Electrogenerated chemiluminescence. XXIV. Electrochemistry and electrogenerated chemiluminescence of 9,10-dichloro-9,10-dihydro-9,10-diphenylanthracene

A study of the electrochemistry and electrogenerated chemiluminescence (e.c.l.) of 9,10-dichloro-9,10-dihydro-9,10-diphenylanthracene (DPACl₂) in acetonitrile solutions using rotating ring—disk electrode and stationary electrode techniques is described. The measured e.c.l. efficiency was about 0.1 to 0.8%, smaller than that observed for the corresponding DPA radical ion annihilation e.c.l. The emission is independent of applied external magnetic field, supporting the mechanism involving direct formation of emitting singlet. The e.c.l. emission and the electroreduction of DPACl₂ depend on the chloride concentration in the solution; the results suggest that this dependence is an electrode surface effect.     

Electrogenerated chemiluminescence,a chemiluminescent polymer based on poly(vinyl-9,10-diphenylanthracene)

The electrochemistry, absorption, photoluminescence and electrogenerated chemiluminescence (ECL) of poly(vinyl-9,10-diphenylanthracene) thin films on various substrates in various solvents is described. The electrochemical behavior of the polymer film is very similar to that for 9,10-diphenylanthracene (DPA) in N,N-dimethylformamide, indicating that the multiple electroactive groups in the polyvinyl chain do not interact strongly. In situ absorbance measurements of the neutral, oxidized, or reduced polymer films indicate that all of the pendant DPA groups in the chain are electrochemically active during oxidation and reduction. Absorption, photoluminescence, and ECL spectra after potential pulsing or cyclic voltammetric experiments show the presence of components at longer wavelengths than those for the precursor molecules. Such longer wavelength components might be, as in the case of DPA, attributed to the formation of stable products from the decomposition of DPA radical ions.     

Electrogenerated chemiluminescence detection of single entities

Electrogenerated chemiluminescence, also known as electrochemiluminescence (ECL), is an electrochemically induced production of light by excited luminophores generated during redox reactions. It can be used to sense the charge transfer and related processes at electrodes via a simple visual readout; hence, ECL is an outstanding tool in analytical sensing. The traditional ECL approach measures averaged electrochemical quantities of a large ensemble of individual entities, including molecules, microstructures and ions. However, as a real system is usually heterogeneous, the study of single entities holds great potential in elucidating new truths of nature which are averaged out in ensemble assays or hidden in complex systems. We would like to review the development of ECL intensity and imaging based single entity detection and place emphasis on the assays of small entities including single molecules, micro/nanoparticles and cells. The current challenges for and perspectives on ECL detection of single entities are also discussed.

We summarize the history and recent development that has been made in the ECL detection of single entities.     

电化学发光法测定盐酸普鲁卡因

基于盐酸普鲁卡因对鲁米诺在中性介质中铂电极上电化学发光的催化增敏作用 ,建立了测定盐酸普鲁卡因电化学发光新方法。电化学发光强度与盐酸普鲁卡因质量浓度在 4 .0× 1 0 -7～6 .0× 1 0 -6g mL范围内有良好的线性关系 ,检测限为 2 .0× 1 0 -7g mL,相对标准偏差为 4 .4 %。该方法已用于针剂中盐酸普鲁卡因的测定     

Electrogenerated chemiluminescence of triazole-modified deoxycytidine analogues in N,N-dimethylformamide

Triazole-modified deoxycytidines have been prepared for incorporation into single-stranded deoxyribonucleic acid (ssDNA). Electrochemical responses and electrogenerated chemiluminescence (ECL) of these deoxycytidine (dC) analogues, 1-4, were investigated as the monomers. Cyclic voltammetry and differential pulse voltammetry techniques were used to determine the oxidation and reduction potentials of 1-4, along with the reversibility of their electrochemical reactions. The dC analogues, in N,N-dimethylformamide containing 0.1 M tetra-n-butylammonium perchlorate as electrolyte, exhibited weak relative ECL efficiencies following the annihilation mechanism, while these efficiencies were enhanced with the use of benzoyl peroxide following the coreactant mechanism. It was shown that these nucleosides could generate excited monomers, and excimers as seen by the red-shifted ECL maxima relative to their corresponding photoluminescence peak wavelengths.     

Electrogenerated chemiluminescence in an electrodeposited redox hydrogel

We report the electrodeposition, under physiological conditions, of an electrochemiluminescent (ECL) Ru^2+/3+ complex-containing redox hydrogel. The ECL-hydrogels were formed by potential cycling of a solution of [poly(4-vinylpyridine)Ru(2,2′-bipyridine)²Cl^?]^+/2+, its un-coordinated backbone pyridines partially quaternized with bromoethylamine for solubility in water and for swelling to a hydrogel after crosslinking. The polymer was electrosorbed on plasma-oxidized graphite in the anodic half of the cycle and irreversibly crosslinked, to form a swelling but insoluble film, in the cathodic half cycle. The ECL resulted of the chemical reaction of electro-oxidatively produced tri-n-propylamine-radical with the hydrogel’s Ru²⁺ centers. The emission spectra of the photo-excited films and their ECL spectra were identical. The ECL-emission increased one thousand-fold, linearly with the tri-n-propylamine (TPrA) concentration, between 100 nM and 0.1 mM.     

Use of 9,10-diphenylanthracene as a contrast agent in chemiluminescence imaging: The observation of spreading of oxidative degradation in thin polypropylene films

Thin films of polypropylene were doped with a chemiluminescence (CL) activator, 9,10-diphenylanthracene (DPA), and were thermally oxidised in a CL imaging apparatus to determine whether heterogeneous oxidation processes such as spreading of oxidation could be observed. The presence of DPA resulted in significantly more intense CL images compared with undoped polymer, due to the efficient chemically induced electron exchange luminescence reaction between DPA and hydroperoxides. Hence, the CL images from DPA-doped PP were used to locate the position of hydroperoxides in the oxidising polymer. For thermal oxidation at 150 and 140 °C hydroperoxides were observed to form in localised regions of the films, whilst other areas remained hydroperoxide free. As the oxidation time increased the concentration of hydroperoxides in these areas increased and they were observed to spread to the remainder of the polymer. Time-resolved line maps from the images indicated that zones with high concentration of hydroperoxides travel through the polymer during oxidation. Integrals of CL images from the thermal oxidation of DPA-doped polymers indicated that a significant degree of oxidation had occurred by the end of the “induction period” for a conventional CL-intensity oxidation-time profile. This is a likely reason why spreading of oxidation has not previously been observed for undoped PP films.     

Electrogenerated chemiluminescence of single conjugated polymer nanoparticles

We demonstrate a novel and powerful method to study electrogenerated chemiluminescence (ECL) of single nanoparticles (NPs) (r = 25 +/- 15 nm) of a conjugated polymer, F8BT, on an ITO electrode in the presence of a co-reactant, such as tri-n-propylamine (TPrAH) in acetonitrile solution. The results reveal that the maximum formation rate of ECL of individual NPs is achieved after a long "build-up" time (10-40 s after pulse application). The high number of detected ECL photons from individual NPs (1500 photons during 100 s) highlights the potential of this technique as a very sensitive analytical method. Additionally, TPrAH acts as a very efficient protecting agent against irreversible electrochemical processes occurring in F8BT, as found in photoluminescence studies. This protection mechanism probably involves the neutralization of holes at the particle surface via electron transfer by both TPrAH and TPrA radical (TPrA*).     

A new access to the anthracene core: Synthesis of two water soluble singlet oxygen traps derived from 1,3-diphenylisobenzofuran and 9,10-diphenylanthracene

Two water soluble¹O₂ traps: dipotassium 1,3 - diphenylisobenzofuran - 5,6 - dicar?ylate and tetrapotassium 9,10 - diphenylanthracene - 2,3,6,7 - tetracar?ylate have been prepared in good yields and a new access to the anthracene skeleton is described. The key-step of this synthesis consists of a cycloaddition between 1,3 - diphenylisobenzofurans and dimethyl 7 - oxabicyclo[2.2.1] - 5 - heptene - 2,3 - dicar?ylate; the adducts thus obtained undergo dehydration to afford the corresponding anthracenes.     

Electrogenerated chemiluminescence of fluorescein in aqueous alkaline solutions

Fluorescein is shown to emit light when electrolyzed either anodically or cathodically using potential pulses, in aqueous alkaline solutions at a platinum electrode.     

Theoretical investigation of hole mobility in 9,10-diphenylanthracene by density functional calculations

The charge transfer property of the 9,10-diphenylanthracene (DPA) single-crystal system was investigated by density functional calculations. The hole mobility of DPA was predicted according to a hopping mechanism and compared with that of two standard organic single-crystal systems, namely, naphthalene and anthracene. The reorganization energy was calculated by the adiabatic potential energy surface method. The electronic coupling matrix elements were calculated by two methods, namely, the energy splitting in dimer (ESD) method and charge transfer integral (CTI) method. Using the coupling matrix calculated by the CTI method, we predicted a hole mobility of 2.15?cm²/(Vs) for DPA, whereas the CTI method gives the values of 0.35 and 1.39?cm²/(Vs) for naphthalene and anthracene, respectively. It is shown that the electronic coupling calculated by the CTI method gives the qualitatively satisfactory result for the hole mobilities of the three single-crystal systems.     

The photoperoxidation of unsaturated organic molecules. Intersystem crossing in 9,10-diphenylanthracene

Measurements of the quantum yield of 9,10-diphenylanthracene autoperoxidation as a function of dissolved oxygen concentration in benzene at 25°C are consistent with an intersystem crossing yield of 0.13 ± 0.03 for this molecule and the absence of the spin-allowed exothermic process S₁ + O₂³Σ → T₁ + O₂ Δ. These conclusions indicate the presence of a second triplet state below S₁.     

Synthesis and properties of thermotropic liquid-crystalline polyesters containing 9,10-diphenylanthracene moiety in the main chain

We synthesized thermotropic liquid-crystalline polyesters in which 9,10-diphenylanthracene moieties are incorporated into the main chain type of polyester forming the chiral smectic C (Sm C*). The polymers were prepared by the isopropyltitanate-catalyzed reaction of biphenyldicarboxylic acid and the corresponding diols, with different ratios of diol of 9,10-diphenylanthracene moiety to the alkane diols (1, 5, and 10 mol %) under nitrogen atmosphere. The polymers exhibited thermotropic liquid crystals despite the presence of a bulky diphenylanthracene moiety in the main chain. The circular dichroism spectra revealed that a Sm C* phase was formed in the polymer with 1 mol % of anthracene moiety, although only an Sm A phase was formed in the other polymers. This is the first example of a Sm C* polyester containing a diphenylanthracene moiety in the main chain. Furthermore, we measured the optical properties of the polymers and found that they exhibited very high fluorescent efficiency. The fluorescence spectra of the thin film differed from that of a CH₂Cl₂ solution.     

The doping effect of fluorinated aromatic solvents on the rate of ruthenium-catalysed olefin metathesis

A study concerning the effect of using a fluorinated aromatic solvent as the medium for olefin metathesis reactions catalysed by ruthenium complexes bearing N-heterocyclic carbene ligands is presented. The use of fluorinated aromatic hydrocarbons (FAH) as solvents for olefin metathesis reactions catalysed by standard commercially available ruthenium pre-catalysts allows substantially higher yields of the desired products to be obtained, especially in the case of demanding polyfunctional molecules, including natural and biologically active compounds. Interactions between the FAH and the second-generation ruthenium catalysts, which apparently improve the efficiency of the olefin metathesis transformation, have been studied by X-ray structure analysis and computations, as well as by carrying out a number of metathesis experiments. The optimisation of reaction conditions by using an FAH can be regarded as a complementary approach for the design of new improved ruthenium catalysts. Fluorinated aromatic solvents are an attractive alternative medium for promoting challenging olefin metathesis reactions.     

Fluorescence lifetimes and relative quantum yields of 9,10-diphenylanthracene in dilute solutions of cyclohexane and benzene

The lifetimes of 9,10-diphenylanthracene in dilute solutions of cyclohexane and benzene at 25°C have been found to be 7.58 ± 0.04 and 6.95 ± 0.04 ns respectively. Measurements of the relative quantum yields show that the dependence on the solvent is caused by an increased probability for non-radiative decay in benzene compared with cyclohexane. This behaviour is shown to partly reconcile previous conflicting data on the radiative properties of this molecule.     

One-pot synthesis of partially fluorinated naphthalene, anthracene, and chrysene derivatives

A series of partially fluorinated naphthalene, anthracene, and chrysene derivatives have been synthesized by a convenient one-pot reaction of multi-fluorinated aromatics and 1,4-dilithio-1,2,3,4-tetraaryl-1,3-butadiene that was generated in situ from the reduction of diphenylacetylene derivatives with lithium naphthalenide.     

Rates of the halide ion cleavage from halo-9,10-diphenylanthracene anion radicals in DMF

The rate constants k for the cleavage of the carbon-halogen bond in anion radicals of 1- and 2-chloro-9,10-diphenylanthracene, 9,10-dichloroanthracene and 2-bromo-9,10-diphenylanthracene have been determined and compared with the literature data for other anthracenyl halides. There is no significant correlation between log k and the formal potentials of the anion radical formation. However, linear relationships of the experimental RT In k vs. the relative thermodynamic contribution to the activation barrier as well as the relative intrinsic activation energy (calculated on the basis of the recent Savéant model and using the ionic component of the bond enthalpy estimated from the absolute electronegativity and hardness) have been found.     

Electrogenerated chemiluminescence aptamer-based biosensor for the determination of cocaine

A novel electrogenerated chemiluminescence aptamer-based (ECL-AB) biosensor for the determination of a small molecule drug is designed employing cocaine-binding aptamer as molecular recognition element for cocaine as a model analyte and ruthenium complex served as an ECL label. A 5′-terminal cocaine-binding aptamer with the ECL label at 3′-terminal of the aptamer was utilized as an ECL probe. The ECL-AB biosensors were fabricated by immobilizing the ECL probe onto a gold electrode surface via thiol-Au interactions. An enhanced ECL signal is generated upon recognition of the target cocaine, attributed to a change in the conformation of the ECL probe from random coil-like configuration on the probe-modified film to three-way junction structure, in close proximity to the sensor interface. The integrated ECL intensity versus the concentration of cocaine was linear in the range from 5.0 × 10⁻⁹ to 3.0 × 10⁻⁷ M. The detection limit was 1.0 × 10⁻⁹ M. This work demonstrates that the combination of a highly binding aptamer to analyte with a highly sensitive ECL technique to design ECL-AB biosensor is a great promising approach for the determination of small molecule drugs.