Flexible decapyrrylcorannulene hosts

Abstract

The assembly of spherical fullerenes, or buckyballs, into single crystals for crystallographic identification often suffers from disordered arrangement. Here we show a chiral configuration of decapyrrylcorannulene that has a concave ‘palm’ of corannulene and ten flexible electron-rich pyrryl group ‘fingers’ to mimic the smart molecular ‘hands’ for self-adaptably cradling various buckyballs in a (+)hand-ball-hand(−) mode. As exemplified by crystallographic identification of 15 buckyball structures representing pristine, exohedral, endohedral, dimeric and hetero-derivatization, the pyrryl groups twist with varying dihedral angles to adjust the interaction between decapyrrylcorannulene and fullerene. The self-adaptable electron-rich pyrryl groups, susceptible to methylation, are theoretically revealed to contribute more than the bowl-shaped palm of the corannulene in holding buckyball structures. The generality of the present decapyrrylcorannulene host with flexible pyrryl groups facilitates the visualization of numerous unknown/unsolved fullerenes by crystallography and the assembly of the otherwise close-packed spherical fullerenes into two-dimensional layered structures by intercalation.

Magnetization-governed magnetoresistance anisotropy in the topological semimetal CeBi

“…That is, the MR and its anisotropy in CeSb and CeBi at low temperatures, particularly in high magnetic fields may have similar origins. For example, the dips in R(q) curves presented in Fig.S3 for H ∥ <011> and T = 3 K originate most likely from magnetization-flops, similar to those in CeSb [50]. However, Fig.S7 also discloses significant differences of CeBi's MR behavior from that of CeSb.…”

“…Recently, Xu et al [50] investigated the MR anisotropy of CeSb, which is a sister cerium monopnictide of CeBi, in the low temperature high magnetic-field driven ferromagnetic state.…”

“…Due to strong p-f mixing, CeSb has a strong magnetic anisotropy with the easy axis along <001> [46]. The magnetization is induced only by the component of the magnetic field along <001>, resulting in a 1/cosj dependence of the magnetic field values HFM above which the material is in the ferromagnetic phase [50,53], where the relationship of to the angle q defined in the inset of Fig.2 is = q -np/2 with n = 0, 1, 2, 3, and 4 for 0°…”

“…£ q £ 315°, and 315° £ q £ 360°, respectively [50]. In Fig.S6a we present the R(H) curve obtained at T = 3 K and q = 45°, from which HFM can be derived.…”

“…However, Fig.S7 also discloses significant differences of CeBi's MR behavior from that of CeSb. For example, at the ferromagnetic transition, CeSb has lower resistances in the ferromagnetic phase for all field orientations [50,51]. The R(H) curves of CeBi show only a slight downturn kink at q = 0° or an upturn bump at q = 90° (insets in Fig.S7).…”