TY - JOUR

T1 - NMR Studies of Carbosilane Dendrimer with Terminal Mesogenic Groups

AU - Markelov, Denis A.

AU - Matveev, Vladimir V.

AU - Ingman, Petri

AU - Nikolaeva, Marianna N.

AU - Lahderanta, Erkki

AU - Shevelev, Vladimir A.

AU - Boiko, Natalia I.

PY - 2010

Y1 - 2010

N2 - The 4-generation carbosilane dendrimer with terminal cyanobiphenyl mesogenic groups in dilute solution of CDCl3 was investigated using 1H NMR technique. The spectrum was obtained and the relaxation time, T1, was measured in the temperature range 320-225 K. For the first time, the extrema of T1 values were achieved for majority of the dendrimer functional groups. The values of activation energies of the dendrimer functional groups were obtained. The relaxation data for outer and inner methyl groups show that the dendrimer investigated has dense corona and hollow core. This structure is formed because the mesogenic groups do not allow terminal segments to penetrate into the dendrimer, that is, the backfolding effect is absent. The NMR spectral and relaxation data give evidence for changing conformation of the dendrimer internal segments with decreasing temperature. This reorganization is most likely connected with a change of dendrimer size. We suppose that our experimental results will provide additional infor

AB - The 4-generation carbosilane dendrimer with terminal cyanobiphenyl mesogenic groups in dilute solution of CDCl3 was investigated using 1H NMR technique. The spectrum was obtained and the relaxation time, T1, was measured in the temperature range 320-225 K. For the first time, the extrema of T1 values were achieved for majority of the dendrimer functional groups. The values of activation energies of the dendrimer functional groups were obtained. The relaxation data for outer and inner methyl groups show that the dendrimer investigated has dense corona and hollow core. This structure is formed because the mesogenic groups do not allow terminal segments to penetrate into the dendrimer, that is, the backfolding effect is absent. The NMR spectral and relaxation data give evidence for changing conformation of the dendrimer internal segments with decreasing temperature. This reorganization is most likely connected with a change of dendrimer size. We suppose that our experimental results will provide additional infor

KW - carbosilane dendrimer

KW - NMR relaxation

U2 - 10.1021/jp909658v

DO - 10.1021/jp909658v

M3 - Article

VL - 114

JO - Journal of Physical Chemistry B

JF - Journal of Physical Chemistry B

SN - 1520-6106

IS - 12

ER -