Teilisotaktisches Poly(hydroxybutyrat) aus racemischem β‐Butyrolacton: Mikrostrukturkontrolle durch achirale Chrom(III)‐Salophen‐Komplexe

Zintl, Manuela; Molnár, F.; Urban, Tobias; Bernhart, Volker; Preishuber‐Pflügl, Peter; Rieger, Bernhard

doi:10.1002/ange.200703859

Cited by 17 publications

(3 citation statements)

References 32 publications

(12 reference statements)

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“…The synthesis started by the condensation of bromo‐diaminobenzene 2 and salicylaldehyde 3 to yield salphen ligand 4 19 that precipitates in ethanol. Platinum was then coordinated to ligand 4 , by using K 2 PtCl 4 as a source of Pt II , to yield complex 5 .…”

Section: Resultsmentioning

confidence: 99%

Terpy(Pt–salphen)₂ Switchable Luminescent Molecular Tweezers

Doistau

Tron

Denisov

et al. 2014

Chemistry A European J

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The design and synthesis of switchable molecular tweezers based on a luminescent terpy(Pt-salphen)2 (1; terpy=terpyridine) complex is reported. Upon metal coordination, the tweezers can switch from an open "W"-shaped conformation to a closed "U"-shaped form that is adapted for selective recognition of cations. Closing of the tweezers by metal coordination (M=Zn(2+), Cu(2+), Pb(2+), Fe(2+), Hg(2+)) was monitored by (1)H NMR and/or UV/Vis titrations. During the titration, exclusive formation of the 1:1 complex [M(1)] was observed, without appearance of an intermediate 1:2 complex [M(1)2]. The crystallographic structure of the 1:1 complex was obtained with Pb(2+) and showed a distorted helical structure. Selective intercalation of Hg(2+) cations by the closed "U" form was observed. The tweezers were reopened by selective metal decoordination of the terpyridine ligand by using tris(2-aminoethyl)amine (tren) as a competitive ligand without modification of the Pt-salphen complex. Detailed photophysical studies were performed on the open and closed tweezers. Structured emission was observed in the open form from the Pt-salphen moieties, with a high quantum yield and a long lifetime. The emission is slightly modified upon closing with 1 equivalent of Zn(2+) or Hg(2+), whereas a dramatic quenching was obtained upon intercalation of additional Hg(2+).

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Section: Resultsmentioning

confidence: 99%

Terpy(Pt–salphen)₂ Switchable Luminescent Molecular Tweezers

Doistau

Tron

Denisov

et al. 2014

Chemistry A European J

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“…Polycarbonates, derived from epoxides and CO 2 , and poly(hydroxybutyrate) (PHB), are promising examples of thermoplastic polymers that can be synthesized independent of petroleum resources . Both polymerization reactions are efficiently catalyzed by discrete, homogeneous, and metal-based complexes; , however, there are only a few examples of catalysts that are able to perform both reactions. , Despite the high internal strain of the four-membered butyrolactone ring, BBL seems to be a rather reluctant monomer, as it is less reactive than lactide (LA) or ε-caprolactone (ε-CL). , Natural PHB is commonly strictly ( R )-isotactic and is a highly crystalline thermoplastic material . Through metal-catalyzed ROP of BBL, syndiotactic, atactic, or slightly isotactic enriched PHB can be obtained, depending on the nature of the employed catalyst. ,,, A key challenge in polymer chemistry is the realization of polymerizations from a mixed monomer feedstock and the chemoselective control of the incorporation of the monomers to regulate the polymer structure and consequently the thermal and mechanical properties, as demonstrated by recent reports .…”

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confidence: 99%

CO₂-Controlled One-Pot Synthesis of AB, ABA Block, and Statistical Terpolymers from β-Butyrolactone, Epoxides, and CO₂

et al. 2017

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Terpolymerizations of (rac)-β-butyrolactone (BBL), cyclohexene oxide (CHO), and carbon dioxide were realized in one-pot reactions utilizing a Lewis acid BDI-Zn-N(SiMe) (1) catalyst. The type of polymerization can be regulated and switched between ring-opening polymerization (ROP) of BBL and CHO/CO copolymerization by the presence of CO in the reaction mixture. Applying 3 bar CO to the three-component system leads to similar reaction rates for copolymerization and ROP and therefore to a terpolymer with a statistical composition, whereas 40 bar CO affords exclusive copolymerization of CHO/CO. Two-dimensional NMR spectroscopy and polarimetry provided a deeper understanding of the underlying mechanism. Furthermore, copolymerization of cyclopentene oxide (CPO) and CO was performed, resulting in the highest reported TOF of 3200 h together with 99% polycarbonate selectivity. Terpolymerizations of CPO/CO and BBL were successfully conducted using the established reaction pathways.

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“…The reaction proceeds via subsequent CO insertion into the CoC bond, CO addition to the Co‐center and ring closure. Another paper presents Cr catalysts with salophen ligands for the ring opening polymerization step of racemic β‐butyro lactone leading to an isotactically enriched material via chain end control . It is postulated that the reaction proceeds in a dinuclear manner and that growing polymer chains are carboxylate terminated.…”

Section: Chemical Reactivity and Catalysismentioning

confidence: 99%

Application of quantum calculations in the chemical industry—An overview

Deglmann¹,

Schäfer²,

Lennartz³

2014

Int J of Quantum Chemistry

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The field of quantum chemistry experienced huge progress in the past two decades. The drivers for this have been the availability of more and more powerful computer hardware, the development and implementation of improved methods with a better balanced compromise between accuracy and efficiency, as well as pioneering work how these methods are successfully applied to real-world problems. Thus, quantum calculations, in particular via density functional theory, became an essential tool in many branches of chemical research. This article tries to give an overview how quantum chemical modeling is used in chemical industry, which is done by reviewing papers written by authors from chemical companies. Various topics of particular industrial relevance are introduced together with strategies how to address them via quantum calculations. Examples are the computation of reaction thermodynamics and kinetics as the key ingredients to understand and predict chemical reactivity, but also solvation models as well as methods to describe electronically excited states.

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Teilisotaktisches Poly(hydroxybutyrat) aus racemischem β‐Butyrolacton: Mikrostrukturkontrolle durch achirale Chrom(III)‐Salophen‐Komplexe

Cited by 17 publications

References 32 publications

Terpy(Pt–salphen)₂ Switchable Luminescent Molecular Tweezers

Terpy(Pt–salphen)₂ Switchable Luminescent Molecular Tweezers

CO₂-Controlled One-Pot Synthesis of AB, ABA Block, and Statistical Terpolymers from β-Butyrolactone, Epoxides, and CO₂

Application of quantum calculations in the chemical industry—An overview

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Teilisotaktisches Poly(hydroxybutyrat) aus racemischem β‐Butyrolacton: Mikrostrukturkontrolle durch achirale Chrom(III)‐Salophen‐Komplexe

Cited by 17 publications

References 32 publications

Terpy(Pt–salphen)2 Switchable Luminescent Molecular Tweezers

Terpy(Pt–salphen)2 Switchable Luminescent Molecular Tweezers

CO2-Controlled One-Pot Synthesis of AB, ABA Block, and Statistical Terpolymers from β-Butyrolactone, Epoxides, and CO2

Application of quantum calculations in the chemical industry—An overview

Contact Info

Product

Resources

About

Terpy(Pt–salphen)₂ Switchable Luminescent Molecular Tweezers

Terpy(Pt–salphen)₂ Switchable Luminescent Molecular Tweezers

CO₂-Controlled One-Pot Synthesis of AB, ABA Block, and Statistical Terpolymers from β-Butyrolactone, Epoxides, and CO₂