Highly Sensitive and Selective Rhodamine-Based “Off–On” Reversible Chemosensor for Tin (Sn⁴⁺) and Imaging in Living Cells

Abstract

A structurally characterized new oxo-chromene functionalized rhodamine derivative L1 exhibits high selectivity toward Sn(4+) by forming a 1:1 complex, among other biologically important metal ions, as studied by fluorescence, absorption, and HRMS spectroscopy. Complexing with Sn(4+) triggers the formation of a highly fluorescent ring-open form which is pink in color. The sensor shows extremely high fluorescence enhancement upon complexation with Sn(4+), and it can be used as a "naked-eye" sensor. DFT computational studies carried out in mimicking the formation of a 1:1 complex between L1 and Sn(4+) resulted in a nearly planar pentacoordinate Sn(IV) complex. Studies reveal that the in situ prepared L1-Sn complex is selectively and fully reversible in presence of sulfide anions. Further, confocal microscopic studies confirmed that the receptor shows in vitro detection of Sn(4+) ions in RAW cells.

Two rhodamine based chemosensors for Sn4+ and the application in living cells

“…These indicated that the coordination of probe L 1 with Sn 4+ was chemically reversible. From the molecular structure and spectral results of L 1 , and according to our knowledge [15][16][17][18], a possible sensing mechanism was postulated (Scheme 2). It was supported by the IR spectra and MS spectra.…”

“…To the best of our knowledge, there were few of fluorescent probes used as selective Sn 4+ sensors [16][17][18][19]. Although some fluorescent probes that can detect tin ions have been developed, they may still suffer the influence from other metal ions [16,17].…”

“…Although some fluorescent probes that can detect tin ions have been developed, they may still suffer the influence from other metal ions [16,17]. Han's group has reported a water soluble fluorescent chemosensor for Sn 4+ ; unfortunately, biological application of the probe was not explored [15].…”

A new Rhodamine B-based ‘on–off’ chemical sensor with high selectivity and sensitivity toward Fe3+ and its imaging in living cells

“…[32][33][34][35] On the basis of this interpretation, researchers have synthesized a series of rhodamine derivatives that can be used as fluorescence turn-on chemosensors for the detection metal ions, such as Hg 2+ , Cu 2+ , Sn 2+ , Cr 3+ , Sn 4+ and Pb 2+ . [36][37][38][39][40]26,41,42 Although, many rhodamine based sensors for Fe 3+ have been reported, 43,44 only few of them have been applied in biological systems for the detection of Fe 3+ . 45,46 Due to the paramagnetic nature of Fe 3+ ions, the majority of fluorescent chemosensors for Fe 3+ are fluorescence quenchers, [47][48][49] which certainly hinder fluorescence imaging in vivo and in situ monitoring.…”

Syntheses and structures of three transition metal coordination polymers based on 5-Aminonicotinic acid

“…Coordination polymers (CPs) have currently attracted everincreasing attention because of their intriguing structural topologies and promising applications as functional materials in diverse areas [1][2][3][4][5][6][7][8][9][10][11][12]. By choice and modification of organic linkers and metal centers, metal-organic coordination networks exhibit varieties of interesting molecular topologies, which permits incorporation of many specific properties [13][14][15][16].…”