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We investigate the possibility of tuning the selectivity and sensitivity of SiO 2 /TiO 2 mesoporous dielectric multilayers for the adsorption of analytes with different chemical polarities. The hydrophilichydrophobic balance of the mesoporous SiO 2 layer was controlled by one-pot co-condensation of mixtures of methyltriethoxysilane (MTES) and tetraethyl orthosilicate (TEOS) in variable contents. Infrared spectroscopy analysis combined with water contact angle measurement confirmed the gradual increase of the hydrophobic behavior of the hybrid silica layer obtained by increasing the MTES content, without losing its porosity. Hybrid silica layers included into the dielectric multilayer material enabled controlling the surface properties of the Bragg stacks. UV-visible spectroscopy showed a Bragg peak red-shift. This shift depends on the affinity of the adsorbed molecule toward the functional groups present on the surface of the constituting materials. This procedure enabled the dramatic change of the adsorption properties of the mesoporous dielectric multilayer and correspondingly the optical response of the photonic crystal. Experimental sectionAll chemicals were of analytical grade and used without further purification: tetraethyl orthosilicate (Si(OC 2 H 5 ) 4 , TEOS,

Mesoporous Bragg stacks are able to change color upon infiltration or displacement of liquid compounds inside their porous structure. Reversible switching from transparency to coloration offers additional functionality. Based on Bruggeman's effective medium theory, we derive a transparency master equation, which is valid for bilayers of arbitrary host materials and pore-filling compounds. The transparency condition fixes pore volume fractions such that the effective refractive index is homogenized through the bilayer, hence, through arbitrary layered optical media built from this bilayer. This general concept is applied to the case of switching of hygrochromic coatings made of mesoporous mixed oxide Bragg stacks.

Ionic liquids (ILs) are widely used as reaction and separation media in many technologies due to their unique and advantageous physicochemical properties. Thus, further studies approaching the study of the toxicity of these materials are required. Moreover, they are utilized in devices in which microorganisms such as Shewanella sp. act as biocatalysts. Thus, in this work, the toxicity of 69 ILs on the marine bacterium Shewanella sp. was tested. Specifically, the ILs analyzed were based on the cations imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, oxazolinium, phosphonium, ammonium, and sulfonium, in combination with different anions. The toxicities of this wide group of ILs on Shewanella sp. were determined using two methods: 1) the agar disk-diffusion test and 2) the growth inhibition test in liquid media. The relationship between toxicity and IL chemical structure was elucidated. A decrease in the hydrophobicity of the alkyl chain length was found to be a key factor to reduce IL toxicity. On the other hand, phosphonium-based ILs containing long alkyl chains were shown to be largely incompatible with Shewanella sp.