Synthesis and Characterization of Reversible Chemosensory Polymers: Modulation of Sensitivity through the Attachment of Novel Imidazole Pendants

Abstract

Three novel electron donor-acceptor conjugated polymers (P1-P3) bearing various imidazole pendants have been synthesized. Their excellent photophysical and electrochemical properties make them suitable transduction materials for chemosensing applications. Indeed, polymers P1-P3 have been found to show remarkable sensing capabilities towards H(+) and Fe(2+) in semi-aqueous solutions. Upon titration with H(+), polymers P1 and P2 showed hypsochromic shifts of their absorptions and photoluminescence (PL) maxima with enhanced fluorescence intensities. However, P3 showed diminished absorption and fluorescence intensities under similar conditions due to static quenching. The anomalous behavior of P3 compared with P1 and P2 has been clarified in terms of electronic distributions through computational analysis. Furthermore, P3 (K(SV) = 1.03×10(7)) showed a superior sensing ability towards Fe(2+) compared with P1 (K(SV) = 2.01×10(6)) and P2 (K(SV) = 4.12×10(6)) due to its improved molecular wire effect. Correspondingly, the fluorescence lifetime of P3 was greatly decreased (almost 11-fold) compared to those of polymers P1 (4.6-fold) and P2 (6.2-fold) in the presence of Fe(2+). By means of a fluorescence on-off-on approach, chemosensing reversibilities in protonation-deprotonation and metallation-demetallation have been achieved by employing triethylamine (TEA) and the disodium salt of ethylenediaminetetraacetic acid (Na(2)-EDTA)/phenanthroline, respectively, as suitable counter ligands. (1)H NMR titrations have revealed the unique behavior of P3 compared with P1 and P2. To the best of our knowledge, there have been no previous reports of Fe(2+) sensors based on single imidazole receptors conjugated to a main-chain polymer showing such a diverse sensitivity pattern depending on their attached substituents.

A Wide Bandgap Polymer Donor Composed of Benzodithiophene and Oxime-Substituted Thiophene for High-Performance Organic Solar Cells

“…1 H NMR analysis indicated that 3 contains only the Z -isomer since it is more thermodynamically stable due to the presence of a hydrogen bond between oxygen and 4-hygrogen . The overall yield of 3 starting from 1 was 70%, which may be further increased based on the higher yield (up to 92%) reported for the formation of 2 in the bromination step. , This is much higher than the overall yield of other A monomers that have been used for preparing the BDT-based D–A polymer donors, such as FC-TT (9%), TPD (54%), BDD (32%), FBTA (12%), BT (12%), and Qx (33%) (Figure S1). Moreover, the synthesis of this monomer does not require the use of hazardous reagents, such as n -butyllithium, or harsh reaction conditions, which can further reduce the synthetic complexity …”

Cationic, luminescent cyclometalated iridium(iii) complexes based on substituted 2-phenylthiazole ligands

“…Ethyl-4-methyl-2-phenylthiazole-5-carboxylate (emptzH), 31 1,10-phenanthroline-5,6-dione, 32 2,9-dimethyl-1,10-phenanthroline-5,6-dione, 33 ethyl-3,4-diaminobenzoate, 34 ethyldipyrido[3,2-a:2′,3′-c]phenazine-11-carboxylate (edppz), 35 pyridylimidazo[4,5-f ][1,10]phenanthroline ( piphen), 14 were synthesised according to the literature methods or subtle variations thereupon.…”

Solid-state NMR studies of Ziegler–Natta and metallocene catalysts

“…Besides NMR also mass spectrometry [52][53][54][55], IR and UV spectroscopy [56,57], chromatography [58,59], atomic force microscopy and scanning tunneling microscopy [60,59] are used to determine polymer microstructure.…”