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‘Ionic crystals’ consisting of trinuclear macrocations and polyoxometalate anions exhibiting single crystal to single crystal transformation: breathing of crystals
Ion pairing of trinuclear macrocation cluster (known as basic carboxylate), [ M 3 ( μ 3 -O) ( ClCH 2 COO ) 6 ( H 2 O ) 3 ] 1 + and a Keggin type polyoxometalate cluster anion [ SiW 12 O 40 ] 4 - is stabilized with a number of crystal water molecules in composite type compounds [ M 3 ( μ 3 -O) ( ClCH...
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| Published in: | Journal of chemical sciences (Bangalore, India) India), 2017-08, Vol.129 (8), p.1121-1142 |
|---|---|
| Main Authors: | , , |
| Format: | Article |
| Language: | English |
| Subjects: | |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Ion pairing of trinuclear macrocation cluster (known as basic carboxylate), [
M
3
(
μ
3
-O)
(
ClCH
2
COO
)
6
(
H
2
O
)
3
]
1
+
and a Keggin type polyoxometalate cluster anion
[
SiW
12
O
40
]
4
-
is stabilized with a number of crystal water molecules in composite type compounds [
M
3
(
μ
3
-O)
(
ClCH
2
COO
)
6
(
H
2
O
)
3
]
4
[
SiW
12
O
40
]
·
xH
2
O
·
2ClCH
2
COOH
[
M
=
Fe
3
+
,
x
=
18
(
1
)
;
M
=
Cr
3
+
x
=
14
(
2
)
]. When the crystals of
1
are heated at 85
∘
C and 135
∘
C for 3.5 hours in an open atmospheric condition, it goes to [
Fe
3
(
μ
3
-O)
(
ClCH
2
COO
)
6
(
H
2
O
)
3
]
4
[
SiW
12
O
40
]
·
10
H
2
O
·
2ClCH
2
COOH (
dehydrated
1
-
85
o
≡
1
′
), and [
Fe
3
(
μ
3
-O)(
ClCH
2
COO
)
6
(
H
2
O
)
3
]
4
[
SiW
12
O
40
]
·
8
H
2
O
·
2
ClCH
2
COOH (
dehydrated 1
-
135
o
≡
1
″
) respectively with the loss of considerable amount of lattice water molecules retaining their single crystallinity. On the other hand, the single crystals of compound
2
, upon heating at 85
∘
C or 135
∘
C for 3.5 hours, undergo ‘crystal-to-crystal transformation’ to the single crystals of [
Cr
3
(
μ
3
-O)(
ClCH
2
COO
)
6
(
H
2
O
)
3
]
4
[
SiW
12
O
40
]
·
8
H
2
O
·
2
ClCH
2
COOH (
dehydrated
2
≡
2
′
). Crystal structure analyses show that the parent compounds
1
and
2
undergo molecular rearrangement (molecular motion in the solid state) in respective dehydrated compounds. Remarkably, these dehydrated crystals (
1
′
,
1
″
and
2
′
), upon exposure to water vapor at an ambient condition, regenerate the crystals of parent compounds
1
and
2
, respectively.
Graphical Abstract:
Breathing of crystal:
The unit cell volume (17106 Å
3
)
of [
Fe
3
(
μ
3
-O)(
ClCH
2
COO
)
6
(
H
2
O
)
3
]
4
[
SiW
12
O
40
]
·
18
H
2
O
·
2
ClCH
2
COOH (
1
) shrinks on heating
1
at 85
∘
C to produce the reduced unit cell volume (15084 Å
3
) of [
Fe
3
(
μ
3
-O)(
ClCH
2
COO
)
6
(
H
2
O
)
3
]
4
[
SiW
12
O
40
]
·
10
H
2
O
·
2
ClCH
2
COOH (
dehydrated 1
-
85
o
), represented as (a)
→
(b). This can be reversed, (b)
→
(a), in the solid state on re-hydration of
dehydrated 1
-
85
o
resulting in the formation of parent
1
. |
|---|---|
| ISSN: | 0974-3626 0973-7103 |
| DOI: | 10.1007/s12039-017-1324-0 |