- Photoresponsive behavior of hydrophilic/hydrophobic-based novel azobenzene mesogens: Synthesis, characterization and their application in optical storage devices
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Three series of alkoxy chain-bearing azobenzene-derived quaternary ammonium iodides with an alkoxy chain at one end, namely N,N-diethanol-6-(4-((4′-alkyloxyphenyl)diazenyl)phenoxy)hexan-1-ammonium iodides, N-ethyl-N-ethanol-6-(4-((4′-alkyloxyphenyl)diazenyl)phenoxy)hexan-1-ammonium iodides and N,N-diethyl-6-(4-((4′-alkyloxyphenyl)diazenyl)phenoxy)hexan-1-ammonium iodides were synthesized and characterized. Their mesomorphic and photoswitching properties were examined via polarising optical microscopy (POM), differential scanning calorimetry (DSC) and UV-vis spectrophotometry. The liquid crystalline tilted schlieren texture of smectic C, non-tilted natural focal conic texture of smectic A and smectic B phases were observed in the N,N-diethanol- and N-ethyl-N-ethanol-bearing ammonium group substituted at the terminal via the alkoxy chain of the azo moiety. In these azo moieties, the equilibrium time for trans-cis isomerization was about 1 min and cis-trans isomerization occurred at around 590 min, which had the highest alkoxy chain and no hydroxyl group on their head group. The absence of a hydroxyl group on the terminal head group resulted in slow thermal back relaxation, whereas the hydroxyl group-bearing head group showed fast thermal back relaxation. These results suggest that the influence of the substituent on the cationic ammonium head group and alkoxy chain length on the photoisomerization of the azo compounds is vital for optical storage devices. Furthermore, the device fabricated using these materials demonstrated that they are excellent candidates for optical image storage applications.
- Sunil,Yam, Wan Sinn,Hegde, Gurumurthy
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p. 40588 - 40606
(2019/12/25)
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- Aminofluorene-Mediated Biomimetic Domino Amination-Oxygenation of Aldehydes to Amides
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A conceptually novel biomimetic strategy based on a domino amination-oxygenation reaction was developed for direct amidation of aldehydes under metal-free conditions employing molecular oxygen as the oxidant. 9-Aminofluorene derivatives acted as pyridoxamine-5′-phosphate equivalents for efficient, chemoselective, and operationally simple amine-transfer oxygenation reaction. Unprecedented RNH transfer involving secondary amine to produce secondary amides was achieved. In the presence of 18O2, 18O-amide was formed with excellent (95%) isotopic purity.
- Ghosh, Santanu,Jana, Chandan K.
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supporting information
p. 5788 - 5791
(2016/11/29)
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- Utilization of evaporation during the crystallization process: Self-templation of organic parallelogrammatic pipes
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Analogues of 4-dodecyloxy-2-trifluoromethylbenzamide (12FH2) consisting of a hydrophobic alkyl chain, a trifluoromethylated aromatic ring, and a self-complementary hydrogenbonding amido group were synthesized, and the structural effect of each component o
- Seo, Myungeun,Kim, Jung Hak,Seo, Gon,Shin, Chae-Ho,Kim, Sang Youl
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experimental part
p. 612 - 622
(2009/06/20)
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- Highly symmetric 2D rhombic nanoporous networks arising from low symmetry amphiphiles
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(Figure Presented) Highly symmetric 2D nanoporous molecular networks containing rhombic voids are demonstrated to be accessible from low symmetry amphiphilic molecules. The amide amphiphiles overcome the barrier to symmetry generation in the two-dimensional crystal through forming an aggregate as a building block. This aggregate consists of three inequivalent amphiphiles that assemble to create 3- and 6-fold rotation axes through hydrogen bonding. In the 6-fold rotation axis, an unusual hydrogen bonding network, supported by high resolution scanning tunneling microscopy(STM) images and computation, is observed. This network formed by amide groups significantly contributes to constructing the rhombic nanoporous network, whereas carboxylic acid amphiphiles do not adopt this nanoporo us network due to a geometric difference of hydrogen bonding. This investigation demonstrates that a high symmetry pattern is achievable withoutcorrelation with molecular symmetry through the proper combination of n oncovalent interactions of simple amphiphilic molecules.
- Ahn, Seokhoon,Morrison, Christine N.,Matzger, Adam J.
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supporting information; experimental part
p. 7946 - 7947
(2009/12/02)
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- Naphthyridine-based helical foldamers and macrocycles: Synthesis, cation binding, and supramolecular assemblies
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(Figure Presented) Unraveling the factors that control the conformation of molecular chains is of great interest both for understanding the shape of biological molecular strands and for designing artificial ones that adopt desired forms. Thus, a variety of artificial folding codons have been identified that enforce the formation, among others, of helices, strands, and loops, the major emphasis being on the shape of the foldamer. We report herein the synthesis and study of a family of foldamers and macrocycles based on the 1,8-naphthyridine and pyrimidine units, whose internal cavity is large enough to accommodate ionic substrates, and focus on the impact of guest binding within a cylindrical environment. Interestingly, the binding event within these large oligomers is translated to the outside of the receptors and affects the interaction of the overall complexes with the outside world. For instance, alkali cations bind to the one-turn helices and macrocycles to promote fibril formation and aggregation. Also, polyammonium substrates are able to tune the length of the overall helix assemblies and the rigidity of long oligomers. The reported data on one-turn, two-turn helices and macrocycles not only allows one to devise a model for the ion-controlled supramolecular assembly of such systems but also provides evidence that such controlled scaffolds bear promise in the design of complex systems.
- Petitjean, Anne,Cuccia, Louis A.,Schmutz, Marc,Lehn, Jean-Marie
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p. 2481 - 2495
(2008/09/19)
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