Article
Polymer Science
Xing-Qi Yao, Yi-Song Wang, Jianbo Wang
Summary: The newly developed (Cp(π-allyl)Pd) initiating system efficiently synthesizes homo- and copolymers with ester substituents, tolerates various functional groups, and exhibits slow initiation and rapid propagation characteristics. Alcohols are found to function as chain transfer agents for controlling the molecular weight of the polymer.
Article
Polymer Science
Hiroaki Shimomoto, Hinano Hayashi, Kyoka Aramasu, Tomomichi Itoh, Eiji Ihara
Summary: Three new N-arylmaleimide-based Pd(0) complexes were synthesized and used as initiators for polymerization of diazoacetates. Experimental observations and mass spectrometry analysis revealed that the initiating species of the polymerization was generated by the insertion of N-arylmaleimide into a Pd-Ph linkage, and this method enables the synthesis of alpha-chain-end-functionalized polymers.
Article
Polymer Science
Rui Tan, Xiaochun Mu, Haiyang Wang, Yang Li
Summary: By using (i)Pr(2)Im as a Lewis base ligand, beta-H elimination reactions in propylene polymerization were suppressed, resulting in high molecular weight polypropylene and block copolymers. DFT calculations showed that the delocalized electrons in (i)Pr(2)Im could decrease the electro positivity of active sites, providing a convenient strategy for tuning their electronic properties.
Article
Chemistry, Multidisciplinary
Le Dung Pham, Red O. Smith-Sweetser, Briana Krupinsky, Carolyn E. Dewey, Jessica R. Lamb
Summary: This study demonstrates that NHC-CDI adducts can be used as masked precursors for switchable organocatalysis, and the CDI substituents can control the reaction profile without changing the NHC structure. By controlling the electronic variations and perturbations on the CDI, the catalytically active temperature and catalyst release range can be controlled.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Polymer Science
Hiroaki Shimomoto, Yuto Miyano, Kaito Kinoshita, Tomomichi Itoh, Eiji Ihara
Summary: A series of Pd complexes with diphosphines or diamines and dichloroquinone-derived units as ligands were synthesized and investigated for their initiation abilities in diazoacetate polymerization. It was found that (diphosphine)Pd(ii)Cl(Cl-quinonyl) complexes produced highly syndiotactic polymers, while (diamine)Pd(0)(dichloroquinone) complexes afforded moderately syndiotactic polymers. These findings demonstrate the potential of these complexes as initiating systems for stereoselective diazoacetate polymerization.
Article
Nanoscience & Nanotechnology
Yunsoo Choi, Chul Soon Park, Hung-Vu Tran, Chien-Hung Li, Cathleen M. Crudden, Randall Lee
Summary: This study reports the development and use of bench-stable NHC adsorbates for the direct formation of NHC films on gold surfaces under ambient conditions. The generated NHC SAMs were fully characterized and compared to analogous SAMs generated from a different adsorbate. Furthermore, the potential utility of these NHC films as surface-initiated polymerization platforms was demonstrated.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Qing-Zhu Li, Rong Zeng, Peng-Shuai Xu, Xin-Hang Jin, Chuan Xie, Qi-Chun Yang, Xiang Zhang, Jun-Long Li
Summary: In this study, a cross-coupling reaction of aldehydes with unactivated alkyl halides was developed through N-heterocyclic carbene catalysis, enabling the synthesis of various ketones. This method offers the advantages of mild reaction conditions and readily available starting materials, and has been successfully applied in the functionalization of pharmaceutical derivatives.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Qing-Zhu Li, Rong Zeng, Peng-Shuai Xu, Xin-Hang Jin, Chuan Xie, Qi-Chun Yang, Xiang Zhang, Jun-Long Li
Summary: Catalytic cross-coupling reaction of aldehydes with unactivated alkyl halides was achieved via N-heterocyclic carbene catalysis. This method enables rapid synthesis of various ketones from readily available starting materials under mild conditions. The organocatalytic system was successfully applied in the late-stage functionalization of pharmaceutical derivatives. Mechanistic investigations suggest a closed-shell nucleophilic substitution mechanism for this reaction.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Polymer Science
Kota Oto, Yuki Muramatsu, Akinori Takasu, Masahiro Higuchi
Summary: The combination of NHCtBu and MAD functioned as an interacting Lewis pair (ILP) for anionic polymerization of various acrylates. The ILP exhibited higher reactivity towards ethyl acrylate (EA) than n-butyl acrylate (n-BA) or t-butyl acrylate (t-BA). The slow initiation of n-BA and t-BA facilitated chain polymerization initiated by deprotonated methyl sorbate (MS) and subsequent ring-closure.
Article
Chemistry, Multidisciplinary
Nil Sanosa, Diego Ambrosi, Pedro Ruiz-Campos, Diego Sampedro, Ignacio Funes-Ardoiz
Summary: Formation of carbon-carbon bonds through cross-coupling reactions using readily available substrates, like alcohols, is crucial for modern organic chemistry. Recently, direct alkyl alcohol functionalization has been achieved by the use of N-Heterocyclic Carbene (NHC) salts via in situ formation of an alcohol-NHC adduct and its activation by a photoredox catalyst to generate carbon-centered alkyl radicals. Experimental observations show that only electron deficient NHC activators work, but the reasons for this behavior are not well understood. In this study, a DFT computational approach is used to investigate the mechanism of alcohol activation using up to seven NHC salts, providing insights into the influence of their electronic properties on alkyl radical formation. The results reveal that the electron-richness of the NHC salt plays a crucial role in determining the success of the transformation.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Polymer Science
Hiroaki Shimomoto, Itsuki Katashima, Hirokazu Murakami, Tomomichi Itoh, Eiji Ihara
Summary: Diazoacetates with various alkyl groups were polymerized to produce atactic poly(alkoxycarbonylmethylene)s (PACMs) using Pd-based initiating systems, and the effect of alkyl side-chain structure on thermophysical properties was investigated. It was found that using linear and branched side chains with different alkyl chain lengths did not significantly increase the melting point (T (m)) of PACMs. However, incorporating an amide-linkage in the middle of linear alkyl chains effectively raised T (m) due to hydrogen bonding interactions. The spacer length between the ester and amide linkages was crucial for increasing T (m), with the highest T (m) of around 130 degrees C achieved using a C4 spacer length and outer alkyl chain lengths of C7 and C9.
Review
Polymer Science
Isha Jain, Payal Malik
Summary: Metal-N-heterocyclic carbene complexes (M-NHCs) have shown great potential as a catalytic system for the synthesis of various biodegradable polymers via ring opening polymerization. This review provides an overview of the field's major achievements and developments from 2004 to 2020, with a focus on the structure-activity relationship of M-NHC complexes.
EUROPEAN POLYMER JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Hang Shen, Michael B. Larsen, Allison G. Roessler, Paul M. Zimmerman, Andrew J. Boydston
Summary: A new flex-activated mechanophore has been discovered, which releases an N-heterocyclic carbene (NHC) under mechanical load. This design demonstrates a promising first step towards flex-activated designs with downstream reactivities, allowing for iterative activation increases in the material through non-destructive compression cycles. The potential modularity of the mechanophore design is highlighted by the demonstration of two different NHC structures.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Zhen Li, Pengju Ji, Jin-Pei Cheng
Summary: A Brønsted basicity scale was established for nine representative N-heterocyclic olefins (NHOs) using an UV-visible spectroscopic method. The unsaturated NHOs were found to have stronger basicities compared to their N-heterocyclic carbene (NHC) analogues, while the basicities of the saturated NHOs were weaker. The nucleophilicity of the NHOs was also stronger than commonly used Lewis bases but weaker than their NHC analogues.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Ludwig Zapf, Udo Radius, Maik Finze
Summary: The paper describes the synthesis of 1,3-bis(tricyanoborane)imidazolate anion and its derivatives, including a novel dianionic N-heterocyclic carbene. These compounds exhibit unique electronic and steric properties, making them promising ligands and building blocks for coordination chemistry.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Polymer Science
Hiroaki Shimomoto, Tomohiko Kudo, Shogo Tsunematsu, Tomomichi Itoh, Eiji Ihara
Article
Polymer Science
Tomomichi Itoh, Katsuaki Kojima, Hiroaki Shimomoto, Eiji Ihara
Article
Polymer Science
Hiroaki Shimomoto, Takeshi Mori, Tomomichi Itoh, Eiji Ihara
Article
Polymer Science
Hiroaki Shimomoto, Shohei Ichihara, Hinano Hayashi, Tomomichi Itoh, Eiji Ihara
Article
Polymer Science
Hiroaki Shimomoto, Tomohiro Yamada, Tomomichi Itoh, Eiji Ihara
Article
Chemistry, Multidisciplinary
Hiroaki Shimomoto, Taka-aki Moriya, Takeshi Mori, Tomomichi Itoh, Shinji Kanehashi, Kenji Ogino, Eiji Ihara
Article
Polymer Science
Hiroaki Shimomoto, Ryo Hohsaki, Daisuke Hiramatsu, Tomomichi Itoh, Eiji Ihara
Article
Polymer Science
Hiroaki Shimomoto, Hinano Hayashi, Kyoka Aramasu, Tomomichi Itoh, Eiji Ihara
Summary: Three new N-arylmaleimide-based Pd(0) complexes were synthesized and used as initiators for polymerization of diazoacetates. Experimental observations and mass spectrometry analysis revealed that the initiating species of the polymerization was generated by the insertion of N-arylmaleimide into a Pd-Ph linkage, and this method enables the synthesis of alpha-chain-end-functionalized polymers.
Article
Polymer Science
Tomomichi Itoh, Minami Okuno, Yoshihiro Moriya, Hiroaki Shimomoto, Eiji Ihara
Summary: This study focused on using poly(acrylic acid) block copolymers as stabilizers to modify the surfaces of polymer particles during dispersion polymerization. Polystyrene-block-poly(acrylic acid) was found to have better control over particle size range and surface density compared to poly(acrylic acid) homopolymer. The impact of heterogeneity between the polymer species of the particle core and attached polystyrene or PMMA chains in the poly(acrylic acid) block copolymers was also investigated.
Article
Polymer Science
Hiroaki Shimomoto, Yuto Miyano, Kaito Kinoshita, Tomomichi Itoh, Eiji Ihara
Summary: A series of Pd complexes with diphosphines or diamines and dichloroquinone-derived units as ligands were synthesized and investigated for their initiation abilities in diazoacetate polymerization. It was found that (diphosphine)Pd(ii)Cl(Cl-quinonyl) complexes produced highly syndiotactic polymers, while (diamine)Pd(0)(dichloroquinone) complexes afforded moderately syndiotactic polymers. These findings demonstrate the potential of these complexes as initiating systems for stereoselective diazoacetate polymerization.
Article
Polymer Science
Hiroaki Shimomoto, Itsuki Katashima, Hirokazu Murakami, Tomomichi Itoh, Eiji Ihara
Summary: Diazoacetates with various alkyl groups were polymerized to produce atactic poly(alkoxycarbonylmethylene)s (PACMs) using Pd-based initiating systems, and the effect of alkyl side-chain structure on thermophysical properties was investigated. It was found that using linear and branched side chains with different alkyl chain lengths did not significantly increase the melting point (T (m)) of PACMs. However, incorporating an amide-linkage in the middle of linear alkyl chains effectively raised T (m) due to hydrogen bonding interactions. The spacer length between the ester and amide linkages was crucial for increasing T (m), with the highest T (m) of around 130 degrees C achieved using a C4 spacer length and outer alkyl chain lengths of C7 and C9.
Article
Materials Science, Multidisciplinary
Tomomichi Itoh, Moeka Kimoto, Natsumi Kuroda, Keisuke Ishizaki, Eiji Yukihiro, Hiroaki Shimomoto, Eiji Ihara
Summary: In this study, crosslinked azobenzene polymer particles were developed with light responsiveness, recoverability, and reusability. The particles were successfully prepared with an oblate shape and narrow size distribution using precipitation and dispersion polymerization. The particles exhibited recoverable shape changes upon UV and white light irradiation and were used in light-responsive liquid marbles.
ACS APPLIED POLYMER MATERIALS
(2023)
Article
Polymer Science
Hiroaki Shimomoto, Shogo Tsunematsu, Tomomichi Itoh, Eiji Ihara
Summary: The reactivities of poly(alkoxycarbonylmethylene)s under basic conditions were investigated. Ketene silyl acetal frameworks were formed from reactions with lithium diisopropylamide and trimethylsilyl chloride, and further alkylated through reactions with TBAF and electrophiles. TBAF was found to effectively cleave carbon-carbon bonds in the main chain, leading to well-defined oligomers with higher cleavage frequency compared to vinyl polymer counterparts.
Article
Materials Science, Multidisciplinary
Tomomichi Itoh, Tetsuo Tamamitsu, Tatsuro Aki, Kento Tsutsui, Yuki Mori, Hiroyuki Kudo, Masatoshi Tokita, Hiroaki Shimomoto, Eiji Ihara
ACS APPLIED POLYMER MATERIALS
(2020)
Article
Polymer Science
Hiroaki Shimomoto, Moemi Nakajima, Akihiro Watanabe, Hirokazu Murakami, Tomomichi Itoh, Eiji Ihara
