Colored inks analysis and differentiation: a first step in artistic contemporary prints discrimination

Prints are the most popular artistic technique. Due to their manufacturing procedure, they are also one of the most frequently falsified types of artwork. In terms of their economic and historic value, the chemical analysis and characterisation of coloured inks and their principal constituent materials (pigments), together with the historical and aesthetic information available in the Catalogues Raisonées, are important tools in distinguishing originals from non-original prints.The chemical characterisation and discrimination of coloured inks has test in this study. Analysis using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray diffraction (XRD) has been done on blue pigments and inks, due to this colour is one of the most representative for the presence of organic and inorganic materials in their composition. Conclusion obtained for this colour would demonstrate the capability of the approach when it is applied to any other coloured set of inks.     

Analysis of organic solvents in printing inks by headspace gas chromatography – mass spectrometry

Static headspace analysis by gas chromatography has been found to be a suitable method for the analysis of organic solvents in printing inks. Experimental conditions for the analysis have been optimized, and the accuracy and relative standard deviation of the method has been determined. The solvent content of 29 printing inks has been measured.     

A multi-analytical approach for the characterization of powders from the Pompeii archaeological site

Nine black powders found in Pompeii houses in three different types of bronze vessels (cylindrical theca atramentaria, unguentaries, and aryballoi) were characterized in order to assess a correspondence between the composition and the type of vessel and, possibly, to verify if these powders were inks or not. For the compositional characterization, a multi-analytical approach was adopted, which involved the use of scanning electron microscopy-energy dispersive X-ray, Fourier-transformed infrared spectroscopy, Raman, X-ray diffraction, electron paramagnetic resonance spectroscopy, thermogravimetric analysis, gas chromatography coupled with mass spectrometry (GC/MS), and pyrolysis GC/MS. Powders contained in cylindrical theca atramentaria form a homogeneous group, and their organic and inorganic compositions suggest that they were writing inks, while powders contained in unguentaries and aryballoi could have had several different uses, including writing inks and cosmetics. Furthermore, the composition profile of the powders found in cylindrical cases shows that, at 79?AD: , in Pompeii, carbon-based inks were still used for writing, and iron gall inks had not been introduced yet.     

Wide‐Range Color‐Tunable Organic Phosphorescence Materials for Printable and Writable Security Inks

Organic materials with long‐lived, color‐tunable phosphorescence are potentially useful for optical recording, anti‐counterfeiting, and bioimaging. Herein, we develop a series of novel host–guest organic phosphors allowing dynamic color tuning from the cyan (502 nm) to orange red (608 nm). Guest materials are employed to tune the phosphorescent color, while the host materials interact with the guest to activate the phosphorescence emission. These organic phosphors have an ultra‐long lifetime of 0.7 s and a maximum phosphorescence efficiency of 18.2 %. Although color‐tunable inks have already been developed using visible dyes, solution‐processed security inks that are temperature dependent and display time‐resolved printed images are unprecedented. This strategy can provide a crucial step towards the next‐generation of security technologies for information handling.     

Chemometric tool for identification of iron–gall inks by use of visible–near infrared fibre optic reflection spectroscopy

A method has been developed for identification of corrosive iron–gall inks in historical drawings and documents. The method is based on target-factor analysis of visible–near infrared fibre optic reflection spectra (VIS–NIR FORS). A set of reference spectra was obtained from model samples of laboratory-prepared inks covering a wide range of mixing ratios of basic ink components deposited on substrates and artificially aged. As criteria for correspondence of a studied spectrum with a reference spectrum, the apparent error in target (AET) and the empirical function SPOIL according to Malinowski were used. The capability of the proposed tool to distinguish corrosive iron–gall inks from bistre and sepia inks was evaluated by use of a set of control samples of bistre, sepia, and iron–gall inks. Examples are presented of analysis of historical drawings from the 15th and 16th centuries and written documents from the 19th century. The results of analysis based on the tool were confirmed by XRF analysis and colorimetric spot analysis.

Scalable Preparation of Photochromic Composite Foils with Excellent Reversibility for Light Printing

Photochromic inks for repeatable light‐printed media have attracted increasing attention owing to the fact that they may be widely applied to reduce the consumption of papers and plastics and conserve the environment. Therefore, it is of practical significance to develop convenient photochromic inks with a low cost and on a large scale. In this study, a simple one‐step hydrothermal route was used to prepare tungsten trioxide (WO₃) nanoparticles, which were further used to make photochromic inks and transparent photochromic films. The obtained transparent photochromic film could rapidly respond to UV light within tens of seconds, then return to its initial state, with different recovery times at different temperatures, and also exhibit good reversible coloration–bleaching effect. A typical polyethylene terephthalate (PET) foil coated with the photochromic ink could also be repeatedly printed with various patterns and displayed excellent rewritable performance over tens of cycles. This study proposes a simple method for widespread applications of WO₃‐based photochromic inks.     

Fourier Transform Infrared Spectroscopy Applied to the Characterisation of 17th–20th Century Calcographic and Xylographic Inks

 The aim of this paper is to optimize the analytical method for the characterisation of 17th–20th century calcographic and xylographic inks. It is very important to use not only non destructive techniques, but also analytical instruments that require a minimal amount of material so as to analyze unique or valuable samples, and simultaneously to obtain as much information as possible about their composition. This study compares different ways of sample preparation for further analysis by Fourier transform infrared spectroscopy. It has been possible to analyze the most important absorptions that appear in the spectra and therefore to associate them with the compounds contained in inks. Some of the compounds identified are: hydroxyapatite (calcium phosphate), Prussian blue (ferric ferrocyanide), linseed oil, carbonates, nitrates and sulfates. Received January 10, 1999. Revision March 17, 1999.     

In silico engineering of tailored ink-binding ability at molecular printboards.

Molecular recognition between guest ink molecules and beta-cyclodextrin (beta-CD) cavities at self-assembled monolayers provides a molecular printboard for nanopatterning applications. We recently used molecular dynamics (MD) simulations to describe the specificity of ink-printboard binding and here extend the simulations to include charged cyclodextrin hosts, necessary to broaden the chemistry of molecular printboards and bind charged inks such as the ferrocenium cation. Shifting to high pH, or alternatively grafting a charged sidearm onto beta-CD, created three distinct types of anionic beta-CD cavity and we used electronic structure calculations and MD simulations to measure host-guest charge transfer and binding strengths. We find that steric recognition of uncharged organic molecules is retained at the charged printboards, and that improved guest-host electrostatic contacts can strengthen binding of larger inks while penalising small inks, enhancing the level of discrimination. A prudent choice of complementary host-guest shape and charge states thus provides a means of tuning both ink binding strength and specificity at molecular printboards.     

Study of the copper effect in iron-gall inks after artificial ageing

Iron-gall inks consist of a mixture of vitriols (sulphates of certain metals), gall nut extracts and arabic gum. The association of the iron(II) sulphate present in vitriols, and the gallic acids present in the gall nut extracts induces, after exposure to oxygen, the formation of dark coloured compounds of ink. In addition to iron, this kind of inks contains other metals, such as copper, zinc, and nickel. Among them, copper could be considered the most important because, owing to its catalytic ability, it can be involved in the processes concerning formation and stability of iron complexes, which are responsible for the ink dark colour. For this purpose, four different iron-gall inks containing increasing amounts of copper sulphate were prepared according to a traditional receipt and applied on paper supports. The ink-stained paper specimens were subjected to an intense analytical program to investigate their chemical and physical modifications after artificial ageing (both temperature/humidity and ultraviolet light ageing). The role of copper in the iron-gall inks was evaluated using optical microscopy, colorimetric measurements, X-ray fluorescence (XRF), X-ray diffraction analysis (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX) and Fourier transform infrared spectroscopy (FTIR). For the evaluation of the oxidation state of iron and copper, X-ray absorption spectroscopy (XANES) was used. All results indicate that the presence of copper in iron-gall ink causes colour variation, affects the migratory behaviour of iron in the paper, increases the formation of secondary products particularly when ageing process based on temperature/humidity variations is considered.     

New Promises and Opportunities in 3D Printable Inks Based on Coordination Compounds for the Creation of Objects with Multiple Applications

This review focuses on the usefulness of coordination bonds to create 3D printable inks and shows how the union of chemistry and 3D technology contributes to new scientific advances, by allowing amorphous or polycrystalline solids to be transformed into objects with the desired shape for successful applications. The review clearly shows how there has been considerable increase in the manufacture of objects based on the combination of organic matrices and coordination compounds. These coordination compounds are usually homogeneously dispersed within the matrix, anchored onto a proper support or coating the printed object, without destroying their unique properties. Advances are so rapid that today it is already possible to 3D print objects made exclusively from coordination compounds without additives. The new printable inks are made mainly with nanoscale nonporous coordination polymers, metal–organic gels, or metal–organic frameworks. The highly dynamic coordination bond allows the creation of objects, which respond to stimuli, that can act as sensors and be used for drug delivery. In addition, the combination of metal–organic frameworks with 3D printing allows the adsorption or selective capacity of the object to be increased, relative to that of the original compound, which is useful in energy storage, gas separation, or water pollutant elimination. Furthermore, the presence of the metal ion can give them new properties, such as luminescence, that are useful for application in sensors or anticounterfeiting. Technological advances, the combination of various printing techniques, and the properties of coordination bonds lead to the creation of surprising, new, printable inks and objects with highly complex shapes that will close the gap between academia and industry for research into coordination compounds.     

Volatile compounds profiling by using proton transfer reaction‐time of flight‐mass spectrometry (PTR‐ToF‐MS). The case study of dark chocolates organoleptic differences

Direct‐injection mass spectrometry (DIMS) techniques have evolved into powerful methods to analyse volatile organic compounds (VOCs) without the need of chromatographic separation. Combined to chemometrics, they have been used in many domains to solve sample categorization issues based on volatilome determination. In this paper, different DIMS methods that have largely outperformed conventional electronic noses (e‐noses) in classification tasks are briefly reviewed, with an emphasis on food‐related applications. A particular attention is paid to proton transfer reaction mass spectrometry (PTR‐MS), and many results obtained using the powerful PTR‐time of flight‐MS (PTR‐ToF‐MS) instrument are reviewed. Data analysis and feature selection issues are also summarized and discussed. As a case study, a challenging problem of classification of dark chocolates that has been previously assessed by sensory evaluation in four distinct categories is presented. The VOC profiles of a set of 206 chocolate samples classified in the four sensory categories were analysed by PTR‐ToF‐MS. A supervised multivariate data analysis based on partial least squares regression‐discriminant analysis allowed the construction of a classification model that showed excellent prediction capability: 97% of a test set of 62 samples were correctly predicted in the sensory categories. Tentative identification of ions aided characterisation of chocolate classes. Variable selection using dedicated methods pinpointed some volatile compounds important for the discrimination of the chocolates. Among them, the CovSel method was used for the first time on PTR‐MS data resulting in a selection of 10 features that allowed a good prediction to be achieved. Finally, challenges and future needs in the field are discussed.     

Structural and magnetic resolution of a two-step full spin-crossover transition in a dinuclear iron(II) pyridyl-bridged compound

A dinuclear iron(II) complex containing the new pyridyl bridging ligand, 2,5-di(2',2'-dipyridylamino)pyridine (ddpp) has been synthesised and characterised by single-crystal X-ray diffraction, magnetic susceptibility and M?ssbauer spectral methods. This compound, [Fe(2)(ddpp)(2)(NCS)(4)]4 CH(2)Cl(2), undergoes a two-step full spin crossover. Structural analysis at each of the three plateau temperatures has revealed a dinuclear molecule with spin states HS-HS, HS-LS and LS-LS (HS: high spin, LS: low spin) for the two iron(II) centres. This is the first time that resolution of the metal centres in a HS-LS ordered state has been achieved in a two-step dinuclear iron(II) spin-crossover compound. Thermogravimetric data show that the dichloromethane solvate molecules can be removed in two distinct steps at 120 degrees C and 200 degrees C. The partially de-solvated clathrate, [Fe(2)(ddpp)(2)(NCS)(4)]CH(2)Cl(2), undergoes a one-step transition with an increased transition temperature with respect to the as synthesised material. Structural characterisation of this material reveals subtle changes to the coordination geometries at each of the iron(II) centres and striking changes to the local environment of the dinuclear complex. The fully de-solvated material remains high spin over all temperatures. Interestingly, the solvent can be re-introduced into the monosolvated solid to achieve complete conversion back to the original two-step crossover material, [Fe(2)(ddpp)(2)(NCS)(4)]4 CH(2)Cl(2).     

Depth-resolved speciation of nitrogen compounds in environmental solids

Dynamic SIMS has been applied to the analysis of inorganic and organic nitrogen compounds. A depth-resolved speciation of nitrogen, based on the intensities of small ionic clusters, has been developed. An evaluation method is outlined to distinguish inorganic and organic nitrogen compounds. Furthermore, several organic compound families can be recognised including detailed nitrogen speciation. Because this method is suitable even for characterisation of complex mixtures, urban outdoor aerosol particles have been analysed with Dynamic SIMS.     

Matrix-assisted polymer pen lithography induced Staudinger Ligation

The Staudinger Ligation has been combined with Polymer Pen Lithography to create patterns of fluorescent and redox-active inks with 1-micrometer scale feature diameters over centimeter-scale areas. This report presents a straightforward strategy to expand the scope of organic reactions employed in surface science.     

Synthesis, physicochemical properties and antioxidant activity of deferiprone-cyclodextrin conjugates and their iron(III) complexes

3-Hydroxy-1,2-dimethylpyridin-4(1H)-one (deferiprone) is a successful iron chelator, which has been widely investigated for its activity in mitigating iron overload and in protecting against oxidative stress due to Reactive Oxygen Species (ROS). Herein, we present the synthesis, characterisation, physicochemical properties and antioxidant activity of two novel bioconjugates of β-cyclodextrin bearing the deferiprone moiety either on the upper rim (1) or on the lower rim (2) of the cyclodextrin and their iron(III) complexes. Protonation and iron stability constants were measured by spectrophotometric titration for the two systems and antioxidant activity studied for both the ligands and the iron(III) complexes.     

Historical iron gall ink containing documents — Properties affecting their condition

Iron gall ink, also referred to as iron gallotannate ink, is one of the most important inks in the history of western civilisation, and was in widespread use from the middle ages until the 20th century. Unfortunately, iron ions and acids present in these inks induce enhanced degradation of paper, thus severely damaging numerous historical artefacts. Yet, when examining documents, it is frequently observed that not all materials containing iron gall ink are suffering from ink corrosion. While some are completely destroyed, others may be in excellent condition even centuries after their creation. In order to establish the main properties of materials, common to severely degraded documents, the effects of the type and quantity of metal ions in the ink, as determined by in-air PIXE method, pH of the ink on paper, grammage of paper, its absorptivity and the width of ink lines were evaluated against the extent of corrosion. Using multiple linear regression analysis, a correlation has been obtained between the width of the applied ink lines, pH, grammage of paper and the extent of ink corrosion. Based on these factors, which can be acquired non-destructively from most historical documents, it is therefore possible to predict the stability of historical iron gall ink containing paper.     

A study of ochres from an Australian aboriginal bark painting using thermal methods

The potential of thermogravimetric analysis (TG) as a tool for the characterisation of ochre paint used in indigenous Australian bark paintings has been investigated. TG has been combined with differential scanning calorimetry (DSC) and mass spectrometry (MS) to identify and quantify the main inorganic and organic components present in the paints. The results obtained were supported by comparison with infrared spectra and XRD data obtained for the same specimens. The potential of thermal methods for the characterisation ochres has been demonstrated, with subtle differences between small samples being able to be identified.