Diethyloxadicarbocyanine Iodide Research Articles

A combination of vortex-assisted liquid–liquid microextraction with fluorescence detection: An innovative approach for a green and highly sensitive determination of sodium dodecyl sulfate in water samples and pharmaceuticals

A new green, highly sensitive, and selective method based on a combination of vortex-assisted liquid–liquid microextraction with fluorescence detection (VALLME-FLD) was developed for the determination of sodium dodecyl sulfate (SDS). The method is based on the reaction of SDS with the fluorophore 3,3′-diethyloxadicarbocyanine iodide (DODC) at pH 3, followed by VALLME of the formed ion associate (IA) into a microvolume of the organic phase (n-amyl acetate). Fluorescence measurements were made at 668 nm, with excitation at 635 nm. During the optimization, the influence of various chemical and physical factors on the relative fluorescence intensity was studied. The linearity of the calibration curve was observed in two concentration ranges of SDS, from 0.30 to 3.0 µg L-1, R2 = 0.9980 (microextraction into 70 µL n-amyl acetate), and 3.0 to 14.0 µg L-1, R2 = 0.9960 (microextraction into 500 µL n-amyl acetate). The limits of detection (LOD) were 0.10 µg L-1 and 0.90 µg L-1, respectively. The accuracy and precision of the proposed method were verified during two consecutive days with a relative standard derivation of 2.2–4.9 % and recovery of 93.3–106.7 %. The system showed high selectivity towards SDS in the presence of at least 200-times higher concentrations of NO3–; 500-times higher concentrations of F-, Br-, HPO42-, and Fe2+, and 1000-times higher concentrations of CO32–, SO42-, Cl-, Mg2+, and Ca2+. The method was developed and applied to the determination of SDS/anionic surfactants in real water samples and pharmaceutical tablets.

Estimation of ground and excited-state dipole moments of three symmetric carbocyanine dyes via the analysis of luminescence properties

The solvatochromic effect of solvents on the absorption and fluorescence spectra of three carbocyanine dyes, namely 1,1′,3,3,3′,3′-hexamethylindocarbocyanine chloride (HIC); 1,1′,3,3,3′,3′-hexamethylindodicarbocyanine iodide (HIDC); and 3,3′-diethyloxadicarbocyanine iodide (DODC), have been investigated. The experimental ground and excited-state dipole moments of the dyes have been estimated via the well-known models by Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet, and the Dimroth-Reichardt’s empirical model. The influence of the solvation effect on the luminescence quantum yields was also examined and a strong correlation between the luminescence quantum yield values and the solvent viscosity was established. The fluorescence signal enhancement sensitivities between dyes were compared based on the Förster-Hoffmann equation. DFT and TDDFT calculations at the CAM-B3LYP/6-31G(d,p) level of theory were performed for the analysis of the nature of the electron transitions in absorption and excitation processes. Six phases different in polarity were considered during these computations, namely the gas, toluene, chloroform, acetone, methanol, and water. Transition electron density plots, Mulliken atomic partial charges, and Mayer bond orders were used for the analysis of the redistribution of electron density upon excitation. The specific behavior of the dyes in the glycerol medium was interpreted via the analysis of non-covalent interactions between the dye and glycerol molecules in terms of the reduced density gradient method.

Photophysics of a cyanine dye within cyclodextrin cavity

The modulated photophysical and dynamical behavior of a potent anti-tumor photosensitizer 3,3/-diethyloxadicarbocyanine iodide (DODCI) following host-guest inclusion complex formation with α-, β- and γ-Cyclodextrins (CDs) has been studied using steady-state and time-resolved spectroscopic methods. The cavity size of the CDs (α-CD <β-CD <γ-CD) is argued to play an instrumental role underlying the formation of the host-guest inclusion complex. While negligible interaction with α-CD is found to be succeeded by prominent quenching of monomeric fluorescence of the dye within β-CD and γ-CD with the degree of quenching being greater within γ-CD. The most appealing fact attained from the experimental results is the anticipation of dimer formation of DODCI within the large cavity of γ-CD which can entrap more than one molecule of DODCI. The steady-state results are found to be adequately corroborated by time-resolved fluorescence decay studies. Such encapsulation of the cyanine dye within the carrier cargo can be designed for targeted delivery inside biological systems.

A fully automated system with an optical immersion probe (OIP) for high-precision spectrophotometric measurements

A new and fully automated system with the interconnection of an Optical Immersion Probe (OIP) – pH meter – peristaltic pump was used to study the spectral and protolytic properties of carbocyanine the dyes 1,1′,3,3,3′,3′-hexamethylindocarbocyanine chloride (HIC); 1,1′,3,3,3′,3′-hexamethylindodicarbocyanine iodide (HIDC); and 3,3′-diethyloxadicarbocyanine iodide (DODC). This system can measure a large number of experimental points in a short time period. The effect of 32 various organic solvents on the UV-ViS spectra of the dyes was studied. The solvatochromic behaviour of studied dyes was characterized by positive solvatochromism for HIDC and negative solvatochromism for HIC and DODC. Through the application of a large number of experimental points, the protonation and hydrolysis constants of dyes were determined with high precision, where the confidence interval of the рK values is ±(0.001–0.005), compared with a confidence interval of ±(0.04–0.10) for standard procedures. The fully automated system presented is accurate, fast, environmentally friendly and promising for multiple analytical applications.

Solute dynamics in block-copolymer reverse micelles: do water content and copolymer concentration alter the microenvironment?

Solute dynamics has been explored in reverse micelles formed with the triblock copolymer (EO)13-(PO)30-(EO)13 (L64), where EO and PO represent ethylene oxide and propylene oxide units, respectively, with small amounts of water in p-xylene. To this effect, nonradiative rate constants (knr) and reorientation times (τr) of two carbocyanine derivatives, 3,3'-diethyloxadicarbocyanine iodide (DODCI) and merocyanine 540 (MC 540) have been measured at different mole ratios of water to copolymer (W) and also at three copolymer concentrations. By examining the nonradiative rate constants and the reorientation times of the two solutes, the microenvironment offered by L64/water/p-xylene reverse micellar system has been investigated. It has been observed that there is no variation in the nonradiative rate constants as well as in the reorientation times of both DODCI and MC 540 with an increase in W and [L64]. Since knr represents activated twist motion about the double bonds for these solutes, it is sensitive to the local friction and likewise, τr also provides information about the microenvironment. Thus, the results of this study indicate that DODCI and MC 540 are located in the cores of the L64 reverse micelles that are made up of hydrated ethylene oxide blocks and the hydration levels are not altered despite an increase in the water content and copolymer concentration. In other words, there is no variation in the microenvironment offered by L64/water/p-xylene reverse micellar system upon increasing W and [L64].

Photophysics of 3,3′-Diethyloxadicarbocyanine Iodide (DODCI) in Ionic Liquid Micelle and Binary Mixtures of Ionic Liquids: Effect of Confinement and Viscosity on Photoisomerization Rate

The dynamics of photoisomerization of 3,3'-diethyloxadicarbocyanine iodide (DODCI) has been investigated inside micellar environment formed by a surfactant-like ionic liquid, 1-butyl-3-methylimidazolium octyl sulfate ([C(4)mim][C(8)SO(4)]) and also in binary mixture of another ionic liquid, N,N,N-trimethyl-N-propyl ammonium bis(trifluoromethanesulfonyl) imide, ([N(3111)][Tf(2)N]) with methanol, acetonitrile, and n-propanol by using steady-state and picosecond time-resolved fluorescence spectroscopy. The entrapment of DODCI into the [C(4)mim][C(8)SO(4)] micellar environment led to the enhanced fluorescence intensity along with ~13 nm red shift in the emission maxima. A sharp increase in the fluorescence quantum yield (Φ) and the lifetime (τ(f)) near the critical micelle concentration (cmc) range is observed followed by saturation at higher concentration. As a result of partitioning of the probe molecules in the micellar phase from water, the nonradiative rate constant (k(nr)) of DODCI decreases 2.7 times than in water. The retardation of isomerization rate is due to high microviscosity of the micellar system compared to bulk water. In order to understand how the rate of isomerization depends on polarity as well as viscosity, we have measured isomerization rate in neat [N(3111)][Tf(2)N] and its mixtures with polar solvents, like methanol, acetonitrile, and n-propanol. The addition of methanol and n-propanol increases the polarity, but viscosity of the medium decreases. The nonradiative rate constant that represents the rate of photoisomerization decreases with the addition of the polar solvent in [N(3111)][Tf(2)N]. Complete analysis of all the experimental results indicate that viscosity is the sole parameter that regulates the rate of photoisomerization. Temperature-dependent k(nr) are used to determine the activation energy (E(a)) in 100 mM [C(4)mim][C(8)SO(4)] solution and neat [N(3111)][Tf(2)N] system.

Photoisomerization dynamics of 3,3′-diethyloxadicarbocyanine iodide in ionic liquids: Breakdown of hydrodynamic Kramers model

Photoisomerization dynamics of 3,3'-diethyloxadicarbocyanine iodide (DODCI) has been examined in a series of 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides by measuring its fluorescence lifetimes and quantum yields. This study has essentially been undertaken to find out whether the process of photoisomerization of DODCI in ionic liquids is different compared to that observed in conventional solvents such as alcohols. Activation energy of the reaction has been attained with the aid of isoviscosity plots and was found to be 22 ± 3 kJ mol(-1), which is a factor of two higher compared to that obtained in alcohols. The significantly higher activation energy obtained in bis(trifluoromethylsulfonyl)imides compared to alcohols is probably due to the highly ordered nature of the ionic liquids, which hinders the twisting process. Kramers theory has been applied to understand the reduced isomerization rate constants in terms of solvent friction. As in case of alcohols, the isomerization data could not be explained by the Kramers model. However, a power law relation, which is a phenomenological functional form, could mimic the observed trend.

Characterizing interfacial friction in bis(2-ethylhexyl) sodium sulfosuccinate reverse micelles from photoisomerization studies of carbocyanine derivatives

Photoisomerization of two carbocyanine derivatives has been examined in bis(2-ethylhexyl) sodium sulfosuccinate (AOT) reverse micelles to understand the factors that govern this process in the interfacial region of organized assemblies. To this effect, fluorescence lifetimes and quantum yields of 3,3(')-diethyloxadicarbocyanine iodide and merocyanine 540 have been measured in AOT∕isooctane∕water and AOT∕cyclohexane∕water reverse micellar systems as a function of the mole ratio of water to the surfactant, W. The nonradiative rate constants, which have been identified as the rates of photoisomerization for these solutes, were obtained from the experimentally measured parameters. The steady rise and subsequent saturation observed in the nonradiative rate constants upon increasing W has been rationalized in terms of micellar packing. An inverse correlation has been obtained between the nonradiative rate constants and the critical packing parameter, indicating that the interfacial friction experienced by the solute molecule is essentially described by this parameter.

ChemInform Abstract: Photoisomerization of Cyanines. A Comparative Study of Oxygen- and Sulfur-Containing Species

We have compared the photoisomerization properties of two cyanine analogs, 3,3'-diethyloxadicarbocyanine iodide (DODCI) and 3,3'-diethylthiadicarbocyanine iodide (DTDCI). These two molecules are structurally similar, differing only in the presence of oxygen or sulfur at two heteroatom sites. Measurement of the radiative and nonradiative population relaxation kinetics of these molecules reveals a difference in their equilibrium geometries despite their outward similarities. We relate this difference to the steric constraints imposed by the oxygen and sulfur heteroatoms and to the occurrence of an excited state barrier predicted by semiempirical calculations of the ground- and excited-state isomerization surfaces for these molecules

Photoisomerization of cyanine derivatives in 1-butyl-3-methylimidazolium hexafluorophosphate and aqueous glycerol: Influence of specific interactions

Photoisomerization of two cyanine derivatives, 3,3(')-diethyloxadicarbocyanine iodide (DODCI) and merocyanine 540 (MC 540), has been investigated in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate and aqueous glycerol (93 wt % glycerol +7 wt % water) by measuring fluorescence lifetimes and quantum yields. The aim of this work is to understand how the rates of photoisomerization of DODCI and MC 540 are influenced by specific solute-solvent interactions besides the viscosity of the medium. For DODCI, it has been observed that the nonradiative rate constants, which represent the rates of photoisomerization, are almost identical in the ionic liquid and aqueous glycerol at given temperature, indicating that viscosity is the sole parameter that governs the rate of photoisomerization. In contrast, the photoisomerization rate constants of MC 540 have been found to be a factor of 2 higher in aqueous glycerol compared to the ionic liquid. The observed behavior is due to the zwitterionic character of MC 540, a consequence of which, the twisted state gets stabilized by the solute-solvent hydrogen bonding interactions in aqueous glycerol, thus lowering the barrier for isomerization.

Studies on fluorenscence resonance energy transfer between CdS nanoparticles and DOCAI dyes

The water-soluble CdS nanoparticles were synthesized in aqueous solution. A novel fluorescence resonance energy transfer (FRET) system with CdS nanoparticles as energy donors and 3,3′-diethyl-oxadicarbocyanine iodide (DOCAI) dyes as energy accepter has been developed.

Fluorescent quenching method for determination of trace hydrogen peroxide in rain water

A simple and sensitive fluorescent quenching method for the determination of trace hydrogen peroxide (H 2O 2) has been proposed to determine hydrogen peroxide in rain water sample. The method is based on the reaction of H 2O 2 with 3,3′-diethyloxadicarbocyanine iodide (DI) to form a compound which has no fluorescence in acetate buffer solution (pH 3.09). The maximum emission wavelength of the system is located at 604 nm with excitation at 570 nm. Under the optimal conditions, the calibration graph was obtained between the quenched fluorescence intensity and hydrogen peroxide concentration in the range of 5.0 × 10 −7 to 9.0 × 10 −4 mol L −1. The proposed method was applied to determine H 2O 2 in rain water samples, and the result was satisfactory. The mechanism involved in the reaction was also studied.

Photoisomerization of a Carbocyanine Derivative in the Reverse Phases of a Block Copolymer: Evidence for the Existence of Water Droplets

In an attempt to understand the nature of water present in the reverse phases of aggregates formed with the triblock copolymer poly(ethylene oxide)(20)-poly(propylene oxide)(70)-poly(ethylene oxide)(20) (P123) and also investigate how these confined environments influence the rates of photoisomerization, fluorescence lifetimes and quantum yields of a carbocyanine derivative--3,3'-diethyloxadicarbocyanine iodide (DODCI)--were measured in these systems over the temperature range of 293-318 K. Three different copolymer-oil-water compositions were chosen such that the mole ratio of water to copolymer (W) spans the range of 50-150. In these systems, butyl acetate was used as the oil or the nonpolar component. It has been noticed that in all three systems the fluorescence decays of DODCI comprise a long component whose contribution is 85-90%, and this has been ascribed to the fraction of solute solubilized in the core region where hydrated poly(ethylene oxide) units are present. A short-decay component is associated with the remaining fraction, and its values match with those measured in water, indicating that the water present in these reverse phases is in the form of droplets. The photoisomerization rate constants of DODCI located in the core regions of the reverse phases are identical in the three systems at a given temperature and similar to the ones obtained in normal phases of P123. The reasons for the observed behavior have been discussed.

Polyene photoisomerization rates: Are they distinct in aqueous block copolymer micellar solutions and gels?

Photoisomerization of 3,3'-diethyloxadicarbocyanine iodide (DODCI) has been investigated in water, 5% and 30% aqueous triblock copolymer, poly(ethylene oxide)20-poly(propylene oxide)70-poly(ethylene oxide)20 (P123) by measuring the fluorescence quantum yields and lifetimes in the temperature range 293-318 K. Reports available in literature indicate that 5% aqueous P123 exists as micellar solution, whereas 30% aqueous P123 forms gel due to micelle-micelle entanglement. This study has been undertaken to find out how the polyene photoisomerization rates are influenced in the sol and gel phases. It has been observed that 60%-70% of DODCI is located in the palisade layer of the micelles in the sol as well as gel phases and the photoisomerization rate of this component is identical in both the phases at a particular temperature. The remainder of the probe is located in the interfacial region and isomerization rates of this fraction are slower by a factor of 1.4-1.1 in the gel phase compared with the micellar solution. The retardation of the isomerization rate in the gel phase has been explained on the basis of enhancement in the friction experienced by the probe due to micelle-micelle entanglement at the interface. Compared to the isomerization rates in water, the rates of photoisomerization of DODCI located in the palisade layer, interfacial region of micellar solution, and interfacial region of the micelles in the gel phase are slower by factors of 3.5, 1.5-1.9, and 2, respectively. The outcome of this study validates the point that in organized media photoisomerization rates are sensitive to the localized friction, which is not uniform unlike in a homogeneous solution.

Transient second-harmonic generation in a cyanine liquid dye solution

We investigate the second-harmonic generation induced by performing transient all-optical poling in a solution of the cyanine dye 3,3′-diethyloxadicarbocyanine iodide (DODCI). Second-harmonic generation demonstrates that the DODCI dye associated with its iodide counter ion is noncentrosymmetric. Polarization analysis of the process reveals that the iodide counter ion may be located at one of the extremities of the polymethine molecule, along its main axis. Interestingly, we show that the noncentrosymmetric supramolecular assembly is favored in low polarity solvents.

Transition-moment directions of selected carbocyanines from emission anisotropy and linear dichroism measurements in uniaxially stretched polymer films

Based on the Kawski–Gryczyński method the values of angle between absorption and fluorescence transition moments of carbocyanines are given. This method is applied to the linear molecules: 3,3′-diethylthiacyanine iodide (DTTHCI), diethyloxacarbocyanine iodide (DOCI), 3,3′-diethyl-9-methylthiacarbocyanine iodide (MDTCI), diethylthiacarbocyanine iodide (DTCI) and 3,3′-diethyloxadicarbocyanine iodide (DODCI). Similarly located transition moments polarized approximately along the long axis of DTTHCI, DOCI, MDTCI, DTCI and DODCI are responsible for absorption and fluorescence ( β ⩽ 10°), when exciting in the long wavelength absorption band. The results are compared with relevant data obtained from linear dichroism measurements, energy migration data in partly ordered films and general Perrin formula.

Dynamics of photoisomerisation and rotational relaxation of 3,3′-diethyloxadicarbocyanine iodide in room temperature ionic liquid and binary mixture of ionic liquid and water

The dynamics of photoisomerisation and rotational relaxation of 3,3′-diethyloxadicarbocyanine iodide (DODCI) in room temperature ionic liquid (IL) and binary mixture of IL and water are investigated using steady state and time resolved fluorescence spectroscopy. The photoisomerisation rate of DODCI is drastically retarded in room temperature IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6]) compared to isopolar solvent. The rotational relaxation time of the same dye is much slower in IL compared to the isopolar conventional solvent and become faster in presence of traces amount of water. The activation energy for photoisomerisation in different media (IL and IL-water) is also determined.

Fluorescence of CdSe/ZnS quantum dots in solid solutions in the presence of organic molecules DODCI

Fluorescence characteristics of solid solutions of CdSe/ZnS quantum dots (donor) and organic dye 3,3′-Diethyloxadicarbocyanine iodide (acceptor) in polymethylmetacrylate films have been investigated. The fluorescence intensity increase caused by the exciting radiation at the frequency of the QD absorption has been found for the films containing both QDs and DODCI. The abrupt rise of the fluorescence polarization degree has been observed at the high-frequency edge of the radiation spectrum of these films. Possible processes (nonradiative electronic excitation energy transfer, acceptor photodegradation) accounting for the experimental dependences are also discussed.

A G-Quadruplex Ligand 3,3′-Diethyloxadicarbocyanine Iodide Induces Mitochondrion-Mediated Apoptosis But Not Decrease of Telomerase Activity in Nasopharyngeal Carcinoma NPC-TW01 Cells

The G-quadruplex ligand 3,3'-diethyloxadicarbocyanine iodide (DODC) was reported to enhance the apoptotic potency of pheochromocytoma PC-12 and leukemia HL-60 cells through the inhibition of telomerase activity. In this study, a mitochondrion-mediated apoptotic pathway was demonstrated as another cytotoxic mechanism for DODC action. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and DNA laddering assays were performed to exhibit the cytotoxicity and apoptosis-inducing activity of DODC. Telomeric repeat amplification protocol (TRAP) assay was used to evaluate the effect of DODC on cellular telomerase. The mitochondrial uptake of probe 3,3'-dihexyloxacarbocyanine iodide was measured by flow cytometry. The mitochondrial proteomes were analyzed by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Western blot analyses were adopted to demonstrate the change of the distribution of mitochondrial proteins. DODC alone was able to induce apoptotic cell death but not decrease of telomerase activity in nasopharyngeal carcinoma NPC-TW01 cells. Instead, we found evidence that DODC significantly affected cellular mitochondria. DODC inhibited the uptake of another mitochondrial probe 3,3'-dihexyloxacarbocyanine iodide. By proteomic comparative analysis, we found that DODC induced the increase of prohibitin level in the mitochondria, indicating the occurrence of mitochondrial perturbation. Moreover, DODC was found to induce the levels of p53 and an 18-kDa truncated Bax on mitochondria, which in turn potentiated the release of cytochrome c for activation of caspases. DODC induces NPC-TW01 cell apoptosis via a mitochondrion-mediated mechanism. This paper demonstrates another cytotoxic mechanism of DODC other than inhibition of telomerase.

Principal component analysis of dual-luminophore pressure/temperature sensitive paints

Multi-luminophore pressure/temperature sensitive paints are investigated using principal component analysis of the spectral emission from the coatings. Two formulations are investigated. The first consists of Ru (4,7-diphenylphenanthroline) dichloride (Ruphen) and Coumarin-7 luminophores. The second coating contains Pt(II) meso-tetrakis (pentafluorophenyl) porphine (PtTFPP) and diethyloxadicarbocyanine iodide (DOCI). The principal component analysis revealed that the Ruphen/Coumarin-7 coating requires three fundamental spectra or modes to adequately model the coating emission characteristics. The PtTFPP/DOCI coating was modeled adequately with only two modes. Analysis of the PtTFFP/DOCI coating also revealed that a temperature independent calibration of the pressure sensing function could be developed. The requirement for a wind-off reference image was also eliminated.