Anomalously rotary polarization discovered in homochiral organic ferroelectrics

Abstract

Molecular ferroelectrics are currently an active research topic in the field of ferroelectric materials. As complements or alternatives of conventional inorganic ferroelectrics, they have been designed to realize various novel properties, ranging from multiferroicity and semiconductive ferroelectricity to ferroelectric photovoltaics and ferroelectric luminescence. The stabilizing of ferroelectricity in various systems is owing to the flexible tailorability of the organic components. Here we describe the construction of optically active molecular ferroelectrics by introducing homochiral molecules as polar groups. We find that the ferroelectricity in (R)-(−)-3-hydroxlyquinuclidinium halides is due to the alignment of the homochiral molecules. We observe that both the specific optical rotation and rotatory direction change upon paraelectric-ferroelectric phase transitions, due to the existence of two origins from the molecular chirality and spatial arrangement, whose contributions vary upon the transitions. The optical rotation switching effect may find applications in electro-optical elements.

Room temperature magnetoelectric coupling in a molecular ferroelectric ytterbium(III) complex

“…These two complexes exhibit differences in the crystallographic distances and geometries (Tables S1-S2) that gives rise to uncompensated dipolar moments along the b axis. We confirmed this by analyzing the ions' location in the unit cell (Table S3) (29)(30)(31). We corroborated the enantiomeric nature of R,R-1 and S,S-2 using solid state circular dichroism (CD) ( Fig.…”

“…We determined a maximum local longitudinal piezoelectric coefficient at room temperature, which corresponded to a polarization of the order of magnitude of 10 µC.cm 2 . The theoretical spontaneous polarization which we estimated from the point charge model (29)(30)(31) along the b axis by considering only the metal ions and some ligand's atoms (Zn 2+ , Yb 3+ , O  and N + ) gives 3.32 µC.cm  ² along the [0 ] direction (see Table S3 (32)).…”

Organic enantiomeric high- T c ferroelectrics

“…3B and SI Appendix, Fig. S5B) and large thermal hysteresis, similar to those observed in (R)-3-hydroxlyquinuclidinium halides which undergo plastic transitions (38). Because of the plastic characteristics, it is difficult to determine the single-crystal structure of the high-temperature phase (HTP) above T c .…”

“…For nearly 100 y, homochiral ferroelectrics were basically multicomponent simple organic anime salts and metal coordination compounds, such as bis(imidazolium) L-tartrate and (R)-(-)-3-hydroxlyquinuclidinium halides (37)(38)(39), seignette salt (NaKC 4 H 4 O 6 ·4H 2 O) (22), (3-ammoniopyrrolidinium)NH 4 Br 3 , and (3-ammonioquinuclidinium)NH 4 Br 3 in our previous report (29). Single-component homochiral organic ferroelectric crystals are very rarely reported, although some single-component organic ferroelectrics without Curie temperature (T c ) were found (40).…”

H/F substitution for advanced molecular ferroelectrics

“…Ferroelectrochemistry, conceptually employing chemical ideas and approaches to design molecular ferroelectrics as well as optimize their performance, has been widely accepted, including the methodologies of reducing molecular symmetry, introducing homochirality, and H/F substitution [8,15,[17][18][19][20][21]. Among them, H/F substitution, which refers to the substitution of an F atom for an H atom, plays an important role in the chemical design of high-performance molecular ferroelectrics as well as their ferroelectric and piezoelectric performance optimization (Figure 1).…”