Tris‐benzo[cd]indole Cyanine Enables the NIR‐photosensitized Radical and Thiol‐ene Polymerizations at 940 nmElian, Christine; Mourot, Benjamin; Benbouziyane, Camil; Malval, Jean‐Pierre; Lajnef, Sonia; Peyrot, Fabienne; Massuyeau, Florian; Siri, Olivier; Jacquemin, Denis; Pascal, Simon; Versace, Davy‐Louis
doi: 10.1002/anie.202305963pmid: 37539471
A near‐infrared‐absorbing heptamethine (HM+) incorporating three bulky benzo[cd]indole heterocycles was designed to efficiently prevent self‐aggregation of the dye, which results in a strong enhancement of its photoinitiating reactivity as compared to a parent bis‐benzo[cd]indole heptamethine (HMCl+) used as a reference system. In this context, we highlight an efficient free‐radical NIR‐polymerization up to a 100 % acrylates C=C bonds conversion even under air conditions. Such an important initiating performance was obtained by incorporating our NIR‐sensitizer into a three‐component system leading to its self‐regeneration. This original photoredox cycle was thoroughly investigated through the identification of each intermediary species using EPR spectroscopy.
Interfacial Self‐assembly of Chiral Selenide Nanomembrane for Enantiospecific RecognitionMeng, Dan; Li, Chen; Hao, Changlong; Shi, Wenxiong; Xu, Jun; Sun, Maozhong; Kuang, Hua; Xu, Chuanlai; Xu, Liguang
doi: 10.1002/anie.202311416pmid: 37677113
Here, we report the synthesis of chiral selenium nanoparticles (NPs) using cysteine and the interfacial assembly strategy to generate a self‐assembled nanomembrane on a large‐scale with controllable morphology and handedness. The selenide (Se) NPs exhibited circular dichroism (CD) bands in the ultraviolet and visible region with a maximum intensity of 39.96 mdeg at 388 nm and optical anisotropy factors (g‐factors) of up to 0.0013 while a self‐assembled monolayer nanomembrane exhibited symmetrical CD approaching 72.8 mdeg at 391 nm and g‐factors up to 0.0034. Analysis showed that a photocurrent of 20.97±1.55 nA was generated by the D‐nanomembrane when irradiated under light while the L‐nanomembrane generated a photocurrent of 20.58±1.36 nA. Owing to the asymmetric intensity of the photocurrent with respect to the handedness of the nanomembrane, an ultrasensitive recognition of enantioselective kynurenine (Kyn) was achieved by the ten‐layer (10L) D‐nanomembrane exhibiting a photocurrent for L‐kynurenine (L‐Kyn) that was 8.64‐fold lower than that of D‐Kyn, with a limit of detection (LOD) of 0.0074 nM for the L‐Kyn, which was attributed to stronger affinity between L‐Kyn and D‐Se NPs. Noticeably, the chiral Se nanomembrane precisely distinguished L‐Kyn in serum and cerebrospinal fluid samples from Alzheimer's disease patients and healthy subjects.
Orthogonal Olefination with OrganogermanesDahiya, Amit; Schoetz, Markus D.; Schoenebeck, Franziska
doi: 10.1002/anie.202310380pmid: 37698171
Reported herein is a fully orthogonal olefination, which involves the site‐ and E‐selective coupling of aryl germanes with alkenes, tolerating otherwise widely employed coupling handles such as aromatic (pseudo)halogens (C−I, C−Br, C−Cl, C−F, C−OTf, C−OSO2F), silanes and boronic acid derivatives as well as alternative functionalities. This unprecedented [Ge]‐based oxidative Heck coupling proceeds at room temperature with high speed (10 min to 2 hours) and operational simplicity owing to its base‐free and air‐tolerant features.
Catalytic Activity of Molybdenum Complexes Bearing PNP‐Type Pincer Ligand toward Ammonia FormationMitsumoto, Taichi; Ashida, Yuya; Arashiba, Kazuya; Kuriyama, Shogo; Egi, Akihito; Tanaka, Hiromasa; Yoshizawa, Kazunari; Nishibayashi, Yoshiaki
doi: 10.1002/anie.202306631pmid: 37382559
We newly designed and prepared a novel molybdenum complex bearing a 4‐[3,5‐bis(trifluoromethyl)phenyl]pyridine‐based PNP‐type pincer ligand, based on the bond dissociation free energies (BDFEs) of the N−H bonds in molybdenum‐imide complexes bearing various substituted pyridine‐based PNP‐type pincer ligands. The complex worked as an excellent catalyst toward ammonia formation from the reaction of an atmospheric pressure of dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions, where up to 3580 equivalents of ammonia were formed based on the molybdenum atom of the catalyst. The catalytic activity was significantly improved by one order of magnitude larger than that observed when using the complex before modification.
An Interfacial View of Cation Effects on Electrocatalysis SystemsKhani, Hadi; Puente Santiago, Alain R.; He, Tianwei
doi: 10.1002/anie.202306103pmid: 37490318
The identity of alkali metal cations in the electrolyte of electrocatalysis systems has been recently introduced as a crucial factor to tailor the kinetics and Faradaic efficiency of many electrocatalytic reactions. In this Minireview, we have summarized the recent advances in the molecular‐level understanding of cation effects on relevant electrocatalytic processes such as hydrogen evolution (HER), oxygen evolution (OER), and CO2 electroreduction (CO2RR) reactions. The discussion covers the effects of electrolyte cations on interfacial electric fields, structural organization of interfacial water molecules, blocking the catalytic active sites, stabilization or destabilization of intermediates, and interfacial pHs. These cation‐induced interfacial phenomena have been reported to impact the performance (activity, selectivity, and stability) of electrochemical reactions collaboratively or independently. We describe that although there is almost a general agreement on the relationship between the size of alkali cations and the activities of HER, OER, and CO2RR, however, the mechanism by which the performance of these electrocatalytic reactions is influenced by alkali metal cations is still in debate.
Promoter‐Controlled Synthesis and Conformational Analysis of Cyclic Mannosides up to a 32‐merLi, Xiaona; Di Carluccio, Cristina; Miao, He; Zhang, Lvfeng; Shang, Jintao; Molinaro, Antonio; Xu, Peng; Silipo, Alba; Yu, Biao; Yang, You
doi: 10.1002/anie.202307851pmid: 37433753
Cyclodextrins are widely used as carriers of small molecules for drug delivery owing to their remarkable host properties and excellent biocompatibility. However, cyclic oligosaccharides with different sizes and shapes are limited. Cycloglycosylation of ultra‐large bifunctional saccharide precursors is challenging due to the constrained conformational spaces. Herein we report a promoter‐controlled cycloglycosylation approach for the synthesis of cyclic α‐(1→6)‐linked mannosides up to a 32‐mer. Cycloglycosylation of the bifunctional thioglycosides and (Z)‐ynenoates was found to be highly dependent on the promoters. In particular, a sufficient amount of a gold(I) complex played a key role in the proper preorganization of the ultra‐large cyclic transition state, providing a cyclic 32‐mer polymannoside, which represents the largest synthetic cyclic polysaccharide to date. NMR experiments and a computational study revealed that the cyclic 2‐mer, 4‐mer, 8‐mer, 16‐mer, and 32‐mer mannosides adopted different conformational states and shapes.
Motorized Photomodulator: Making A Non‐photoresponsive Supramolecular Gel Switchable by LightShan, Yahan; Zhang, Qi; Sheng, Jinyu; Stuart, Marc C. A.; Qu, Da‐Hui; Feringa, Ben L.
doi: 10.1002/anie.202310582pmid: 37681477
Introducing photo‐responsive molecules offers an attractive approach for remote and selective control and dynamic manipulation of material properties. However, it remains highly challenging how to use a minimal amount of photo‐responsive units to optically modulate materials that are inherently inert to light irradiation. Here we show the application of a light‐driven rotary molecular motor as a “motorized photo‐modulator” to endow a typical H‐bond‐based gel system with the ability to respond to light irradiation and create a reversible sol‐gel transition. The key molecular design feature is the introduction of a minimal amount (2 mol %) of molecular motors into the supramolecular network as photo‐switchable non‐covalent crosslinkers. Advantage is taken of the subtle interplay of the large geometry change during photo‐isomerization of the molecular motor guest and the dynamic nature of a supramolecular gel host system. As a result, a tiny amount of molecular motors is enough to switch the mechanical modulus of the entire supramolecular systems. This study proves the concept of designing photo‐responsive materials with minimum use of non‐covalent light‐absorbing units.