Xin-Zhen Du

A study of the properties of the 1:1 inclusion complex of beta-cyclodextrin with cetyltrimethylammonium bromide

Abstract The properties of the 1:1 inclusion complex of β-cyclodextrin (β-CD) with cetyltrimethylammonium bromide (CTAB) were investigated by pyrene and 1-pyrene butyric acid fluorescence. It is shown that in the 1:1 CTAB/β-CD inclusion complex the hydrophobic alkyl chain is included in the β-CD cavity, with the majority of the chain protruding into the bulk phase with the counterion binding to the polar head. In aqueous solution this 1:1 CTAB/β-CD inclusion complex aggregates and micellizes into micelles of which the interior hydrophobic region (the Stern layer and micelle core) is less polar than that of CTAB and its critical micelle concentration is 2.05 × 10 −3 mol l −1 , which is in agreement with the value determined by surface tension.

Intense room-temperature phosphorescence of 1-bromonaphthalene in organized media of beta-cyclodextrin and triton X-100

In aerated aqueous solution, intense room-temperature phosphorescence (RTP) of 1-bromonaphthalene (1-BrN) is observed with an host–guest inclusion complex composed of Triton X-100, 1-BrN, and beta-cyclodextrin (β-CD). Triton X-100 is incorporated into the hydrophobic cavity of β-CD as the second guest molecule, and a 1:1:1 ternary complex is formed. This complex, with a polar head group, can be well distributed in aqueous solution, and stable RTP is obtained. Ethanol further enhances the RTP of the ternary complex, whereas 1-propanol and 1-butanol greatly attenuate RTP. Spectral analyses indicate that 1-BrN in the β-CD cavity is replaced by 1-propanol and 1-butanol.

Study of room-temperature phosphorescence of 1-bromonaphthalene in sodium dodecylbenzene sulfonate and beta-cyclodextrin solution

Abstract Intense room-temperature phosphorescence (RTP) of 1-bromo-naphthalene (1-BrN) was studied in aerated aqueous solutions containing sodium dodecylbenzene sulfonate (SDBS) and β-cyclodextrin (β-CD). It has been found that considerably enhanced RTP arises from the formation of the 1:1:1/SDBS:1-BrN:β-CD ternary inclusion complex in premicellar solutions. The spectral and structural analyses of molecules indicate that the phenyl ring of SDBS is included in the apolar cavity of β-CD and the polar head group and a part of hydrocarbon chain located outside the cavity. Surface tension of the solutions demonstrates that the presence of micelles results in serious phosphorescence quenching.

Phosphorescence study of 1-bromonaphthalene in aerated aqueous solution of surfactant and β-cyclodextrin

Abstract Surfactant (S) induced room-temperature phosphorescence (RTP) from 1-bromonaphthalene (1-BrN) in aerated aqueous solution of β -cyclodextrin ( β -CD) has been investigated in detail. Benesi-Hildebrand analyses indicate that bright phosphorescence arises from a stable 1/S-BrN: β -CD ternary complex in aqueous solution. Of the surfactants employed, cetylpyridinium bromide (CPB) shows much lower phosphorescence enhancement than cetyltrimethylammonium bromide (CTAB) and polyethylene tert-octyl phenyl ether (OP), and sodium dodecylbenzene sulfonate (SDBS) shows higher phosphorescence enhancement than Tween-20 and sodium dodecyl sulfate (SDS), respectively since the intermolecular energy transfer occurs between 1-BrN in the cavity and an aromatic group of a surfactant in a ternary complex. Simultaneously, the external heavy-atom effect of 1-BrN results in the fluorescence quenching of OP and SDBS, In combination with equilibrium constants, surface tension of solutions and spectral structure, a comparison of molecular size shows that part of the hydrocarbon chain of surfactants is included in the cavity of β -CD and the hydrophobic part with the polar head group located outside the cavity coils at the mouth of β -CD cavity. As a result, the excited I-BrN is shielded from the efficient phosphorescence quenching oxygen molecules dissolving in water and intense RTP is obtained.

Properties and analytical application of room temperature phosphorescence of 1-bromonaphthalene induced by p-octylpolyethylene glycol phenylether in aqueous β-cyclodextrin solution

Intense room temperature phosphorescence of 1-bromonaphthalene (1-BrN) induced by p-octylpolyethylene glycol phenylether was studied in aqueous beta-cyclodextrin solution. The mode of inclusion complex formation was approached. The optimal conditions were obtained. Interferences of foreign substances with phosphorescence were examined. The phosphorescence intensity is proportional to the concentration of 1-BrN in the range 0 approximately 5.18 mug ml(-1). The recovery is 90-102% and the relative standard deviation is less than 4.5%. The proposed method is simple and convenient.

Beta-cyclodextrin induced room temperature phosphorescence from 1-bromonaphthalene in the presence of naphthalene and 1-butanol

Abstract Intense room temperature phosphorescence (RTP) from host-guest inclusion complex of beta-cyclodextrin (β-CD) with 1-bromonaphthalene (1-BrN), stabilized by naphthalene (N) and 1-butanol (B), has been investigated. The spectral characteristics of luminescence emission and optimal conditions involved are reported. It has been confirmed that N and B are incorporated into the nonpolar cavity of β -CD as the second and third guests. The extra space inside the cavity is more filled by N and B, and δ -CD more effectively shields 1-BrN from quencher in aqueous solution. B completely hinders the formation of N excimer. Greater rigidity of the complex was achieved. Consequently, much more intense fluorescence and phosphorescence appear in comparison with the ternary β -CD:1-BrN:B complex. The limit of detection is 7.38 × 10 −8 mol 1 −1 for 1-BrN and 1.36 × 10 −6 mol 1 −1 for N.

Phosphorescence-probed study on the association of surfactants with beta-cyclodextrin

Abstract The formation of association complexes between surfactants (S) and β-cyclodextrin (β-CD) has been studied using 1-bromonaphthalene (1-BrN) as a phosphorescent probe. In combination with the spectral structure, phosphorescence lifetimes, surface tension of solutions and association constants of 1:1:1/S:1-BrN:β-CD complexes, a comparison of molecular size shows that the hydrocarbon chain of surfactants is partly included in the cavity of β-CD and the hydrophobic part with the polar head group is located outside the cavity coils at the mouth of the β-CD cavity.

Effect of K4Fe(CN)(6) and K3Fe(CN)(6) on TICT dual fluorescence of sodium p-dimethylaminobenzoate in cetyltrimethylammonium chloride micelle Identification of the magnetic effect in TICT process

Abstract Comparison of the effects of K4Fe(CN)6 and K3Fe(CN)6 on TICT dual fluorescence of sodium p-dimethylaminobenzoate (SDMAB) in cetyltrimethyl ammonium chloride (CTAC) micelle yields a conclusion that the presence of a magnetic effect un favors the TICT process, which is verified by inserting the sample in a stationary magnetic field of 100G in which a decrease in the relative quantum yield of TICT state is observed.