Turn‐On Luminescence Sensing and Real‐Time Detection of Traces of Water in Organic Solvents by a Flexible Metal–Organic Framework

Abstract

The development of efficient sensors for the determination of the water content in organic solvents is highly desirable for a number of chemical industries. Presented herein is a Mg(2+) metal-organic framework (MOF), which exhibits the remarkable capability to rapidly detect traces of water (0.05-5 % v/v) in various organic solvents through an unusual turn-on luminescence sensing mechanism. The extraordinary sensitivity and fast response of this MOF for water, and its reusability make it one of the most powerful water sensors known.

Alkaline Earth Metal Ion/Dihydroxy–Terephthalate MOFs: Structural Diversity and Unusual Luminescent Properties

“…The first result of these investigations was the discovery of [Mg(H 2 dhtp)(H 2 O) 2 ]·DMAc (AEMOF-1). 4 This compound exhibits strong turquoise ligand-based emission arising from radiative deactivation of two closely lying excited states: a locally excited state and a lower lying state populated through excited state intramolecular proton transfer (ESIPT). 5 The ESIPT process involves the transfer of a proton in an electronically excited species from a hydroxyl or an amino group to a carbonyl oxygen through a pre-existing strong hydrogen bond (five-or six-membered ring configuration), Scheme 1.…”

“…6 Indeed, AEMOF-1 showed extraordinary ability for detection of traces of water in various organic solvents via an unusual "turnon" luminescence sensing mechanism that involves enhancement accompanied by a red shift in emission wavelength. 4 Building upon our previous studies on AEMOFs exhibiting ESIPT luminescence, we present herein five new AEMOFs, namely, [Mg 2 (H 2 dhtp) 2 (μ-H 2 O)(NMP) 4 ] (AEMOF-2), [Mg 2 (H 2 dhtp) 1.5 (DMAc) 4 ]Cl·DMAc (AEMOF-3), [Ca-(H 2 dhtp)(DMAc) 2 ] (AEMOF-4), [Sr 3 (H 2 dhtp) 3 (DMAc) 6 ]· H 2 O (AEMOF-5), and [Ba(H 2 dhtp)(DMAc)] (AEMOF-6). The compounds display a noticeable structural diversity adopting 2-D (AEMOF-3) or 3-D frameworks (AEMOF-2, AEMOF-4, AEMOF-5, AEMOF-6) with a variety of secondary building units (SBUs) and network topologies, new H 2 dhtp 2− coordination modes, etc.…”

Signaling of water content in organic solvents by solvatochromism of a hydroxynaphthalimide-based merocyanine dye

“…On the other hand, colorimetric sensors based on merocyanine dyes, such as various isomers of 4-[(4 0 -oxocyclohexa-2 0 ,5 0 -dienylidene)ethylidene]-1,4-dihydropyridine [16,17] and hydroxycoumarin derived dyes [18], and using their unique solvatochromism have been reported. In addition to these, other sensitive sensors derived from various unique materials such as europium-based luminescent nanospheres [19] and a turn-on-type luminescent flexible Mg 2þ metal-organic framework [20] have also been developed.…”

Fluorescence sensor for water based on PET (photo-induced electron transfer): Anthracene-bis(aminomethyl)phenylboronic acid ester

“…[5][6][7][8][9][10][11][12][13] However, this fluorescence quenching system makes it difficult to detect trace amounts of water. Thus, recently, some research groups reported the fluorescence enhancement system [1][2][3][4][13][14][15] based on decomposition reaction [14] and spirolactone ring opening reaction [15] of sensor, or metal-organic framework. [2] On the other hand, the fluorescence sensors based on photo-induced electron transfer (PET) concept have been generally developed for detecting cations such as H + , Na + , K + , Ca 2+ , Mg 2+ , Cu 2+ , Zn 2+ , Pb 2+ , and Cd 2+ as well as neutral organic species in biochemical analyses.…”

“…Thus, recently, some research groups reported the fluorescence enhancement system [1][2][3][4][13][14][15] based on decomposition reaction [14] and spirolactone ring opening reaction [15] of sensor, or metal-organic framework. [2] On the other hand, the fluorescence sensors based on photo-induced electron transfer (PET) concept have been generally developed for detecting cations such as H + , Na + , K + , Ca 2+ , Mg 2+ , Cu 2+ , Zn 2+ , Pb 2+ , and Cd 2+ as well as neutral organic species in biochemical analyses. [24][25][26][27][28][29][30][31][32][33] They are composed of fluorophore skeleton linked to M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 cation binding site such as an amino moiety via a methylene spacer (fluorophore-spacerreceptor structure).…”