Pub Date : 2024-06-05DOI: 10.1021/acsorginorgau.4c0003210.1021/acsorginorgau.4c00032
Badaraita Gorachand, Gundam Surendra Reddy and Dhevalapally B. Ramachary*,
Carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles are well-known for their wide range of applications in pharmaceutical and medicinal chemistry, but their high-yielding metal-free synthesis has always remained challenging, as no comprehensive protocol has been outlined to date. Owing to their structural and medicinal importance, herein, we synthesized various carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles and unsymmetrical 4,5′-bitriazoles with high yields and chemo-/regioselectivity from the library of 2,4-diketoesters and azides in a sequential one-pot manner through the combination of organocatalytic enolization, in situ [3 + 2]-cycloaddition, and hydrolysis reactions. The commercial availability of the starting materials/catalysts, diverse substrate scope, performance in a one-pot manner, chemo-/regioselectivity of organo-click reaction, quick synthesis of unsymmetrical 4,5′-bitriazoles, a large number of synthetic applications, and numerous medicinal applications of carbonyl-containing 1,2,3-triazoles are the key attractions of this metal-free organo-click work.
{"title":"Direct Organocatalytic Chemoselective Synthesis of Pharmaceutically Active 1,2,3-Triazoles and 4,5′-Bitriazoles","authors":"Badaraita Gorachand, Gundam Surendra Reddy and Dhevalapally B. Ramachary*, ","doi":"10.1021/acsorginorgau.4c0003210.1021/acsorginorgau.4c00032","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00032https://doi.org/10.1021/acsorginorgau.4c00032","url":null,"abstract":"<p >Carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles are well-known for their wide range of applications in pharmaceutical and medicinal chemistry, but their high-yielding metal-free synthesis has always remained challenging, as no comprehensive protocol has been outlined to date. Owing to their structural and medicinal importance, herein, we synthesized various carbonyl-containing 1,4,5-trisubstituted- and 1,4-disubstituted-1,2,3-triazoles and unsymmetrical 4,5′-bitriazoles with high yields and chemo-/regioselectivity from the library of 2,4-diketoesters and azides in a sequential one-pot manner through the combination of organocatalytic enolization, in situ [3 + 2]-cycloaddition, and hydrolysis reactions. The commercial availability of the starting materials/catalysts, diverse substrate scope, performance in a one-pot manner, chemo-/regioselectivity of organo-click reaction, quick synthesis of unsymmetrical 4,5′-bitriazoles, a large number of synthetic applications, and numerous medicinal applications of carbonyl-containing 1,2,3-triazoles are the key attractions of this metal-free organo-click work.</p>","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsorginorgau.4c00032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142402780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.1021/acsorginorgau.4c0003010.1021/acsorginorgau.4c00030
Jordi C. J. Hintzen, Shitanshu Devrani, Andrew J. Carrod, M. Bahadir Bayik, Daniel Tietze and Alesia A. Tietze*,
Labeling of peptides and proteins with fluorescent dyes is a key step in functionalizing these structures for a wide array of biological assays. However, coupling strategies of such dyes have not been optimized for the most common compounds, while this step is typically the most precious and costly of the whole synthesis. We searched for the best conditions for attachment of the most widely used fluorescent dyes such as 6-carboxyfluorescein, Rhodamine B, and BODIPY-FL to peptides, where amino terminal Cu(II) and Ni(II) binding site (ATCUN) peptides were used as a model system. Surprisingly, conventional methods of dye attachment proved to not be satisfactory and yielded poor efficiency results. We have discovered that when labeling primary amines on peptides, the uncommon synthesis of activated pentafluorophenol (PFP) esters is the most efficient strategy, expedited by microwave irradiation. Coupling to secondary amines is achieved most efficiently through conventional coupling reagents such as HATU and PyBOP. Furthermore, we have employed our fluorescently labeled ATCUN peptides in studies for Cu(II) and Ni(II) sensing, showing that changing the fluorophore does not significantly affect the fluorescence quenching process and discovering the optimal linker length between the ATCUN core and the dye, expanding the repertoire of fluorophores that can be used in this application.
{"title":"Fluorescence Labeling of Peptides: Finding the Optimal Protocol for Coupling Various Dyes to ATCUN-like Structures","authors":"Jordi C. J. Hintzen, Shitanshu Devrani, Andrew J. Carrod, M. Bahadir Bayik, Daniel Tietze and Alesia A. Tietze*, ","doi":"10.1021/acsorginorgau.4c0003010.1021/acsorginorgau.4c00030","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00030https://doi.org/10.1021/acsorginorgau.4c00030","url":null,"abstract":"<p >Labeling of peptides and proteins with fluorescent dyes is a key step in functionalizing these structures for a wide array of biological assays. However, coupling strategies of such dyes have not been optimized for the most common compounds, while this step is typically the most precious and costly of the whole synthesis. We searched for the best conditions for attachment of the most widely used fluorescent dyes such as 6-carboxyfluorescein, Rhodamine B, and BODIPY-FL to peptides, where amino terminal Cu(II) and Ni(II) binding site (ATCUN) peptides were used as a model system. Surprisingly, conventional methods of dye attachment proved to not be satisfactory and yielded poor efficiency results. We have discovered that when labeling primary amines on peptides, the uncommon synthesis of activated pentafluorophenol (PFP) esters is the most efficient strategy, expedited by microwave irradiation. Coupling to secondary amines is achieved most efficiently through conventional coupling reagents such as HATU and PyBOP. Furthermore, we have employed our fluorescently labeled ATCUN peptides in studies for Cu(II) and Ni(II) sensing, showing that changing the fluorophore does not significantly affect the fluorescence quenching process and discovering the optimal linker length between the ATCUN core and the dye, expanding the repertoire of fluorophores that can be used in this application.</p>","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsorginorgau.4c00030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142402779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-16DOI: 10.1021/acsorginorgau.4c0001310.1021/acsorginorgau.4c00013
Ryuki Sumida, Lorenzo Catti and Michito Yoshizawa*,
Linear monoterpenes, versatile reaction biosubstrates, are bound and subsequently converted to various cyclic monomers and oligomers with excellent selectivity and efficiency, only in natural enzymes. We herein report bioinspired functions of synthetic polyaromatic cavities toward linear monoterpenes in the solution and solid states. The cavities are provided by polyaromatic coordination capsules, formed by the assembly of Pt(II) ions and bent bispyridine ligands with two anthracene panels. By using the capsule cavities, the selective binding of citronellal from mixtures with other monoterpenes and its preferential vapor binding over its derivatives are demonstrated in water and in the solid state, respectively. The capsule furthermore extracts p-menthane-3,8-diol, with high product- and stereoselectivity, from a reaction mixture obtained by the acid-catalyzed cyclization of citronellal in water. Thanks to the inner and outer polyaromatic cavities, the catalytic cyclization-dimerization of vaporized citronellal efficiently proceeds in the acid-loaded capsule solid and product/stereoselectively affords p-menthane-3,8-diol citronellal acetal (∼330% yield based on the capsule) under ambient conditions. The solid capsule reactor can be reused at least 5 times with enhanced conversion. The present study opens up a new approach toward mimicking terpene biosynthesis via synthetic polyaromatic cavities.
{"title":"Bioinspired Binding and Conversion of Linear Monoterpenes by Polyaromatic Coordination Capsules","authors":"Ryuki Sumida, Lorenzo Catti and Michito Yoshizawa*, ","doi":"10.1021/acsorginorgau.4c0001310.1021/acsorginorgau.4c00013","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00013https://doi.org/10.1021/acsorginorgau.4c00013","url":null,"abstract":"<p >Linear monoterpenes, versatile reaction biosubstrates, are bound and subsequently converted to various cyclic monomers and oligomers with excellent selectivity and efficiency, <i>only</i> in natural enzymes. We herein report bioinspired functions of synthetic polyaromatic cavities toward linear monoterpenes in the solution and solid states. The cavities are provided by polyaromatic coordination capsules, formed by the assembly of Pt(II) ions and bent bispyridine ligands with two anthracene panels. By using the capsule cavities, the selective binding of citronellal from mixtures with other monoterpenes and its preferential vapor binding over its derivatives are demonstrated in water and in the solid state, respectively. The capsule furthermore extracts <i>p</i>-menthane-3,8-diol, with high product- and stereoselectivity, from a reaction mixture obtained by the acid-catalyzed cyclization of citronellal in water. Thanks to the inner and outer polyaromatic cavities, the catalytic cyclization-dimerization of vaporized citronellal efficiently proceeds in the acid-loaded capsule solid and product/stereoselectively affords <i>p</i>-menthane-3,8-diol citronellal acetal (∼330% yield based on the capsule) under ambient conditions. The solid capsule reactor can be reused at least 5 times with enhanced conversion. The present study opens up a new approach toward mimicking terpene biosynthesis via synthetic polyaromatic cavities.</p>","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsorginorgau.4c00013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141959334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.1021/acsorginorgau.4c0002810.1021/acsorginorgau.4c00028
Serhii Holovach, Illia Poroshyn, Kostiantyn P. Melnykov, Oleksandr S. Liashuk, Olena O. Pariiska, Sergey V. Kolotilov, Alexander B. Rozhenko, Dmytro M. Volochnyuk and Oleksandr O. Grygorenko*,
Parallel Minisci reactions of nonfluorinated and gem-difluorinated C4–C7 cycloalkyl building blocks (trifluoroborates and carboxylic acids) with a series of electron-deficient heterocycles were studied. A comparison of the reaction’s outcome revealed better product yields in the case of carboxylic acids as the radical precursors in most cases, albeit these reagents were used with three-fold excess under optimized conditions. The nature of the heterocyclic core was found to be important for successful incorporation of the cycloalkyl fragment. The impact of the CF2 moiety on the oxidation potential of fluorinated cycloalkyl trifluoroborates and the reaction outcome, in general, was also evaluated.
{"title":"Parallel Minisci Reaction of gem-Difluorocycloalkyl Building Blocks","authors":"Serhii Holovach, Illia Poroshyn, Kostiantyn P. Melnykov, Oleksandr S. Liashuk, Olena O. Pariiska, Sergey V. Kolotilov, Alexander B. Rozhenko, Dmytro M. Volochnyuk and Oleksandr O. Grygorenko*, ","doi":"10.1021/acsorginorgau.4c0002810.1021/acsorginorgau.4c00028","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00028https://doi.org/10.1021/acsorginorgau.4c00028","url":null,"abstract":"<p >Parallel Minisci reactions of nonfluorinated and <i>gem</i>-difluorinated C<sub>4</sub>–C<sub>7</sub> cycloalkyl building blocks (trifluoroborates and carboxylic acids) with a series of electron-deficient heterocycles were studied. A comparison of the reaction’s outcome revealed better product yields in the case of carboxylic acids as the radical precursors in most cases, albeit these reagents were used with three-fold excess under optimized conditions. The nature of the heterocyclic core was found to be important for successful incorporation of the cycloalkyl fragment. The impact of the CF<sub>2</sub> moiety on the oxidation potential of fluorinated cycloalkyl trifluoroborates and the reaction outcome, in general, was also evaluated.</p>","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsorginorgau.4c00028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141959333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1021/acsorginorgau.4c0000910.1021/acsorginorgau.4c00009
Steffan K. Kristensen, Alexander Ahrens, Bjarke S. Donslund and Troels Skrydstrup,
In order to prevent the current unsustainable waste handling of the enormous volumes of end-of-use organic polymer material sent to landfilling or incineration, extensive research efforts have been devoted toward the development of appropriate solutions for the recycling of commercial thermoset polymers. The inability of such cross-linked polymers to be remelted once cured implies that mechanical recycling processes used for thermoplastic materials do not translate to the recycling of thermoset polymers. Moreover, the structural diversity within the materials from the use of different monomers as well as the use of such polymers for the fabrication of fiber-reinforced polymer composites make recycling of these materials highly challenging. In this Perspective, depolymerization strategies for thermoset polymers are discussed with an emphasis on recent advancements within our group on recovering polymer building blocks from polyurethane (PU) and epoxy-based materials. While these two represent the largest thermoset polymer groups with respect to the production volumes, the recycling landscapes for these classes of materials are vastly different. For PU, increased collaboration between academia and industry has resulted in major advancements within solvolysis, acidolysis, aminolysis, and split-phase glycolysis for polyol recovery, where several processes are being evaluated for further scaling studies. For epoxy-based materials, the molecular skeleton has no obvious target for chemical scission. Nevertheless, we have recently demonstrated the possibility of the disassembly of the epoxy polymer in fiber-reinforced composites for bisphenol A (BPA) recovery through catalytic C–O bond cleavage. Furthermore, a base promoted cleavage developed by us and others shows tremendous potential for the recovery of BPA from epoxy polymers. Further efforts are still required for evaluating the suitability of such monomer recovery strategies for epoxy materials at an industrial scale. Nonetheless, recent advancements as illustrated with the presented chemistry suggest that the future of thermoset polymer recycling could include processes that emphasize monomer recovery in an energy efficient manner for closed-loop recycling.
目前,大量的有机聚合物材料在使用结束后被送往垃圾填埋场或焚化炉焚烧,为了防止这种不可持续的废物处理方式,人们已经投入了大量的研究工作,为商用热固性聚合物的回收利用开发适当的解决方案。这种交联聚合物在固化后无法重新熔化,这意味着用于热塑性材料的机械回收工艺无法转化为热固性聚合物的回收工艺。此外,由于使用了不同的单体,这些材料的结构也各不相同,而且这些聚合物还可用于制造纤维增强聚合物复合材料,因此这些材料的回收利用工作极具挑战性。本视角将讨论热固性聚合物的解聚策略,重点介绍我们小组最近在从聚氨酯(PU)和环氧基材料中回收聚合物结构单元方面取得的进展。虽然就产量而言,这两种材料是最大的热固性聚合物,但这两类材料的回收情况却大相径庭。就聚氨酯而言,学术界和工业界加强合作,在多元醇回收的溶解、酸解、氨解和分相乙二醇分解方面取得了重大进展,目前正在对几种工艺进行评估,以进一步扩大研究范围。对于环氧基材料,分子骨架没有明显的化学裂解目标。不过,我们最近已经证明,通过催化 C-O 键裂解,可以分解纤维增强复合材料中的环氧聚合物,从而回收双酚 A(BPA)。此外,我们和其他人开发的碱促进裂解技术也显示出从环氧聚合物中回收双酚 A 的巨大潜力。要评估此类单体回收策略在工业规模的环氧材料中的适用性,仍需进一步努力。尽管如此,本文介绍的化学方法所展示的最新进展表明,热固性聚合物回收的未来可能包括以高效节能的方式进行单体回收以实现闭环回收的工艺。
{"title":"Perspective on the Development of Monomer Recovery Technologies from Plastics Designed to Last","authors":"Steffan K. Kristensen, Alexander Ahrens, Bjarke S. Donslund and Troels Skrydstrup, ","doi":"10.1021/acsorginorgau.4c0000910.1021/acsorginorgau.4c00009","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00009https://doi.org/10.1021/acsorginorgau.4c00009","url":null,"abstract":"<p >In order to prevent the current unsustainable waste handling of the enormous volumes of end-of-use organic polymer material sent to landfilling or incineration, extensive research efforts have been devoted toward the development of appropriate solutions for the recycling of commercial thermoset polymers. The inability of such cross-linked polymers to be remelted once cured implies that mechanical recycling processes used for thermoplastic materials do not translate to the recycling of thermoset polymers. Moreover, the structural diversity within the materials from the use of different monomers as well as the use of such polymers for the fabrication of fiber-reinforced polymer composites make recycling of these materials highly challenging. In this Perspective, depolymerization strategies for thermoset polymers are discussed with an emphasis on recent advancements within our group on recovering polymer building blocks from polyurethane (PU) and epoxy-based materials. While these two represent the largest thermoset polymer groups with respect to the production volumes, the recycling landscapes for these classes of materials are vastly different. For PU, increased collaboration between academia and industry has resulted in major advancements within solvolysis, acidolysis, aminolysis, and split-phase glycolysis for polyol recovery, where several processes are being evaluated for further scaling studies. For epoxy-based materials, the molecular skeleton has no obvious target for chemical scission. Nevertheless, we have recently demonstrated the possibility of the disassembly of the epoxy polymer in fiber-reinforced composites for bisphenol A (BPA) recovery through catalytic C–O bond cleavage. Furthermore, a base promoted cleavage developed by us and others shows tremendous potential for the recovery of BPA from epoxy polymers. Further efforts are still required for evaluating the suitability of such monomer recovery strategies for epoxy materials at an industrial scale. Nonetheless, recent advancements as illustrated with the presented chemistry suggest that the future of thermoset polymer recycling could include processes that emphasize monomer recovery in an energy efficient manner for closed-loop recycling.</p>","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsorginorgau.4c00009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141957246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1021/acsorginorgau.4c00009
Steffan K. Kristensen, Alexander Ahrens, Bjarke S. Donslund, Troels Skrydstrup
In order to prevent the current unsustainable waste handling of the enormous volumes of end-of-use organic polymer material sent to landfilling or incineration, extensive research efforts have been devoted toward the development of appropriate solutions for the recycling of commercial thermoset polymers. The inability of such cross-linked polymers to be remelted once cured implies that mechanical recycling processes used for thermoplastic materials do not translate to the recycling of thermoset polymers. Moreover, the structural diversity within the materials from the use of different monomers as well as the use of such polymers for the fabrication of fiber-reinforced polymer composites make recycling of these materials highly challenging. In this Perspective, depolymerization strategies for thermoset polymers are discussed with an emphasis on recent advancements within our group on recovering polymer building blocks from polyurethane (PU) and epoxy-based materials. While these two represent the largest thermoset polymer groups with respect to the production volumes, the recycling landscapes for these classes of materials are vastly different. For PU, increased collaboration between academia and industry has resulted in major advancements within solvolysis, acidolysis, aminolysis, and split-phase glycolysis for polyol recovery, where several processes are being evaluated for further scaling studies. For epoxy-based materials, the molecular skeleton has no obvious target for chemical scission. Nevertheless, we have recently demonstrated the possibility of the disassembly of the epoxy polymer in fiber-reinforced composites for bisphenol A (BPA) recovery through catalytic C–O bond cleavage. Furthermore, a base promoted cleavage developed by us and others shows tremendous potential for the recovery of BPA from epoxy polymers. Further efforts are still required for evaluating the suitability of such monomer recovery strategies for epoxy materials at an industrial scale. Nonetheless, recent advancements as illustrated with the presented chemistry suggest that the future of thermoset polymer recycling could include processes that emphasize monomer recovery in an energy efficient manner for closed-loop recycling.
目前,大量的有机聚合物材料在使用结束后被送往垃圾填埋场或焚化炉焚烧,为了防止这种不可持续的废物处理方式,人们已经投入了大量的研究工作,为商用热固性聚合物的回收利用开发适当的解决方案。这种交联聚合物在固化后无法重新熔化,这意味着用于热塑性材料的机械回收工艺无法转化为热固性聚合物的回收工艺。此外,由于使用了不同的单体,这些材料的结构也各不相同,而且这些聚合物还可用于制造纤维增强聚合物复合材料,因此这些材料的回收利用工作极具挑战性。本视角将讨论热固性聚合物的解聚策略,重点介绍我们小组最近在从聚氨酯(PU)和环氧基材料中回收聚合物结构单元方面取得的进展。虽然就产量而言,这两种材料是最大的热固性聚合物,但这两类材料的回收情况却大相径庭。就聚氨酯而言,学术界和工业界加强合作,在多元醇回收的溶解、酸解、氨解和分相乙二醇分解方面取得了重大进展,目前正在对几种工艺进行评估,以进一步扩大研究范围。对于环氧基材料,分子骨架没有明显的化学裂解目标。不过,我们最近已经证明,通过催化 C-O 键裂解,可以分解纤维增强复合材料中的环氧聚合物,从而回收双酚 A(BPA)。此外,我们和其他人开发的碱促进裂解技术也显示出从环氧聚合物中回收双酚 A 的巨大潜力。要评估此类单体回收策略在工业规模的环氧材料中的适用性,仍需进一步努力。尽管如此,本文介绍的化学方法所展示的最新进展表明,热固性聚合物回收的未来可能包括以高效节能的方式进行单体回收以实现闭环回收的工艺。
{"title":"Perspective on the Development of Monomer Recovery Technologies from Plastics Designed to Last","authors":"Steffan K. Kristensen, Alexander Ahrens, Bjarke S. Donslund, Troels Skrydstrup","doi":"10.1021/acsorginorgau.4c00009","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00009","url":null,"abstract":"In order to prevent the current unsustainable waste handling of the enormous volumes of end-of-use organic polymer material sent to landfilling or incineration, extensive research efforts have been devoted toward the development of appropriate solutions for the recycling of commercial thermoset polymers. The inability of such cross-linked polymers to be remelted once cured implies that mechanical recycling processes used for thermoplastic materials do not translate to the recycling of thermoset polymers. Moreover, the structural diversity within the materials from the use of different monomers as well as the use of such polymers for the fabrication of fiber-reinforced polymer composites make recycling of these materials highly challenging. In this Perspective, depolymerization strategies for thermoset polymers are discussed with an emphasis on recent advancements within our group on recovering polymer building blocks from polyurethane (PU) and epoxy-based materials. While these two represent the largest thermoset polymer groups with respect to the production volumes, the recycling landscapes for these classes of materials are vastly different. For PU, increased collaboration between academia and industry has resulted in major advancements within solvolysis, acidolysis, aminolysis, and split-phase glycolysis for polyol recovery, where several processes are being evaluated for further scaling studies. For epoxy-based materials, the molecular skeleton has no obvious target for chemical scission. Nevertheless, we have recently demonstrated the possibility of the disassembly of the epoxy polymer in fiber-reinforced composites for bisphenol A (BPA) recovery through catalytic C–O bond cleavage. Furthermore, a base promoted cleavage developed by us and others shows tremendous potential for the recovery of BPA from epoxy polymers. Further efforts are still required for evaluating the suitability of such monomer recovery strategies for epoxy materials at an industrial scale. Nonetheless, recent advancements as illustrated with the presented chemistry suggest that the future of thermoset polymer recycling could include processes that emphasize monomer recovery in an energy efficient manner for closed-loop recycling.","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-19DOI: 10.1021/acsorginorgau.3c0007010.1021/acsorginorgau.3c00070
Larissa A. Casper, Katharina L. Deuter, Anja Rehse and Rainer F. Winter*,
We report on three new 9-phenyl-substituted ferroceno[2,3]indenylmethylium dyes 1+–3+ with electron-donating (OMe, Me) or electron-withdrawing (CF3) substituents. Complexes 1+–3+ exist as racemic mixtures of Rp and Sp enantiomers. Pyramidalization at the methyl C atom in the precursor carbinol species 1-OH–3-OH or the corresponding one-electron reduced radicals induces a second stereocenter, as the 9-phenyl substituent may reside in an endo or an exo position. Indeed, alcohol 2-OH crystallizes as a racemate of Rp,S and Sp,R isomers. Cationic complexes 1+–3+ are of deep green color and show intense electronic absorption in the visible. The oxidation and reduction processes are thoroughly investigated by means of cyclic voltammetry and UV/vis/NIR spectroelectrochemistry, the latter showing their electrochromic behavior. T-dependent EPR spectroscopy, EPR spin counting at 20 °C, as well as the UV/vis/NIR spectra of the reduced samples suggest that the one-electron reduced, neutral radicals dimerize nearly quantitatively (≥99.98%). Chemical reduction of 2+ furnished an isomeric mixture of dimeric 2–2. As was shown by cyclic voltammetry and UV/vis/NIR spectroelectrochemistry, the latter dimer redissociates to monomers 2+ upon oxidation, thereby closing a reversible cycle of redox-induced C–C bond making and breaking.
我们报告了三种新的 9-苯基取代二茂铁[2,3]茚基甲基染料 1+-3+,它们带有电子捐赠(OMe、Me)或电子撤回(CF3)取代基。络合物 1+-3+ 是 Rp 和 Sp 对映体的外消旋混合物。前体 1-OH-3-OH 或相应的单电子还原基中甲基 C 原子的金字塔化会产生第二个立体中心,因为 9-苯基取代基可能位于内位或外位。事实上,2-OH 醇结晶为 Rp,S 和 Sp,R 异构体的外消旋体。阳离子络合物 1+-3+ 呈深绿色,在可见光下有强烈的电子吸收。通过循环伏安法和紫外/可见/近红外光谱电化学法对氧化和还原过程进行了深入研究,后者显示了它们的电致变色行为。依赖于 T 的 EPR 光谱、20 °C 时的 EPR 自旋计数以及还原样品的紫外/可见光/近红外光谱表明,单电子还原的中性自由基几乎定量二聚(≥99.98%)。2+ 的化学还原产生了二聚体 2-2 的异构混合物。正如循环伏安法和紫外/可见光/近红外光谱电化学法所示,后一种二聚体在氧化时重新解离成单体 2+,从而结束了氧化还原引起的 C-C 键生成和断裂的可逆循环。
{"title":"Dimerization of 9-Phenyl-ferroceno[2,3]indenylmethyl Radicals: Electrochemical and Spectroelectrochemical Studies","authors":"Larissa A. Casper, Katharina L. Deuter, Anja Rehse and Rainer F. Winter*, ","doi":"10.1021/acsorginorgau.3c0007010.1021/acsorginorgau.3c00070","DOIUrl":"https://doi.org/10.1021/acsorginorgau.3c00070https://doi.org/10.1021/acsorginorgau.3c00070","url":null,"abstract":"<p >We report on three new 9-phenyl-substituted ferroceno[2,3]indenylmethylium dyes <b>1</b><sup><b>+</b></sup>–<b>3</b><sup><b>+</b></sup> with electron-donating (OMe, Me) or electron-withdrawing (CF<sub>3</sub>) substituents. Complexes <b>1</b><sup><b>+</b></sup>–<b>3</b><sup><b>+</b></sup> exist as racemic mixtures of <i>Rp</i> and <i>Sp</i> enantiomers. Pyramidalization at the methyl C atom in the precursor carbinol species <b>1-OH</b>–<b>3-OH</b> or the corresponding one-electron reduced radicals induces a second stereocenter, as the 9-phenyl substituent may reside in an <i>endo</i> or an <i>exo</i> position. Indeed, alcohol <b>2-OH</b> crystallizes as a racemate of <i>Rp</i>,<i>S</i> and <i>Sp</i>,<i>R</i> isomers. Cationic complexes <b>1</b><sup><b>+</b></sup>–<b>3</b><sup><b>+</b></sup> are of deep green color and show intense electronic absorption in the visible. The oxidation and reduction processes are thoroughly investigated by means of cyclic voltammetry and UV/vis/NIR spectroelectrochemistry, the latter showing their electrochromic behavior. <i>T</i>-dependent EPR spectroscopy, EPR spin counting at 20 °C, as well as the UV/vis/NIR spectra of the reduced samples suggest that the one-electron reduced, neutral radicals dimerize nearly quantitatively (≥99.98%). Chemical reduction of <b>2</b><sup><b>+</b></sup> furnished an isomeric mixture of dimeric <b>2</b>–<b>2</b>. As was shown by cyclic voltammetry and UV/vis/NIR spectroelectrochemistry, the latter dimer redissociates to monomers <b>2</b><sup><b>+</b></sup> upon oxidation, thereby closing a reversible cycle of redox-induced C–C bond making and breaking.</p>","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsorginorgau.3c00070","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141954741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-26DOI: 10.1021/acsorginorgau.4c0000510.1021/acsorginorgau.4c00005
Peter J. Canfield*, Jeffrey R. Reimers* and Maxwell J. Crossley*,
The term “polytopal rearrangement” describes any shape changing process operating on a coordination “polyhedron”─the solid figure defined by the positions of the ligand atoms directly attached to the central atom of a coordination entity. Developed in the latter third of the last century, the polytopal rearrangement model of stereoisomerization is a general mathematical approach for analyzing and accommodating the complexity of such processes for any coordination number. The motivation for the model was principally to deal with the complexity, such as Berry pseudorotation in pentavalent phosphorus species, arising from rearrangements in inorganic coordination complexes of higher coordination numbers. The model is also applicable to lower coordination centers, for example, thermal “inversion” at nitrogen in NH3 and amines. We present the history of the model focusing on its essential features, and review some of the more subtle aspects addressed in recent literature. We then introduce a more detailed and rigorous modern approach for describing such processes using an assembly of existing concepts, with the addition of formally described terminology and representations. In our outlook, we contend that the rigorous and exhaustive application of the principles of the polytopal rearrangement model, when combined with torsional isomerism, will provide a basis for a mathematically complete, general, and systematic classification for all stereoisomerism and stereoisomerization. This is essential for comprehensively mapping chemical structure and reaction spaces.
{"title":"“Polytopal Rearrangement Model of Stereoisomerization” and Its Potential as the Basis for a Systematic Model of All Stereoisomerism","authors":"Peter J. Canfield*, Jeffrey R. Reimers* and Maxwell J. Crossley*, ","doi":"10.1021/acsorginorgau.4c0000510.1021/acsorginorgau.4c00005","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00005https://doi.org/10.1021/acsorginorgau.4c00005","url":null,"abstract":"<p >The term “polytopal rearrangement” describes any shape changing process operating on a coordination “polyhedron”─the solid figure defined by the positions of the ligand atoms directly attached to the central atom of a coordination entity. Developed in the latter third of the last century, the polytopal rearrangement model of stereoisomerization is a general mathematical approach for analyzing and accommodating the complexity of such processes for any coordination number. The motivation for the model was principally to deal with the complexity, such as Berry pseudorotation in pentavalent phosphorus species, arising from rearrangements in inorganic coordination complexes of higher coordination numbers. The model is also applicable to lower coordination centers, for example, thermal “inversion” at nitrogen in NH<sub>3</sub> and amines. We present the history of the model focusing on its essential features, and review some of the more subtle aspects addressed in recent literature. We then introduce a more detailed and rigorous modern approach for describing such processes using an assembly of existing concepts, with the addition of formally described terminology and representations. In our outlook, we contend that the rigorous and exhaustive application of the principles of the polytopal rearrangement model, when combined with torsional isomerism, will provide a basis for a mathematically complete, general, and systematic classification for all stereoisomerism and stereoisomerization. This is essential for comprehensively mapping chemical structure and reaction spaces.</p>","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsorginorgau.4c00005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141959248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-26DOI: 10.1021/acsorginorgau.4c00005
Peter J. Canfield, Jeffrey R. Reimers, Maxwell J. Crossley
The term “polytopal rearrangement” describes any shape changing process operating on a coordination “polyhedron”─the solid figure defined by the positions of the ligand atoms directly attached to the central atom of a coordination entity. Developed in the latter third of the last century, the polytopal rearrangement model of stereoisomerization is a general mathematical approach for analyzing and accommodating the complexity of such processes for any coordination number. The motivation for the model was principally to deal with the complexity, such as Berry pseudorotation in pentavalent phosphorus species, arising from rearrangements in inorganic coordination complexes of higher coordination numbers. The model is also applicable to lower coordination centers, for example, thermal “inversion” at nitrogen in NH3 and amines. We present the history of the model focusing on its essential features, and review some of the more subtle aspects addressed in recent literature. We then introduce a more detailed and rigorous modern approach for describing such processes using an assembly of existing concepts, with the addition of formally described terminology and representations. In our outlook, we contend that the rigorous and exhaustive application of the principles of the polytopal rearrangement model, when combined with torsional isomerism, will provide a basis for a mathematically complete, general, and systematic classification for all stereoisomerism and stereoisomerization. This is essential for comprehensively mapping chemical structure and reaction spaces.
{"title":"“Polytopal Rearrangement Model of Stereoisomerization” and Its Potential as the Basis for a Systematic Model of All Stereoisomerism","authors":"Peter J. Canfield, Jeffrey R. Reimers, Maxwell J. Crossley","doi":"10.1021/acsorginorgau.4c00005","DOIUrl":"https://doi.org/10.1021/acsorginorgau.4c00005","url":null,"abstract":"The term “polytopal rearrangement” describes any shape changing process operating on a coordination “polyhedron”─the solid figure defined by the positions of the ligand atoms directly attached to the central atom of a coordination entity. Developed in the latter third of the last century, the polytopal rearrangement model of stereoisomerization is a general mathematical approach for analyzing and accommodating the complexity of such processes for any coordination number. The motivation for the model was principally to deal with the complexity, such as Berry pseudorotation in pentavalent phosphorus species, arising from rearrangements in inorganic coordination complexes of higher coordination numbers. The model is also applicable to lower coordination centers, for example, thermal “inversion” at nitrogen in NH<sub>3</sub> and amines. We present the history of the model focusing on its essential features, and review some of the more subtle aspects addressed in recent literature. We then introduce a more detailed and rigorous modern approach for describing such processes using an assembly of existing concepts, with the addition of formally described terminology and representations. In our outlook, we contend that the rigorous and exhaustive application of the principles of the polytopal rearrangement model, when combined with torsional isomerism, will provide a basis for a mathematically complete, general, and systematic classification for all stereoisomerism and stereoisomerization. This is essential for comprehensively mapping chemical structure and reaction spaces.","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140311639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-22DOI: 10.1021/acsorginorgau.3c00066
Clarabella J. Li, Joseph W. Ziller, Jeffrey M. Barlow, Jenny Y. Yang
Escalating levels of carbon dioxide (CO2) in the atmosphere have motivated interest in CO2 capture and concentration from dilute streams. A guanidino-functionalized aromatic 1,4-bis(tetramethylguanidino)benzene (1,4-btmgb) was evaluated both as a redox-active sorbent and as a pH swing mediator for electrochemical CO2 capture and concentration. Spectroscopic and crystallographic studies demonstrate that 1,4-btmgb reacts with CO2 in water to form 1,4-btmgbH2(HCO3–)2. The product suggests that 1,4-btmgb could be used in an aqueous redox pH swing cycle for the capture and concentration of CO2. The synthesis and characterization of the mono- and diprotonated forms (1,4-btmgbH+ and 1,4-btmgbH22+) and their pKa values were measured to be 13.5 and 11.0 in water, respectively. Electrochemical pH swing experiments indicate the formation of an intermediate radical species and other degradation pathways, which ultimately inhibited fully reversible redox-induced pH cycling.
{"title":"Aqueous Electrochemical and pH Studies of Redox-Active Guanidino Functionalized Aromatics for CO2 Capture","authors":"Clarabella J. Li, Joseph W. Ziller, Jeffrey M. Barlow, Jenny Y. Yang","doi":"10.1021/acsorginorgau.3c00066","DOIUrl":"https://doi.org/10.1021/acsorginorgau.3c00066","url":null,"abstract":"Escalating levels of carbon dioxide (CO<sub>2</sub>) in the atmosphere have motivated interest in CO<sub>2</sub> capture and concentration from dilute streams. A guanidino-functionalized aromatic 1,4-bis(tetramethylguanidino)benzene (1,4-btmgb) was evaluated both as a redox-active sorbent and as a pH swing mediator for electrochemical CO<sub>2</sub> capture and concentration. Spectroscopic and crystallographic studies demonstrate that 1,4-btmgb reacts with CO<sub>2</sub> in water to form 1,4-btmgbH<sub>2</sub>(HCO<sub>3</sub><sup>–</sup>)<sub>2</sub>. The product suggests that 1,4-btmgb could be used in an aqueous redox pH swing cycle for the capture and concentration of CO<sub>2</sub>. The synthesis and characterization of the mono- and diprotonated forms (1,4-btmgbH<sup>+</sup> and 1,4-btmgbH<sub>2</sub><sup>2+</sup>) and their p<i>K</i><sub>a</sub> values were measured to be 13.5 and 11.0 in water, respectively. Electrochemical pH swing experiments indicate the formation of an intermediate radical species and other degradation pathways, which ultimately inhibited fully reversible redox-induced pH cycling.","PeriodicalId":29797,"journal":{"name":"ACS Organic & Inorganic Au","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140202656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}