Effects of a side chain aromatic ring on the reactivity of copper(I) complexes with dioxygen

Article abstract of DOI:10.1002/1521-3773(20011015)40:20<3859::AID-ANIE3859>3.0.CO;2-K

Stabilization of the bis(μ-oxo)dicopper(III) intermediate is achieved by using a bidentate N-donor ligand with pendent indole rings: N,N-bis[(3-indolyl)methyl]N-[(2′-pyridyl)methyl]amine (BIP). The intermediate decomposes to give products arising from N-dealkylation and a product with a spiro ring composed of two indole rings (see scheme). This latter product probably results from a radical-coupling reaction.

Full text of DOI:10.1002/1521-3773(20011015)40:20<3859::AID-ANIE3859>3.0.CO;2-K

COMMUNICATIONS
Effects of a Side Chain Aromatic Ring on the
Reactivity of Copper(i) Complexes with
Dioxygen**
BIP : R =
N
N
H
N
R
R
N
Me
BBP : R =
BNP : R =
Yuichi Shimazaki, Takeo Nogami, Fumito Tani,
Akira Odani, and Osamu Yamauchi*
N
N
Me-IMP
N
H
Close contact between a metal ion and an aromatic ring has
been observed for planar metal complexes with an aromatic
ring in the side chain, such as the tryptophan indole and the
tyrosine phenol ring,[1] and for complexes where intramolec-
ular aromatic-ring stacking occurs.[2] We reported previously
that the CuI complex of a tripodal N3 ligand with a pendent
indole ring has a unique CuI indole h2-type bond through the
C2 C3 moiety.[3] A pendent naphthyl group of a CuI complex
of a NS2 macrocyclic ligand has been reported to form a
similar bond.[4]
Scheme 1. Structures of N-donor ligands with pendent aromatic rings.
The bidentate ligand N,N-bis[(3-indolyl)methyl]-N-[(2'-
pyridyl)methyl]amine (BIP) reacted with CuI ions to give a
dimeric complex [Cu(bip)I]2 ´ 2CH3COCH3 (1), the X-ray
crystal structure analysis[16] of which has shown that each CuI
site has a distorted tetrahedral geometry formed by two
bridging iodine atoms, a tertiary amine nitrogen atom, and a
pyridine nitrogen atom (Figure 1). The two side-chain indole
These observations suggest that the proximity of indole or
other aromatic rings to the metal center may affect the
reactivity of the complex, such as in the formation of a metal ±
dioxygen adduct in the course of dioxygen activationÐwhich
is of current interest for its importance in biological as well as
chemical systems.[5] Significant progress has been made in the
chemistry of the intermediate complexes formed in the course
of the reaction of CuI species with dioxygen.[6] trans-m-
Peroxodicopper(ii),[7] (m-h2:h2-peroxo)dicopper(ii),[8] and
bis(m-oxo)dicopper(iii)[9±14] complexes have drawn particular
attention as a consequence of their known or potential
relevance to intermediates in biological oxygenation. The
bis(m-oxo)dicopper(iii) species was characterized by X-ray
crystallography and shown to have a unique diamond-shaped
structure formed by two CuIII and two bridging oxo ions,
Cu2(m-O)2,[9±12] and the reactivities of this and other species
have been explored in connection with the oxidative activa-
tion of C H bonds.[9±15] These intermediates often reacted
with aliphatic C H bonds[15] and in a few cases activated the
aromatic ring.[14]
Figure 1. ORTEP view of [Cu(bip)I]2 ´ 2CH3COCH3 (1) drawn with the
thermal elliposids at the 50% probability level and atomic numbering
scheme (CH3COCH3 molecules omitted for clarity). The hydrogen atoms
and solvents are omitted for clarity. Selected bond lengths [Š] and angles
[8]: Cu(1)-N(1) 2.075(6), Cu(1)-N(2) 2.223(5), Cu(1)-I(1) 2.585(1), Cu(1)-
I(2) 2.625(1); N(1)-Cu(1)-N(2) 79.5(3), N(1)-Cu(1)-I(1) 112.7(2), N(1)-
Cu(1)-I(2) 105.9(2), I(1)-Cu(1)-I(2) 120.51(3).
Here we report that the CuI complexes of N-donor ligands
with one or two pendent indole rings (Scheme 1) form a
dioxygen adduct as an intermediate which decomposes to give
a product formed by a unique radical-coupling reaction
between the indole rings.
rings are uncoordinated, and neither the stacking nor the
CuI indole h2-type bond[3] were detected in the solid state or
in solution. The reaction of a similar ligand, Me-IMP (N-(3-
indolylmethyl)-N-(6-methyl-2-pyridylmethyl)-N-(2-pyridyl-
methyl)amine),[3] and CO with [Cu(CH3CN)4]ClO4 gave
[Cu(Me-imp)(CO)]BPh4 (2), which was revealed to have a
tetrahedral geometry (Figure 2).
[*] Prof. Dr. O. Yamauchi
Faculty of Engineering
Kansai University
Suita, Osaka 564-8680 (Japan)
Fax : (‡81)6-6330-3770
E-mail: osamuy@ipcku.kansai-u.ac.jp
Dr. Y. Shimazaki, Dr. F. Tani
Institute for Fundamental Research of Organic Chemistry
Kyushu University, Higashi-ku, Fukuoka 812-8581 (Japan)
A colorless solution of 1 in THF reacted with O2 at 908C
to give a brown solution with an intense absorption band
centered at 374 nm and a shoulder peak at 516 nm. The
resulting solution was ESR inactive at 77 K. Complex 2 also
reacted with O2 in THF to give a brown solution exhibiting an
absorption spectrum with similar peaks at 379 and 510 nm.[17]
The resonance Raman spectrum of this solution gave a
T. Nogami, Prof. Dr. A. Odani
Graduate School of Science and
Research Center for Materials Science
Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan)
[**] This work was supported by the Grants-in-Aid for Scientific Research
(No. 09304062 to O.Y. and No. 07CE2004 (COE) to A.O.) from the
Ministry of Education, Culture, Sports, Science, and Technology of
Japan, for which we express our sincere thanks.
1
1
Raman peak at 595 cm with 16O2 which shifted to 568 cm
upon substitution with 18O2 (406.7-nm Kr laser excitation;
Figure 3). No peaks were observed in the 700 ± 800 cm
‡
1
Supporting information for this article is available on the WWW under
http://www.angewandte.com or from the author.
region, where the band resulting from the m-peroxo dimer is
Angew. Chem. Int. Ed. 2001, 40, No. 20
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O
III
Cu
III
Cu
[Cu(BIP)I]2
–90°C, THF
O
3
1
H
N
H
O
N
N
CHO
N
N
N
H
N
N
H
H
6
5
4
Scheme 2. Reactions of CuI-BIP complexes with dioxygen.
The formation and decay of the oxygenated species 3
followed the first-order rate law, which indicates that the
peroxo species was not formed or was too unstable to be
detected during the reactions. On the other hand, BBP and
BNP (BBP ˆ N,N-bis(benzyl)-N-[(2'-pyridyl)methyl]amine;
BNP ˆ N,N-bis[(1-naphthyl)methyl]-N-[(2'-pyridyl)methyl]-
amine (Scheme 1)) reacted with CuI to give [Cu(bbp)I] and
[Cu(bnp)I],[20] respectively, and both reacted with O2 in THF
at 908C to give a green color almost instantaneously. In
order to examine the difference in reactivity in detail we
measured the difference spectra for the reaction of [Cu(bnp)I]
with O2 under the same conditions by the rapid-scan
technique. This study revealed a transient shoulder peak at
approximately 380 nm during the first 5 ± 20 s and finally
peaks at around 360 and 600 nm.[17] This observation indicates
that an oxygenated intermediate similar to 3 is also formed
with BNP, but it may be much less stable than that formed
from 1 or 2. This fact suggests there is a stabilizing effect of the
Cu2(m-O)2 core in the complexes by the pendent indole rings.
Intermediate 3 was short-lived compared with some of the
reported Cu2(m-O)2 species and changed to a green species
below 808C. The first-order decay constant kobs of the brown
‡
Figure 2. ORTEP view of the [Cu(Me-imp)(CO)] ion in 2 drawn with the
thermal ellipsoids at the 50% probability level and atomic numbering
scheme. The hydrogen atoms are omitted for clarity. Selected bond lengths
[Š] and angles [8]: Cu(1)-N(1) 2.048(4), Cu(1)-N(2) 2.134(4), Cu(1)-N(3)
2.021(4), Cu(1)-C(1) 1.790(9); N(1)-Cu(1)-N(2) 81.6, N(1)-Cu(1)-N(3)
108.1(2), N(2)-Cu(1)-N(3) 83.4(2), N(1)-Cu(1)-C(1) 122.0(3), N(2)-Cu(1)-
C(1) 125.5(3), N(3)-Cu(1)-C(1) 123.6(2).
Figure 3. Resonance Raman spectra of 2 after oxygenation with 16O2 and
18O2 in THF at 908C (406.7-nm Kr laser excitation).
‡
1
species in THF was estimated to be 1.5 Â 10 2 s (half-life
t
1/2 < 1 min) at 908C, as determined by UV/Vis spectro-
expected. We measured the resonance Raman spectrum with
514.5-nm laser excitation in order to detect the possible
existence of the peroxo species. The spectrum showed a weak
scopy. Indole-3-carboxaldehyde (4; 10%) and N-(3-indolyl)-
methyl-N-[(2'-pyridyl)methyl]amine (5; 10%) were detected
among the decomposition products formed by N-dealkylation
(Scheme 2), which has been reported to occur with other
Cu2(m-O)2 species.[9c, 12] In addition to these products, an
interesting decay product 6 was isolated as crystals (15%).
The X-ray structure analysis[16] of the product disclosed that it
has a bis(indolyl) moiety which is considered to have resulted
from a radical-coupling reaction (Scheme 2).[17] This structure
supports the theory that the indole ring was located suffi-
ciently close to the metal center to undergo an indole C H
bond scission, to form an indolyl radical in the course of the
oxidative decomposition. [Cu(bbp)I] and [Cu(bnp)I] were
observed to undergo N-dealkylation to give the correspond-
ing aldehydes and secondary amines in low yields (<5%), but
no radical-coupling product was detected.
1
1
band at 590 cm , but no peroxo band at about 750 cm . The
absorption and resonance Raman spectra of 3 agreed well
1
with the values of 378 and 494 nm, and 590 cm , respectively,
reported for [Cu2(O)2(Me2-tpa)2]2‡ (Me2-tpa ˆ bis(6-methyl-
2-pyridylmethyl)-2-(pyridylmethyl)amine) which was isolated
and structurally established by Suzuki and co-workers.[12] In
this latter complex each CuIII ion has two weakly bound
6-methyl-2-pyridylmethyl side arms in the axial positions. Our
spectra also corresponded with other previous observa-
tions[9b, 10, 11, 13b, 18, 19] and are typical of the Cu2(m-O)2 core,
and gives support to the assumption that the brown solution
contained an intermediate species (3) having the same bis(m-
oxo) dimer structure (Scheme 2). However, we should
mention that while the above resonance Raman data suggest
the presence of the bis(m-O) core, they do not rule out the
formation of the peroxo species during the course of the
reaction.
In conclusion, the CuI complexes of ligands with pendent
aromatic rings exhibited different reactivities with O2 which
depended on the nature of the aromatic rings. The present
finding indicates that the vicinal noncoordinating indole ring
3860
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Angew. Chem. Int. Ed. 2001, 40, No. 20

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[2] a) K. Aoki, H. Yamazaki, J. Chem. Soc. Dalton Trans. 1987, 2017; b) H.
Masuda, O. Matsumo, A. Odani, O. Yamauchi, Nippon Kagaku Kaishi
1988, 783; c) H. Masuda, T. Sugimori, A. Odani, O. Yamauchi, Inorg.
Chim. Acta 1991, 73; d) T. Sugimori, K. Shibakawa, H. Masuda, A.
Odani, O. Yamauchi, Inorg. Chem. 1993, 32, 4951; e) F. Zhang, A.
Odani, H. Masuda, O. Yamauchi, Inorg. Chem. 1996, 35, 7148; f) T.
Sugimori, H. Masuda, N. Ohata, K. Koiwai, A. Odani, O. Yamauchi,
Inorg. Chem. 1997, 36, 576; g) O. Yamauchi, A. Odani, S. Hirota, Bull.
Chem. Soc. Jpn. 2001, in press.
containing the NH moiety, as compared with the phenyl and
naphthyl rings without it, may stabilize the bis(m-oxo)dicop-
per(iii) intermediate and affect subsequent reactions. Further
studies along this line are under way.
Experimental Section
Synthesis of BIP: Indole (2.34 g, 20 mmol), formalin (37%, 1.62 g,
20 mmol), and a few drops of acetic acid were added to a solution of
2-pyridylmethylamine (1.08 g, 10 mmol) in methanol (100 mL). The
reaction mixture was stirred overnight at room temperature and then
concentrated almost to dryness in vacuo. The residue was dissolved in a
saturated aqueous solution of NaHCO3 (50 mL) and extracted with CHCl3.
The white powder obtained from the extract was recrystallized from ethyl
acetate. Yield: 1.89 g (52%); 1H NMR (300 MHz, CDCl3): d ˆ 3.82 (s, 2H),
3.88 (s, 4H), 7.08 (dd, 1H), 7.09 (dt, 2H), 7.17 ± 7.19 (m, 4H), 7.34 (d, 2H),
7.54 ± 7.60 (m, 2H), 7.69 (d, 2H), 8.07 (brs, 2H), 8.48 (d, 1H).
[3] Y. Shimazaki, H. Yokoyama, O. Yamauchi, Angew. Chem. 1999, 111,
2561; Angew. Chem. Int. Ed. 1999, 38, 2401.
[4] a) W. S. Striejewske, R. R. Conry, Chem. Commun. 1998, 555; b) R. R.
Conry, W. S. Striejewske, A. A. Tipton, Inorg. Chem. 1999, 38, 2833.
[5] a) Active Oxygen in Biochemistry (Eds.: J. S. Valentine, C. S. Foote, A.
Greenberg, J. F. Liebman), Chapman & Hall, London, 1995; b) Active
Oxygen in Chemistry (Eds.: C. S. Foote, J. S. Valentine, A. Greenberg,
J. F. Liebman), Chapman & Hall, London, 1995.
Â
[6] a) K. D. Karlin, Z. Tyeklar, Adv. Inorg. Biochem. 1994, 9, 123; b) K. D.
Karlin, S. Kaderli, A. D. Zuberbühler, Acc. Res. Chem. 1997, 30, 139;
c) N. Kitajima, Adv. Inorg. Chem. 1992, 39, 1; d) N. Kitajima, Y. Moro-
oka, Chem. Rev. 1994, 94, 737; e) W. B. Tolman, Acc. Chem. Res. 1997,
30, 227.
Synthesis of BBP and BNP: BBP was prepared by the reaction of
dibenzylamine (1.97 g, 10 mmol) with 2-pyridinecarboxaldehyde (0.63 g,
10 mmol) in methanol and subsequent reduction by sodium cyanotrihy-
droborate (0.63 g, 10 mmol). Yield: 1.28 g (35%); 1H NMR (300 MHz,
CDCl3): d ˆ 3.62 (s, 4H), 3.74 (s, 2H), 7.12 (m, 1H), 7.23 (m, 2H), 7.31 (t,
2H), 7.32 (t, 2H), 7.41 (d, 4H), 7.64 (t, 2H), 7.66 (dt, 1H), 8.49 (d, 1H). BNP
Â
[7] a) R. R. Jacobson, Z. Tyeklar, A. Farooq, K. D. Karlin, S. Liu, J.
Â
Zubieta, J. Am. Chem. Soc. 1988, 110, 3690; b) Z. Tyeklar, R. R.
Jacobson, N. Wei, N. N. Murthy, J. Zubieta, K. D. Karlin, J. Am. Chem.
Soc. 1993, 115, 2677.
was prepared in
a similar way from 2-pyridylmethylamine (1.07 g,
10 mmol), 1-naphthaldehyde (3.12 g, 20 mmol), and sodium cyanotrihy-
droborate (1.26 g, 20 mmol). Yield: 3.32 g (87%); 1H NMR (300 MHz,
CDCl3): d ˆ 3.82 (s, 2H), 4.08 (s, 4H), 7.10 (m, 1H), 7.20 (m, 2H), 7.38 (t,
2H), 7.42 (t, 2H), 7.51 (t, 2H), 7.56 (d, 2H), 7.77 (d, 2H), 7.80 (d, 2H), 7.86
(d, 2H), 8.47 (d, 1H).
[8] a) N. Kitajima, K. Fujisawa, Y. Moro-oka, K. Toriumi, J. Am. Chem.
Soc. 1989, 111, 8975; b) N. Kitajima, K. Fujisawa, C. Fujimoto, Y.
Moro-oka, S. Hashimoto, T. Kitagawa, K. Toriumi, K. Tatsumi, A.
Nakamura, J. Am. Chem. Soc. 1992, 114, 1277; c) M. Kodera, K.
Katayama, Y. Tachi, K. Kano, S. Hirota, S. Fujinami, M. Suzuki, J. Am.
Chem. Soc. 1999, 121, 11006.
Synthesis of complexes: Complex 1 was prepared as pale yellow crystals
from BIP (0.366 g, 1.0 mmol) and CuI (0.190 g, 1.0 mmol) in acetone/
[9] a) J. A. Halfen, S. Mahapatra, E. C. Wilkinson, S. Kaderli, V. G.
Young, Jr., L. Que, Jr., A. D. Zuberbühler, W. B. Tolman, Science
1996, 271, 1397; b) S. Mahapatra, J. A. Halfen, E. C. Wilkinson, G.
Pan, X. Wang, V. G. Young, Jr., C. J. Cramer, L. Que, Jr., W. B.
Tolman, J. Am. Chem. Soc. 1996, 118, 11555; c) S. Mahapatra, J. A.
Halfen, W. B. Tolman, J. Am. Chem. Soc. 1996, 118, 11575; d) S.
Mahapatra, V. G. Young, Jr., S. Kaderli, A. D. Zuberbühler, W. B.
Tolman, Angew. Chem. 1997, 109, 125; Angew. Chem. Int. Ed. Engl.
1997, 36, 130; e) B. M. T. Lam, J. A. Halfen, V. G. Young, Jr., J. R.
CH3CN (4/1) under
a nitrogen atmosphere. Yield: 0.372 g (74%);
elemental analysis (%) calcd for 1 ´ 2CH3COCH3 (C54H56N8O2Cu2I2): C
52.73, H 4.59, N 9.11; found: C 52,68, H 4.47, N 8.95. [Cu(bbp)I] and
[Cu(bnp)I] were prepared in THF in a similar way. Elemental analysis (%)
calcd for [Cu(bbp)I] (C20H20N2CuI): C 50.17, H 4.21, N 5.85; found: C 50.11,
H 4.24, N 5.85. Elemental analysis (%) calcd for [Cu(bnp)I] (C28H24N2CuI):
C 58.09, H 4.18, N 4.84; found: C58.13, H 4.20, N 4.87. Complex 2 was
prepared as colorless crystals from Me-IMP[3] (0.205 g, 0.6 mmol),
[Cu(CH3CN)]ClO4 (0.164 g, 0.6 mmol), and sodium tetraphenylborate
(0.205 g, 0.6 mmol) in CH3OH under a CO atmosphere. Elemental analysis
(%) calcd for 2 (C47H42N4OBCu): C 74.95, H 5.62, N 7.44; found: C 75.59, H
5.60, N 7.41.
Ligand recovery:[14, 21] In a typical experiment, 1 (1.23 g, 1.0 mmol) was
dissolved in THF (20 mL) under a nitrogen atmosphere, and O2 was passed
through the solution for 10 min at 808C. The solution was kept standing
for one day at room temperature, and the resulting green solution was
evaporated to dryness in vacuo. The residue was dissolved in concentrated
NH3 (10 mL) and extracted with CHCl3 (3 Â 10 mL). The combined organic
fractions were dried over Na2SO4, filtered, and concentrated in vacuo to
leave a brown oil. The decomposition products 4 ± 6 were separated by
column chromatography on silica gel, and their structures and relative
amounts were determined by 1H NMR spectroscopy. Crystals of 6 suitable
for X-ray structure determination were prepared by recrystallization from
CHCl3. Elemental analysis (%) calcd for 6 ´ 1.5CHCl3 (C25.5H21.5N4OCl4.5):
C 54.74, H 3.87, N 10.01; found: C 54.44, H 3.99, N 9.70; 1H NMR
(300 MHz, CD3OD): d ˆ 3.02 (dd, 2H), 3.96 (dd, 2H), 3.98 (q, 2H), 4.12 (d,
1H), 6.97 (t, 3H), 7.03 (t, 1H), 7.19 (t, 2H), 7.27 (t, 1H), 7.35 (d, 1H), 7.39 (d,
1H), 7.67 ± 7.78 (m, 2H), 8.43 (d, 1H).
Â
Â
Hagadorn, P. L. Holland, A. Lledos, L. Cucurull-Sanchez, J. J. Novoa,
S. Alvarez, W. B. Tolman, Inorg. Chem. 2000, 39, 4059.
[10] V. Mahadevan, Z. Hou, A. P. Cole, D. E. Root, T. K. Lal, E. I.
Solomon, T. D. P. Stack, J. Am. Chem. Soc. 1997, 119, 11996.
[11] E. Pidcock, S. DeBeer, H. V. Obias, B. Hedman, K. O. Hodgson, K. D.
Karlin, E. I. Solomon, J. Am. Chem. Soc. 1999, 121, 1870.
[12] H. Hayashi, S. Fujinami, S. Nagatomo, S. Ogo, M. Suzuki, A. Uehara,
Y. Watanabe, T. Kitagawa, J. Am. Chem. Soc. 2000, 122, 2124.
[13] a) S. Itoh, H. Nakao, L. M. Berreau, T. Kondo, M. Komatsu, S.
Fukuzumi, J. Am. Chem. Soc. 1998, 120, 2890; b) S. Itoh, M. Taki, H.
Nakao, P. L. Holland, W. B. Tolman, L. Que, Jr., S. Fukuzumi, Angew.
Chem. 2000, 112, 409; Angew. Chem. Int. Ed. 2000, 39, 398.
[14] P. L. Holland, K. R. Rodgers, W. B. Tolman, Angew. Chem. 1999, 111,
1210; Angew. Chem. Int. Ed. 1999, 38, 1139.
[15] a) R. W. Cruse, S. Kaderli, K. D. Karlin, A. D. Zuberbühler, J. Am.
Chem. Soc. 1988, 110, 6882; b) M. S. Nasir, B. I. Cohen, K. D. Karlin, J.
Am. Chem. Soc. 1992, 114, 2482; c) K. D. Karlin, M. S. Nasir, B. I.
Cohen, R. W. Cruse, S. Kaderli, A. D. Zuberbühler, J. Am. Chem. Soc.
1994, 116, 1324.
[16] The X-ray experiments for complexes 1 and 3 were carried out on a
Rigaku RAXIS imaging plate area detector with graphite monochro-
mated MoKa radiation (l ˆ 0.71070 Š). The crystals were mounted on
a glass capillary tube. In order to determine the cell constant and
orientation matrix, three oscillation photographs were taken with an
oscillation angle of 28 and the exposure time of 8 min for each frame.
Intensity data were collected by taking oscillation photographs.
Refraction data were corrected for both Lorentz and polarization
effects. The unit-cell parameters used for the refinement were
determined by least-squares calculations on the setting angles for
25 reflections that were collected on a Rigaku AFC-5R four-circle
automated diffractometer. The measurement for 6 was carried out on
Received: March 21, 2001
Revised: August 2, 2001 [Z16822]
[1] a) D. van der Helm, C. E. Tatsch, Acta Crystallogr. Sect. B 1972, 28,
2307; b) M. B. Hursthouse, S. A. A. Jayaweera, H. Milburn, A. Quick,
J. Chem. Soc. Dalton Trans. 1975, 2569; c) H. Kozlowski, Inorg. Chim.
Acta 1978, 31, 135; d) P. I. Vestues, R. B. Martin, J. Am. Chem. Soc.
1980, 102, 7906.
Angew. Chem. Int. Ed. 2001, 40, No. 20
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a Rigaku AFC-5R four-circle automated diffractometer using a
rotating anode generator with graphite monochromated CuKa radia-
tion (l ˆ 1.54178 Š). The crystals were mounted on a glass capillary
tube. The reflection intensities for 6 were monitored by three standard
reflections at every 2 h and 150 measurements, and the decay of
intensities for the crystals was within 2%. Refraction data were
corrected for both Lorentz and polarization effects. 1: C54H56N8O2-
Cu2I2, pale yellow crystals, monoclinic, space group P21/n, a ˆ
Immobilization of p-Assembled Metallo-
Supramolecular Arrays in Thin Films: From
Crystal-Engineered Structures to Processable
Materials**
Henning Krass, Edward A. Plummer,
Johanna M. Haider, Philip R. Barker,
Nathaniel W. Alcock, Zoe Pikramenou,*
Michael J. Hannon,* and Dirk G. Kurth*
13.704(9),
b ˆ 8.349(2),
c ˆ 23.318(4) Š,
b ˆ 89.88(3)8,
Vˆ
2667(1) Š3, Z ˆ 4, 1calcd ˆ 1.531 gcm 3, R ˆ 0.081, Rw ˆ 0.141 for all
6345 reflections (I > 2.0s(I)) and 308 parameters. 2: C47H42N4OBCu,
colorless crystals, monoclinic, space group P21/n, a ˆ 11.5365(3), b ˆ
22.5800(5), c ˆ 15.8994(5) Š, b ˆ 107.8117(6)8, Vˆ 3934.2(2) Š3, Z ˆ
4, 1calcd ˆ 1.269 gcm 3, R ˆ 0.061, Rw ˆ 0.100 for all 7975 reflections
(I > 2.0s(I)) and 488 parameters. 6: C26H22N4OCl6, colorless crystals,
monoclinic, space group P21/c, a ˆ 10.743(3), b ˆ 17.820(4), c ˆ
Material and device performance is critically dependent on
the spatial arrangement of the functional constituents. The
ability to control the short- and long-range correlation of
position and orientation of components is crucial for full
exploitation of a materialꢁs potential and the encoding of new
properties.[1] Supramolecular synthetic methodologies enable
the systematic design and construction of tailored architec-
tures through a sequence of directed assembly processes.[2]
Metallo-units are particularly attractive functional compo-
nents because of their inherent magneto-,[3] electro-,[4] and/or
photochemical[5] properties.
By means of crystal engineering, solid-state multimetal
arrays can be constructed by using interactions of metal ions
with multitopic ligands[6] or other intermolecular forces to
organize metallo-units.[7±9] However, processing a crystalline
solid into a device remains a challenge. Moreover, in a single
crystal, it is difficult to achieve attractive features such as
gradients, often necessary for vectorial functions. Thin films
play an important role in applications[10] such as storage,
display, and sensing, yet to date there are no generic method-
ologies for incorporating and ordering discrete cationic metal
complexes into thin films.[11] To address this challenge and to
attempt to bridge the gap between fundamental supramolec-
ular crystal engineering and layered materials, we investigated
whether p-aggregated metallo-arrays can be incorporated
into ordered two-dimensional thin films.
15.673(3) Š,
b ˆ 105.72(2)8,
Vˆ 2887(1) Š3,
Z ˆ 4,
1calcd
ˆ
3
1.424 gcm
,
R ˆ 0.085, Rw ˆ 0.088 for all 4287 reflections (I >
2.0s(I)) and 335 parameters. Crystallographic data (excluding struc-
ture factors) for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication nos. CCDC-159430 ± 159432, for 1, 2, and
6. Copies of the data can be obtained free of charge on application to
CCDC, 12 Union Road, Cambridge CB21EZ, UK (fax: (‡44)1223-
336-033; e-mail: deposit@ccdc.cam.ac.uk).
[17] Spectral changes observed on oxygenation of 2 and [Cu(bnp)I] as well
as an ORTEP view of 6 can be found in the Supporting Information.
[18] P. L. Holland, C. J. Cramer, E. C. Wilkinson, S. Mahapatra, K. R.
Rodgers, S. Itoh, M. Taki, S. Fukuzumi, L. Que, Jr., W. B. Tolman, J.
Am. Chem. Soc. 2000, 122, 792.
[19] E. Pidcock, S. DeBeer, H. V. Obias, B. Hedman, K. O. Hodgson, K. D.
Karlin, E. I. Solomon, J. Am. Chem. Soc. 1999, 121, 1870.
[20] [Cu(bbp)I] was revealed to have the same dimeric structure as that of
1 by X-ray analysis (unpublished result), while the structure of
[Cu(bnp)I] is not established yet. Therefore, these complexes are
tentatively expressed as monomers.
[21] Y. Shimazaki, S. Huth, A. Odani, O. Yamauchi, Angew. Chem. 2000,
112, 1732; Angew. Chem. Int. Ed. 2000, 39, 1666.
A particularly attractive method to assemble thin films is
the layer-by-layer (LbL) method, which rests primarily on
[*] Dr. M. J. Hannon, E. A. Plummer, P. R. Barker, Dr. N. W. Alcock
Centre for Supramolecular and Macromolecular Chemistry
Department of Chemistry, University of Warwick
Coventry CV47AL (UK)
Fax : (‡44)2476-524-112
E-mail: m.j.hannon@warwick.ac.uk
Dr. D. G. Kurth, Dipl.-Chem. H. Krass
Max-Planck-Institute of Colloids and Interfaces
14424 Potsdam (Germany)
Fax : (‡49)331-567-9202
E-mail: kurth@mpikg-golm.mpg.de
Dr. Z. Pikramenou, Dr. J. M. Haider
School of Chemistry, University of Birmingham
Edgbaston B152TT (UK)
Fax : (‡44)121-414-4403
E-mail: z.pikramenou@bham.ac.uk
[**] We thank the Deutsche Forschungsgemeinschaft (H.K.), the Lever-
hulme Trust (J.M.H.), EPSRC (P.R.B), and the British ± German
Academic Research Collaboration Programme (British Council/
DAAD) for financial support of this research, the Swansea EPSRC
National Mass Spectrometry Service Centre for recording the mass
spectra, and Professor H. Möhwald for valuable discussions.
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