Model studies of the sequential and simultaneous statistical modification of dendritic functional groups and their implications within complex polymer architecture synthesis

2017 ◽  
Vol 8 (10) ◽  
pp. 1644-1653 ◽  
Author(s):  
Faye Y. Hern ◽  
Sam E. R. Auty ◽  
Oliver C. J. Andrén ◽  
Michael Malkoch ◽  
Steve P. Rannard
Keyword(s):  
Functional Groups ◽  
Model Systems ◽  
Polymer Architecture ◽  
Nmr Studies ◽  
Accurate Analysis ◽  
Model Studies ◽  
Maldi Tof ◽  
Polymer Architectures ◽  
Post Synthesis ◽  
Complex Polymer

Accurate analysis of model systems by MALDI-TOF has established the diversity of structures formed during post-synthesis functionalisation of complex polymer architectures. NMR studies alone are shown to be highly misleading.

TiCp2Cl-Catalyzed Living Radical and Ring Opening Polymerizations Initiated from Epoxides and Aldehydes in the Synthesis of Linear, Graft and Branched Polymers

2004 ◽  
Vol 856 ◽  
Author(s):  
Alexandru D. Asandei ◽  
Isaac W. Moran ◽  
Gobinda Saha ◽  
Yanhui Chen
Keyword(s):  
Electron Transfer ◽  
Ring Opening ◽  
Glycidyl Methacrylate ◽  
Ring Opening Polymerization ◽  
Branched Polymers ◽  
Single Electron Transfer ◽  
Radical Ring ◽  
Polymer Architectures ◽  
Complex Polymer

ABSTRACTTi(III)Cp2Cl-catalyzed radical ring opening (RRO) of epoxides or single electron transfer (SET) reduction of aldehydes generates Ti alkoxides and carbon centered radicals which add to styrene, initiating a radical polymerization. This polymerization is mediate in a living fashion by the reversible termination of growing chains with the TiCp2Cl metalloradical. In addition, polymers or monomers containing pendant epoxide groups (glycidyl methacrylate) can be used as substrates for radical grafting or branching reactions by self condensing vinyl polymerization. In addition, Ti alkoxides generated in situ by both epoxide RRO and aldehyde SET initiate the living ring opening polymerization of ε-caprolactone. Thus, new initiators and catalysts are introduced for the synthesis of complex polymer architectures.

scholarly journals Efficient click-addition sequence for polymer–polymer couplings

2016 ◽  
Vol 7 (35) ◽  
pp. 5536-5543 ◽  
Author(s):  
Johannes C. Brendel ◽  
Guillaume Gody ◽  
Sébastien Perrier
Keyword(s):  
Click Chemistry ◽  
Radical Polymerization ◽  
Controlled Radical Polymerization ◽  
Polymer Architectures ◽  
Complex Polymer

Controlled radical polymerization methods and click chemistry form a versatile toolbox for creating complex polymer architectures.

scholarly journals Corrosion Inhibition Mechanism and Efficiency Differentiation of Dihydroxybenzene Isomers Towards Aluminum Alloy 5754 in Alkaline Media

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3067 ◽  
Author(s):  
Ryl ◽  
Brodowski ◽  
Kowalski ◽  
Lipinska ◽  
Niedzialkowski ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Functional Groups ◽  
Alkaline Media ◽  
Aluminum Surface ◽  
Inhibition Mechanism ◽  
Detailed Knowledge ◽  
Nmr Studies ◽  
Bicarbonate Buffer ◽  
Dihydroxybenzene Isomers ◽  
Aluminum Alloy 5754

The selection of efficient corrosion inhibitors requires detailed knowledge regarding the interaction mechanism, which depends on the type and amount of functional groups within the inhibitor molecule. The position of functional groups between different isomers is often overlooked, but is no less important, since factors like steric hinderance may significantly affect the adsorption mechanism. In this study, we have presented how different dihydroxybenzene isomers interact with aluminum alloy 5754 surface, reducing its corrosion rate in bicarbonate buffer (pH = 11). We show that the highest inhibition efficiency among tested compounds belongs to catechol at 10 mM concentration, although the differences were moderate. Utilization of novel impedance approach to adsorption isotherm determination made it possible to confirm that while resorcinol chemisorbs on aluminum surface, catechol and quinol follows the ligand exchange model of adsorption. Unlike catechol and quinol, the protection mechanism of resorcinol is bound to interaction with insoluble aluminum corrosion products layer and was only found efficient at concentration of 100 mM (98.7%). The aforementioned studies were confirmed with Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy analyses. There is a significant increase in the corrosion resistance offered by catechol at 10 mM after 24 h exposure in electrolyte: from 63 to 98%, with only negligible changes in inhibitor efficiency observed for resorcinol at the same time. However, in the case of resorcinol a change in electrolyte color was observed. We have revealed that the differentiating factor is the keto-enol tautomerism. The Nuclear Magnetic Resonance (NMR) studies of resorcinol indicate the keto form in structure in presence of NaOH, while the chemical structure of catechol does not change significantly in alkaline environment.

scholarly journals Dissecting the Fine Details of Assembly of aT = 3 Phage Capsid

2005 ◽  
Vol 6 (2) ◽  
pp. 119-125 ◽  
Author(s):  
P. G. Stockley ◽  
A. E. Ashcroft ◽  
S. Francese ◽  
G. S. Thompson ◽  
N. A. Ranson ◽  
...  
Keyword(s):  
Rna Binding ◽  
Protein Complexes ◽  
Model Systems ◽  
Replicase Gene ◽  
Nmr Studies ◽  
Partial Explanation ◽  
Stem Loop ◽  
Assembly Pathway

The RNA bacteriophages represent ideal model systems in which to probe the detailed assembly pathway for the formation of aT = 3 quasi-equivalent capsid. For MS2, the assembly reaction can be probedin vitrousing acid disassembled coat protein subunits and a short (19 nt) RNA stem-loop that acts as the translational operator of the replicase gene and leads to sequence-specific sequestration and packaging of the cognate phage RNAin vivo. Reassembly reactions can be initiated by mixing these components at neutral pH. The molecular basis of the sequence-specific RNA–protein interaction is now well understood. Recent NMR studies on the protein demonstrate extensive mobility in the loops of the polypeptide that alter their conformations to form the quasi-equivalent conformers of the final capsid. It seems reasonable to assume that RNA binding results in reduction of this flexibility. However, mass spectrometry suggests that these RNA–protein complexes may only provide one type of quasi-equivalent capsid building block competent to form five-fold axes but not the full shell. Work with longer RNAs suggests that the RNA may actively template the assembly pathway providing a partial explanation of how conformers are selected in the growing shell.

Synthesis of phthalocyanine compounds bearing 2-(diethoxyphosphoryl)-4-methylpenta-1,3-dienyl functional groups

2013 ◽  
Vol 17 (05) ◽  
pp. 343-350 ◽  
Author(s):  
Alexander Yu. Tolbin ◽  
Victor E. Pushkarev ◽  
Irina O. Balashova ◽  
Valery K. Brel ◽  
Yuliana I. Gudkova ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Functional Groups ◽  
Spectroscopy Data ◽  
Free Base ◽  
Maldi Tof Mass Spectrometry ◽  
Maldi Tof ◽  
First Time

Free-base phthalocyanine ligands and their zinc derivatives representing functionally monosubstituted (A3B type) or tetrasubstituted (A4 type) compounds with 2-diethoxyphosphoryl-4-methylpenta-1,3-dienyl moieties have been synthesized for the first time. Their structures were characterized by MALDI-TOF mass-spectrometry as well as 1 H and 31 P NMR spectroscopy data. A tendency to aggregation in dependence on the nature of the solvent was demonstrated as well.

NMR Studies of Coupled Low- and High-Barrier Hydrogen Bonds in Pyridoxal-5‘-phosphate Model Systems in Polar Solution

2007 ◽  
Vol 129 (19) ◽  
pp. 6313-6327 ◽  
Author(s):  
Shasad Sharif ◽  
Gleb S. Denisov ◽  
Michael D. Toney ◽  
Hans-Heinrich Limbach
Keyword(s):  
Hydrogen Bonds ◽  
Model Systems ◽  
Nmr Studies ◽  
Polar Solution

TEM Study of SiCN Glasses; Polymer Architecture versus Ceramic Microstructure

2008 ◽  
Vol 403 ◽  
pp. 153-156 ◽  
Author(s):  
Hans Joachim Kleebe ◽  
Heike Störmer
Keyword(s):  
High Temperature ◽  
Structural Features ◽  
Amorphous Structure ◽  
Bulk Materials ◽  
Polymer Architecture ◽  
High Temperature Anneal ◽  
Main Emphasis ◽  
Polymer Architectures ◽  
Ceramic Microstructure ◽  
Characteristic Features

Polymer-derived SiCN glasses with tailored polymer architectures were characterized by TEM and EF-SAED upon pyrolysis at 1000 °C and subsequent annealing. Main emphasis of this work was to verify as to whether the intrinsic amorphous structure of polymer-derived bulk materials exhibits different structural features upon pyrolysis, depending on the functionalities of the pre-ceramic polymer, and whether such characteristic features are maintained upon high-temperature anneal.

Molecular recognition: Model studies with convergent functional groups

1988 ◽  
Vol 1 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Julius Rebek
Keyword(s):  
Molecular Recognition ◽  
Functional Groups ◽  
Recognition Model ◽  
Model Studies

scholarly journals The cyclosporine transdermal transfer possibility study on model systems

2019 ◽  
Vol 21 (1) ◽  
pp. 135-141
Author(s):  
E. G. Kuznetsova ◽  
O. M. Kuryleva ◽  
L. A. Salomatina ◽  
V. Yu. Belov ◽  
V. I. Sevastianov
Keyword(s):  
Great Britain ◽  
Organ Transplantation ◽  
Blood Concentration ◽  
Model Systems ◽  
Therapeutic System ◽  
Liquid Chromatograph ◽  
Model Studies ◽  
Micro Hplc ◽  
Emulsion Matrix ◽  
Ultrasonic Homogenizer

Aim: to develop the emulsion transdermal therapeutic system (TTS) of cyclosporine and the research of its diffusion from TTS.Materials and methods. The quantitative evaluation of cyclosporine in model media was performed on liquid chromatograph Agilent 1100 G1311 with spectrophotometric detector G1315B (Germany). For the production of the emulsion matrix, the Heidolph DIAX900 disperser (Germany) and the ultrasonic homogenizer Hielscher UIS250V (Germany) were used. The cyclosporine diffusion from TTS through Strat-M membrane (25 mm in diameter, Merck Millipore) was studied using Copley diffusion analyser (Great Britain).Results. Using the developed method of micro-HPLC, it was established that the amount of cyclosporine passed through the Strat-M membrane over 24 hours from 10 sm2 TTS, containing 173 mg of the substance, was 5.9 mg. The estimated blood concentration is ~ 50 ng/ml which corresponds to the therapeutic maintenance blood concentration during organ transplantation (50–75 ng/ml).Conclusion. The model studies demonstrate the possibility of the cyclosporine transdermal transfer.

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