Enantiomeric Hydrogen-bonded Chains Driving Ferroelectric and Nonlinear Optical Behavior
Nan Zhang, Yao Zhang, Huan‐Huan Jiang, Guo‐Wei Du, Qiang Pan, Ren‐Gen Xiong, Han‐Yue Zhang
Abstract
Organic multiferroic materials have been widely investigated due to their novel physical properties and broad applications. However, the discovery of organic small-molecular multiferroic compounds is still rare. Herein, based on the chemical design strategy of introducing homochirality, we present a pair of enantiomeric organic small-molecular compounds [HDABCO (1,4-diazabicyclo[2.2.2]octonium)][l- and d-MA (malic acid)], which displays high Curie temperatures (Tc) of 409/412 K, superior optoelectronic performance, and unique ferroelectric and ferroelastic nature. In comparison with the reported ferroelectrics with the [HDABCO]+ cation chain structure, the enantiomers show a neutral one-dimensional chain, where hydrogen bonds connect [HDABCO]+ cations and [MA]− anions. Strikingly, [HDABCO][l- and d-MA] exhibit a large second harmonic generation (SHG) intensity of about 2.46 and 2.53 times that of KH2PO4 (KDP), exceeding those of all the organic ferroelectrics (about 0.2–1 × KDP). With excellent SHG signal and ferroic properties, as well as the merit of low acoustic impedance z0 matching that of the body and easy processing, [HDABCO][l- and d-MA] are potential candidates for future biocompatible electronic devices with multi-functionality.