A visible-light-active ellagic acid-based titanium-oxo cluster for room temperature chemiresistive sensing

Abstract

In this study, we synthesized a visible-light-active titanium-oxo cluster (TOC), i.e., [ 1), based on ellagic acid (H 4 L). The molecular structure of 1 was determined using single-crystal X-ray diffraction, revealing a cyclodextrin-like tetramer formed by four Ti 4 clusters and dimethylamine cations. Owing to its effective ligand-to-metal charge transfer, 1 exhibited good visible-light absorption ability and photocurrent response, as confirmed by ultraviolet-visible (UV-vis) spectroscopy and photoelectric testing. Structurally, the large number of uncoordinated oxygen sites in 1 serve not only as assembly sites but also as active sites for NO 2 detection. Moreover, 1 exhibited high NO 2 response and excellent selectivity under visible-light irradiation at room temperature. This research provides the first exploration of TOCs in gas sensing applications, expanding their potential beyond traditional uses.

Phenanthroline-Mediated Photoelectrical Enhancement in Calix[4]arene-Functionalized Titanium-Oxo Clusters

“…Titanium-oxo clusters (TOCs) have gained significant attention in recent years due to their fascinating structures and potential applications in photocatalytic water splitting [ 1 , 2 , 3 ], solar cells [ 4 , 5 , 6 ], photocatalytic degradation of pollutants [ 7 , 8 , 9 ], photocatalytic organic synthesis [ 10 , 11 , 12 , 13 ], CO 2 reduction [ 14 , 15 ], and other areas [ 16 , 17 ]. The driving force behind TOC research lies in their ability to serve as structural and reactivity models for TiO 2 materials.…”

Achieving On–Off Ratiometric Luminescence Dynamics in a Nanoporous Eu(III) Metal–Organic Framework for Neopterin Detection

“…Recently, well-designed nanoporous lanthanide(III) metal–organic framework (Ln-MOF) materials have been proven to have excellent luminescence detection capabilities for various markers, because of their remarkable characteristics of high specific surface area and unique electronic structure of nanomaterials, − as well as their unique luminescence properties derived from lanthanide metal centers, along with significant Stokes shift, sharp luminescence emissions, and superior luminescence decay time. − Moreover, the lanthanide(III) ions of a luminescence Ln-MOF martial could be sensitized by the organic ligands via an “antenna effect”, regulating energy transfer of a Ln-MOF in response to the regulation of the organic ligands for achieving the sensitization process. , The remarkable aspect is that some versatile luminescence composites can be encapsulated within a nanoporous luminescence Ln-MOF material, achieving luminescence dynamics performance by weak interactions between the skeleton of material and targeted analytes, thus endowing a nanoporous Ln-MOF material with superior ratiometric luminescence sensing application. − Generally speaking, a luminescence Ln-MOF material exhibits two sensing mechanisms, among which the ratiometric luminescence sensing approach is particularly appealing. − In comparison of the single emission luminescence sensing approach, this approach showcases two fluorescence signals by introducing the targeted analytes into Ln-MOF, demonstrating the excellent self-calibration function and color gradient changes originating from multiple emission centers of luminescence Ln-MOF. This unique feature allows the avoidance of the influence by external environmental factors and enables superior accuracy, sensitivity, and selectivity sensing ability. − It is well-known that three types of sensing mechanisms for ratiometric luminescence approaches have been proposed, including on–off sensing approach with one enhanced luminescence emission intensity and the other quenched emission intensity, on-on sensing approach or off-off sensing approach with two changed luminescence emission intensities in varying degrees and one constant emission intensity and the other alterable emission intensity. − Particularly, as an attractive type of ratiometric luminescence sensing approach, on–off ratiometric luminescence sensing approach has been relatively unexplored in Ln-MOF chemistry. , …”