- The Cooperative Effect of Both Molecular and Supramolecular Chirality on Cell Adhesion
-
Although helical nanofibrous structures have great influence on cell adhesion, the role played by chiral molecules in these structures on cells behavior has usually been ignored. The chirality of helical nanofibers is inverted by the odd–even effect of methylene units from homochiral l-phenylalanine derivative during assembly. An increase in cell adhesion on left-handed nanofibers and weak influence of cell behaviors on right-handed nanofibers are observed, even though both were derived from l-phenylalanine derivatives. Weak and negative influences on cell behavior was also observed for left- and right-handed nanofibers derived from d-phenylalanine, respectively. The effect on cell adhesion of single chiral molecules and helical nanofibers may be mutually offset.
- Liu, Jinying,Yuan, Feng,Ma, Xiaoyu,Auphedeous, Dang-i Y.,Zhao, Changli,Liu, Chuntai,Shen, Changyu,Feng, Chuanliang
-
p. 6475 - 6479
(2018/05/08)
-
- Fabrication of nanocrystals from diolefin derivatives and their solid-state photoreaction behavior
-
Nanocrystals of seven p-phenylenediacrylates, i.e., dimethyl (la), didecyl (lb), diundecyl (1c), ditetradecyl (1d), dipentadecyl (1e), dioctadecyl (1f), and dicholesteroyl (1g) derivatives, and 2,5-distyrylpyrazine (2) were fabricated by the reprecipitation method and their photochemical reaction behaviors were investigated in comparison to those of bulk crystals. The bulk crystals of 1a- 1c and 2 were found to be photoreactive, whereas those of 1d-1g were less photoreactive. In contrast, all of the nanocrystals of 1a-1g and 2 showed high photoreactivity. Nanocrystals of la and 2 were demonstrated to have the same packing as the corresponding polymerizable bulk crystals, and they gave the corresponding polymers by photoirradiation. The polymer crystal structures in their nanocrystals were confirmed to be the same as those in bulk crystals by X-ray and electron diffraction analyses. Their single-crystal-to-single-crystal transformation was established by their nanocrystallization. On the other hand, other nanocrystals (1b-1g) were found to have different packings compared with the corresponding bulk crystals. After photoirradiation, their crystallinity was degraded to form amorphous products.
- Miura, Hirohiko,Takahashi, Shu,Kasai, Hitoshi,Okada, Shuji,Yase, Kiyoshi,Oikawa, Hidetoshi,Nakanishi, Hachiro
-
experimental part
p. 510 - 517
(2011/10/09)
-
- Cyclization of propargylic amides: Mild access to oxazole derivatives
-
The substrate scope, the mechanistic aspects of the gold-catalyzed oxazole synthesis, and substrates with different aliphatic, aromatic, and functional groups in the side chain were investigated. Even molecules with several propargyl amide groups could easily be converted, delivering di- and trioxazoles with interesting optical properties. Furthermore, the scope of the gold(I)-catalyzed alkylidene synthesis was investigated. Further functionalizations of these isolable intermediates of the oxazole synthesis were developed and chelate ligands can be obtained. The use of Barluenga's reagent offers a new and mild access to the synthetically valuable iodoalkylideneoxazoles from propargylic amides, this reagent being superior to other sources of halogens.
- Weyrauch, Jan P.,Hashmi, A. Stephen K.,Schuster, Andreas,Hengst, Tobias,Schetter, Stefanie,Littmann, Anna,Rudolph, Matthias,Hamzic, Melissa,Visus, Jorge,Rominger, Frank,Frey, Wolfgang,Bats, Jan W.
-
supporting information; experimental part
p. 956 - 963
(2010/06/12)
-
- Synthesis and Properties of 4,4,9,9-Tetramethylparacyclophane-5,6,7,8-tetrone
-
The synthesis of 4,4,9,9-tetramethylparacyclophane-5,6,7,8-tetrone (26) has been achieved in a multistep procedure.Compound 26 is the first cyclic tetraketone whose structure has been studied by X-ray analysis.The key intermediates were 4,4,9,9-tetramethylparacyclophane-6,7-dione (22), 6,7-bis-4,4,9,9-tetramethylparacyclophane-5,7-diene (24), and two epimeric 5,8-dihydroxy-4,4,9,9-tetramethylparacyclophane-6,7-diones 25a and 25b.X-ray analyses have been performed on 24, 25b and 26.That on 24 reveals a dihedral angle of 57 deg between the two silyenol ether groups.The product analyses and the configurations of 25a and 25b together with the isolation of the bis(epoxide) intermediate 28 allow conclusions to be drawn on the oxidation mechanism of 24 with m-CPBA (Rubottom reaction).The stability of 26 is ascribed to steric factors.
- Gleiter, Rolf,Kraemer, Rolf,Irngartinger, Hermann,Bissinger, Claus
-
p. 252 - 258
(2007/10/02)
-