start-ver=1.4
cd-journal=joma
no-vol=61
cd-vols=
no-issue=25
article-no=
start-page=4757
end-page=4773
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2025
dt-pub=2025
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Recent development of azahelicenes showing circularly polarized luminescence
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Recently, a variety of circularly polarized luminescence (CPL) dyes have been developed as next-generation chiroptical materials. Helicenes, ortho-fused aromatics, have been recognized as some of the most promising CPL dyes. Although typical carbohelicenes show CPL, weak fluorescence is often emitted in the blue region. In contrast, heteroatom-embedded helicenes (heterohelicenes) can show intense fluorescence and CPL in the visible region because heteroatoms alter the electronic states of helicene frameworks. Among various heterohelicenes, nitrogen-embedded helicenes (azahelicenes) have unique features such as facile functionalization and sensitive responses to acid/base or metal ions. Furthermore, polycyclic aromatic hydrocarbons (PAHs) containing azaborine units have been recognized as excellent luminescent materials, and the helical derivatives, B,N-embedded helicenes, have been rapidly growing recently. In this feature article, we review and summarize the synthesis and chiroptical properties of azahelicenes, which are classified into imine-type and amine-type azahelicenes and B,N-embedded helicenes. CPL switching systems of azahelicenes are also reviewed.
en-copyright=
kn-copyright=

en-aut-name=MaedaChihiro
en-aut-sei=Maeda
en-aut-mei=Chihiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=EmaTadashi
en-aut-sei=Ema
en-aut-mei=Tadashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

affil-num=1
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=2
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=64
cd-vols=
no-issue=8
article-no=
start-page=e202418546
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2025
dt-pub=20250122
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=B,N‐Embedded Helical Nanographenes Showing an Ion‐Triggered Chiroptical Switching Function
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Intramolecular oxidative aromatic coupling of 3,6-bis(m-terphenyl-2’-yl)carbazole provided a bis(m-terphenyl)-fused carbazole, while that of 3,6-bis(m-terphenyl-2’-yl)-1,8-diphenylcarbazole afforded a bis(quaterphenyl)-fused carbazole. Borylation of the latter furnished a B,N-embedded helical nanographene binding a fluoride anion via a structural change from the three-coordinate boron to the four-coordinate boron. The anionic charge derived from the fluoride anion is stabilized over the expanded π-framework, which leads to the high binding constant (Ka) of 1×105 M−1. The four-coordinate boron species was converted back to the parent three-coordinate boron species with Ag+, and the chiroptical switch between the three-coordinate boron and four-coordinate boron species has been achieved via the ion recognition with the change in the color and glum values.
en-copyright=
kn-copyright=

en-aut-name=MaedaChihiro
en-aut-sei=Maeda
en-aut-mei=Chihiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=MichishitaSayaka
en-aut-sei=Michishita
en-aut-mei=Sayaka
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=YasutomoIssa
en-aut-sei=Yasutomo
en-aut-mei=Issa
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=EmaTadashi
en-aut-sei=Ema
en-aut-mei=Tadashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

affil-num=1
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=2
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=3
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=4
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=
en-keyword=Boron
kn-keyword=Boron
en-keyword=Chirality
kn-keyword=Chirality
en-keyword=Circularly polarized luminescence
kn-keyword=Circularly polarized luminescence
en-keyword=Helical nanographenes
kn-keyword=Helical nanographenes
en-keyword=Ion sensing
kn-keyword=Ion sensing
END

start-ver=1.4
cd-journal=joma
no-vol=14
cd-vols=
no-issue=37
article-no=
start-page=4338
end-page=4343
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2023
dt-pub=2023
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Catalytic synthesis and physical properties of CO2-based cross-linked poly(cyclohexene carbonate)s
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Bifunctional aluminum porphyrins (0.001 mol%) catalyzed the terpolymerization of cyclohexene oxide (CHO), bis(CHO), and CO2 to give cross-linked polycarbonates (CLPs) under solvent-free conditions. A small amount of bis(CHO) acted as a cross-linking agent, and the use of only 0.1 mol% bis(CHO) to CHO produced polymers of quite large sizes. The thermal and mechanical properties of CLPs could be altered by changing the structure and amount of bis(CHO), and the CLPs showed improved thermal stability and tensile strength as compared to linear poly(cyclohexene carbonate)s (PCHCs). The degradation of the CLPs was also investigated, and the selective cleavage of the cross-links was achieved by UV light irradiation to give linear PCHCs. The present study disclosed the potentials of cross-linking terpolymerization for the preparation of various CLPs with a constant CO2 content (31 wt%).
en-copyright=
kn-copyright=

en-aut-name=MaedaChihiro
en-aut-sei=Maeda
en-aut-mei=Chihiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=KawabataKenta
en-aut-sei=Kawabata
en-aut-mei=Kenta
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=NikiKaito
en-aut-sei=Niki
en-aut-mei=Kaito
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=SakoYuma
en-aut-sei=Sako
en-aut-mei=Yuma
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=OkiharaTakumi
en-aut-sei=Okihara
en-aut-mei=Takumi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=EmaTadashi
en-aut-sei=Ema
en-aut-mei=Tadashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

affil-num=1
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=2
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=3
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=4
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=5
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=6
en-affil=Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
kn-affil=
END

start-ver=1.4
cd-journal=joma
no-vol=11
cd-vols=
no-issue=22
article-no=
start-page=5669
end-page=5675
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=20200518
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Aluminum porphyrins with quaternary ammonium halides as catalysts for copolymerization of cyclohexene oxide and CO2: metal–ligand cooperative catalysis
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=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).
en-copyright=
kn-copyright=

en-aut-name=DengJingyuan
en-aut-sei=Deng
en-aut-mei=Jingyuan
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=RatanasakManussada
en-aut-sei=Ratanasak
en-aut-mei=Manussada
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=SakoYuma
en-aut-sei=Sako
en-aut-mei=Yuma
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=TokudaHideki
en-aut-sei=Tokuda
en-aut-mei=Hideki
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
ORCID=

en-aut-name=MaedaChihiro
en-aut-sei=Maeda
en-aut-mei=Chihiro
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=5
ORCID=

en-aut-name=HasegawaJun-ya
en-aut-sei=Hasegawa
en-aut-mei=Jun-ya
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=6
ORCID=

en-aut-name=NozakiKyoko
en-aut-sei=Nozaki
en-aut-mei=Kyoko
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=7
ORCID=

en-aut-name=EmaTadashi
en-aut-sei=Ema
en-aut-mei=Tadashi
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=8
ORCID=

affil-num=1
en-affil=Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo
kn-affil=

affil-num=2
en-affil=Institute for Catalysis, Hokkaido University
kn-affil=

affil-num=3
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=4
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=5
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=

affil-num=6
en-affil=Institute for Catalysis, Hokkaido University
kn-affil=

affil-num=7
en-affil=Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo
kn-affil=

affil-num=8
en-affil=Graduate School of Natural Science and Technology, Okayama University
kn-affil=
END