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Intramolecular catalyst transfer on benzoheterodiazoles was investigated in Suzuki–Miyaura coupling reactions and polymerization reactions with tBu3PPd precatalyst. In the coupling reactions of dibromobenzotriazole, dibromobenzoxazole, and dibromobenzothiadiazole with pinacol phenylboronate, the product ratios of monosubstituted product to disubstituted product were 0/100, 27/73, and 89/11, respectively, indicating that the Pd catalyst undergoes intramolecular catalyst transfer on dibromobenzotriazole, whereas intermolecular transfer occurs in part in the case of dibromobenzoxazole and is predominant for dibromobenzothiadiazole. The polycondensation of 1.3 equivalents of dibromobenzotriazole with 1.0 equivalent of para‐ and meta‐phenylenediboronates afforded high‐molecular‐weight polymer and cyclic polymer, respectively. In the case of dibromobenzoxazole, however, para‐ and meta‐phenylenediboronates afforded moderate‐molecular‐weight polymer with bromine at both ends and cyclic polymer, respectively. In the case of dibromobenzothiadiazole, they afforded low‐molecular‐weight polymers with bromine at both ends. Addition of benzothiadiazole derivatives interfered with catalyst transfer in the coupling reactions. [ABSTRACT FROM AUTHOR]

Radical‐type mechanophores (RMs) can undergo homolytic cleavage of their central C−C bonds upon exposure to mechanical forces, which affords radical species. Understanding the characteristics of these radical species allows bespoke mechanoresponsive materials to be designed and developed. The thermal stability of the central C−C bonds and the oxygen tolerance of the generated radical species are crucial characteristics that determine the functions and applicability of such RM‐containing mechanoresponsive materials. In this paper, we report the synthesis and characterization of two series of arylfluorene‐based RM derivatives, that is, 9,9'‐bis(5‐methyl‐2‐pyridyl)‐9,9'‐bifluorene (BPyF) and 9,9'‐bis(4,6‐diphenyl‐2‐triazyl)‐9,9'‐bifluorene (BTAF). BPyF and BTAF derivatives were synthesized without generating any peroxides initially, albeit that BPyF slowly converted to the corresponding peroxide in solution. DFT calculations revealed the importance of the thermodynamic stability and the values of the α‐SOMO levels of the corresponding radical species for their thermal stability and oxygen tolerance. Furthermore, the mechanochromism of BTAF was demonstrated by ball‐milling a BTAF‐centered polymer, which was synthesized by atom‐transfer radical polymerization (ATRP). [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are the groups of Hideyuki Otsuka at the Tokyo Institute of Technology and Koichiro Mikami at the Sagami Chemical Research Institute. The image depicts theoretical and experimental investigations of stable arylfluorene‐based radical‐type mechanophores. Read the full text of the article at 10.1002/chem.202203249. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are the groups of Hideyuki Otsuka at the Tokyo Institute of Technology and Koichiro Mikami at the Sagami Chemical Research Institute. The image depicts theoretical and experimental investigations of stable arylfluorene‐based radical‐type mechanophores. Read the full text of the article at 10.1002/chem.202203249. [ABSTRACT FROM AUTHOR]

The Suzuki–Miyaura coupling polymerization of p-dibromophenylene and m-phenylenediboronic acid ester, as well as m-dibromophenylene and p-phenylenediboronic acid ester, and the combination of two meta-phenylene monomers in the presence of the t-Bu3PPd(0) catalyst selectively afforded cyclic polyphenylenes with polyphenylene bearing boronate moieties at both ends when excess dibromophenylene was used. [ABSTRACT FROM AUTHOR]

Keywords: mechanochemistry; mechanochromism; mechanophores; polymers; radicals EN mechanochemistry mechanochromism mechanophores polymers radicals 1 1 1 02/28/23 20230224 NES 230224 B A human dive into the ocean of -SOMO levels b : Exhaled oxygen bubbles cause peroxidation of radical-type mechanophores (RMs), which generate shallow -SOMO level radical species; however, RMs that generate deep -SOMO level radical species did not afford peroxide compounds. Front Cover: Theoretical and Experimental Investigations of Stable Arylfluorene-Based Radical-Type Mechanophores (Chem. Eur. J. 12/2023) Mechanochemistry, mechanochromism, mechanophores, polymers, radicals. [Extracted from the article]

[Display omitted] Cyclic polymers bearing various backbones are selectively synthesized by means of non-stoichiometric Suzuki-Miyaura polycondensation of 1.0 equivalent of diboronate monomers containing carbon–carbon double bond (C=C), ester, ether, and carbonate linkages with 1.3 equivalents of meta - or para -dibromophenylene in the presence of t -Bu 3 PPd G2 precatalyst and CsF/18-crown-6 as a base. The molecular weight of the cyclic polymers increases with increasing monomer concentration. The obtained polymer containing C=C is cyclic even in the high-molecular-weight region, as confirmed by end-group analysis after degradative cross-metathesis reaction of the obtained polymer with an excess of an olefinic small molecule. This non-stoichiometric A 2 + B 2 Suzuki-Miyaura polycondensation is expected to be a powerful tool for the synthesis of cyclic polymers containing various functional groups in the backbone. [ABSTRACT FROM AUTHOR]

A seeding method, using colloidal amorphous silica seed made from geothermal fluid, has been tested as a silica scale prevention method. The effect on silica precipitation of the seed was examined experimentally. The results revealed correlations between the surface area and particle diameter of the seed and the mass of silica precipitated, and indicated that the seed exhibited highly reactive surface properties. The seed was confirmed to be of potential use as a silica removal reagent. Application of the seeding method to geothermal plants will guarantee the self-sufficiency of the latter as regards silica scale removal. [Copyright &y& Elsevier]

Suzuki–Miyaura coupling reaction of BrC6H4‐X‐C6H4Br 1 (X=CH2, CO, N‐Bu, O, S, SO, and SO2) with arylboronic acid 2 was investigated in the presence of tBu3PPd precatalyst and CsF/[18]crown‐6 as a base to establish whether or not the Pd catalyst can undergo catalyst transfer on these functional groups. In the reaction of 1 (X=CH2, CO, N‐Bu, O, and SO2) with 2, aryl‐disubstituted product 3 (Ar‐C6H4‐X‐C6H4‐Ar) was exclusively obtained, indicating that the Pd catalyst undergoes catalyst transfer on these functional groups. On the other hand, the reaction of 1 e (X=S) and 1 f (X=SO) with 2 afforded only aryl‐monosubstituted product 4 (Ar‐C6H4‐X‐C6H4‐Br) and a mixture of 3 and 4, respectively, indicating that S and SO interfere with intramolecular catalyst transfer. Furthermore, we found that Suzuki–Miyaura polycondensation of 1 (X=CH2, CO, N‐Bu, O, and SO2) and phenylenediboronic acid 5 in the presence of tBu3PPd precatalyst afforded high‐molecular‐weight polymer even when excess 1 was used. The polymers obtained from 1 (X=CH2, N‐Bu, and O) and 5 turned out to be cyclic. [ABSTRACT FROM AUTHOR]

Abstract: Mineral scales were formed in wells and surface installations during a 2-year circulation test performed at the Hijiori Hot Dry Rock (HDR) site, Yamagata, Japan. Anhydrite deposited in the deeper parts of the production wells, while silica and calcium carbonate precipitated at the surface, downstream of the wellhead, in amounts that depended on the temperature and chemical composition of the produced fluid. In well HDR-2a, closer to the injector, most of the scale was calcium carbonate; in HDR-3, further away from the injection well, there was slight precipitation of amorphous silica. As fluid circulation progressed and temperature decreased, scaling in the flow line of well HDR-2a changed from amorphous silica to calcium carbonate. [Copyright &y& Elsevier]

Mechanochromic elastomers that exhibit force‐induced cross‐linking reactions in the bulk state are introduced. The synthesis of segmented polyurethanes (SPUs) that contain difluorenylsuccinonitrile (DFSN) moieties in the main chain and methacryloyl groups in the side chains was carried out. DFSN was selected as the mechanophore because it dissociates under mechanical stimuli to form pink cyanofluorene (CF) radicals, which can also initiate the radical polymerization of methacrylate monomers. The obtained elastomers generated CF radicals and changed color by compression or extension; they also became insoluble due to the mechanically induced cross‐linking reactions. Additionally, an SPU containing diphenylmethane units also exhibited highly sensitive mechanofluorescence. To the best of our knowledge, this is the first report to demonstrate damage detection ability and changes in the mechanical properties of bulk elastomers induced by simple compression or extension. [ABSTRACT FROM AUTHOR]

Mechanochromic elastomers that exhibit force‐induced cross‐linking reactions in the bulk state are introduced. The synthesis of segmented polyurethanes (SPUs) that contain difluorenylsuccinonitrile (DFSN) moieties in the main chain and methacryloyl groups in the side chains was carried out. DFSN was selected as the mechanophore because it dissociates under mechanical stimuli to form pink cyanofluorene (CF) radicals, which can also initiate the radical polymerization of methacrylate monomers. The obtained elastomers generated CF radicals and changed color by compression or extension; they also became insoluble due to the mechanically induced cross‐linking reactions. Additionally, an SPU containing diphenylmethane units also exhibited highly sensitive mechanofluorescence. To the best of our knowledge, this is the first report to demonstrate damage detection ability and changes in the mechanical properties of bulk elastomers induced by simple compression or extension. [ABSTRACT FROM AUTHOR]

A non-symmetric radical-type mechanophore (CF/ABF) was synthesized by molecular crossing between two radical-type mechanophores. The thermal stability and mechanoresponsiveness of CF/ABF were found to be tunable by altering the properties of the parent RMs. The CF/ABF-centred polymers showed mixed mechanochromism derived from the simultaneous generation of two radical species. [ABSTRACT FROM AUTHOR]

Abstract: The leaching behavior of cathode ray tube (CRT) funnel glass containing 23 mass percent of Pb in 0.001N HCl, distilled water, and 0.001N NaOH at 90°C was investigated using a static method. The weight loss and leached amount of each component was measured and surface changes observed by SEM. The leaching mechanism is discussed. In acid solution, the leached amount of Pb showed t 1/2 dependence, that is, diffusion-controlled dependence, which is common in lead silicate glasses. In water and basic solutions, the leached amount showed saturation after higher initial dissolution than in acid and the deposition of many particles on the surface was observed. The amount leached was less for Pb than other components. The deposited particles formed a protective layer, which suppressed the dissolution of the glass. This dense layer must be formed as a result of a high initial dissolution rate. [ABSTRACT FROM AUTHOR]

Keywords: electron paramagnetic resonance; mechanochromism; polymer mechanochemistry; polyurethanes; self-strengthening EN electron paramagnetic resonance mechanochromism polymer mechanochemistry polyurethanes self-strengthening 8555 8555 1 04/01/21 20210406 NES 210406 B Mechanofunctional polymers b that exhibit color change, fluorescence, and self-strengthening ability were developed by Hideyuki Otsuka et al. in their Communication on page 8406. Electron paramagnetic resonance, mechanochromism, polymer mechanochemistry, polyurethanes, self-strengthening Inside Back Cover: Segmented Polyurethane Elastomers with Mechanochromic and Self-Strengthening Functions (Angew. [Extracted from the article]

Electron paramagnetic resonance, mechanochromism, polymer mechanochemistry, polyurethanes, self-strengthening Innenrücktitelbild: Segmented Polyurethane Elastomers with Mechanochromic and Self-Strengthening Functions (Angew. Keywords: electron paramagnetic resonance; mechanochromism; polymer mechanochemistry; polyurethanes; self-strengthening EN electron paramagnetic resonance mechanochromism polymer mechanochemistry polyurethanes self-strengthening 8639 8639 1 04/01/21 20210406 NES 210406 B Mechanofunktionelle Polymere b , die einen Farbwechsel, Fluoreszenz und die Fähigkeit zur Selbstverfestigung aufweisen, werden von Hideyuki Otsuka et al. in ihrer Zuschrift auf S. 8487 vorgestellt. [Extracted from the article]

In this study, we report the synthesis of dithieno[2,3- d :2′,3′- d ']anthra[1,2- b :5,6- b ']dithiophene (DTADT) unit and donor-acceptor (D-A) conjugated copolymers incorporated with the DTADT unit as the repeating unit. The novel oligoheteroacene unit––DTADT––was synthesized through the [2+2+2] annulation, which is the key reaction, and its reaction pathway was theoretically revealed using the density functional theory calculation. The D-A conjugated copolymers, synthesized through the transition metal-catalyzed polycondensation, could be applied as a solution-processable thin-film transistor. The our own n-layered integrated molecular orbital and molecular mechanics calculation in conjunction with the second order perturbation theory, analyzed based on the natural bond orbital analysis, unveiled that the steric repulsion among the side chains of DTADT and thiophene spacer kept away from the planarization of polymers; this affected the hole mobility of organic field-effect transistor. Image 1 • We established a synthetic route for DTADT unit and D-A copolymers, into which the novel heteroacene unit was embedded, and tested their application in solution-processable organic thin-film devices, which operate as a p-type transistor. • The DFT study unveiled that the theoretical reaction pathway of base-promoted [2 + 2+2] annulation is the key reaction for the synthesis of DTADT. • ONIOM and NBO studies unveiled that the side chain of the thiophene ring kept away from the planarization of polymers. [ABSTRACT FROM AUTHOR]