Interfacial Self-Assembly of Closely Packed Nanoparticle Arrays of Silica@Multiporphyrin Hybrids as Light-Sensitizers for Dye Degradation and Viologen Photochromism.

Abstract

Light-sensitizer functionalized organic-inorganic hybrid materials have attracted much attention owing to their potential applications in the fields of optoelectronics, heterogeneous catalysis, sensors, and nanotechnology. Here, an interfacial self-assembly of zero-dimensional (0D) silica@multiporphyrin array nanohybrids and their 3D Langmuir-Blodgett (LB) films is reported. Photoactive tetrapyridylporphyrin (TPyP) was first assembled on the silica nanoparticles' surfaces via silane, substitution, and coordination reactions to produce nanoSiO2 @(Pd-TPyP)n hybrids. Then, the Cd2+ -nanoSiO2 @(Pd-TPyP)n monolayers and LB films were constructed on the CdCl2 subphase surface. These monolayers and LB films displayed stronger stability, as well as more uniform and closely packed nanoparticle arrays compared with those prepared on the pure water surface, owing to the formation of strong network-like Pd- and Cd-TPyP coordination units, which significantly enhanced the nanoparticles' interaction. Further, compared with that of the 0D nanoSiO2 @(Pd-TPyP)n hybrids, the degradation efficiency was nearly 20 times higher when the hybrids' LB films were used as light-sensitizers for the photocatalytic degradation of RhB. Finally, flexible photochromic devices were constructed by using the LB films sandwiched between two electrodes, which displayed a reversible photoinduced redox reaction of viologen together with a color change process. Because TPyP was strongly immobilized on the nanoparticles' surfaces and the particles were connected through the Py-Pd2+ -Py and Py-Cd2+ -Py coordination units with the 3D network-like architecture, the present nanohybrids and LB films had good stability and reusability.