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Abstract Indian yellow has always been a mysterious pigment. In 1883, an eye-witness account of its production described it as a urinary sediment from cows fed a mango leaves rich diet; this same account describes a set of manufacturing materials and samples sent to the Royal Botanic Gardens, Kew (England). Most of these original materials were recovered in 2016 from the Economic Botany Collection at Kew, and analyzed alongside known reference materials, to characterize the pigment materials, and to search for evidence of an animal origin. Component characterization and identification was performed using py (TMAH)-GC-MS, LC-MS, FTIR, Raman Spectroscopy, SEM-EDS, UVA-induced visible fluorescence, and polarized light microscopy. All the materials were shown to contain variable ratios of reported components of Indian yellow (euxanthic acid, euxanthone, and a sulfo-derivative of euxanthone), and some presented hippuric acid, a ruminant metabolite found in urine. This is the first substantial link between animal urine and the pigment Indian yellow. When possible, the interior and exterior of the pigment-balls were characterized, and a higher amount of euxanthone was consistently detected on the exposed exterior of the ball. It is proposed, that euxanthone may be a chemical marker for the degradation of Indian yellow. A laboratory prepared euxanthone was used for comparison; this paper presents the characterization data for euxanthone, much of which is the first time it has been reported in the literature. Highlights • Discovery, sampling, and analysis of the historic samples and artifacts from the production of Indian yellow pigment. • First discovery of a chemical marker of mammalian urine– hippuric acid – in Indian yellow pigment. • First published Raman spectrum of euxanthone. [ABSTRACT FROM AUTHOR]

BaAl 2-x Mn x O 4+y (0 ≤ x ≤ 0.10) showing intense turquoise to green colors were prepared by the sol-gel method from metal nitrides as precursors and followed by a thermal treatment at 900 °C. The X-ray diffraction of all of the as-synthesized samples are indexed with BaAl 2 O 4 stuffed tridymite structure. The oxidation state of Mn is confirmed to be +5 by X-ray photoelectron spectroscopy analysis. The colors of the samples are tuned to intense turquoise and green with the increase of Mn content. The optical properties are characterized by UV–Vis absorbance spectra and CIE L ∗ a ∗ b ∗ coordinates. The reason for the intense colors is due to the Mn 5+ doping in the [AlO 4 ] tetrahedral sites. The pigments are applied to poly(methyl methacrylate) (PMMA) and the colours of the polymer composite were characterized. [ABSTRACT FROM AUTHOR]

A high triplet energy core structure, carbazole-dibenzothiophene, was designed and synthesized as a building block of high triplet energy host materials for blue phosphorescent organic light-emitting diodes. The carbazole and dibenzothiophene were interconnected via 3- position of carbazole and 2- position of dibenzothiophene not to sacrifice the high triplet energy the two units. Three compounds with phenyl, dibenzothiophene and 9-phenylcarbazole functional groups as side groups of the carbazole-dibenzothiophene main structure worked as hosts providing high triplet energy over 2.80 eV and the host with a dibenzothiophene substituent achieved high external quantum efficiency over 20% in blue phosphorescent organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2 ) is an oxidative stress marker in various disease. The local concentration of H 2 O 2 is related to cancer, a reliable and simple assay detecting H 2 O 2 level in cells is therefore critical. Here, we have developed a fluorescence probe PEP-Npb1-Cy3 which can be used to detect H 2 O 2 in living ovarian cancer cells. The probe is developed based on employing the oxide reactivity of 1, 8-naphthalimide boric acid towards H 2 O 2 , which yields a turn-on fluorescence signal and exhibits high selectivity and sensitivity. Our collective results support the applicability of PEP-Npb1-Cy3 as a powerful tool for imaging both exogenous and endogenous H 2 O 2 -involving biological events in ovarian cancer cells, which may have further biomedical applications. [ABSTRACT FROM AUTHOR]

Templated synthesis of CH 3 NH 3 PbBr 3 perovskite nanocrystals is facile, high-yield, ligand-free, and is another effective method aside from the colloidal method. However, the quantum yield (QY) is still inferior to that of the colloidal synthesized ones. In this report, we show that CH 3 NH 3 PbBr 3 nanocrystal within mesoporous silica with QY of 75% and full width at half-maximum (FWHM) of 22 nm are obtained through manipulating the molar ratio of CH 3 NH 3 Br versus PbBr 2 in precursor solution. It is found that excess CH 3 NH 3 Br can passivate the surface trap states, reduce nanocrystal size and narrow down the size distribution effectively. These features contribute to the rising of QY, blue-shifting of emission maximum and narrowing down of FWHM. The influence of excess CH 3 NH 3 Br can be interpreted in terms of enrichment on the interface of solvent/air because of amphipathy. Moreover, these CH 3 NH 3 PbBr 3 - mesoporous silica composites present good stability. They preserve 90% of its initial QY after a storage in wet weather with relative humidity of 70 ± 5% for 3 months. The synthesis method proposed in this research provides an effective way to achieve perovskite nanocrystals within mesoporous silica with high efficiency and stability. [ABSTRACT FROM AUTHOR]

Colloidally synthesized semiconductor nanoparticles have been receiving much attention due to their potential application in the area of photovoltaics, optic devices, biology, and medicine. This work explains how semiconductor CdTeSe/ZnS quantum dots (QDs) with the surface modified by trioctylphosphine oxide (TOPO) were dispersed on the surface of water. The studies of the organization and behavior of formation layers of CdTeSe/ZnS were followed by surface pressure-area isotherm measurements, in-situ absorption spectroscopy, Brewster Angle Microscopy (BAM) and surface potential measurements. The conducted research shows that CdTeSe/ZnS QDs form a tightly-packed, thin layer at the water-air interface, which can be easily deposited on different surfaces with the Langmuir-Blodgett and Langmuir-Schafer techniques. [ABSTRACT FROM AUTHOR]

This study describes the synthesis and characterization of a series of regioregular dithieno(3,2-b;2′,3′- d )-silole (DTSi)- and dithieno(3,2-b;2′,3′- d )-germole (DTGe)-based small molecules—7,7′-(4,4-bis(2-ethylhexyl)-4 H -silolo[3,2- b :4,5- b ′]dithiophene-2,6-diyl)bis(5-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5-yl)benzo[ c ][1,2,5]thiadiazole) (DTSi(BTFTh 2 ) 2 ), 7,7′-(4,4-bis(2-ethylhexyl)-4 H -germolo[3,2- b :4,5- b ′]dithiophene-2,6-diyl)bis(5-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5-yl)benzo[ c ][1,2,5]thiadiazole) (DTGe(BTFTh 2 ) 2 ), 7,7′-(4,4-bis(2-ethylhexyl)-4 H -silolo[3,2- b :4,5- b ′]dithiophene-2,6-diyl)bi-s(4-(benzofuran-2-yl)-5-fluorobenzo[ c ][1,2,5]thiadiazole) (DTSi(BTFBFu) 2 ), and 7,7′-(4,4-bis(2-ethylhexyl)-4 H -germolo[3,2- b :4,5- b ′]dithiophene-2,6-diyl)bis(4-(benzofuran-2-yl)-5-fluorobenzo[ c ][1,2,5]thiadiazole) (DTGe(BTFBFu) 2 ) (DTSi(BTFTh 2 ) 2 , DTGe(BTFTh 2 ) 2 , DTSi(BTFBFu) 2 , and DTGe(BTFBFu) 2 in which two F atoms are in a symmetric distal/distal configuration relative to the central core units. The optical and electrochemical properties are strongly influenced owing to changes of the terminal units (BFu and Th 2 ) rather than by the tuning of the core units (DTSi and DTGe). In addition to a high fraction of the edge-on orientation in the neat films of all of the molecules, the presence of hexyl side chains in the Th 2 terminal units are found to play a critical role in forming high-quality films, leading to homogeneous and smooth surfaces in the films of Th 2 -containing molecules. When used as donor materials in small-molecule:fullerene solar cells, the best power-conversion efficiency of 3.26% was achieved with the DTSi(BTFTh 2 ) 2 -based system. Our study herein provides a relevant step toward understanding such isomorphic small molecules. [ABSTRACT FROM AUTHOR]

In this work we report on the synthesis of a pyridyl/phenolic/benzothiazole functionalized colorimetric receptor ( BPAP ) that can selectively recognise Fe(III) and Fe(II) ions in aqueous medium with visible, naked eye colour changes. Moreover, BPAP behaves as a ‘turn-on’ fluorescent chemosensor, showing an excellent sensitivity towards Zn 2+ and Cd 2+ cations in water by exhibiting fluorometric change. BPAP exhibited a visible detection limit of 5.5 μM and 2.5 μM for Fe 3+ and Fe 2+ , respectively, and a fluorometric selectivity towards Zn 2+ and Cd 2+ ions with lower detection limits of 205 nM and 642 nM. To understand the mode of binding to the sensor, both the nude sensor and the Zn-complex were isolated and characterized by X-ray crystallography. In Zn-BPAP , the ligand acts as neutral tridentate through N pyridine , N amine and N amide donor atoms. The N atom of benzothiazole group and the OH group of the phenole unit are not coordinated. Computational DFT study was performed on the free ligand BPAP and complex with Zn 2+ to investigate the interaction site, to calculate the energies of the frontier molecular orbitals and to corroborate some of the experimental results. [ABSTRACT FROM AUTHOR]

Solvent effects on the absorption and emission spectra of organic compounds have been widely observed. It is usually found that the positions, intensities and shapes of its bands are usually modified by these solvents. The solvent effects on intramolecular charge transfer (ICT) process have been extensively reported, whereas the solvent effect on photoinduced electron transfer (PET) process is scarce. In this contribution, it was disclosed that boronic acid derived salicylidenehydrazone complexes (BSs), BS-DPE and BS-DPBDE, with two perpendicular ICT states developed a non-fluorescent PET compounds through separating its two ICT states by boron node. Relative strong acidic proton in non-hydrogen-bond accepting solvent were proved to actuate the vanishment of PET and reinstatement of its fluorescence. [ABSTRACT FROM AUTHOR]

In this article, we acquire a novel Na 2 BiMg 2 (VO 4 ) 3 phase (abbreviated as NBMVO) via the substitution of Ca 2+ by Na + and Bi 3+ ions in Ca 2 NaMg 2 (VO 4 ) 3 . A series of Eu 3+ /Sm 3+ -doped Na 2 BiMg 2 (VO 4 ) 3 phosphors were synthesized via a high-temperature solid-state reaction route. XRD patterns for the prepared samples can be assigned to the standard Ca 2 NaMg 2 (VO 4 ) 3 phase. For the Na 2 BiMg 2 (VO 4 ) 3 host, the emission spectrum shows a wide band from 400 to 800 nm peaking at 535 nm under the optimal 378 nm excitation, which can be deconvoluted into two symmetric bands around 521 and 579 nm corresponding to transitions 3 T 2 → 1 A 1 and 3 T 1 → 1 A 1 from the (VO 4 ) 3- group, respectively. Monitored at 535 nm, the excitation spectrum exhibits a broad band with two peaks at 378 nm (26455 cm −1 ) and 324 nm (30864 cm −1 ), which originate from the transitions 1 T 2 ← 1 A 1 and 1 T 1 ← 1 A 1 of the (VO 4 ) 3- tetrahedron, respectively. When Eu 3+ or Sm 3+ is doped into the host, the emission spectra display both the host and the Eu 3+ or Sm 3+ characteristic emission peaks upon 378 nm excitation, moreover, the excitation spectra monitored at the Eu 3+ (607.5 nm) or Sm 3+ (650 nm) characteristic peaks contain both the host excitation band as well as the Eu 3+ or Sm 3+ characteristic excitation peaks. These results demonstrate an efficient energy transfer from the host to the Eu 3+ or Sm 3+ ions. Furthermore, the variation of the emission spectra for samples doped with different Eu 3+ or Sm 3+ contents under 378 nm excitation (witnessed by a color change from yellowish green to orange/light orange upon 365 nm UV lamp excitation) and the corresponding decay times are further used to validate the energy transfer from the (VO 4 ) 3- group to the doped ions. The energy transfer mechanisms for NBMVO:Eu 3+ and NBMVO:Sm 3+ are determined to be electric dipole-quadrupole and dipole-dipole interactions, respectively. These results suggest that these materials have potential as candidate phosphors in UV/n-UV w-LED applications. [ABSTRACT FROM AUTHOR]

SBA-15 mesoporous materials loaded with 8%–42% TiO 2 were prepared by post-synthesis hydrolysis using ilmenite as the TiO 2 source. X-ray diffraction, high-resolution transmission electron microscopy, nitrogen adsorption–desorption measurements, and Fourier-transform infrared, X-ray photoelectron, Raman, and ultraviolet-visible spectroscopies were used to investigate the TiO 2 /SBA-15 morphology and crystal structure. The results show that TiO 2 was successfully loaded on the mesoporous SBA-15 and the highly ordered two-dimensional hexagonal structure was stable. The photocatalytic performances of the samples in dimethoate degradation under simulated solar light were investigated. The photocatalytic activity initially increased and then decreased with increasing TiO 2 loading. The 26% TiO 2 /SBA-15 sample showed the highest photocatalytic activity and completely degraded dimethoate within 7 h. The catalytic activity of TiO 2 /SBA-15 was 62% higher than that of pure TiO 2 . This may be because of a synergistic effect resulting from the adsorption of dimethoate on the mesoporous material. The presence of Ti–O–Si species enhances the TiO 2 surface acidity and formation of surface adsorption sites; The adsorption and electron delocalization properties of SBA-15 are the main reasons for the observed enhancement of the pesticide degradation rate. These improves the TiO 2 /SBA-15 photocatalytic activity. TiO 2 /SBA-15 maintained high photocatalytic activity and good stability during four cycles, with a dimethoate degradation rate greater than 94%. The byproducts generated during photocatalysis were identified using gas chromatography-mass spectrometry. The photocatalytic degradation of dimethoate followed first-order kinetics. The mechanism of the photocatalytic degradation of dimethoate was investigated. [ABSTRACT FROM AUTHOR]

The paper explores the perspective of using an urea and glycine fuel mixture in order to obtain brown, heat reflective iron-doped lanthanum aluminate LaAl 1-x Fe x O 3 (x = 0, 0.25, 0.5, 0.75) pigments, directly from the combustion reaction. The exothermic redox reactions were characterized by high combustion temperatures, ranging between 1712 °C (x = 0) and 1017 °C (x = 0.75), which facilitated the formation of perovskite solid solutions within a very short period of time, no further annealing needed. The crystallite size, specific surface area, colour and total solar reflectance of the pigments depend on the substitution degree of Al 3+ by Fe 3+ . The increase of Fe 3+ content resulted in lower combustion temperature, shorter reaction time and increased gases release rate, which are reflected in the linear decrease of crystallite size from 57 nm (x = 0) to 22 nm (x = 0.75), as well as the linear increase of specific surface area from 3.0 (x = 0) to 15.6 m 2 /g (x = 0.75). The brown hue was enhanced by the increase of the chromophore content. The total solar reflectance of the pigments decreased from 87.5% to 42.7% as the Fe 3+ content, x, increased from 0 to 0.75. At the same time, the total solar reflectance values of the coatings prepared using the obtained pigments decreased from 85.3% to 35.8% as the Fe 3+ content, x, increased from 0 to 0.75. [ABSTRACT FROM AUTHOR]

It has been known for many years that dyes and pigments are subject to light-induced degradation, or photodegradation, when exposed to light. It is the very reason why some beverages or medicines are wrapped in light-tight packaging materials, and why museums cover their windows with UV-blocking filters. The exact chemistry of light-induced degradation can be quite complex. Why and how are these dyes and colorants affected by light? How fast do these processes occur? Are there ways to prevent this from happening in a straight-forward and durable way? These were and still are questions that are relevant to the many fields where colorants are applied. In order to support these questions, we have tried to provide a broad overview of the research that has already been conducted on photodegradation of dyes and pigments and the analysis of photodegradation products. In those papers, the most important parameters that were discussed are the influence of the irradiation source, intensity and time, the presence or absence of oxygen, temperature, the effects that catalysts have, as well as the dye or pigment concentration. Additionally, we have investigated the differences found for photodegradation in solution and on substrates and specific parameters that may affect the processes in these media. • An increase in the light dose leads to increased photodegradation. • The effect of the wavelength is associated with the structure of the dye/pigment. • The presence of oxygen influences the photodegradation rate and mechanism. • Temperature influences photodegradation less compared to other parameters. • Photodegradation mechanisms in-solution may differ from those on substrates. [ABSTRACT FROM AUTHOR]

Materials in the full miscibility range of YInO 3 – YMnO 3 were prepared and compared to CI Pigment Blue 28 (CoAl 2 O 4 spinel) industrial pigments. The materials were analyzed by XRD, UV–Vis–NIR spectroscopy, SEM, Laser particle size analysis, and accelerated/outdoor weathering. The optimal composition, YIn 0.8 Mn 0.2 O 3, is comparable to standard CoAl 2 O 4 pigments, for example, having similar CIE color L* (∼34) and b* (∼-39) values, and increased a* (∼10) values in an acrylic coating. The potential utility of YIn 0.8 Mn 0.2 O 3 as an industrial pigment was demonstrated by 5000 h of accelerated QUV weathering (ΔE* = 0.5) and 48 months of Cincinnati, Ohio outdoor exposure (ΔE* = 1.1) in which the performance was comparable or improved compared to CoAl 2 O 4 . The increased UV absorbance measured by thin film absorptivity, and decreased heat buildup determined from PVC spectral properties demonstrate that the YInO 3 – YMnO 3 materials offer a robust and ‘cool’ cobalt-free alternative to CoAl 2 O 4 pigments. [ABSTRACT FROM AUTHOR]

Pigments from the LaAl 1−x Fe x O 3 (x = 0.00 to 1.00) system were synthesized through the citrate method and thermally treated at 910 °C for 4 h. The samples obtained were characterized through X-ray diffraction (XRD), Mössbauer spectroscopy (MS), field effect scanning electronic microscopy (FE-SEM), energy dispersive spectroscopy (EDS) and diffuse reflectance spectroscopy in the UV–Visible (DRS UV–Vis). The XRD analysis revealed the formation of perovskite as a single phase, crystallizing in the rhombohedral crystalline system with values 0.00 ≤ x ≤ 0.80, and in the orthorhombic system with x > 0.80 value. Through the Mössbauer spectroscopy, it was possible to follow the phase transformation and determine at which iron concentrations the coexistence of the perovskite rhombohedral and orthorhombic phases occurred. The electronic microscopy enabled to identify that the pigments presented particles of ideal size to be applied as ceramic pigments. Regarding coloration, the increase in Fe 3+ concentration in the LaAl 1−x Fe x O 3 system provoked lattice distortions, altering the pigment band gap values and consequently their color. The pigments obtained presented coloration varying from white (LA), greenish-yellow (LAF1 to LAF5) and orange (LAF6 to LF). The pigments were applied to the enameling of ceramic pieces at 850 °C, decorative burning temperature and presented good color and opacity. Thus, the system under study presented suitable properties to be used as pigment to ceramic and polymer, in addition to presenting low toxicity, a fundamental characteristic in the current scenery of environmental and human health concerns. [ABSTRACT FROM AUTHOR]

The analysis of 28 specimens of some of the first Portuguese postage stamps, dated from 1853 to 1894, was undertaken with non-destructive techniques: X-Ray fluorescence (XRF), Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and Ultraviolet–Visible Reflectance Spectroscopy (UV–Vis). Ink, paper and cancellation of the postage stamps were analysed, and the pigments, binders and fillers identified. Prussian blue was found present in all blue and also in green and brown specimens. Chrome and zinc yellow, lead sulphate and mars red were also found in other of the investigated postage stamps. Binders consist mostly of protein glue. Fillers such as calcite and kaolinite were found dominant. The presence of the latter served as an indicator for distinguishing between genuine and forged samples. UV–Vis spectra also proved useful for the same purpose. All the above information was processed and organized using chemometric techniques. These include mainly Hierarchical Cluster Analysis (HCA), for clustering stamps of similar composition, and Principal Component Analysis (PCA) for mapping the samples and identifying the more relevant variables. The latter are, in the paper, content of calcium, potassium, sulphur and silicon and, in the dye pigment area, of iron, zinc and lead content. The study introduces an approach in which, by combination of non-destructive multi analytical techniques with chemometric analysis, extensive information on different aspects of the composition of the studied postage stamps is provided, including that of paper and dyes. [Display omitted] • Non-destructive techniques are clearly able to identify components of postage stamp. • Prussian blue was found in most of the samples, blue or otherwise. • Forged and genuine samples could be distinguished. • Chemometric techniques guided the interpretation of the results. [ABSTRACT FROM AUTHOR]

Most of panel paintings in Cambodia were destroyed by climate, insects and war; especially during Khmer Rouge (1975–1979). A few paintings were studied for materials and techniques. In this research, we focus on the pigment analyses of the early 20th century Cambodian panel paintings on the wooden doors and windows in the gallery of bronze, National Museum of Cambodia. The EDX and XRD techniques were applied to determine the elemental compositions and identities of the pigments used in the paintings. The results suggested the presence of lead white, calcite, Prussian blue, red cinnabar, red ochre, red lead, gypsum, emerald green (clinoclase), organic black, organic brown with the base of blanc fixe and gold leaf in the paintings. The cross sections of paint samples showed various layers; wood support, ground and paint layers. The ground layer was composed of kaolin while various white pigments like calcite, lead white, blanc fixe and gypsum were found in the paint layer. This indicated the use of white pigment(s) in combination with another colored pigment(s). • Most of Khmer panel paintings were destroyed by climate, insects and war. • White lead, cinnabar, emerald green, red lead, hematite, barium sulfate, calcite and gypsum were evidenced by XRD. • Kaolin was used as the ground layer in the paint samples. [ABSTRACT FROM AUTHOR]

Natural pigments are a group of chemically heterogeneous molecules that occur across several taxonomical groups. Due to the remarkable chemistry of marine organisms, many species exhibit a wide-range of colours, many of which display several biological properties and constitute an evolutionary adaptation.In this work we review the state of the art regarding pigments from marine invertebrates, with special attention being given to the chemistry and distribution of these molecules, as well as relevant instrumental techniques for their analysis, such as LC-MS and HPLC-DAD. Some of the classes covered include tetrapyrroles, carotenoids, azulenes, indigo and quinones. [ABSTRACT FROM AUTHOR]

A library of closely related diacetylenes has been synthesised, comprising docosa-10,12-diynediamides with small n -alkyl or cycloalkyl substituents on the termini. Colour changes of these solids in response to ultraviolet (UV) radiation and heating were analysed using a range of analytical techniques, including UV–visible/near-infrared reflectance, hand-held Raman and solid-state nuclear magnetic resonance (ssNMR) spectroscopies. Colorimetric studies showed that this class of diacetylene undergoes clear colour changes that are very sensitive to even small alterations in molecular structure. The colour change transitions of diacetylenes bearing either cyclopentyl or cyclohexyl substituents were more similar to each other than to those of analogous diacetylenes bearing either n -pentyl or n -hexyl substituents. Differential scanning calorimetry (DSC) also reflected these differences, with the cycloalkyl substituted diacetylenes showing endothermic transitions at significantly higher temperatures than both acyclic analogues. From this library, an n -hexyl substituted diacetylene shows the greatest potential as a colour change pigment, with three distinct colours that are stable at room temperature (white, blue, red), as well as an unstable yellow colour at elevated temperatures. The colour change properties of a family of simple diacetylenes are very sensitive to small differences in structure. [Display omitted] • Four diacetylenes with analogous alkyl substituents have been synthesised. • Diacetylene colour changes were analysed using multiple spectroscopic techniques. • Diacetylene colour change properties were sensitive to small differences in structure. • One diacetylene material gives stable white, blue and red colours. [ABSTRACT FROM AUTHOR]