Plasmonic Enhancement of Chiroptical Property in Enantiomers Using a Helical Array of Magnetoplasmonic Nanoparticles for Ultrasensitive Chiral Recognition.

Recognition of enantiomeric molecules is essential in pharmaceutical and biomedical applications. In this Article, a novel approach is introduced to monitor chiral molecules via a helical magnetic field (hB), where chiral-inactive magnetoplasmonic nanoparticles (MagPlas NPs, Ag@Fe3O4 core-shell NPs) are assembled into helical nanochain structures to be chiral-active. An in-house generator of hB-induced chiral NP assembly, that is, a plasmonic chirality enhancer (PCE), is newly fabricated to enhance the circular dichroism (CD) signals from chiral plasmonic interaction of the helical nanochain assembly with circularly polarized light, reaching a limit of detection (LOD) of 10-10 M, a 1000-fold enhancement as compared to that of conventional CD spectrometry. These enhancements were successfully observed from enantiomeric molecules, oligomers, polymers, and drugs. Computational simulation studies also proved that total chiroptical properties of helical plasmonic chains could be readily changed by modifying the chiral structure of the analytes. The proposed PCE has the potential to be used as an advanced tool for qualitative and quantitative recognition of chiral materials, enabling further application in pharmaceutical and biomedical sensing and imaging.

Open-to-Air RAFT Polymerization on a Surface under Ambient Conditions.

Oxygen (O2)-mediated controlled radical polymerization was performed on surfaces under ambient conditions, enabling on-surface polymer brush growth under open-to-air conditions at room temperature in the absence of metal components. Polymerization of zwitterionic monomers using this O2-mediated surface-initiated reversible addition fragmentation chain-transfer (O2-SI-RAFT) method yielded hydrophilic surfaces that exhibited anti-biofouling effects. O2-SI-RAFT polymerization can be performed on large surfaces under open-to-air conditions. Various monomers including (meth)acrylates and acrylamides were employed for O2-SI-RAFT polymerization; the method is thus versatile in terms of the polymers used for coating and functionalization. A wide range of hydrophilic and hydrophobic monomers can be employed. In addition, the end-group functionality of the polymer grown by O2-SI-RAFT polymerization allowed chain extension to form block copolymer brushes on a surface.

Organophotocatalytic Arene Functionalization: C-C and C-B Bond Formation.

Organophotocatalytic C-C and C-B bond formation reactions of aryl halides have been developed in the presence of an organophotosensitizer, 3,7-di([1,1'-biphenyl]-4-yl)-10-(4-(trifluoromethyl)phenyl)-10H-phenoxazine that has highly negative reduction potential at its photoexcited state. The developed reaction conditions are mild and allow the intermolecular C-C bond formation of the generated aryl radical with electron-rich (hetero)arenes and C-B bond formation with bis(pinacolato)diboron.

First-row early transition metal complexes with a highly sterically demanding triisopropylphenyl amino triphenolate ligand: synthesis and applications.

Amino triphenolate ligands have been widely used for the synthesis of various transition metal complexes aiming at various applications such as ring-opening polymerization, olefin polymerization, and sulfoxidation. However, the introduction of highly sterically demanding aromatic substituents, such as triisopropylphenyl (TRIP), to the amino triphenolate ligand has not been previously reported probably due to the synthetic difficulty. In six-step reactions using commercial materials, a highly sterically demanding amino triphenolate ligand was successfully synthesized, and early transition metal complexes (Ti, V, Cr, Mn) supported by the ligand were also obtained and fully characterized. In addition, titanium and chromium complexes were further used for catalytic sulfoxidation, and polymerization of ethylene, respectively.

Crystal structure of (3,5-dimethyl-1H-pyrrol-2-yl)di-phenyl-phosphine oxide.

The title compound, C18H18NOP, was obtained during a search for new P,N-containing ligands with the potential to generate precatalysts with chromium(III) for selective ethyl-ene oligomerization. In the crystal, mutual pairs of N-H⋯O=P hydrogen bonds link two mol-ecules into a dimer with individual mol-ecules related by a twofold rotation axis. The P=O bond length of 1.4740 (15) Šis not elongated although the O atom is involved in hydrogen bonding. The crystal structure is further stabilized by van der Waals inter-actions between the dimers, linking the mol-ecules into a three-dimensional network structure.

Crystal structure of 2-[bis(1H-pyrazol-1-yl)meth-yl]pyridine.

The title compound, C12H11N5, was synthesized as a potential tridentate ligand to make catalytic metal complexes. The dihedral angle between the pyrazolyl rings is 67.9 (1)°. The most prominent feature in the crystal packing are C-H⋯N hydrogen-bonding inter-actions that link the mol-ecules into a supra-molecular tape along the b-axis direction.

Crystal structure of di-chlorido-{2,6-bis-[(3-phenyl-1H-pyrazol-1-yl)meth-yl]pyridine}cobalt(II).

In the title complex, [CoCl2(C25H21N5)], the Co(II) atom is coordinated by two Cl atoms and two N atoms, provided by a tridentate pyrazolylpyridyl ligand, forming a slightly distorted tetra-hedral geometry [range of angles: 96.51 (10) (chelate ring) to 118.60 (9)°]. The dihedral angle between Cl/Co/Cl and N/Co/N planes is 86.83 (7)°. The chelate ring has the conformation of a distorted boat. The dihedral angle between pyridyl ring and the coordinated pyrazolyl ring is 56.16 (12)°. The uncoordinated pyrazolyl ring is almost perpendicular to the pyridyl ring with the dihedral angle of 87.49 (10)°. In the crystal packing, inter-molecular phenyl-C-H ⋯π(pyrid-yl) inter-actions generate dimeric aggregates. These are connected into a zigzag supra-molecular chain along the c-axis direction via π-π inter-actions [inter-centroid distance between pyridyl and phenyl rings = 3.664 (2) Å].

Highly active chromium(III) complexes based on tridentate pyrazolyl pyridyl ligands for ethylene polymerization and oligomerization.

A set of new chromium(III) [Cr(III)] complexes based on the tridentate ligand HC(Pz)2Py (Pz = pyrazole; Py = pyridine) and its derivatives were prepared, characterized, and evaluated for ethylene polymerization/oligomerization. X-ray single-crystal analyses of the Cr(III) complexes showed tridentate coordination on the fac-octahedral Cr sphere. Upon activation with methylaluminoxane (MAO), the precatalysts and the ligands L1-L3 mixed in situ with Cr(acac)3 were highly active and generally produced polyethylene as a major product. Their catalytic performances were markedly affected by the substituents on the methine carbon atom of the ligands and reaction conditions.

Crystal structure of chlorido-penta-kis(dimethyl sulfoxide-κO)chromium(III) dichloride.

In the complex cation of the title salt, [CrCl(C2H6OS)5]Cl2, the Cr(III) ion is coordinated by one chloride ligand and five O atoms from dimethyl sulfoxide (DMSO) ligands, leading to a slightly distorted octa-hedral coordination environment [O-Cr-O angles range from 86.69 (16) to 92.87 (16)°]. In the crystal, complex cations are arranged in hexa-gonally packed rows parallel to [010], with the chloride counter-anions situated in between. The inter-actions between cations and anions are mainly ionic in nature.

Crystal structure of 2,6-bis-[(1H-pyrazol-1-yl)meth-yl]pyridine.

In the title compound, C13H13N5, the planes of the pyrazolyl groups are nearly perpendicular to that of the central pyridine ring, making dihedral angles of 87.77 (8) and 85.73 (7)°. In the crystal, weak C-H⋯N hydrogen bonds link the mol-ecules into layers extending parallel to (10-1).