Volume 2021, Issue 6 p. 990-997
Full Paper

Molecular Recognition by Chalcogen Bond: Selective Charge-Transfer Crystal Formation of Dimethylnaphthalene with Selenadiazolotetracyanonaphthoquinodimethane

Dr. Yusuke Ishigaki

Dr. Yusuke Ishigaki

Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan

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Kota Asai

Kota Asai

Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan

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Dr. Henri-Pierre Jacquot de Rouville

Dr. Henri-Pierre Jacquot de Rouville

Institut de Chimie de Strasbourg, CNRS UMR 7177, Université de Strasbourg, 4, rue Blaise Pascal, 67000 Strasbourg, France

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Takuya Shimajiri

Takuya Shimajiri

Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan

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Prof. Dr. Valérie Heitz

Prof. Dr. Valérie Heitz

Institut de Chimie de Strasbourg, CNRS UMR 7177, Université de Strasbourg, 4, rue Blaise Pascal, 67000 Strasbourg, France

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Dr. Hiroshi Fujii-Shinomiya

Dr. Hiroshi Fujii-Shinomiya

Department of Chemistry, Faculty of Science, Tohoku University, Sendai, 980-8578 Japan

On leave from Mitsubishi Oil Company, Co. Ltd.

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Prof. Dr. Takanori Suzuki

Corresponding Author

Prof. Dr. Takanori Suzuki

Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan

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First published: 10 December 2020
Citations: 9

In memory of François Diederich and Tsutomu Miyashi.

Graphical Abstract

Highly selective cocrystallization with 2,6-dimethylnaphthalene (2,6-DMN) allows the title selenadiazole-based electron acceptor to separate 2,6-DMN from the isomer mixture by an effective Se⋅⋅⋅N chalcogen bond whereas the sulfur congener shows only low selectivity due to the competing C−H⋅⋅⋅N hydrogen bond, which overwhelms the S⋅⋅⋅N bond.

Abstract

The title nonplanar electron acceptor (1) fused with a selenadiazole ring selectively forms a crystalline charge-transfer complex (CT crystal) with 2,6-dimethylnaphthalene (2,6-DMN). On the other hand, the sulfur analogue (2) has less recognition ability and forms CT crystals with both 2,6- and 2,7-DMN. X-ray analyses of 1, 2, and their CT crystals revealed that the Se⋅⋅⋅N chalcogen bond (ChB) in 1 is strong enough to determine the crystal packing with the formation of a cavity suitable for 2,6-DMN. On the contrary, ChB through S⋅⋅⋅N contact in 2 competes with other weak interactions such as a C−H⋅⋅⋅N hydrogen bond. The stronger ChB involving Se is the key for 1 to separate 2,6-DMN (>97 wt %) from a complex isomer mixture containing ca. 10 wt % each of 2,6- and 2,7-DMN by a simple, efficient and straightforward mixing-filtration-heating process.

Conflict of interest

The authors declare no conflict of interest.