“Arm-first” approach for the synthesis of star-shaped stereoregular polymers through living coordination polymerization

2017 ◽  
Vol 8 (9) ◽  
pp. 1449-1453 ◽  
Author(s):  
Zhenghai Shi ◽  
Fang Guo ◽  
Rui Tan ◽  
Hui Niu ◽  
Tingting Li ◽  
...  
Keyword(s):  
Star Polymers ◽  
Catalyst System ◽  
Coordination Polymerization ◽  
Polymerization Mechanism ◽  
System P ◽  
Stereoregular Polymers ◽  
First Time ◽  
Half Sandwich

Stereoregular star polymers were synthesized through an “arm-first” approach via a living coordination polymerization mechanism for the first time using a half-sandwich scandium catalyst system.

Modular construction of multifunctional ligands for the enantioselective ruthenium-catalyzed carbenoid N–H insertion reaction: an enzyme-like and substrate-sensitive catalyst system

RSC Advances ◽  
2015 ◽  
Vol 5 (58) ◽  
pp. 46455-46463 ◽  
Author(s):  
Wei-Sheng Huang ◽  
Zheng Xu ◽  
Ke-Fang Yang ◽  
Li Chen ◽  
Zhan-Jiang Zheng ◽  
...  
Keyword(s):  
Catalyst System ◽  
Insertion Reaction ◽  
Modular Construction ◽  
System P ◽  
Silicon Based ◽  
First Time ◽  
Multifunctional Ligands

It was found for the first time that BINOL-derived multifunctional ligands bearing a silicon-based bulky group exhibited promising enantioselective control in the ruthenium-catalysed carbenoid N–H insertion reaction.

Effect of pressure on synthetic diamond crystals at high temperatures and pressures in Fe/Ni catalyst system

CrystEngComm ◽  
2021 ◽  
Author(s):  
Shuai Fang ◽  
Yongkui Wang ◽  
Liangchao Chen ◽  
Zhiyun Lu ◽  
Zhenghao Cai ◽  
...  
Keyword(s):  
Nitrogen Content ◽  
Growth Mechanism ◽  
Synthetic Diamond ◽  
Natural Diamond ◽  
Catalyst System ◽  
Necessary Condition ◽  
Ni Catalyst ◽  
Effect Of Pressure ◽  
Diamond Crystals ◽  
System P

Pressure is a necessary condition for the growth of natural diamond. Studying the effect of pressure on the nitrogen content of diamond is important for exploring the growth mechanism of...

A novel enantioselective synthesis of 6H-dibenzopyran derivatives by combined palladium/norbornene and cinchona alkaloid catalysis

2015 ◽  
Vol 13 (8) ◽  
pp. 2260-2263 ◽  
Author(s):  
Di Xu ◽  
Li Dai ◽  
Marta Catellani ◽  
Elena Motti ◽  
Nicola Della Ca’ ◽  
...  
Keyword(s):  
Catalytic System ◽  
Enantioselective Synthesis ◽  
Cinchona Alkaloid ◽  
System P ◽  
First Time

Chiral dibenzopyran derivatives were obtained by cinchona alkaloid, as organocatalyst, in combination, for the first time, with palladium/norbornene catalytic system.

Systems theory

2017 ◽  
Author(s):  
Anastasia Marinopoulou
Keyword(s):  
Systems Theory ◽  
Multiple Realities ◽  
Traditional Epistemology ◽  
System P ◽  
History Of ◽  
Scientific Truth ◽  
Scientific System ◽  
First Time ◽  
Methodology Of Science ◽  
Scientific Purpose

In his systems’ theory, Luhmann attempts to redefine communication, and associates it with information. For Luhmann, communication is distinct from action (Handeln), and the rationality of the scientific system resides in the notion of Zweck, or in the ends of the sciences towards action. For the first time in the epistemological history of modernity, rationality is understood as a certain scientific purpose of action and not as the critique of scientific truth and validity of reason. The schism that Luhmann brought about between ‘traditional’ epistemology (reconsidered now as novel) and the ‘critical’ theory of science (seen by Luhmann as ‘traditional’) was irredeemable. In the following pages, I maintain that all evidence to the contrary such a divergence was inherent to modernity.Drawing on the Schützean model of multiple realities, Luhmann manages to blur the distinction between instrumentality and rationality by relativizing both within systemic complexity. According to Luhmann, complexity characterizes a multifaceted social system, such as science itself. However, I argue that where complexity, in Luhmann, interprets the systemic, it also employs presentism and partial situationalism to explain the essence and methodology of science as a system.

From Dalton to the Discovery of the Periodic System

2013 ◽  
Author(s):  
Eric Scerri
Keyword(s):  
Periodic System ◽  
Quantitative Data ◽  
Quantitative Characteristic ◽  
Good Deal ◽  
Ancient Greek ◽  
System P ◽  
Quantitative Property ◽  
To Come ◽  
First Time

Our story begins, somewhat arbitrarily, in the English city of Manchester around the turn of the nineteenth century. There, a child prodigy by the name of John Dalton, at the tender age of fifteen is teaching in a school with his older brother. Within a few years, John Dalton’s interests have developed to encompass meteorology, physics, and chemistry. Among the questions that puzzle him is why the various component gases in the air such as oxygen, nitrogen, and carbon dioxide do not separate from each other. Why does the mixture of gases in the air remain as a homogeneous mixture? As a result of pursuing this question, Dalton develops what is to become modern atomic theory. The ultimate constituents of all substances, he supposes, are hard microscopic spheres or atoms that were first discussed by the ancient Greek philosophers and taken up again by modern scientists like Newton, Gassendi, and Boscovich. But Dalton goes a good deal further than all of these thinkers in establishing one all-important quantitative characteristic for each kind of atom, namely its weight. This he does by considering quantitative data on chemical experiments. For example, he finds that the ratio for the weight in which hydrogen and oxygen combine together is one to eight. Dalton assumes that water consists of one atom of each of these two elements. He takes a hydrogen atom to have a weight of 1 unit and therefore reasons that oxygen must have a weight of 8 units. Similarly, he deduces the weights for a number of other atoms and even molecules as we now call them. For the first time the elements acquire a quantitative property, by means of which they may be compared. This feature will eventually lead to an accurate classification of all the elements in the form of the periodic system, but this is yet to come. Before that can happen the notion of atoms provokes tremendous debates and disagreements among the experts of Dalton’s day.

scholarly journals Trends and Exceptions in the Interaction of Hydroxamic Acid Derivatives of Common Di- and Tripeptides with Some 3d and 4d Metal Ions in Aqueous Solution

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3941 ◽  
Author(s):  
Ozsváth ◽  
Bíró ◽  
Nagy ◽  
Buglyó ◽  
Sanna ◽  
...  
Keyword(s):  
Metal Ions ◽  
Hydroxamic Acid ◽  
Hydroxamic Acids ◽  
17O Nmr ◽  
Equilibrium Study ◽  
Sandwich Type ◽  
Uv Visible ◽  
First Time ◽  
Derivatives Of ◽  
Half Sandwich

By using various techniques (pH-potentiometry, UV-Visible spectrophotometry, 1H and 17O-NMR, EPR, ESI-MS), first time in the literature, solution equilibrium study has been performed on complexes of dipeptide and tripeptide hydroxamic acids—AlaAlaNHOH, AlaAlaN(Me)OH, AlaGlyGlyNHOH, and AlaGlyGlyN(Me)OH—with 4d metals: the essential Mo(VI) and two half-sandwich type cations, [(η6-p-cym)Ru(H2O)3]2+ as well as [(η5-Cp*)Rh(H2O)3]2+, the latter two having potential importance in cancer therapy. The tripeptide derivatives have also been studied with some biologically important 3d metals, such as Fe(III), Ni(II), Cu(II), and Zn(II), in order to compare these new results with the corresponding previously obtained ones on dipeptide hydroxamic acids. Based on the outcomes, the effects of the type of metal ions, the coordination number, the number and types of donor atoms, and their relative positions to each other on the complexation have been evaluated in the present work. We hope that these collected results might be used when a new peptide-based hydroxamic acid molecule is planned with some purpose, e.g. to develop a potential metalloenzyme inhibitor.

Construction of polyphosphoesters with the main chain of rigid backbones and stereostructures via organocatalyzed ring-opening polymerization

2020 ◽  
Vol 11 (20) ◽  
pp. 3475-3480
Author(s):  
Yu-Jia Zheng ◽  
Guan-Wen Yang ◽  
Bo Li ◽  
Guang-Peng Wu
Keyword(s):  
Ring Opening ◽  
Main Chain ◽  
Catalyst System ◽  
Ring Opening Polymerization ◽  
System P ◽  
Organic Catalyst

A highly stereoregular polyphosphoester with a rigid cyclohexylene structure in the main chain was constructed via ring-opening polymerization (ROP) in the presence of an organic catalyst system.

Autocatalytic amplified detection of DNA based on a CdSe quantum dot/folic acid electrochemiluminescence energy transfer system

The Analyst ◽  
2015 ◽  
Vol 140 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Guifen Jie ◽  
Yingqiang Qin ◽  
Qingmin Meng ◽  
Jialin Wang
Keyword(s):  
Energy Transfer ◽  
Folic Acid ◽  
Quantum Dot ◽  
Transfer System ◽  
Cdse Qds ◽  
System P ◽  
Cdse Quantum Dot ◽  
Autocatalytic System ◽  
First Time

Electrochemiluminescence energy transfer from CdSe QDs to folic acid was applied for the first time for amplified detection of DNA by a DNAzyme autocatalytic system.

Highly trans-1,4-stereoselective coordination chain transfer polymerization of 1,3-butadiene and copolymerization with cyclic esters by a neodymium-based catalyst system

2015 ◽  
Vol 6 (33) ◽  
pp. 6088-6095 ◽  
Author(s):  
Wenjie Zheng ◽  
Nan Yan ◽  
Yutian Zhu ◽  
Wenpeng Zhao ◽  
Chunyu Zhang ◽  
...  
Keyword(s):  
Chain Transfer ◽  
Catalyst System ◽  
Amphiphilic Copolymers ◽  
Cyclic Esters ◽  
System P ◽  
Chain Transfer Polymerization

Highly trans-1,4-stereoregular polybutadiene (TPB) was obtained by CCTP and novel amphiphilic copolymers (TPB-b-PCL/PLA) were successfully synthesized.

scholarly journals Robust Buchwald–Hartwig amination enabled by ball-milling

2019 ◽  
Vol 17 (7) ◽  
pp. 1722-1726 ◽  
Author(s):  
Qun Cao ◽  
William I. Nicholson ◽  
Andrew C. Jones ◽  
Duncan L. Browne
Keyword(s):  
Ball Milling ◽  
Catalyst System ◽  
Secondary Amines ◽  
Mechanochemical Method ◽  
System P

An operationally simple mechanochemical method for the Pd catalysed Buchwald–Hartwig amination of arylhalides with secondary amines has been developed using a Pd PEPPSI catalyst system.

Sign in / Sign up

Export Citation Format

Share Document