Organic Conductor Based on Nucleobase: Structural and Electronic Properties of a Charge-Transfer Solid Composed of TCNQ Anion Radical and Hemiprotonated Cytosine

Abstract

A semiconductive charge-transfer solid was prepared by the reaction of cytosine and TCNQ. Cytosine molecules formed a hemiprotonated cytosine pair by complementary triple hydrogen bonds, and the pairs were then linked by complementary double hydrogen bonds to form infinite ribbons. TCNQ molecules formed uniform segregated columns. The robust hydrogen bonds linking the cytosine and TCNQ molecules preserved the uniform arrangement even at low temperatures. Such structural regulation demonstrated a high conductivity of 3 × 10⁻² S cm⁻¹ in a fully ionic TCNQ salt by virtue of large transfer interaction and short interplanar distance of TCNQ molecules.

Keywords:

• charge-transfer conductor
• complementary hydrogen bond
• cytosine
• Nucleobase
• TCNQ

ACKNOWLEDGMENTS

This work was supported in part by a Grant-in-Aid (21st Century COE programs on Kyoto University Alliance for Chemistry and No. 15205019) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan. T. M. is a recipient of research fellowships from the Japan Society for the Promotion of Science (JSPS).