Anion-Directed Formation and Degradation of an Interlocked Metallohelicate

Although there are many examples of catenanes, those of more complex mechanically interlocked molecular architectures are rare. Additionally, little attention has been paid to the degradation of such interlocked systems into their starting complexes, although formation and degradation are complementary phenomena and are equally important. Interlocked metallohelicate, [(Pd₂L₄)₂]⁸⁺ (<b>2</b>⁸⁺), is a quadruply interlocked molecular architecture consisting of two mechanically interlocked monomers, [Pd₂L₄]⁴⁺ (<b>1</b>⁴⁺). <b>2</b>⁸⁺ has three internal cavities, each of which encapsulates one NO₃^– ion (1:3 host–guest complex, <b>2</b>⊃(NO₃|NO₃|NO₃)⁵⁺) and is characterized by unusual thermodynamic stability. However, both the driving force for the dimerization and the origin of the thermodynamic stability remain unclear. To clarify these issues, BF₄^–, PF₆^–, and OTf^– have been used to demonstrate that the dimerization is driven by the anion template effect. Interestingly, the stability of <b>2</b>⁸⁺ strongly depends on the encapsulated anions (<b>2</b>⊃(NO₃|NO₃|NO₃)⁵⁺ ≫ <b>2</b>⊃(BF₄|BF₄|BF₄)⁵⁺). The origins of this differing thermodynamic stability have been shown through detailed investigations to be due to the differences in the stabilization of the interlocked structure by the host–guest interaction and the size of the anion. We have found that 2-naphthalenesulfonate (ONs^–) induces the monomerization of <b>2</b>⊃(NO₃|NO₃|NO₃)⁵⁺ via intermediate <b>2</b>⊃(ONs|NO₃|ONs)⁵⁺, which is formed by anion exchange. On the basis of this finding, and using <i>p</i>-toluenesulfonate (OTs^–), the physical separation of <b>2</b>⊃(NO₃|NO₃|NO₃)⁵⁺ and <b>1</b>⁴⁺ as OTs^– salt was accomplished

Homochiral 1D Helical Chain Based on an Achiral Cu(II) Complex

Self-assembly of an achiral [Cu­(L)] complex produced a homochiral helical chain [Cu­(L)]₃·2H₂O (<b>1</b>) (L = 2-dimethylaminoethyl­(oxamato)). Interestingly, complex <b>1</b> obtained in our laboratory exhibits only a left-handed helical chain without any chiral source. Single-crystal X-ray analysis revealed the absolute structure and homochirality of its helical chain structure in the space group of <i>P</i>3₂. Solid-state circular dichroism (CD) spectra confirmed the high enantio excess of the crystals obtained in different synthesis batches. Magnetic susceptibility measurements reveal a relatively strong intrachain antiferromagnetic interaction between Cu­(II) centers via an oxamato bridge (<i>J</i> = −74.4 cm^–1)

Homochiral 1D Helical Chain Based on an Achiral Cu(II) Complex

Self-assembly of an achiral [Cu­(L)] complex produced a homochiral helical chain [Cu­(L)]₃·2H₂O (<b>1</b>) (L = 2-dimethylaminoethyl­(oxamato)). Interestingly, complex <b>1</b> obtained in our laboratory exhibits only a left-handed helical chain without any chiral source. Single-crystal X-ray analysis revealed the absolute structure and homochirality of its helical chain structure in the space group of <i>P</i>3₂. Solid-state circular dichroism (CD) spectra confirmed the high enantio excess of the crystals obtained in different synthesis batches. Magnetic susceptibility measurements reveal a relatively strong intrachain antiferromagnetic interaction between Cu­(II) centers via an oxamato bridge (<i>J</i> = −74.4 cm^–1)

Stereospecific Synthesis of Tris-heteroleptic Tris-cyclometalated Iridium(III) Complexes via Different Heteroleptic Halogen-Bridged Iridium(III) Dimers and Their Photophysical Properties

Herein, we report on the stereospecific synthesis of two single isomers of tris-heteroleptic tris-cyclometalated iridium­(III) (Ir­(III)) complexes composed of three different nonsymmetric cyclometalating ligands via heteroleptic halogen-bridged Ir dimers [Ir­(tpy)­(F₂ppy)­(μ-Br)]₂ <b>17b</b> and [Ir­(mpiq)­(F₂ppy)­(μ-Br)]₂ <b>27b</b> (tpyH: (2-(4′-tolyl)­pyri­dine) and F₂ppyH: (2-(4′,6′-di­fluoro­phenyl)­pyridine), and mpiqH: (1-(4′-methyl­phenyl)­iso­quinoline)) prepared by Zn²⁺-promoted degradation of Ir­(tpy)₂­(F₂ppy) <b>21</b> and Ir­(mpiq)₂­(F₂ppy) <b>26</b>, as reported by us. Subsequently, <b>17b</b> and <b>27b</b> were converted to the tris-heteroleptic tris-cyclometalated Ir complexes Ir­(tpy)­(F₂ppy)­(mpiq) <b>25</b> consisting of tpy, F₂ppy, and mpiq, as confirmed by spectroscopic data and X-ray crystal structure analysis. The first important point in this work is the selective synthesis of specific isomers among eight possible stereoisomers of Ir complexes having the same combination of three cyclometalating ligands. Namely, two meridional forms of <b>25</b> were synthesized and isolated. The second finding is that the different stereoisomers of <b>25</b> have different stability. Finally, different stereoisomers exhibit different emission spectra. Namely, one of its stereoisomers <b>25a</b> exhibits a single broad emission from <i>ca</i>. 550 nm to <i>ca</i>. 650 nm (orange emission), while stereoisomer <b>25c</b> emits dual emission at <i>ca</i>. 509 nm and <i>ca</i>. 600 nm (pale pink emission), as supported by time-dependent density functional theory calculation. To the best of our knowledge, this is the first report of the selective and efficient synthesis of different stereoisomers of tris-heteroleptic tris-cyclometalated Ir­(III) complexes that have different stabilities and different photophysical properties

Facile Synthetic Route to Highly Luminescent Sila[7]helicene

A facile synthetic route to dimethylsila[7]helicene by using a Lewis acid catalyzed double-cyclization reaction for construction of the twisted two phenanthrene moieties is described. Sila[7]helicene exhibited a high fluorescence quantum yield and a realatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminencence (CPL) for small molecules

Facile Synthetic Route to Highly Luminescent Sila[7]helicene

A facile synthetic route to dimethylsila[7]helicene by using a Lewis acid catalyzed double-cyclization reaction for construction of the twisted two phenanthrene moieties is described. Sila[7]helicene exhibited a high fluorescence quantum yield and a realatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminencence (CPL) for small molecules

Efficient Synthesis of Tris-Heteroleptic Iridium(III) Complexes Based on the Zn²⁺-Promoted Degradation of Tris-Cyclometalated Iridium(III) Complexes and Their Photophysical Properties

We report on the efficient synthesis of tris-heteroleptic iridium (Ir) complexes based on the degradation of tris-cyclometalated Ir complexes (IrL₃, L: cyclometalating ligand) in the presence of Brønsted and Lewis acids such as HCl (in 1,4-dioxane), AlCl₃, TMSCl, and ZnX₂ (X = Br or Cl), which affords the corresponding halogen-bridged Ir dimers (μ-complexes). Tris-cyclometalated Ir complexes containing electron-withdrawing groups such as fluorine, nitro, or CF₃ moieties on the ligands were less reactive. This different reactivity was applied to the selective degradation of heteroleptic Ir complexes such as <i>fac</i>-Ir­(tpy)₂(F₂ppy) (<i><b>fac</b></i><b>-12</b>) (tpy: 2-(4′-tolyl)­pyridine and F₂ppy: 2-(4′,6′-difluorophenyl)­pyridine), <i>mer</i>-Ir­(tpy)₂(F₂ppy) (<i><b>mer</b></i><b>-12</b>), and <i>mer</i>-Ir­(mpiq)₂(F₂ppy) (<i><b>mer</b></i><b>-15</b>) (mpiq: 1-(4′-methylphenyl)­isoquinoline). For example, the reaction of <i><b>mer</b></i><b>-12</b> with ZnBr₂ gave the heteroleptic μ-complex [{Ir­(tpy)­(F₂ppy)­(μ-Br)}₂] <b>27b</b> as a major product, resulting from the selective elimination of the tpy ligand of <i><b>mer</b></i><b>-12</b>, and treatment of <b>27b</b> with acetylacetone (acacH) afforded the corresponding tris-heteroleptic Ir complex Ir­(tpy)­(F₂ppy)­(acac)<b>18</b>. In addition, another tris-heteroleptic Ir complex <b>35a</b> having 8-benzene­sulfonyl­amido­quinoline (8BSQ) ligand was synthesized. Mechanistic studies of this degradation reaction and the photochemical properties, especially a dual emission, of these newly synthesized tris-heteroleptic Ir complexes are also reported

Synthesis, Characterization, X‑ray Crystal Structure, DFT Calculations, and Catalytic Properties of a Dioxidovanadium(V) Complex Derived from Oxamohydrazide and Pyridoxal: A Model Complex of Vanadate-Dependent Bromoperoxidase

A vanadium­(V) complex with the formula [Et₃NH]­[V^VO₂(sox-pydx)] with a new tridentate ligand 2-[2-[[3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl]­methylene]­hydrazinyl]-2-oxoacetamide (soxH-pydxH), obtained by condensation of oxamohydrazide and pyridoxal (one of the forms of vitamin B₆), has been synthesized. The compound was characterized by various analytical and spectroscopic methods, and its structure was determined by single-crystal X-ray diffraction technique. Density functional theory (DFT) and time-dependent DFT calculations were used to understand the electronic structure of the complex and nature of the electronic transitions observed in UV–vis spectra. In the complex, vanadium­(V) is found to be pentacoordinated with two oxido ligands and a bianionic tridentate ONO-donor ligand. The vanadium center has square-pyramidal geometry with an axial oxido ligand, and the equatorial positions are occupied by another oxido ligand and a phenolato oxygen, an imine nitrogen, and a deprotonated amide oxygen of the hydrazone ligand. A DFT-optimized structure of the complex shows very similar metrical parameters as determined by X-ray crystallography. The O₄N coordination environment of vanadium and the hydrogen-bonding abilities of the pendant amide moiety have a strong resemblance with the vanadium center in bromoperoxidase enzyme. Bromination experiments using H₂O₂ as the oxidizing agent, with model substrate phenol red, and the vanadium complex as a catalyst show a remarkably high value of <i>k</i>_cat equal to 26340 h^–1. The vanadium compound also efficiently catalyzes bromination of phenol and salicylaldehyde as well as oxidation of benzene to phenol by H₂O₂

Novel Means of Controlling the Solid-State Circular Dichroism Property in a Supramolecular Organic Fluorophore Comprising 4-[2-(Methylphenyl)ethynyl]benzoic Acid by Varying the Position of the Methyl Substituent

The solid-state circular dichroism (CD) of a 4-[2-(methylphenyl)­ethynyl]­benzoic acid/amine supramolecular organic fluorophore can be controlled by changing the position of the methyl substituent of the methylphenylethynyl unit on the achiral 4-[2-(methylphenyl)­ethynyl]­benzoic acid component molecule, instead of changing the chirality of the chiral amine component molecule

Odds ratio with 95% confidence interval of diabetes according to overtime work hours stratified by participant characteristics.

<p>Abbreviations: BMI, body mass index; Ref, reference.</p><p>*<i>P</i> for trend obtained from multiple logistic regression analysis by assigning 23, 62, 90, and 100 to categories of overtime work.</p>†<p>Adjusted for age (continuous), sex, company, smoking status (never, past, or current), and BMI (kg/m², continuous) in 4 companies (n = 41,081).</p>‡<p>48 women in 1 company were excluded in this analysis due to no diabetic patients.</p>§<p>Adjusted for age (continuous), sex, company, smoking status (never, past, or current), BMI (kg/m², continuous), alcohol use (non-drinker, drinker consuming >0 to <23 g, 23 to <46 g, or ≥46 g of ethanol per day), sleep duration (<6 hours, 6 to <7 hours, or ≥7 hours per day), physical activity (<150 min or ≥150 min per week), family history of diabetes (yes or no), shift work (yes or no), department (field work or non-field work), and job position (high or low) in 1 company (n = 33,807).</p