2007 Fiscal Year Final Research Report Summary
Investigation of metal complex channels that reversibly open and close responding to external stimuli
| Project/Area Number |
17550054
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | Shizuoka University |
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Principal Investigator |
KONDO Mitsuru Shizuoka University, Center for Instrumental Analysis, Associate Professor (80254142)
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| Project Period (FY) |
2005 – 2007
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| Keywords | hydrogen bonded network / dynamic property / single crystal structure / supramolecule / channel structure / solid structure / chemical stimuli / physical stimuli |
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| Research Abstract |
This project studies the effects of kinds of guest moleulcs G on the dynamic property of a new nickel complex [Ni(dps)_2(NO_3)_2]G (dps = dipyridylsulfide), which shows reversible channel structure changes, in which the G can be replaced by various primary alcohols, linear diols, and acetone. When n-propanol (PrOH) and methoxyethanol (MeOEtOH) are used as guest molecules G, decrease of the phase transition temperature due to the increase of molecular weight is observed. Single crystal X-ray analysis and differential scanning calorimetry (DSC) measurement demonstrated that [Ni(dps)_2(NO_3)_2]G changes channel structures due to the rotation of nitrate anions, diminishing the channel windows below critical temperature (ca. -5℃〜-20℃). This dynamic property contributes mechanical captures of guest molecules at the low temperature.
In addition to the physical stimuli, the control of channel structure by chemical stimuli was studied by using polymeric metal complexes constructed by hydrogen bonded networks. A new nickel complex [Ni(ima)_2(MeOH)_2](1) (ima = 4-imidazole acetate and the dried complex [Ni(ima)_2] (2) were prepared for this purpose. The dried complex 2 was obtained from Complex 1 on heating under reduced pressure. Complex 1 has hexagonal one-dimensional channels whose frameworks are supported by intermolecular NH …O=C hydrogen bonds. On the other hand, Complex 2 is amorphous. Contact of Complex 2 with methanol re-produces a crystalline Complex 1. Particularly, adsorption of other small molecules was observed as a result of re-productions of the one-dimensional channels. We have also clarified that the amorphous 2 is useful starting material for synthesis of new metal complexes that have network structures with flexible intermolecular hydrogen bonds.
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