increased the ferromagnetic phase transition temperature T C , [431] the longer
molecular length of MePy-MC than that of MePy-SP increased T C .
The magnetism of LDHs depended on the dipole interactions between the LDH
layers which are smaller with longer interlayer distance [441]. A CoAl-LDH
(Co 0.69 Al 0.31 (OH) 2 (CO 3 ) 0.155 (H 2 O) 0.3 ) had spontaneous magnetization below the
critical temperature T M at 4.7 K [444]. T M of a CoAl-LDH (Co 0.65 Al 0.35 (OH) 2 )
was switched by the cis-trans photoisomerization of the intercalated
dicarboxylazobenzene (designated as AZCOO
À ) [436]. T M of the CoAl-LDH hybrid
(4.5 K) increased to 5.2 K by 355 nm UV irradiation accompanied by the basal
spacing change from 20.29 to 20.18 nm, suggesting that the change in the nanostructure was the reason of the increase of T M . The basal spacing did not revert to the
initial value by visible light irradiation in acetonitrile, while it reverted by exposure
of water under the visible light irradiation. As discussed in Sect. 5.3.1, vapor played
an important role in the change in the basal spacing [346]. It is thought that the
adsorption of the water molecules triggered the backward reaction to the initial
molecular packing.
Magnetism of alkylcarboxylate intercalated layered Co and Cu hydroxides
(Co 7 (OH) 11.6 and Cu 2 (OH) 2 ) depended on the length and π-conjugate system of
the alkylcarboxylate surfactants due to the interlayer ferromagnetic interaction
[445]. The photocyclization of diarylethene, which accompanies the switching of
the π-conjugate system, affected the magnetic interactions of two nitronyl nitroxide
moieties substituted to the phenylthiophene moieties of the diarylethene
[446, 447]. T C of a hybrid of a layered Co 4 (OH) 7 (designated as Co-LDH) intercalated an open-ring isomer of SO 3 DAE in Scheme 17 was 9 K, while that after UV
irradiation increased to 20 K [439]. Although the mechanism was not reported in
detail [438, 440], the photoswitch of the π-conjugate system of the intercalated
SO 3 DAE seemed to affect the magnetism of Co-LDH [446, 447].
The photoswitching of the π-conjugate system by the photocyclization and the
photoswitching of the basal spacing caused by photochromism affected to the
magnetism of the LDHs. As discussed in Sects. 5.2.2 and 5.3.1, the design of the
hybrids and the photoinduced adsorption of vapor are expected to make these
phenomena effective, suggesting that the elucidation and improvement of the photoinduced phenomena of the hybrids induce the effective magnetism switching.
5.3.4 Photoinduced Adsorption
As discussed in Sect. 5.3.1, adsorption of vapor during the photochromic changes
induced the change in the basal spacing [346]. Adsorption of phenol onto organically
modified clay from an aqueous solution was also reported [101, 282, 448, 449]. Motivated by the phenomena, photoinduced adsorption of phenol was examined
[166, 167, 344]. AZC 2 N
+
C 2 OH and C 2 AZC 2 N
+ (Table 3) intercalated KF were
mixed with neat phenol. As shown in Fig. 18, gallery heights increased from 0.81 to
1.5 nm and 0.96 to 2.6 nm by mixing with phenol, respectively [344]. The gallery
heights of the hybrids AZC 2 N
+
C 2 OH-KF with phenol increased further from 1.5 to
292
T. Yamaguchi et al.
molecular length of MePy-MC than that of MePy-SP increased T C .
The magnetism of LDHs depended on the dipole interactions between the LDH
layers which are smaller with longer interlayer distance [441]. A CoAl-LDH
(Co 0.69 Al 0.31 (OH) 2 (CO 3 ) 0.155 (H 2 O) 0.3 ) had spontaneous magnetization below the
critical temperature T M at 4.7 K [444]. T M of a CoAl-LDH (Co 0.65 Al 0.35 (OH) 2 )
was switched by the cis-trans photoisomerization of the intercalated
dicarboxylazobenzene (designated as AZCOO
À ) [436]. T M of the CoAl-LDH hybrid
(4.5 K) increased to 5.2 K by 355 nm UV irradiation accompanied by the basal
spacing change from 20.29 to 20.18 nm, suggesting that the change in the nanostructure was the reason of the increase of T M . The basal spacing did not revert to the
initial value by visible light irradiation in acetonitrile, while it reverted by exposure
of water under the visible light irradiation. As discussed in Sect. 5.3.1, vapor played
an important role in the change in the basal spacing [346]. It is thought that the
adsorption of the water molecules triggered the backward reaction to the initial
molecular packing.
Magnetism of alkylcarboxylate intercalated layered Co and Cu hydroxides
(Co 7 (OH) 11.6 and Cu 2 (OH) 2 ) depended on the length and π-conjugate system of
the alkylcarboxylate surfactants due to the interlayer ferromagnetic interaction
[445]. The photocyclization of diarylethene, which accompanies the switching of
the π-conjugate system, affected the magnetic interactions of two nitronyl nitroxide
moieties substituted to the phenylthiophene moieties of the diarylethene
[446, 447]. T C of a hybrid of a layered Co 4 (OH) 7 (designated as Co-LDH) intercalated an open-ring isomer of SO 3 DAE in Scheme 17 was 9 K, while that after UV
irradiation increased to 20 K [439]. Although the mechanism was not reported in
detail [438, 440], the photoswitch of the π-conjugate system of the intercalated
SO 3 DAE seemed to affect the magnetism of Co-LDH [446, 447].
The photoswitching of the π-conjugate system by the photocyclization and the
photoswitching of the basal spacing caused by photochromism affected to the
magnetism of the LDHs. As discussed in Sects. 5.2.2 and 5.3.1, the design of the
hybrids and the photoinduced adsorption of vapor are expected to make these
phenomena effective, suggesting that the elucidation and improvement of the photoinduced phenomena of the hybrids induce the effective magnetism switching.
5.3.4 Photoinduced Adsorption
As discussed in Sect. 5.3.1, adsorption of vapor during the photochromic changes
induced the change in the basal spacing [346]. Adsorption of phenol onto organically
modified clay from an aqueous solution was also reported [101, 282, 448, 449]. Motivated by the phenomena, photoinduced adsorption of phenol was examined
[166, 167, 344]. AZC 2 N
+
C 2 OH and C 2 AZC 2 N
+ (Table 3) intercalated KF were
mixed with neat phenol. As shown in Fig. 18, gallery heights increased from 0.81 to
1.5 nm and 0.96 to 2.6 nm by mixing with phenol, respectively [344]. The gallery
heights of the hybrids AZC 2 N
+
C 2 OH-KF with phenol increased further from 1.5 to
292
T. Yamaguchi et al.