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A series of medium- and long-chain zinc carboxylates was analyzed by ultra-high-field 67Zn NMR, 13C NMR and FTIR spectroscopy. Novel crystal structures for three of these carboxylates are also reported.

Advanced materials 35(16), 2210052 (2023). doi:10.1002/adma.202210052, Published by Wiley-VCH, Weinheim

The Thannhauser Collection of the Solomon R. Guggenheim Museum, New York, represents an important survey of European avant-garde art production during the late 19th and early 20th centuries. Among the works included in this collection are three paintings by Vincent van Gogh, namely Roadway with Underpass (1887), Landscape with Snow (1888), and Mountains at Saint-Rémy (1889). These examples each exhibit some degree of surface alteration, including fading of specific pigments and, in one case, a non-original, discolored varnish, resulting in obscured color and spatial relationships, as well as being the subject of questions regarding authenticity in the case of the two earlier pictures. Initial examination involved documentation of the brushwork, paint quality, and distribution of colors under magnification. Infrared (IR) and ultraviolet (UV) photography, as well as X-radiography, provided additional information on the surface coatings, the structure of the works, and their supports. Subsequently, an in-depth scientific investigation of the ground and paint layers, with a special focus on fading colors and altered surfaces, was carried out non-invasively with point and macro-X-ray fluorescence (XRF) spectroscopy, visible reflection spectroscopy, and multi-channel visible spectrum four-light imaging, followed by the analysis of cross sections and dispersed pigment samples by means of optical microscopy, transmission Fourier-transform infrared (FTIR) and Raman spectroscopies, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), as well as high-performance liquid chromatography with photodiode array detection (HPLC-PDA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Results indicated that both the brushwork and artist's palette of all three paintings are consistent with data previously reported for other Van Gogh works and with pigments described in the artist’s letters to his friends and his brother Theo. Most notably, evidence of biodeterioration and paint alteration phenomena was found on Roadway with Underpass, while specific pigments such as eosin red—historically sold as geranium lake—were detected in areas of Landscape with Snow and Mountains at Saint-Rémy that display severe fading. In addition to assisting the development of a suitable plan for the conservation of the 1887 painting, this study traces the progression of Van Gogh’s practice over three years critical to his artistic development, discusses the historical context in which each masterpiece was created, identifies the range of materials and techniques used, and addresses authenticity questions by providing a comparison with results of scientific analysis from other similar works.

Nuclear magnetic resonance spectroscopy has advanced our understanding of cultural heritage objects. Solution NMR, solid state NMR, unilateral NMR, magnetic resonance imaging (MRI) and other MR techniques have been used on a wide variety of materials such as stone, ceramics, paintings, biological remains, paper, wood, textiles, resins, gums, and synthetic materials. This review highlights NMR studies that provide structural and chemical identification, moisture content and distribution, uncovers artistic techniques, determines geographical origins, identifies constituent materials of an object and helps to determine the best cleaning or treatment method for conservation. In addition, physical and chemical transformations and structural modifications due to deterioration of an object can be monitored by NMR methods, and this information provides conservators with clues as to the most appropriate methods of preservation of a unique artifact. With the continued development of NMR pulse sequences, probes and sensors, the sensitivity and utility of NMR spectroscopy in cultural heritage continues to grow.

Seven salted paper prints from the 1840s and 1850s in the permanent collection of The Metropolitan Museum of Art were included in the exhibition, Paradise of Exiles: Early Photography in Italy, fro...

Plasmons, the collective oscillations of mobile electrons in metallic nanostructures, interact strongly with light and produce vivid colors, thus offering a new route to develop color printing technologies with improved durability and material simplicity compared with conventional pigments. Over the last decades, researchers in plasmonics have been devoted to manipulating the characteristics of metallic nanostructures to achieve unique and controlled optical effects. However, before plasmonic nanostructures became a science, they were an art. The invention of the daguerreotype was publicly announced in 1839 and is recognized as the earliest photographic technology that successfully captured an image from a camera, with resolution and clarity that remain impressive even by today’s standards. Here, using a unique combination of daguerreotype artistry and expertise, experimental nanoscale surface analysis, and electromagnetic simulations, we perform a comprehensive analysis of the plasmonic properties of these early photographs, which can be recognized as an example of plasmonic color printing. Despite the large variability in size, morphology, and material composition of the nanostructures on the surface of a daguerreotype, we are able to identify and characterize the general mechanisms that give rise to the optical response of daguerreotypes. Therefore, our results provide valuable knowledge to develop preservation protocols and color printing technologies inspired by past ones.

As a key participant in the 1686 revitalization of the Guild of Painters and Gilders of Mexico City, Cristobal de Villalpando (c. 1649–1714) played a critical role in establishing a high standard of practice for painters in seventeenth-century Mexico and beyond.[1][1] Signed and dated at the

The spectroscopic study of pigments and binders in works of art is described, focusing not only on the characterization of artists' materials, but also the presence of degradation. Several examples have been selected to cover the most important issues that a young chemist with some knowledge of conservation practices must take into account in the development of their career. The chapter is written in such a way that the most important issues of the analytical research around a project of diagnostics prior to conservation/restoration restoration works are described at the level of master's studies.

Chemistry - a European journal 27(64), 15889-15897 (2021). doi:10.1002/chem.202102938, Published by Wiley-VCH, Weinheim

The quantitative evaluation of the three-dimensional (3D) morphology of porous composite materials is important for understanding mass transport phenomena, which further impact their functionalities and durability. Reactive porous paint materials are composites in nature and widely used in arts and technological applications. In artistic oil paintings, ambient moisture and water and organic solvents used in conservation treatments are known to trigger multiple physical and chemical degradation processes; however, there is no complete physical model that can quantitatively describe their transport in the paint films. In the present study, model oil paints with lead white (2PbCO3·Pb(OH)2) and zinc white (ZnO) pigments, which are frequently found in artistic oil paintings and are associated with the widespread heavy metal soap deterioration, were studied using synchrotron X-ray nano-tomography and unilateral nuclear magnetic resonance. This study aims to establish a relationship among the paints’ compositions, the 3D morphological properties and degradation. This connection is crucial for establishing reliable models that can predict transport properties of solvents used in conservation treatments and of species involved in deterioration reactions, such as soap formation.

Three Japanese woodblock prints from the Edo period (1603–1868) underwent a scientific investigation with the aim of understanding the changes in the colorants used in Japanese printing techniques. A multi-analytical approach was adopted, combining non-invasive techniques, such as fiber optic reflectance spectroscopy (FORS), Raman spectroscopy, multispectral imaging (MSI), and macro X-ray fluorescence (MA-XRF) with minimally invasive surface-enhanced Raman spectroscopy (SERS). The results enabled many of the pigments to be identified and their distribution to be studied, apart from two shades of purple of organic composition. Consequently, the potential of high-pressure liquid chromatography tandem mass spectrometry (HPLC–MS/MS) was explored for the first time with application to Japanese woodblock prints. The intrinsic sensitivity of the instrument and an effective extraction protocol allowed us to identify a mixture of dayflower (Commelina communis) blue and safflower (Carthamus tinctorius) red in purple samples constituted of 2–3 single fibers. In addition to the innovative integration of MA-XRF and HPLC–MS/MS to investigate these delicate artworks, the study concluded on the use of traditional sources of colors alongside newly introduced pigments in late Edo-period Japan. This information is extremely important for understanding the printing practices, as well as for making decisions about display, conservation, and preservation of such artworks.

Among the thirty-six paintings ascribed to the Dutch seventeenth century artist Johannes Vermeer (1632–1675), Mistress and Maid, in The Frick Collection, stands out for the large-scale figures set against a rather plain background depicting a barely discernible curtain. Although generally accepted as among the late works of the artist and dated to 1667–1668, for decades scholars have continued to puzzle over aspects of this portrayal. When the painting was cleaned and restored in 1952, attempts to understand the seeming lack of finish and simplified composition were hampered by the limited technical means available at that time. In 1968, Hermann Kühn included Mistress and Maid in his groundbreaking technical investigation ‘A Study of the Pigments and the Grounds Used by Jan Vermeer.’ In the present study, imaging by infrared reflectography and macro-X-ray fluorescence (MA-XRF) revealed significant compositional changes and drew focus to areas of suspected color change. Three of the samples taken by Hermann Kühn, and now in the archive of the Doerner Institut in Munich, were re-analyzed, along with a few paint samples taken from areas not examined in the 1968 study, using scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS) and Raman spectroscopy. These analyses made it possible to further visualize detailed compositional elements in the background of the painting that were later painted out, and to characterize darkening and color changes in different paint passages.

Heavy metal carboxylate or soap formation is a widespread deterioration problem affecting oil paintings and other works of art bearing oil-based media. Lead soaps are prevalent in traditional oil paintings because lead white was the white pigment most frequently chosen by old masters for the paints and in some cases for the ground preparations, until the development of other white pigments from approximately the middle of the 18th century on, and because of the wide use of lead-tin yellow. In the latter part of the 19th century, lead white began to be replaced by zinc white. The factors that influence soap formation have been the focus of intense study starting in the late 1990s. Since 2014, nuclear magnetic resonance (NMR) studies have contributed a unique perspective on the issue by providing chemical, structural, and dynamic information about the species involved in the process, as well as the effects of environmental conditions such as relative humidity and temperature on the kinetics of the reaction(s). In this review, we explore recent insights into soap formation gained through solid-state NMR and single-sided NMR techniques.

Banana starch was modified with B bis(2-hydroxyethyl) terephthalate and its instrumental characterization allowed to propose a chemical structure. In the carbon 6 (C6) of the starch the modification reactionwas carried out. The morphology of starch changes due to its chemical modification. The modified starch showed a lower crystallinity and thermal stability, compared to the native starch favoring its film formation. The electrical conductivity of the modified starch films was 2.7 times higher than that for the native starch film. The aqueous hydrolysis of the modified starch films was carried out obtaining a degradation of 77% in a determined time. Modified starch films present different mechanical properties compared to native starch film. These results have high application potential to be used in PET degradation products., We are grateful to Concejo Nacional de Ciencia yTecnología (Conacyt), Instituto de Ciencia y Tecnología de Polímeros(ICTP), Universidad del Papaloapan campus Tuxtepec, MartínezOlguiín Aldo de Jesús, Martha Ferrer Guadalupe and Martha RocioValencia Estacio for their assistance on this article.

Many oil paintings, dating from the 15th century to the present, are affected by the formation of heavy-metal carboxylates (soaps) that alter the structural integrity and appearance of the works. Through transport phenomena not yet understood, free fatty acids formed from oils used as binders migrate through the paint film and react with heavy-metal ions that are constituents of pigments and/or driers, forming metal carboxylates. The local molecular dynamics of fatty acids and metal carboxylates are factors influencing material transport in these systems. We report temperature-dependent 2H NMR spectra of palmitic acid and lead palmitate as pure materials, in cross-linked linseed oil films, and in a lead white linseed oil paint film as part of our broader research into metal soap formation. Local dynamics at the α carbon, at the terminal methyl group, and at the middle of the fatty acid chain were observed in specifically deuterated materials. Changes in the dynamic behavior with temperature were observed by the appearance of two species, a solid-like material and a liquid-like material. The relative amounts of the two phases and their deuterium NMR parameters indicate that the amount of liquid-like material and the local dynamics at that site increase with temperature. At the three locations along the chain and at all temperatures, there is a larger percentage of acyl chains of both palmitic acid and lead palmitate that are "mobile" or liquid-like in linseed oil films than there are in the pure materials. However, the percentage of liquid-like species is decreased in a lead white paint film, as compared to a linseed oil matrix. In addition, these experiments indicate that there is a larger percentage of liquid-like acyl chains of palmitic acid than of lead palmitate under identical conditions in these model paint systems.

Among the holdings of the Solomon R. Guggenheim Foundation, New York, is a large-scale portrait by Édouard Manet that remained apparently unfinished upon the artist’s death, in April 1883. This work, now known as Woman in Striped Dress, belongs to Manet’s late artistic production and dates from around 1877 to 1880. A collaborative endeavor entailing archival research and scientific analysis revealed that the composition had suffered dramatic alterations prior to its arrival at the museum in 1965 as an extended loan, likely carried out to “finish” the picture in order that it would be marketable and to increase its sale value. Among the main changes explored in this technical study are the reductions in the canvas size and subsequent varnishing campaigns. Furthermore, along with a detailed characterization of the original materials present in the ground and paint layers, this research contributed to the identification of posthumous retouchings, possibly executed concurrently with trimming the canvas along both sides and at the top edge. The investigation was instrumental in devising an appropriate treatment to remove the discolored varnish and select areas of retouching, which obscured significant details of the composition and Manet’s delicate brushwork.

Vincent van Gogh’s still lifes Irises and Roses were investigated to shed light onto the degree to which the paintings had changed, both individually and in relation to each other since they were painted, particularly in regard to the fading of the red lakes. Non-invasive techniques, including macroscopic X-ray fluorescence mapping, reflectance imaging spectroscopy, and X-radiography, were combined with microanalytical techniques in a select number of samples. The in-depth microchemical analysis was necessary to overcome the complications that arise when evaluating by non-invasive methods alone the compositions of passages with complex layering and mixing of paints. The results obtained by these two approaches were complemented by color measurements performed on paint cross-sections and on protected edges, and with historical information provided by the artist’s own descriptions, early reviews and reproductions, and the data was used to carry out digital color simulations that provided, to a certain extent, a visualization of how the paintings may have originally appeared. Graphical abstract Irises, 1890, Vincent van Gogh. The Metropolitan Museum of Art #58.187. Zn (upper right), Pb (bottom left), and Br (bottom right) distribution maps acquired by XRF imaging.

In this work, we present a complete Raman investigation of a class of compounds that has not received great attention yet, the red naphthol-based azo dyes. We selected a group of red azo dyes often used by artists in inks and lake pigments: acid red 1, acid red 14, acid red 18, acid red 26, acid red 27, and acid red 73. A set of reference materials was studied by dispersive Raman, FT-Raman, and surface-enhanced Raman spectroscopy. The reference spectra were used in the study of late 19th century Japanese polychrome woodblock prints. The azo dyes selected for this study generally gave good Raman spectra at all excitation wavelengths. The results obtained by the various Raman techniques are compared, and the main difficulties in the identification of the compounds in works of art are illustrated and discussed. The fluorescence coming from the matrix in which the colorants are embedded can obscure their Raman signal. For this reason, the advantages and drawbacks of surface-enhanced Raman spectroscopy with non-sampling extraction of the colorants have been evaluated. Copyright © 2017 John Wiley & Sons, Ltd.

This essay takes Pollock’s painting Pasiphae as a comparative for Mural. Both paintings were begun in 1943 and were significantly larger in scale than the artist’s previous works. Using tec...

Dynamic nuclear polarization (DNP) is used to enhance the (ultra)wideline 207Pb solid-state NMR spectra of lead compounds of relevance in the preservation of cultural heritage objects. The DNP SSNMR experiments enabled, for the first time, the detection of the basic lead carbonate phase of the lead white pigment by 207Pb SSNMR spectroscopy. Variable-temperature experiments revealed that the short T'2 relaxation time of the basic lead carbonate phase hinders the acquisition of the NMR signal at room temperature. We additionally observe that the DNP enhancement is twice as large for lead palmitate (a lead soap, which is a degradation product implicated in the visible deterioration of lead-based oil paintings), than it is for the basic lead carbonate. This enhancement has allowed us to detect the formation of a lead soap in an aged paint film by 207Pb SSNMR spectroscopy; which may aid in the detection of deterioration products in smaller samples removed from works of art.

Heavy metal carboxylate degradation severely affects thousands of oil paintings. Relative humidity has been reported to accelerate the rate of the reactions. To evaluate its role further, water diffusion and molecular mobility of protons in linseed oil-based lead white paints were studied by unilateral NMR and

Heavy metal carboxylate degradation severely affects thousands of oil paintings. Relative humidity has been reported to accelerate the rate of the reactions. To evaluate its role further, water diffusion and molecular mobility of protons in linseed oil-based lead white paints were studied by unilateral NMR and 1H HRMAS spectroscopy. The results indicate that exposure to high %RH for relatively long times affects the dynamics of the oil paint's mobile fraction and that the effect is more pronounced as the thickness of the film increases. It was found that the paint can absorb appreciable amounts of water and has a porosity of approximately 6 % available for the diffusion of water, for which a regime of restricted diffusion was observed. Furthermore, the presence of bound and free-moving water, due to the possible formation of hydrated ionic-group clusters, supports the hypothesis of a polymeric/ionomeric network, as well as regions of essentially water free to move as in the bulk. The findings allow a better understanding of the role of water as a factor activating the degradation process in linseed oil-based lead white paints.

El presente trabajo consiste en desarrollar un Plan Estratégico para la empresa en el período 2018-2022, donde se plasmen todos los lineamientos necesarios para que Comunal Coworking sea una empresa con una proyección de crecimiento sostenido en el tiempo. Este plan contendrá los capítulos mencionados a continuación. Comunal Coworking es una empresa peruana pionera en el rubro del coworking, ofrece desde el año 2013 oficinas completamente equipadas en los distritos de Barranco, Miraflores y San Isidro. La empresa, con el afán de fortalecerse y crecer en el tiempo, ha establecido una marca sólida y reconocida en este nuevo sector; por lo que se vio en la necesidad de contar con lineamientos estratégicos que la sostengan en el tiempo. Para lo cual se ha elaborado un plan estratégico para los periodos comprendidos entre los años 2018-2022. En la actualidad, existen factores externos dentro de la región que favorecen al país y al desarrollo de la empresa, como es la estabilidad del PBI e inflación y la tendencia al crecimiento económico en un ambiente político-democrático. Este plan propone una estrategia de penetración y desarrollo de producto, a través de la implementación de 50 iniciativas, que permitan minimizar los principales inconvenientes encontrados en la empresa y los conviertan en oportunidades, como son la falta de procesos y las funciones establecidas en la empresa, que no permiten estandarizar, administrar y mejorar la calidad de los servicios que se ofrecen. Trabajo de Investigación

To understand the mechanisms and factors that trigger soap formation and the dynamics of the reactive compounds in paints, advanced nuclear magnetic resonance (NMR) and X-ray analyses, complemented by analysis with FTIR spectroscopy, were performed on a series of lead carboxylates and model paint samples. Similar spectroscopy and lead coordination were observed for lead carboxylates of carbon chain length of 9 to 11 and 16 (palmitic acid) and 18 (stearic acid). Experiments as a function of temperature and humidity provided insight into the factors that increase soap formation. The local dynamics of palmitic acid and lead palmitate, in a linseed oil matrix at different temperatures (T) were measured by 2H NMR spectroscopy. The results show the extent of mobility of palmitic acid and lead palmitate in the paint matrix, how they differ, and how they depend on T. The kinetics of soap formation in model paint films subjected to different relative humidities was monitored by 13C NMR spectroscopy; the rate of soap formation increases with relative humidity. The results are discussed in the context of their implications for the conservation and preservation of works of art affected by lead soap formation.

A basic recipe for making a Cr logwood ink dating to 1847 was adapted in order to obtain hues varying from orange to dark brown. The inks synthesized were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy, liquid chromatography–diode array detection–quadrupole time-of-flight–mass spectrometry, and liquid chromatography–inductively coupled plasma–mass spectrometry to gain insight into the spectroscopic properties of the compounds responsible for the inks colors and to obtain Raman spectra that can be used for their non-invasive identification in works of art and in historic documents. It was observed that hematein and logwood oxidation products are present in the inks and that their relative proportions determine the inks hues. It was also found that relatively small variations in the basic recipe, such as in the temperature that the logwood and K2CrO4 mixture were heated at, gave inks with different hues. The Raman spectra acquired in the laboratory samples were used to characterize the ink used by Vincent van Gogh in Street in Saintes-Maries-de-la-Mer. Copyright © 2016 John Wiley & Sons, Ltd.