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1.
The cyclic amphiphilic polymers with azobenzene in main chain, cyclic azobenzene tetraethylene glycol polystyrene (cyclic‐Azo‐TEG‐PS) with different molecular weights, were successfully synthesized by combining atom transfer radical polymerization (ATRP) and Cu (I)‐catalyzed azide/alkyne cycloaddition (CuAAC). Gel permeation chromatography (GPC), proton nuclear resonance (1H NMR), Fourier transform‐infrared (FT‐IR), and matrix‐assisted laser desorption/ionization time of flight (MALDI‐TOF) mass spectrometry were used to prove the complete conversion from linear polymers to cyclic ones. The thermal properties and photoisomerization behaviors of obtained cyclic polymers have been investigated by comparison with the linear analogues. The cyclic polymer displayed a higher glass transition temperature compared with the linear one, measured by differential scanning calorimetry (DSC). It was found that the trans‐to‐cis and cis‐to‐trans isomerization of cyclic polymers was both slower than that of their respective linear counterparts upon irradiation by UV/visible light. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1834–1841  相似文献   

2.
Three chiral polymers P‐1 , P‐2 , and P‐3 could be obtained by the polymerization of (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2, 2′‐binaphthol (R‐M‐1) , (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2,2′‐bisoctoxy‐1,1′‐binaphthyl ( R‐M‐2 ), and (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2,2′‐bis (diethylaminoethoxy)‐1,1′‐binaphthyl ( R‐M‐3 ) with 4,7‐diethynyl‐benzo[2,1,3]‐thiadiazole ( M‐1) via Pd‐catalyzed Sonogashira reaction, respectively. P‐1 , P‐2 , and P‐3 can show pale red, blue–green, and orange fluorescence. The responsive optical properties of these polymers on various metal ions were investigated by fluorescence spectra. Compared with other cations, such as Co2+, Ni2+, Ag+, Cd2+, Cu2+, and Zn2+, Hg2+ can exhibit the most pronounced fluorescence response of these polymers. P‐1 and P‐2 show obvious fluorescence quenching effect upon addition of Hg2+, on the contrary, P‐3 shows fluorescence enhancement. Three polymer‐based fluorescent sensors also show excellent fluorescence response for Hg2+ detection without interference from other metal ions. The results indicate that these kinds of tunable chiral polybinaphthyls can be used as fluorescence sensors for Hg2+ detection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 997–1006, 2010  相似文献   

3.
IntroductionThepotentialforuseoftwo photonabsorbingmoleculesinapplicationsrangingfromopticallimiting1 3tothreedimensional (3D)fluorescencemicroscopy4 and 3Dmicrofabricationandopticaldatastorage5,6 hasstimulatedresearchonthedesign ,synthesis ,andcharacterizationofnewmoleculeswithlargetwo photonabsorptivities .7,8Thetwo photonabsorption (2PA)processconsideredherein volvesthesimultaneousabsorptionoftwophotons ,eitherdegeneratingornondegenerating ,atwavelengthswellbe yondthelinearabsorptionspectr…  相似文献   

4.
A complex of Eu3+, acrylic acid (AA), and 1, 10‐phenanthroline (Phen) was synthesized. The structure and fluorescence of Eu(AA)3Phen was characterized with elemental analysis, FTIR, 1H NMR, and fluorescence spectroscopy. A novel copolymer containing rare earth complex, poly(PEGMA‐co‐NIPAm‐co‐Eu(AA)3Phen) (PPNEu), was prepared by free radical copolymerization in methanol with azodiisobutyronitrile as initiator. 1H NMR, fluorescence spectroscopy, UV‐vis spectroscopy, and TEM were used to characterize this copolymer. The interaction of PPNEu with deoxyribonucleic acid (DNA) was studied by fluorescence spectroscopy, UV‐vis spectroscopy and agarose gel electrophoresis. The results of fluorescence, UV‐vis absorption, and agarose electrophoresis indicated that the PPNEu could interact with DNA in an electrostatic bonding mode. The TEM observation showed that the PPNEu could form spherical micelles in water solution small than 100 nm; the efficient complexation of PPNEu with DNA occurred. These results suggested the potential of the PPNEu as gene detective reagent and gene delivery carrier. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010  相似文献   

5.
IntroductionSubstitutedstilbeneshavesignificantpotentialapplica tionssuchasfluorescencemicroscopy ,two photonphotody namictherapy ,opticalpowerlimiting ,three dimensionalstorage,andthree dimensionalmicrofabrication .1 4 Thesedyeshavestrongtendencyofintra molecularchargetransferundertheexcitedstate.Asaresult,theyusuallyexhibitlargetwo photonabsorption (TPA) ,inthemeanwhileemitstrongup convertedfluorescence .Ontheotherhand ,theirsolutionsgenerallydisplaylineartransmissionof >90 %atwavelengthof…  相似文献   

6.
A new two‐photon material, 3E,6E‐bis(2‐pyrid‐4′‐ylvinyl)dibenzothiophene (BPVDBT), has been firstly synthesized by an efficient Pd‐catalyzed Heck coupling route. The single‐ and two‐photon fluorescence, quantum yields, lifetimes, solvent effects of the chromophore were studied in detail and the compound exhibited solvent‐sensitivity. The fluorescence intensity (Iout) and input excitation intensity (Iin) can fit in well with the quadratic parabolas, which indicates that the up‐converted fluorescence was induced by the two‐photon absorption (TPA). TPA cross‐section of BPVDBT has been measured using the two‐photon‐induced fluorescence method, whose value is 14.24×10?50 cm4·s·photon?1·molecule?1 at 750 nm. The experimental results confirm that BPVDBT is a good two‐photon absorbing chromophore with an A‐π‐A type.  相似文献   

7.
2‐(2‐Hydroxy‐phenyl)‐4(3H)‐quinazolinone (HPQ), an organic fluorescent material that exhibits fluorescence by the excited‐state intramolecular proton‐transfer (ESIPT) mechanism, forms two different polymorphs in tetrahydrofuran. The conformational twist between the phenyl and quinazolinone rings of HPQ leads to different molecular packing in the solid state, giving structures that show solid‐state fluorescence at 497 and 511 nm. HPQ also shows intense fluorescence in dimethyl formamide (DMF) solution and selectively detects Zn2+ and Cd2+ ions at micromolar concentrations in DMF. Importantly, HPQ not only detects Zn2+ and Cd2+ ions selectively, but it also distinguishes between the metal ions with a fluorescence λmax that is blue‐shifted from 497 to 420 and 426 nm for Zn2+ and Cd2+ ions, respectively. Hence, tunable solid‐state fluorescence and selective metal‐ion‐sensor properties were demonstrated in a single organic material.  相似文献   

8.
This contribution presents the synthesis and properties of four thiophene‐containing poly(‐p‐arylene‐ethynylene)/poly(‐p‐arylene‐vinylene)s, PIa‐b and PIIa‐b , whose repeating units (RU) consist either of 1:2 or 2:2 triple bond/double bond ratio, and which bear linear alkoxy side chains not longer than octyloxy and branched 2‐ethylhexyloxy. PIa‐b and PIIa‐b exhibit similar absorption and emission behaviour in dilute solution (λa = 483–486 nm, λe = 540 nm) as well as in solid state (λa = 500, 530 nm, λe = 560 nm), whereby slightly higher fluorescence quantum yields (Φf) were obtained for PI than for PII systems, as a result of higher number of thiophene units within the RU of PII . An enhancement of the Φf‐value from 0% to 3% is obtained after replacing linear octadecyloxy in PIIc‐e by bulky branched 2‐ethylhexyloxy in PIIa‐b . Nonoptimized solar cells of configuration ITO/PEDOT:PSS/polymer: PCBM (1:3 weight ratio)/LiF/Al show open circuit voltages as high as 900 mV for PIa‐b and 800 mV for PIIa‐b . Reducing the size of the side chain from R = 2‐ethylhexyl in PIa to R = methyl in PIb leads to a significant increase of the short circuit current, I SC, from ca. 2.5 mA to ca. 3.7 mA and consequently to an enhancement of the energy conversion efficiency, ηAM1.5, from ca. 1.2% to ca. 1.7%. This is due to an extended donor‐acceptor interfacial area, as evidenced by AFM topology pictures showing smaller nanoscale clusters size in PIb than in PIa active layer. The same change led to minimal effect in PII systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1619–1631, 2007  相似文献   

9.
E,E-1,4-Bis(4'-N,N-diphenylaminostyryl)-2,5-dimethoxybenzene (DPAMOB) has been synthesized by a simple and effective solid phase Wittig reaction and characterized by 1^H NMR spectra and elemental analysis, Linear absorption, single-photon induced fluorescence and two-photon induced fluorescence spectra were experimentally studied. The new dye has a large two-photon absorption (TPA) cross-section of σr= 1007,2 GM [1 GM= 1 × 10^-50 cm^4·s/(photon molecule)] at 800 nm measured by the two-photon induced fluorescence method. The experimental results confirm that DPAMOB is a good TPA chromophore and can successfully initiate two-photon photopolymerization of ethoxylated trimethylolpropane triacrylate esters (SR454). Finally, a microstructure has been fabricated by use of DPAMOB as initiator.  相似文献   

10.
At different temperatures, the interactions between imidacloprid (IMI) and bovine serum albumin (BSA) were investigated with a fluorescence quenching spectrum, a synchronous fluorescence spectrum, a three-dimensional fluorescence spectrum and an ultraviolet-visible spectrum. The average values of bonding constants (KLB: 3.424 × 10^4 L,mol^-1), thermodynamic parameters (△H: 5.188 kJ,mol^-1, △G^(○—):-26.36 kJ,mol^-1, △S: 103.9 J,K^-1,mol^-1) and the numbers of bonding sites (n: 1.156) could be obtained through Stern-Volmer, Lineweaver-Burk and ther- modynamic equations. It was shown that the fluorescence of BSA could be quenched for its reactions with IMI to form a certain kind of new compound. The quenching belonged to a static fluorescence quenching, with a non-radiation energy transfer happening within a single molecule. The thermodynamic parameters agree with △H〉 0, △S〉0 and△G^(○-)〈0, suggesting that the binding power between IMI and BSA should be mainly a hydrophobic interaction.  相似文献   

11.
手性高分子P–1由(R)-5,5′-二溴-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘(R–M–1)和5,5′-二乙烯基-2,2′-联吡啶(M–2)通过Pd催化的Heck偶合反应合成得到,高分子配合物P-2和P-3由高分子P-1与Eu(TTA)3·2H2O和Gd(TTA)3·2H2O (TTA– = 2-噻吩甲酰三氟丙酮)反应生成。手性高分子P-1能发射强的蓝色荧光,这是由于手性重复单元(R)-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘和单元2,2′-联吡啶通过亚乙烯基桥连形成共轭高分子结构造成的。在不同的激发波长激发下,含Eu(III)的高分子配合物P–2不仅显示高分子荧光,还可显示Eu(III) (5D0→7F2)特征荧光。含Gd(III)的高分子配合物P–3仅发射高分子荧光。基于高分子及含RE(III)的高分子配合物的荧光性质研究发现,共轭高分子并没有把能量转移到Eu(III)或Gd(III) 配合物部分,只发射它自身的荧光,含Eu(III)的高分子配合物P–2发射Eu(III) (5D0→7F2)特征荧光能量主要来源于配阴离子TTA–。  相似文献   

12.
Copolymerization of propargylether having antipyrine group (PT) and N‐(tert‐butoxycarbonyl)‐l ‐valine‐N‐propargylamide (LA) was conducted with (nbd)Rh+[η6‐C6H5B?(C6H5)3] as a catalyst to obtain novel antipyrine‐functionalized chiral copolymer. The controllable secondary structure of the copolymers by different unit ratio or solvent environment led to a controlled fluorescence of the side‐chain antipyrine. Poly(LA88co‐PT12) exhibited a large specific rotation and a circular dichroism (CD) signal, while it emitted very stronger fluorescence. From CD and ultraviolet–visible spectra, the regular structure of poly(LA88co‐PT12) was destroyed, and the random coil was formed with temperature increase. The helical conformation of poly(LA75co‐PT25) disappeared by the addition of MeOH to CHCl3 solution, while the fluorescence signal also became weaker than in CHCl3 solution. It is suggested that the copolymer conformation much influenced the performance of chromophores. In the present study, the helix conformation could induce fluorescence enhancement. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
《中国化学》2018,36(1):25-30
Multimodal imaging techniques have been demonstrated to be greatly advantageous in achieving accurate diagnosis and gained increasing attention in recent decades. Herein, we present a new strategy to integrate the complementary modalities of 19F magnetic resonance imaging (19F MRI) and fluorescence imaging (FI) into a polymer nanoprobe composed of hydrophobic fluorescent organic core and hydrophilic fluorinated polymer shell. The alkyne‐terminated fluorinated copolymer (Pn) of 2,2,2‐trifluoroethyl acrylate (TFEA) and poly(ethylene glycol) methyl ether acrylate (PEGA) was first prepared via atom transfer radical polymerization (ATRP). The PEGA plays an important role in both improving 19F signal and modulating the hydrophilicity of Pn. The alkynyl tail in Pn is readily conjugated with azide modified tetra‐phenylethylene (TPE) through click chemistry to form azo polymer (TPE‐azo‐Pn). The core‐shell nanoprobes (TPE‐P3N) with an average particle size of 57.2 ± 8.8 nm are obtained via self‐assembly with ultrasonication in aqueous solution. These nanoprobes demonstrate high water stability, good biocompatibility, strong fluorescence and good 19F MRI performance, which present great potentials for simultaneous fluorescence imaging and 19F–MR imaging.  相似文献   

14.
Interaction of 10‐methylacridinium iodide (MAI) as fluorescence probe with nucleobases, nucleosides and nucleic acids has been studied by UV‐visible absorption and fluorescence spectroscopy. It was found that fluorescence of MAI is strongly quenched by the nucleobases, nucleosides and nucleic acids, respectively. The quenching follows the Stern‐Volmer linear equation. The fluorescence quenching rate constant (kq) was measured to be 109‐1010 (L/mol)/s within the range of diffusion‐controlled rate limit, indicating that the interaction between MAI and nucleic acid and their precursors is characteristic of electron transfer mechanism. In addition, the binding interaction model of MAI to calf thymus DNA (ct‐DNA) was further investigated. Apparent hypochromism in the absorption spectra of MAI was observed when MAI binds to ct‐DNA. Three spectroscopic methods, which include (1) UV spectroscopy, (2) fluorescence quenching of MAI, (3) competitive dual‐probe method of MAI and ethidium bromide (EB), were utilized to determine the affinity binding constants (K) of MAI and ct‐DNA. The binding constants K obtained from the above methods gave consistent data in the same range (1.0–5.5) × 104L/mol, which lend credibility to these measurements. The binding site number was determined to be 1.9. The influence of thermal denaturation and phosphate concentration on the binding was examined. The binding model of MAI to ct‐DNA including intercalation and outside binding was investigated.  相似文献   

15.
New crown ether carrying two fluorionophores of cis‐dibenzothiazolyldibenzo‐24‐crown‐8 was synthesized from cis‐diformyldibenzo‐24‐crown‐8 and 2‐aminobenzenethiol. The binding behavior and the optical properties of the crown ether were examined through UV‐visible spectroscopy and fluorescence spectroscopy. When complexed with Na+, K+, Rb+, and Cs+ ions, it led to intramolecular charge transfer and caused the changes of the fluorescence spectra. The protonation of the crown ether was also studied. With protonation using CF3COOH, the absorption bands and the fluorescence spectroscopy changed, the maximal fluorescence wavelengths red shifted and the fluorescence intensity with the maximum at 433 nm enhanced strongly. J. Heterocyclic Chem., (2011).  相似文献   

16.
Oxophthalocyaninato(2–)molybdenum(IV), activated by bromine oxidation prior to use, reacts with fused triphenylphosphine in the presence of bis(triphenylphosphine)iminium bromide to yield linear-bis(triphenylphosphine)iminium trans-dibromophthalocyaninato(2–)molybdate(III), l(PNP)trans[Mo(Br)2pc2?]. It crystallizes triclinic with crystal data: a = 10.506(1) Å, b = 12.436(2) Å, c = 12.918(2) Å, α = 76.186(1)°, β = 67.890(1)°, γ = 68.689(1)°; space group P1 (No. 2); Z = 1. MoIII is in a pseudo-octahedral coordination geometry with the bromo ligands in trans-arrangement. The Mo? Np and Mo? Br distance is 2.043(10) and 2.588(1) Å, respectively. The PNP cation adopts a linear conformation. In the IR spectrum vas(Mo? Br) is observed at 218 cm?1 and vas(P? N) of the linear (P? N? P) core at 1406 cm?1. Cyclic and differential-pulse voltammetry show two quasi-reversible cathodic processes at ?1.15 and ?0.53 V vs. Ag/AgCl. The first is assigned to a phthalocyaninate directed reduction (pc2?/pc3?), while the latter arises from a Mo directed reduction (MoIII/MoII). Spectral monitoring confirms the reversible MoIII/MoII reduction. Two quasi-reversible anodic processes at 0.60 and 1.27 V are assigned to the successive Mo directed oxidation with redox couples MoIII/MoIV and MoIV/MoV. For the first time, three very intense spin-allowed trip-quartet transitions are observed in the electronic absorption spectra at 7140 (TQI), 16890 (TQ2) and 18700 cm?1 (TQ3) together with a sing-quartet transition at 15850 cm?1 and characteristic ?Q”? region with maximum at 28500 cm?1 and ?N”? region at 37400 cm?1. All electronic excitations are of comparable intensity. A prominent low temperature emission at 6690 cm?1 is assigned to a spin-forbidden trip-sextet.  相似文献   

17.
Stable dispersions of exfoliated graphene in aqueous media with the aid of the amphiphilic block copolymer poly(isoprene‐b‐acrylic acid) (PI‐b‐PAA), in the form of its anion, were used to electrostatically bind cationic 5,10,15,20‐tetrakis(1‐methyl‐4‐pyridinio)porphine tetra(p‐toluenesulfonate) (H2P4+). A new graphene/PI‐b‐PAA?–H2P4+ ensemble was formed and examined by dynamic light scattering, UV/Vis and fluorescence emission spectroscopy. The efficient fluorescence quenching of H2P4+ in the graphene/PI‐b‐PAA?–H2P4+ ensemble was probed by using steady‐state and time‐resolved photoluminescence, suggesting that electron/energy‐transfer phenomena occur within the nanoensemble. Blank experiments validated the concept of electrostatic interactions that govern the formation of graphene/PI‐b‐PAA?–H2P4+ ensemble, which signified the importance of graphene as an electron acceptor toward the preparation of some new donor–acceptor systems. Finally, kinetic analysis of the lifetime profiles of the fluorescence emission gave information regarding the quenching rate constant and quantum yield of the singlet excited state of H2P4+ in the graphene/PI‐b‐PAA?–H2P4+ ensemble.  相似文献   

18.
Seven novel fluorescence‐traced 1‐aryl‐2‐substituted‐3‐allyl‐1H‐benzimidazolium bromides ( 5a , 5b , 5c , 5d , 5e , 5f , 5g ) were synthesized by alkylation and quaternization of compounds 1‐aryl‐2‐substituted‐1H‐benzimidazoles ( 4a , 4b , 4c , 4d , 4e , 4f , 4g ) with excess allyl bromide in acetonitrile at refluxing temperature. Their structures were characterized by 1H‐NMR, MS, and elemental analysis. They emit violet‐blue light (λEmmax = 386–438 nm) with fluorescence quantum yields of 0.54 to 0.75 in aqueous solution.  相似文献   

19.
《Analytical letters》2012,45(2):295-306
Abstract

Fluorescein can emit strong and stable fluorescence. Cu2+ can oxidize fluorescein, which causes the fluorescence signal to diminish. Cu(DP)2+ (DP refers to α,α′‐dipyridyl) and Cu‐GPD‐4.0 (GPD‐4.0 refers to 4.0‐generations polyamidoamine dendrimers) both can catalyze Cu2+ to oxidize fluorescein, which causes the fluorescence signal to diminish sharply. The ΔF is directly proportional to the content of copper. Based on the facts above, a new catalytic fluorescence spectrophotometry for the determination of trace copper using Cu(DP)2+ and Cu‐GPD‐4.0 was established. The linear range of this method is 0.040–28 pg mL?1. The regression equation for working curve is ΔF=209.5+14.39 CCu 2+ (pg mL?1), n=7; correlation coefficient is 0.991. The detection limit of this method is 1.0×10?14 g mL?1. After replicate measurement times, RSDs are 3.1% and 4.2% for samples containing 0.040 and 28 pg mL?1 Cu2+, respectively. This method is rapid and precise with high sensitivity and good repeatability. The method has been applied to the determination of trace copper in tea and human hair with satisfactory results. Meanwhile, the mechanism for the determination of trace copper by catalytic fluorescence spectrophotometry using Cu(DP)2+ and Cu‐GPD‐4.0 was also discussed.  相似文献   

20.
A series of novel N‐glycosyl‐N′‐pyrazolylmethylene aminothioureas ( 4a‐4e, 5a‐5e ) were synthesized from N‐glycosyl‐N′‐aminothioureas ( 2a‐2d ) and 4‐formylpyrazole ( 3a‐3e ). Activated 4Å molecular sieves were adopted for dehydrated reagent to improve the reaction rate and yield. The structures of the new compounds were identified on the basis of IR, 1H NMR and MS spectra. Simultaneously, the compounds were detected by fluorescence spectrophotometer and had preferable fluorescence activity, so they can be selected as a kind of novel fluorescence labeled derivative of sugar.  相似文献   

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