Promising near-infrared non-targeted probes: benzothiazole heptamethine cyanine dyes

A series of benzothiazole heptamethine cyanine dyes have been synthesized and their photophysical properties evaluated in relation to their structural features. These have been compared against two classical probes of this type: Indocyanine Green (IGC) and New Indocyanine Green (IR-820). Growth inhibitory studies were also performed using a eukaryotic, unicellular organism, fission yeast Schizosaccharomyces pombe. Herein we highlight some potentially interesting candidates with improved fluorescence quantum yields when compared with ICG and IR-820.     

Some phthalazin derivatives as non toxic corrosion inhibitors for copper in sulphuric acid

Phthalazin derivatives were tested as corrosion inhibitors of copper in 1 M H₂SO₄ using electrochemical polarization and weight loss techniques. This study monitored the evolution of the inhibitory effect of the phthalazin derivatives, according to their substituents. A significant decrease in the corrosion rate of copper was observed in the presence of the investigated inhibitors. The inhibition efficiency (%I) increases with increasing inhibitor concentration. The potentiodynamic polarization data indicated that, the inhibitors were of mixed type, but the cathodic effect is more pronounced. The slopes of the cathodic and anodic Tafel lines are approximately constant and independent on the inhibitor concentration. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors. The adsorption on the copper surface follows the Langmuir isotherm model.     

Evaluation of non-toxic corrosion inhibitors for copper in sulphuric acid

The aim of this paper is to study influence of the molecular structure on the inhibiting properties of organic compounds in corrosion processes in acid media. The inhibiting efficiency of non-toxic imidazole derivatives on copper corrosion in sulphuric acid is investigated. The investigation is performed using electrochemical methods of potentiodynamic polarisation as well as gravimetric measurements. The results of the investigation show that the inhibiting properties of substituted imidazoles depend on molecular structure. The best protection (93%) is obtained by adding a phenyl ring to the imidazole structure. The values of standard free energies of adsorption, as calculated from the Freundlich isotherm, indicate that in the presence of sulphuric acid imidazole derivatives adsorb on copper by a physisorption-based mechanism.     

Synthesis,spectral behaviour and biological activity of pyrazolo-pyrimidine cyanine dyes

New asymmetrical 2(4)-monomethine cyanine dyes (III_a-_c IV_a-_i), monomethine bases (V_a,b), dicationic cyanines (VIII_a__c, IX_a-_c) and styryl cyanines (XI_a-_b) incorporating N-phenyl-1-H-pyrazolo (3, 4-d) saturated or unsaturated pyrimidine were prepared. The new cyanines were identified by spectral determination. Bactericidal and fungicidal activity of selected cyanines (III_a-c, IV_a-i, V_a,bVIII_a-_c, IX_a-c and XI_a,b) were tested against bacterial and fungal strains.     

菁染料在生物医学中的应用研究进展

菁染料的研究已有100多年的历史,目前其应用主要集中在非线性光学材料、光谱增感剂、光盘存储材料等方面。随着科学技术的发展,各学科的交叉和融合以及人们对菁染料性质的深入认识,菁染料已被应用于核酸及蛋白质分析测定、大分子标记、肿瘤检测、癌细胞识别、光动力疗法等方面。主要就2000年以来菁染料在生物医学方面的应用作一简单综述。     

Synthesis of novel monomeric cyanine dyes containing mercapto and thioacetyl substituents for nucleic acid detection

Fifteen novel mono-, di- and tricationic monomeric monomethine cyanine dyes, bearing mercapto and thioacetyl substituents, useful for nucleic acid detection are described. All derivatives absorb in the region 417–508 nm and have molar absorptivities of 61 000–101 300 l mol⁻¹ cm⁻¹. The products were characterized by ¹H NMR, HPLC–MS and elemental analysis.     

Study of different triazole derivative inhibitors to protect copper against pitting corrosion

Electrochemical experiments were performed to study the inhibitive effect towards copper corrosion of three organic compounds: namely, benzotriazole, 1-hydroxybenzotriazole and 3-amino 1,2,4-triazole. Statistical analysis of pit nucleation times showed that 3-amino 1,2,4-triazole exhibited the most significant inhibitive effect towards pitting. However, impedance measurements revealed that this compound produced a thinning of the passive film. This was corroborated by X-ray photoelectron spectroscopy. Results showed that copper pitting resistance could not be explained only by characterizing the protectiveness of the passive film.     

Pitting corrosion of copper in sulphate solutions: inhibitive effect of different triazole derivative inhibitors

The inhibitive effect of 3-amino 1,2,4-triazole (ATA) on the pitting corrosion of copper induced by sulphate ions was compared to that obtained with benzotriazole (BTAH) and 1-hydroxybenzotriazole (BTAOH) and to previous results obtained in chloride media. It was concluded that the inhibitive action of these compounds towards pitting corrosion was dependent on the aggressive species. For BTAH and BTAOH, the inhibitive efficiency was greater towards pitting induced by sulphate than towards pitting induced by chloride which was explained by referring to the surface area covered by the organic molecules and to the size of the aggressive species. For ATA, an opposite behaviour was observed and was explained by quantum chemical calculations. First, the binding energy between clusters of Cu⁺ ions and Cl^– was much weaker than that between clusters of Cu⁺ ions and SO₄^2–. Secondly, the adsorption of Cl^– on ATA linked to copper ions was more favourable than its adsorption on copper oxide. Moreover, the sulphate ion had a larger adsorption energy on copper ions than on ATA linked to copper ions.     

Microwave-assisted solvent-free synthesis and spectral properties of some dimethine cyanine dyes as fluorescent dyes for DNA detection

A series of dimethine cyanine dyes were synthesized in a fast, efficient and high yield by the condensation of quaternary salts with 1H-indole-3-carbaldehyde in the presence of piperidine under solvent-free microwave irradiation. The products were identified by ¹H NMR, IR, UV–vis spectroscopy and elemental analysis. The absorption and fluorescence properties of the dyes in both the free state and DNA or BSA were investigated. Significant enhancement of the fluorescent quantum yield was observed for all the dyes in the presence of DNA, with one compound demonstrating excellent sensitivity as a fluorescent probe.     

Electrochemical study of 2-mercaptoimidazole as a novel corrosion inhibitor for steels

From electrochemical methods, polarization resistance and electrochemical impedance spectroscopy, the corrosion susceptibility of pipeline steel samples immersed in 1 M H₂SO₄ was determined using nil and different concentrations of the molecule 2-mercaptoimidazole (2MI). It was found that a corrosion inhibiting efficiency, IE, value of 98.5% was reached when the 2MI concentration in the system increased to 25 ppm. Moreover, at this concentration, the 2MI IE was measured as a function of time finding that the IE kinetics follows the relationship: %IE = 98.5 − 0.03t after 800 h of evaluation. During the first 200 h 2MI IE was higher that 90% then, it decreased to 70% and it remained constant up to 1200 h. It is shown that this compound can affect both the anodic and cathodic processes, thus it can be classified as a mixed-type inhibitor however, from variation of both corrosion potential and polarization resistance with [2MI] it was possible to state that the anodic reaction rate, of the corrosion process, decreases at a greater proportion than the cathodic one. 2MI follows an adsorption mechanism, which can be adequately described by the Langmuir isotherm with an adsorption standard free energy difference (ΔG°_ads) of −26.8 kJ mol⁻¹. In order to analyze the influence of substituting groups, both electron-donating and electron-attracting and the number of π-electrons on the corrosion inhibiting properties of organic molecules, an electrochemical study was carried out on four different molecules having similar chemical framework structure: 2-mercaptoimidazole (2MI), 2-mercaptobenzoimidazole (2MBI) 2-mercapto-5-methylbenzimidazole (2M5MBI) and 2-mercapto-5-nitrobenzimidazole (2M5NBI). It was found that the IE order followed by the molecules tested was 2MI > 2MBI > 2M5MBI > 2M5NBI. Thus 2MI turned out to be the best inhibitor, even superior to the 2MBI. This fact strongly suggests that, contrary to a hitherto generally suggested notion, an efficient corrosion inhibiting molecule does not require to be a large one, also bearing an extensive number of π-electrons.     

Electrochemical and surface analysis study of copper corrosion protection by 1-propanethiol and propyltrimethoxysilane: A comparison with 3-mercaptopropyltrimethoxysilane

The inhibition of Cu corrosion by 1-propanethiol (1-PT) and propyltrimethoxysilane (PTS) molecules, in 0.100 mol L^–1 KCl solution, was investigated and compared to 3-mercaptopropyltrimethoxysilane (MPS). Corrosion inhibition was studied as a function of the 1-PT and PTS concentration in ethanol, between 1.0 × 10^–7 mol L^–1 and 1.0 × 10^–2 mol L^–1. Inhibition efficiency was calculated from Tafel plots in 0.100 mol L^–1 KCl solution. It improved with an increase in 1-PT or PTS concentration. The maximum efficiency was obtained at a 1-PT or PTS concentration of 1.0 × 10^–3 mol L^–1 or 1.0 × 10^–5 mol L^–1, respectively. Adsorption of 1-PT and PTS on copper followed a Langmuir behaviour. Potentiostatic polarization measurements indicated that 1-PT and PTS are mixed anodic/cathodic inhibitors, in the presence of dissolved oxygen. When the inhibitor exposure time of the pretreated Cu surface in 0.100 mol L^–1 KCl solution was varied, a loss on the corrosion inhibition efficiency was observed for the three (MPS, PTS and 1-PT) compounds. However, the 1-PT compound maintained excellent protection in the first 12 h of exposure to a 0.100 mol L^–1 KCl solution; afterwards, there was a significant loss in the inhibition efficiency. Surface analysis studies with Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) showed that the inhibitors modified the Cu surface.     

Experimental and atomistic simulation studies of corrosion inhibition of copper by a new benzotriazole derivative in acid medium

The efficiency of N-(2-thiazolyl)-1H-benzotriazole-1-carbothioamide (TBC) as a non-toxic corrosion inhibitor for copper in 0.5 M HCl has been tested by weight loss and electrochemical techniques. Electrochemical techniques show that TBC is a mixed-type inhibitor and its inhibition mechanism on copper surface is adsorption assisted by H-bond formation. Impedance measurements show a wide peak presumably given by more than one time constant in the presence of TBC. Also, impedance results show that the values of CPEs (constant phase elements) tend to decrease and both polarization resistance and inhibition efficiency tend to increase with increasing of TBC concentration due to an increase in the electric double layer. Monte Carlo simulations incorporating molecular mechanics and molecular dynamics show that the TBC adsorb on the copper surface firmly through the thiazolyl and carbothioamide groups, the adsorption energy as well as hydrogen bond length have been calculated for both TBC and benzotriazole (BTA) for comparison. Quantum chemical calculations reveal that TBC has higher HOMO, lower LUMO, lower energy gap and lower dipole moment (μ) than BTA, which proves that TBC is better copper corrosion inhibitor compared with BTA in 0.5 M HCl.     

Electrochemical and DFT studies of β-amino-alcohols as corrosion inhibitors for brass

The electrochemical performance of 1-diethylamino-propan-2-ol (EAP) and 1,3-bis-diethylamino-propan-2-ol (DEAP) for brass in simulated atmospheric water is evaluated by potentiodynamic curves and electrochemical impedance spectroscopy (EIS). The experimental results show that the investigated compounds, which can effectively retard the anodic dissolution of brass, are anodic inhibitors. Furthermore, the inhibition efficiency of DEAP is higher than that of EAP at the same concentration. This observation is supported by density functional theoretical (DFT) parameters such as the highest occupied molecule energy level (E_HOMO), the lowest unoccupied molecule energy level (E_LUMO), the energy difference (ΔE) between E_HOMO and E_LUMO, Mulliken charges and the HOMO orbital.     

Preparation of monomethine cyanine dyes as noncovalent labels for nucleic acids

By condensation of quaternary benzothiazolium, quinolinium and acridinium salts having an active methyl group with 1-(3-bromopropyl)-4-chloroquinolinium or 1-(3-bromo-2-hydroxypropyl)-4-chloroquinolinium salts in the presence of a basic agent such as triethylamine, 8 asymmetric and symmetric monomethine cyanine dyes bearing ω-bromopropyl substituent with one or two positive charges, were synthesized. Additionally, two of the dyes were quaternized with pyridine, and monomethine cyanines with two and three positive charges are prepared. Most of the dyes showed high molar absorptivity (70 000–100 000 l mol⁻¹ cm⁻¹). The acridinium dyes showed broad peaks with lower intensity of 30 000 l mol⁻¹ cm⁻¹. In the presence of nucleic acid in aqueous solutions, a strong enhancement of the fluorescence of these new dyes was observed.     

Polymeric corrosion inhibitors for copper and brass pigments

Copper and brass pigments corrode in aqueous alkaline media with the absorption of oxygen that can be measured gasvolumetrically. These corrosion reactions can be inhibited by certain polymers; the metallic sparkle and the color of the pigments is preserved. The brass pigment is inhibited more effectively than the copper pigment. Some low‐molecular mass styrene–maleic acid (SMA) copolymers are efficient corrosion inhibitors; a low acid number is necessary but not sufficient for corrosion inhibition. At pH 8.5 there is a potential correlation between the acid number of the low‐molecular mass SMA and the oxygen volumes absorbed from brass pigment dispersions; oxygen volumes decrease with decreasing acid number. Furthermore, increasing copolymer addition effects an increase of corrosion inhibition. Polyacrylic acids, polyvinyl alcohols and high‐molecular mass SMA copolymers are ineffective. The most efficient group of polymers examined in this study are the styrene–acrylate copolymers because by addition of these the overall lowest volumes of oxygen were absorbed by the metal pigments. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 475–483, 2001     

A NIR Emitting Cyanine with Large Stokes’ Shift for Mitochondria and Identification of their Membrane Potential Disruption

An NIR emitting (λ_em≈730 nm) cyanine probe ExCy was synthesized in good yields by extending the π-conjugation length (i. e., with furan moiety) to the donor-accepter system. ExCy exhibited a large Stokes’ shift (Δλ≈100 nm) due to strong intramolecular charge transfer (ICT), and high fluorescence quantum yield (Φ_fl≈0.47 in DCM). Due to its low fluorescence in an aqueous environment (Φ_fl≈0.007 in H₂O), the probe exhibited the potential of achieving a large fluorescence turn-on upon entering a hydrophobic cellular environment. Fluorescence confocal microscopy studies revealed that ExCy was readily excitable with a far-red laser line (i. e., 640 nm) while the corresponding emission was collected in the NIR region. ExCy exhibited excellent selectivity towards live cell mitochondria according to the co-localization studies. The probe also exhibited high photostability, long-term imaging ability and wash-free staining ability, when being applied to live cells. Our studies indicated that the mitochondrial localization of ExCy was dependent on the membrane potential of the mitochondria. ExCy was successfully utilized as a mitochondrial membrane potential dysfunction indicator to visually identify cells with mitochondrial dysfunction via fluorescence confocal microscopy. ExCy was further examined for potential in vivo imaging of zebrafish.     

Mercapto functional azole compounds as organic corrosion inhibitors in a polyester-melamine coating

The corrosion inhibition of two mercapto functional azole compounds including 2-mercaptobenzimidazole (MBI) and 2-mercaptobenzoxazole (MBO) for mild steel in 1 M NaCl solution was studied by electrochemical impedance spectroscopy (EIS), then their impact on the protective performance of a polyester-melamine coating was evaluated using salt spray. EIS results revealed a higher corrosion inhibitive activity of MBI compared to that of MBO. Corrosion products were examined by SEM-EDX and FTIR. The results showed modification of the corrosion products in the presence of MBI and MBO. The salt spray results revealed an improved corrosion protection of the coatings formulated with MBI and MBO. There was almost no impact of MBI and MBO on adhesion strength and glass transition temperature of the coatings, meaning that their impact on the corrosion protection performance of the formulated coating could only be attributed to their effect on the corrosion products.     

Some environmentally friendly formulations as inhibitors for mild steel corrosion in sulfuric acid solution

The corrosion resistance of mild steel in 1 M H₂SO₄ solution was evaluated after addition of Sn²⁺ and Zn²⁺, N-acetylcystein (ACC) and S-benzylcystein (BzC) as a function of concentration (5–1000 μM) and solution temperature (35–50°C). Eight blends were also investigated. Both polarization resistance (R _p) and electrochemical impedance spectroscopy (EIS) were employed. For single additives, Zn²⁺ ions acted as accelerator for mild steel corrosion while the other additives showed good performance. The most effective additive was Sn²⁺. Adsorption of Sn²⁺, ACC and BzC obeyed the Temkin adsorption isotherm and had a very high negative value of free energy of adsorption (−ΔG°_ads). All blends provided good inhibition which increased with rise in temperature. Corrosion kinetic parameters such as activation energy (E _a) and the pre-exponential factor (λ) were calculated and discussed. EIS revealed that the interface of the uninhibited and inhibited systems can be represented by the simple equivalent circuit R _e(R _ct Q _dl).     

Electrochemical corrosion properties of metal alloys used in orthopaedic implants

This study concerns an investigation of the corrosion behavior of 316 stainless steel, CoCrMo and Ti6Al4V alloys in simulated body conditions (ringer lactate) at 37 °C by the use of Tafel plots, mixed potential and electrochemical impedance spectroscopy (EIS). Ti6Al4V alloy has the highest corrosion resistance followed by CoCr alloy. Ti6Al4V–CoCrMO was the best couple for galvanic corrosion with the minimum galvanic potential and current values according to mixed potential theory and Tafel method. It was concluded that Ti6Al4V was the most suitable material for implant applications in the human body.     

1,2,3-苯并三氮唑铜缓蚀剂的研究进展

苯并三唑(BTAH)是一种非常有效的铜及其合金的缓蚀剂。到目前为止有许多关于BTAH缓蚀作用的研究,但其缓蚀机制仍然不为所知。对BTAH的缓蚀研究作出了总结,以便为进一步研究和开发新的高效缓蚀剂提供依据。