Perspectives on the Influence of Crystal Size and Morphology on the Properties of Porous Framework Materials

Miniaturization is a key aspect of materials science. Owing to the increase in quality experimental and computational tools available to researchers, it has become clear that the crystal size and morphology of porous framework materials, including metal-organic frameworks and covalent organic frameworks, play a vital role in defining the physicochemical behaviour of these materials. However, given the multiscale and multidisciplinary challenges associated with establishing how crystal size and morphology affect the structure and behaviour of a material–from local to global structural modifications and from static to dynamic effects–a comprehensive mechanistic understanding of size and morphology effects is missing. Herein, we provide our perspective on the current state-of-the-art of this topic, drawn from various complementary disciplines. From a fundamental point of view, we discuss how controlling the crystal size and morphology can alter the mechanical and adsorption properties of porous framework materials and how this can impact phase stability. Special attention is also given to the quest to develop new computational tools capable of modelling these multiscale effects. From a more applied point of view, given the recent progress in this research field, we highlight the importance of crystal size and morphology control in drug delivery. Moreover, we provide an outlook on how to advance each discussed field by size and morphology control, which would open new design opportunities for functional porous framework materials.

Mono and Tri-cationic Imidazolium Salts: Use as Stabilizers for Silver Nanoparticles and Anticancer Study

In present strudy, the synthesis and characterization of monocationic 1,3-tetradecylimidazolium; [(C14)2Im]Br and tricationic benzene centered tris-tetradecyl/hexadecyl imidazolium bromide salts; i.e. [(C14)3C6H3Im]Br3 and [(C16)3C6H3ImBr]Br3 is reported. The stabilizer role of imidazolium salts to prepare silver nanoparticles (AgNPs) via chemical reduction method was investigated. To understand the reaction medium effect on the size and morphology control of AgNPs, monophasic (aqueous medium) and biphasic (DCM/H2O) approaches were applied. The morphology control was noticed for AgNPs protected with [(C14)3C6H3Im]Br3 (show sphere like morphology) and [(C14)2Im]Br (show dendritic structures) via biphasic approach. A clear variation in the size and morphology of AgNPs was noticed by varying the type of stabilizers and reaction medium. It was also observed that AgNPs were formed and stabilized only in aqueous medium in both approaches, thus it is assumed that AgNPs surfaces were protected by imidazolium salts with bilayer fashion. Anticancer activity of imidazolium salts was performed by MTT assay against HeLa cancer cell lines. The result shows that cytotoxic activity of tricationic [(C14)3C6H3Im]Br3 was more potent than that of monocationic [(C14)2Im]Br. The outcome suggests that there is an urgent need to develop new polycationic imidazolium salts for various chemical and medicinal applications.

One-pot co-condensation strategy for dendritic mesoporous organosilica nanospheres with fine size and morphology control

A one-pot co-condensation strategy was developed for dendritic mesoporous organosilica nanospheres with fine size and morphology control.

Preparation and Microstructures of Nano-Porous SiO2 Thermal Insulation Materials by Freeze-Casting of SiO2 in TBA/H2O Suspensions

A kind of porous SiO2 bulk materials with pore size distributed in nano and micron scales has been fabricated by freeze-casting of SiO2 nano-size powders in TBA (tert-butyl alcohol)/H2O suspensions. The content of TBA in the well mixed TBA/H2O binary co-solvent plays an important role in size and morphology control of the pores in the obtained SiO2 monolithic materials, since the ratio of TBA/H2O determines the competition of crystallization of TBA and ice, therefore, the microstructure of the monolithic SiO2. It was found that the content of TBA in the range from 30 to 40% was suitable for formation of more nano-pores in the SiO2 monolith. The insulation materials freeze-casted from the suspension of SiO2 in 13wt% and TBA in 40wt% has the density of 0.17g/cm3, and the specific surface area of 282m2/g. The pore size has a trimodal size distribution with three mean diameters of 15nm, 100nm and 4μm, respectively.