Crystal Engineering of Vapochromic Porous Crystals Composed of Pt(II)-Diimine Luminophores for Vapor-History Sensors

A novel Pt­(II) diimine complex, [Pt­(CN)₂­(H₂d<i>p</i>cpbpy)] (<b>1</b>, H₂d<i>p</i>cpbpy = 4,4′-di­(<i>p</i>-carboxyphenyl)-2,2′-bipyridine), was synthesized, and its vapochromic behavior was investigated. The <b><u>y</u></b>ellow <b><u>a</u></b>morphous form of <b>1</b>, <b>1-Ya</b>, transformed into the porous <b><u>o</u></b>range <b><u>c</u></b>rystalline form, <b>1-Oc</b>, upon exposure to ethanol vapor. This behavior is similar to that of the previously reported complex, [Pt­(CN)₂(H₂dcphen)] (<b>2</b>, H₂dcphen = 4,7-dicarboxy-1,10-phenanthroline). X-ray diffraction study showed that <b>1-Oc</b> possessed similar but larger porous channels (14.3 × 8.6 Å) compared to the <b><u>r</u></b>ed <b><u>c</u></b>rystalline form of <b>2</b>, <b>2-Rc</b> (6.4 × 6.8 Å). Although the porous structure of <b>2-Rc</b> was retained after vapor desorption, that of <b>1-Oc</b> collapsed to form the <b><u>o</u></b>range <b><u>a</u></b>morphous solid, <b>1-Oa</b>. However, the orange color was unchanged in this process. The initial color was recovered by grinding <b>1-Oa</b> and <b>2-Rc</b>. These <i>vapor-writing</i> and <i>grinding-erasing</i> functions can be applied to both in situ vapor sensing and vapor-history sensing, i.e., sensors that can memorize the existence of previous vapors. A notable difference was observed for humid air sensitivity; the orange emission of <b>1-Oa</b> was largely unaffected upon exposure to humid air, whereas the red emission of <b>2-Rc</b> was significantly affected. The lesser sensitivity of <b>1-Oa</b> toward humidity is important for stable vapor-history sensor applications

Importance of the Molecular Orientation of an Iridium(III)-Heteroleptic Photosensitizer Immobilized on TiO₂ Nanoparticles

To elucidate the effect of the molecular orientation of a photosensitizing (PS) dye molecule on photoinduced interfacial electron transfer to a semiconductor substrate, we have synthesized two new Ir­(III) heteroleptic complexes each comprising two phosphonic acid groups: [Ir­(ppy)₂(CPbpy)]⁺ and [Ir­(CPppy)₂(bpy)]⁺ (<b>1B</b> and <b>1P</b>, respectively; Hppy = 2-phenylpyridine, bpy = 2,2′-bipyridine, CPbpy = 4,4′-bis­(methylphosphonic acid)-2,2′-bipyridine, and CPppy = 4-(methylphosphonic acid)-2-phenylpyridine). Both Ir­(III) complexes exhibit similar UV–vis absorption spectra and quasi-reversible Ir­(IV)/Ir­(III) redox behavior at a potential of 1.67 V vs NHE. On the other hand, the triplet metal-to-ligand charge-transfer (³MLCT) phosphorescence energy of <b>1B</b> was ∼0.12 eV higher than that of <b>1P</b>. This difference was attributed to the electron-donating methyl phosphonate groups attached to the bpy ligand that destabilize the ³MLCT excited state in which the photoexcited electron is localized in the bpy moiety. Both Ir­(III) PS dyes were immobilized onto the surface of the Pt-co-catalyst-loaded TiO₂ nanoparticles (<b>1B@Pt-TiO</b>_<b>2</b> and <b>1P@Pt-TiO</b>_<b>2</b>). Immobilization was comparable, suggesting that the effect of the positions of the methyl phosphonate groups on the immobilization behavior was negligible. On the other hand, the photocatalytic H₂ evolution activity of <b>1B@Pt-TiO</b>_<b>2</b> was about 6-fold higher than that of <b>1P@Pt-TiO</b>_<b>2</b>, indicating the importance of the methyl phosphonate anchoring group position in regulating not only the redox potentials but also the orientation of the molecular photosensitizer on the semiconductor substrate

Reduction in Crystal Size of Flexible Porous Coordination Polymers Built from Luminescent Ru(II)-Metalloligands

In this study, we examined the reduction in crystal size of the porous coordination polymers (PCPs) {Sr₄(H₂O)₉]<b>­[4Ru]</b>₂­·9H₂O]} (<b>Sr</b>_<b>2</b><b>[4Ru]</b>) and [Mg­(H₂O)₆]­{[Mg₂(H₂O)₃<b>­[4Ru]</b>­·4H₂O} (<b>Mg</b>_<b>2</b><b>[4Ru]</b>) composed of a luminescent metalloligand [Ru­(4,4′-dcbpy)]^4–­(<b>[4Ru]</b>; 4,4′-dcbpy = 4,4′-dicarboxy-2,2′-bipyridine) using a coordination modulation method. Scanning electron microscopy measurements clearly show that the sizes of crystals of <b>Sr</b>_<b>2</b><b>[4Ru]</b> and <b>Mg</b>_<b>2</b><b>[4Ru]</b> were successfully reduced to the mesoscale (about 500 nm width and 10 nm thickness for <b>Sr</b>_<b>2</b><b>[4Ru]</b> (abbreviated as <i>m</i>-<b>Sr</b>_<b>2</b><b>[4Ru]</b>) and about 1 μm width and 30 nm thickness for <b>Mg</b>_<b>2</b><b>[4Ru]</b> (abbreviated as <i>m</i>-<b>Mg</b>_<b>2</b><b>[4Ru]</b>)) using lauric acid as a coordination modulator. Interestingly, the nanocrystals of <i>m</i>-<b>Sr</b>_<b>2</b><b>[4Ru]</b> formed flower-like aggregates with diameters of 1 μm, whereas flower-like aggregates were not formed in <i>m</i>-<b>Mg</b>_<b>2</b><b>[4Ru]</b>. Water vapor adsorption isotherms of these nanocrystals suggest that the water adsorption behavior of <i>m</i>-<b>Sr</b>_<b>2</b><b>[4Ru]</b>, which has a three-dimensional lattice structure containing small pores, is significantly different from that of the bulk <b>Sr</b>_<b>2</b><b>[4Ru]</b> crystal, as shown by the vapor adsorption isotherm. In contrast, <i>m</i>-<b>Mg</b>_<b>2</b><b>[4Ru]</b>, which has a two-dimensional sheet structure, had an adsorption isotherm very similar to that of the bulk sample. These contrasting results suggest that the dimensionality of the coordination framework is an important factor for the guest adsorption behavior of nanocrystalline PCPs

Environmentally Friendly Mechanochemical Syntheses and Conversions of Highly Luminescent Cu(I) Dinuclear Complexes

Luminescent dinuclear Cu­(I) complexes, [Cu₂X₂(dpypp)₂] [<b>Cu-X</b>; X = Cl, Br, I; dpypp = 2,2′-(phenylphosphinediyl)­dipyridine], were successfully synthesized by a solvent-assisted mechanochemical method. A trace amount of the assisting solvent plays a key role in the mechanochemical synthesis; only two solvents possessing the nitrile group, CH₃CN and PhCN, were effective for promoting the formation of dinuclear <b>Cu-X</b>. X-ray analysis revealed that the dinuclear structure with no Cu···Cu interactions, bridged by two dpypp ligands, was commonly formed in all <b>Cu-X</b> species. These complexes exhibited bright green emission in the solid state at room temperature (Φ = 0.23, 0.50, and 0.74; λ_em = 528, 518, and 530 nm for <b>Cu-Cl</b>, <b>Cu-Br</b>, and <b>Cu-I</b>, respectively). Emission decay measurement and TD-DFT calculation suggested that the luminescence of <b>Cu-X</b> could be assigned to phosphorescence from the triplet metal-to-ligand charge-transfer (³MLCT) excited state, effectively mixed with the halide-to-ligand charge-transfer (³XLCT) excited state, at 77 K. The source of emission changed to thermally activated delayed fluorescence (TADF) with the same electronic transition nature at room temperature. In addition, the CH₃CN-bound analogue, [Cu₂(CH₃CN)₂­(dpypp)₂]­(BF₄)₂, was successfully mechanochemically converted to <b>Cu-X</b> by grinding with solid KX in the presence of a trace amount of assisting water

Importance of the Molecular Orientation of an Iridium(III)-Heteroleptic Photosensitizer Immobilized on TiO₂ Nanoparticles

To elucidate the effect of the molecular orientation of a photosensitizing (PS) dye molecule on photoinduced interfacial electron transfer to a semiconductor substrate, we have synthesized two new Ir­(III) heteroleptic complexes each comprising two phosphonic acid groups: [Ir­(ppy)₂(CPbpy)]⁺ and [Ir­(CPppy)₂(bpy)]⁺ (<b>1B</b> and <b>1P</b>, respectively; Hppy = 2-phenylpyridine, bpy = 2,2′-bipyridine, CPbpy = 4,4′-bis­(methylphosphonic acid)-2,2′-bipyridine, and CPppy = 4-(methylphosphonic acid)-2-phenylpyridine). Both Ir­(III) complexes exhibit similar UV–vis absorption spectra and quasi-reversible Ir­(IV)/Ir­(III) redox behavior at a potential of 1.67 V vs NHE. On the other hand, the triplet metal-to-ligand charge-transfer (³MLCT) phosphorescence energy of <b>1B</b> was ∼0.12 eV higher than that of <b>1P</b>. This difference was attributed to the electron-donating methyl phosphonate groups attached to the bpy ligand that destabilize the ³MLCT excited state in which the photoexcited electron is localized in the bpy moiety. Both Ir­(III) PS dyes were immobilized onto the surface of the Pt-co-catalyst-loaded TiO₂ nanoparticles (<b>1B@Pt-TiO</b>_<b>2</b> and <b>1P@Pt-TiO</b>_<b>2</b>). Immobilization was comparable, suggesting that the effect of the positions of the methyl phosphonate groups on the immobilization behavior was negligible. On the other hand, the photocatalytic H₂ evolution activity of <b>1B@Pt-TiO</b>_<b>2</b> was about 6-fold higher than that of <b>1P@Pt-TiO</b>_<b>2</b>, indicating the importance of the methyl phosphonate anchoring group position in regulating not only the redox potentials but also the orientation of the molecular photosensitizer on the semiconductor substrate

Gene Targeting in the Red Alga <i>Cyanidioschyzon merolae</i>: Single- and Multi-Copy Insertion Using Authentic and Chimeric Selection Markers

<div><p>The unicellular red alga <i>Cyanidioschyzon merolae</i> is an emerging model organism for studying organelle division and inheritance: the cell is composed of an extremely simple set of organelles (one nucleus, one mitochondrion and one chloroplast), and their genomes are completely sequenced. Although a fruitful set of cytological and biochemical methods have now been developed, gene targeting techniques remain to be fully established in this organism. Thus far, only a single selection marker, <i>URA_Cm-Gs</i>, has been available that complements the uracil-auxotrophic mutant M4. <i>URA_Cm-Gs</i>, a chimeric <i>URA5.3</i> gene of <i>C. merolae</i> and the related alga <i>Galdieria sulphuraria</i>, was originally designed to avoid gene conversion of the mutated <i>URA5.3</i> allele in the parental strain M4. Although an early example of targeted gene disruption by homologous recombination was reported using this marker, the genome structure of the resultant transformants had never been fully characterized. In the current study, we showed that the use of the chimeric <i>URA_Cm-Gs</i> selection marker caused multicopy insertion at high frequencies, accompanied by undesired recombination events at the targeted loci. The copy number of the inserted fragments was variable among the transformants, resulting in high yet uneven levels of transgene expression. In striking contrast, when the authentic <i>URA5.3</i> gene (<i>URA_Cm-Cm</i>) was used as a selection marker, efficient single-copy insertion was observed at the targeted locus. Thus, we have successfully established a highly reliable and reproducible method for gene targeting in <i>C. merolae.</i> Our method will be applicable to a number of genetic manipulations in this organism, including targeted gene disruption, replacement and tagging.</p></div

Phenotypic modulation of human bladder smooth muscle cells.

<p>(A) Structural changes of a bladder between contraction for expelling and expansion for storage of urine. Arrows represent the direction of intraluminal pressure. (B) A schematic figure for bidirectional phenotypic modulation of human bladder smooth muscle cells. Detailed explanations and discussion for reversible differentiation and isoform-dependent reorganization of actin bundles are outlined in the main text. (C) A schematic figure for the phenotypic modulation of vascular smooth muscle cells. Dedifferentiated SMC is a collective term of a variety of SMC subtypes. Dedifferentiation from contractile phenotype to synthetic phenotype is often irreversible or partially reversible.</p

Gene ontology analysis of upregulated genes in differentiated hBS11 cells.

<p>Gene ontology analysis of upregulated genes in differentiated hBS11 cells.</p

Calcium increase in immortalized human bladder smooth muscle cells.

<p>(A) Differentiated hBS11 cells were preloaded with a calcium sensitive dye Fluo-4 AM, and then stimulated with a cholinergic agonist carbachol (1 mM). The cells were observed under epifluorescence microscopy. Fluorescent images correspond to the frames 2, 5, 10, 20, 31, and 37 of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186584#pone.0186584.s012" target="_blank">S3 Video</a>. Scale bar, 10 μm. (B) Differentiated hBS11 cells were treated as described in (A). The cells were observed under phase contrast and epifluorescence microscopy. The phase contrast image was taken before stimulation with carbachol. Fluorescent images correspond to the frames 28 and 34 of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186584#pone.0186584.s013" target="_blank">S4 Video</a>. A circle represents a cell-to-cell contact region between neighboring cells named #1 and #2 in a phase contrast image before carbachol stimulation (left panel). Calcium signaling was conducted between neighboring cells (middle and right panels). (C) hBS11 cells were preloaded with Fluo-4 AM for 1 h on day 14 or 19 of differentiation culture and then stimulated with a cholinergic agonist carbachol (50 μM) for 30 s. Digital fluorescent imaging was obtained using a two-photon confocal microscope. ΔF/F₀ represents percent changes in the fluorescence intensity over resting levels. (a) Effect of the muscarinic receptor antagonist atropine (5 μM) on carbachol-induced intracellular Ca²⁺ elevation. Horizontal bar represents the period of exposure to carbachol. F/F₀ of hBS11 cells before (open circles), during the treatment of atropine (red circles), and after washing off atropine (blue circles) are shown. (b) Pooled data regarding the effect of atropine on carbachol-induced intracellular Ca²⁺ elevation. Atropine treatment significantly blocked the Ca²⁺ elevation. Statistical significance (p-value) was estimated using the multi-comparison Dunnett’s test (n = 8). Each dashed line connecting open circles represents data obtained from the same cells. Each bar represents average and standard error of mean. (D) hBS11 cells were cultured for 14 days in pmDM and preloaded with Fluo-4 AM. Next, the medium was switched to a calcium-deleted Krebs-Ringer solution supplemented with 90 mM KCl. The cells were sequentially observed using epifluorescence microscopy and time-lapse recordings with a 30-second interval. Incubation time before and after stimulation with calcium (2.8 mM) is shown at the upper panel corners. Scale bar, 10 μm.</p

Impact of Photosensitizing Multilayered Structure on Ruthenium(II)-Dye-Sensitized TiO₂‑Nanoparticle Photocatalysts

To improve the efficiency of photoinduced charge separation on the surface of dye-sensitized TiO₂ nanoparticles, we synthesized the Ru­(II)-photosensitizer-immobilized, Pt-cocatalyst-loaded TiO₂ nanoparticles <b>RuCP</b>^<b>2</b>@Pt–TiO₂, <b>RuCP</b>^<b>2</b>–Zr–<b>RuP</b>^<b>6</b>@Pt–TiO₂, and <b>RuCP</b>^<b>2</b>–Zr–<b>RuP</b>^<b>4</b>–Zr–<b>RuP</b>^<b>6</b>@Pt–TiO₂ (<b>RuCP</b>^<b>2</b> = [Ru­(bpy)₂(mpbpy)]^2–, <b>RuP</b>^<b>4</b> = [Ru­(bpy)­(pbpy)₂]^6–, <b>RuP</b>^<b>6</b> = [Ru­(pbpy)₃]^10–, H₄mpbpy = 2,2′-bipyridine-4,4′-bis­(methanephosphonic acid), and H₄pbpy = 2,2′-bipyridine-4,4′-bis­(phosphonic acid)) using phosphonate linkers with bridging Zr⁴⁺ ions. X-ray fluorescence and ultraviolet–visible absorption spectra revealed that a layered molecular structure composed of Ru­(II) photosensitizers and Zr⁴⁺ ions (i.e., <b>RuCP</b>^<b>2</b>–Zr–<b>RuP</b>^<b>6</b> and <b>RuCP</b>^<b>2</b>–Zr–<b>RuP</b>^<b>4</b>–Zr–<b>RuP</b>^<b>6</b>) was successfully formed on the surface of Pt–TiO₂ nanoparticles, which increased the surface coverage from 0.113 nmol/cm² for singly layered <b>RuCP</b>^<b>2</b>@Pt–TiO₂ to 0.330 nmol/cm² for triply layered <b>RuCP</b>^<b>2</b>–Zr–<b>RuP</b>^<b>4</b>–Zr–<b>RuP</b>^<b>6</b>@Pt–TiO₂. The photocatalytic H₂ evolution activity of the doubly layered <b>RuCP</b>^<b>2</b>–Zr–<b>RuP</b>^<b>6</b>@Pt–TiO₂ was three times higher than that of the singly layered <b>RuCP</b>^<b>2</b>@Pt–TiO₂, whereas the activity of triply layered <b>RuCP</b>^<b>2</b>–Zr–<b>RuP</b>^<b>4</b>–Zr–<b>RuP</b>^<b>6</b>@Pt–TiO₂ was less than half of that for <b>RuCP</b>^<b>2</b>@Pt–TiO₂. The photosensitizing efficiencies of these Ru­(II)-photosensitizer-immobilized nanoparticles for the O₂ evolution reaction catalyzed by the Co­(II)-containing Prussian blue analogue [Co^II(H₂O)₂]_1.31[{Co^III(CN)₆}_0.63{Pt^II(CN)₄}_0.37] decreased as the number of Ru­(II)-photosensitizing layers increased. Thus, crucial aspects of the energy- and electron-transfer mechanism for the photocatalytic H₂ and O₂ evolution reactions involve not only the Ru­(II)-complex-TiO₂ interface but also the multilayered structure of the Ru­(II)-photosensitizers on the Pt–TiO₂ surface