Pink Solution Research Articles

Synthesis and X-ray studies of ruthenium(II) complexes containing hydrazine and benzyl isocyanide ligands

The reaction of the polymeric species [{RuCl2(COD)}x] (1; x > 2; COD = cyclo-octa-1,5-diene) and hydrazine hydrate in methanol under reflux gave a pale pink solution from which the salt [Ru(COD)(N2H4)4][BPh4]2.CH3OH (2) was isolated on addition of NaBPh4. Treatment of 2 in refluxing acetone in the presence of the ligand benzyl isocyanide give a complex of stoichiometry [Ru(NH2N=CMe2)2(PhCH2NC)4][BPh4]2 (3) on the substitution of the labile COD ligand. The two compounds have been characterized by elemental analyses, IR and NMR measurements and single-crystal X-ray diffraction studies. The ruthenium in both compounds has a distorted octahedral coordination geometry. KEY WORDS: Cycloocta-1,5-diene, Hydrazine hydrate, Isocyanide, Ruthenium Bull. Chem. Soc. Ethiop. 2013, 27(3), 405-411.DOI: http://dx.doi.org/10.4314/bcse.v27i3.9

Development of formaldehyde detection method using onion juice as chromogenic agent

This work reports an initial study on the use of natural compound, i.e. onion juice, as a novel environmental-friendly chromogenic agent to determine the concentration of formaldehyde. The method is based on the reaction of formaldehyde with yellow onion juice to produce a pink solution which absorb strongly at 514 nm. Factors affecting the extent of reaction between formaldehyde and onion juice such as temperature, pH of onion juice and reaction time were optimized using the response surface methodology approach via the Box–Behnken design. The experimental values obtained were close to the predicted values indicating good approximation of the model. The optimum response was obtained by heating the onion juice at 60°C, pH 4.9, reaction temperature of 103°C and reaction time of 17 min. A linear calibration curve was obtained using formaldehyde concentrations ranging from 0.5 to 15 mg L−1. This study demonstrates the potential application of onion juice as a simple, safe and environmental friendly technique for quantitative determination of formaldehyde from various sources such as drinking water and aquaculture products.

1,4-Dihydroxyanthraquinone–Cu2+ ensemble probe for selective detection of sulfide anion in aqueous solution

Based on the displacement strategy, a new and simple sulfide-selective chemosignaling system was devised using 1,4-dihydroxyanthraquinone (DHAQ)–Cu2+ ensemble. In aqueous solution containing 10% ethanol (HEPES buffer, pH7.4), DHAQ could give rise to a visible yellow-to-pink color change with the addition of Cu2+. The resulting pink solution changed to yellow upon subsequent addition of sulfide anion. Moreover, DHAQ displays an “ON–OFF–ON” mode fluorescence change with alternately added Cu2+ and S2−. Experimental results show a low interference response towards other common anions. The selective switch-on fluorescence response of the sensing ensemble to S2− makes it suitable for sensing of S2− in aqueous solution. The detection limit is 5.98 × 10−8 M.

Ceramic pigments based on chromium doped alkaline earth titanates

In this paper M(Ti 1− x Cr x )O 3 with M=Mg, Ca, Sr, Ba and x =0.01, 0.03, 0.05, 0.1 compositions have been prepared by solid state reaction in order to analyze their reactivity, structure, limit of solid solution, stability and pigmenting properties in conventional ceramic glazes. Cr–MgTiO 3 crystallizes magnesium ilmenite MgTiO 3 (SG=R-3) with residual MgCr 2 O 4 spinel that inhibits the Cr entrance in solid solution and do not show pigmenting properties. Cr–CaTiO 3 crystallizes orthorhombic perovskite (SG=Pbnm) pink solid solutions associated to Cr 4+ –Ti 4+ substitutions which above x =0.03 unstabilizes in glazes and produce light green shades. Cr–SrTiO 3 crystallizes ideal cubic perovskite (SG=Pm3m) pink solid solutions that unstabilizes in glazes above x =0.01. Finally Cr–BaTiO 3 crystallizes tetragonal perovskite (SG=P4mn) with residual peaks of BaCrO 4 at x =0.1 showing pink solid solutions until x =0.05 that unstabilizes in glazes above x =0.03. All powders show aggregates (between 2–10 μm of size) of fine particles (between 200–1000 nm).

Study of color change and microstructure development of Al 2O 3–Cr 2O 3/Cr 3C 2 nanocomposites prepared by spark plasma sintering

The densification behaviors of Al 2O 3–Cr 2O 3/Cr 3C 2 nanocomposites prepared by a Spark Plasma Sintering (SPS) were investigated in this work. The initial powders used for sintering were Al 2O 3–Cr 2O 3, which were prepared by metal organic chemical vapor deposition (MOCVD) in a spout bed. Different colors of the compacts such as green, purple and black were observed after densification process at different SPS temperatures from 1200 °C to 1350 °C. These changes of color were relevant to the existence of secondary phase of green Cr 2O 3, pink solid solution of Cr 2O 3–Al 2O 3 and black Cr 3C 2, which were formed under the different SPS temperature. The secondary phase of Cr 2O 3 retarded the processing of densification for spark plasma sintering at 1200 °C. The Cr 2O 3 reacted with Al 2O 3 to form solid solution of Cr 2O 3–Al 2O 3 and with carbon to form Cr 3C 2 as sintering temperature increased to 1350 °C. The characteristics of high heating rate, shorter sintering time for SPS and the formation of secondary phase of Cr 3C 2 effectively reduced the substrate's grain growth, making Al 2O 3–Cr 2O 3/Cr 3C 2 nanocomposites with small grain size.

Novel molecular detection of Cu2+ in aqueous solution and related chemistry

Rationally-designed sensors for the detection and measurement of Cu2+ continue to receive significant attention. Cu2+ is an essential d-block metal ion in human health, but is also harmful to biological systems in excessive amounts. Alterations in Cu2+ cellular homeostasis are connected to Wilson's Disease and Alzheimer's Disease. Accordingly, the development of Cu2+-specific molecular probes have been of considerable interest in the biological and analytical chemical sciences. While there are various reports that explore Cu2+-selective probes, very few reports involved studies in pure aqueous solution. Herein, we report: I. the synthesis and characterization of the fluorescent dinuclear chiral compound [Zn2(slys)2Cl2] and also [Zn2(slys)2(NO3)2] [H2slys = 6-amino-2-{(2-hydroxybenzylidene) amino}hexanoic acid] II. Rigid indacene-like “BODIPY”-type species are commonly used as fluorescent probes, dyes, and pigments in biological imaging and as molecular sensing components. We are investigating how novel multiple 2- / 3-thienyl substitution imparts UV-vis absorption / emission differences. We have synthesized the isomeric probes: 3-(thienyl)-4,4-di(thienyl)-8-(thienyl)-4-bora-3a,4a-diaza-s-indacenes. I. [Zn2(slys)2Cl2] and also [Zn2(slys)2(NO3)2] [H2slys = 6-amino-2-{(2-hydroxybenzylidene) amino}hexanoic acid] were prepared by a one-pot in situ process. They are isolated with solvents of 1·(CH3OH)2·(H2O)3, and 2·(H2O)3, respectively. II. We have also prepared 3-(thienyl)-4,4-di(thienyl)-8-(thienyl)-4-bora-3a,4a-diaza-s-indacenes with an interest in systematically discerning Mn+ recognition capabilities at a novel tri-thienyl receptor site. The thienyls mark a step away from the commonly used pyridyl groups or crowns for metal cation recognition. I. [Zn2(slys)2X2] engages in selective Cu2+ detection (over other metal ions, e.g.: Hg2+, Cd2+ and Pb2+) through direct displacement in water. Zinc, another metal of neurodegenerative interest is freed (displaced) in the transformation. II. The boron-dipyrrin derivatives 3-(thienyl)-4,4-di(thienyl)-8-(thienyl)-4-bora-3a,4a-diaza-s-indacenes form pink solutions and were treated with dilute concentrations of various Mn+ species in demonstrating selective differences for Cu2+ and Hg2+. Generally, Cu2+ gives fluorescence increases while Hg2+ gives fluorescence decreases; but, for the systems shown herein, there are a variety of optical changes via different mechanisms at low Cu2+ concentration (in various solvents). In particular, the treatment of 3-(2-thienyl)-4,4-di(2-thienyl)-8-(3-thienyl)-4-bora-3a,4a-diaza-s-indacene with Cu2+ gives a clear solution only and this probe may be a promising component in optical sensing.

Colorimetric Sensing of α-Amino Acids and Its Application for the “Label-Free” Detection of Protease

A new indirect approach to explore sensitive colorimetric sensors toward alpha-amino acids is proposed: the pink solution of 1 and copper ions changed to colorless immediately upon the addition of alpha-amino acids. As the hydrolysis of bovine serum albumin (BSA) with the aid of trypsin produces alpha-amino acids, the complex of 1/Cu(2+)/BSA could act as a label-free, sensitive, selective sensor toward trypsin. The detection process could be visually observed by naked eyes.

Forensic analysis of phenolphthalein-A Review

Although a number of different techniques using different chemicals such as fluorescent dyes, starch powder, phenolphthalein powders etc have been adopted but phenolphthalein powder in anticorruption cases has remained most popular in India. Phenolphthalein is a weak acid; its unionized molecules are colourles while on ionization give pink colour. The sodium carbonate washings containing traces of transferred phenolphthalein from accused is submitted to Forensic Science Laboratories (FSLs) for examination. There are so many conventional and instrumental techniques (Thin Layer Chromatography, UV-Visible Spectrophotometer, High Performance Liquid Chromatography, High Performance Thin Layer Chromatography etc.) which may be used for the confirmation of phenolphthalein. INTRODUCTION Phenolphthalein is being used in most of the anticorruption cases. Phenolphthalein powder, a smooth white powder is generally applied in small quantity on the currency notes and other objects are likely to come in contact with hands, pockets etc of the culprit resulting in its transfer (Locard’s principle of exchange). The object (hand, bag, pocket etc) are washed with a colorless solution of sodium carbonate (or sometimes with lime water), which becomes immediately pink confirming the touching of currency notes/ transferred of phenolphthalein to the object. Pink to deep red colour is developed depending upon the quantity of phenolphthalein involved. These washings are being collected and sent to the forensic laboratories along with other relevant materials for analysis. 2 CHEMISTRY OF PHENOLPHTHALEIN Phenolphthalein is a weak acid and is almost unionized. Its unionized molecules are colourless whilst on ionization give colourless H and pink coloured phenolphthalein ions. In the presence of acid due to increase in the concentration of common ions (H), the dissociation of phenolphthalein is suppressed and thus the solution becomes colourless. While the addition of strong bases (e.g. KOH, NaOH ) produces OH ions combine with the H+ ions from the phenolphthalein to form the ionized water. Thus more phenolphthalein ions are produced giving the pink colour solution.

Chemically-Tailored Surfaces of Silica Gel and Alumina Examined Using Color

Freshman students engaged in a three-session laboratory project attached functional group moieties bearing established chemical scavengers onto the surfaces of porous silica gels and alumina and assayed the tailored materials for their ability to remove specific agents out of protic solutions. The students deposited organosilanols featuring amine-type scavenger groups onto the starting materials, affording, in particular, surfaces tailored with (3-aminopropyl)silyl and {3-[2-(2-aminoethylamino)ethylamino]propyl}silyl moieties. The modified surfaces were succinylated thereafter, converting amino groups into succinamic acid derivatives and affording a second generation of scavengers. Chromogenic ninhydrin analyses confirmed the surface-pendant amino groups by a positive color-yield and the surface-pendant succinylated amino groups by a greatly reduced or negative color-yield. The students easily studied the interaction between engineered surfaces and solutions containing model acids, aldehydes, bases, and transition metals by virtue that each compound examined was inherently colored or color-yielding. The binding of glutaraldehyde was recognized by the development of a fixed orange color, while cupric ion was noted by various shades of blue. Surface-immobilized morpholine was noted by the development of a pink solution. Bromocresol green produced a dark blue surface, and potassium permanganate gave a rich violet color. In all cases, native silica gel remained colorless after similar treatments, implying that the surface properties of modified silica gel were markedly altered through rational design. The students concluded their project with a report, having experienced the merits of surface engineering and color-facilitated analyses.

Flower color affects tri-trophic-level biocontrol interactions

The adults of many parasitoid species require nectar for optimal fitness, but very little is known of flower recognition. Flight cage experiments showed that the adults of an egg parasitoid ( Trichogramma carverae Oatman and Pinto) benefited from alyssum ( Lobularia maritima L.) bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on all non-white flowers were no greater than when the parasitoids were caged on alyssum shoots from which flowers had been removed. The possibility that differences between alyssum cultivars were due to factors other than flower color, such as nectar quality, was excluded by dying white alyssum flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed alyssum flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower color appears, therefore, to be a critical factor in the choice of plants used to enhance biocontrol, and is likely also to be a factor in the role parasitoids play in structuring invertebrate communities.

Heat-set gel-like networks of lipophilic Co(II) triazole complexes in organic media and their thermochromic structural transitions.

A novel class of thermally responsive supramolecular assemblies is formed from the lipophilic cobalt(II) complexes of 4-alkylated 1,2,4-triazoles. When an ether linkage is introduced in the alkylchain moiety, a blue gel-like phase is formed in chloroform, even at very low concentration (ca. 0.01 wt %, at room temperature). The blue color is accompanied by a structured absorption around 580-730 nm, which is characteristic of cobalt (II) in the tetrahedral (T(d)) coordination. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) of the gel-like phase confirms the formation of networks of fibrous nanoassemblies with widths of 5-30 nm. The observed widths are larger than a molecular length of the triazole ligand (ca. 2.2 nm) and they are consisted of aggregates of T(d) coordination polymers. Very interestingly, the blue gel-like phase turned into a solution by cooling below 25 degrees C. A pale pink solution is obtained at 0 degrees C, indicating the formation of octahedral (O(h)) complexes. The observed thermochromic transition is totally reversible. The formation of gel-like networks by heating is contrary to the conventional organogels, which dissolve upon heating. Temperature dependence of the storage and loss moduli (G' and G") shows minima around at 27 degrees C, at which temperature they gave comparable values. On the other hand, G' exceeds G" both in the gel-like phase (temperature above 27 degrees C) and in the solution phase (temperature below 25 degrees C). These observations indicate that T(d) complexes are present as low-molecular weight species around at 25-27 degrees C. They are self-assembled to polymeric T(d) complexes by heating and form gel-like networks. Upon cooling the solution below 25 degrees C, T(d) complexes are converted to O(h) complexes and they also self-assemble into oligomeric or polymeric species at lower temperatures. The observed unique thermochromic transition (pink solution --> blue gel-like phase) is accompanied by an exothermic peak in differential scanning calorimetry (DSC), and is shown to be an enthalpy-driven process. The lipophilic modification of one-dimensional coordination systems provides unique solution properties and it would be widely applicable to the design of thermoresponsive, self-assembling molecular wires.

新しい自己組織化材料：一次元金属錯体を主鎖とするナノワイヤーの開発

The ability to manipulate nano to microscopic superstructures based on molecular self-assembly holds a key to develop future nanomaterials. In this review, the design and synthesis of self-assembling inorganic nanowires are introduced. First, lipophilic nanowires consisting of cationic, one-dimensional mixed valence PtII/PtIV complex and anionic lipids are developed. They display thermal dissociation and re-assembling characteristics and provide the first example of self-assembling conjugated nanowires. It also enables bottom-up manipulation of stereo-nanoarchitectures on solid surfaces. Second, heat-set gel-like networks are self-assembled from lipophilic Co (II) triazole complex in chloroform. It affords blue gel at room temperature, whose color is characteristic of the tetrahedral (Td) coordination structure. Upon cooling, the gel is dissolved into pale pink solution (Oh complex) and this change was thermally reversible. The reversible, heat-set gelation of organic liquids has been unprecedented. These new approaches and findings provide new dimensions in the fields of nano- and materials chemistry.

Rapid spot tests for detecting the presence of adulterants in urine specimens submitted for drug testing.

Several adulterants are used to mask tests for abused drugs in urine. Adulterants such as "Klear" and "Whizzies" contain potassium nitrite, and "Urine Luck" contains pyridinium chlorochromate (PCC). The presence of these adulterants cannot be detected by routine specimen integrity checks (pH, specific gravity, and temperature). We developed rapid spot tests for detecting these adulterants in urine. Addition of 3% hydrogen peroxide in urine adulterated with PCC caused rapid formation of a dark brown color. In contrast, unadulterated urine turned colorless when hydrogen peroxide was added. When urine contaminated with nitrite and 2 to 3 drops of 2N hydrochloric acid were added to 2% aqueous potassium permanganate solution, the dark pink permanganate solution turned colorless immediately with effervescence. Urine contaminated with nitrite liberated iodine from potassium iodide solution in the presence of 2N hydrochloric acid. Urine adulterated with PCC also liberated iodine from potassium iodide in acid medium but did not turn potassium permanganate solution colorless. Urine specimens from volunteers and random urine samples that tested negative for drugs did not cause false-positive results. These rapid spot tests are useful for detecting adulterated urine to avoid false-negative drug tests.

Kinetics and mechanism of oxidation of formic acid by bismuth(V) in aqueous phosphoric acid medium

The solution of bismuth(V) was prepared by digesting sodium bismuthate in aqueous phosphoric acid (3.0 mol dm−3), the resulting pink colour solution absorbs in the visible region at 530 nm (640 dm3 mol−1 cm−1). The stoichiometry of the oxidation of formic acid by bismuth(V) corresponds to the reaction as represented by the Eq. (1). (1)The observed kinetic rate law is given by the Eq. (2); (2)where BiV and [HCO2H] are the gross analytical concentrations of bismuth(V) and formic acid respectively. A plausible reaction mechanism corresponding to the rate law (2) has been proposed. Also the pattern of reactivity of bismuth(V) in HCIOHF mixture and H3PO4 respectively has been compared. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 491–497, 2000

Characterization of laser-irradiated C60 solution and cell damage by SEM,TEM and atomic-force microscopy

Investigation of laser irradiated purple C60/toluene solutions revealed a photochemical change of the solution at high incident laser fluences. The initial purple solution turned pink and a black precipitate formed which was insoluble in toluene. Interaction at the cell surface was indicated as cell damage occurred before the solution changes were seen. Subsequent chemical analysis by Mass Spectroscopy showed that the pink solution contained C60 and adducts. The black precipitate was found to contain no C60, but instead contained only adducts and lower fuller-enes NMR on the pink solution revealed a SiCHx peak as evidence of glass etching.Scanning electron microscopy revealed needle crystals from a pure C60 sample, in figure 1. Figure 2 shows the crystals from the pink solution. The black precipitate appears to have a porous,very grainy texture and lacks the crystalline structure of the other samples (figure 3). All three samples were deposited on carbon coated grids. The pyrex glass cell was damaged by the laser and showed an etching pattern (figure 4).

Carboxy-bound chromium(IV); a formal potential and estimated self-exchange rate for Cr III,IV pertaining to 2-ethyl-2-hydroxybutanoate chelates

Pink solutions containing a stabilized complex of CrIV result from reduction of HCrO4– with H3AsO3 in media buffered by 2-ethyl-2-hydroxybutanoic acid (Hehb); redox reactions of this atypical state lead to a calculated E° of 0.96 ± 0.02 V for CrIII,IV and an estimated self-exchange rate 10–2.6 ± 0.6 dm3 mol–1 s–1(25 °C, µ= 0.5 mol dm–3), the latter value supporting a six-coordinate structure of CrIV(ehb)2, rather than a five-coordinate CrIV(O) species.

An electron spin resonance and optical study of the behaviour of Cs2[TcNCl5] in hydrochloric acid solutions

Optical spectroscopy, magnetic susceptibility, and e.s.r. have been used to study the behaviour of Cs2[TcNCl5] in aqueous HCl solutions. In 5.6 mol dm–3 HCl the predominant species is the [TcNCl4]– anion (λmax 398 nm, Iµ 440 m2 mol–1) possibly with H2O weakly bound trans to the N atom. Addition of 1 volume of H2O to Cs2[TcNCl5] followed by 2 volumes of 5 mol dm–3 HCl gives a deep blue species (λmax. 558 nm, Iµ 393 m2 mol–1), which is converted to [TcNCl4]– on standing. Cs2[TcNCl5] dissolved in 0.5 mol dm–3 HCl gives a pink solution (λmax. 540 nm, Iµ 215 m2 mol–1) which is stable over several days. The magnetic susceptibility and e.s.r. measurements indicate that the blue and pink species are diamagnetic. Possible structures of the diamagnetic species are discussed by analogy to the behaviour of [MOX5]n– in solutions of varying acidity.

Simultaneous determination of choline and betaine in some fish materials

The assay of choline and betaine, as water-insoluble reineckate derivatives, has been adapted to the simultaneous determination of these two quaternary nitrogenous compounds. No preliminary column fractionation is required. The solution resulting from the initial extraction - hydrolysis stage is divided into two portions; one portion is adjusted to pH 1.0 and the other to pH 8–9 before the addition of ammonium reineckate. Under acidic conditions, choline and betaine reineckate are precipitated and at an alkaline pH only choline reineckate precipitates. The reineckate salts are re-dissolved in acetone to give pink solutions for spectrophotometric measurement at 526 nm. Choline reineckate has a higher linear absoptivity than betaine reineckate and this feature is allowed for by reference to the respective calibration graphs; the choline content of the extract is determined directly and the betaine content by difference. Model systems containing 2–3 mg of pure choline or betaine can be assayed but sample masses of 3–4 g of biological material are recommended for the analysis.

MAGNETIC EXCHANGE INTERACTION AND SPIN-STATE EQUILIBRIUM IN COBALT(II) COMPLEXES OF 1(2-PYRIDYLAZO)-2-PHENANTHROL

Abstract 1-(2-Pyridylazo)-2-phenanthrol forms two distinct complexes with cobalt(II). Isolation from ethanolic medium yields green coloured CoL2, · 4C2 HSOH, which shows antiferromagnetic interaction between cobalt(H) ions of S=1/2 (J=49 cm−1). The green coloured complex dissolves in chloroform to give a pink solution yielding pink crystals of CoL2 · 4C2 H5 OH · 1/3 CHCl3, which involves temperature dependent equilibrium between doublet (S=1/2) and quartet (S=3/2) states.

Formation of Baudisch complexes [FeII(CN)5,RNO]3–from alkyl- and aryl-hydroxylamines and aquapentacyanoferrate(3–) anions, [FeII(CN)5,H2O]3–

Aqueous sodium aquapentacyanoferrate(3–) reacts with phenylhydroxylamine at pH 7–10 under nitrogen to give the purple complex of Baudisch in approximate accord with equation (i). The free radicals PhNHO· and PhNH·[Fe(CN)5,H2O]3–+ 2PhNHOH =[Fe(CN)5,PhNO]3–+ PhNH2+ 2H2O (i) participate in the reaction process. Aliphatic hydroxylamines react similarly at pH 5–8 to give pink solutions containing analogous anions, of a type hitherto unknown except for the Legal complexes of aliphatic aldehydes and ketones. The reactions with aliphatic hydroxylamines are slower and more complex, rearrangements of alkylaminyl radicals being involved. Spectrographic and e.s.r. studies have been used to elucidate the mechanisms of these reactions.