Highly Fluorescent Mesostructured Films that consist of Oligo(phenylenevinylene)–Silica Hybrid Frameworks

Abstract

Highly fluorescent and visible‐light‐responsive mesostructured organosilica films are successfully obtained by acidic sol–gel polycondensation of oligo(phenylenevinylene) (OPV)‐bridged organosilane and tetraethoxysilane precursors in the presence of a template surfactant. The OPV‐bridged organosilane precursors with different lateral alkoxy substituents, hexyloxy and 2‐ethylhexyloxy, and no substituent, are synthesized by Rh‐catalyzed silylation of corresponding aromatic iodides. From the organosilane precursors, three kinds of mesostructured OPV–silica hybrid films are prepared by spin‐casting using evaporation‐induced self‐assembly. UV‐vis absorption and fluorescence behavior of the OPV–silica hybrid films show that the optical properties and intermolecular interactions of the OPV moieties embedded within the organosilica frameworks strongly depend on the lateral alkoxy substituents in the precursors. The hexyloxy and 2‐ethylhexyloxy substituents prevent aggregation of the OPV units in the organosilica frameworks; this result leads to high fluorescence quantum yields of 0.48–0.61 and 0.63–0.66, respectively, while non‐substitution leads to lower fluorescence quantum yields of 0.25–0.34. Fluorescence decay profiles of the organosilica hybrid films also confirm a suppression of the aggregation of OPV moieties by the lateral substituents. These mesostructured organosilica films with significant optical properties in the visible‐light region are promising as a new class of phosphor materials.

Hierarchically structured biphenylene-bridged periodic mesoporous organosilica

“…The pore-size distribution peaks at a pore diameter of 13.8 nm. The 13 C and 29 Si NMR data ( Fig. S5 †) of the sample F127-cubic-250 Bp-PMO are consistent with those obtained from the sample F127-circular-250 Bp-PMO.…”

“…DFT pore size distributions were calculated using a SiO 2 kernel assuming a cylindrical pore geometry for the F127-circular hexagonal sample and a cylindrical/sphere pore geometry for the F127-cubic sample. Solid-state 13 C and 29 Si NMR measurements were performed using a Bruker Avance III 500 spectrometer. The fluorescence spectra were measured with a fluorescence spectroscopy system (PTI 814 from Photon Technology international) with a xenon arc lamp.…”

“…11 Recently, several PMO materials with optical properties have been reported, and among them, PMO thin films show interesting potential for use as fluorescent materials. [12][13][14][15] For example, Goto et al investigated the fluorescence properties of aromatic-bridged PMO films and found that biphenyl-bridged PMO exhibited exceptionally high fluorescence quantum yield (0.45) compared with benzene-, naphthalene-, and anthracene-bridged PMO films (0.03-0.09). 12 A number of studies on biphenyl-bridged PMOs in powder form have been published.…”

Aerosol-assisted synthesis of mesoporous organosilica microspheres with controlled organic contents

“…Accordingly, the presence of organic groups in the frameworks leads to the increase in wall thickness because the volume of the ethane fragment (Si-C-C-Si in Samples 2 and 3) is larger than that of the pure silica framework (Si-O-Si in Sample 1). This would be related to the increase in pore-to-pore distance, as indicated in [42,43]. The N 2 adsorption-desorption isotherms of the PMO spherical particles are shown in figure 5.…”

Formation of hexagonal and cubic fluorescent periodic mesoporous organosilicas in the channels of anodic alumina membranes

“…The noteworthy point regarding the PMO materials is the successful integration of versatile organic groups into their pore walls, such as alkyl, unsaturated and aromatic systems. [6][7][8][9] The resulting functional porous materials can interact in different ways with guest molecules that reside in the pores, leading to potential applications of PMOs as catalysts, 10,11 adsorbents, 12,13 and optical [14][15][16][17] systems. In recent years, great efforts have been made towards developing novel PMOs with photoactive or electroactive functions within their frameworks.…”