Photobase-Driven Excited-State Intramolecular Proton Transfer (ESIPT) in a Strapped π-Electron System

We report a new design strategy for an excited-state intramolecular proton transfer (ESIPT) fluorophore that can be used in acidic media. A photobasic pyridine-centered donor-acceptor-donor-type fluorophore is combined with a basic trialkylamine “strap”. In the presence of an acid, protonation occurs predominantly at the amine moiety in the ground state. A single-crystal X-ray diffraction analysis confirmed the formation of a pre-organized intramolecular hydrogen-bonded structure between the resulting ammonium moiety and the pyridine ring. Upon excitation, the intramolecular charge-transfer transition increases the basicity of the pyridine moiety in the excited state, resulting in proton transfer from the amine to the pyridine moiety. Consequently, the fluorophore takes on a polymethine-dye character in the ESIPT state, which gives rise to significantly red-shifted emission with an increased fluorescence quantum yield.     

Development of a new amblyopia-training device with polarizing films used under binocular conditions

Optical Review - We developed an amblyopia-training device, which can be used easily and inexpensively under binocular conditions with polarizing films. The device uses two polarizing films: one is...     

Synthesis and Electronic Properties of Directly Linked Dihydrodiazatetracene Dimers

5,12-Dihydro-5,12-diazatetracene (DHDAT) dimers with different substitution patterns are synthesized: a symmetric one with a C−C bond between the monomer units ( 1 ) and two asymmetric ones with a C−N bond between the monomer units ( 2 and 3 ). The DHDAT units are planar in the C−C linked dimer 1 but perpendicularly oriented in the C−N linked dimers 2 and 3 (from X-ray analysis). The electronic ground-state interaction between the two units is large in 1 and small in 2 and 3 . The emission behavior of 3 is different from that of other dimers and its monomer; it displays positive solvatochromism, characteristic for electron donor–acceptor molecules, despite its donor–donor type structure. Compound 3 exhibits a unique multi-step thermochromic emission behavior. The emission behavior is attributed to the asymmetric distribution of the HOMO and LUMO of DHDAT.     

Primary Sulfonamide Functionalization via Sulfonyl Pyrroles: Seeing the N−Ts Bond in a Different Light

Despite common occurrence in molecules of value, methods for transforming sulfonamides are distinctly lacking. Here we introduce easy-to-access sulfonyl pyrroles as synthetic linchpins for sulfonamide functionalization. The versatility of the sulfonyl pyrrole unit is shown by generating a variety of products through chemical, electrochemical and photochemical pathways. Preliminary results on the direct functionalization of primary sulfonamides are also provided, which may lead to new modes of activation.     

Tetrathienyl Corannulene Compounds with Highly Sensitive Photochromism

We have designed and synthesized photochromic tetrathienyl corannulene compounds, 1,2,7,8-tetrakis(2-methyl-5-phenylthiophen-3-yl)corannulene ( 1 ) and 1,2,7,8-tetrakis(2,4-dimethyl-5-phenylthiophen-3-yl)corannulene ( 2 ), by fusing two units of photochromic terarylene with a curved aromatic corannulene with a promising antenna effect. Compound 1 exhibited highly sensitive photoreactivity, with a large molar absorption coefficient of 8.2×10⁴ M⁻¹ cm⁻¹ and practically photon-quantitative photocyclization. On the other hand, a terarylene derivative with a planar aromatic phenanthrene, 9,10-bis(2,4-dimethyl-5-phenylthiophen-3-yl)phenanthrene ( 4 ) showed no photoreactivity. The reason for such a difference was attributed to the predominance of the photoreactive atropisomers amplified by energy migration, and the shortened distance between reactive carbons induced by the curved structure.     

Synthesis,Structure, and Dynamics of Chiral Eight-Membered Cyclic Molecules with Thienylene and Cyclopropylene Units Alternately Connected

A rhodium(II)-catalyzed asymmetric cyclooligomerization of bifunctional monomers possessing triazolyl and vinyl groups at 2,3- and 3,4-positions on the thiophene ring is studied. Structurally interesting cyclic dimers in which thienylene and cyclopropylene units are alternately connected are obtained as the major components. The eight-membered rings in the center are non-planar and adopt a tub-shaped conformation. We also observe the phenomenon of racemization caused by a tub-to-tub ring-flipping, the activation energy of which is determined as 108 kJ mol⁻¹ by electronic circular dichroism spectra measurement.     

Facile aerobic photo-oxidative synthesis of α-diketones from alkynes

We report a useful method for facile aerobic photo-oxidative synthesis of α-diketones from alkynes with MgBr₂·OEt₂. This procedure provides a practical synthetic method of α-diketones using easily handled bromine sources, harmless visible light, and molecular oxygen as terminal oxidant.     

A remark on the Schrödinger propagator on Wiener amalgam spaces

In this paper, we study the boundedness of the Schrödinger propagator on Wiener amalgam spaces. In particular, we determine the necessary and sufficient conditions for the propagator to be bounded from to .     

Crosslinked copolymer with low dielectric constant and dissipation factor based on poly(2,6‐Dimethylphenol‐co−2,6‐Diphenylphenol) and a crosslinker

The crosslinked poly(2,6‐dimethylphenol (95 mol %)‐co?2,6‐diphenylphenol (5 mol %)) (poly(2,6‐DMP₉₅‐co?2,6‐DPP₅)) was successfully developed as an insulating material separating conducting elements with a low dielectric constant and dissipation factor. The crosslinked poly(2,6‐DMP₉₅‐co?2,6‐DPP₅) was prepared by the oxidative coupling polymerization of 2,6‐DMP with 2,6‐DPP, followed by the reaction with 4,4′‐methylenebis[2,6‐bis(methoxymethyl)]phenol (MBMP) as a crosslinking agent. The crosslinked poly(2,6‐DMP₉₅‐co?2,6‐DPP₅) exhibited a good thermal stability and glass transition temperature. The dielectric constant and dissipation factor of the crosslinked poly(2,6‐DMP₉₅‐co?2,6‐DPP₅) were 2.6 and 0.004 at 10 GHz, respectively. Moreover, a flexible double layer copper clad laminate based on the crosslinked poly(2,6‐DMP₉₅‐co?2,6‐DPP₅) composite was successfully prepared, indicating a useful material for high‐speed and high‐frequency electrical applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3218–3223