Synthesis and Anion Binding Properties of a Novel 1,8-dipyrrolecarbazole Schiff-base

Abstract

New anion receptor N 1 ,N 8 -bis[1H-pyrro-2-yl-methylidene]-3,6-dichloro-9H-carbazole-1,8-diamine (3) was synthesized and its binding properties towards anions (Cl -, Br -, AcO -and H2PO4 -) investigated by UV/Vis spectroscopy. In order to find the most stable structure of receptor 3, geometries of all possible isomers of 3 were optimized by the DFT/B3LYP method. It has been determined that receptor 3 forms complexes with a 1:1 stoichiometry with all the studied anions and no significant selectivity with respect to anion geometry was found. However, 1,8-dipyrrolecarbazole Schiff-base 3 binds oxoanions (H2PO4 -and AcO -) more strongly than spherical halogenide (Cl -and Br -) anions.

Two macrocycle-based sensors for anions sensing

“…In the recognition of OAc − using 2 as a host, the K SV value (1.2 × 10 4 M −1 ) from the fluorescence method and the K S value (2.3 × 10 4 M −1 ) from the ultraviolet method are consistent with each other 60 . Compared to the literatures, the binding constants of 2 to OAc − are in the middle of the values of literatures reported, and the detection limit of 2 to OAc − is close to the minimum in literatures reported (the binding constants and detection limits of these reports being in the range of 6.9 × 10 2 M −1 to 5.9 × 10 5 M −1 and 1.2 × 10 −7 mol/L to 1.0 × 10 −6 mol/L) 10,11,19–21,23,24,26 .…”

Macrocyclic versus open-chain carbazole receptors for carboxylate binding

“…As can be concluded from the p K a values (in DMSO) of pyrrole (23.0), indole (20.9) and carbazole (19.9), 32 the acidity of the pyrrole ring can be increased not only by attaching electron-withdrawing groups but also by conjugation with the benzene ring. 33 The groups of Jurczak, 34 Sessler, 35 and Gale 36,37 and our group 38–40 have used the carbazole ring as an effective component of anion receptors. The carbazole ring is used not only because of its higher acidity but also for its rigidity.…”