Ithresh = 2.5 mW cm–2; UC = 1.28%)[26]. The confinement of the
porphyrin sensitizers in the MOF reduces detrimental porphyrin
dimerization/aggregation and hence aggregation-induced
luminescence quenching. Other examples combine MOF
annihilators with external mobile sensitizers.[27]
In this study, we combine the sensitizer and the DPA annihilator
within a crystalline mesoporous MOF using an inverted design,
namely immobilizing palladium porphyrin linkers Pd(TCPP) as
sensitizers in the channel walls and placing the mobile DPA in
the channels of the MOF (Figure 1b). To provide an optimum
microenvironment for DPA enabling efficient TTET and TTA
processes, the channels of the chosen MOF with Zr6(µ3-
OH)8(OH)8 SBUs and PCN-222 structure[28] were modified with
caprylic acid (CA; octanoic acid) acting as a solvent for DPA
(Figure 1b).
Figure 2. Experimental and simulated PXRD pattern (fwhm 2 = 0.2°) of PCN-
222(Pd); optical photograph of the crystals immersed in acetone (inset). b) IR
spectra of CA (black), PCN-222(Pd) (green), CA@PCN-222(Pd) (red) and
CA/DPA@PCN-222(Pd) (blue) with the relevant vibrational bands highlighted.
Small and large molecules can penetrate into the large
hexagonal channels of PCN-222(M) ( 3.7 nm), allowing pH
sensing,[29] catalytic reactions,[28b,30-34] adsorptive removal of
molecular species like dyes from solution,[35] as well as loading
and release of drugs[36] [37]
To probe the insertion of the
.
annihilator into the channels of PCN-222(Pd), we used NMR
spectroscopy and a 19F-labelled 1,2,3,4,5,6,7,8-octafluoro-9,10-
bis(4-trifluoromethyl-phenyl) anthracene (DPA-F14). The 19F
NMR resonances of DPA-F14 shift from  = –63 (CF3), –134 (CF)
The palladium derivative PCN-222(Pd) of the well-known
thermally and chemically robust MOF PCN-222(M) series (M =
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and –155 (CF) ppm in solution[38] to  = –64, –130/–134 and –
153 ppm in the crystalline state (Supporting Information, Figures
S3–S4). The splitting of the central resonance is attributed to
different chemical environments in the crystals. DPA-F14 hosted
in DPA-F14@PCN-222(Pd) gives two discernable resonances in
the 19F MAS NMR spectrum at  = –67 and –122 ppm
(Supporting Information, Figure S5). The latter can be ascribed
to CF3 groups interacting with the MOF. The resonances of the
CF moieties are not observed, which is ascribed to the
toluene and in water at 70°C. In toluene, 0.37 mg DPA / mg
CA/DPA@PCN-222(Pd) were released after 5 h, while no
release was observed in water for 2 h (Supporting Information),
confirming the desired retention of the DPA guests in the
hydrophobic host in water.
Oxygen can quench the phosphorescence of palladium
porphyrin like Pd(TCPP) yielding 1O2.[30,34,36] Under illumination
with a 532 nm laser (5.25 mW) in the presence of oxygen in the
MOF channels, this 1O2 formation leads to photobleaching of
dispersion of the resonances by different chemical environments. PCN-222(Pd) and CA/DPA@PCN-222(Pd). Sealing the MOF
These results confirm the successful insertion of DPA-F14 in the
MOF channels[35,36] and suggest that DPA-F14 is disordered and
interacts with the MOF.
with an O2-barrier polymer (polyvinyl alcohol) and applying
Na2SO3 as scavenger cannot completely eliminate Pd(TCPP)
quenching by remaining traces of O2 in the MOF channels.
However, longterm illumination studies reveal, that after a
certain period of time when all residual oxygen in the channels
was consumed, PCN-222(Pd) becomes photostable (Supporting
Information, Figure S10). To exclude even traces of O2 in the
MOF channels, all synthetic post-modification procedures
(desolvation, CA and DPA loading) and optical measurements
were performed under rigorous exclusion of O2. Under these
conditions, PCN-222(Pd) and CA/DPA@PCN-222(Pd) are
photostable (Supporting Information, Figure S11).
As DPA (Supporting Information, Figure S6) and DPA
derivatives show an excimer emission at about 570 nm in neat
films,[39] we decided to provide the DPA molecules in the
channel with a hydrophobic environment, such as a fattly acid to
prevent dye aggregation and to increase the mobility of DPA.[12]
Hence, oleic acid ((9Z)-octadec-9-enoic acid) was mixed with
DPA and the fluorescence recorded. However, under laser
irradiation, DPA and oleic acid seemed to react, possibly by a
cycloaddition reaction.[40] Hence, we employed the photostable
saturated surfactant caprylic acid (CA, C8H16O2). In the as-
synthesized PCN-222(Pd), the Zr6 cluster contains two terminal
OH ligands, one of which points into the hexagonal channel,
providing six OH groups per channel segment for the
functionalization with carboxylic acids (Figure 1b).[33] To assess
the attachment of CA to the SBUs, desolvated PCN-222(Pd)
was first treated at 70°C with CA alone giving CA@PCN-
222(Pd) (Supporting Information). The IR spectrum of
CA@PCN-222(Pd) confirms coating the MOF channels with CA
molecules, involving different binding modes to the SBU, i.e.
hydrogen and coordinative bonds.[41] Only a few CA molecules
exist as hydrogen-bonded dimers[42] in the channels (Supporting
Information for detailed assignments). This provides a rather
non-polar solution-like environment for the DPA acceptor in the
channel enabling mobility of the acceptors in the channels
(Figure 1b).
CA and DPA were then co-inserted into the channels of
desolvated PCN-222(Pd) at 70°C yielding CA/DPA@PCN-
222(Pd). Thanks to the high thermal stability of the PCN-222(M)
MOFs,[28b] the morphology of the CA/DPA@PCN-222(Pd)
crystals and the powder XRD pattern remain intact under these
conditions (Supporting Information, Figure S7). The IR spectrum
reveals a superposition of the bands of the OH and the C=O
stretching vibrations of CA/DPA@PCN-222(Pd) and those of
CA@PCN-222(Pd), suggesting an identical coating of the
channel walls and a solution-like interior. Discernible IR bands of
DPA appear at ~1060, 1026 and 745 cm–1 in CA/DPA@PCN-
222(Pd) (Figure 2b inset; Supporting Information, Figure S8)
confirming the successful co-uptake. UV/Vis absorption spectra
of PCN-222(Pd) and CA/DPA@PCN-222(Pd) further corroborate
the presence of Pd(TCPP) (526/555 nm) and DPA (397 nm),
respectively (Supporting Information, Figure S9). DPA uptake by
CA/DPA@PCN-222(Pd) was determined photometrically to
0.29–0.66 mg DPA / mg PCN-222(Pd). The exact amount
slightly depends on the insertion conditions, i.e. concentration,
temperature, and solvent.[35,36] Without coating the channel walls,
loading of methylene blue and doxorubicin in to PCN-222 gave
0.906 and 1.09 mg / mg MOF, respectively.[35,36] Subsequent
leaking of DPA from CA/DPA@PCN-222(Pd) was studied in
Figure 3. a) TTA-UC luminescence (UCL) intensity of solid CA/DPA@PCN-
222(Pd) as function of increasing excitation power density (emission slit width
15 nm) and b) integrated UCL intensity of CA/DPA@PCN-222(Pd) as a
function of the excitation power density (exc = 532 nm). To avoid direct
excitation of DPA, a 495 nm longpass filter was placed between the 532 nm
laser and the CA/DPA@PCN-222(Pd) sample.
UC luminescence (UCL) spectra of CA/DPA@PCN-222(Pd)
show a blue DPA emission around 440 nm upon excitation at
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532 nm (Figure 3a, video in the Supporting Information).
Excitation-power density dependent UCL measurements confirm
the quadratic dependence expected for TTA-UC at lower power
densities with a slope of 1.840.05 that eventually saturates
(slope 1.010.05). At low excitation intensity (with low T1(DPA)
concentration) the UC emission depends quadratically on the
laser density (weak annihilation limit), while at high laser power
density the UC emission scales linearly with the excitation
density (strong annihilation limit).[9] These observations suggest
that the DPA acceptor molecules diffuse essentially freely in the
MOF channels leading to second and pseudo-first order
reactions under low and high laser intensity, respectively. The
intersection gives a threshold value of Ithresh = 329 mW cm–2
(Figure 3b). This Ithresh is larger than that of the best systems
reported (Ithresh few mW cm–2), but much smaller than that of
typical two-component porphyrin-DPA systems (Ithresh several kW
cm–2).[20-26]
Also, the TTA-UC efficiency will be further enhanced by reducing
the reabsorption of the UC emission caused by Pd(TCPP) and
by optimizing the sensitizer/annihilator interface.[12,22,39,44,45]
Acknowledgements
S. .G. acknowledges the Alexander von Humboldt Foundation
for a Georg Forster Research Fellowship. This work was
supported by the Deutsche Forschungsgemeinschaft (DFG;
grants RE 1203/23-1, RE 1203/12-3). We thank Dr. Mihail
Mondeshki (Mainz, Germany) for the MAS NMR measurements,
Dr. Lothar Fink (Frankfurt, Germany) for powder XRD
measurements, Dr. Dieter Schollmeyer (Mainz, Germany) for
determinations of cell constants and Dr. Yi You and Boyang Xue
(Berlin, Germany) for help with the video.
To verify that the blue DPA emission indeed arises from UC, O2
was introduced on purpose, which led to the immediate
disappearance of the DPA emission band (Supporting
Information, Figure S17). As prompt DPA fluorescence is barely
unaffected by oxygen, this O2-sensitivity clearly evidences the
upconverted emission from DPA.
Keywords: hybrid materials • porphyrins • triplet-triplet
annihilation • metal-organic frameworks • upconversion
[1]
[2]
[3]
F. Auzel, Chem. Rev. 2004, 104, 139–173.
M. Haase, H. Schäfer, Angew. Chem. Int. Ed. 2011, 50, 5808–5829.
a) J. Zhou, Q. Liu, W. Feng, Y. Sun, F. Li, Chem. Rev. 2015, 115, 395–
465; b) Y. Wang, K. Zheng, S. Song, D. Fan, H. Zhang, X. Liu, Chem.
Soc. Rev. 2018, 47, 6473–6485; c) X. Zhu, Q. Su, W. Feng, F. Li,
Chem. Soc. Rev. 2017, 46, 1025–1039.
To further confirm the delayed nature of the DPA fluorescence in
CA/DPA@PCN-222(Pd) originating from the population via
longer lived triplet states, we measured the fluorescence lifetime
of pristine DPA in the solid state (f = 4.00.2 ns) and trapped in
the MOF (Supporting Information, Figures S12-14). Due to the
TTA process in the MOF, the DPA lifetime strongly increases
from 4.0 ns to UC = 3735 µs. Correspondingly, the lifetime of
the porphyrin donor in PCN-222(Pd) (p,0 = 7021 µs) is reduced
in CA/DPA@PCN-222(Pd) (p = 1291 µs) due to the TTET
process (Supporting Information, Figures S15-S16). The TTET
efficiency amounts to TTET = 1 – p/p,0 = 82%. The steady-state
emission spectra measured at several points of the solid
CA/DPA@PCN-222(Pd) sample gave TTET efficiencies
between 77–85%, supporting the time-resolved data (Supporting
Information, Figure S18). According to eq. 1 and assuming ISC
= 100%, TTA = 11.1% (conservative maximum theoretical limit
under saturation conditions)[11], and f(DPA) = 95%, we estimate
UC,max to 4.3% for CA/DPA@PCN-222(Pd). The UC efficiency
might be further increased in the future by reducing the
reabsorption of the UC emission caused by Pd(TCPP)
(Supporting Information, Figure S9).
[4]
a) T. F. Schulze, T. W. Schmidt, Energy Environ. Sci. 2015, 8, 103–
125; b) J. C. Goldschmidt, S. Fischer, Adv. Optical Mater. 2015, 3,
510–535.
[5]
[6]
S. M. Borisov, C. Larndorfer, I. Klimant, Adv. Funct. Mater. 2012, 22,
4360–4368.
a) M. Pawlicki, H. A. Collins, R. G. Denning, H. L. Anderson, Angew.
Chem. Int. Ed. 2009, 48, 3244–3266; b) D. C. Mayer, A. Manzi, R.
Medishetty, B. Winkler, C. Schneider, G. Kieslich, A. Pöthig, J.
Feldmann, R. A. Fischer, J. Am. Chem. Soc. 2019, 141, 11594–11602.
C. A. Parker, C. G. Hatchard, Proc. R. Soc. Lond. A 1962, 269, 574–
584.
[7]
[8]
[9]
T. N. Singh-Rachford, F. N. Castellano, Coord. Chem. Rev. 2010, 254,
2560–2573.
V. Gray, K. Moth-Poulsen, B. Albinsson, M. Abrahamsson, Coord.
Chem. Rev. 2018, 362, 54–71.
[10] L. Huang, E. Kakadiaris, T. Vaneckova, K. Huang, M. Vaculovicova, G.
Han, Biomaterials 2019, 201, 77–86.
[11] Y. Y. Cheng, T. Khoury, R. G. C. R. Clady, M. J. Y. Tayebjee, N. J.
Ekins-Daukes, M. J. Crossley, T. W. Schmidt, Phys. Chem. Chem.
Phys. 2010, 12, 66–71.
[12] H. Kouno, Y. Sasaki, N. Yanai, N. Kimizuka, Chem. Eur. J. 2019, 25,
6124–6130.
In summary, we report a highly modular solid TTA-UC system
comprising of a crystalline, thermally stable PCN-222(Pd) MOF
with CA-coated MOF channels and with a DPA annihilator
embedded in a solution-like environment in the MOF channels.
This solid material displays blue upconverted delayed emission
with a luminescence lifetime of 3735 µs, a threshold value of
329 mW cm–2 and a triplet-triplet energy transfer efficiency of
82% (Supporting Information, Figure S19; video). This optical
application adds another facet to the versatile chemistry of PCN-
222 MOFs. The design concept is also applicable to other TTA-
UC pairs and enables tuning of the UCL color, e.g. by replacing
DPA with other dyes as exemplarily shown for 2,5,8,11-tetra-
tert-butyl-perylene, that yields UCL at 450 nm (Supporting
Information, Figure S20). Current work aims to reduce the
oxygen sensitivity and to increase the retention of the trapped
annihilators in organic environments, e.g. by tuning the chain
length of the carboxylic acid and by coating the MOF surface.[43]
[13] S. Baluschev, K. Katta, Y. Avlasevich, K. Landfester, Mater. Horiz.
2016, 3, 478–486.
[14] M. A. Filatov, S. Baluschev, K. Landfester, Chem. Soc. Rev. 2016, 45,
4668–4689.
[15] A. Turshatov, D. Busko, S. Baluschev, T. Miteva, K. Landfester, New J.
Phys. 2011, 13, 083035.
[16] P. Duan, N. Yanai, N. Kimizuka, J. Am. Chem. Soc. 2013, 135, 19056–
19059.
[17] O. S. Kwon, H. S. Song, J. Conde, H.-I. Kim, N. Artzi, J.-H. Kim, ACS
Nano 2016, 10, 1512–1521.
[18] S. H. C. Askes, W. Pomp, S. L. Hopkins, A. Kros, S. Wu, T. Schmidt, S.
Bonnet, Small 2016, 12, 5579–5590.
[19] Q. Liu, T. Yang, W. Feng, F. Li, J. Am. Chem. Soc. 2012, 134, 5390–
5397.
[20] S. Baluschev, V. Yakutkin, G. Wegner, B. Minch, T. Miteva, G. Nelles,
A. Yasuda, J. Appl. Phys. 2007, 101, 023101.
[21] K. Kamada, Y. Sakagami, T. Mizokuro, Y. Fujiwara, K. Kobayashi, K.
Narushima, S. Hiratad, M. Vachad, Mater. Horiz. 2017, 4, 83–87.
This article is protected by copyright. All rights reserved.

10.1002/chem.201904945
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[22] M. Hosoyamada, N. Yanai, T. Ogawa, N. Kimizuka, Chem. Eur. J.
2016, 22, 2060–2067.
[23] H.-J. Son, S. Jin, S. Patwardhan, S. J. Wezenberg, N. C. Jeong, M. So,
C. E. Wilmer, A. A. Sarjeant, G. C. Schatz, R. Q. Snurr, O. K. Farha, G.
P. Wiederrecht, J. T. Hupp, J. Am. Chem. Soc. 2013, 135, 862–869.
[24] J. M. Rowe, J. Zhu, E. M. Soderstrom, W. Xu, A. Yakovenko, A. J.
Morris, Chem. Commun. 2018, 54, 7798–7801.
[25] M. Oldenburg, A. Turshatov, D. Busko, S. Wollgarten, M. Adams, N.
Baroni, A. Welle, E. Redel, C. Wöll, B. S. Richards, I. A. Howard, Adv.
Mater. 2016, 28, 8477–8482.
[26] J. Park, M. Xu, F. Li, H.-C. Zhou, J. Am. Chem. Soc. 2018, 140, 5493–
5499.
[27] a) S. Ahmad, J. Liu, C. Gong, J. Zhao, L. Sun, ACS Appl. Energy
Mater. 2018, 1, 249−253; b) F. Meinardi, M. Ballabio, N. Yanai, N.
Kimizuka, A. Bianchi, M. Mauri, R. Simonutti, A. Ronchi, M. Campione,
A. Monguzzi, Nano Lett. 2019, 19, 2169−2177.
[28] a) W. Morris, B. Volosskiy, S. Demir, F. Gꢀndara, P. L. McGrier, H.
Furukawa, D. Cascio, J. F. Stoddart, O. M. Yaghi, Inorg. Chem. 2012,
51, 6443–6445; D. Feng, Z.-Y. Gu, J.-R. Li, H.-L. Jiang, Z. Wei, H.-C.
Zhou, Angew. Chem. Int. Ed. 2012, 51, 10307–10310.
[29] B. J. Deibert, J. Li, Chem. Commun. 2014, 50, 9636–9639.
[30] Y. Liu, A. J. Howarth, J. T. Hupp, O. K. Farha, Angew. Chem. Int. Ed.
2015, 54, 9001–9005.
[31] P. Li, R. C. Klet, S.-Y. Moon, T. C. Wang, P. Deria, A. W. Peters, B. M.
Klahr, H.-J. Park, S. S. Al-Juaid, J. T. Hupp, O. K. Farha, Chem.
Commun. 2015, 51, 10925–10928.
[32] P. Deria, D. A. Gꢁmez-Gualdrꢁn, I. Hod, R. Q. Snurr, J. T. Hupp, O. K.
Farha, J. Am. Chem. Soc. 2016, 138, 14449–14457.
[33] T. He, B. Ni, X. Xu, H. Li, H. Lin, W. Yuan, J. Luo, W. Hu, X. Wang,
ACS Appl. Mater. Interfaces 2017, 9, 22732–22738.
[34] K. C. Park, C. Seo, G. Gupta, J. Kim, C. Y. Lee, ACS Appl. Mater.
Interfaces 2017, 9, 38670–38677.
[35] H. Li, X. Cao, X. Zhang, Q. Yu, Z. Zhao, X. Niu, X. Sun, Y. Liu, L. Ma,
Z. Li, RSC Adv. 2017, 7, 16273–16281.
[36] W. Liu, Y.-M. Wang, Y.-H. Li, X.-J. Cai, X.-B. Yin, X.-W. He, Y.-K.
Zhang, Small 2017, 13, 1603459.
[37] Y. Bai, Y. Dou, L.-H. Xie, W. Rutledge, J.-R. Li, H.-C. Zhou, Chem. Soc.
Rev. 2016, 45, 2327–2367.
[38] J. F. Tannaci, M. Noji, J. L. McBee, T. D. Tilley, J. Org. Chem. 2008,
73, 7895–7900.
[39] T. Serevičius, R. Komskis, P. Adomėnas, O. Adomėnienė, V.
Jankauskas, A. Gruodis, K. Kazlauskasa, S. Juršėnasa, Phys. Chem.
Chem. Phys. 2014, 16, 7089–7101.
[40] G. Kaupp, Liebigs Ann. Chem. 1977, 254–275.
[41] M. H. Al-Hazmi, Y. Choi, A. W. Apblett, Adv. Phys. Chem. 2014,
429751.
[42] H. Matsuzawa, M. Tsuda, H. Minami, M. Iwahashi, Food Nutr. Sci.
2013, 4, 25–32.
[43] D. Sun, P. R. Adiyala, S.-J. Yim, D.-P. Kim, Angew. Chem. Int. Ed.
2019, 58, 7405–7409.
[44] M. O. Senge, S. A. MacGowan, J. M. O’Brien, Chem. Commun. 2015,
51, 17031–17063.
[45] C. E. McCusker, F. N. Castellano, Top. Curr. Chem. 2016, 374, 1–25.
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10.1002/chem.201904945
Chemistry - A European Journal
COMMUNICATION
COMMUNICATION
TTA upconversion: Hydrophobic
coated channels of a mesoporous
MOF with palladium porphyrin walls
hosting anthracene acceptors furnish
a stable crystalline material showing
efficient triplet-triplet annihilation
upconversion in the solid state.
S. Gharaati, C. Wang, C. Förster, F.
Weigert, U. Resch-Genger, and K.
Heinze*
Page No. – Page No.
Triplet-Triplet Annihilation
Upconversion in a MOF with
Acceptor-filled Channels
This article is protected by copyright. All rights reserved.