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Emissive push–pull‐type bisnaphthyridylamine derivatives (BNA‐X: X=Me, Et, Bzl, Ph, BuBr, and BuTEMPO) aggregate in aqueous methanol. Furthermore, a two‐step emission and aggregation process is controllable by varying the methanol‐to‐water ratio. At 2:3 MeOH/H2O, crystallization‐induced emission enhancement (CIEE) occurs via formation of an emissive crystal phase, whereas, at 1:9 MeOH/H2O, aggregation‐induced emission enhancement (AIEE) occurs, induced by emissive supramolecular nanoparticles (NPs). For BNA‐Ph, the emission quantum yield was 25 times higher in aqueous methanol than that in pure methanol. Despite the high hydrophobicity of BNA‐X (C log P=6.1–8.0), the spherical NPs were monodisperse (polydispersity indices <0.2). Moreover, the emissive NPs exhibited fluorescence resonance energy transfer (FRET) with pyrene; however, for BNA‐X bearing the TEMPO radical (BNA‐BuTEMPO), no FRET was observed because of quenching. In particular, the BNA‐BuTEMPO NPs have a slow rotational correlation time (1.3 ns), suggesting applications as magnetic resonance imaging contrast agents with large relaxivity. [ABSTRACT FROM AUTHOR]

In our bodies, a slight pH change causes remarkable activation or serious damage in the biological processes and continuously keeps biological homeostasis. Detection of such a slight pH change has been a constant demand in searching for unusual biological events. In this paper, we demonstrate a novel pH sensory system that has been achieved through a combination of charge neutralization by a slight pH change with aggregation-induced emission (AIE). We selected a cyano-functionalized oligo(phenylene-vinylene) (cyanoOPV) backbone for AIE and introduced ammonium-tethered boronic acid groups as a pH-dependent function. The self-assembling of these dyes ( OPV-Cn) was readily achieved by pH-dependent charge neutralization at the neutral pH region. This sensory system showed unusually sensitive pH responsiveness in a narrow pH range. Moreover, this pH change was observed in a biologically important neutral pH region. We therefore believe that this system is broadly applicable to detect the slight pH change occurring in the biological events. [ABSTRACT FROM AUTHOR]

The newly developed oligophenylenevinylene (OPV)-based fluorescent (FL) chiral chemosensor (OPV-Me) for the representative enantiomeric guest, 1,2-cyclohexanedicarboxylic acid (1,2-CHDA: RR- and SS-form) showed the high chiral discrimination ability, resulting in the different aggregation modes of OPV-Me self-assembly: RR-CHDA directed the fibrous supramolecular aggregate, whereas SS-CHDA directed the finite aggregate. The consequent FL intensity toward RR-CHDA was up to 30 times larger than that toward SS-CHDA. Accordingly, highly enantioselective recognition was achieved. Application to the chirality sensing was also possible: OPV-Me exhibited a linear relationship between the FL intensity and the enantiomeric excess through the morphological development of stereocomplex aggregates. These results clearly show that the chiral recognition ability is manifested by the amplification cascade of the chirality difference through self-assembly. [ABSTRACT FROM AUTHOR]

The control over supramolecular interactions and obtaining information beyond the molecular scale is an extended challenge. The intriguing self-assembly of a perylene-3,4,9,10-tetracarboxylic acid diimide (PDI)-based novel bolaamphiphilic probe is experienced within an artificial environment that is restrained by using supramolecular crystallization and molecular recognition. The bolaamphiphile with a hydrophilic [18]-azacrown ether ring produced nanoaggregates due to differing solubilities in organic and aqueous media. A structural evolution was observed in the presence of alkali metal ions as guests. The metal complexes form a pseudo-cationic structure, which is further involved in an ionic self-assembly with biomolecules, thus resulting new spectroscopic information on the dye self-assembly. The overarching aim of this study is to emphasize the importance of the concept of supramolecular adaptability, which has been used to establish an environment-friendly behavior based on noncovalent forces, thus leading to the evolution of new assembly structures and photophysical properties. [ABSTRACT FROM AUTHOR]

Oligophenylenevinylene (OPV)-based fluorescent (FL) chemosensors exhibiting linear FL responses toward polyanions were designed. Their application to FL sensing of glycosaminoglycans (heparin: HEP, chondroitin 4-sulfate: ChS, and hyaluronic acid: HA) revealed that the charge density encoded as the unit structure directs the mode of OPV self-assembly: H-type aggregate for HEP with 16-times FL increase and J-type aggregate for HA with 93-times FL increase, thus unexpectedly achieving the preferential selectivity for HA in contrast to the conventional HEP selective systems. We have found that the integral magnitude of three factors consisting of binding mechanism, self-assembly, and FL response can amplify the structural information on the target input into the characteristic FL output. This emergent property has been used for a novel molecular recognition system that realizes unconventional FL sensing of HA, potentially applicable to the clinical diagnosis of cancer-related diseases. [ABSTRACT FROM AUTHOR]

Although self-assembly has realized the spontaneous formation of nanoarchitectures, the nanoscopic expression of chemical structural information at the molecular level can alternatively be regarded as a tool to translate molecular structural information with high precision. We have found that a newly developed guanidinium-tethered oligophenyle-nevinylene exhibits characteristic fluorescence (FL) responses toward l- and meso-tartarate, wherein the different self-assembly modes, termed J- or H-type aggregation, are directed according to the molecular information encoded as the chemical structure. This morphological difference originates from the geometric anti versus gauche conformational difference between l- and meso-tartarate. A similar morphological difference can be reproduced with the geometric C=C bond difference between fumarate and maleate. In the present system, the dicarboxylate structural information is embodied in the inherent threshold concentration of the FL response, the signal-to-noise ratio, and the maximum FL wavelength. These results indicate that self-assembly is meticulous enough to sense subtle differences in molecular information and thus demonstrate the potential ability of self-assembly for the expression of a FL sensory system. [ABSTRACT FROM AUTHOR]

A novel tetraphenylethene-based fluorescence (FL) chemosensor exhibits nonlinear turn-on FL switching though cooperative binding of L-tartarate, where its convergent binding to form cyclic substructures is responsible for the FL increase. This binding scheme achieves selective detection of dicarboxylates over monocarboxylates, thus is potentially applicable to the preliminary screening for metabolic disorders. [ABSTRACT FROM AUTHOR]

Hold and connect! Inclusion of a bridging ligand into cyclodextrin (CD), followed by the addition of TbIII leads to a polyrotaxane‐type metallosupramolecular polymer (see figure, L=4,4′‐biphenyldicarboxylic acid). This polymer can recognize chirality and differentiate enantiomers by fluorescence and circular dichroism spectral changes. [ABSTRACT FROM AUTHOR]

A fluorescent sensor based on guanidinium-tethered tetraphenylethene (TPE) has been investigated toward the differentiation of pyridine nucleotide cofactors (NAD+, NADH, NADP+, and NADPH). TPE selectively recognizes NADPH possessing the higher tetra-anionic net-charge, resulting in the steep 'turn-on' fluorescence increase. The comparative aggregation behaviors and fluorescence response studies of TPE on the four cofactors reveal that the critical aggregate concentration of TPE against NADPH correlates directly with the concentration threshold for the fluorescence response. These results establish that TPE can selectively differentiate NADPH over the other three cofactors by the steep aggregation-induced fluorescence response accompanied by the high signal-to-background contrast. [ABSTRACT FROM AUTHOR]

The vector control method is widely used for induction motor drives. In these applications, a rotational transducer such as a shaft encoder is used. A rotational transducer, however, cannot be mounted in some cases, such as motor drives in a hostile environment or high-speed motor drives. Several sensorless vector-controlled induction machine drive methods have been proposed. These methods have the disadvantage that rotor resistance variation causes errors in the estimation of the motor speed. It is difficult to estimate the motor speed and the rotor resistance simultaneously, because the equivalent rotor resistance is the ratio of the rotor resistance to the slip at steady state. Therefore, we have proposed a method of simultaneously estimating the motor speed and the rotor resistance of an induction motor by superimposing ac components on the field current command. This paper presents a modified method of the rotor resistance adaptation. The validity of the proposed method is verified by experiments. © 1998 Scripta Technica, Electr Eng Jpn, 125(2): 65–72, 1998 [ABSTRACT FROM AUTHOR]

Cover Feature: Push-Pull Bisnaphthyridylamine Supramolecular Nanoparticles: Polarity-Induced Aggregation and Crystallization-Induced Emission Enhancement and Fluorescence Resonance Energy Transfer (Chem. Eur. J. 9/2021) Keywords: emission; fluorescence; FRET; nanoparticles; radicals EN emission fluorescence FRET nanoparticles radicals 2885 2885 1 02/12/21 20210210 NES 210210 B An organic solution with a push-pull-type fluorophore b , which resembles the shape of a dragon in the cover image, exhibits aggregation-induced emission enhancement upon water addition. Emission, fluorescence, FRET, nanoparticles, radicals. [Extracted from the article]

Molecular Recognition Synergistic marriage of self‐assembly and fluorescence (FL) signaling has realized fluorometric readout of dicarboxylates. A newly developed guanidinium‐tethered oligophenylenevinylene (OPV‐G) exhibits characteristic self‐assembling behaviors toward L‐ and meso‐tartarate. Therein, the different self‐assembly modes termed J‐ and H‐type are directed to afford fibrous and finite aggregates, respectively. Such a difference derived from the inherent tartarate structures is eventually embodied as the unique FL responses. For more details, see the Full Paper by T. Noguchi, S. Shinkai et al. on page 13938 ff. [ABSTRACT FROM AUTHOR]