Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

Helical carbazole‐based BODIPY analogues were readily synthesized via aza[7]helicenes. The structures of azahelicene‐incorporated BF₂ dyes were elucidated by x‐ray diffraction analysis. DFT calculations revealed that the π‐conjugated system expanded from the helicene moiety to the BODIPY framework. The azahelicene‐fused boron complexes showed the Cotton effects and the circularly polarized luminescence (CPL) in the visible region. Furthermore, an axially chiral binaphthyl group was attached to the helically chiral dyes, which enhanced the chiroptical properties.

DOI： 10.1002/anie.202001186

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DOI： 10.1002/anie.201409729

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DOI： 10.1002/anie.201101864

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10847-026-01328-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Basic 1,3-azole-directed C(sp³)–H borylation is challenging due to potential catalyst deactivation and the CN bond reduction with pinacolborane (HBpin) generated during borylation with B₂(pin)₂.

DOI： 10.1039/d5cc03115j

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.orglett.5c01670

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Isocoumarins are an important class of bicyclic lactones, which are seen in natural products, drugs, and bioactive compounds, and a variety of synthetic methods of isocoumarins have been developed. However, the synthesis of isocoumarins via the catalytic CO2 fixation has been scarcely reported despite the potential incorporation of CO2 into the lactone moiety. Here, we developed the light‐driven carboxylative cyclization reaction of o‐ethynyl aryl bromides with CO2, which selectively produced isocoumarins. Control experiments revealed that photoirradiation promoted the cyclization process with high selectivity.

DOI： 10.1002/chem.202500563

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.macromol.4c02881

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<jats:title>Abstract</jats:title><jats:p>The Scholl reaction has been used to synthesize a variety of polycyclic aromatic hydrocarbons, where 1,2‐aryl shifts have sometimes occurred to yield unique rearrangement products. However, such 1,2‐aryl shifts are often uncontrollable, and the selective and divergent synthesis with or without rearrangement is desired. Here, we achieved the control of the rearrangement in the Scholl reaction of carbazoles by changing the <jats:italic>N</jats:italic>‐substituents. The Scholl reaction of 3,6‐bis{2‐(2‐naphthyl)phenyl}carbazoles and 3,6‐bis{2‐(9‐phenanthrenyl)phenyl}carbazoles with an <jats:italic>N</jats:italic>‐benzyl group gave multiple azahelicenes via double rearrangement, while those with an <jats:italic>N</jats:italic>‐benzoyl group gave aza[9]helicene and quadruple [4]helicene in the former and latter cases, respectively. The reaction mechanisms on the divergent reaction pathways were investigated by DFT calculations, which well supported the experimental results.</jats:p>

DOI： 10.1002/chem.202404325

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<jats:title>Abstract</jats:title>
<jats:p>Light-driven ring-opening carboxylation of epoxides with CO2 provided β-hydroxy acids via the sequential single electron transfer (SET), followed by the reaction with CO2. This reaction condition was applicable to aryl epoxides and oxetanes with (hetero)polycyclic aromatics to give the corresponding β- and γ-hydroxy acids, respectively, with the high chemoselectivity.</jats:p>

DOI： 10.1093/chemle/upae086

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Oxidative fusion reaction of cyclic heteroaromatic pentads consisting of pyrrole and thiophene gave closed‐heterohelicene monomers and dimers depending on the oxidation conditions. Specifically, oxidation with [bis(trifluoroacetoxy)iodo]benzene (PIFA) gave closed‐[7]helicene dimers connected at the β‐position of one of the pyrrole units with the remarkably elongated C–C bonds about 1.60 Å. Although this bond was intact against thermal and physical activations, homolytic bond dissociation took place upon UV irradiation in DMSO to give the corresponding monomers. Thus, interconversion between the closed‐helicene monomer and dimer was achieved. The optically pure dimer was photo‐dissociated into the monomers associated with circularly polarized luminescence (CPL) turn‐ON.

DOI： 10.1002/anie.202314968

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Bifunctional aluminum porphyrins catalyzed the terpolymerization of cyclohexene oxide (CHO), bis(CHO), and CO₂ to give cross-linked polycarbonates.

DOI： 10.1039/d3py00870c

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1039/D3OB00938F

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.orglett.3c01304

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：World Scientific Pub Co Pte Ltd  

Functional dyes showing circularly polarized luminescence (CPL) have attracted considerable attention. Porphyrins and porphyrinoids have characteristic properties useful for the development of CPL materials, although the examples of CPL-active porphyrins and porphyrinoids are still limited. Here we have summarized recent progress in CPL-active systems containing porphyrins or phthalocyanines, which are classified into the following four categories: (i) porphyrins with chiral sources; (ii) axially chiral porphyrin dimers; (iii) self-assembled porphyrins; (iv) porphyrin-sensitized CPL dyes.

DOI： 10.1142/s108842462330001x

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Abstract

Circularly polarized luminescence (CPL) dyes are recognized to be new generation materials and have been actively developed. Molecular recognition systems provide nice approaches to novel CPL materials, such as stimuli‐responsive switches and chemical sensing materials. CPL may be induced simply by mixing chiral or achiral, luminescent or nonluminescent host and guest; there are several combinations. Molecular recognition can potentially save time and effort to construct well‐ordered chiral structures with noncovalent attractive interactions as compared with the multi‐step synthesis of covalently bonded dyes. It is a challenging subject to engage molecular recognition events with CPL, and it is important and interesting to see how it is achieved. In fact, simple molecular recognition systems can even enable the fine adjustment of CPL performance and detailed conformational/configurational analysis of the excited state. Here we overview the recent achievements of simple host–guest complexes capable of exhibiting CPL, summarizing concisely the host/guest structures, CPL intensities, and characteristics.

DOI： 10.1002/chir.23522

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/chem.202102269

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

A variety of carbazolyl‐appended Schiff bases were readily synthesized from 1‐formylcarbazoles and aniline derivatives. Boron complexation of the resulting ligands allowed for facile preparation of new carbazole‐based BODIPY analogues showing solid‐state fluorescence. Furthermore, some dyes were converted into chiral compounds through the Et₂AlCl‐mediated incorporation of a binaphthyl unit. The chiral dyes showed aggregation‐induced fluorescence and circularly polarized luminescence (CPL) with the Φ_F and g_lum of up to 0.22 and −3.5×10⁻³, respectively, in the solid state. The solid‐state fluorescence and CPL were well characterized by the crystal packing analyses and DFT calculations.

DOI： 10.1002/chem.202001463

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Bifunctional AlIII porphyrins with quaternary ammonium halides, 2-Cl and 2-Br, worked as excellent catalysts for the copolymerization of cyclohexene oxide (CHO) and CO2 at 120 °C. Turnover frequency (TOF) and turnover number (TON) reached 10 000 h-1 and 55 000, respectively, and poly(cyclohexene carbonate) (PCHC) with molecular weight of up to 281 000 was obtained with a catalyst loading of 0.001 mol%. In contrast, bifunctional MgII and ZnII counterparts, 3-Cl and 4-Cl, as well as a binary catalyst system, 1-Cl with bis(triphenylphosphine)iminium chloride (PPNCl), showed poor catalytic performances. Kinetic studies revealed that the reaction rate was first-order in [CHO] and [2-Br] and zero-order in [CO2], and the activation parameters were determined: ΔH‡ = 12.4 kcal mol-1, ΔS‡ = -26.1 cal mol-1 K-1, and ΔG‡ = 21.6 kcal mol-1 at 80 °C. Comparative DFT calculations on two model catalysts, AlIII complex 2' and MgII complex 3', allowed us to extract key factors in the catalytic behavior of the bifunctional AlIII catalyst. The high polymerization activity and carbonate-linkage selectivity originate from the cooperative actions of the metal center and the quaternary ammonium cation, both of which facilitate the epoxide-ring opening by the carbonate anion to form the carbonate linkage in the key transition state such as TS3b (ΔH‡ = 13.3 kcal mol-1, ΔS‡ = -3.1 cal mol-1 K-1, and ΔG‡ = 14.4 kcal mol-1 at 80 °C).

DOI： 10.1039/d0sc01609h

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Abstract

A series of carbazole‐based boron dipyrromethenes (BODIPYs) 2 a–g bearing binaphthyl units have been synthesized by the Et₂AlCl‐mediated reaction of the corresponding BODIPY difluorides 1 a–g with 1,1′‐binaphthalene‐2,2′‐diol. Substituents such as halogen, nitrile, and amino groups were tolerated under the reaction conditions, and the reaction of the phenylethynyl‐substituted 1 h gave (R,R)‐3 h bearing two binaphthyl units. The chiroptical properties of these dyes with different substituents were investigated by UV/Vis, CD, fluorescence, and circularly polarized luminescence (CPL) spectroscopy. The CD spectra showed Cotton effects in the absorption region of the BODIPY moieties. In addition, they showed CPL both in solution and in the solid state. Interestingly, several dyes recorded higher g_lum values in the solid state, probably due to intermolecular interactions. Because (R,R)‐3 h recorded relatively low g_lum values, the diastereomer (R,S)‐3 h was prepared. The (R,S) diastereomer showed intense CPL, which suggests a synergetic effect of the two binaphthyl groups. Finally, chiral carbazole‐based BODIPY dimers have been synthesized for the first time and their chiroptical properties were investigated. They showed redshifted fluorescence and CPL, which reached the near‐IR (NIR) region in the solid state.

DOI： 10.1002/chem.201904954

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：World Scientific Pub Co Pte Lt  

DOI： 10.1142/s1088424619500937

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>A highly conjugated carbazole-based fused diporphyrin shows NIR absorption.</p>

DOI： 10.1039/d0cc06289h

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DOI： 10.1039/c9cc05079e

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Chiral binaphthyl-strapped Zn(II) porphyrins with triazolium halide units were synthesized as bifunctional catalysts for kinetic resolution of epoxides with CO2. Several catalysts were screened by changing the linker length and nucleophilic counteranions, and the optimized catalyst accelerated the enantioselective reaction at ambient temperature to produce optically active cyclic carbonates and epoxides.

DOI： 10.1021/acs.orglett.9b00447

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Chiral carbazole-based BODIPYs with a binaphthyl unit were synthesized via an Al-mediated reaction. Et2AlCl was found to be a convenient reagent for the reaction to give the chiral BODIPYs in high yields. It has been shown for the first time that these chiral carbazole-based BODIPYs show circularly polarized luminescence (CPL) both in solution and in the solid state.

DOI： 10.1039/c9cc00894b

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Doubly (R)-binaphthyl-strapped porphyrins with methylene chains were synthesized. The CD spectra showed the positive Cotton effect around the Soret bands, and several porphyrins showed CPL. In addition, we found that the chiral porphyrins were applicable to kinetic resolution of epoxide with CO2.

DOI： 10.1039/c8cc09114e

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

DOI： 10.1039/c8cy00941d

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Annulation reactions of the butadiyne-bridged carbazole dimer 1 produced carbazole-based chalcogenaisophlorins 2-4, which were transformed into the corresponding palladium complexes 2Pd-4Pd. The structures were characterized by NMR spectroscopy and X-ray diffraction analysis. Metallation fixed the structures which displayed weak antiaromatic character derived from the 20π isophlorin framework. These complexes showed weak near-infrared (NIR) absorption typical for antiaromatic porphyrinoids in solution. In addition, 2Pd and 3Pd showed relatively strong solid-state NIR absorption. X-ray diffraction analyses of 2Pd and 3Pd revealed trimeric and dimeric stacked layered structures, respectively, and DFT calculations suggest that the solid-state NIR absorption is ascribed to intermolecular charge transfer.

DOI： 10.1002/cplu.201700430

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DOI： 10.1039/c7ob02419c

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DOI： 10.1039/c7ob01473b

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DOI： 10.1021/acs.orglett.6b03054

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Highly active bifunctional metalloporphyrin catalysts were developed for the coupling reaction of epoxides with CO2 to produce cyclic carbonates. The bifunctional catalysts have both quaternary ammonium halide groups and a metal center. To elucidate the roles of these catalytic groups, DFT calculations were performed. Control reactions using tetrabutylammonium halide as a catalyst were also investigated for comparison. In the present article, the results of our computational studies are overviewed. The computational results are consistent with the experimental data and are useful for elucidating the structure-activity relationship. The key features responsible for the high catalytic activity of the bifunctional catalysts are as follows: 1) the cooperative action of the halide anion (nucleophile) and the metal center (Lewis acid); 2) the near-attack conformation, leading to the efficient opening of the epoxide ring in the rate-determining step; and 3) the conformational change of the quaternary ammonium cation to stabilize various anionic species generated during catalysis, in addition to the robustness (thermostability) of the catalysts.

DOI： 10.1002/tcr.201600053

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Language：Japanese  

DOI： 10.5059/yukigoseikyokaishi.74.814

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DOI： 10.1021/jacs.6b06328

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

Several carbazole‐based boron dipyrromethene (BODIPY) dyes were synthesized by organometallic approaches. Thiazole, benzothiazole, imidazole, benzimidazole, triazole, and indolone substituents were introduced at the 1‐position of the carbazole moiety, and boron complexation of each dipyrrin generated the corresponding compounds 1, 2 a, and 3–6. The properties of these products were investigated by UV/Vis and fluorescence spectroscopy, cyclic voltammetry, X‐ray crystallography, and DFT calculations. These compounds exhibited large Stokes shifts, and compounds 1, 2 a, and 3–5 fluoresced both in solution and in the solid state. Complex 2 a showed the highest fluorescence quantum yield (Φ_F) in the solid state, therefore boron complexes of the carbazole–benzothiazole hybrids 2 b–f, which had several different substituents, were prepared and the effects of the substituents on the photophysical properties of the compounds were examined. The fluorescence properties showed good correlation with the results of crystal‐packing analyses, and the dyes exhibited color‐tunable solid‐state fluorescence.

DOI： 10.1002/chem.201505150

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Abstract

Bifunctional metalloporphyrins with quaternary ammonium bromides (nucleophiles) at the meta, para, or ortho positions of meso‐phenyl groups were synthesized as catalysts for the formation of cyclic carbonates from epoxides and carbon dioxide under solvent‐free conditions. The meta‐substituted catalysts exhibited high catalytic performance, whereas the para‐ and ortho‐substituted catalysts showed moderate and low activity, respectively. DFT calculations revealed the origin of the advantage of the meta‐substituted catalyst, which could use the flexible quaternary ammonium cation at the meta position to stabilize various anionic species generated during catalysis. A zinc(II) porphyrin with eight nucleophiles at the meta positions showed very high catalytic activity (turnover number (TON)=240 000 at 120 °C, turnover frequency (TOF)=31 500 h⁻¹ at 170 °C) at an initial CO₂ pressure of 1.7 MPa; catalyzed the reaction even at atmospheric CO₂ pressure (balloon) at ambient temperature (20 °C); and was applicable to a broad range of substrates, including terminal and internal epoxides.

DOI： 10.1002/chem.201600164

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DOI： 10.1039/c5ob01824b

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DOI： 10.1021/acs.orglett.5b01363

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DOI： 10.1021/ja507665a

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DOI： 10.1039/c3ob42564a

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DOI： 10.1039/c3cy00993a

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DOI： 10.1021/ol401403n

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DOI： 10.1002/chem.201202573

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DOI： 10.1021/ol303392g

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DOI： 10.1021/ol300585v

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DOI： 10.1039/c2ob25645b

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DOI： 10.1039/c2cc30834g

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DOI： 10.1002/chem.201100872

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DOI： 10.1002/chem.200903195

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DOI： 10.1021/ol100448x

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DOI： 10.1021/ol902294r

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DOI： 10.1002/chem.200901475

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DOI： 10.1021/ol7028299

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DOI： 10.1016/j.ccr.2007.02.017

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DOI： 10.1021/ol070885k

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DOI： 10.1039/b515740d

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Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京田辺  

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Event date： 2015.10

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Venue：つくば  

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Event date： 2015.8

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Venue：台湾  

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Event date： 2013.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Cheju, Korea  

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Event date： 2025.6

Presentation type：Poster presentation  

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