Second‐Sphere Interaction Promoted Turn‐On Fluorescence for Selective Sensing of Organic Amines in a Tb^III‐based Macrocyclic Framework

Abstract

Guided by as econd-sphere interaction strategy,w e fabricated aT b(III)-based metal-organic framework (MMCF-4) for turn-on sensing of methyl amine with ultralow detection limit and high turn-on efficiency.M MCF-4 features lanthanide nodes shielded in anonacoordinate geometry along with secondary coordination spheres that are densely populated with H-bond interacting sites.Nonradiative routes were inhibited by binding-induced rigidification of the ligand on the second coordination sphere,r esulting in luminescence amplification. Suchr emote interacting mechanism involved in the turn-on sensing event was confirmed by singlecrystal X-rayd iffraction and molecular dynamic simulation studies.T he design of both primary and secondary coordination spheres of Tb(III) enabled the first turn-on sensing of organic amines in aqueous conditions.O ur work suggests apromising strategy for high-performance turn-on sensing for Ln-MOFs and luminous materials driven by other metal chromophores.

Pyrazine functionalization to boost the antenna effect in rare-earth metal–organic frameworks for tetracycline detection

“…This process of RE sensitization for their characteristic emission is known as the "antenna effect". [34][35][36] Herein, we report a generalizable strategy for the synthesis of highly stable RE-MOFs with shp topology and 12-connected RE 9 clusters. By adjusting the dosage of the modulating reagent (2-fluorobenzoic acid), a total of 26 isostructural RE-MOFs, JNU-205-RE and JNU-206-RE (JNU = Jinan University; RE = Eu, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y), were obtained with X-shaped tetracarboxylate linkers, 4,4′,4″,4′′′-benzene-2,3,5,6-tetrayl-tetrabenzoate (BTEB) and 4,4′,4″,4′′′-pyrazine-2,3,5,6-tetrayl-tetrabenzoate (BTTB).…”

Unique Fluorescence Turn-On and Turn-Off–On Responses to Acids by a Carbazole-Based Metal–Organic Framework and Theoretical Studies

“…27,28 To date, however, turn-on sensing-based LMOFs are limited and are confined to detection of only a few certain types of analytes, such as hydrogen sulfide, 29,30 metal cations, 31−33 volatile organic compounds, 34−37 and amines. 38−40 The recent works are focused on turn-on detection of aliphatic and aromatic amines by HOF-20, 39 MMCF-4, 40 and a thiadiazole-based Zr-MOF. 38 Moreover, mechanistic studies on turn-on sensing are scarce and still in their infancy.…”

“…Among them, most are fluorescence-quenching-dependent processes that are known as turn-off sensing. ,− However, some major drawbacks of turn-off sensing, such as loss of signal, poor recyclability, and vulnerability to stimulus from the peripheral environment, are undesirable and will largely limit their reliability for practical applications. By contrast, turn-on sensing based on fluorescence intensity enhancement of LMOFs, bearing a better stimulation tolerance without signal loss, is considered preferable for promoting the sensing ability. , To date, however, turn-on sensing-based LMOFs are limited and are confined to detection of only a few certain types of analytes, such as hydrogen sulfide, , metal cations, − volatile organic compounds, − and amines. − The recent works are focused on turn-on detection of aliphatic and aromatic amines by HOF-20, MMCF-4, and a thiadiazole-based Zr-MOF . Moreover, mechanistic studies on turn-on sensing are scarce and still in their infancy.…”

Construction of multi-hydroxyl/ketone lanthanide metal–organic frameworks for understanding mechanochromic luminescence and high proton conductivity

“…Because of the surprising emission changes the behavior of LnMOFs in response to different stimuli and the relevance of the [Zr 16 -Eu] and [Zr 16 -BPDC-Eu] structures, the luminescence of both types of LnMOFs under mechanical force stimulation was investigated. 27,28 First we studied the luminescence behavior of [Zr 16 -Ln] and [Zr 16 -BPDC-Ln] (Ln = Eu or Tb). The emission of both compounds gradually becomes weaker with the increase of grinding time as shown in Fig.…”