Simple Bisthiocarbonohydrazones as Sensitive, Selective, Colorimetric, and Switch‐On Fluorescent Chemosensors for Fluoride Anions

Abstract

Bis-thiocarbono-hydrazones are found to be a class of sensitive, selective, ratiometric, and colorimetric chemosensors for anions such as fluoride (F(-)) or acetate (Ac(-)). The sensitivities, or the binding constants of the sensors with anions, were found to be strongly dependent on the substituents appended on the pi-conjugation framework, the delocalization bridge CH==N, the aromatic moiety, and the hetero atom in the C==X group (X=O, S) of the sensors. Single-crystal structures and (1)H NMR titration analysis shows that the --CH==N-- moiety is a hydrogen-bond donor, and it is proposed that an additional CHF hydrogen bond is formed for the sensors in the presence F(-). A sensor bearing anthracenyl groups is demonstrated as a switch-on fluorescent chemosensor for F(-) and Ac(-). The recognition of F(-) in acetonitrile (MeCN) by a sensor with nitrophenyl substituents is tolerant to MeOH (MeCN/MeOH=10:1, v/v) and water (MeCN/H(2)O=30:1, v/v); at these solvent ratios the absorption intensity of the sensor-F(-) complex solution at maximal absorption wavelength was attenuated to half of the original value in pure MeCN.

Experimental and Theoretical Studies on a Thiocarbamide Derivative Containing Schiff Base Groups

“…In view of the bond lengths of N-N and C=N in T1 and T2 (see supporting information S1), all of which are also in agreement with those in the above cited structure [N-N 1.380(2) and 1.381(2) Å, C=N 1.250(3) and 1.266(2) Å]. 26 Four phenyl rings in T1 and T2 are almost planar each other. The dihedral angles between the two phenyl rings in T1 is 15.34(2)º and in T2 is 10.49(2)º.…”

“…As for the N-C single bonds connected with the N-N bonds, in T1, the two bond lengths of N-C are 1.332(12) Å and 1.364(12) Å, respectively, while in T2, the two N-C bond lengths are 1.329(12) Å and 1.345(11) Å, respectively. These four N-C bond lengths are corresponding to those found in a similar structure of 1,5-bis (9-anthracylidene)thiocarbonohydrazide, 26 where the two N-C bond lengths are 1.332(2) and 1.355(3) Å, respectively. In view of the bond lengths of N-N and C=N in T1 and T2 (see supporting information S1), all of which are also in agreement with those in the above cited structure [N-N 1.380(2) and 1.381(2) Å, C=N 1.250(3) and 1.266(2) Å].…”

Anion recognition based on phenolic hydroxyl group in competitive media

“…As shown in Fig. 1, the addition of F -, AcO -and H 2 PO 4 -to DMSO solution of 1 led to obvious changes in the absorption spectrum [29,30]. The absorption peak at 365 nm decreased obviously and a new absorption peak at about 449 nm developed.…”

Sensitive fluorescence probes for dihydrogen phosphonate anion based on calix[4]arene bearing naphthol-hydrazone groups

“…Therefore, a large number of fluorescent molecules for anion recognition were synthesized, and a variety of fluorescent signaling mechanisms have been disclosed [1]. Among them, fluorescent receptors with a hydroxyl [2] or polar NH [3] group attached to a fluorogenic framework have received much attention recently, because anions easily form hydrogen-bond or even take the proton away from these groups, which usually results in big signaling change. However, this kind of fluorescent receptor reported up to now is more sensitive to fluoride anion than to other anions such as H 2 PO 4  , Cl  , Br  , I  , HSO 4  and NO 3  , because the former has stronger basicity [2,3].…”

“…Among them, fluorescent receptors with a hydroxyl [2] or polar NH [3] group attached to a fluorogenic framework have received much attention recently, because anions easily form hydrogen-bond or even take the proton away from these groups, which usually results in big signaling change. However, this kind of fluorescent receptor reported up to now is more sensitive to fluoride anion than to other anions such as H 2 PO 4  , Cl  , Br  , I  , HSO 4  and NO 3  , because the former has stronger basicity [2,3]. Therefore, analysis of H 2 PO 4  by this kind of probes will be limited in the presence of F  , although a few successful examples of sensors for H 2 PO 4  based on other kinds of fluorophores are reported [4].…”