Chiral Single Crystals Research Articles

Fused-Ring Electron-Acceptor Single Crystals with Chiral 2D Supramolecular Organization for Anisotropic Chiral Optoelectronic Devices.

Supramolecular chiral organization gives π-conjugated molecules access to fascinating specific interactions with circularly polarized light (CPL). Such a feature enables the fabrication of high-performance chiral organic electronic devices that detect or emit CPL directly. Herein, it is shown that chiral fused-ring electron-acceptor BTP-4F single-crystal-based phototransistors demonstrate distinguished CPL discrimination capability with current dissymmetry factor exceeding 1.4, one of the highest values among state-of-the-art direct CPL detectors. Theoretical calculations prove that the chirality at the supramolecular level in these enantiomeric single crystals originates from chiral exciton coupling of a unique quasi-2Dsupramolecular organization consisting of interlaced molecules with opposite helical conformation. Impressively, such supramolecular organization produces a higher dissymmetry factor along the preferred growth direction of the chiral single crystals in comparison to that of the short axis direction. Furthermore, the amplified, inverted, and also anisotropic current dissymmetry compared to optical dissymmetry is studied by finite element simulations. Therefore, a unique chiral supramolecular organization that is responsible for the excellent chiroptical response and anisotropic electronic properties is developed, which not only enables the construction of high-performance CPL detection devices but also allows a better understanding of the structure-property relationships in chiral organic optoelectronics.

Surface-Doped Quasi-2D Chiral Organic Single Crystals for Chiroptical Sensing.

Chiral organic optoelectronics using circularly polarized light (CPL) as the key element in the photonic signal has recently emerged as a next-generation photonic technology. However, it remains challenging to simultaneously achieve high polarization selectivity and superior optoelectronic performance. Supramolecular two-dimensional (2D) chiral organic single crystals may be good candidates for this purpose due to their defect-free nature, molecular diversity, and morphologies. Here, quasi-2D single crystals of chiral perylene diimides with parallelogram and triangle/hexagon morphologies have been selectively fabricated via self-assembly using different cosolvent systems. These materials exhibit amplified circular dichroism (CD) spectral signals, due to their molecular packing modes and supramolecular chirality. Through molecular surface n-doping using hydrazine, chiral single crystals exhibit electron mobility surpassing 1.0 cm2 V-1 s-1, which is one of the highest among chiral organic semiconductors, and excellent optoelectronic functions. Theoretical calculations reveal that the radical anions formed by n-doping increase the electron affinity and/or reduce the energy gap, thus facilitating electron transport. More importantly, the doped organic chiral crystals selectively discriminate CPL handedness with a high anisotropy factor of photoresponsivity (∼0.12). These results demonstrate that surface-doped quasi-2D chiral organic single crystals are highly promising for chiral optoelectronics.

Three-Dimensional Conformation of Folded Polymers in Single Crystals.

The chain-folding mechanism and structure of semicrystalline polymers have long been controversial. Solid-state NMR was applied to determine the chain trajectory of (13)C CH3-labeled isotactic poly(1-butene) (iPB1) in form III chiral single crystals blended with nonlabeled iPB1 crystallized in dilute solutions under low supercooling. An advanced (13)C-(13)C double-quantum NMR technique probing the spatial proximity pattern of labeled (13)C nuclei revealed that the chains adopt a three-dimensional (3D) conformation in single crystals. The determined results indicate a two-step crystallization process of (i) cluster formation via self-folding in the precrystallization stage and (ii) deposition of the nanoclusters as a building block at the growth front in single crystals.

Syntheses, crystal structures, and spectroscopic properties of mixed-ligand cobalt(III) complexes with optically active penicillaminates: Stereospecific interactions and spontaneous crystallizations depending on counter anions

The optically active mixed-ligand complex, [Co(d-pen)(bpma)]+ {pen=penicillaminate; bpma=bis(2-pyridylmethyl)amine}, and its enantiomer, [Co(l-pen)(bpma)]+, were prepared by the reactions of CoCl2·6H2O, bpma, and d-pen2− (or l-pen2−) under aerobic condition. The racemates, [Co(d-pen)(bpma)]0.5[Co(l-pen)(bpma)]0.5X·nH2O (dlCl: X=Cl, n=0; dlNO3: X=NO3, n=0; dlClO4·H2O: X=ClO4, n=1) were also obtained by using dl-pen2− (1:1 mixture of d- and l-pen2−) instead of optically active d- or l-pen2− in the coexistences of the corresponding counter anions. In the presence of PF6− as a counter anion, contrary to the cases of Cl−, NO3−, and ClO4−, a similar reaction results in not racemate but mixture of chiral crystals accompanied by spontaneous crystallizations as chiral single crystals of [Co(d-pen)(bpma)]PF6·H2O (dPF6·H2O) or [Co(l-pen)(bpma)]PF6·H2O (lPF6·H2O). The crystal structures of racemates, dlCl, dlNO3, and dlClO4·H2O, were determined by X-ray crystallography, and compared with those of optically active dPF6·H2O and lPF6·H2O. In the racemic crystals of dlCl, dlNO3, and dlClO4·H2O, characteristic networks are built up by stereospecific π–π stacking and/or hydrogen bonding interactions between two enantiomeric complex cations attendant on auxiliary hydrogen bonds with counter anions. Contrary to dlCl, dlNO3, and dlClO4·H2O, the crystal structures of dPF6·H2O and lPF6·H2O are stabilized by the direct hydrogen-bonding networks between homochiral complex cations.

Perpetually self-propelling chiral single crystals.

When heated, single crystals of enantiomerically pure D- and L-pyroglutamic acid (PGA) are capable of recurring self-actuation due to rapid release of latent strain during a structural phase transition, while the racemate is mechanically inactive. Contrary to other thermosalient materials, where the effect is accompanied by crystal explosion due to ejection of debris or splintering, the chiral PGA crystals respond to internal strain with unprecedented robustness and can be actuated repeatedly without deterioration. It is demonstrated that this superelasticity is attained due to the low-dimensional hydrogen-bonding network which effectively accrues internal strain to elicit propulsion solely by elastic deformation without disintegration. One of the two polymorphs (β) associated with the thermosalient phase transition undergoes biaxial negative thermal expansion (αa = -54.8(8) × 10(-6) K(-1), αc = -3.62(8) × 10(-6) K(-1)) and exceptionally large uniaxial thermal expansion (αb = 303(1) × 10(-6) K(-1)). This second example of a thermosalient solid with anomalous expansion indicates that the thermosalient effect can be expected for first-order phase transitions in soft crystals devoid of an extended 3D hydrogen-bonding network that undergo strongly anisotropic thermal expansion around the phase transition.

Spin solitons and waves in chiral molecular ferrimagnets

Resonance modes corresponding to a spin-soliton resonance have been found in the electron spin resonance spectra of [Cr(CN)6][Mn(S)-pnH-(H2O)]H2O two-dimensional (2D) chiral single crystals and [Mn{(R/S)-pn}]2[Mn{(R/S)-pn}2(H2O)][Cr(CN)6]2 chiral single crystals with a 3D magnetic order. It is also established that the chiral crystals of both types exhibit a spin-wave resonance analogous to the excitation of standing spin waves in thin magnetic films. At the same time, racemic crystals of the first type do not exhibit spin-soliton resonance. The entire body of experimental data indicates that the chirality of crystals influences the spin excitations (standing spin waves and solitons) in these media.

Spin solitons in molecular magnetic materials with the chiral structure

Quasiperiodic sequences of the maxima of microwave absorption with decreasing amplitudes have been observed in a temperature range of 4–50 K in the electron spin resonance spectra of ferrimagnetic chiral single crystals [Mn{(R/S)-pn}]2[Mn{(R/S)-pn}2(H2O)][Cr(CN)6]2, as well as [Cr(CN)6][Mn(S)-pnH-(H2O)]H2O. Theoretical estimates and previous experimental data indicate that the Dzyaloshinskii-Moriya interaction is the main factor determining the chirality of the spin density and the existence of soliton solutions for the spin dynamics in these crystals. The experimental dependences obtained for the distances between the microwave power absorption maxima on the constant component of the magnetic field of the spectrometer correspond to the theoretical predictions for spin solitons in three-dimensional magnetic materials and exhibit another behavior in crystals with quasi-two-dimensional magnetic ordering.

Unexpected formation of chiral single crystals of {NH(n-C3H7)3[MnIICrIII(C2O4)3]}, A 2D oxalate-based material

In an attempt to obtain chiral single crystals of a two-dimensional (2D) bimetallic oxalate-based material by enantioselective auto-assembling of Mn2+ and (rac)-[Cr(C2O4)3]3− templated by the optically active complex (+)-(Rp)-[1-CH2(n-C3H7)3-2-CH3(C5H3)Fe(C5H5)]+, we obtained the unexpected 2D network species {NH(n-C3H7)3[MnCr(C2O4)3]}. X-ray diffraction determination of the structure reveals that the complex crystallizes in the enantiomorphous space group P63. The interlayer spacing of 7.93 Å is the lowest found so far for 2D, bimetallic, oxalate-bridged compounds.

Lanthanoid Chirality as a Tool for Assignment of f–f Transitions. Tb3+ and Tm3+ Diglycolate

Abstract Although chiral studies have proved to be handy in the assignment of transitions in biological molecules, organic molecules and transition metal complexes, its potentiality for lanthanoid transition needs to be demonstrated. The paper explores the usefulness of CD studies in the assignment of lanthanoid transitions with two specific chiral single crystals–thulium diglycolate (Tm3+–DG) and terbium diglycolate (Tb3+–DG). It has been shown that chirality can distinguish ΔJ=0, ±1 transition from others. The need for studies under higher resolution has been pointed out.

ChemInform Abstract: Use of Chiral Single Crystals to Convert Achiral Reactants to Chiral Products in High Optical Yield: Application to the Di‐π‐methane and Norrish Type II Photorearrangements.

AbstractRecrystallization of the diester (I) from ethanol provides prisms with space group Pbca, Z = 8. When recrystallized from cyclohexane, however, (I) affords Pbca crystals plus a dimorph with space group P212121, Z=4.

Use of chiral single crystals to convert achiral reactants to chiral products in high optical yield: application to the di-.pi.-methane and Norrish type II photorearrangements

Use of chiral single crystals to convert achiral reactants to chiral products in high optical yield: application to the di-.pi.-methane and Norrish type II photorearrangements

Lanthanide chirality as a tool for assignment of transitions: Tm 3+ and Tb 3+ pyrogermanates

Although chiral studies have proven to be useful in the assignment of transitions in biological molecules, organic molecules and transition metal complexes, their potential for lanthanide transitions needs to be demonstrated. This paper explores the usefulness of circular dichroism (CD) studies in the assignment of lanthanide Δ J = 0, ± 1 transitions with two chiral single crystals, Tm 2Ge 2O 7 (Tm-PG) and Tb 2Ge 2O 7 (Tb-PG).

大環状シクロファン包接体の構造

The crystallographic study of macrocyclic cyclophane inclusion compounds is reviewed. Cyclophanes such as [2.2.2], [6.6.6], [3.3.3.3] and [6.1.6.1] paracyclophanes and calixarenes with intramolecular hydrophobic cavities surrounded by benzene walls incorporate neutral guest molecules to give molecular inclusion compounds (cavitate) in solutions and in the solid state. Tri-o-thymotide forms chiral single crystals of cage type or channel type clathrate which have enantiomeric excess of guest molecules. [J. Cryst. Soc. Jpn. 28, 261 (1986) ] .

Reactions in Chiral Crystals. Principles Governing Asymmetric Synthesis via Topochemically Controlled Solid-State Photo-Dimerization

Abstract The chemical and crystallographic requirements for utilizing solid-state photodimertization reactions in the medium of chiral single crystals to realize asymmetric syntheses have been considered. Asymmetric syntheses are possible from a variety of reactions in the monocomponent or two-component crystals which have been considered and in favorable cases quantitative optical yields are anticipated. These principles can be extended to other reactions including the formation of chiral cyclobutane photopolymers.

Reactions in chiral crystals. Optically active heterophotodimer formation from chiral single crystals

Reactions in chiral crystals. Optically active heterophotodimer formation from chiral single crystals