Mechanochromic Delayed Fluorescence Switching in Propeller‐Shaped Carbazole–Isophthalonitrile Luminogens with Stimuli‐Responsive Intramolecular Charge‐Transfer Excited States

Herein, the universal design of high‐efficiency stimuli‐responsive luminous materials endowed with mechanochromic luminescence (MCL) and thermally activated delayed fluorescence (TADF) functions is reported. The origin of the unique stimuli‐triggered TADF switching for a series of carbazole–isophthalonitrile‐based donor–acceptor (D–A) luminogens is demonstrated based on systematic photophysical and X‐ray analysis, coupled with theoretical calculations. It was revealed that a tiny alteration of the intramolecular D–A twisting in the excited‐state structures governed by the solid morphologies is responsible for this dynamic TADF switching behavior. This concept is applicable to the fabrication of bicolor emissive organic light‐emitting diodes using a single TADF emitter.     

Double-Heterostructure Indium-Tin Oxide/InGaAsP/AlGaAs Lasers

The fabrication and characterization of double-heterostructure (DH) laser that utilizes an indium-tin oxide (Ito) transparent cladding and top contact layer. The first room-temperature lasing operation has been obtained form ITO/InGaAsP/AlGaAs DH laser diode at threshold current density of 12.1 kA/cm². The interfacial recombination velocity of ITO/InGaAsP Interface was estimated to be 4.9 × 10⁴ cm/s from a simple model to account for high threshold current, and optical measurements of spontaneous emission and lasing spectra from top stripe window and facet were done.     

Quiescent hydrothermal synthesis of reduced graphene oxide–periodic mesoporous silica sandwich nanocomposites with perpendicular mesochannel alignments

Quiescent hydrothermal conditions were applied to synthesis of the sandwich nanocomposites of reduced graphite oxide (rGO) and periodic mesoporous silica (PMS) with vertically aligned mesochannels. It was found that the formation of the PMS–rGO–PMS sandwich structure is very sensitive to the surface and synthesis conditions. Although a higher temperature hydrothermal condition promotes reduction of GO and formation of bulky mesoporous nanoparticles, quiescent hydrothermal condition can serve as an alternative approach to obtain the unusual nanocomposites and slightly promote the structural stability of PMS on the surface of rGO.     

Quantitative analysis of inhomogeneous luminance effect on visibility of text

In the present study, we measured the visibility of several types of Japanese text on a liquid crystal display (LCD) with a spatially inhomogeneous luminance and extended the visibility index function (VIF) to explain the current experimental results with a higher degree of accuracy. We quantitatively analyzed the effect of an inhomogeneous luminance, which was produced by the graphical representation of a background without reflected light and by reflected light on a homogeneous background. These results showed that the visibility of text was influenced by the inhomogeneity of the background luminance in a domain that depended on text size. Then we applied a weighted average background luminance with a two dimensional Gaussian function, whose distribution width was related to the text size, to VIF. Finally, we proposed a modified VIF and showed that the new method was able to precisely estimate the actual visibility of text with an inhomogeneous luminance.     

Optical simulation of reduced retinal illuminance caused by senile miosis

In order to simulate elderly vision for young observers, we developed an optical goggle using filters whose transmittance optically simulates the senile miosis: reduction in retinal illuminance as a function of ambient illuminance. First, we measured the pupil size of young and elderly subjects (mean age were 21.8 and 67.1 years, respectively) under six illuminance conditions (from 0.03 to 4850 lx), and formulated the relationship between illuminance and pupillary area functions in both age groups. Next, the transmittance formulae for the filter simulating the senile miosis were derived based on the properties of the pupillary area and visual functions of the elderly and the young subjects including the effect of mydriasis induced by the reduction of light due to the filter in young observers. Finally, we developed a goggle-type simulator using active optical devices which enables young people to experience senile miosis in any environment in real time.     

Synthesis of water-soluble C60-porphyrin hybrid compounds

Water-soluble C60-porphyrin hybrid molecules were first synthesized toward their pharmaceutical applications.     

Dithienylethenes with a novel photochromic performance

Dithienylethenes with low decoloration quantum yields and thermal reversibility at high temperature above 100 degrees C were prepared. Introduction of bulky alkoxy substituents at 2- and 2'-positions of the thiophene rings strongly suppressed the cycloreversion quantum yields. The quantum yields were lower than 10(-3), and the photogenerated color remained stable enough under room light. On the other hand, the bulky alkoxy substituent decreased the thermal stability of the colored closed-ring isomers at high temperature. The color of the dithienylethene with cyclohexyloxy substituents faded out in less than 1 min at 160 degrees C.     

Asymmetric total synthesis of (-)-spirofungin A and (+)-spirofungin B

[chemical reaction: see text]. The stereocontrolled total synthesis of (-)-spirofungin A (1) and (+)-spirofungin B (2a), polyketide-type antibiotics having various antifungal activities, has been achieved employing the Weinreb amide 8, the alkyne 9, and the vinyl boronate 5 readily available from the common intermediate 10. The first synthesis proceeded with a longest linear sequence of 31 steps, affording (-)-1 and (+)-2a in 7.9% and 5.2% overall yields, respectively.     

An HPLC assay of hydroxyl radicals by the hydroxylation reaction of terephthalic acid

An HPLC assay for hydroxyl radicals is described. The hydroxyl radical was trapped by terephthalic acid (non-fluorescent), and 2-hydroxyl terephthalic acid (fluorescent) was quantitated by HPLC-fluorescence detection. At a terephthalic acid concentration of 4.25 mmol/L, the hydroxyl radical formed in the Fenton reaction was successfully assayed in the concentration range of hydrogen peroxide of 2.5-50 micro mol/L, where the concentration of Fe(II) was 50 micro mol/L. The fluorescence of 2-hydroxy terephthalate was stable at 24 h, and its detection limit by this method was 5 nmol/L (100 fmol).