Controlling the thermodynamic stability of conformational isomers of bistricyclic aromatic enes by introducing boron and silicon atoms.

Overcrowded bistricyclic aromatic enes (BAEs) have several conformational isomers, including twisted and -folded conformers. These compounds change color depending on their conformation because each isomer exhibits distinct absorption bands. In this study, we introduced several heteroatoms such as boron and silicon into BAEs to control the energy difference between the twisted and -folded conformers, thereby achieving chromic properties.

Twisted diphenoquinones fused with thiophene rings: thiophene analogs of bianthrone.

The twisted conformer of bistricyclic aromatic enes (BAEs) has a small HOMO-LUMO gap owing to the twisted double bond. In this study, we synthesized diphenoquinones fused with thiophene rings as a new twisted conformer-predominant BAE. They exhibited deep LUMO energy levels and apparent n-type semiconductor properties.

Separation of iodate, bromide, nitrite, nitrate, and iodide in seawater by ion chromatography using 1-aminoundecyl group chemically bonded silica columns.

The separation and detection of six common inorganic anions (iodate (IO), bromate (BrO), bromide (Br), nitrite (NO), nitrate (NO), and iodide (I)) in pure water and 35 ‰ artificial seawater were examined by ion chromatography (IC). As packing materials of separation columns, 1-aminoundecyl group chemically bonded silica (AUS) gels were prepared. Separation of the anions in pure water was achieved using separation columns (150 mm × 4.

The Preparation of Dithieno[3,2-:4,5-']germole, and Its Application as a Donor Unit in Conjugated D-A Compounds.

Group 14 metalloles have attracted much attention as core structures of conjugated functional materials. In this work, we prepared dithieno[3,2-:4,5-']germole as a new unsymmetrically condensed dithienogermole and benzo[4,5]thieno[2,3-c]germole as the benzene-condensed analog. The electronic states and properties of these unsymmetrically condensed germoles are discussed on the basis of the results of optical and electrochemical measurements with the help of quantum chemistry calculations on the simplified model compounds.

Synthesis of Unsymmetrically Condensed Benzo- and Thienotriazologermoles.

Germoles and siloles unsymmetrically condensed with heteroaromatic units are attracting much interest. In this study, compounds containing a triazologermole core unit condensed with a benzene or thiophene ring were prepared. Thienotriazologermole was subjected to bromination to obtain the bromide, which underwent transformation via the palladium-catalyzed Stille coupling reaction to form triphenylamine-substituted thienotriazolegermole, with an effective extension of conjugation.

Insights into mechanistic interpretation of crystalline-state reddish phosphorescence of non-planar π-conjugated organoboron compounds.

Metal-free room-temperature phosphorescent (RTP) materials are attracting attention in such applications as organic light-emitting diodes and bioimaging. However, the chemical structures of RTP materials reported thus far are mostly predominantly based on π-conjugated systems incorporating heavy atoms such as bromine atoms or carbonyl groups, resulting in limited structural diversity. On the other hand, triarylboranes are known for their strong Lewis acidity and deep LUMO energy levels, but few studies have reported on their RTP properties.

Phosphorescence Properties of Boron/Bismuth Hybrid Conjugated Materials.

By introducing main-group elements such as boron and bismuth to π-conjugated systems, it is possible to modify the optical properties of π-conjugated materials through orbital interactions between the orbital on the elements and π/π*-orbitals, and the heavy atom effect. Moreover, bismuth, which is the heaviest stable element, induces a significant heavy atom effect, making organobismuth compounds promising for applications as phosphorescent materials. In this study, we synthesized new room-temperature phosphorescent materials by incorporating bismuth into thiophene units.

Synthesis and Properties of Boron-Containing Heteromerous Bistricyclic Aromatic Enes: Structural Effects on Thermodynamic Stability and Photoreactivity.

Overcrowded bistricyclic aromatic enes (BAEs) have several conformations such as twisted and anti-folded conformers, and their stereochemistry and chromism have been studied in earnest. In this study, boron-containing heteromerous BAEs having various tricyclic structures were synthesized and their photophysical properties investigated. Single-crystal X-ray analysis revealed that the introduction of a rigid fluorene unit resulted in a twisted conformer, whereas the introduction of flexible units such as thioxanthene and 9,9-dimethyl-9,10-dihydroanthracene units resulted in an anti-folded conformer.

Highly luminescent antiaromatic diborinines with fused thiophene rings.

Tricoordinate boron-incorporated π-conjugated systems are widely investigated as optoelectronic materials because of their unique p-π* orbital interactions and high Lewis acidity. Among them, thiophene-fused diborinines are characterized by moderate antiaromaticity and extended conjugation. In this work, we have developed two new dithienodiborinines with and symmetries, which exhibited completely different optical properties.

Development of Highly Water-Permeable Robust PSQ-Based RO Membranes by Introducing Hydroxyethylurea-Based Hydrophilic Water Channels.

Copolymerization of bis[3-(triethoxysilyl)propyl]amine (BTESPA) and -(2-hydroxyethyl)-'-[3-(triethoxysilyl)propyl]urea (HETESPU) provided highly permeable robust reverse osmosis (RO) membranes that have an organically bridged polysilsesquioxane (PSQ) structure. The RO experiments with NaCl aqueous solution (2000 ppm) indicated that the introduction of hydroxyethylurea groups markedly improved the permeability of water (1.86 × 10 m/msPa) to approximately 19 times higher than that of a membrane prepared via the BTESPA homopolymerization, with NaCl rejection remaining nearly unchanged (96%).

Robust and Transparent Antifogging Polysilsesquioxane Film Containing a Hydroxy Group.

Poly(glycidyloxypropyl)silsesquioxane (PGPS) was successfully synthesized by hydrolysis and polycondensation using the nitrogen flow method. A poly(3-(2,3-dihydroxypropoxypropyl)silsesquioxane) (PSQ-OH) film was prepared via two routes. In route A, PSQ-OH was prepared by the hydrolysis of the epoxy group of PGPS in an aqueous hydrochloric acid (HCl)/tetrahydrofuran solution, affording a diol group; then, PSQ-OH was coated on a glass substrate and heated.

Asymmetric Synthesis of Bridged -Heterocycles with Tertiary Carbon Center through Barbas Dienamine-Catalysis: Scope and Applications.

A direct aza-Diels-Alder reaction between 2-aryl-3-indolin-3-ones and cyclic-enones has been developed to access chiral indolin-3-one fused polycyclic bridged compounds. This method proceeds via proline-catalyzed Barbas-dienamine intermediate formation from various cyclic-enones such as 2-cyclopenten-1-one, 2-cyclohexene-1-one, and 2-cycloheptene-1-one, followed by a reaction with 2-aryl-3-indol-3-ones. Several indolin-3-ones fusing [2.

Crack- and Shrinkage-Free Ethylene-Bridged Polysilsesquioxane Film Prepared by a Hydrosilylation Reaction.

With the aim of developing an improved strategy for the preparation of ethylene-bridged polysilsesquioxanes as thermal insulator materials, this paper describes the synthesis of a crack- and shrinkage-free ethylene-bridged polysilsesquioxane film by the hydrosilylation reaction of hydrodimethyl-silylated oligomethylsilsesquioxane (MSQ-SiH) and dimethylvinyl-silylated oligomethylsilsesquioxane (MSQ-SiVi) in the presence of Karstedt's catalyst. Polysilsesquioxane precursors were prepared by the sol-gel reaction of triethoxymethylsilane and the successive capping reaction with chlorodimethylsilane and chlorodimethylvinylsilane. The obtained ethylene-bridged polysilsesquioxane film showed lower density and thermal diffusivity (1.

Thiophene-based twisted bistricyclic aromatic ene with tricoordinate boron: a new n-type semiconductor.

The incorporation of tricoordinate boron into conjugated systems is of current interest in the field of organic electronics. In this study, a tricoordinate boron-embedded thiophene-based bistricyclic aromatic ene (BAE) was synthesized as a new boron-containing conjugated system. The combination of tricoordinate boron and fused thiophene rings imposed the twisted conformation in the BAE structure, resulting in the narrow energy absorption with the low-lying LUMO.

Optical Characteristics of Hybrid Macrocycles with Dithienogermole and Tricoordinate Boron Units.

The introduction of unconventional elements into π-conjugated systems has been studied to manipulate the electronic states and properties of compounds. Herein, boron- and germanium-containing hybrid macrocycles, as a new class of element-hybrid conjugated systems, have been synthesized. The palladium-catalyzed Stille cross coupling of bis(bromothienyl)borane and bis(trimethylstannylthienyl)- or bis(trimethylstannylphenyl)-substituted dithienogermoles as the boron- and germanium-containing building blocks, respectively, produced a mixture of several macrocyclic compounds.

Direct Amine-Catalyzed Enantioselective Synthesis of Pentacyclic Dibenzo[,][1,4]oxazepine/Thiazepine-Fused Isoquinuclidines along with DFT Calculations.

A direct protocol for the asymmetric synthesis of dibenzoxazepine/thiazepine-fused [2.2.2] isoquinuclidines is developed.

Crystal Structures and Phosphorescent Properties of Group 14 Dipyridinometalloles and Their Copper Complexes.

We recently reported dipyridinosilole (DPyS) and dipyridinogermole (DPyG) as π-conjugated units that show low-temperature phosphorescence. A copper complex of DPG shows solid-state phosphorescence at room temperature. In this work, we prepared diphenyldipyridinostannole (DPySn1).

Model-based research toward design of innovative materials: molecular weight prediction of bridged polysilsesquioxanes.

Toward the design and manipulation of innovative materials, we propose a new concept called "model-based research (MBR)". In MBR, measurable physical and chemical properties of materials are mathematically modelled by explanatory parameters obtained by computer simulation from an atomistic point of view. To demonstrate the potential of MBR, we modelled the molecular weights of a series of polysilsesquioxanes with respect to the HO/silane molar ratio employed for the polymerization of monomers bis(triethoxysilyl)methane, ethane, ethylene, and acetylene (BTES-M, -E1, -E2, and -E3), as an example.

Direct comparison of dithienosilole and dithienogermole as π-conjugated linkers in photosensitizers for dye-sensitized solar cells.

Dithienosilole (DTS) and dithienogermole (DTG) are useful building units of π-conjugated organic materials. In the present work, donor-π-acceptor (D-π-A) dyes with bis(dihexyloxyphenyl)aminophenyl, DTS or DTG, and pyridine or cyanoacrylic acid as the donor (D), the π-conjugated linker (π), and the acceptor (A) units, respectively, were prepared and their optical properties were investigated. The D-π-A dyes exhibited strong absorption in the visible region, indicating efficient intramolecular donor-acceptor interaction.

Helical assembly of a dithienogermole exhibiting switchable circularly polarized luminescence.

Dithienogermole derivatives S- and R-1 possessing phenylisoxazoles and chiral side chains were synthesized. The helical assembly of 1 in methylcyclohexane exhibited circularly polarized luminescence (CPL). The CPL signals of the assembly in the elongation regime were inverted with respect to those in the nucleation regime.

Bis(diphenylphosphinyl)-functionalized dipyrido-annulated NHC towards copper(i) and silver(i).

The coordination chemistry of our recently isolated bis(diphenylphosphinyl)-functionalized dipyrido-annulated NHC (N-heterocyclic carbene), dpa-NHC, towards copper(i) and silver(i) has been studied. Based on dpa-NHC, two dinuclear silver and copper complexes [2, (AgL) and 3, (CuL)], two tetranuclear copper complexes {4, [CuL(NCMe)] and 6, (CuLBr)} and a pentanuclear copper complex [5, (CuLBr)] exhibiting strong intramolecular metal-metal interactions were achieved and characterized. All the complexes exhibited dynamic behavior in solution, in which the NMR coalescence of 2 was well resolved at low temperature (below 208 K) and dissociation for 2 was observed according to the calculated Eyring plot.

Luminescent Di- and Tetranuclear Gold Complexes of Bis(diphenylphosphinyl)-Functionalized Dipyrido-Annulated N-Heterocyclic Carbene.

Phosphine-functionalized N-heterocyclic carbene (NHC) ligands are known to complex group 11 metal centers to form multinuclear complexes with photoluminescence properties. This study reports a structurally rigid ortho-substituted dipyrido-annulated NHC with T-shape coordination geometry and its di- and tetranuclear gold(I) complexes. The free ligand as well as all metal complexes are found luminescent at room temperature and phosphorescent at 77 K.

Intramolecular Energy Transfer in Dithienogermole Derivatives.

Dithienogermole (DTG) has been applied as a useful building unit of optical/semiconducting materials for organic optoelectronic devices because of its extended conjugation, high chemical stability, and good emissive properties. Although DTG has two substituents on the Ge atom, the substituents have been limited to simple alkyl and aryl groups in previous work. In this work, to further uncover the new functionalities of this useful building unit, various π-conjugated groups were introduced on Ge of DTG.

Mitochondria-Targeting Polyamine-Protoporphyrin Conjugates for Photodynamic Therapy.

Two polyamine derivatives of protoporphyrin IX (PPIX) were tested as photodynamic therapy (PDT) agents in HT29 colorectal cancer and HEP3B liver cancer cell lines. These compounds exhibit excellent singlet oxygen quantum yields and show strong in vitro PDT efficacy after 660 nm laser irradiation, whereas exogenous PPIX itself exhibits much weaker PDT effects. Confocal microscopy imaging studies reveal that a protoporphyrin derivative with eight amine moieties has excellent water solubility, and localizes mainly in the mitochondria of both HT29 and HEP3B cells, whereas the cellular distribution of a protoporphyrin derivative with four amine moieties is not as specific.