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Borocyclic radicals with highly conjugated aromatics were generated from orthoquinone-containing polycyclic aromatic compounds by trapping the photoinduced triplet state with simple boron halide under irradiation with light of appropriate wavelength. The picene-based borocyclic radical was remarkably stable when stored at 23 °C in a desiccator for over 1 year. The crystal structure of this stable radical had a stacking structure of a planar π-conjugated system, and the electrical conductivity was higher than those of ordinary organic radical systems.

An ionic plastic crystal (IPC) is defined as a phase of material in which the orientation orders of constituent ions are melted but the gravity centers are ordered. It is formed by near-globular io...

Two novel coordination compounds of cadmium, [Cd2L1(ssal)2(H2O)3]2·10H2O (1) and {[Cd2L1(dca)4(H2O)]·H2O}n (2) (where L1 = 2,2′,2″-(1-(pyridin-2-ylmethyl)imidazolidine-2,4,5-triyltripyridine), ssal...

Calix[3]aramide-based cylindrical macrocycles were synthesized by the one-step amide coupling reaction of a monomer containing two meta-alkylaminobenzoic acid units linked by para-phenylene bridges. The major products included a meso-form and an enantiomeric pair, with stereochemistry derived from the direction of the amide bonds and their fixed conformation. Mirror-image ECD, VCD, and CPL spectra were observed in the enantiomeric pair and the absolute structure was determined by comparing measured and calculated ECD and VCD spectra.

N,N′-Bis(ortho-substituted phenyl)squaramides afforded chiral crystals, in which squaramide molecules are arranged in one-handed helical networks, upon simple recrystallization. Three types of crystals with different helices were obtained, depending on the substituents or recrystallization solvent. Folded-type intermolecular hydrogen-bonding interactions of squaramides play a key role in forming the helical networks.

N-Phenylbenzenesulfonamides exist preferentially in (+)- or (−)-synclinal conformations, which place the aromatic rings at both ends in the same direction with a twist. We have systematically analyzed the crystal structure of secondary aromatic sulfonamides bearing methyl, ethyl, and/or methoxy groups on the benzene rings. Intermolecular hydrogen bonding between the sulfonamide protons and sulfonyl oxygens was observed in 81 out of 85 crystals. The intermolecular hydrogen-bonding patterns could be classified into four types, i.e. Dimeric, Zigzag, Helical, and Straight patterns, with retention of the synclinal conformation of the sulfonamide moiety. We investigated the relationship between the hydrogen-bonding pattern and the proportion of the compounds that show chiral crystallization. On the basis of our classification of the intermolecular hydrogen bonds of aromatic sulfonamides, the crystals with Dimeric and Zigzag patterns, which both have enantiomeric synclinal conformers, intrinsically become achira...

We designed and synthesized aromatic polyamides with a diphenylacetylene backbone, α-DPA and β-DPA, bearing (S)-α- and (S)-β-methyl-substituted triethyleneglycol (TEG) side chains, respectively, an...

A coculture method with a pathogenic actinomycete of the genus Nocardia and an animal cell line was designed to reconstruct and emulate the initial infection state, and a new cyclic nonapeptide, named nocarjamide (1), was obtained by coculture of Nocardia tenerifensis IFM 10554T and the mouse macrophage-like cell line J774.1 in a modified Czapek–Dox medium. Nocarjamide (1) exhibited Wnt signal-activating effects.

The morphology and stability of amorphous nanoparticles of glibenclamide (GLB) prepared by the antisolvent method using different methods of adding hypromellose (HPMC) were evaluated. Nano-A was prepared by the injection of a dimethyl sulfoxide (DMSO) solution of GLB into the HPMC solution, whereas nano-B was obtained by the injection of a DMSO solution of GLB and HPMC into water. Cryogenic transmission electron microscopy, field-emission scanning electron microscopy, and field-emission transmission electron microscopy, including energy dispersive X-ray spectrometry, revealed that the particles of the nano-A and nano-B samples are hollow spheres and nonspherical nanoparticles, respectively. Powder X-ray diffraction and solid-state NMR measurements showed that GLB is present in an amorphous state in both nano-A and nano-B. The weight ratios of HPMC in the GLB/HPMC nanoparticles were 11 and 16% for nano-A and nano-B, respectively, as determined by solution-state NMR. The glass transition temperatures (Tg) o...

The effect of the side chain chiral center position on the secondary structure of oligomers and polymers of N-substituted 4-aminobenzoic acid was studied. Monomer 1 was prepared from l -alanine methyl ester hydrochloride in seven steps. The poly(p-benzamide) having an α-substituted side chain at the nitrogen atom (α-Me-PA) was obtained from the polymerization of 1 with triethylsilane, CsF, and 18-crown-6 in THF. The circular dichroism (CD) studies in solution demonstrated that α-Me-PA adopted a right-handed helical conformation in protic polar solvents, such as water and methanol, and a random structure in chloroform, indicating that solvophobic interactions played an important role in the helical folding of α-Me-PA. The tetramer of (S)-4-(sec-butylamino)benzoic acid was synthesized as a model compound of α-Me-PA. The single crystal X-ray analysis of the tetramer revealed that the right- and left-handed helical molecules existed in a one-to-one ratio in the crystal, and that the screw pitch of the right-handed helix was shorter than the left-handed helix.

Here, aiming to adopt the phenyl–perfluorophenyl interaction to regulate molecular alignment and arrangement for crystal engineering, we examined and compared in detail the crystal structures of N,N′-diphenylurea compounds 1–6. We found that phenyl–perfluorophenyl interaction greatly influenced the intermolecular arrangement in the crystal, and we were able to prepare a cocrystal of 1 and 2, in which the molecules were alternately arranged under the control of the phenyl–perfluorophenyl interaction. This arrangement was driven by the asymmetric geometry of the hydrogen bonds in the cocrystal (1·2), in which 2, bearing two perfluorophenyl groups, worked as a better hydrogen bond donor. In contrast, NH connected to the phenyl group in 3 proved to be a better hydrogen bond donor due to the intramolecular resonance effect. N,N′-Dimethylated derivatives, 4–6, existed in cis-cis form in the crystal. Antiparallel carbonyl–carbonyl arrangements were observed in 4 and 6, while an unexpected carbonyl–perfluoropheny...

The title compounds are monomeric models for a polythio­noester and a poly(ester-co-thio­noester). The mol­ecules adopt all-trans structures with inter­molecular C⋯S close contacts and C—H⋯π inter­actions. Both crystals have almost the same mol­ecular packing in space group P21/c., The title compounds, C16H14O2S2 and C16H14O3S, which are monomeric models (models D and E) for a polythio­noester and a poly(ester-co-thio­noester), respectively, crystallize in the space group P21/c and are isostructural with each other. The mol­ecule in each crystal is located on an inversion centre and has an all-trans structure. The asymmetric unit comprises one half-mol­ecule. In the crystal, there are inter­molecular C⋯S contacts [3.391 (3) and 3.308 (3) Å for models D and E, respectively] and C—H⋯π inter­actions, which form a layer structure parallel to the bc plane. The carbonyl and thio­carbonyl groups of the model E compound are each disordered over two equivalent sites about the inversion centre with equal occupancies.

Europium(III)–phosphine oxide porous coordination polymers (Eu–PCPs) constructed from Eu(OTf)3 and tris(4-(4′-carboxylphenyl)phenyl)phosphine oxide as ligands are reported. X-Ray diffraction data of Eu–PCPs are collected at 273 K with synchrotron radiation. The europium complex is shown to crystallize in the centrosymmetric orthorhombic space group Pcca. The Eu atom is surrounded by eight neighboring oxygen atoms from six ligands and a coordinated DMF molecule. Furthermore, the two Eu centers are quadruply bridged by four carboxylates. They exhibit an infinite three-dimensional structure that incorporates an open pore structure, which is thermally robust and has an N2 Brunauer–Emmett–Teller surface area of 58.5 m2 g−1 and a micropore volume of 0.756 cm3 g−1. Excitation of the materials led to five sharp emission peaks arising from the 5D0 → 7FJ transitions (J = 0, 1, 2, 3 and 4). The absolute quantum yield of Eu–PCPs is determined as 22% at room temperature. In addition, exposure of single crystals of Eu–PCPs to H2O vapor causes attenuation of the luminescence intensity. This process involves a single-crystal-to-single-crystal transformation. In the crystal structures of the Eu–PCPs, the ligand exchange from DMF to H2O, which acts to quench the lanthanide luminescence, is directly observed.

A chiral tosyl-substituted bis(imidazolidine)pyridine Ts-PyBidine-nickel complex was an efficient catalyst for Friedel-Crafts reaction of indoles with methylene indolinones to give bisindolylmethane compounds having differently oxidized indole units with high enantioselectivities. Alkylation of the products proceeded smoothly in a highly diastereoselective manner, providing an all-carbon quaternary carbon center without significant loss of enantiomeric excess.

To achieve a sustainable-energy society in the future, next-generation highly efficient energy storage technologies, particularly those based on multivalent metal negative electrodes, are urgently required to be developed. Magnesium rechargeable batteries (MRBs) are promising options owing to the many advantageous chemical and electrochemical properties of magnesium. However, the substantially low working voltage of sulfur-based positive electrodes may hinder MRBs in becoming alternatives to current Li-ion batteries. We proposed halide-free noncorrosive ionic liquid-based electrolytes incorporating Mg[TFSA]2 for high-voltage MRB applications. Upon the complexation of Mg[TFSA]2 with tetraglyme (G4) and strict control of the liquid states, the electrolytes achieved excellent anodic stability up to 4.1 V vs. Mg2+/Mg even at 100 °C. The modest electrochemical activities for magnesium deposition/dissolution in the [Mg(G4)][TFSA]2/ionic liquid electrolyte can be improved by certain modifications to the coordination state of [TFSA]-. Dialkyl sulfone was found to be effective in changing the coordination state of [TFSA]- from associated to isolated (free). This coordination change successfully promoted magnesium deposition/dissolution reactions, particularly in the coexistence of ether ligand. By contrast, the coordination of Mg2+ by strongly donating agents such as dimethyl sulfoxide and alkylimidazole led to the complexes inactive electrochemically, suggesting that interaction between Mg2+ and coordination agents predominates the fundamental electrochemical activity. We also demonstrated that an enhancement in the electrochemical activity of electrolytes contributed to improvements in the cycling ability of magnesium batteries with 2.5 V-class MgMn2O4 positive electrodes.

Three dithienobenzimidazole derivative monomers (M1, M2, and M3) were prepared, where M3 was obtained by the oxidation of M1 and identified by the X-ray crystallographic analysis. π-Conjugated homopolymers (P1-0, P2-0, and P3-0) and copolymers (P1-2, P3-1, and P3-2) were synthesized by the palladium-catalyzed coupling polymerizations of M1, M2, and M3. The absorption spectra of the reference compounds (fused R1 and non-fused R2), in conjunction with the optimized ground state structure, certified the importance of the fused dithienobenzimidazole skeleton to increase the effective conjugation length of the polymers. On the basis of the absorption and emission spectra of the π-conjugated polymers in CHCl3, the influence of the thiophene-S,S-dioxide as well as the comonomer structure were investigated to find out that P3-0 and P3-2 exhibited peak maxima at the relatively longer wavelength region due to the donor-acceptor interaction. In addition, the protonation of the imidazole imine group further tuned the optical properties of the π-conjugated polymers by promoting the charge transfer interaction along the polymer main chain, which was supported by the theoretical calculations in detail.

Fused imidazole monomers (1b, 1i, and 2b) having the octyl group were synthesized by the microwave-assisted intramolecular direct arylation, which were subjected to the cross-coupling polymerization. For obtaining π-conjugated polymers with better solubility, fused imidazole monomers (si-1b and si-3b) having the bulky trisiloxane-terminated decyl chain were likewise synthesized and polymerized. On the basis of absorption and emission spectra of obtained π-conjugated polymers in conjunction with the X-ray crystal structure of model compounds and theoretical calculation, the fused structure and coupling partner were found to affect the optical properties in CHCl3 solution as a result of steric and electronic factors. The spectroscopic measurements in film revealed that the bulky trisiloxane group helps π-conjugated polymers to form the π-stacked structure upon thermal annealing. The proton doping experiment was also carried out to find out that the protonation of imidazole nitrogen results in the different ...

(S,S)-Diphenylethylenediamine-derived bis(imidazolidine)pyridine (PyBidine)–Ni(OAc)2 complex catalyzed the asymmetric Michael/aldol reaction of methyleneindolinone and thiosalicylaldehyde to produce (2′R,3S,4′R)-thiochromanyl-spirooxindole having three contiguous stereogenic centers.

A range of bromothiophenes reacted with lithium boranato(tert-butyl)methylphosphide in the absence of transition-metal catalysts under mild conditions to provide the same 2,5-disubstituted and 2-monosubstituted products regardless of the substitution patterns of the starting bromothiophenes.

The incorporation of flexible aliphatic units into otherwise rigid aromatic foldamer sequences may result in different outcomes. The flexible units may have conformational preferences of their own that can be expressed orthogonally to those of the aromatic units. Alternatively, the latter may dictate their folding behavior onto the former. Hybrid aliphatic–aromatic peptidic oligomers combining oxazole-based (O) and quinoline-based (Q) amino acids have been synthesized, and their folding behavior has been investigated in solution by NMR spectroscopy and CD spectroscopy, and in the solid state by X-ray crystallography. Sequences based on the OQQ repeat motif were shown to fold into a canonical aromatic helix motif dominated by the preferences of the quinoline, whereas sequences based on OQ repetitions preferred to fold into a herringbone helix in which the conformational preference of the oxazole units is also expressed.

Two adamantane-bridged tripodal trisimidazolium or trisbenzimidazolium salts were designed as C3v-symmetrical tricarbene ligands and synthesized in good yields. The reaction of the tripodal trisazolium salt precursors with silver oxide provided trisilver hexacarbene complexes bearing a three-dimensional framework. Multinuclear NMR spectroscopy and mass spectrometry data showed that the complexes were symmetric structures of two tricarbene ligands, three metal ions, and three counter anions. X-ray crystallographic analyses revealed that both complex cations adopted a highly twisted conformation. The complex cations built from the trisimidazolium salts were arranged into columnar structures through CH/π interactions, which were assembled into a three-dimensional network structure by intermolecular CH/F interactions via hexafluorophosphate anions. The complex cations generated from the trisbenzimidazolium salts were aligned into columnar structures, which were arranged into a network structure through CH/π interactions. Solvents and counter anions were accommodated in the spaces of the crystalline lattices.

Fused π-conjugated imidazolium compounds bearing two or three long alkoxy chains and various counter anions were systematically prepared following our reported synthetic route. On the basis of DSC measurements and POM observations, the combination of three alkoxy chains longer than the dodecyl group and moderately coordinating anions was important to obtain an enantiotropic mesophase. VT-XRD measurements coupled with a single crystal X-ray structure of a model compound revealed a hexagonal columnar structure supported by ionic interactions. The regularity of the self-organized nanostructure was governed by the alkoxy chain length and the coordinating ability of the counter anion. In the solution state, UV-vis and fluorescence peak maxima were influenced by the number of alkoxy chains and independent of the chain length and anion character. On the contrary, the alkoxy chain length and the coordinating ability of the counter anion had a large impact on the fluorescence spectra in the solid state. A longer wavelength emission at around 560 nm was observed for compounds with the highly regular hexagonal columnar structure. From the result of fluorescence lifetime measurements, the interaction between fused π-conjugated imidazolium cations was suggested.

A first generation of fluorine-free lithium and sodium salts based on the concept of pseudo-delocalized anions has been synthesized with both high purity and yield using water as the solvent in the reaction medium. The salts have been fully characterized by Raman and FT-IR spectroscopies, thermogravimetry, and X-ray crystallography to reveal both basic properties in terms of thermal stability and solubility as well as the local, mainly ion–ion interaction dictated, coordination details and by ionic conductivity and electrochemical stability window measurements as aqueous electrolytes. Together a picture is created of the salts' promise as components in electrolytes – primarily aiming at application in low voltage fluorine-free aqueous lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs).

Alternately N-alkylated aromatic amides such as 1-3 bearing various side chains were designed and synthesized as novel helical foldamers. The CD spectra of oligomers with chiral side chains showed a positive Cotton effect, which indicates that these oligomers take helical conformations in solution. The CD intensity gradually increased with increasing chain length, and pentamer 3d showed remarkably strong CD signals in chloroform. The absorption maxima of the UV spectra were increasingly red shifted with increasing chain length, in contrast to the case of poly( p- N-alkylbenzamide)s. Structure optimization of the oligomers based on the crystal structure of 1a as the monomer unit supported the formation of helical structure with a large cavity and also suggested intramolecular hydrogen bond formation between secondary amides. The results of calculation were consistent with the observed spectroscopic features.

N-Alkylbenzanilides generally exist in cis conformation both in the crystalline state and in various solvents, and this cis conformational preference can be utilized to construct dynamic helical oligoamides. Here, we synthesized the pyrrole-containing amides 2-5 and their oligomers 6-8 and examined their conformations in the crystalline state and in solution. All the N-methylated amides showed cis conformational preference in solution, but the ratio of the cis isomer was decreased when the amide bond was attached at the 4-position of the pyrrole ring, probably because the destabilization of the trans conformer due to electronic repulsion between the pyrrole π electrons and the amide carbonyl lone-pair electrons is reduced due to the small torsion angle between the 5-membered N-pyrrole and the amide bond. In the crystalline state, N-methylated amides showed cis structure, except for compound 5, and cis conformational preference was observed for the pyrrole amides. The CD spectra of oligoamides 15-18 bearing chiral N-substituents were consistent with the presence of dynamic and well-defined chiral foldamers, which were structurally distinct from N-alkylated poly( p-benzamide)s 1.

Macrocyclization of a stable two-turn helical aromatic pentamide, that is, an object with diverging ends that are not prone to cyclization, was made possible by the transient introduction of disruptors of helicity in the form of acid-labile dimethoxybenzyl tertiary amide substituents. After removal of the helicity disruptors, NMR, X-ray crystallography, and computational studies show that the macrocycle possesses a strained structure that tries to gain as high a helical content as possible despite being cyclic. Two points of disruption of helicity remain, in particular a cis amide bond. This point of disruption of helicity can propagate along the cycle in a fluxional manner according to defined trajectories to produce ten degenerate conformations.

Cyclic triamides 4 bearing amidino groups at the meta position of the phenyl rings were synthesized, and their conformational properties in the crystal and in solution were examined. Compound 4a exists as a capsule-type dimer of the enantiomers with a bowl-shaped syn conformation in the crystal state. Compound 4 exists mainly in the syn form in solution, and chiral induction was observed upon addition of a chiral acid to a solution of 4a. Chirality 27:487–491, 2015. © 2015 Wiley Periodicals, Inc.

Chiral bis(imidazolidine)-derived NCN-rhodium complexes ([PhBidine-RhX2 ] and [tBu-PhBidine-RhX2 ]) were prepared by a CH insertion method, and the structures were unequivocally determined by X-ray crystallographic analysis. The [tBu-PhBidine-Rh(OAc)2 ] complex smoothly catalyzed an asymmetric Mannich reaction of malononitrile with N-Boc imines to give products in up to 94 % ee, which are useful for the synthesis of chiral α-amino acids.

Piezoluminescence and liquid crystallinity of anthracene-based bispyridinium salts were investigated in stimulus-responsive luminescent organic crystals and luminescent ionic liquid crystals. The salts possess an anthracene moiety as a fluorophore in their center, and the pyridiniums attached to the anthracene moiety are substituted with trialkoxybenzyl groups. Single crystals of the salts bearing two trimethoxybenzyl groups were obtained as solvates. Ethyl acetate, acetone, and dioxane solvates of the chlorides have almost the same crystal structures with one-dimensional channels. Grinding of the solvated crystals caused the extrusion of the included solvent molecules, which resulted in the red shifts of their fluorescence in the solid state. The dimethyl sulfoxide solvate of the hexafluorophosphate also showed piezoluminescene by grinding. Tris(octyloxy)benzyl and tris(dodecyloxy)benzyl derivatives exhibited rectangular columnar liquid crystals upon being heated for their bromide and tetrafluoroborate s...

Anthracene derivatives possessing a carbamate group and an ester group at their 9- and 10-positions, respectively, were prepared to furnish pairwise packing of anthracene fluorophores in their crystal structures. They were nonluminescent in ethanol solution and showed AIE (aggregation-induced emission) in aqueous ethanol solution and in solid state. Crystal structure analysis of them showed that the H-bonding networks involved in their crystal structures could be classified into four patterns, H-bonding between the carbamate and the ester carbonyl (motif A), H-bonding between the carbamate and the ester oxygen atom (motif B), H-bonded cyclic dimer of carbamate moieties (motif C), and H-bonded chain among carbamate moieties (motif D). Compounds with pairwisely packed anthracene fluorophores showed dimer emission with the longer fluorescence wavelength than others without the pair formation. Fluorescence maximum wavelengths and lifetimes become longer proportional to the degree of overlapping of two facing ...