Cyclic Trinuclear Copper(I) Complex Exhibiting Aggregation-Induced Emission: A Novel Fluorescent Probe for the Selective Detection of Gold(III) Ions

Abstract

Coordination complexes with aggregation-induced-emission (AIE) behavior has drawn much attention because of their promising applications. Conventionally, the AIE-active metal–organic complexes are prepared from an AIE-active organic ligand, and the construction of such coordination complexes from aggregation-caused-quenching (ACQ) ligands is still challenging. Herein, we have synthesized two new cyclic trinuclear complexes (CTCs), namely, 1 and 2, from copper­(I) and silver­(I) and a ACQ ligand [4-(3,5-dimethyl-1H-pyrazol-4-yl)­benzaldehyde, HL]. (1) exhibited AIE behavior, and the emission intensity is enhanced ∼20 times when it aggregates, which can be attributed to its tight packing and multiple intermolecular hydrogen bonds that restrained the intramolecular rotation, as confirmed by single-crystal X-ray diffraction analysis. On the other hand, (2) displayed ACQ effects, and the emission intensity is decreased ∼5 times when it aggregates. This ACQ behavior of 2 is related to its loose packing and free rotation of the ligand in crystals, resulting in nonradiative decay and fluorescence quenching. Interestingly, the CTCs 1 and 2 both exhibited a good affinity to gold­(III) ions, allowing selective detection and sensing of gold ions. More importantly, the 2 shows a good limit of detection (3.28 μmol/L) and an ultrafast responsive time (∼2 s). Our studies pave a new route to designing novel AIE-active coordination complexes and further exploring the functionality of CTCs.

Selective and rapid extraction of trace amount of gold from complex liquids with silver(I)-organic frameworks

“…34). Such PL quenching might be attributed to the strong metal-metal interactions between Au(III) and Ag(I)-CTUs in the frameworks, resulting in enhancement of radiative decay 28 . To further prove this hypothesis, we prepared a COF, TFPT-BTAN (see the SI) 33 as a reference with similar pore size and nitrile groups but without Ag(I)-CTUs.…”

“…Although a few MOFs have been demonstrated with the capability of gold adsorption, to our best of knowledge, MOFs that can concentrate ultra-trace gold (<20 ppb) from complex liquid have rarely reported so far (See Supplementary Table 12) [21][22][23][24][25][26][27] . Recently, we found that a Ag(I) cyclic trinuclear unit (CTU) can be used for rapid and selective sensing of Au(III) ion with a low limit of detection (LOD) of 650 ppb via strong metallophilic attractions 28 . We hypothesize that the incorporation of Ag(I)-CTU into MOFs may be a promising strategy for improving the affinity of MOFs toward gold.…”

Strong visible light-absorbing BODIPY-based Cu(i) cyclic trinuclear sensitizer for photocatalysis

“…In our previous studies, we found that the modification of the pyrazole ligand significantly altered the PL properties of Cu-CTCs. 20,36 Boron dipyrromethene (BODIPY) is an organic dye with excellent PL properties including strong visible light adsorption, high photo-stability, and high quantum efficiency. [37][38][39][40] Thus, we envisioned that the incorporation of the BODIPY motif in Cu-CTCs may address the above-mentioned issues and hopefully become the first example of a Cu-CTC-based PS.…”

Construction of Cu(I)-Organic Frameworks with Effective Sorption Behavior for Iodine and Congo Red

“…These functional hybrids are usually equipped with permanent porosities and present distinct physicochemical properties in sorption, separation, catalysis, photoluminescence, magnetism, and so on. − In the process of acquisition of desirable MOFs, many external factors have a great influence on the regulation of diverse architectures, among which the utilization of organic linkers could be considered as the most important one. − Especially, the N-donor molecules, exemplified by the pyridine and azole derivatives, are largely employed to assist the construction of promising MOFs by virtue of their merits in satisfactory coordination geometry and abilities. − According to the hard and soft (Lewis) acid and base theory, the “soft” N atom has a high affinity to the “soft” cation like Cu + , thus giving rise to a large number of robust Cu­(I)-based MOFs with outstanding physical performance. The works on Cu­(I) cyclic trinuclear complexes (CTCs) are representative of such compounds. − The combination of closed-shell coinage metal with angular ditopic anionic linkers such as pyrazolate and 1,2,4-triazolate has afforded a series of trinuclear metallocycles with M–M interactions featuring excellent photoluminescence behaviors. In addition, the assembly of copper-based porous networks for selective guest sorption is a trend in terms of seeking new adsorbents and separators.…”