Multichannel Chromogenic and Chiral Anions Recognition by Imidazolium Functionalized BINOL Derivatives

Abstract

New imidazolium/benzimidazolium‐containing receptors (R)‐1–(R)‐6 were developed as multifunctional receptors for both chromogenic and chiral anion recognition through multichannel. The ?uorescence spectra of (R)‐1 showed a distinct and intense peak at 454, 474 nm with AcO− and F−, respectively, indicating that (R)‐1 can be applied to the detection of fluoride and acetate ions by naked eye. Receptor (R)‐5, containing a lipophilic dodecyl appendage at imidazolium nitrogen, exhibited larger fluorescent responses than (R)‐1. The ratio of fluorescence enhancement for (R)‐5 with AcO− (I460/I369=16) and F− (I485/I369=11) was 32‐fold and 18‐fold over (R)‐1 with AcO− (I454/I369=0.5) and F− (I474/I369=0.6), respectively. Less electron‐deficient benzimidazolium receptor (R)‐2 only gave fluorescence enhance at 555 nm for F−. Only chelation enhanced quenching (CHEQ) effect was obtained in the case of mono‐imidazolium receptor (R)‐4. Furthermore, (R)‐1 and (R)‐5 displayed a remarkable binding ability for the t‐Boc alanine anion with interesting enantioselectivity [KL/KD=4.5 for (R)‐1 and 4.1 for (R)‐5)], whereas only negligible enantioselectivity ability (KL/KD=1.1) was obtained by using C1 symmetric receptor (R)‐4.

A fluorescent sensor based on binaphthol-quinoline Schiff base for relay recognition of Zn2+ and oxalate in aqueous media

“…The absorption band at 394 nm of L 1 can be assigned to the absorption of Schiff base linked binol moiety. On gradual addition of Zn 2+ to L 1 solution, the absorption intensity of L 1 at 394 nm decreased gradually, concomitantly, two new absorption bands centered at 357 nm and 443 nm emerged and gradually increased, and they can be attributed to the deprotonated amide-quinoline 13 and phenolic binol Schiff base, 15 respectively.…”

Chiral Heterocycle-Based Receptors for Enantioselective Recognition

“…This is a result of the reduction of the steric factor between the BINOL unit and imidazolium due to the flexible methylene linker. Yu et al [24] developed the imidazolium/benzimidazolium-containing receptors, (R)-168, (R)-169, (R)-170, (R)-173, and (R)-176. At first, MOM-protected boronic acid ester, (R)-164 upon the N-arylation with imidazole derivative or benzimidazole yielded the respective coupled products (165-167) followed by methylation to give the desired hosts, 168-170 (Scheme 29).…”

“…In the last few decades, strategies and methods for synthesizing simpler organic compounds that mimic the biological receptors havebeen the prime focus in this research area [19][20][21]. Thus, the artificial receptors having diverse chiral backbones with different elements of chirality [22][23][24][25], incorporating aromatic/heteroaromatic alicyclic rings [26][27][28] in the core structural motif with multiple functionalities [29] have been reported. The receptors containing heteroaromatic ring/heteroalicyclic rings have attracted widespread interest due to their excellent chiral discriminating ability [30].…”

“…The present review article presents a detailed account of the recent developments in the design and synthesis of various chiral receptors with heterocyclic motif such as pyridine [18], chromene [32,33], imidazole [34], benzimidazole [35,36], furan [37], thiophene [38], oxazole [22][23][24][25] etc. and its application in the enantioselective recognition of different classes of chiral analytes [39,40].…”

Optically Active Helical Poly[(S)‐3‐vinyl‐2,2′‐dihydroxy‐1,1′‐binaphthyl]: New Ligand for Asymmetric Addition of Diethylzinc to Aryl Aldehyde

“…Using polymeric catalysts also makes it possible to carry out reactions in flow reactors or in flow membrane reactors for large-scale production. Chiral 1,1'-bi-2-naphthol (BINOL) is one of the most useful ligands [2][3][4] and has made a considerable contribution to asymmetric synthesis. [5][6][7][8][9][10][11][12][13][14][15] So far, several types of the binaphthyl-based chiral polymer ligands have been reported.…”