Development of a highly selective cell-permeable ratiometric fluorescent chemosensor for oxorhenium(v) ion

Abstract

A novel 6-(2-pyridinyl)-5,6-dihydrobenzimidazo[1,2-c]quinazoline (HL) serves as a first-time highly selective and sensitive ratiometric fluorescent chemosensor probe for oxorhenium (ReO(V)) ion in acetonitrile : water = 9 : 1 (v/v) at 25 °C. The decrease in fluorescence at 410 nm and increase in fluorescence at 478 nm with an isoemissive point at 444 nm in the presence of ReO(V) ion is accounted for by the formation of mononuclear [ReOL(2)Cl] complex, characterized by physico-chemical and spectroscopic tools. The fluorescence quantum yield of the chemosensor (HL) was only 0.198 at 410 nm, and it increased more than 3-fold in the presence of 2 equiv. of the ReO(V) ion at 478 nm. Interestingly, the introduction of other metal ions and relevant anions caused the fluorescence intensity at 478 nm to be either unchanged or weakened. The fluorescence-response fits a Hill coefficient of 2.088 indicates the formation of a 1 : 2 stoichiometry for the L-ReO(V) complex. In the concentration range of 0-20 μM of oxorhenium(V) species calibration graph was linear with correlation coefficient (R) of 0.99994 and the calibration sensitivity was found to be 4.0 × 10(-7) M. The cellular image in the confocal microscope clearly indicated the presence of ReO(V) in Candida albicans cells using this chemosensor (HL).

Effect of metal oxidation state on FRET: a Cu(i) silent but selectively Cu(ii) responsive fluorescent reporter and its bioimaging applications

“…S2 ESI †). 1 H NMR (400 MHz, CDCl 3 ): 8.22-8.20 (d,1H,CHvN);2H);1H);4H); 7.01-6.99 (d,1H);1H);1H);8H,4CH 2 ); 12H,4CH 3 ) (Fig. S3 ESI †).…”

“…1 H NMR (400 MHz, CDCl 3 ): 8.24-8.22 (d,1H,CHvN); 8.09-8.06 (d, 2H); 7.94-7.92 (d, 1H); 7.43-7.38 (m, 4H); 7.02-7.00 (d, 1H); 6.94-6.87 (m, 1H); 6.58-6.54 (d,1H);8H,4CH 2 ); 1. 12H,4CH 3 ).…”

A water soluble Al3+ selective colorimetric and fluorescent turn-on chemosensor and its application in living cell imaging

“…[21][22][23][24][25][26][27][28][29][30] Among them, a small number of CHEF type sensors [21][22][23][24][25] is accessible though the sensing of metal ions by means of the chelation enhanced fluorescence (CHEF) mechanism, which is an active area of research today. [31][32][33][34][35] In the present paper, we design a CHEF type Schiff base probe named as 1-[[(2-furanylmethyl)imino]methyl]-2-naphthol (1-H) having hard donor centers to facilitate the chelation of Al 3+ as a hard centre. It consists of two parts: one is a signaling moiety which is a naphthalene entity and the other is the binding site having the hydroxyl and imine groups.…”

A ratiometric fluorescent chemosensor for iron: discrimination of Fe2+ and Fe3+ and living cell application

“…The development of selective and sensitive fluorescent probes for detection of biologically relevant ions not only in vitro detection but also for in vivo recognition has been the cynosure among the chemists during recent years due to the ease of detection, sensitivity, and tenability of fluorescence method over other techniques. [4][5][6][7][8][9] Interestingly, various sensors specific for Fe 3+ have been reported, 10-15 but to the best of our knowledge, a ratiometric fluorescent sensor specific to both Fe 2+ and Fe 3+ cations is still unexplored. Moreover, the literature reports either single point CHEF (chelation enhanced fluorescence) [16][17][18][19][20] or quenching studies 21 to sense only Fe 3+ except for one reporting a ratiometric sensor.…”