Inclusion Complexes between Amphiphilic Phenyleneethynylene Fluorophores and Cyclodextrins in Aqueous Media

Abstract

Binding events of cyclodextrins (CyD's) in aqueous media are important for designing and explaining the host-guest chemistry applied in sensing and controlled release systems. A water-soluble tricationic compound (3N(+)) with three branches of phenyleneethynylene fluorescent moieties and its related amphiphilic compounds (3C(-), N(0)N(+), N(+), and 2N(+)) are employed as molecular probes in the systematic characterization of the supramolecular interactions with CyD's (α, β, and γ). The strong fluorescence enhancement, combined with induced circular dichroism (CD) signals and (1)H NMR data, is evidence of 1:1 static inclusion complexes of 3N(+)/γ-CyD and 2N(+)/γ-CyD. 3N(+) presents a structural design which can form inclusion complexation with γ-CyD with one of the highest binding constants of 3.0 × 10(4). The relatively moderate fluorescence enhancement, shift of (1)H NMR signals, and weak induced CD signals indicate fast exchange complexation of β-CyD with the amphiphilic guest molecules. The interaction with α-CyD is perceived only for N(0)N(+), the only nonbranched fluorescent guest model, via its strong fluorescence enhancement. However, the lack of (1)H NMR signal splitting and the lack of induced CD signals suggest the noninclusion mode of binding between N(0)N(+) and α-CyD.

A novel phenylacetylene-indolium fluorophore for detection of cyanide by the naked eye

“…The a, b, and g-CD have been used to increase water solubility of 2. 13 The ESI; Fig. S4 † showed that 2 can completely solute in HEPES buffer at pH 7.4.…”

“…The reaction set up was simple and the purication was easy. The structure of 2 was conrmed by 1 H-NMR, 13 C-NMR, and HRMS data (see ESI; Fig. S1-S3 †).…”

“…Mp: decomposed > 250 C; 1 H-NMR (500 MHz, acetone-d6): d (ppm) 8.40 (d, J ¼ 20 Hz, 1H), 8.04 (d, J ¼ 10 Hz, 2H), 7.86-7.80 (m, 1H), 7.79-7.75 (m, 1H), (m, 2H), 7.67-7.60 (m, 5H), 7.40 (d, J ¼ 10 Hz, 2H), 6.74 (d, J ¼ 10 Hz, 2H), 4.19 (s, 3H), 3.01 (s, 6H), 1.86 (s, 6H). 13 C-NMR (500 MHz, acetone-d6): d (ppm) 183.0, 153.7, 151.5, 144.1, 142.4, 133.3, 132.0, 130.7, 130.3, 129.7, 123.6, 123.1, 115.3(2), 112.2, 96.9, 87.8, 53.2, 39.5, 25.5, 21.7. HR-ESI-MS m/z for C 29 H 29 N 2 calcd 405.2325; found 405.2322.…”

“…12 We also found that water solubility of the fluorophore containing rod-shaped phenylene-ethynylene moieties could be significantly enhanced via the formation of inclusion complexes with cyclodextrins (CyD's). 13 In this work, a novel cyanide fluorescent turn-on sensing compound 2 was designed based on phenylene-ethynylene fluorogenic rod attached to indolium group serving as a CN receptor (Scheme. 1) Compound 2 should also be able to form an inclusion complex with CyD's that lead to its application for cyanide detection in aqueous media.…”

Fabrication of cyclodextrins-procainamide supramolecular self-assembly: Shape-shifting of nanosheet into microtubular structure

“…Moreover, the presence of ␤-CD concentrations produced blue shift from 357 nm to 352 nm. The results indicated that PCA is entrapped more deeply into the ␤-CD cavity compared with ␣-CD and the formation of stable inclusion complexes (Lucas-Abellán et al, 2014;Rajendiran & Siva, 2014;Siripornnoppakhun et al, 2012;Stalin, Srinivasan, Sivakumar, & Radhakrishnan, 2014).…”