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As a model of a chemical upcycling process, we have developed a single-metal homogeneous catalytic system to break down persistent polyethylene waste into valuable chemical intermediates. This could ultimately be used to produce important chemical products, including environmentally friendly, biodegradable plastics. In the first step, a slow pyrolysis of polyolefin waste yields oils, containing long-chain olefins as the major components. Then, for the next transformation step, tailored bicyclic (alkyl)(amino)carbene (BICAAC)-Ru olefin metathesis catalysts were used in combination with an alkene isomerization catalyst (RuHCl(CO)(PPh3)3) for the transformation of the pyrolysis oil to propylene via isomerization-metathesis (ISOMET) reaction in ethylene atmosphere. Eventually, translation of the highly efficient single-metal catalyst system enabled ISOMET reaction to a 900 mL reactor setup and repetitive batch experiments could prove the long-term stability of the catalyst system and the highest total turnover number (tTON = 2788 mol propylene per mol olefin metathesis catalyst) reported so far using post-consumer polyethylene waste feedstock. [ABSTRACT FROM AUTHOR]

An effective, GFP‐inspired fluorescent Zn2+ sensor is developed for two–photon microscopy and related biological application that features an 8‐methoxyquinoline moiety. Excellent photophysical characteristics including a 37‐fold fluorescence enhancement with excitation and emission maxima at 440 nm and 505 nm, respectively, as well as a high two–photon cross–section of 73 GM at 880 nm are reported. Based on the experimental data, the relationship between the structure and properties was elucidated and explained backed up by DFT calculations, particularly the observed PeT phenomenon for the turn–on process. Biological validation and detailed experimental and theoretical characterization of the free and the zinc–bound compounds are presented. [ABSTRACT FROM AUTHOR]

The few commercially available chemosensors and published probes for in vitro Zn2+ detection in two-photon microscopy are compromised by their flawed spectroscopic properties, causing issues in selectivity or challenging multistep syntheses. Herein, we present the development of an effective small molecular GFP chromophore-based fluorescent chemosensor with a 2,2′-bipyridine chelator moiety (GFZnP BIPY) for Zn2+ detection that has straightforward synthesis and uncompromised properties. Detailed experimental characterizations of the free and the zinc-bound compounds within the physiologically relevant pH range are presented. Excellent photophysical characteristics are reported, including a 53-fold fluorescence enhancement with excitation and emission maxima at 422 nm and 492 nm, respectively. A high two-photon cross section of 3.0 GM at 840 nm as well as excellent metal ion selectivity are reported. In vitro experiments on HEK 293 cell culture were carried out using two-photon microscopy to demonstrate the applicability of the novel sensor for zinc bioimaging. [ABSTRACT FROM AUTHOR]

An alternative solution to the problem of plastic waste is the development of chemical processes that enable the synthesis of sustainable materials from persistent plastics. The catalytic decomposition of post‐consumer HDPE waste by isomerization metathesis (ISOMET) enables the production of propylene, the precursor of allyl acetate. In their Research Article (DOI: 10.1002/chem.202401918), M. Nagyházi, R. Tuba and co‐workers recount their development of new ruthenium catalysts that can carry out consecutive olefin metathesis and hydrogenation reactions of allyl acetate to butane‐1,4‐diol, the precursor of biodegradable and chemically recyclable materials, including polybutylene succinate (PBS). [ABSTRACT FROM AUTHOR]

Since the first discovery by Huigsen and co‐workers fifty years ago, a wide range of organic reactions have taken place through the intermediary of the dipolar/zwitterionic species produced by the combination of a neutral nucleophile and an unsaturated electrophile. Nucleophilic initiators including heterocycles may react or play a mediating role based on their nucleophilic nature and reaction conditions. This review highlights the recent developments of the cyclization chemistry of heterocycles using multicomponent reactions (MCRs) – including unusual dearomatizative examples. Heterocycles as very common structural units can often be found in natural and pharmaceutical products. MCRs are environmentally benign and highly atom economic reactions. Their application in the synthesis of biologically active molecules may provide alternatives for the greener synthesis of drugs lowering the carbon footprint of pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Non-metallic η²-H2 complexes are extremely rare; moreover in the case of boranes (with the exception of the BH5 molecule) the existence of such structures was only indicated by computational studies. In a recent paper we have demonstrated that external electron donor groups can stabilize the η²-H2 complexes, similar to the backdonation in the case of transition metals. In this paper we present evidence of a new stabilizing effect: electron donation from the B-R bonds to the H2 σ* orbital. The stability and electronic structure of several mono-, di-, and trisubstituted borane-H2 complexes were investigated by ab initio calculations. SiR3 groups were found to facilitate the σ(B-R)σ*(H-H) interaction, increasing the stability of the η² complexes. Furthermore in the case of tris(trimethyl)silylborane, the exceptional stability of a novel neutral pentavalent borane structure is shown. [ABSTRACT FROM AUTHOR]

A series of a novel CAAC ligands featuring a spiro-fluorene group have been synthesized and complexed with ruthenium alkylidenes, yielding the corresponding Hoveyda-type derivatives as a new family of olefin metathesis catalysts. The novel complexes have been characterized by XRD, HRMS and NMR measurements. The synthetised complexes were tested in catalysis and showed good activity in olefin metathesis, as demonstrated on diethyl diallylmalonate and allyl acetate substrates. The unique backbone in the ligand with the large, yet inflexible condensed system renders interesting properties to the catalyst, exemplified by the good catalytic performance and improved Z-selectivity. In addition, the complex can also serve as a hydrogenation catalyst in a consecutive (one-pot) reaction. The latter reaction can convert allyl acetate to butane-1,4-diol, a valuable chemical intermediate for biodegradable polybutylene succinate (PBS)., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

An effective, GFP-inspired fluorescent Zn 2+ sensor is developed for two-photon microscopy and related biological application that features an 8-methoxyquinoline moiety. Excellent photophysical characteristics including a 37-fold fluorescence enhancement with excitation and emission maxima at 440 nm and 505 nm, respectively, as well as a high two-photon cross-section of 73 GM at 880 nm are reported. Based on the experimental data, the relationship between the structure and properties was elucidated and explained backed up by DFT calculations, particularly the observed PeT phenomenon for the turn-on process. Biological validation and detailed experimental and theoretical characterization of the free and the zinc-bound compounds are presented., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Non-metallic η(2)-H2 complexes are extremely rare; moreover in the case of boranes (with the exception of the BH5 molecule) the existence of such structures was only indicated by computational studies. In a recent paper we have demonstrated that external electron donor groups can stabilize the η(2)-H2 complexes, similar to the backdonation in the case of transition metals. In this paper we present evidence of a new stabilizing effect: electron donation from the B-R bonds to the H2 σ* orbital. The stability and electronic structure of several mono-, di-, and trisubstituted borane-H2 complexes were investigated by ab initio calculations. SiR3 groups were found to facilitate the σ(B-R)→σ*(H-H) interaction, increasing the stability of the η(2) complexes. Furthermore in the case of tris(trimethyl)silylborane, the exceptional stability of a novel neutral pentavalent borane structure is shown.