Liquid−Crystalline Janus-Type Fullerodendrimers Displaying Tunable Smectic−Columnar Mesomorphism

Abstract

Janus-type liquid-crystalline fullerodendrimers were synthesized via the 1,3-dipolar cycloaddtition of two mesomorphic dendrons and C60. By assembling poly(aryl ester) dendrons functionalized with cyanobiphenyl groups, displaying lamellar mesomorphism, with poly(benzyl ether) dendrons carrying alkyl chains, which display columnar mesomorphism, we could tailor by design the liquid-crystalline properties of the title compounds as a function of each dendron size. The liquid-crystalline properties were examined by polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. Depending on the dendrimer generations, smectic (SmC and/or SmA phases) or columnar (Colr-c2mm or Colr-p2gg phases) mesomorphism was obtained. The supramolecular organization is governed by (1) the adequacy of the cross-sectional area of the dendrons, (2) the microsegregation of the dendrimer, (3) the deformation of the dendritic core, and (4) the dipolar interactions between the cyanobiphenyl groups. Comparison of the mesomorphic properties of two fullerodendrimers with those of model compounds (fullerene-free analogues) indicated that the C60 unit does not influence the type of mesophase that is formed. Molecular properties determined in solution (permanent dipole moment, specific dielectric polarization, molar Kerr constant) confirm that microsegregation persists in solution and strengthen the models proposed for the structure of the mesophases.

Arrays of giant octagonal and square cylinders by liquid crystalline self-assembly of X-shaped polyphilic molecules

“…To each of its ends, a glycerol groups (A) was attached, capable of forming a cooperative and dynamic hydrogen-bonding network. Hence, these compounds represent Janus-type [27][28][29][30][31][32][33] X-shaped quaternary amphiphiles. An equivalent series of compounds 2 was also synthesized, having a shorter C 10 F 21 segment instead of the C 12 F 25 segment.…”

Mesomorphic Poly(aryl ester)/Poly(benzyl ether) Dendrimers/co-Dendrimers with C60as the Core

“…Due to their stiffness, the molecules' packing in the mesophase of compound 2 will differ from the process of compounds 1, having relatively free and mobile sub-units. Molecular stiffness is responsible also for the specific segregation of sub-units detected by X-rays diffraction in the mesophase of compound 2 [10].…”

“…1a, compound 2). FIGURE 1 Chemical structure of fullerene-containing poly(aryl ester) dendrimer 1, poly(aryl ester)=poly(benzyl ether) co-dendrimer 2 with the data on their phase transition temperatures [5,10]; R is mesogenic end-group (a); and chemical structure of compounds D1 (the second generation) and D2 (the third generation) analogues to dendrons of 1 and 2 (b).…”

“…The influence of the dendrons' generation number and the number of mesogenic groups on the mesomorphic behavior of fullerene-containing poly(aryl ester)=poly(benzyl ether) dendrimers=co-dendrimers have been studied earlier [5,9,10]. Because the previous studies have been performed for methanofullerene-and fulleropyrroline-derivatives' series separately, the influence of chemical linkage type between fullerene C 60 and polyester=polyether dendrons on mesomorphic ordering of fullerene-containing dedritic structure compounds has been out of discussions and has not been yet analyzed.…”

Synthesis of first generation Janus-Type dendrimers bearing Asp oligopeptides and naproxen

“…7 The synthesis of part of these compounds have already been described, often using them for self-assembly or as liquid crystals. [8][9][10] Frechet et. al.…”