Blue-green Fluorescence Research Articles

Electrochemical and optical properties of a new donor–acceptor type conjugated polymer derived from 3,4–didodecyloxythiophene

In this communication, we report the synthesis and characterization of a new donor–acceptor type conjugated polymer carrying alternate 3,4-didodecyloxythiophene and (1,3,4-oxadiazol-yl)pyridine moieties and evaluation of its optical and electrochemical properties. The polymer was synthesized through precursor polyhydrazide route. It has well defined structure, stability and it shows good solubility in common organic solvents. Optical and electrochemical properties were studied by UV-visible, fluorescence spectroscopy and cyclic voltammetric studies, respectively. It displays bluish-green fluorescence both in solution and in film state. Cyclic voltammetric studies showed that the polymer P1 possesses a HOMO energy level of −6·01 and LUMO energy level of −3·34 eV. The preliminary studies clearly reveal that the new polymer can have potential application in the fabrication of light emitting diodes. The studies on its device application are in progress.

Dinuclear Zn(II) and Hg(II) complexes of an angular dipyridyl ligand: syntheses, crystal structures, and properties

The angular polytopic dipyridyl ligand 2,6-bis(quinoline-2-carboxamido)pyridine (H2L) was prepared. Assemblies of H2L with ZnAc2 and HgAc2 resulted in two new dinuclear complexes [Zn2(L)(Ac)2] · 1.5H2O · 0.5CH3OH (1) and [Hg2(L)(Ac)2] · 5H2O · CH3OH (2) where the doubly deprotonated L2− bi-chelate as μ-kN,N′ : kN″,N″′, bridging the two metal centers (Ac = acetate). In 1, the two Zn(II) ions are also doubly bridged by two Ac ions in a μ-kO : kO′ coordination, and thus each metal center adopts a distorted tetrahedral geometry. In 2, each Ac ion is only terminal to Hg(II), in a rare distorted triangular or T-shaped coordination geometry. Free H2L, 1, and 2 emit interesting bluish-green fluorescence with strong intensities. Thermogravimetric analysis of 1 shows that the dinuclear structure of 1 is stable to 382°C.

Synthesis, Crystal Structure and Spectroscopic Property of [Cu(C20H10Cl4O2N2)]·DMF

A Schiff base ligand,N,N'-bis(3,5-dichlorosalicylaldehyde)-o-phenylenediamine,and its copper complex was synthesized.The compound was characterized by elemental analysis,FTIR,TG-DTG,single crystal X-ray diffraction,UV-Vis absorption spectroscopy,and fluorescence excitation and emission spectra.The high thermal decomposition temperature of 384 ℃ for the complex showed that it had high thermal stability.In its infrared spectrum,a strong band was observed at about 1616 cm-1.This band was due to the conjugated C N stretching vibration,and was shifted to higher frequency compared with the free ligand of 3,5-dichlorosalicylaldehyde and o-phenylenediamine.The new band at 530 cm-1 was assigned to Cu—O stretching vibration.The crystal of the copper(Ⅱ) complex belongs to monoclinic system with space group,P2(1)/n,a = 0.81316(8) nm,b = 1.53101(18) nm,c = 1.87819(19) nm,β = 92.4530(10) °,Z = 4,the final R1 = 0.058,and ωR2 = 0.148.The central copper ion of the complex coordinated with the two O and two N of the Schiff base to form a five-membered ring and two six-membered rings,which constituted a fourcoordinated planar conformation.The complex's UV absorption bands were at about 268,310 and 435 nm,where the absorption band at about 435 nm can be assigned to the intrinsic absorption of C N.Its fluorescence excitation is in the range of 360 ～ 480 nm,and its DMF solution emitted intensive blue-green fluorescence at the peak wavelength of 507 nm.Its optical gap was about 2.59 eV,which was determined by the intrinsic absorption band edge of the complex in DMF solution.

First Report of Bacterial Blight of Brussels sprouts (Brassica oleracea var. gemmifera) Caused by Pseudomonas cannabina pv. alisalensis in California.

Greenhouse-grown Brussels sprouts (Brassica oleracea L. var. gemmifera) transplants from Monterey County, California showed symptoms in 2006 of a previously undescribed disease. Initial symptoms consisted of small (1 to 2 mm in diameter), angular, water-soaked flecks, some of which were surrounded by chlorotic haloes. These flecks coalesced into large, irregularly shaped, gray brown lesions as large as 10 mm. Lesions were visible from both adaxial and abaxial leaf surfaces and generally retained chlorotic borders. This disease resulted in decreased quality and reduced marketability of the transplants. Gram-negative, blue-green fluorescing bacteria were consistently isolated from lesions on King's medium B agar. Ten isolates were selected and used in further studies. Isolates were levan positive, oxidase negative, and arginine dihydrolase negative. Isolates did not rot potato slices but induced a hypersensitive reaction in tobacco (Nicotiana tabacum L. cv. Samsun). These data indicated that the bacteria belonged to Lelliot's LOPAT group 1 (2). Repetitive extragenic palindromic sequence (REP)-PCR using the BOXA1R primer resulted in identical DNA fragment banding patterns for the Brussels sprouts isolates and the pathotype of Pseudomonas cannabina pv. alisalensis (formerly P. syringae pv. alisalensis). Like P. cannabina pv. alisalensis, the isolates from Brussels sprouts were sensitive to bacteriophage PBS1 (1). All 10 isolates were used in two independent pathogenicity experiments. Inoculum for pathogenicity studies was prepared by growing the bacteria on nutrient agar for 48 h (27°C), suspending the bacteria in 0.01 M phosphate buffer (pH 7.0), and adjusting each suspension to 0.6 OD at 600 nm (approximately 108 CFU/ml). In each experiment, six Brussels sprouts plants were inoculated for each isolate by spraying until runoff or by swabbing a suspension of the appropriate bacterial isolate to which Carborundum had been added. Additionally, four Brussels sprouts isolates were used to spray inoculate six broccoli raab (Brassica rapa subsp. rapa) plants. Positive control plants were inoculated with the pathotype of P. cannabina pv. alisalensis, and the negative control plants were inoculated with sterile buffer or sterile buffer with Carborundum. Inoculated plants were placed in a mist chamber for 48 h and then in a greenhouse (20 to 25°C). After 5 to 7 days, foliar symptoms similar to symptoms observed on the original diseased Brussels sprouts plants developed on all inoculated plants, including the positive control plants inoculated with P. cannabina pv. alisalensis. Negative control plants remained symptomless. In each experiment, bacteria reisolated from symptomatic tissue were identical to the bacteria used to inoculate the plants and to P. cannabina pv. alisalensis for LOPAT reactions, REP-PCR DNA fragment banding pattern, and sensitivity to phage PBS1. To our knowledge, this is the first report of P. cannabina pv. alisalensis causing bacterial blight of Brussels sprouts.

Photoactive metallic (Al 3+, Zn 2+, Eu 3+, Tb 3+, Er 3+, Nd 3+) mesoporous hybrid materials by functionalized 8-hydroxyquinolinate linkage covalently bonded SBA-15

A kind of monomer HQSi has been achieved and its functionalised SBA-15 hybrid materials have been synthesized. Luminescent hybrid mesoporous materials consisting of different metal ions (Al 3+, Zn 2+, Eu 3+, Tb, Er 3+, Nd 3+) complex covalently bonded to the mesoporous materials network have been obtained via this sol–gel approach. The resulting materials were characterized by powder X-ray diffraction, N 2 adsorption/desorption, and thermogravimetric analysis. Luminescence spectra of these lanthanide-complex functionalized materials were also recorded. While irradiated with a UV lamp, the finally materials show blue-green color fluorescence. The good luminescent performances enable these luminescent hybrid mesoporous materials to have potential applications in the field of photoluminescence.

Fluorescence Polymer Incorporating Triazole and Benzo[2,1,3]thiadiazole Moieties for Ni²+ Detection

Conjugated polymer could be obtained by the polymerization of 4,7-diethynylbenzo[2,1,3]thiadiazole (M-1) with 1,4-diazidobenzene (M-2) via click reaction. The polymer shows strong blue-green fluorescence due to the extended π-electronic structure in the main chain backbone. The responsive optical properties of the polymer on various transition metal ions were investigated by fluorescence spectroscopy. Compared with other transition metal cations, such as Co²+, Hg²+, Ag+, Cd²+, Cu²+ and Zn²+, Ni²+ showed the most pronounced fluorescence response in the presence of the conjugated polymer. The results indicate this kind of polymer with benzo[2,1,3]thiadiazole and triazole units can be used as a selective fluorescence sensor for Ni²+ detection.

Improved Discrimination between Monocotyledonous and Dicotyledonous Plants for Weed Control Based on the Blue-Green Region of Ultraviolet-Induced Fluorescence Spectra

Precision weeding by spot spraying in real time requires sensors to discriminate between weeds and crop without contact. Among the optical based solutions, the ultraviolet (UV) induced fluorescence of the plants appears as a promising alternative. In a first paper, the feasibility of discriminating between corn hybrids, monocotyledonous, and dicotyledonous weeds was demonstrated on the basis of the complete spectra. Some considerations about the different sources of fluorescence oriented the focus to the blue-green fluorescence (BGF) part, ignoring the chlorophyll fluorescence that is inherently more variable in time. This paper investigates the potential of performing weed/crop discrimination on the basis of several large spectral bands in the BGF area. A partial least squares discriminant analysis (PLS-DA) was performed on a set of 1908 spectra of corn and weed plants over 3 years and various growing conditions. The discrimination between monocotyledonous and dicotyledonous plants based on the blue-green fluorescence yielded robust models (classification error between 1.3 and 4.6% for between-year validation). On the basis of the analysis of the PLS-DA model, two large bands were chosen in the blue-green fluorescence zone (400-425 nm and 425-490 nm). A linear discriminant analysis based on the signal from these two bands also provided very robust inter-year results (classification error from 1.5% to 5.2%). The same selection process was applied to discriminate between monocotyledonous weeds and maize but yielded no robust models (up to 50% inter-year error). Further work will be required to solve this problem and provide a complete UV fluorescence based sensor for weed-maize discrimination.

Optical characterization of a new donor–acceptor type conjugated polymer derived from 3,4-diphenylthiophene

A new donor–acceptor type poly{2-(3,4-didecyloxythiophen-2-yl)-5-[3,4-diphenyl-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-1,3,4-oxadiazole} (P1) has been designed and synthesized starting from thiodiglycolic acid, 1,2-diphenylethane-1,2-dione, and diethyl oxalate through multi-step reactions using precursor polyhydrazide route. The charge-transporting and linear optical property of the polymer has been investigated by cyclic voltammetric, UV–visible, and fluorescence emission spectroscopic studies. The UV–visible absorption spectrum of polymer in thin film form showed maxima at 420 nm. The polymer displayed bluish-green fluorescence both in solution and thin film form. The optical band gap is determined to be 2.27 eV. Third-order nonlinear optical property of the new polymer has been investigated at 532 nm using single beam Z-scan and degenerate four wave mixing (DFWM) techniques with nanosecond laser pulses. The absorptive nonlinearity observed for the polymer P1 is of optical limiting type, which arises due to an “effective” three-photon absorption (3PA) process. The third-order nonlinear optical susceptibility (χ(3)) of the polymer is found to be 0.831 × 10–12 esu. Both linear and nonlinear optical studies revealed that the new polymer (P1) is a promising material for applications in photonic devices.

Imaging of multi-color fluorescence emission from leaf tissues

Multi-color fluorescence emission from leaf tissues is presented as a powerful reporter on plant biochemistry and physiology that can be applied both at macro- and micro-scales. The blue-green fluorescence emission is typically excited by ultraviolet (UV) excitation. However, this approach cannot be applied in investigating intact leaf interior because the UV photons are largely absorbed in the epidermis of the leaf surface. This methodological barrier is eliminated by replacing the UV photon excitation by excitation with two infra-red photons of the same total energy. We demonstrate this approach by using two-photon excitation for microscopy of Arabidopsis thaliana leaves infected by pathogenic bacterium Pseudomonas syringae. The leaf structures are visualized by red chlorophyll fluorescence emission reconstructed in 3-D images while the bacteria are detected by the green emission of engineered fluorescence protein.

Synthesis and characterization of a new NLO-active donor–acceptor-type conjugated polymer derived from 3,4-diphenylthiophene

A new donor–acceptor-type conjugated polymer (P1) carrying 3,4-diphenylthiophene, 2,5-dihexyloxybenzene, and 1,3,4-oxadiazole units was synthesized through multistep reactions. The polymer was prepared using a polyhydrazide precursor route. The polymer has a well-defined structure and exhibits good thermal stability, with a decomposition onset temperature in nitrogen of 300 °C. Cyclic voltammetry experiments revealed that the polymer has low-lying LUMO (−3.68 eV) and high-lying HOMO (−5.78 eV) energy levels. The electrochemical band gap was found to be 2.10 eV. The UV-visible absorption spectrum of the polymer presented a maximum at 373 nm, and it displayed bluish-green fluorescence in dilute chloroform solution. The nonlinear optical properties of the new polymer were investigated at 532 nm using the Z-scan technique with nanosecond laser pulses. The polymer exhibited strong optical limiting behavior due to excited state absorption, which was phenomenologically similar to a three-photon absorption (3PA) process. The 3PA coefficient γ was found to be 7 × 10−22 m3/W2. The studies show that the new polymer (P1) is a promising material for developing efficient photonic devices.

Cellulose Derivatives Carrying Triphenylamine (TPA) Moieties: Synthesis and Electro‐Optical Properties

A novel ethyl cellulose derivative [poly(1)] that carries triphenylamine moieties is synthesized with a moderate number-average molecular weight up to 78,200 in 85% yield by the reaction of 4-(diphenylamino)benzoic acid with the residual hydroxy group of ethyl cellulose. Poly(1) is soluble in common organic solvents including toluene, CHCl3, CH2Cl2, and tetrahydrofuran while insoluble in hexane, diethyl ether, and methanol. The polymer emits blue-green fluorescence with quantum yields up to 65% in CHCl3 and displays unique solvatochromism. The cyclic voltammograms of poly(1) indicate that the polymer carrying TPA moieties is electrochemically redox active. The onset temperature of weight loss of the poly(1) is about 177 degrees C according to thermogravimetric analysis in air.

Scientific and technical challenges in remote sensing of plant canopy reflectance and fluorescence

State-of-the-art optical remote sensing of vegetation canopies is reviewed here to stimulate support from laboratory and field plant research. This overview of recent satellite spectral sensors and the methods used to retrieve remotely quantitative biophysical and biochemical characteristics of vegetation canopies shows that there have been substantial advances in optical remote sensing over the past few decades. Nevertheless, adaptation and transfer of currently available fluorometric methods aboard air- and space-borne platforms can help to eliminate errors and uncertainties in recent remote sensing data interpretation. With this perspective, red and blue-green fluorescence emission as measured in the laboratory and field is reviewed. Remotely sensed plant fluorescence signals have the potential to facilitate a better understanding of vegetation photosynthetic dynamics and primary production on a large scale. The review summarizes several scientific challenges that still need to be resolved to achieve operational fluorescence based remote sensing approaches.

Synthesis and properties of chiral helical polymers based on optically active polybinaphthyls

The chiral polymer P-1 was synthesized by the polymerization of ( R)-6,6′-dibutyl-3,3′-diiodo-2,2′-bisoctoxy-1,1′-binaphthyl ( R-M-1 ) with 5,5′-divinyl-2,2′-bipyridine ( M-1) via Pd-catalyzed Heck reaction. P-2 and P-2′ were prepared by Wittig–Horner reaction of ( R)-6,6′-dibutyl-2,2′-bisoctoxy-1,1′-binaphthyl-3,3′-dicarbaldehyde ( R-M-2 ) with 5,5′-bis (diethylphosphonomethyl)-2,2′-bipyridine ( M-2) in the presence of EtONa or NaH, respectively. P-3 was synthesized by Wittig–Horner reaction of ( R)-6,6′-di(4-trifluoromethylphenyl)-2,2′-bisoctoxy-1,1′-binaphthyl-3,3′-dicarbaldehyde ( R-M-3 ) with M-2 using NaH as a base. The four polymers have strong blue-green fluorescence due to the extended π-electronic structure between the chiral model compounds ( R)-6,6′-dibutyl-/di(4-trifluoromethylphenyl)-2,2′-bisoctoxy-1,1′-binaphthyl ( R-1 or R-2 ) and the conjugated linker 2,2′-bipyridyl group via vinylene bridge. Both monomers and polymers were analyzed by NMR, MS, FT-IR, UV–vis spectroscopy, DSC–TGA, fluorescence spectroscopy, GPC and circular dichroism (CD) spectroscopy. Based on the great differences of specific rotation values and CD spectra, P-1 and P-2 may adopt a zigzag chain configuration, while P-2′ and P-3 may adopt a helical configuration. The responsive optical properties of the two chiral helical polymers P-2′ and P-3 on transition metal ions were investigated by fluorescence, UV–vis and CD spectra. The results show that Ag + and Ni 2+ lead to nearly complete fluorescence quenching of P-2′ and P-3, Cu 2+ and Fe 2+ can cause obvious fluorescence quenching, but Zn 2+ and Cd 2+ can only produce slight fluorescence quenching. Ag +, Ni 2+, Cu 2+ and Fe 2+ can also lead to the obvious changes of UV–vis spectra of P-2′ and P-3. On the contrary, Zn 2+ and Cd 2+ cause little changes. Most importantly, the CD intensities and wavelengths of the chiral helical polymers P-2′ and P-3 exhibit the pronounced changes upon addition of Ag + and Ni 2+.

The synthesis and characterization of novel dipolar fluorescent materials based on a quinoxaline core

A series of dipolar quinoxaline derivatives with quinoxaline as core which carry pendant carbazole or triphenylamine moieties were synthesized and fully characterized. As expected, the compounds display bipolar character and can be explored as potential emissive and electron-transport materials as organic light-emitting diodes. Fluorescence spectra showed that the compounds exhibit excellent blue-green fluorescence.

Synthesis and nonlinear optical characterization of new poly{2,2′-(3,4-didodecyloxythiophene-2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole

A new donor–acceptor type poly{2,2′-(3,4-didodecyloxythiophene-2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]} ( P) was synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge-transporting property of the copolymer was investigated by UV–vis, fluorescence emission spectroscopic and cyclic voltammetric studies. The copolymer shows UV absorption maxima at 375 nm and displays bluish-green fluorescence in DMF solution. Its electrochemical band gap was determined to be 2.07 eV. The nonlinear optical (NLO) properties of the copolymer was investigated at 532 nm using single beam Z-scan and degenerate four-wave mixing (DFWM) techniques with nanosecond laser pulses. The copolymer exhibits strong optical limiting behavior due to effective three-photon absorption (3PA). Values of the effective 3PA coefficient ( γ), third-order nonlinear susceptibility ( χ (3)) and figure of merit ( F) have been calculated.

Third-order nonlinear optical susceptibilities of new copolymers containing alternate 3,4-dialkoxythiophene and (1,3,4-oxadiazolyl)pyridine moieties

A new series of conjugated copolymers ( P1– P3) consisting of alternate 3,4-dialkoxythiophene and (1,3,4-oxadiazolyl)pyridine moieties have been synthesized using the precursor polyhydrazide route. They have been characterized by FTIR, 1H NMR spectral and elemental analyses. These copolymers possess well defined structure and exhibit good thermal stability with the onset decomposition temperature in nitrogen at around 300 °C. Their molecular weights were determined by gel permeation chromatography (GPC). The optical and charge-transporting properties of the copolymers were investigated by UV–visible spectroscopy, fluorescence emission spectroscopy and cyclic voltammetry. Their UV–visible absorption spectra showed a λ max at around 342 nm and displayed bluish-green fluorescence in solution state. The band gaps were found to be at about 2.55 eV for all the copolymers. The third-order nonlinear optical properties (NLO) of these copolymers were studied by Z-scan technique. The measurements were performed at 532 nm with 7 ns laser pulses using a Nd:YAG laser in solution form. The real part of χ (3) were estimated to be −0.881 × 10 −12, −0.901 × 10 −12 and −1.030 × 10 −12 esu for P1, P2 and P3 respectively. The imaginary part of χ (3) for the copolymers P1, P2 and P3 were determined to be 0.192 × 10 −12, 0.253 × 10 −12 and 0.272 × 10 −12 esu respectively. The copolymers exhibit strong reverse saturable absorption and good optical limiting behaviour at 532 nm.

新型双光子吸收生色分子的电化学、热性能和光物理性质

Electrochemical, thermal, and photophysical properties of novel two- (BPODPA), four- (BBPOPA), and six-branch (TBPOA) triphenylamine chromophores are studied. The decomposition temperature of chromophores reaches 373-412 C. The electrochemical properties is explored by cyclic voltammetry. The ionization potential of chromophores is in the range of 5.14-5.18 eV. Excitation at 400 nm reveals emission peaks at 483-487 nm and the fluorescence quantum yields are 0.73-0.75 in CH2Cl2 Two-photon absorption (TPA) properties of chromophores are measured by nonlinear transmission method. The maximum TPA cross-section values are measured at 758 nm to be 20369 GM (1 GM=10^{-50} cm4s/photon) for TBPOA, 7024 GM for BBPOPA, and 1227 GM for BPODPA, respectively. When pumped with 800-nm laser irradiation, chromophores show strong two-photon excited blue-green fluorescence at 502-518 nm. These results provide a basis for understanding the electronic and optical properties of the conjugated multi-branch chromophore in terms of the underlying molecular and electronic structures.

Fluorescent chemosensor based on the conjugated polymer incorporating 2,2′‐bipyridyl moiety for transition metal ions

AbstractA fluorescent conjugated polymer was synthesized by the polymerization of 1,4‐dibromo‐2,3‐bisbutoxynaphthalene (M‐2) with 5,5′‐divinyl‐2,2′‐bipyridine (M‐3) via Heck reaction. The conjugated polymer shows strong blue–green fluorescence because of the extended π‐electronic structure between the repeating unit 2,3‐bisbutoxynaphthyl group and the conjugated linker 2,2′‐bipyridyl (bpy = 2,2′‐bipyridine) moiety via vinylene bridge. The responsive properties of the conjugated polymer on transition metal ions were investigated by fluorescent and UV–vis spectra. The results show that Cu2+ and Ni2+ can form nonradiative metal‐to‐ligand charge‐transfer complexes with the polymer, whereas, Zn2+ and Cd2+ do not produce the pronounced differences from the polymer fluorescence and UV–vis spectra. The fluorescent quenching can probably be attributed to the intramolecular photoinduced electron transfer (PET) or photoinduced charge transfer (PCT). The results can also suggest that 2,2′‐bipyridyl moiety in the main chain backbone of the conjugated polymer can act as the recognition site of a special fluorescent chemosensor for sensitive detection of transition metal ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

High-purity white light from a simple single dopant host-guest white organic light-emitting diode architecture

White light with good color properties (color rendering index=82–87) is generated in a simple organic light-emitting diode comprising an emissive layer, composed of an undoped tris(4-methyl-8-quinolinato)aluminum (Almq3) sublayer and region doped with an orange-red phosphorescent dopant, bis(2-phenyl-1-quinoline)iridium acetylacetonate (Ir(pq)2acac). Electron-hole recombination in a thin spacing Almq3 layer results in blue-green fluorescence, while the formed triplet excitons diffuse to the doped region and are harvested by the dopant to emit orange-red phosphorescence. The combination of blue-green and orange lights results in warm white light. This approach takes advantage of efficient migration of triplet excitons while being less demanding in terms of fabrication and color matching.

Synthesis and Fluorescent Properties of a Chiral Conjugated Polymer Based on (S)-2,2′-Binaphtho-20-crown-6

Abstract Linear conjugated polymer was obtained by the polymerization of 2,3-dibutoxy-1,4-diethynylnaphthalene (M-1) and (S)-5,5′-dibromo-6,6′-dibutyl-2,2′-binaphtho-20-crown-6 (S-M-2) via Pd-catalyzed Sonogashira reaction. The conjugated polymer shows strong green-blue fluorescence due to the extended π-electronic structure between the chiral repeating unit (S)-6,6′-dibutyl-2,2′-binaphtho-20-crown-6 and the conjugated linker 2,3-dibutoxynaphthyl group via acetylene bridge. The responsive properties of the chiral polymer on K+, Pb2+, Hg2+, and AsIII were investigated by fluorescent spectra. The results show that Hg2+ and AsIII can cause effective fluorescent quenching of the polymer, whereas, K+ and Pb2+ do not produce obvious changes in the polymer fluorescence. The obvious fluorescent influence shows that the 2,2′-binaphtho-20-crown-6 moiety plays an important role in fluorescent recognition for Hg2+ and AsIII due to the effective photoinduced electron transfer (PET) and charge transfer (PCT) between the conjugated polymer backbone and receptor species.