A Fluorescent Chemosensor for Transition‐Metal Ions Based on Optically Active Polybinaphthyl and 2,2′‐Bipyridine

Abstract

The linear conjugated polymer based on the 5,5′‐positions of chiral 1,1′‐binaphthyl shows strong green‐blue fluorescence with high fluorescence quantum efficiency due to the extended π‐electronic structure between the chiral repeating unit and the 2,2′‐bipyridyl conjugated linker unit. Cu2+ and Ni2+ can form non‐radiative metal‐to‐ligand charge‐transfer complexes with the polymer, and Co2+, Mn2+, Cd2+, Zn2+, Fe2+ can cause effective fluorescent quenching, which can be attributed to an energy transfer from the π‐conjugated chiral polymer to the metal complexes. A better understanding of energy‐transfer processes in the polymers can provide information for the design of more sensitive materials.magnified image

Synthesis and Fluorescent Properties of Chiral Polymer Complexes Incorporating Bipyridine and Eu(III) or Gd(III)

“…The 1 L a and 1 B b band intensities and positions of the chiral polymer and polymer complexes are greatly different from that of the chiral repeating unit R-1. 16,27 1 L a band of R-1 appears at 256 nm while P-1, P-2 and P-3 do not show any 1 L a bands in their CD spectra. Moreover, CD intensity of R-1 is much stronger than those of the chiral polymer P-1 and polymer complexes P-2, P-3.…”

“…P-2 and P-3 can be attributed to the effective π-π* conjugated segment of the linker unit R-1 and 2,2'-bipyridyl group via vinylene bridge along the main-chain backbone and β-diketonate anion TTA in the RE(III)-containing polymer complex moiety. 16,27,49 Table 1 Optical properties of the repeating units and P-1, P-2 and P-3 Fluorescent spectra of R-1, M-2, P-1, P-2 and P-3 in CH 2 Cl 2 are showed in Figure 3. R-1 and M-2 do not show fluorescence in the visible light region.…”

“…[8][9][10][11][12][13] According to the reported literature, so far there have been very few reports on the halogenation of BI-NOL at the 5,5'-positions except that our group reported the facile synthesis of optically active 5,5'-dibromo-6,6'-dialkyl/diaryl-1,1'-bi (2-naphthol), and Pirkle described the synthesis and chiral resolution of racemic 5,5'-dibromo-6,6',7,7'-tetramethyl-1,1'-bi(2-napthol). [14][15][16][17][18] Based on our current study, (R)-BINOL can be specifically brominated at 5,5'-positions under mild conditions to afford a pure product in an excellent yield when 6,6'positions are occupied by 4-trifluoromethylphenyl group. 17 As known, lanthanide complexes, especially those of Eu(III) and Tb(III), have pure monochromic characteristic emission, extremely long photoluminescence life-time, chemical environmental stability, and potentially high internal quantum efficiency.…”

A new Cu2+-induced color reaction of a rhodamine derivative N-(3-carboxy)acryloyl rhodamine B hydrazide

“…stoichiometery, the color-on reaction of CARB with Cu 2+ may be explained by the route depicted in Scheme 2: the carboxyl and hydrazide groups in CARB produce a cooperation effect, leading to the formation of a 1:2 complex. The two Cu 2+ ions in the complex may play different roles: one induces the opening of the spirocyclic structure and the other quenches the fluorescence of the xanthene moiety [34][35][36]. It is noted that the curve in Figure 6(b) appears somewhat in an S-shape, suggesting that the two Cu 2+ ions might also have a cooperation effect in the reaction.…”

NITROAROMATIC COMPOUND SENSING APPLICATION OF HEXA-ARMED DANSYL END-CAPPED POLY(epsilon-CAPROLACTONE) STAR POLYMER WITH PHOSPHAZENE CORE

“…Therefore, fluorescence chemosensors were used for the detection of various analytes such as cations, anions, nitroaromatics, biological entities, etc. [15][16][17][18]. Dansyl-based polymers have been employed as fluorescent probes due to strong fluorescence and relatively long emission wavelength of dansyl unit in the visible region as well as its structural flexibility for derivatization [18][19][20][21] [23].…”