Synthesis and Helical Structure of Poly(N-butynylamide)s Having Various Side Chains, Where the Helix Is Highly Affected by the Methyl Branch and the Lactone Moiety

2008 ◽  
Vol 41 (4) ◽  
pp. 1086-1093 ◽  
Author(s):  
Yuji Suzuki ◽  
Junichi Tabei ◽  
Masashi Shiotsuki ◽  
Yoshihito Inai ◽  
Fumio Sanda ◽  
...  
Keyword(s):  
Helical Structure ◽  
Side Chains ◽  
Methyl Branch

scholarly journals Highly efficient stabilisation of meta-ethynylpyridine polymers with amide side chains in water by coordination of rare-earth metals

2015 ◽  
Vol 13 (6) ◽  
pp. 1700-1707 ◽  
Author(s):  
Hiroki Makida ◽  
Hajime Abe ◽  
Masahiko Inouye
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Rare Earth Metals ◽  
Earth Metal ◽  
Helical Structure ◽  
Metal Salts ◽  
Side Chains ◽  
Highly Efficient

An amphiphilic meta-ethynylpyridine polymer with chiral amide side chains coordinated with rare-earth metal salts, especially strongly with Sc(iii), to stabilise its helical structure with CD enhancement.

Mesophase and Optical Properties of Side Chain Copolyacrylate with Mesogens and OLLA Segments Side Chains

2011 ◽  
Vol 181-182 ◽  
pp. 397-400
Author(s):  
Ya Ping Liu ◽  
Zhuo Hua Li ◽  
Ling Min Sun ◽  
Run Tao Dong ◽  
Hong Ru Chen ◽  
...  
Keyword(s):  
Ring Opening ◽  
Optical Rotation ◽  
Helical Structure ◽  
Ring Opening Polymerization ◽  
Side Chain ◽  
Side Chains ◽  
Induce Effect ◽  
Phase Structures ◽  
Acrylate Esters ◽  
Phase Behaviors

Thermal properties and phase behaviors of series of newly synthesized copolyacrylate esters with oligomeric-L-LA (OLLA) segments (DP = 10-40) and mesogens as side chains were characterized. The OLLAs prepared by ring opening polymerization of L-LA with active HO-group were modified to form polymerizable acrylate esters and then copolymerized with polymerizable mesogens. The thermal behaviors of these copolyacrylate esters were studied by DSC and POM measurements and phase structures by XRD measurements. The mesogens showed very good induce effect on the formation of layered structures. CD measurements were used to determine the helical structure and the optical rotation power of the side chain copolyacrylate esters.

Complexation of poly(Lys-Ala) and poly(Lys-Ala-Ala-Ala) with pectins and potassium oligogalacturonates

1988 ◽  
Vol 53 (11) ◽  
pp. 2833-2842 ◽  
Author(s):  
Slavomír Bystrický ◽  
Anna Malovíková ◽  
Tibor Sticzay ◽  
Karel Bláha
Keyword(s):  
Charge Density ◽  
Helical Structure ◽  
Local Mode ◽  
Side Chains ◽  
Specific Band ◽  
Esterification Degree ◽  
Superhelical Structure ◽  
Circular Dichroic

The selected model polypeptides poly(Lys-Ala) and poly(Lys-Ala-Ala-Ala) underwent a helix-forming interaction with potassium pectates and pectinates of various esterification degree (E) and with some potassium oligogalacturonates (n = 2-5, 9, 13). Formation of the complex quantitatively monitored by a circular dichroic measurement showed that the specific band distribution of charged side chains of lysine units at the surface of helical structure does not constitute grounds for the local mode of interaction. Potassium pectinate of esterification degree E 57%, corresponding to polypeptides by charge density, does not reveal enhanced complexation values. The complex-forming efficacy continuously decreases with the increase of the esterification degree of pectin. Saturation of charges of the polypeptide was achieved predominantly by the spatial action of the superhelical structure of D-galacturonate chains.

Hydrogen—Deuterium Exchange in Bovine Serum Albumin Protein Monitored by Fourier Transform Infrared Spectroscopy, Part I: Structural Studies

2005 ◽  
Vol 59 (11) ◽  
pp. 1347-1356 ◽  
Author(s):  
Jože Grdadolnik ◽  
Yves Maréchal
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Structural Changes ◽  
Helical Structure ◽  
Correlation Spectroscopy ◽  
Side Chains ◽  
Hydrogen Atoms ◽  
Oh Groups ◽  
Higher Temperature

The structure of the amide I band of bovine serum albumin (BSA) was determined using an H/D exchange experiment. The difference between the dry and hydrated exchange spectrum revealed the fine structure of the amide I band. The band at 1717 ± 2 cm−1 is due to the vibration of the COOH moieties from the protein side chains. Band components at 1682 ± 2 cm−1, 1655 ± 2 cm−1, and 1637 ± 2 cm−1 are assigned to the vibrations of the backbone C=O. These three bands belong to vibrations of three different populations of amide groups differing in the number of established H-bonds. The connectivity between the frequencies of various amide vibrations was determined by two-dimensional generalized correlation spectroscopy and spectral decomposition. About 7% of the whole exchangeable hydrogen atom population (NH, NH2, and OH groups from backbone and side chains) remains unexchanged, and these hydrogen atoms belong mainly to the NH groups, which are H-bonded to specific C=O groups. Moreover, this study concerns the approximately 10% of hydrogen atoms belonging to a particular HN … OC population with a characteristic amide A frequency at 3290 cm−1 and an amide I band at 1655 ± 2 cm−1, usually attributed to the α-helical structure that remains unexchanged. At higher temperature the exchange is more efficient. Upon heating, a further 4% of these NH groups are deuterated. The comparison of the exchange spectrum at higher temperature with the structural changes of the protein at the same temperature implies that the change in overall dynamics of the protein improve the level of exchange.

scholarly journals PHOTO-INDUCED FORMATION OF α-HELICAL STRUCTURE OF POLY(L-GLUTAMIC ACID) CONTAINING PARAROSEANILINE IN THE SIDE CHAINS

1986 ◽  
Vol 42 (2) ◽  
pp. T107-T110
Author(s):  
Morimasa Sato ◽  
Takatoshi Kinoshita ◽  
Akira Takizawa ◽  
Yoshiharu Tsujita
Keyword(s):  
Glutamic Acid ◽  
Helical Structure ◽  
Side Chains

Synthesis and Helical Structure of Poly(1-methylpropargyl ester)s with Various Side Chains

2008 ◽  
Vol 3 (12) ◽  
pp. 2075-2081 ◽  
Author(s):  
Yuji Suzuki ◽  
Masashi Shiotsuki ◽  
Fumio Sanda ◽  
Toshio Masuda
Keyword(s):  
Helical Structure ◽  
Side Chains

Single molecule optical diffraction: A tool for understanding the structure of triple stranded left-hand helical cellulose

1989 ◽  
Vol 47 ◽  
pp. 1024-1025
Author(s):  
George C. Ruben ◽  
William Krakow
Keyword(s):  
Single Molecule ◽  
Helical Structure ◽  
Optical Diffraction ◽  
Maximum Diameter ◽  
Primary Cell Wall ◽  
Cellulose Synthesis ◽  
Left Hand ◽  
Left Handed ◽  
Freeze Dried ◽  
Diffraction Patterns

Tobacco primary cell wall and normal bacterial Acetobacter xylinum cellulose formation produced a 36.8±3Å triple-stranded left-hand helical microfibril in freeze-dried Pt-C replicas and in negatively stained preparations for TEM. As three submicrofibril strands exit the wall of Axylinum , they twist together to form a left-hand helical microfibril. This process is driven by the left-hand helical structure of the submicrofibril and by cellulose synthesis. That is, as the submicrofibril is elongating at the wall, it is also being left-hand twisted and twisted together with two other submicrofibrils. The submicrofibril appears to have the dimensions of a nine (l-4)-ß-D-glucan parallel chain crystalline unit whose long, 23Å, and short, 19Å, diagonals form major and minor left-handed axial surface ridges every 36Å.The computer generated optical diffraction of this model and its corresponding image have been compared. The submicrofibril model was used to construct a microfibril model. This model and corresponding microfibril images have also been optically diffracted and comparedIn this paper we compare two less complex microfibril models. The first model (Fig. 1a) is constructed with cylindrical submicrofibrils. The second model (Fig. 2a) is also constructed with three submicrofibrils but with a single 23 Å diagonal, projecting from a rounded cross section and left-hand helically twisted, with a 36Å repeat, similar to the original model (45°±10° crossover angle). The submicrofibrils cross the microfibril axis at roughly a 45°±10° angle, the same crossover angle observed in microflbril TEM images. These models were constructed so that the maximum diameter of the submicrofibrils was 23Å and the overall microfibril diameters were similar to Pt-C coated image diameters of ∼50Å and not the actual diameter of 36.5Å. The methods for computing optical diffraction patterns have been published before.

Influence of Flexible Side-Chains on the Breathing Phase Transition of Pillared Layer MOFs: A Force Field Investigation

2020 ◽  
Author(s):  
Julian Keupp ◽  
Johannes P. Dürholt ◽  
Rochus Schmid
Keyword(s):  
First Principles ◽  
Good Accuracy ◽  
Field Investigation ◽  
Square Lattice ◽  
Side Chain ◽  
Second Step ◽  
Side Chains ◽  
Dynamics Simulations ◽  
Complex Phenomena ◽  
Closed Pore

The prototypical pillared layer MOFs, formed by a square lattice of paddle-<br>wheel units and connected by dinitrogen pillars, can undergo a breathing phase<br>transition by a “wine-rack” type motion of the square lattice. We studied this not<br>yet fully understood behavior using an accurate first principles parameterized force<br>field (MOF-FF) for larger nanocrystallites on the example of Zn 2 (bdc) 2 (dabco) [bdc:<br>benzenedicarboxylate, dabco: (1,4-diazabicyclo[2.2.2]octane)] and found clear indi-<br>cations for an interface between a closed and an open pore phase traveling through<br>the system during the phase transformation [Adv. Theory Simul. 2019, 2, 11]. In<br>conventional simulations in small supercells this mechanism is prevented by periodic<br>boundary conditions (PBC), enforcing a synchronous transformation of the entire<br>crystal. Here, we extend this investigation to pillared layer MOFs with flexible<br>side-chains, attached to the linker. Such functionalized (fu-)MOFs are experimen-<br>tally known to have different properties with the side-chains acting as fixed guest<br>molecules. First, in order to extend the parameterization for such flexible groups,<br>1a new parametrization strategy for MOF-FF had to be developed, using a multi-<br>structure force based fit method. The resulting parametrization for a library of<br>fu-MOFs is then validated with respect to a set of reference systems and shows very<br>good accuracy. In the second step, a series of fu-MOFs with increasing side-chain<br>length is studied with respect to the influence of the side-chains on the breathing<br>behavior. For small supercells in PBC a systematic trend of the closed pore volume<br>with the chain length is observed. However, for a nanocrystallite model a distinct<br>interface between a closed and an open pore phase is visible only for the short chain<br>length, whereas for longer chains the interface broadens and a nearly concerted trans-<br>formation is observed. Only by molecular dynamics simulations using accurate force<br>fields such complex phenomena can be studied on a molecular level.

Liquid Crystal Trimers Incorporating Saturated Isosteres of Benzene and Exhibiting Modulated Nematic Phases

2019 ◽  
Author(s):  
Adam Al-Janabi ◽  
Richard Mandle
Keyword(s):  
Liquid Crystal ◽  
Helical Structure ◽  
Molecular Shape ◽  
Saturated Hydrocarbons ◽  
Fluid System ◽  
Structural Requirement ◽  
Disubstituted Benzene ◽  
Bona Fide ◽  
Nematic Phases ◽  
Bend Angles

<p>The nematic twist-bend (N<sub>TB</sub>) liquid crystal phase possesses a local helical structure with a pitch length of a few nanometres and is the first example of spontaneous symmetry breaking in a fluid system. All known examples of the N­<sub>TB­</sub> phase occur in materials whose constituent mesogenic units are aromatic hydrocarbons. It is not clear if this is due to synthetic convenience or a <i>bona fide</i> structural requirement for a material to exhibit this phase of matter. In this work we demonstrate that materials consisting largely of saturated hydrocarbons could also give rise to this mesophase. Furthermore, replacement of 1,4-disubstituted benzene with <i>trans</i> 1,4-cyclohexane or even 1,4-cubane does not especially alter the transition temperatures of the resulting material nor does it appear to impact upon the heliconical tilt angle, suggesting the local structure of the phase is unperturbed. Calculating the probability distribution of bend angles reveals that the choice of isosteric group has little impact on the overall molecular shape, demonstrating the shape-driven nature of the N<sub>TB</sub> phase. </p>

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