betadex and alpha-bromonaphthalene

Development of self-healing and photostimulated luminescent supramolecular polymeric materials is important for artificial soft materials. A supramolecular polymeric hydrogel is reported based on the host-guest recognition between a β-cyclodextrin (β-CD) host polymer (poly-β-CD) and an α-bromonaphthalene (α-BrNp) polymer (poly-BrNp) without any additional gelator, which can self-heal within only about one minute under ambient atmosphere without any additive. This supramolecular polymer system can be excited to engender room-temperature phosphorescence (RTP) signals based on the fact that the inclusion of β-CD macrocycle with α-BrNp moiety is able to induce RTP emission (CD-RTP). The RTP signal can be adjusted reversibly by competitive complexation of β-CD with azobenzene moiety under specific irradiation by introducing another azobenzene guest polymer (poly-Azo).

Topics: beta-Cyclodextrins; Fluorescence; Hydrogels; Macromolecular Substances; Molecular Structure; Naphthalenes; Photochemical Processes; Polymers; Temperature

Fluorescence and room temperature phosphoresce (CD-RTP) induced by cyclodextrin methods were employed to investigate the effects of steric hindrance of guest molecule on the formation of inclusion complexes of beta-cylcodextrin (beta-CD) and bromonaphthalene (BrN). It has been found that the RTP intensity of 2-BrN/beta-CD/n-Bu/ph was less than one third of that of 1-BrN/beta-CD/n-Bu/ph and fluorescence emission spectra of 2-BrN/beta-CD/n-Bu/ph had a red shift of 5-10 nm comparing with that of 1-BrN/beta-CD/n-Bu/ph under the optimum experimental conditions, respectively. These results exhibited that the steric locations of bromine in BrN strongly influenced the formation of inclusion complexes. The determination of the two quadri-inclusion complexes constants further demonstrated that the steric hindrance has a great effect on the formation of inclusion complexes. According to the above experimental results, the mechanism of formation of inclusion complexes were discussed briefly.

Topics: beta-Cyclodextrins; Hydrogen-Ion Concentration; Kinetics; Luminescence; Luminescent Measurements; Models, Chemical; Molecular Structure; Naphthalenes; Spectrometry, Fluorescence; Temperature

Room-temperature phosphorescence of 1-BrN induced by a combination of OPE-10 and Triton X-100 with beta-CD was comparatively studied. In terms of molecular size and dimensions of beta-CD, the octyl group and phenyl group of OPE-10 and Triton X-100 were incorporated into the cavity of beta-CD and the complexes with the stoichiometry of 1:1 were formed. The removal of water molecules inside the cavity results in a greater apolar interior. By enhanced hydrophobic interaction, the cavity occupied by OPE-10 and Triton X-100 is able to further capture another 1-BrN and form close packing 1:1:1 ternary inclusion complexes with apparent stability constant of 1.09 x 10(5) and 4.47 x 10(5) L2 x mol(-2), respectively. 1-BrN shows bright phosphorescence at room temperature due to the greater rigidity in the limited space and the favorable microenvironment shielding from external quenchers and quenching effect on the fluorescence of the phenyl group of OPE-10 and Triton X-100 within the same cavity. In the case of Triton X-100, the larger tert-octyl group better shields off external quenchers such as dissolved oxygen and iodide ion. Energy transfer from the excited phenyl group of Triton X-100 to adjacent 1-BrN acceptor was observed.

Topics: beta-Cyclodextrins; Drug Synergism; Luminescent Measurements; Naphthalenes; Surface-Active Agents; Temperature