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Despite the current advancements, yet improving the intrinsic structure and external environmental stability of hybrid metal halide perovskite nanomaterials is required for developing efficient perovskite‐based devices. Up‐to‐date, a very attractive method is growing and/or embedding perovskite nanocrystals within organic polymeric matrices, or into porous inorganic and hybrid nano/micromaterials (e. g. metal‐organic frameworks, mesoporous silica, zeolites, and others), favored through confinement effect within the pores. In this review, we highlighted the last two years of research progress on enhancing the stabilization of perovskite nanoparticles based on methylammonium cations. In the future generation of optoelectronic and photovoltaic devices along with other interesting applied fields, it is predicted that an effective way to trigger the widespread use of this type of perovskite nanocrystals may involve combining different functional host materials, acting as a smarter protection method for the guest nanocrystals. [ABSTRACT FROM AUTHOR]

Three new hybrid gated mesoporous materials ( SN3-1, SNH2-2, and SN3-3) loaded with the dye [Ru(bipy)3]2+ (bipy=bipyridine) and capped with different tetrathiafulvalene (TTF) derivatives (having different sizes and shapes and incorporating different numbers of sulfur atoms) have been prepared. The materials SN3-1 and SN3-3 are functionalized on their external surfaces with the TTF derivatives 1 and 3, respectively, which were attached by employing the 'click' chemistry reaction, whereas SNH2-2 incorporates the TTF derivative 2, which was anchored to the solid through an amidation reaction. The final gated materials have been characterized by standard techniques. Suspensions of these solids in acetonitrile showed 'zero release', most likely because of the formation of dense TTF networks around the pore outlets. The release of the entrapped [Ru(bipy)3]2+ dye from SN3-1, SNH2-2, and SN3-3 was studied in the presence of selected explosives (Tetryl, TNT, TNB, DNT, RDX, PETN, PA, and TATP). SNH2-2 showed a fairly selective response to Tetryl, whereas for SN3-1 and SN3-3 dye release was found to occur with Tetryl, TNT, and TNB. The uncapping process in the three materials can be ascribed to the formation of charge-transfer complexes between the electron-donating TTF units and the electron-accepting nitroaromatic explosives. Finally, solids SNH2-2 and SN3-1 have been tested for Tetryl detection in soil with good results, pointing toward a possible use of these or similar hybrid capped materials as probes for the selective chromo-fluorogenic detection of nitroaromatic explosives. [ABSTRACT FROM AUTHOR]

Fluorescent organic-inorganic mesoporous hybrid materials have been prepared and characterised, and their behaviour against nitroaromatic explosives have been tested. MCM-41 silica was used as an inorganic scaffold and pyrene ( P derivative containing trialkoxysilane moieties), dansyl and fluorescein ( D and F derivatives also containing trialkoxysilane groups, respectively) fluorophores have been anchored on hybrid materials by a co-condensation method to obtain a homogenous distribution of dyes into the pores of the support. Six sensing materials have been prepared, of which SP, SD, SF were hydrophilic and SPh, SDh, SFh were hydrophobic. Template-free hydrophilic materials ( SP, SD, SF) were obtained after repeated NH4NO3/ethanol extractions under temperature from as-synthesised ( MP, MD and MF supports, respectively) solids. Hydrophobic materials (SPh, SDh, SFh) were prepared by using excess 1,1,1,3,3,3-hexamethyldisilazane with template-free hydrophilic ( SP, SD and SF) materials. The six final materials displayed the typical emission bands of the grafted fluorophores. In particular, SP and SPh show the typical pyrene monomer (370-420 nm) and excimer (430-600 nm) emissions. SD and SDh exhibit the broad dansyl fluorescence band in the 450-600 nm range, whereas solids SF and SFh present sharp fluorescein emission centred at 525 nm. The fluorescent behaviour of the six final materials was tested in the presence of explosives (pentaerythritol tetranitrate (PETN), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), nitrobenzene (NB), 1,3,5-trinitrobenzene (TNB), 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrophenylmethylnitramine (Tetryl) and picric acid (PA)). Only nitroaromatic compounds were able to induce emission quenching. As a general trend, the quenching degree depended on the nature of the final material. The best response was obtained with explosives PA and Tetryl, which were able to significantly quench the emission of the sensing supports. The observed quenching was ascribed to the π-π stacking interactions between the electron-donor fluorophores and the electron-withdrawing nitroaromatic explosives. When using SPh for Tetryl and PA, the limits of detection were 8.5 and 1.4 ppm, respectively, whereas they were 14.4 and 1.2 ppm for SDh. Principal component analysis algorithms were applied to the fluorescence measurements taken with the six hybrid materials and the seven explosives. The obtained score plot showed well-defined clusters for the seven explosives tested. Finally, solid SDh was applied to detect trace amounts of Tetryl in soil samples with good results. [ABSTRACT FROM AUTHOR]