Photoinduced versus spontaneous host–guest electron transfer within a MOF and chromic/luminescent response

Abstract

The MOF shows charge-transfer sensitized Eu(iii) emission and spontaneous/photoinduced guest-to-host electron transfer, which allow chromic and luminescent sensing of NH3 (luminescence turn-off) and O2 (luminescence turn-on).

dl-Serine Covalently Ornamented and Ln3+-Incorporated Arsenotungstates with Fast-Responsive Photochromic and Photoinduced Luminescent Switchable Behaviors

“…As expected, the W V sites were validated in UV-irradiated samples 1 , 2 , and 3 via the EPR study, with particular signals observed at g = 1.945, 1.938, and 1.940, respectively (Figure ). It was emphasized that signals with g = 2.00 of the three hybrids were recorded before irradiation, consistent with the existence of small amounts of dl -Ser free radicals excited under natural light. , This signal remarkably grew stronger postirradiation, indicating that the compounds were sensitive to light, producing dl -Ser free radicals under natural light, resulting in the creation of a more conducive way to the photochromic process. The results of EPR analyses are consistent with similar systems reported in the literature. ,, Simultaneously, the rate constants of the first-order kinetics of the reflection at ca.…”

“…This illustrates that there is an additional quenching process. Due to the part overlap between the emission band (600–700 nm) of Ln 3+ and the obvious band of the colored sample (Figure S19), there is an ET process between Ln 3+ and the colored sample, leading to the rapid kinetics of luminescence quenching …”

“…Interest in stimuli-responsive materials, serving as a sort of intelligent and captivating materials, has intensively expanded, given their functional tunability of physicochemical properties upon different external triggers, which have been applied in the fields of multifunctional logic gates, medical diagnosis and memory media, and so on. − Among these, fluorescent molecular switches have undergone substantial and remarkable development because of their potential capacities such as rapid response, excellent stability, and obvious color changes, − easily triggered by various means of stimuli such as UV–vis light, chemical vapor, heat, and electrochemically. − Until now, polyoxometalates (POMs), analogous to electron reservoirs, have been proven as promising candidates in the synthesis of multifunctional materials due to the following characterized merits: − (i) well-defined structures in good diversity, (ii) compositional adjustability, (iii) easy to implant functional organic ligands as well as metal centers (transition metals or lanthanide (Ln 3+ )), and (iv) benign redox activities. The above characteristics also undoubtedly render the POMs to be exploited as promising candidates in the field of fluorescent materials.…”

Anion-Afforded Functions of Ionic Metal–Organic Frameworks: Ionochromism, Anion Conduction, and Catalysis

“…Remarkably, the counterions can be versatile handles for functional manipulation. They can bring in new functions (such as catalytic, photoluminescent, , and sensing , functions) by themselves or in cooperation with other components. Some ion-exchangeable IMOFs have been demonstrated to be efficient absorbents or colorimetric/luminescent sensors for toxic/radioactive oxoanions − or other ionic pollutants. , Moreover, ion exchange can be used to tune the porosity, to modulate intrapore interactions, and to incorporate functional species, thus providing a powerful methodology to achieve better or new functions.…”

Fluorescence analysis for characterizing the alkali stability of metal–organic frameworks: an informative complement to X-ray diffraction

“…Metal-organic frameworks (MOFs), an emerging kind of porous material built from metal nodes and organic links, [1][2][3] have aroused great scientific interest. Their structural designability, diversity, tunability, and porosity endow MOFs with potential applications in gas adsorption and separation, [4][5][6][7] chemical sensing, [8][9][10][11][12][13][14] photonics, 15,16 heterogeneous catalysis, [17][18][19][20][21] proton conduction, [22][23][24][25] etc. The functional performance of MOFs is highly dependent on their crystalline porous structures, and the structural lability to humidity, acids, bases and other external stimuli often limits their practical applications.…”