Silver(I)–Carbene Bond-Directed Rigidification-Induced Emissive Metallacage for Picric Acid Detection

Abstract

A new triphenylamine-based tetraimidazolium salt L was developed for silver(I)−carbene bond-directed synthesis of tetranuclear silver(I) octacarbene ([Ag 4 (L) 2 ](PF 6 ) 4 ) metallacage 1. Interestingly, after assembly formation, metallacage 1 showed a nine-fold emission enhancement in dilute solution while ligand L was weakly fluorescent. This is attributed to the rigidity induced to the system by metal− carbene bond formation where the metal center acts as a rigidification unit. The enhanced emission intensity in dilute solution and the presence of the triphenylamine core made 1 a potential candidate for recognition of picric acid (PA). This recognition can be ascribed to the dual effect of ground-state charge-transfer complex formation and resonance energy transfer between the picrate and metallacage 1. For metallacage 1, a considerable detection limit toward PA was observed. The use of such metal−carbene bond-directed rigidification-induced enhanced emission for PA sensing is noteworthy.

Bifunctional {Pb10K2}–Organic Framework for High Catalytic Activity in Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation

“…Furthermore, it is worth emphasizing that the inner wall of voids is characterized by exposed open Pb 2+ sites, protruding K + ions, μ 2 -OH groups, and uncoordinated N pyridine atoms. In addition, it is worth emphasizing that all Pb­(II) ions exhibit distorted semidirected geometries with stereochemically active lone pair electrons (Figures and S1), which is more conducive to the polarization of guest molecules. − …”

Fluorine-Functionalized NbO-Type {Cu2}-Organic Framework: Enhanced Catalytic Performance on the Cycloaddition Reaction of CO2 with Epoxides and Deacetalization-Knoevenagel Condensation

“…At present, the rapid increase of the concentrations of carbon dioxide (CO 2 ) has resulted in more and more serious environmental problems, such as global warming, rising sea level, and deterioration of the ecological environment. − Although the CO 2 emission mitigation with new energy and energy storage as the core provides a feasible method for decarbonization of the energy system, for the sake of energy safety, fossil energy will still exist in the energy structure in a certain proportion for a long time, and its corresponding total CO 2 emission will exceed the capacity of natural carbon sink. Therefore, it is certainly worth developing carbon capture, utilization, and storage technology to treat the waste gas of CO 2 discharged in the industrial production. − For now, the chemical conversion of CO 2 into high value-added chemicals is one of the most attractive and effective strategies to reduce the content of CO 2 , which illustrates that it is still of great practical significance to develop heterogeneous catalytic systems with high stability and high catalytic activity. − MOFs, as heterogeneous catalysts, have shown promising application prospects in the thermal catalytic conversion of CO 2 because of the following advantages: (i) porous structure can shorten the transmission distance between the substrate and the reaction center by enriching the substrate around the catalytic site, so as to improve the reaction rate; (ii) specific pores and highly dispersed catalytic sites are conducive to the highly selective catalytic reaction; and (iii) easy separation and recyclability can greatly reduce the reaction cost. − However, reported MOF-based catalysts also have some disadvantages, such as poor stability and the limitation of their microporosity on the mass transfer in the reaction. Therefore, in order to realize efficient CO 2 catalytic conversion of MOFs under mild conditions, it is of great significance to optimize their structures in the aspects of stability, active sites, and unobstructed void volumes.…”

Nanocage-based {In2Tm2}-organic framework for efficiently catalyzing the cycloaddition reaction of CO2 with epoxides and Knoevenagel condensation

“…S9†). 53–55 Furthermore, NUC-56a also offered the maximum uptake capacity of CO 2 with a value of 90.8 cm 3 g −1 at 273 K and 53.5 cm 3 g −1 at 298 K (Fig. S10†).…”