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Detailed Investigation of the Structural, Thermal, and Electronic Properties of Gold Isocyanide Complexes with Mechano-Triggered Single-Crystal-to-Single-Crystal Phase Transitions

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Title: Detailed Investigation of the Structural, Thermal, and Electronic Properties of Gold Isocyanide Complexes with Mechano-Triggered Single-Crystal-to-Single-Crystal Phase Transitions
Authors: Seki, Tomohiro Browse this author →KAKEN DB
Sakurada, Kenta Browse this author
Muromoto, Mai Browse this author
Seki, Shu Browse this author
Ito, Hajime Browse this author →KAKEN DB
Keywords: gold complexes
metal-metal interactions
phase transitions
photoluminescence
single crystal
Issue Date: 6-Feb-2016
Publisher: Wiley-Blackwell
Journal Title: Chemistry-A European journal
Volume: 22
Issue: 6
Start Page: 1968
End Page: 1978
Publisher DOI: 10.1002/chem.201503721
PMID: 26751252
Abstract: Mechano-induced phase transitions in organic crystalline materials, which can alter their properties, have received much attention. However, most mechano-responsive molecular crystals exhibit crystal-to-amorphous phase transitions, and the intermolecular interaction patterns in the daughter phase are difficult to characterize. We have investigated phenyl(phenylisocyanide)gold(I) (1) and phenyl(3,5-dimethylphenylisocyanide)gold(I) (2) complexes, which exhibit a mechano-triggered single-crystal-to-single-crystal phase transition. Previous reports of complexes 1 and 2 have focused on the relationships between the crystalline structures and photoluminescence properties; in this work we have focused on other aspects. The face index measurements of complexes 1 and 2 before and after the mechano-induced phase transitions have indicated that they undergo non-epitaxial phase transitions without a rigorous orientational relationship between the mother and daughter phases. Differential scanning calorimetry analyses revealed the phase transition of complex 1 to be enthalpically driven by the formation of new aurophilic interactions. In contrast, the phase transition of complex 2 was found to be entropically driven, with the closure of an empty void in the mother phase. Scanning electron microscopy observation showed that the degree of the charging effect of both complexes 1 and 2 was changed by the phase transitions, which suggests that the formation of the aurophilic interactions affords more effective conductive pathways. Moreover, flash-photolysis time-resolved microwave conductivity measurements revealed that complex 1 increased in conductivity after the phase change, whereas the conductivity of complex 2 decreased. These contrasting results were explained by the different patterns in the aurophilic interactions. Finally, an intriguing disappearing polymorphism of complex 2 has been reported, in which a polymorph form could not be obtained again after some period of time, even with repeated trials. The present studies provide us with a variety of hitherto unknown insights into mechano-responsive molecular crystals, which help us to understand the phase transition behaviors upon mechanical stimulation and establish rational design principles.
Rights: "This is the peer reviewed version of the following article: Chemistry A European journal, 22(6) February 2016 Pages 1968-1978, which has been published in final form at [Link to final article using the 10.1002/chem.201503721. This article may be used for non-commercial purposes in accordance With Wiley-VCH Terms and Conditions for self-archiving".
Type: article (author version)
URI: http://hdl.handle.net/2115/64466
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 関 朋宏

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