Tris(o-phenylenedioxy)cyclotriphosphazene: the clathration-induced monoclinic to hexagonal solid-state transition

Arrays of Dipolar Molecular Rotors in Tris(o-phenylenedioxy)cyclotriphosphazene

“…Inclusion compounds of TPP with numerous small molecules such as alkanes or benzene have a venerable history in host-guest chemistry [49][50][51][52][53][54][55][56][57][58]. A monoclinic modification of TPP [50,53] that does not form inclusion compounds is also known and below~150 C it is actually more stable than the empty hexagonal form. However, it is less stable than the hexagonal form, up to at least 350 C, if the latter is filled with a nonvolatile guest [52].…”

“…Besides differentiating between monoclinic and hexagonal TPP, solid-state NMR is also able to determine which parts of a proton-containing guest molecule are inserted into TPP channels and which parts remain outside, because the chemical shifts of NMR-active atoms are exquisitely sensitive to their environment. The ring currents produced by the benzene rings in TPP are known to modify chemical shifts by several ppm, thus allowing the inclusion to be easily recognized Reproduced with permission from [43] 180 K. Zhao et al [50][51][52][53][54][55][56][57]. For a detailed analysis it is necessary to first secure a full assignment for all NMR-active nuclei of the guest rotor molecule from a study of its solution or solid NMR spectrum.…”

Supramolecular Structures of Cyclotriphosphazenes

“…Two phenylene paddles are bent backward, enabling two molecules to pair up via their opened sides (see also Fig. 2) [9]. However, upon exposure to guest molecules the monoclinic crystal disintegrates and the hexagonal clathrate structure is regained.…”

Preparation and Characterization of Inclusion Compounds Using TEMPOL and an Organic 1-D Nanochannel as a Template

“…Its pore diameter is adjustable from 0.46 (for guest-free TPP) to 1 nm depending on the guest size. The TPP nanochannel has been of interest as it can accommodate various guest molecules [1][2][3][4][5][6]. The basic structure of the TPP nanochannel is based on the hexagonal phase of TPP: its space group P6 3 =m, a ¼ b ¼ 1.1454, c ¼ 1.016 nm, Z ¼ 2 [3].…”