A fluorescent chemosensor based on optically active 2,2′‐binaphtho‐20‐crown‐6 for metal ions

A chiral conjugated polymer can be obtained by the polymerization of (S)‐6,6′‐dibromo‐2,2′‐binaphtho‐20‐crown‐6 and 1,4‐divinyl‐2,5‐dibutoxybenzene via a palladium‐catalyzed Heck cross‐coupling reaction. The chiral conjugated polymer shows strong green‐blue fluorescence. The responsive properties of the chiral polymer to metal ions were investigated using fluorescence and UV‐visible absorption spectra. K⁺, Pb²⁺, Cd²⁺ and Ba²⁺ enhance the fluorescence of the polymer; in contrast, Hg²⁺ causes effective quenching of the fluorescence of the polymer. The obvious influences on the fluorescence indicate that the 2,2′‐binaphtho‐20‐crown‐6 moiety plays an important role in fluorescence recognition for Hg²⁺ due to the effective photo‐induced electron transfer or charge transfer between the conjugated polymer backbone and the receptor ions. The responsive properties of the polymer to metal ions show that the chiral conjugated polymer incorporating 2,2′‐binaphtho‐20‐crown‐6 moieties in the main‐chain backbone as recognition sites can act as an excellent fluorescent probe for the sensitive detection of Hg²⁺. Copyright © 2010 Society of Chemical Industry     

Synthesis of nitropyridine‐based π‐conjugated polymers and their chemical properties

π‐Conjugated poly(3‐nitropyridine‐2,5‐diyl) ( PPy‐3‐NO₂ ), poly(3,3′‐dinitro‐2,2′‐bipyridine‐5,5′‐diyl) ( PBpy‐3,3′‐diNO₂ ), and a poly(arylene ethynylene) type polymer consisting of a 3,3′‐dinitro‐2,2′‐bipyridine unit ( PAE‐1 ) were synthesized by Cu‐promoted Ullmann coupling reaction and Pd‐catalyzed coupling reaction. PPy‐3‐NO₂ and PAE‐1 were soluble in organic solvents such as DMSO, DMF, and chloroform, and gel permeation chromatography analysis showed a number average molecular weight (M_n) of 9,300 and 12,300, respectively. PPy‐3‐NO₂ gave intrinsic viscosity, [η], of 0.53 dL g^?1 in DMF. PBpy‐3,3′‐diNO₂ had somewhat lower solubility. The polymers exhibited a UV–vis peak at about 430 nm. PPy‐NO₂ received electrochemical reduction at ?1.5 V versus Ag⁺/Ag in acetonitrile, and gave an electrochemical redox cycle in a range from 0 to ?1.1 V versus Ag⁺/Ag in an aqueous solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1763–1767, 2006     

Synthesis and characterization of photoluminescent copolymer containing 1,1′‐binaphthyl and fluorene rings

The luminescent polymer, F‐DMBN, containing 2,2′‐dimethacrylanido‐1,1′‐binaphthyl (DMBN) and 9,9‐diphenylfluorene, is synthesized by the Heck reaction of halogenated and olefinic monomers. The structures are characterized by MS, ¹H‐NMR, and IR, and the photoluminescent properties are investigated by UV/vis absorption and fluorescence spectra. The results show that the polymer emits blue and blue–violet light. The luminescence quantum yield is 0.424 in ethanol and the emission spectra exhibit obvious solvent effects. In addition, the light emitting can be quenched by both electron donor (N,N‐dimethylaniline) and electron acceptor (fullerene), where the processes follow the Stern–Volmer equation. Moreover, the interaction between F‐DMBN and carbon nanotubes is also studied by fluorescent quenching. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 434–438, 2005     

Synthesis of novel bipyridyl ligands and application in preparation of polyketone

In this article, novel 2,2′‐bipyridyl derivatives were synthesized and the excellent bipyridyl ligands were chosen as catalyst to apply in the copolymerization of carbon monoxide (CO) and styrene (ST) to prepare polyketone. 4,4′‐Dicarboxyl‐2,2′‐bipyridine(4,4′‐dcpy) was synthesized by use of synthesized 4,4′‐dimethyl‐2,2′‐bipyridine(4,4′‐dmpy). The products (4,4′‐dmpy and 4,4′‐dcpy) were characterized by melting point, NMR, IR, GC‐MS, and elemental analysis. The effects of different ligands and various reaction conditions incuding the usage of ligand, p‐toluenesulfonic acid, solvent, p‐benzoquinone, the CO pressure, and reaction temperature on catalytic activity of the copolymerization were investigated. The catalytic activity of 4,4′‐dmpy, 4,4′‐dcpy and 2,2′‐bipyridine were compared. The results showed that the addition of the electron‐donating substituent can enhance catalytic activity, with the sequence as follows: 4,4′‐ dimethyl‐2,2′‐bipyridine > 2,2′‐bipyridine > 4, 4′‐carboxy 2,2′‐ bipyridine. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2012     

Designed magnetic multilayer thin films fabricated via the layer‐by‐layer assembly of polycyanofullerenes

The layer‐by‐layer self‐assembly technique was used to fabricate a series of multilayer thin films with poly[4′‐(4‐methacryloyphenyl)‐2,2′:6′,2″‐terpyridine] (PmPhtpy), polycyanofullerenes, and transition metals (Ni²⁺ and Co²⁺). The polymer PmPhtpy was prepared by free‐radical polymerization, and this was confirmed by Fourier transform infrared (FTIR) and ¹H‐NMR spectroscopy. The polycyanofullerenes, which were characterized by FTIR, ultraviolet–visible (UV–vis), and ¹³C‐NMR spectroscopy, was synthesized via the bromination of fullerene and then substitution with a nucleophilic reagent [potassium cyanide (KCN)]. The optical properties of the films were measured by attenuated total reflection infrared and UV–vis spectroscopy, and the results indicate that the driving force of the fabrication of the multilayer film was the coordination interaction. The magnetic behavior was examined as a function of the magnetic field strength at 5 K and the temperature (5–300 K). The magnetic hysteresis loops of the films showed a typical S shape at 5 K; this suggested soft ferromagnetic properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40681.     

Light‐triggered reversible solubility of α‐cyclodextrin and azobenzene moiety complexes in PDMAA‐co‐PAPA via molecular recognition

Photoresponsive polymer with azobenzene pendant group (PDMAA‐co‐PAPA) was synthesized by radical polymerization of N,N‐dimethylacrylamide (DMAA) and N‐4‐phenylazophenyl acrylamide (PAPA), and the characterization of the inclusion complexes of the PDMAA‐co‐PAPA with α‐cyclodextrin (α‐CD) were performed by FTIR, GPC, ¹H NMR, 2D NOESY, and UV–vis spectroscopy. It was found that the solubility of PDMAA‐co‐PAPA and α‐CD inclusion complexes in aqueous solution showed tunable property, which could be triggered by alternating UV–vis light irradiation at a certain temperature due to the effect of molecular recognition of α‐CD with azobenzene moiety in the polymer. After UV irradiation, the lower critical solution temperature (LCST) of the polymer aqueous solution increased slightly without α‐CD while the LCST decreased sharply at presence of α‐CD. Furthermore, UV spectroscopy showed that the photoisomerization of the polymer solution went on rapidly and reversibly, and 2D NOESY data suggested that the inclusion complexation of α‐CD with trans azobenzene moiety and the decomplexation with cis azobenzene resulted in reversible solubility behavior when objected to UV and Vis light irradiation alternately. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of the solvent polarity on the atom transfer radical polymerization of methyl methacrylate initiated by 4‐(chloromethyl)phenyltrimethoxysilane

The controllability of the atom transfer radical polymerization of methyl methacrylate in the polar solvent N,N‐dimethylformamide and the nonpolar solvent xylene with 4‐(chloromethyl)phenyltrimethoxysilane as an initiator and with CuCl/2,2′‐bipyridine and CuCl/4,4′‐di(5‐nonyl)‐2,2′‐bipyridine as catalyst systems was studied. Gel permeation chromatography analysis established that in the nonpolar solvent xylene, much better control of the molecular weight and polydispersity of poly(methyl methacrylate) was achieved with the CuCl/4,4′‐di(5‐nonyl)‐2,2′‐bipyridine catalyst system than with the CuCl/2,2′‐bipyridine as catalyst system. In the polar solvent N,N‐dimethylformamide, unlike in xylene, the polymerization was more controllable with the CuCl/2,2′‐bipyridine catalyst system than with the CuCl/4,4′‐di(5‐nonyl)‐2,2′‐bipyridine catalyst system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2751–2754, 2007     

Synthesis and properties of polymer from bis‐3,4‐ethylenedioxythiophene substituted acenaphthenequinoxaline

A new electrochoromic polymer poly(8,11‐bis(3,4‐ethylenedioxy thiophen‐2‐yl)acenaphtho[1,2‐b]‐quinoxaline) (PBEAQ) was synthesized by electrochemical polymerization of the corresponding monomer (BEAQ) in a 0.1 M tetraethylammonium tetrafluoroborate (TEABF₄) dichloromethane–acetonitrile (2 : 1, v : v) solution. The monomer and polymer were characterized by elemental analysis, ¹H‐NMR, IR, and UV‐vis spectroscopy. The electrochemical and optical properties of polymer were investigated by cyclic voltammetry and UV‐vis spectroscopy. Cyclic voltammetry and spectroelectrochemistry studies demonstrated that the polymer can be reversibly reduced and oxidized (both n‐ and p‐doped) between ?2 V and +1.5 V vs. Ag/Ag⁺. The polymer had a transmissive light blue color in the oxidized state and reddish color in the reduced state. Undoped polymer shows UV‐vis absorption peaks at 615 nm in solution, 650 nm in solid state, and has an optical band gap of 1.5 eV. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of the soluble fluorescent poly[2‐decyloxy‐5‐(2′‐(6′‐dodecyloxy)naphthyl)‐1,4‐phenylenevinylene]

A new soluble fluorescent polymer, poly[2‐decyloxy‐5‐(2′‐(6′‐dodecyl‐oxy)naphthyl)‐1,4‐phenylenevinylene] (DDN‐PPV), with no tolane‐bisbenzyl (TBB) structure defects is prepared by the dehydrohalogenation of 1,4‐bis(bromomethyl)‐2‐decyloxy‐5‐(2′‐(6′‐dodecyloxy)naphthyl)benzene (as monomer) in this study. The aforementioned monomer is synthesized via such chemical reactions as alkylation, bromination, and Suzuki coupling reactions. The structure and properties of the DDN‐PPV are examined by ¹H NMR, FTIR, UV/vis, TGA, photoluminescence (PL), and electroluminescence (EL) analyses. The two asymmetric decyloxy and 6′‐dodecyloxynaphthyl substituents on the phenylene ring make the DDN‐PPV soluble in organic solvents and eliminate the TBB structure defects. With the DDN‐PPV acting as a light‐emitting polymer, a device is fabricated with a sequential lamination of ITO/PEDOT/DDN‐PPV/Ca/Ag. The EL spectrum of the device shows a maximum emission at 538 nm. The turn on voltage of the device is about 16.6 V. Its maximum brightness is 14 cd/m² at a voltage of 18.2 V. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2734–2741, 2007     

Synthesis of star–comb‐shaped polymer with porphyrin‐core and its self‐assembly behavior study

5,10,15,20‐tetra(4‐hydroxyphenyl)porphyrin (THPP) was synthesized by the condensation of pyrrole with 4‐hydroxybenzaldehyde in the presence of solvent (propionic acid). Subsequently, the resulting THPP was converted to a tetrafunctional star‐shaped macroinitiator (porphyrin‐Br₄) by esterification of it with 2‐bromopropanoyl bromide, and then atom transfer radical polymerization (ATRP) of styrene was conducted at 110°C with CuCl/2,2′‐bipyridine as the catalyst system. The resulting product was reacted with NBS to obtain star‐shaped initiator porphyrin‐(PSt‐Br)₄, which was used the following ATRP of the GMA to synthesize star–comb‐shaped grafted polymer porphyrin‐(PSt‐g‐PGMA)₄. The number molecular weight was 2.3 × 10⁴ g/mol, and the dispersity was narrow (M_w/M_n = 1.32). The structure of the polymers was investigated by NMR, UV–vis, IR, and GPC measurement. The self‐assembly behavior of the polymer porphyrin‐(PSt‐g‐PGMA)₄ was studied by DLS and AFM. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis,Characterization and Application of New Rhodium Complexes for Indirect Electrochemical Cofactor Regeneration

Electroenzymatic synthesis often suffers from electrochemical reaction steps which proceed slower than the coupled enzyme reaction. For indirect electrochemical cofactor regeneration, we here report two new mediators with superior properties compared to the established rhodium complex (2,2′‐bipyridyl)(pentamethylcyclopentadienyl)rhodium [Cp*Rh(2,2′‐bipyridine)]. After constructing a robotic system for fast and reliable cyclic voltammetry measurements, we screened twelve rhodium complexes with substituted 2,2′‐bipyridine ligands for their reduction potentials and catalytic activity towards the reduction of NADP. Promising complexes were investigated in more detail by cyclic voltammetry and under batch electrolysis conditions. The new complexes Cp*Rh(5,5′‐methyl‐2,2′‐bipyridine) and Cp*Rh(4,4′‐methoxy‐2,2′‐bipyridine) reduced NADP to NADPH three times faster than the established mediator, resulting in volumetric productivities of up to 136 mmol L⁻¹ d⁻¹ and turnover frequencies of up to 113 h⁻¹. This increased reaction rate of these new mediators makes indirect electrochemical approach significantly more competitive to other methods of cofactor regeneration. Abbreviations: ADH=alcohol dehydrogenase; Ag|AgCl=silver|silver chloride reference electrode; bpy=2,2′‐bipyridine; ci=current increase; Cp*=pentamethylcyclopentadienyl; CV=cyclic voltammetry; Ep=peak potential; equiv=equivalent; NADP/NADPH=nicotinamide adenine dinucleotide phosphate oxidised/reduced form.     

Synthesis of telechelic C60 end‐capped polymers under microwave irradiation

Bromo‐Double‐Terminated polystyrene (Br‐PSt‐Br) and poly(methyl methacrylate) (Br‐PMMA‐Br) with predesigned molecular weight and narrow polydispersity were prepared by atom transfer radical polymerization (ATRP) using the initiating system aa′‐dibromo‐p‐xylene(DBX) / CuBr/2,2′‐bipyridine(bipy). The precursor bromo‐terminated polymers were subsequently functionalized with fullerene C₆₀ using CuBr/bipy as the catalyst system under microwave irradiation (MI). The telechelic C₆₀ end‐capped products were characterized by gel permeation chromatography (GPC), UV‐vis, FT‐IR, TGA, DSC, ¹H NMR, and ¹³C NMR. The results showed that microwave irradiation could significantly increase the rate of fullerenation reaction, and the physical properties and structure of the C₆₀ end‐capped polymers are not modified by the use of the microwave. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 828–834, 2006     

Fluorescent chemosensor for metal ions based on optically active polybinaphthyls and 1,3,4-oxadiazole

Linear chiral polymers P-1 and P-2 were synthesized by the polymerization of (R)-5,5′-dibromo-6,6′-di(4-methylphenyl)-2,2′-bisoctoxy-1,1′-binaphthyl (R-M-1) with 2,5-di(4-vinylphenyl)-1,3,4-oxadiazole (M-2) and 2,5-di(4-tributylstannylphenyl)-1,3,4-oxadiazole (M-3) via Heck and Stille cross-coupling reaction, respectively. The chiral conjugated polymer P-1 can show strong green-blue fluorescence, and the chiral polymer P-2 shows strong blue fluorescence. While the conjugated polymers P-1 and P-2 were used as fluorescent chemosensor for metal ions, their fluorescence can be efficiently quenched on the addition of different metal ions. The obvious quenching effect of the polymers P-1 and P-2 indicates that the intramolecular photoinduced electron transfer (PET) or photoinduced charge transfer (PCT) between the polymer backbone and receptor-ions in the main chain of fluorescent chemosensor can lead to the pronounced fluorescence quenching. The results also show that the chiral polymers P-1 and P-2 incorporating 1,3,4-oxadiazole moiety as the recognition site can act as a special fluorescent chemosensor for the appropriate detection of the sensitive and selective sense of metal ions.     

Synthesis and photophysical behavior of a water‐soluble coumarin‐bearing polymer for proton and Ni2+ ion sensing

BACKGROUND: In recent years, many fluorescent chemosensors with various macromolecular structures have been prepared for the detection of protons or metal cations in the environment. Most of this research is focused on polymer sensors with fluorescent recognition sites in the main chain. In this case, the fluorescent recognition sites are covalently bonded to the polymer chain, and thus the polymer shows photophysical properties as a chemosensor for protons and metal ions. RESULTS: An acrylic monomer bearing coumarin moieties, 7‐hydroxy‐4‐methyl‐8‐(4′‐acryloylpiperazin‐1′‐yl)methylcoumarin, was synthesized. This was then copolymerized with N‐vinylpyrrolidone to obtain a blue fluorescent material. The fluorescent copolymer has good solubility in aqueous solution. Its main photophysical properties were determined in relation to its use as a sensor for protons and metal cations. It is an efficient ‘off‐on’ switcher for pH between 3.02 and 12.08. Additionally, the polymer sensor is selective to Ni²⁺ ions, with the increase in the fluorescence intensity depending on Ni²⁺ ion concentrations in the range 0.33 × 10^?5–7.67 × 10^?5 mol L^?1. CONCLUSION: The results suggest that this copolymer may offer potential as a reusable polymer sensor for protons and Ni²⁺ ions in aqueous solution. Copyright © 2009 Society of Chemical Industry     

Mechanical and thermal characterization of iron(II) 2,2′‐bipyridine complex supported polyacrylonitrile fiber as a novel photocatalyst

In this study, the mechanical and thermal properties of amidoximated polyacrylonitrile fibers immobilized with iron(II) 2,2′‐bipyridine complex (Fe(bpy)₃²⁺) have been investigated to support their commercial application for wastewater treatment. The mechanical properties were evaluated with respect to breaking strength and elongation at break in both dry and wet conditions. Dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis techniques were used to determine the thermal behavior. The results indicate the effect of Fe(bpy)₃²⁺ immobilization on the breaking strength of the dry fiber samples were negligible, and the corresponding elongation at break decreased gradually with Fe(bpy)₃²⁺ content increasing. In addition, water treatment greatly affected the mechanical properties of the fibrous materials. Thermal studies reveal that Fe(bpy)₃²⁺ immobilization led to better fiber thermal stabilization in terms of higher storage modulus at high temperature regions, larger glass transition temperature, and smaller weight loss. The 2,2′‐bipyridine ligands were found to be responsible for the better mechanical and thermal performance of the fibrous materials by enhancing the intermolecular crosslink. POLYM. ENG. SCI., 55:1052–1058, 2015. © 2014 Society of Plastics Engineers     

Poly[6‐(2,6‐bis(1′‐methylbenzimidazolyl)pyridin‐4‐yloxy)hexyl acrylate] (PBIP) and its terbium (III) complex (PBIP‐Tb3+): Homopolymerization,optical, and magnetic performance

Poly[6‐(2,6‐bis(1′‐methylbenzimidazolyl)pyridin‐4‐yloxy)hexyl acrylate] (PBIP) and its terbium complex (PBIP‐Tb³⁺) were prepared and characterized by ¹H NMR and FT‐IR. The optical properties of PBIP‐Tb³⁺ complex were characterized by UV–vis spectroscopy and fluorescence spectroscopy. Both polymer PBIP and PBIP‐Tb³⁺ complex show good thermal stability. The magnetic property of PBIP‐Tb³⁺ complex was measured as a function of temperature (5–300 K) at 30 kOe and as a function of an external field (?50 to 50 kOe) at 5 K. Magnetic hysteresis loop of PBIP‐Tb³⁺ complex at 5 K shows typical “S” shape and PBIP‐Tb³⁺ complex is soft ferromagnetic. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44249.     

Synthesis and characterization of imine polymers containing aliphatic and aromatic groups and some of Schiff base‐metal complexes

In this study, the oxidative polycondensation reaction conditions of 2,2′‐[(2,5‐dichloro‐1,4‐phenylene)bisnitrilomethylylidene]diphenol (DCPMDP) were studied between 40 and 90°C using different times and concentrations in the alkaline medium to determine effect on the yield of these parameters. Polymerization of 2,2′‐piperazine‐1,4‐diylbis[propane‐3,1‐diylnitrilomethylylidene]diphenol (PDMDP) was performed at two steps with graft polycondensation method. Additionally, seven different metal complexes were also synthesized from PDMDP with some metal salts. The structures of the compounds were confirmed by UV–vis, FT‐IR, ¹H and ¹³C NMR spectroscopy analyses. The characterization was made by TG‐DTA, size exclusion chromatography (SEC), elemental analysis, and solubility tests. HOMO‐LUMO energy levels and electrochemical band (E_g′) gaps were determined from cyclic voltammetry (CV) measurements. Also, optical band (E_g) gaps were calculated from UV–vis measurements. Electrical conductivity of doped and undoped monomer and oligomer were measured by four‐point probe technique using an electrometer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and adsorption properties,toward some heavy metal ions,of a new polystyrene‐based terpyridine polymer

A novel polymeric ligand having 2,2′:6′,2″‐terpyridine as pendant group was prepared through a Williamson type etherification approach for the reaction between 4′‐hydroxy‐2,2′: 6′,2″‐terpyridine and the commercially available 4‐chloromethyl polystyrene. The chelating properties of the new polymer toward the divalent metal ions (Cu²⁺, Zn²⁺, Ni²⁺, and Pb²⁺) in aqueous solutions was studied by a batch equilibration technique as a function of contact time, pH, mass of resin, and concentration of metal ions. The amount of metal‐ion uptake of the polymer was determined by using atomic absorption spectrometry. Results of the study revealed that the resin exhibited higher capacities and a more pronounced adsorption toward Pb²⁺ and that the metal‐ion uptake follows the order: Pb²⁺ > Cu²⁺ > Zn²⁺ > Ni²⁺. The adsorption and binding capacity of the resin toward the various metal ions investigated are discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of vinyl polymers bearing photo‐labile diethylthiocarbamoylthiyl (S2CNEt2) groups via ATRP

Direct synthesis of vinyl polymers functionalized with photo‐labile diethylthiocarbamoylthiyl (S₂CNEt₂) groups was reviewed via three living polymerization procedures: normal atom‐transfer radical polymerization (ATRP), reverse ATRP and photo ATRP. The S₂CNEt₂ group was transferred by mediating the dormant–active species equilibrium in the course of polymerization and eventually ω‐terminating the resulting polymer chain. ATRP of methyl methacrylate (MMA) was successfully performed with a p‐toluenesulfonyl chloride/Cu(S₂CNEt₂)/2,2′‐bipyridine(bpy) or benzoyl peroxide (BPO)/Cu(S₂CNEt₂)/bpy initiation system. The oxidized complex, Cu(S₂CNEt₂)Cl/bpy, catalyzed the reverse ATRP of vinyl monomers initiated with BPO or 2,2′‐azobisisobutyronitrile (AIBN), producing tailor‐made polymers with ω‐S₂CNEt₂ groups and a narrow molecular‐weight distribution. Without external ligands, the living polymerization of vinyl monomers was achieved under the thermal initiation of diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS) in conjunction with Fe(S₂CNEt₂)₃ catalyst. Photo ATRP of MMA and styrene was first realized in the presence of 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA)/Fe(S₂CNEt₂)₃ under UV irradiation at ambient temperature. Copyright © 2004 Society of Chemical Industry     

An Efficient Lanthanide‐Dependent DNAzyme Cleaving 2′–5′‐Linked RNA

RNA can form two types of linkage. In addition to the predominant 3′–5′ linkage, 2′–5′‐linked RNA is also important in biology, medicine, and prebiotic studies. Here, in vitro selection was used to isolate a DNAzyme that specifically cleaves 2′–5′ RNA by using Ce³⁺ as the metal cofactor, but leaves the 3′–5′ counterpart intact. This Ce5 DNAzyme requires trivalent light lanthanide ions and shows a rate of 0.16 min^?1 in the presence of 10 μm Ce³⁺; the activity decreases with heavier lanthanide ions. This is the fastest DNAzyme reported for this reaction, and it might enable applications in chemical biology. As a proof‐of‐concept, using this DNAzyme, the reactions between phosphorothioate‐modified RNA and strongly thiophilic metals (Hg²⁺ and Tl³⁺) were studied as a function of pH.