Phosphorescence at Low Temperature by External Heavy-Atom Effect in Zinc(II) Clusters

Article abstract of DOI:10.1002/chem.201900343

Luminescent Zn^II clusters [Zn₄L₄(μ₃-OMe)₂X₂] (X=SCN (1), Cl (2), Br (3)) and [Zn₇L₆(μ₃-OMe)₂(μ₃-OH)₄]Y₂ (Y=I^? (4), ClO₄^? (5)), HL=methyl-3-methoxysalicylate, exhibiting blue fluorescence at room temperature (λ_max=416≈429 nm, Φ_em=0.09–0.36) have been synthesised and investigated in detail. In one case the external heavy-atom effect (EHE) arising the presence of iodide counter anions yielded phosphorescence with a long emission lifetime (λ_max=520 nm, τ=95.3 ms) at 77 K. Single-crystal X-ray structural analysis and time-dependent density-functional theory (TD-DFT) calculations revealed that their emission origin was attributed to the fluorescence from the singlet ligand-centred (¹LC) excited state, and the phosphorescence observed in 4 was caused by the EHE of counter anions having strong CH?I interactions.

Full text of DOI:10.1002/chem.201900343

DOI: 10.1002/chem.201900343
Communication
&
Cluster Compounds
Phosphorescence at Low Temperature by External Heavy-Atom
Effect in Zinc(II) Clusters
Fumiya Kobayashi,[a] Ryo Ohtani,[a] Saki Teraoka,[a] Masaki Yoshida,[b] Masako Kato,[b]
Yingjie Zhang,[c] Leonard F. Lindoy,[d] Shinya Hayami,*[a, e] and Masaaki Nakamura*[a]
significant issue for their continuing use in luminescent de-
Abstract: Luminescent ZnII clusters [Zn4L4(m3-OMe)2X2] (X=
vices. Construction of luminescent ZnII complexes is, therefore,
SCN (1), Cl (2), Br (3)) and [Zn7L6(m3-OMe)2(m3-OH)4]Y2 (Y=
an attractive alternative approach for developing novel func-
À
IÀ (4), ClO4 (5)), HL=methyl-3-methoxysalicylate, exhibit-
tional luminescent materials.[6] ZnII complexes have a further
ing blue fluorescence at room temperature (lmax =416
advantage in that their use can facilitate the otherwise relative-
ꢀ429 nm, Fem =0.09–0.36) have been synthesised and in-
ly difficult to obtain blue emission because most such com-
vestigated in detail. In one case the external heavy-atom
plexes show luminescence based solely on a ligand-centred
effect (EHE) arising the presence of iodide counter anions
(LC) transition.[7] However, it can be difficult to obtain long life-
yielded phosphorescence with a long emission lifetime
time phosphorescence and to control emission wave lengths
(lmax =520 nm, t=95.3 ms) at 77 K. Single-crystal X-ray
because of the weak SOC commonly exhibited by ZnII com-
structural analysis and time-dependent density-functional
plexes, with exceptions being several ZnII-based luminescent
theory (TD-DFT) calculations revealed that their emission
metal-organic frameworks (MOFs).[8] In the present study we
origin was attributed to the fluorescence from the singlet
focused on a strategy involving application of an external
ligand-centred (1LC) excited state, and the phosphores-
heavy-atom effect (EHE) that introduces SOC into ZnII clusters.
cence observed in 4 was caused by the EHE of counter
anions having strong CHÀI interactions.
It is considered that the EHE is executed through orbital inter-
actions between the heavy-atoms and the luminophore, result-
ing in increases of both the intersystem crossing (ISC) rates
and the phosphorescence decay time of the excited-state lumi-
nophore.[9] Although the EHE has been routinely utilized to
Luminescent transition-metal complexes have attracted much
promote the phosphorescence of organic molecules,[10] very
attention because of their characteristic photophysical proper-
ties that, for example, have led to the development of organic
light-emitting devices (OLEDs),[1] chemical sensors,[2] molecular
probes,[3] and photosensitizers.[4] Transition-metal complexes,
particularly those of IrIII, PtII, RuII, and AuI, have been well stud-
ied due to their tendency to display strong emission as well as
spin-orbit coupling (SOC), reflecting the presence of the heavy-
metal centres.[5] However, the high cost of those metals is a
few reports of the application of the EHE to metal complex
systems have appeared. In this study, we have designed and
synthesised cationic ZnII clusters with heavy-atom counter
anions. Clusters are a particularly suitable class of materials for
achieving high quantum yields because their structural rigidity
leads to thermo- and photostability relative to smaller mono-
or dinuclear complexes.[11]
Herein, we report the presence of anion-dependent blue
emissions with high luminescence quantum yields and phos-
phorescence associated with the EHE in ZnII clusters of type
[Zn4L4(m3-OMe)2X2] (HL=methyl-3-methoxysalicylate; X=SCN,
[a] F. Kobayashi, Dr. R. Ohtani, S. Teraoka, Prof. Dr. S. Hayami,
Dr. M. Nakamura
Department of Chemistry, Graduate School of Science and Technology
Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto
860-8555 (Japan)
À
Cl, Br) and [Zn7L6(m3-OMe)2(m3-OH)4]Y2 (Y=IÀ, ClO4 ).
The three tetranuclear ZnII clusters [Zn4L4(m3-OMe)2X2] (X=
SCN (1), Cl (2), Br (3)) and two wheel-type heptanuclear ZnII
E-mail: hayami@kumamoto-u.ac.jp
m_nakamura@kumamoto-u.ac.jp
À
clusters [Zn7L6(m3-OMe)2(m3-OH)4]Y2 (Y=IÀ (4), ClO4 (5)) were
[b] Dr. M. Yoshida, Prof. Dr. M. Kato
Department of Chemistry, Faculty of Science, Hokkaido University
North-10 West-8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)
synthesized using the methods, with minor modification, re-
ported previously by us.[12] A 1:1:1 mixture of the required ZnII
salt, HL and triethylamine in methanol was stirred for 30 min
at room temperature and the resultant solution was allowed
to stand for a few days. 1, 2, 3, and 5 were obtained as
colourless crystals while 4 was obtained as yellow crystals
(Scheme 1). Elemental analyses for 1–5 were in accord
with their formulations as [Zn4L4(m3-OMe)2(SCN)2], [Zn4L4(m3-
[c] Dr. Y. Zhang
Australian Nuclear Science and Technology Organization
Locked Bag 2001, Kirrawee DC, NSW, 2232 (Australia)
[d] Prof. Dr. L. F. Lindoy
School of Chemistry, The University of Sydney, NSW 2006 (Australia)
[e] Prof. Dr. S. Hayami
Institute of Pulsed Power Science (IPPS), Kumamoto University
2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555 (Japan)
OMe)2(Cl)2]·0.5CH3OH,
[Zn4L4(m3-OMe)2(Br)2]·0.25CH3OH,
Supporting information and the ORCID identification number(s) for the
author(s) of this article can be found under:
https://doi.org/10.1002/chem.201900343.
[Zn7L6(m3-OMe)2(m3-OH)4]I2·H2O, and [Zn7L6(m3-OMe)2(m3-OH)4]-
(ClO4)2·4.5CH3OH, respectively.
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Scheme 1. Synthesis scheme for 1–5.
Single-crystal X-ray structural analyses for 1–5 were carried
out at 100 or 123 K (see Figure 1). Crystallographic data is dis-
played in Table S1, Supporting Information. Individual struc-
tures of the tetranuclear ZnII clusters 1–3 are shown in Fig-
ure S1, Supporting Information. Each consists of a “defective”
cessible area volume for 1–5 were calculated by Crystal Explor-
er[13] and PLATON[14] (Figure S8, Supporting Information). The
results are listed in Table S2 and S3, Supporting Information.
The calculations revealed that 1–5 have 9.7, 3.6, 5.0, 8.3, 10.4%
crystal voids per one-cell unit, which contain solvent accessible
area volume ratios of 2.0, 0, 0, 1.6, 3.8%, respectively.
UV/Vis absorption and emission spectra of the HL ligand in
the solid state at room temperature are shown in Figure 2. The
UV/Vis absorption spectrum shows an absorption band (labs
=
1
318 nm) attributed to the pp* transition while the emission
Figure 1. Crystal structures of the tetranuclear ZnII clusters [Zn4L4(m3-
OMe)2X2] (X=SCN, Cl, Br) (1–3) and heptanuclear ZnII clusters [Zn7L6(m3-
OMe)2(m3-OH)4]Y2 (Y=IÀ, ClO4À) (4, 5). Hydrogen atoms, counter anions and
solvent molecules are omitted for clarity.
double-cubane core [Zn4O6] in which four ZnII ions are bridged
by m3-methoxo groups and m2-O atoms of the deprotonated
methyl-3-methoxysalicylate ligands (Figure S1d, Supporting In-
formation). In 1, two different octahedral ZnII coordination
spheres are present (Figure S1e, Supporting Information). One
is formed by six oxygen atoms: four arising from carbonyl and
bridging phenoxo groups on the LÀ ligands and two from
bridging methoxo groups. The other is formed by an anion
and five oxygen atoms: four arising from methoxy and bridg-
ing phenoxo groups on the LÀ ligands and one from a bridg-
ing methoxo group. Compounds 2 and 3 have similar struc-
tures to 1 except that they contain two five-coordinated ZnII
ions which lack coordinating methoxy groups from the LÀ li-
gands (Figure S1b,c, Supporting Information). The crystal struc-
tures of the wheel-type heptanuclear ZnII clusters 4 and 5 are
shown in Figure S2, Supporting Information. Each consist of a
divalent cationic heptanuclear cluster, [Zn7L6(m3-OMe)2(m3-
Figure 2. UV absorption spectrum (red line, labs =318 nm) and emission
spectrum (blue line, lex =318 nm, lmax =402 nm) of HL in the solid state at
room temperature.
spectrum displays a fluorescence band (lmax =402 nm) attribut-
1
ed to the pp* transition. The solid-state excitation and emis-
sion spectra of 1–5 at room temperature and 77 K are shown
in Figure 3 and Figure S9, Supporting Information. At room
temperature, the solid (crystalline) samples of 1–3 each exhib-
ited blue luminescence. The emission spectra for 1–3 show un-
structured broad emission bands with maxima (lmax) at 416,
422, and 418 nm, respectively. Although slight changes in the
maxima for 1–3 are observed, the emission spectra are quite
similar. When compared with the emission maximum for HL,
the maxima for 1–3 are significantly shifted. These differences
are in accord with an increase in the HOMO energy in each
case reflecting the different electronegativities between a
proton and the ZnII ion.[7b] The above observations for 1–3 indi-
cate that the emission maxima are essentially not affected by
the coordinating anions. The solid-state excitation and emis-
sion spectra of 4 and 5 at room temperature and 77 K are
À
OH)4]2+, with their respective counter anions (IÀ or ClO4 ). The
seven ZnII ions are bridged by two m3-OMe, four m3-OH, six phe-
noxo and six alkoxo groups to form a Zn7 wheel core display-
ing a Zn@Zn6 arrangement. The central ZnII ion is coordinated
by two methoxo- and four hydroxo-groups with the ZnÀO
bond lengths spanning 2.096(9)–2.125(8) ꢁ. The peripheral ZnII
ions are coordinated by one methoxy, one carbonyl, and two
deprotonated phenol groups from LÀ ligands, with ZnÀO bond
lengths of 1.991(9)–2.295(9) ꢁ. The crystal void and solvent ac-
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Table 1. Photophysical data for 1–5 in the solid state at 298 K.
[d]
[e]
lmax [nm][a]
F[b]
tav [ns][c]
kr [sÀ1
]
knr [sÀ1
]
1
2
3
4
5
416
422
418
424
429
0.36
0.29
0.23
0.09
0.29
4.84
7.64
4.45
2.26
5.40
7.4ꢂ107
3.8ꢂ107
5.2ꢂ107
4.0ꢂ107
5.4ꢂ107
1.3ꢂ108
9.3ꢂ107
1.7ꢂ108
4.0ꢂ108
1.3ꢂ108
[a] Emission maximum, lex =330 nm. [b] Emission quantum yields, lex
=
340 nm. [c] Averaged emission lifetimes, lex =340 nm. [d] Radiative rate
constants, estimated from F/tav. [e] Nonradiative rate constants, estimat-
ed from kr(1ÀF)/F.
298 K. Compound 5 exhibited a similar emission quantum
yield to 1–3 of 0.29, whereas 4 showed a significantly smaller
value at 0.09 than found for the others. This smaller value is
likely due to ISC generated by the external heavy-atom effect
(EHE) of the iodide counterions present in this case.[11] The
shoulder present in the spectrum of 4 around 520 nm at 77 K
was associated with a remarkably long emission lifetime of t=
95.3 ms, in agreement with this emission band resulting from
phosphorescence involving the lowest-excited triplet state (T1
state). An emission quantum yield (F) of 4 at 77 K was evaluat-
ed at 0.32. An emission spectrum of 4 at 77 K, measured after
a delay time of 100 ms after the excitation, clearly exhibited a
broad phosphorescence band with the maximum at lphos
=
Figure 3. Luminescence spectra of ZnII clusters 1–5 in the solid state at
a) room temperature and b) 77 K.
520 nm (Figure 4). Although this phosphorescence was not ob-
served at room temperature due to the thermal deactivation,
overall, the results illustrate the significant contribution of trip-
let excited states of 4 generated by the EHE (arising from the
presence of the iodine ions).
shown in Figure S9, Supporting Information. At room tempera-
ture, crystalline samples of 4 and 5 also exhibited blue lumi-
nescence. Emission spectra for 4 and 5 showed unstructured
broad emission bands with the maxima (lmax) occurring at 424
and 429 nm, respectively. Each showed related photolumines-
cent behaviour to 1–3, indicating a contribution of the intrali-
To investigate the relationship between structures and emis-
sion origins for resultant clusters, DFT and TDDFT calculations
for 2 were carried out because 2 is suitable molecular size for
calculations rather than 4, which consists of large heptanuclear
clusters. The HOMO and LUMO are shown in Figure S12, Sup-
porting Information (Table S5 and S6, Supporting Information).
1
gand pp* transition to their luminescence. These results serve
to demonstrate that differences in the coordinated environ-
ments of the ZnII ions and also the number of ZnII ions in the
clusters do not greatly affect their emission maxima. Impor-
tantly, in the spectrum of 4, a shoulder around 520 nm was ob-
served at 77 K, which is assignable to the phosphorescence, in
addition to the emission band at 425 nm. CIE 1931 coordinates
for emission spectra of 1–5 clearly show the emission colour
change of 4 from deep blue to pale blue based on the expres-
sion of phosphorescence at low temperature (Figure S10,
Table S4, Supporting Information), while the emission colours
of 1–3 and 5 were almost unchanged even at 77 K.
Emission lifetimes (t) and emission quantum yields (F) were
measured for 1–5 (Table 1, Figure S11, Supporting Information).
Each of 1–5 have emission lifetimes in the nanosecond range,
1 (tav =4.84 ns), 2 (tav =7.64 ns), 3 (tav =4.45 ns) 4 (tav =
2.26 ns), and 5 (tav =5.40 ns), which are in accord with expect-
Figure 4. Excitation (dotted lines) and emission (solid lines) spectra of 4 in
the solid state at 77 K. Red and blue lines represent steady-state emission
(lex =330 nm, lem =450 nm) and phosphorescence spectra (lex =330 nm,
lem =550 nm, delay time=100 ms), respectively.
1
ed values arising from intraligand pp* transitions in ZnII com-
plexes.[7] Emission quantum yields (F) of 1–3 were found to
decrease slightly in the order of 1 (0.36), 2 (0.29), 3 (0.23) at
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The singlet excited states were also calculated for 2 by using
TDDFT. The lowest energy of the spin-allowed electronic verti-
cal transitions [DE(S0ÀS1)] was 3.69 eV (336 nm) (Figure 5, see
Table S7, Supporting Information). These results support that
the S1 state of 2 is singlet ligand-centred (1LC) excited state
Aid for Scientific Research on Innovative Areas (Mixed Anion
JP17H05485, and Soft Crystals JP17H06367). This work was par-
tially supported by the Cooperative Research Program of the
“Network Joint Research Centre for Materials and Devices”. The
single crystal data for 1, 4, and 5 were collected on the MX1
beamline at the Australian Synchrotron, a part of ANSTO. The
computations were performed using the Research Center for
Computational Science, Okazaki, Japan.
Conflict of interest
The authors declare no conflict of interest.
Keywords: external heavy-atom effect
·
long emission
lifetime · luminescence · phosphorescence · zinc
Figure 5. Natural transition orbitals for the key vertical excitation of 2, in
which f refers to the oscillator strength. The highest occupied transition or-
bital (HOTO) and the lowest unoccupied transition orbital (LUTO), show the
occupied “hole” and the unoccupied “electron”, respectively, for this excita-
tion.
[1] a) J. Lee, H.-F. Chen, T. Batagoda, C. Coburn, P. I. Djurovich, M. E. Thomp-
son, S. R. Forrest, Nat. Mater. 2016, 15, 92–98; b) Y.-L. Tung, S.-W. Lee, Y.
Chi, L.-S. Chen, C.-F. Shu, F.-I. Wu, A. J. Carty, P.-T. Chou, S.-M. Peng, G.-H.
Lee, Adv. Mater. 2005, 17, 1059–1064; c) J. Zhang, C. Duan, C. Han, H.
Yang, Y. Wei, H. Xu, Adv. Mater. 2016, 28, 5975–5979; d) C.-W. Hsu, C.-C.
Lin, M.-W. Chung, Y. Chi, G.-H. Lee, P.-T. Chou, C.-H. Chang, P.-Y. Chen, J.
Am. Chem. Soc. 2011, 133, 12085–12099.
and that the intraligand transition occurs from the ligand p
HOMO delocalized in the benzene rings and methoxy groups
to the ligand p* LUMO delocalized in the benzene rings and
carbonyl groups. A similar origin for the emission is anticipated
for each of 1–5 due to their similar photoluminescence spectra
and radiative rate constants. In the case of 4, strong CHÀI in-
teractions between the ligand and counter anion (IÀ) are ob-
served (Figure S13 and S14, Supporting Information). For 5, al-
though many hydrogen bonds are present between the ligand
[2] a) L. Fabbrizzi, A. Leone, A. Taglietti, Angew. Chem. Int. Ed. 2001, 40,
3066–3069; Angew. Chem. 2001, 113, 3156–3159; b) M. J. Katz, T. Ram-
nial, H.-Z. Yu, D. B. Leznoff, J. Am. Chem. Soc. 2008, 130, 10662–10673;
c) S. Rochat, J. Gao, X. Qian, F. Zaubitzer, K. Severin, Chem. Eur. J. 2010,
16, 104–113; d) P. Wu, J. Wang, C. He, X. Zhang, Y. Wang, T. Liu, C.
Duan, Adv. Funct. Mater. 2012, 22, 1698–1703; e) S. M. Borisov, R.
Pommer, J. Svec, S. Peters, V. Novakova, I. Klimant, J. Mater. Chem. C
2018, 6, 8999–9009.
[3] a) M. H. Lim, D. Xu, S. J. Lippard, Nat. Chem. Biol. 2006, 2, 375–380;
b) K. K.-W. Lo, K. Y. Zhang, RSC Adv. 2012, 2, 12069–12083; c) K. K.-W.
Lo, Acc. Chem. Res. 2015, 48, 2985–2995; d) K. Y. Zhang, Q. Yu, H. Wei,
S. Liu, Q. Zhao, W. Huang, Chem. Rev. 2018, 118, 1770–1839.
À
and the ClO4 counter anions occur (Figure S15, Supporting In-
formation), no phosphorescence was observed. The above
contrasting behaviour is in keeping with 4 exhibiting orbital in-
teractions between the ligand and the IÀ counter anion that
give rise to the EHE promoting the ISC rates, yielding the phos-
[4] a) H. Ali, J. E. van Lier, Chem. Rev. 1999, 99, 2379–2450; b) C.-Y. Chen, S.-
J. Wu, C.-G. Wu, J.-G. Chen, K.-C. Ho, Angew. Chem. Int. Ed. 2006, 45,
5822–5825; Angew. Chem. 2006, 118, 5954–5957; c) W. M. Campbell,
K. W. Jolley, P. Wagner, K. Wagner, P. J. Walsh, K. C. Gordon, L. S. Mende,
M. K. Nazeeruddin, Q. Wang, M. Grꢃtzel, D. L. Officer, J. Phys. Chem. C
2007, 111, 11760–11762; d) O. S. Wenger, Coord. Chem. Rev. 2009, 253,
1439–1457; e) H. Huang, B. Yu, P. Zhang, J. Huang, Y. Chen, G. Gasser, L.
Ji, H. Chao, Angew. Chem. Int. Ed. 2015, 54, 14049–14052; Angew.
Chem. 2015, 127, 14255–14258.
[5] a) C.-H. Yang, Y.-M. Cheng, Y. Chi, C.-J. Hsu, F.-C. Fang, K.-T. Wong, P.-T.
Chou, C.-H. Chang, M.-H. Tsai, C.-C. Wu, Angew. Chem. Int. Ed. 2007, 46,
2418–2421; Angew. Chem. 2007, 119, 2470–2473; b) R. D. Costa, E. Ortꢄ,
H. J. Bolink, F. Monti, G. Accorsi, N. Armaroli, Angew. Chem. Int. Ed. 2012,
51, 8178–8211; Angew. Chem. 2012, 124, 8300–8334; c) D.-L. Ma, S. Lin,
W. Wang, C. Yang, C.-H. Leung, Chem. Sci. 2017, 8, 878–889; d) V. Guer-
chais, J.-L. Fillaut, Coord. Chem. Rev. 2011, 255, 2448–2457; e) C. A.
Strassert, C.-H. Chien, M. D. G. Lopez, D. Kourkoulos, D. Hertel, K. Meer-
holz, L. D. Cola, Angew. Chem. Int. Ed. 2011, 50, 946–950; Angew. Chem.
2011, 123, 976–980; f) J. Kavitha, S.-Y. Chang, Y. Chi, J.-K. Yu, Y.-H. Hu, P.-
T. Chou, S.-M. Peng, G.-H. Lee, Y.-T. Tao, C.-H. Chien, A. J. Carty, Adv.
Funct. Mater. 2005, 15, 223–229; g) N. Komiya, M. Okada, K. Fukumoto,
D. Jomori, T. Naota, J. Am. Chem. Soc. 2011, 133, 6493–6496.
3
phorescence caused by LC.[15] Such generation of the EHE via
orbital interaction clearly provides an efficient approach for in-
troducing SOC into complexes associated with a ligand-cen-
tred (LC) transition than via direct coordination of heavy-atoms
as occurs in 1–3.
In conclusion, we have synthesized the luminescent ZnII clus-
ters of types [Zn4L4(m3-OMe)2X2] (X=SCN, Cl, Br) and [Zn7L6(m3-
OMe)2(m3-OH)4]Y2 (Y=IÀ, ClO4À) and demonstrated that iodide
counterions produced the external heavy-atom effect (EHE) for
the expression of the phosphorescence (lmax =520 nm) with
the extremely long emission lifetime (t=95.3 ms). To the best
of our knowledge, this is the first observation of long phos-
phorescence involving the EHE arising from counter anions in
luminescent ZnII clusters.
[6] a) S. C. Burdette, G. K. Walkup, B. Spingler, R. Y. Tsien, S. J. Lippard, J. Am.
Chem. Soc. 2001, 123, 7831–7841; b) M. S. Han, D. H. Kim, Angew. Chem.
Int. Ed. 2002, 41, 3809–3811; Angew. Chem. 2002, 114, 3963–3965; c) R.
Pandey, P. Kumar, A. K. Singh, M. Shahid, P.-Z. Li, S. K. Singh, Q. Xu, A.
Misra, D. S. Pandey, Inorg. Chem. 2011, 50, 3189–3197; d) C.-Y. Sun, X.-L.
Wang, C. Qin, J.-L. Jin, Z.-M. Su, P. Huang, K.-Z. Shao, Chem. Eur. J. 2013,
19, 3639–3645.
Acknowledgements
This work was supported by a KAKENHI Grant-in-Aid for Scien-
tific Research (A) JP17H01200 and also by a JSPS Grant-in-Aid
for Young Scientists (B) JP18K14245 as well as a JSPS Grant-in-
[7] a) S. Wang, Coord. Chem. Rev. 2001, 215, 79–98; b) S.-L. Zheng, X.-M.
Chen, Aust. J. Chem. 2004, 57, 703–712; c) A. Barbieri, G. Accorsi, N. Ar-
&
&
Chem. Eur. J. 2019, 25, 1 – 6
www.chemeurj.org
4
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Communication
maroli, Chem. Commun. 2008, 2185–2193; d) O. Wenger, J. Am. Chem.
Soc. 2018, 140, 13522–13533.
[8] a) S. Yuan, Y.-K. Deng, D. Sun, Chem. Eur. J. 2014, 20, 10093–10098;
b) X. Yang, D. Yan, Chem. Sci. 2016, 7, 4519–4526; c) J. M. Seco, S. P.
YꢅÇez, D. Briones, J. ꢆ. Garcꢄa, J. Cepeda, A. R. Diꢇguez, Cryst. Growth
Des. 2017, 17, 3893–3906.
[11] a) P. S. Kuttipillai, Y. Zhao, C. J. Traverse, R. J. Staples, B. G. Levine, R. R.
Lunt, Adv. Mater. 2016, 28, 320–326; b) M. Xie, C. Han, J. Zhang, G. Xie,
H. Xu, Chem. Mater. 2017, 29, 6606–6610.
[12] F. Kobayashi, R. Ohtani, S. Teraoka, W. Kosaka, H. Miyasaka, Y. Zhang,
L. F. Lindoy, S. Hayami, M. Nakamura, Dalton Trans. 2017, 46, 8555–
8561.
[9] a) M. J. S. Dewar, D. B. Patterson, W. I. Simpson, J. Am. Chem. Soc. 1971,
93, 1032–1034; b) A. K. Chandra, N. J. Turro, A. L. Lyons, Jr., P. Stone, J.
Am. Chem. Soc. 1978, 100, 4964–4968; c) A. A. Mohamed, M. A. R.
Omary, M. A. Omary, J. P. Fackler, Jr., Dalton Trans. 2005, 2597–2602.
[10] a) Y. Zhen, L. Biczok, H. Linschitz, J. Phys. Chem. 1992, 96, 5237–5239;
b) W. Z. Yuan, X. Y. Shen, h. Zhao, J. W. Y. Lam, L. Tang, P. Lu, C. Wang, Y.
Liu, Z. Wang, Q. Zheng, J. Z. Sun, Y. Ma, B. Z. Tang, J. Phys. Chem. C
2010, 114, 6090–6099; c) S. d’Agostino, F. Grepioni, D. Braga, B. Ventura,
Cryst. Growth Des. 2015, 15, 2039–2045; d) M. S. Kwon, Y. yu, C. Coburn,
A. W. Phillips, K. Chung, A. Shanker, J. Jung, G. Kim, K. Pipe, S. R. Forrest,
J. H. Youk, J. Gierschner, J. Kim, Nat. Commun. 2015, 6, 8947; e) Z. Yang,
Z. Mao, X. Zhang, D. Ou, Y. Mu, Y. Zhang, C. Zhao, S. Liu, Z. Chi, J. Xu, Y.-
C. Wu, P.-Y. Lu, A. Lien, M. R. Bryce, Angew. Chem. Int. Ed. 2016, 55,
2181–2185; Angew. Chem. 2016, 128, 2221–2225.
[13] S. K. Wolff, D. J. Grimwood, J. J. McKinnon, M. J. Turner, D. Jayatilaka,
M. A. Spackman, CrystalExplorer 3.1; University of Western Australia,
2012.
[14] A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7–13.
[15] a) O. Bolton, K. Lee, H.-J. Kim, K. Y. Lin, J. Kim, Nat. Chem. 2011, 3, 207–
212; b) X. Sun, B. Zhang, X. Li, C. O. Trindle, G. Zhang, J. Phys. Chem. A
2016, 120, 5791–5797.
Manuscript received: January 23, 2019
Revised manuscript received: February 8, 2019
Version of record online: && &&, 0000
Chem. Eur. J. 2019, 25, 1 – 6
www.chemeurj.org
5
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
&
These are not the final page numbers! ÞÞ

Communication
COMMUNICATION
Luminescent ZnII clusters [Zn4L4(m3-
OMe)2X2] (X=SCN, Cl, Br) and [Zn7L6(m3-
&
Cluster Compounds
À
OMe)2(m3-OH)4]Y2 (Y=IÀ, ClO4 ),
F. Kobayashi, R. Ohtani, S. Teraoka,
M. Yoshida, M. Kato, Y. Zhang,
HL=methyl-3-methoxysalicylate, exhib-
iting blue fluorescence at room temper-
ature (lmax =416ꢀ429 nm, Fem =0.09–
0.36) have been synthesized and investi-
gated in detail (see figure).
L. F. Lindoy, S. Hayami,* M. Nakamura*
&& – &&
Phosphorescence at Low Temperature
by External Heavy-Atom Effect in
Zinc(II) Clusters
&
&
Chem. Eur. J. 2019, 25, 1 – 6
www.chemeurj.org
6
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!