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after thermal removal of the vapor molecules to form the
vapor-free phases, 1Rꢀopen and 2Rꢀopen, respectively,
although the color/luminescence changes because of changes
to the intermolecular metallophilic interactions. These vapor-
free phases collapse as a result of manual grinding in a mortar
to regenerate the initial purple amorphous forms, 1P and 2P.
CH
3
COOH vapor into the MeOH/water solution gave red crystals of
1
Rꢀwater that were suitable for X-ray diffraction analysis.
Preparation of vapor-exposed samples: The small amount of the
sample (ca. 2 mg) was added to a small glass vial and the vial was
placed in a larger, capped, glass vial with a small amount of liquid
(
ca. 1 mL) as the vapor source (see Figure S14 in the Supporting
Information). The glass vial was left in a temperature-controlled
incubator at 303 K for several days.
The temperature dependence of the luminescence spectra of
3
1
R indicates that the luminescence of 1R is due to MMLCT
Powder X-ray diffraction: Powder X-ray diffraction was conducted
with either a Rigaku SPD diffractometer at beamline BL-8B at the
Photon Factory, KEK, Japan or a Bruker D8 Advance diffractometer
equipped with a graphite monochromator using CuKa radiation
and a one-dimensional LinxEye detector. The wavelength of the
synchrotron X-rays was 1.5385(1) .
emission, similar to that of 2R. However, the weaker tempera-
ture dependence of 1R may be due to enhanced intermolecu-
lar p–p stacking interactions caused by the more expanded p
conjugation of the H dcphen ligand compared with that of
2
that the H dcbpy ligand, which would compete with the inter-
2
molecular Pt···Pt interactions. These results clearly indicate that
Luminescence properties: The luminescence spectra of the com-
plexes were measured with a JASCO FP-6600 spectrofluorometer
at room temperature. The typical slit widths of the excitation and
emission light were 5 and 6 nm, respectively. Temperature-depen-
dent luminescence spectra were measured with a Hamamatsu
multichannel photodetector (PMA-11) and a nitrogen laser for the
II
Pt –diimine supramolecular systems, such as 1 and 2, are not
only multichromic materials that respond to various external
stimuli, but also a new type of vapor-history sensing materials
with ON–OFF switching functions based on the shape-memory
ability derived from the formation and collapse of the porous
structure by vapor adsorption and manual grinding, respec-
tively. Further studies on molecule-based shape-memory
behavior are currently in progress.
3
37 nm excitation. A liquid nitrogen cryostat (Optistat-DN optical
Dewar and ITC-503 temperature controller, Oxford Instruments)
was used for temperature control.
Vapor-adsorption isotherms: Vapor-adsorption isotherms of the
complexes were measured using BELSORP-max vapor adsorption
isotherm measurement equipment at 298 K.
Single-crystal X-ray diffraction measurements: All the measure-
ments of 1Rꢀwater were conducted with a Rigaku AFC-11 diffrac-
tometer with a Mercury CCD area detector at beamline PF-AR
NW2A at the Photon Factory, KEK, Japan. The wavelength of the
synchrotron X-rays was 0.6890(1) . Temperature-dependent meas-
urements of 2Rꢀwater were conducted with a Rigaku Mercury
Experimental Section
General procedures: All commercially available starting materials
[
8]
were used without purification. The starting material Pt(CN)2, the
amorphous purple form of the bipyridyl complex
(2P)), and the red crystalline solid of
Pt(CN) (H dcbpy)]·3H O (2Rꢀwater) were prepared according to
[8]
(
[
[Pt(CN) (H dcbpy)]
2 2
CCD diffractometer with monochromated Mo radiation (l=
Ka
2
2
2
0
.71069 ) and a sealed X-ray tube generator. All single crystals
previously published methods. H dcphen was synthesized from
2
15]
were mounted on a MicroMount coated with paraffin oil. The crys-
[
4
,7-diformyl-1,10-phenanthroline,
and the final oxidation step
tal was then cooled by using an N flowtype temperature control-
2
was conducted according to the synthetic procedure of 2,2’:6’,2’’-
terpyridine-4’-carboxylic acid by using AgNO3.
the samples were measured on a JEOL EX-270 NMR spectrometer
at room temperature. Elemental analysis was conducted at the
Analysis Center at Hokkaido University.
ler. The diffraction data were collected and processed with Crystal-
[16] 1
H NMR spectra of
[17]
Clear software.
The structures were solved with the direct
[18]
method by using SIR-2004. Structural refinements were conduct-
ed by the full-matrix least-squares method with SHELXL-97. Non-
[19]
hydrogen atoms were refined anisotropically, and all hydrogen
atoms were refined with the riding model. All calculations were
conducted with the Crystal Structure crystallographic software
Synthesis of purple [Pt(CN) (H dcphen)] (1P): The yellowish green
2
2
Pt(CN) powder (273 mg, 1.1 mmol) was first suspended in aqueous
2
[20]
NH (25 mL) followed by addition of the white H dcphen powder
3
2
package. The crystallographic data for 1Rꢀwater is summarized
in Table S1 in the Supporting Information and is compared with
those of 2Rꢀwater. CCDC 1411618, 1415892, 1415893, 1415894,
(
134 mg, 0.5 mmol). The reaction mixture was refluxed at 110 8C for
one day. After cooling to room temperature, aqueous NH (30 mL)
3
was added to the reaction mixture, which was then refluxed for an
additional day. After cooling to room temperature, the resultant
yellowish green suspension was collected by filtration. Dilute aque-
ous HCl (5 mL) was added to the obtained yellow filtrate to pro-
mote precipitation of a purple solid, which was collected by centri-
fugation. The purple solid was suspended in 3% aqueous HCl
1
1
415895, 1415896 for complex 1, 1415897, 1415898, 1415899,
415900, 1415901 and 1415902 for complex 2 contain the supple-
(
200 mL), and the mixture was heated to 1008C for 10 min. The in-
soluble precipitates were immediately collected though filtration Acknowledgements
and dried in vacuum to give the desired product in the amorphous
1
purple form (1P). Yield: 139 mg, 50%. H NMR (4% NaOD in D O):
2
This work is supported by JST-PRESTO, Grant-in-Aid for Scien-
tific Research on Innovative Area “Artificial Photosynthesis”
d=9.08 (d, 2H), 8.36 (s, 2H), 7.95 ppm (d, 2H); elemental analysis
calcd (%) for C H N O Pt·2H O : C 35.85, H 2.19, N 10.16; found:
1
6
8
4
4
2
(
No. 2406), (B)(23350025) and (C)(26410063) from MEXT, Japan.
C 35.93, H 2.04, N 10.45.
Red crystalline solid of [Pt(CN) (H dcphen)]·3H O (1Rꢀwater):
2
2
2
The purple amorphous solid 1P (10.6 mg, 0.02 mmol) was dis-
solved in MeOH (1 mL) containing MeOLi/MeOH (120 mL, 10% solu-
Keywords: chromophores · mechanochromism · platinum ·
shape-memory effects · vapochromism
tion). H O (1.3 mL) was then added to this solution. Diffusion of
2
Chem. Eur. J. 2016, 22, 2682 – 2690
2689
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim