Further Understanding of the Reactivity Control of Bisphosphonates to a Metal Source for Fabricating Highly Ordered Mesoporous Films

Mesoporous metal organophosphonates having embedded organic functions are a promising platform to hybridize organics and non-siliceous inorganic frameworks in their molecular scale. However, the reactivity between a bisphosphonate and a metal source is dramatically different for their combination and then hampers to construct ordered mesoporous structures even when using amphiphilic organic molecules. By proposing an advanced method to adjust such reactivity, we recently succeeded in fabricating ordered mesoporous aluminum organophosphonate (AOP) films with chemically designable benzene units inside their hybrid frameworks. The reactivity of the organically bridged bisphosphonates has been controlled by utilizing dissimilar reactivities of acid-base pairs like P-OH and P-OEt groups to AlCl₃ . Here, we further prove our reactivity-control concept through the introduction of organic groups, such as those having symmetric thiophene, asymmetric amide, and hydrophilic ether units. Liquid-state ³¹ P NMR measurements further clarified the usefulness of the control of the -OH/ -OEt ratio in the same bisphosphonate molecules for obtaining highly ordered mesostructured AOP films.

Evaporation-induced Self-assembly Process Controlled for Obtaining Highly Ordered Mesoporous Materials with Demanded Morphologies

A large number of periodic mesoporous materials have been reported using amphiphilic organic molecules with increasing development of synthetic methods for mesostructural, morphological, and compositional designs. The evaporation-induced self-assembly (ESIA) process to fabricate ordered mesoporous films is one of the most essential synthetic methods, which has extensively been applied for obtaining a wide variety of samples (e.g., films and monoliths, including powders). It contains complicated physical variations and chemical reactions, but has been simply explained by several research groups. However, a current, exact understanding of such complicated systems should be given with respect to all the variations and reactions. In this article, I have mainly surveyed the exact EISA process by considering the difference between simple and controlled EISA processes on the basis of my own experiments. I believe that the insights are consequently helpful for obtaining highly ordered mesoporous materials with demanded morphologies.

Insights into mesoporous metal phosphonate hybrid materials for catalysis

Mesoporous metal phosphonates have received increasing attention as promising heterogeneous catalysts due to their abundant framework compositions and controllable porosity.

Electron microscopic study on aerosol-assisted synthesis of aluminum organophosphonates using flexible colloidal PS-b-PEO templates

A wide variety of synthetic approaches from homogeneous precursor solutions have so far been developed for precise structural design of materials in multiscale. In organic templating approaches for porous materials design, we have recently developed a new approach to fabricate colloidal polystyrene-block-poly(oxyethylene) (PS-b-PEO) templated large pores that can be controlled in thick films of aluminum organophosphonate (AOP). In this study, we extended this approach using colloidal PS-b-PEO aggregates to aerosol-assisted synthesis for the fabrication of spherical particles. Structural variations (morphology and porous structure) depended on the synthetic conditions, which were mainly investigated by using electron microscopies (SEM and TEM). In addition to the insight on the colloidal PS-b-PEO templating of spherical pores in AOP spheres, it was found that colloidal PS-b-PEO aggregates were flexible for further design of pore shape that was strongly affected by external morphology. In this context, we proposed this method as flexible colloidal PS-b-PEO templating to fabricate unusual macroporous structures during morphological control from precursor solutions containing colloidal PS-b-PEO aggregates. The insights will be promising for precise construction of unique devices using porous materials templated by colloidal organic aggregates. In addition, we found a useful water adsorption-desorption behavior over the macroporous AOP bulky powders when the macropores were connected through large pores, which is also significant for future development of AOP-based porous materials.