As an inorganic sunscreen material, nano-titanium dioxide (nano-TiO₂) owns broad prospects in sunscreen cosmetics for its small size, non-toxicity, strong covering ability, UV absorption and scattering abilities, etc. Nano-TiO₂ has high photocatalytic activity, so it will go through a series of complex chemical reactions under light irradiation and cause damage to its surrounding agents. In addition, it is hard to disperse in various aqueous and non-aqueous mediums due to its high surface energy and hydrophobic property. In order to apply nano-TiO₂ to cosmetics effectively and safely, its surface modification is necessary. This paper reviews nano-TiO₂’s preparation, modification, and its application in sunscreen cosmetics.

Due to an increasing demand for miniaturized electronics, on-surface molecular assembly has progressed rapidly for its advantage of fabricating highly organized patterns at nanoscale. In this regard, on-surface metal-organic architectures of bipyridine derivates have been invoked owing to moderate strength and flexible direction of metal-ligand interaction. Despite intensive researches on self-assembled monolayers of p-substituted bipyridine derivates and their metal complexes, few reports have addressed the structural evolution of m-substituted ones. In this paper, a 4,4'-dinonyl-2,2'-bipyridine with two substitutional alkyl chains at m-positions was employed as a ligand for construction of metallosupramolecular architectures with zinc and copper centers via metal coordination, respectively. A microscopic observation on metal directed structural transformations of 4,4'-dinonyl-2,2'-bipyridine arrays, together with merits from previous related researches, reveals more understanding on the rational design of on-surface bipyridine derivates based metal-organic architectures.

In this study, we report the application of magnetic metal-organic frameworks as a novel adsorbent for fast removal of Pb(II) ions from aqueous solution in view of adsorption isotherms, kinetics, thermodynamics, desorption, and adsorbent regeneration. The adsorbent was characterized by PPMS, XRD, TEM and N₂ adsorption/desorption measurement. The adsorption follows pseudo-second-order kinetics model and fits the Freundlich adsorption model with the adsorption capacity of 612 mg g^–1 for Pb(II) ions. It is a spontaneous and endothermic process controlled by positive entropy change. The used Fe₃O₄/HKUST-1 could be regenerated effectively and recycled at least four times without significant loss of adsorption capacity.