scholarly journals Converting non-Mesogenic to Mesogenic Stacking of Amino-s-Triazine-Based Dendrons with p-CN Phenyl Unit by Eliminating Peripheral Dipole

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 185
Author(s):  
Yao-Chih Lu ◽  
Yu-Tsz Hsu ◽  
Tsung-Yen Yang ◽  
I-Chun Liou ◽  
Sheng-Wei Wang ◽  
...  

Three new amino-s-triazine-based dendrons, 1a, 1b, and 1c, containing an aryl-CN moiety in the dendritic skeleton were prepared in 72–81% yields (1a: R1 = − N(n-C8H17)2, R2 = n-OC8H17, 1b: R1 = R2 = − N(n-C8H17)2, 1c: R1 = − N(n-C8H17)2, R2 = − N(n-C4H9)2). Dendrons 1a with N(n-C8H17)2 and n-OC8H17 peripheral substituents, surprisingly, did not show any mesogenic phase during the thermal process. However, non-mesogenic 1a can be converted to mesogenic 1b or 1c by eliminating the peripheral dipole arising from the alkoxy substituent; dendron 1b only comprising the same N(n-C8H17)2 peripheral groups showed a ~25 °C mesogenic range on heating and ~108 °C mesogenic range on cooling. In contrast, dendron 1c possessing different N(n-CmH2m+1)2 (m = 8 versus m = 4) peripheral units, having similar stacking as 1b, exhibited a columnar phase on thermal treatment, but its mesogenic range (~9 and ~66 °C on heating and cooling, respectively) was much narrower than that of 1b, attributed to 1c’s less flexible alkyl chains in the peripheral part of dendron. Dendron 1a with the alkoxy substituent in the peripheral skeleton, creating additional dipole correspondingly, thus, leads to the dendritic molecules having a non-mesogenic stacking. Without the peripheral dipole for intermolecular side-by-side interaction, dendrons 1b and 1c exhibit a columnar phase on thermal treatment because of the vibration from the peripheral alkyl chain.

2012 ◽  
Vol 68 (4) ◽  
pp. o152-o155 ◽  
Author(s):  
Malcolm A. Kelland ◽  
Amber L. Thompson

Tetraisohexylammonium bromide [systematic name: tetrakis(4-methylpentyl)azanium bromide], C24H52N+·Br−, is a powerful structure II clathrate hydrate crystal-growth inhibitor. The crystal structure, in the space groupP3221, contains one ammonium cation and one bromide anion in the asymmetric unit, both on general positions. At 100 K, the ammonium cation exhibits one ordered isohexyl chain and three disordered isohexyl chains. At 250 K, all four isohexyl chains are disordered. In an effort to reduce the disorder in the alkyl chains, the crystal was thermally cycled, but the disorder remained, indicating that it is dynamic in nature.


2020 ◽  
pp. 10-23
Author(s):  
D.V. Novikov

The demand for efficient and qualitative thermal treatment makes certain requirements to the thermal equipment. The thermal equipment, that ideally corresponds to the assigned task of modern production facilities, is vacuum furnaces. The modern production requirements are the boundary conditions for the equipment manufacturers, focusing them on the need for all in one equipment capable of efficient wide production maneuvering, to ensure the possibility of developing and producing new products at minimal cost. As a result of practical research and development, focusing on the world experience and the real need for operation, the Sistem Teknik's article presents vacuum thermal equipment for multiple use – All in one. The equipment is controlled automatically, all parameters are regulated by the process master controller in compliance with the programmed cycle.


2011 ◽  
Vol 474-476 ◽  
pp. 537-542
Author(s):  
Ti Feng Jiao ◽  
Xu Hui Li ◽  
Jing Xin Zhou ◽  
Yuan Yuan Xing ◽  
Jing Ren

Two functional azobenzene derivatives with alkyl chains and different substituted groups have been synthesized and their photoisomerization have also been investigated. It has been found that depending on the alkyl chain and different substituted groups, the formed azobenzene derivatives showed different properties, indicating distinct regulation of molecular skeletons. UV and IR data confirmed commonly the characteristic absorption of alkyl chain and aromatic segments in molecular structures. Thermal analysis demonstrated that the structural influence of both compounds in different temperature ranges. The difference of thermal stability is mainly attributed to the formation of Schiff base group and different substituent groups in molecular structure. The photoisomerization of these compounds both in solution and in cast film can undergo trans-to-cis isomerization by UV light irradiation, depending on different substituted groups. The present results have demonstrated that the special properties of azobenzene derivatives can be effectively turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in functional material field.


2019 ◽  
Vol 7 (45) ◽  
pp. 14198-14204
Author(s):  
Lu Ning ◽  
Guangchao Han ◽  
Yuanping Yi

The impact of the branching positions of alkyl chains on temperature dependent aggregation is rationalized by atomistic molecular dynamics simulations.


RSC Advances ◽  
2015 ◽  
Vol 5 (29) ◽  
pp. 22783-22791 ◽  
Author(s):  
Bo-Yu Chen ◽  
Yun-Chiao Huang ◽  
Jeng-Shiung Jan

Alkyl chain-grafted poly(l-lysine) vesicles with tunable molecular assembly were prepared by varying the polypeptide chain length and grafted alkyl chains.


1975 ◽  
Vol 30 (3) ◽  
pp. 316-322 ◽  
Author(s):  
G. Heppke ◽  
F. Schneider

The effect of temperature and concentration of the added electrolyte tetrabutylammoniumpicrate on the electric conductivity of homologous 4,4′-di-n-alkoxyazoxybenzenes (C1 to C8) in their nematic phase is investigated. In general an increase of the alkyl chain length results in a decrease of the ratio of anisotropy x∥/x⊥. At the lowest temperature of the nematic phase values between 1,6 (C2) and 0,45 (C8) are obtained. This behaviour can be explained by the formation of cybotactic groups with a smectic structure. Increasing the electrolyte concentration reduces the ratio of anisotropy for short alkyl chains, whereas for long chains the ratio rapidly increases.


Author(s):  
MUTSUMI KIMURA ◽  
YUJI YAMAGUCHI ◽  
TOSHIKI KOYAMA ◽  
KENJI HANABUSA ◽  
HIROFUSA SHIRAI

The cationic amphiphilic cobalt(II) phthalocyanines have been prepared, and are characterized by UV-absorption spectra in water and organic solvents and in their mixtures. The monomer–dimer transformation equilibrium was affected by solvent polarity and the length of the alkyl chains in the amphiphilic parts. All complexes are efficient catalysts for the oxidation of 2-mercaptoethanol in the presence of dioxygen. The positive charge around the complex increases the acceleration of the dissociation of 2-mercaptoethanol under neutral pH. The catalytic activity is affected by the length of the alkyl chain; consequently the stability of aggregation between cobalt(II) phthalocyanines, as catalysts for the oxidation of 2-mercaptoethanol, can be changed.


2015 ◽  
Vol 93 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Alexander N. Bourque ◽  
Mary Anne White

Three-component thermochromic mixtures generally consist of a leuco dye, a phenolic colour developer, and a high-melting organic solvent (listed in order of increasing mass). Their colouring behaviour is controlled by competing binary interactions, with the dye–developer interaction responsible for colour formation and the developer–solvent interaction responsible for solid-state colour erasure. In the present study, the reversible thermochromic properties of twelve systems of three-component mixtures comprising crystal violet lactone (CVL, dye), one of four alkyl gallates (developer), and one of three long-chain alkyl alcohols (solvent) were examined, as bulk samples, with slow heating and cooling rates. The thermochromic behaviour (i.e., melt-lightened vs melt-darkened thermochromism) of these mixtures was examined as a function of the difference in length of the alkyl chains attached to the developer and solvent. When the alkyl chain lengths were well-matched, the developer–solvent interaction dominated in the solid state and melt-darkened thermochromism was observed. When the alkyl chain lengths were poorly matched, the dye–developer interaction dominated in the solid state, and melt-lightened thermochromism was observed. Ternary thermochromic phase diagrams define compositional regions of optimal thermochromic behaviour (i.e., demonstrating high colour contrast), showing the intricate balance between developer–dye and developer–solvent interactions, and component concentration, in determining thermochromic behaviour.


2001 ◽  
Vol 709 ◽  
Author(s):  
Seiji Ujiie ◽  
Yumi Yano ◽  
Akira Mori

ABSTRACTA low-molecular-weight liquid crystalline amphiphilic compound (Az6Bu) and a liquid crystalline polymethacrylate [P(Az6Bu)] with amphiphilic-mesogenic side-chains are reported in this present paper. A polyethyleneimine chain with 2-hydroxyethyl side-groups was used as the water-soluble spacer. Az6Bu exhibited a lyotropic columnar phase and no thermotropic mesophase. P(Az6Bu) showed thermotropic and lyotropic liquid crystalline properties. P(Az6Bu) formed thermotropic smectic A and C mesophases on the heating and cooling processes. The lyotropic systems consisting of P(Az6Bu) and water exhibited a smectic C lyomesophase with oilystreak and schlieren textures. The layered structures formed in the thermotropic and lyotropic mesophases are composed of a sublayer produced by the anisotropic alignment of aromatic-mesogenic groups and a sublayer of hydrophilic groups.


2018 ◽  
Vol 6 (7) ◽  
pp. 1899-1907 ◽  
Author(s):  
Zhicheng Pan ◽  
Danxuan Fang ◽  
Yuanqing Song ◽  
Nijia Song ◽  
Mingming Ding ◽  
...  

The alteration of the gemini alkyl chain length could affect the surface charge exposure, stability, and the protein absorption properties of nanocarriers.


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