921229-75-6Relevant academic research and scientific papers
Transfer, amplification, and inversion of helical chirality mediated by concerted interactions of C3-supramolecular dendrimers
Peterca, Mihai,Imam, Mohammad R.,Ahn, Cheol-Hee,Balagurusamy, Venkatachalapathy S. K.,Wilson, Daniela A.,Rosen, Brad M.,Percec, Virgil
supporting information; experimental part, p. 2311 - 2328 (2011/04/23)
The synthesis, structural, and retrostructural analysis of two libraries containing 16 first and second generation C3-symmetric self-assembling dendrimers based on dendrons connected at their apex via trisesters and trisamides of 1,3,5-benzenetricarboxylic acid is reported. A combination of X-ray diffraction and CD/UV analysis methods demonstrated that their C3-symmetry modulates different degrees of packing on the periphery of supramolecular structures that are responsible for the formation of chiral helical supramolecular columns and spheres self-organizable in a diversity of three-dimensional (3D) columnar, tetragonal, and cubic lattices. Two of these periodic arrays, a 3D columnar hexagonal superlattice and a 3D columnar simple orthorhombic chiral lattice with P2221 symmetry, are unprecedented for supramolecular dendrimers. A thermal-reversible inversion of chirality was discovered in helical supramolecular columns. This inversion is induced, on heating, by the change in symmetry from a 3D columnar simple orthorhombic chiral lattice to a 3D columnar hexagonal array and, on cooling, by the change in symmetry from a 2D hexagonal to a 2D centered rectangular lattice, both exhibiting intracolumnar order. A first-order transition from coupled columns with long helical pitch, to weakly or uncorrelated columns with short helical pitch that generates a molecular rotator, was also discovered. The torsion angles of the molecular rotator are proportional to the change in temperature, and this effect is amplified in the case of the C 3-symmetric trisamide supramolecular dendrimers forming H-bonds along their column. The structural changes reported here can be used to design complex functions based on helical supramolecular dendrimers with different degree of packing on their periphery.
The first examples of optically active tris(N-salicylideneaniline)s: Manifestation of chirality from molecules to fluid columnar phases
Yelamaggad, Channabasaveshwar V.,Achalkumar, Ammathnadu S.,Rao, Doddamane S. Shankar,Prasad, Subbarao Krishna
, p. 4521 - 4529 (2008/12/22)
Tris(N-salicylideneaniline)s comprising chiral tails in varying numbers self-organize into a room temperature helical columnar mesophase resulting from the chiral stacking of the constituent molecules differing in their rotational symmetry and ratio as ev
Steric communication of chiral information observed in dendronized polyacetylenes
Percec, Virgil,Aqad, Emad,Peterca, Mihai,Rudick, Jonathan G.,Lemon, Lance,Ronda, Juan C.,De, Binod B.,Heiney, Paul A.,Meijer
, p. 16365 - 16372 (2007/10/03)
Structural and retrostructural analysis of helical dendronized polyacetylenes (i.e., self-organizable polyacetylenes containing first generation dendrons or minidendrons as side groups) synthesized by the polymerization of minidendritic acetylenes with [R
