Study on the kinetic properties of phosphor in deoxycholate aggregates by phosphorescent quenching methodology

Al3+ enhanced room temperature phosphorescence of Pd-porphyrin resided in hybrid supramolecular gels and used for detection of trace Hg2+ ions

Micelle-hybridized supramolecular hydrogels were constructed through the self-assembly of gelator N,N-dibenzoyl-L-cystine (DBC) and micelles formed from a Gemini surfactant (G_12-8-12). A phosphor, palladium meso-tetra (4-carboxyphenyl) porphyrin (Pd-TCPP) and Al³⁺ ions were loaded within the hybrid system. Interestingly, the room temperature phosphorescence (RTP) of Pd-TCPP can be efficiently enhanced and modulated by the concentration of Al³⁺ ions. The enhancement effect could be attributed to the interactions between Al³⁺ and DBC as well as porphyrin, which verified by ¹H NMR analysis. The study of transmission electron microscopy and scanning electron microscopy indicated that a more compact 3D network structure of the gel system was formed upon the addition of Al³⁺. In addition, measurement of critical micelle concentration indicated that Al³⁺ ions increase the surface activity of G_12-8-12 to promote micelle formation, thereby increasing the dispersion of Pd-TCPP in the hybrid gels. Based on the synergistic effect of these results, the non-radiative transition of Pd-TCPP was efficiently inhibited, resulting in highly efficient RTP. Furthermore, the enhanced RTP of as-prepared gel system shows potential application to detect trace Hg²⁺ ions because the RTP can be quenched by Hg²⁺. A linear relationship between RTP against the logarithmic concentration of Hg²⁺ was found over the range of 6 × 10^-8 and 1 × 10^-6 mol/L. The detection limit was found to be 0.017 nmol/L.

Room temperature phosphorescence of five PAHs in a synergistic mesoporous silica nanoparticle-deoxycholate substrate

A synergistic mesoporous silica nanoparticle-sodium deoxycholate (mPS-NaDC) substrate was developed for room temperature phosphorimetry. The synergistic substrate exhibited rapid and strong RTP-inducing ability against temperature variation. NaDC might adsorb on the inner surface of mPS pore by possible hydrogen bonding and protected the triplet state of polycyclic aromatic hydrocarbons (PAHs) with different molecular sizes. Two mPSs named LPMS1 and LPMS2 with pore size of 3.05 and 3.83nm were synthesized and optimized in inducing RTP, and the latter, LPMS2, was selected as an ideal substrate because of its stronger protection ability to the triplet and good stability. Dibromopropane and cyclohexane were also used as assistant phosphorescence-inducers. All results demonstrated the feasibility and application potential of synergistic mPS-NaDC substrate in phosphorimetry. The interaction detail of NaDC and inner surface of selected mPS still needs to be explored in future.

Ion-unquenchable and thermally "on-off" reversible room temperature phosphorescence of 3-bromoquinoline induced by supramolecular gels

Ion-unquenchable and thermally on-off reversible room temperature phosphorescence (RTP) can be induced by entrapping 3-bromoquinoline (3-BrQ) into supramolecular gels formed by the self-assembly of a sorbitol derivative (DBS). In comparison with conventional substrates inducing RTP, the gel state 3-BrQ/DBS can produce strong RTP due to the efficient restriction of the vibration of 3-BrQ. Notably, the rather inconvenient deoxygenation is no longer necessary in the preparation of 3-BrQ/DBS gels. The produced RTP was found to be very fast to reach stable, not depending on the standing time. As a reference, in the liquid state of 3-BrQ/sodium deoxycholate (NaDC), stable RTP can be observed after standing for 5 h. The investigation of RTP quenching indicates that the mechanism of RTP induced by DBS gels mainly involves the microenvironment in which 3-BrQ is located. 3-BrQ was entrapped in the hydrophobic 3D network structure of DBS gels, thereby restricting the motion and collision of 3-BrQ and avoiding RTP quenching and additionally quenching by ions. Furthermore, the RTP of 3-BrQ/DBS gels show an excellent "on-off" effect at 10 or 80 °C. This indicates that the solid DBS gel is beneficial for the preparation of RTP sensor devices.