scholarly journals An Efficient Synthesis of [n]Cycloparaphenylenes (n = 9, 12, 15) via the Self-Assembly into Macrocyclic Gold(I)-Oligophenylene Complexes Based on Dynamic Au–C σ-Bonds

2021 ◽  
Author(s):  
Yohei Tanji ◽  
Yusuke Yoshigoe ◽  
Shinichi Saito ◽  
Kohtaro Osakada ◽  
Yoshitaka Tsuchido ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Self Assembly ◽  
Macrocyclic Complexes ◽  
The Self ◽  
Kinetics Study ◽  
Efficient Synthesis ◽  
Gold Complexes ◽  
Oxidative Chlorination

The transmetalation of the digold(I) complex [Au2Cl2(Cy2PCH2PCy2)] with oligophenylene diboronic acids gave the triangu-lar macrocyclic complexes [Au2(C6H4)x(Cy2PCH2PCy2)]3 (x = 3, 4, 5) with yields of over 70%. A series of [n]cycloparaphenylenes (n = 9, 12, 15) was isolated in 78–88% yield via the oxidative chlorination of the macrocyclic gold complexes. A kinetics study employing two acyclic dinuclear gold(I) complexes, [Au2R2(Cy2PCH2PCy2)] (R = Ph and/or C6H4-4-F), revealed that an intermolecular Au(I)–C σ-bond-exchange reaction proceeded. These results indicate that the trian-gular complexes were obtained selectively via reversible intermolecular Au(I)–C σ-bond exchanges. By reacting two different oligophenylene diboronic acids with the digold(I) complex, a mixture of macrocyclic complexes incorporating different oli-gophenylene linkers was formed. The oxidative chlorination of this mixture gave [n]cycloparaphenylenes with various num-bers of phenylene units.

Efficient synthesis and self-assembly of hetero-grafted amphiphilic polypepide bottlebrushes

2012 ◽  
Vol 84 (12) ◽  
pp. 2569-2578 ◽  
Author(s):  
Chunhui Luo ◽  
Chongyi Chen ◽  
Zhibo Li
Keyword(s):  
Self Assembly ◽  
Ring Opening ◽  
Click Reaction ◽  
Ring Opening Polymerization ◽  
The Self ◽  
Molar Ratio ◽  
Efficient Synthesis ◽  
Poly Ethylene Glycol ◽  
New Type ◽  
Poly Ethylene

A new type of hetero-grafted molecular bottlebrush with polypeptide as backbone was synthesized using graft-onto strategy. Poly(γ-propargyl-L-glutamate) (PPLG) as backbone was firstly synthesized via ring-opening polymerization (ROP) of γ-propargyl-L-glutamate (PLG) N-carboxyanhydride (NCA). Next, polystyrene-N3 (PS-N3) and monomethoxy poly(ethylene glycol)-N3 (mPEG-N3) as side chains were grafted onto the PPLG backbone using copper-catalyzed click reaction, which afforded good grafting density and efficiency. Two polypeptide bottlebrushes with PS-to-mPEG molar ratio at 70/30 and 30/70 were prepared. The self-assembly behaviors of these two polypeptide bottlebrushes were investigated using the cosolvent method, and their supramolecular structures were characterized using light scattering (LS) and electron microscopy.

The Nature of Rapidly Extracted Phycocyanin from the Blue-Green Alga Plectonema Boryanum

1971 ◽  
Vol 29 ◽  
pp. 366-367
Author(s):  
M. Kessel ◽  
R. MacColl
Keyword(s):  
Self Assembly ◽  
Analytical Ultracentrifugation ◽  
Uranyl Acetate ◽  
The Self ◽  
Major Protein ◽  
Subunit Structure ◽  
Blue Green Alga ◽  
Thin Sections ◽  
Blue Green Algae ◽  
Cacodylate Buffer

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.

Interrelationship of the cellular distribution and secretion of regular structure (RS) protein in Bacillus licheniformis nm 105

1992 ◽  
Vol 50 (1) ◽  
pp. 712-713
Author(s):  
Xiaorong Zhu ◽  
Richard McVeigh ◽  
Bijan K. Ghosh
Keyword(s):  
Alkaline Phosphatase ◽  
Bacillus Licheniformis ◽  
Self Assembly ◽  
Gel Electrophoresis ◽  
Culture Supernatant ◽  
Regular Structure ◽  
The Self ◽  
Cellular Distribution ◽  
Structural Protein ◽  
Laboratory Cultures

A mutant of Bacillus licheniformis 749/C, NM 105 exhibits some notable properties, e.g., arrest of alkaline phosphatase secretion and overexpression and hypersecretion of RS protein. Although RS is known to be widely distributed in many microbes, it is rarely found, with a few exceptions, in laboratory cultures of microorganisms. RS protein is a structural protein and has the unusual properties to form aggregate. This characteristic may have been responsible for the self assembly of RS into regular tetragonal structures. Another uncommon characteristic of RS is that enhanced synthesis and secretion which occurs when the cells cease to grow. Assembled RS protein with a tetragonal structure is not seen inside cells at any stage of cell growth including cells in the stationary phase of growth. Gel electrophoresis of the culture supernatant shows a very large amount of RS protein in the stationary culture of the B. licheniformis. It seems, Therefore, that the RS protein is cotranslationally secreted and self assembled on the envelope surface.

Nanoscale Self-Assembly Using Ion and Electron Beam Techniques: A Rapid Review

MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3507-3520
Author(s):  
Chunhui Dai ◽  
Kriti Agarwal ◽  
Jeong-Hyun Cho
Keyword(s):  
Electron Beam ◽  
Self Assembly ◽  
Ion Beam ◽  
Three Dimensional ◽  
The Self ◽  
Stress Generation ◽  
Rapid Review ◽  
High Yield ◽  
3D Nanostructures ◽  
Self Assembled

AbstractNanoscale self-assembly, as a technique to transform two-dimensional (2D) planar patterns into three-dimensional (3D) nanoscale architectures, has achieved tremendous success in the past decade. However, an assembly process at nanoscale is easily affected by small unavoidable variations in sample conditions and reaction environment, resulting in a low yield. Recently, in-situ monitored self-assembly based on ion and electron irradiation has stood out as a promising candidate to overcome this limitation. The usage of ion and electron beam allows stress generation and real-time observation simultaneously, which significantly enhances the controllability of self-assembly. This enables the realization of various complex 3D nanostructures with a high yield. The additional dimension of the self-assembled 3D nanostructures opens the possibility to explore novel properties that cannot be demonstrated in 2D planar patterns. Here, we present a rapid review on the recent achievements and challenges in nanoscale self-assembly using electron and ion beam techniques, followed by a discussion of the novel optical properties achieved in the self-assembled 3D nanostructures.

Bottom-up Evolution from Disks to High-Genus Polymersomes

2018 ◽  
Author(s):  
Claudia Contini ◽  
Russell Pearson ◽  
Linge Wang ◽  
Lea Messager ◽  
Jens Gaitzsch ◽  
...  
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Amphiphilic Copolymers ◽  
Chain Entanglement ◽  
Bottom Up ◽  
New Approach ◽  
High Genus ◽  
Transmission Electron ◽  
Minimal Radius ◽  
Stop Flow

<div><div><div><p>We report the design of polymersomes using a bottom-up approach where the self-assembly of amphiphilic copolymers poly(2-(methacryloyloxy) ethyl phosphorylcholine)–poly(2-(diisopropylamino) ethyl methacrylate) (PMPC-PDPA) into membranes is tuned using pH and temperature. We study this process in detail using transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS), and stop-flow ab- sorbance disclosing the molecular and supramolecular anatomy of each structure observed. We report a clear evolution from disk micelles to vesicle to high-genus vesicles where each passage is controlled by pH switch or temperature. We show that the process can be rationalised adapting membrane physics theories disclosing important scaling principles that allow the estimation of the vesiculation minimal radius as well as chain entanglement and coupling. This allows us to propose a new approach to generate nanoscale vesicles with genus from 0 to 70 which have been very elusive and difficult to control so far.</p></div></div></div>

Bottom-up Evolution from Disks to High-Genus Polymersomes

2018 ◽  
Author(s):  
Claudia Contini ◽  
Russell Pearson ◽  
Linge Wang ◽  
Lea Messager ◽  
Jens Gaitzsch ◽  
...  
Keyword(s):  
Self Assembly ◽  
The Self ◽  
Amphiphilic Copolymers ◽  
Chain Entanglement ◽  
Bottom Up ◽  
New Approach ◽  
High Genus ◽  
Transmission Electron ◽  
Minimal Radius ◽  
Stop Flow

<div><div><div><p>We report the design of polymersomes using a bottom-up approach where the self-assembly of amphiphilic copolymers poly(2-(methacryloyloxy) ethyl phosphorylcholine)–poly(2-(diisopropylamino) ethyl methacrylate) (PMPC-PDPA) into membranes is tuned using pH and temperature. We study this process in detail using transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS), and stop-flow ab- sorbance disclosing the molecular and supramolecular anatomy of each structure observed. We report a clear evolution from disk micelles to vesicle to high-genus vesicles where each passage is controlled by pH switch or temperature. We show that the process can be rationalised adapting membrane physics theories disclosing important scaling principles that allow the estimation of the vesiculation minimal radius as well as chain entanglement and coupling. This allows us to propose a new approach to generate nanoscale vesicles with genus from 0 to 70 which have been very elusive and difficult to control so far.</p></div></div></div>

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