Yellow Crystals Research Articles

Uranoclite, a new uranyl chloride mineral from the Blue Lizard mine, San Juan County, Utah, USA

AbstractThe new mineral uranoclite (IMA2020-074), (UO2)2(OH)2Cl2(H2O)4, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as tightly intergrown aggregates of irregular yellow crystals in a secondary assemblage with gypsum. The streak is very pale yellow and the fluorescence is bright green–white under 405 nm ultraviolet light. Crystals are translucent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ~1½, the fracture is irregular. The mineral is soluble in H2O and has a calculated density of 4.038 g⋅cm–3. Electron microprobe analyses provided (UO2)2(OH)2.19Cl1.81(H2O)4. The six strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 8.85(38)(002), 5.340(100)(200, 110), 5.051(63)($\bar{2}$02), 4.421(83)(112, 004, 202), 3.781(38)($\bar{2}$12) and 3.586(57)(014, $\bar{2}$04). Uranoclite is monoclinic, P21/n, a = 10.763(8), b = 6.156(8), c = 17.798(8) Å, β = 95.656(15)°, V = 1173.5(18) Å3 and Z = 4. The structure is the same as that of synthetic (UO2)2(OH)2Cl2(H2O)4 in which the structural unit is a dimer consisting of two pentagonal bipyramids that share an equatorial OH–OH edge. The dimers are linked to one another only by hydrogen bonding. This is the second known uranyl mineral containing essential Cl and the first in which Cl coordinates to U6+.

Synthesis of Highly-Oriented Black CsPbI3 Microstructures for High-Performance Solar Cells

Synthesis of a thin layer of perovskite with less pinholes and defects is vital for the construction of a high-performance perovskite solar cell (PSC). We report on an oriented attachment strategy to fabricate a black phase CsPbI3 highly oriented quasi-single-crystalline microstructure film for constructing a mesoporous PSC device with enhanced power conversion efficiency, from 13.4% to 16.0%. The theoretical calculations and detailed in/ex situ characterizations demonstrate that the oriented attachment is driven by the predominant adsorption of dimethyl sulfoxide (DMSO) on the {212} facets of the yellow phase δ-CsPbI3 crystals which initially form a relatively oriented structure followed by phase transition to α-CsPbI3 crystals and merging into a large highly oriented quasi-single-crystalline microstructure film with {200} planes exposed under annealing. Our work demonstrates that the oriented attachment strategy enables the formation of highly oriented quasi-single-crystalline perovskite microstructure films which are essential for realizing high-efficiency and stable thin film PSCs.

<p><strong>A new species of <em>Wrightoporia</em> (Wrightoporiaceae, Basidiomycota) from Sri Lanka</strong></p>

A new resupinate polypore, Wrightoporia srilankensis sp. nov., is described from Sri Lanka. It is characterized by annual resupinate basidiocarps with buff yellow pores, margin and subiculum with rhizomorphs, a dimitic hyphal structure with yellowish crystals on both generative and skeletal hyphae, generative hyphae bearing clamp connections, dextrinoid and cyanophilous skeletal hyphae, the absence of gloeoplerous hyphae and gloeocystidia, and broadly ellipsoid, hyaline, thick-walled, finely asperulate, strongly amyloid, cyanophilous basidiospores measuring 3.8–4.2 × 2.8–3.2 µm. Molecular phylogenetic analyses based on ITS and nLSU rDNA sequences confirmed that W. srilankensis nested in the Wrightoporia clade. W. srilankensis is closely related to Wrightoporia avellanea which, however, lacks cystidioles, and its hyphae are smooth (without crystals).

Solid-State Fluorophore Based on π-Extended Heteroaromatic Acceptor: Polymorphism, Mechanochromic Luminescence, and Electroluminescence

A novel light-emitting material 4-(4-diphenylaminophenyl)-benzo[d,e]benzo[4,5]imidazo[2,1-a]isoquinolin-7-one (4-TPA-BBI) is synthesized and characterized. 4-TPA-BBI exhibits excellent polymorphism, mechanochromic luminescence (MCL), and electroluminescence properties. It can form three different aggregate species: yellow rod-like crystal (Y-crystal), orange needle-like crystal (O-crystal), and red solid (R-solid). It is observed that the Y-crystal can be reversibly changed to R-solid upon external stimuli, while O-crystal can be irreversibly transformed to R-solid via sublimation under a vacuum. Crystallographic and photophysical studies indicate that the Y-crystal featuring loose molecular packing demonstrates a high photoluminescence quantum yield (ΦPL ≈ 1) and obvious MCL property, while the compactly packed O-crystal shows a lower ΦPL of 0.646 with negligible MCL. A nondoped light-emitting device based on 4-TPA-BBI as an emitter exhibits bright orange emission with a peak at 588 nm, a high external quantum efficiency of 4.4%, and a maximum luminance of 22470 cd m–2.

Role of Anions and Mixtures of Anions on the Thermochromism, Vapochromism, and Polymorph Formation of Luminescent Crystals of a Single Cation, [(C6H11NC)2Au

Noncoordinating anions, which generally play a subordinate role in coordination chemistry, alter the structure, the luminescence, as well as the thermochromic and vapochromic behaviors of salts of the two-coordinate cation, [(C6H11NC)2Au]+. Thus whereas the yellow polymorphs of [(C6H11NC)2Au](PF6) and [(C6H11NC)2Au](AsF6) contain single chains of cations and are vapochromic, yellow [(C6H11NC)2Au](SbF6) does not form the same polymorph and is not vapochromic but contains two distinct chains of cations connected through aurophilic interactions. Mixed crystals such as [(C6H11NC)2Au](PF6)0.50(AsF6)0.50 have been prepared by adding diethyl ether to a dichloromethane solution containing equimolar amounts of [(C6H11NC)2Au](PF6) and [(C6H11NC)2Au](AsF6). The initial (kinetic) product for the three combinations of anions ((PF6)-/(AsF6)-, (PF6)-/(SbF6)-, and (AsF6)-/(SbF6)-) was a precipitate of fine yellow needles with a green emission, which were gradually transformed at rates that depended on the anions present into colorless crystals with a blue emission. Whereas neither polymorph of [(C6H11NC)2Au](PF6) nor [(C6H11NC)2Au](SbF6) is thermochromic, the colorless mixed crystal [(C6H11NC)2Au](PF6)0.50(SbF6)0.50 is thermochromic and converts from blue-emitting to green-emitting at 87-95 °C. The temperature required to transform a crystal of the type [(C6H11NC)2Au](PF6)n(AsF6)1-n from colorless (blue-emitting) to yellow (green-emitting) increases as the fraction of hexafluorophosphate ion in the crystal increases. The yellow crystals of [(C6H11NC)2Au](PF6)0.75(AsF6)0.25, [(C6H11NC)2Au](PF6)0.50(AsF6)0.50, and [(C6H11NC)2Au](PF6)0.25(AsF6)0.75 are vapochromic, whereas the yellow crystals of [(C6H11NC)2Au](PF6)0.50(SbF6)0.50 and [(C6H11NC)2Au](AsF6)0.50(SbF6)0.50 are not.

Strongly Emissive Lead‐Free 0D Cs3Cu2I5 Perovskites Synthesized by a Room Temperature Solvent Evaporation Crystallization for Down‐Conversion Light‐Emitting Devices and Fluorescent Inks

AbstractLead‐free 0D metal halide perovskites are emerging environmentally friendly materials exhibiting large exciton binding energy, which have recently attracted great attention for their excellent light emission properties and favorable stability. Herein, solvent evaporation crystallization at room temperature is adopted to fabricate 0D Cs3Cu2I5 perovskite millimeter‐sized crystals, which show strong blue photoluminescence (PL) with quantum yield of up to 89%, a large Stockes shift and long (microsecond) PL lifetime, originating from self‐trapped excitons. UV pumped light‐emitting diodes are demonstrated by using Cs3Cu2I5 powder as a solid‐state phosphor, and the precursor solution of these perovskite crystals is used as a fluorescent ink. Furthermore, blue‐emitting composite Cs3Cu2I5/polyvinylidene fluoride films are produced by spin coating through the solvent evaporation and followed patterning using a direct laser writing technology, which are potentially useful for displays. Finally, the solvent evaporation crystallization method is expanded to fabricate yellow emissive CsCu2I3 crystals by changing the chemical molar ratio of precursor.

Therapeutic potential of xanthones from Swertia chirata in breast cancer cells.

Background & objectives:Medicinal plants like Swertia chirata are rich sources of different xanthones. This study was aimed to assess the cytotoxic potential of four most abundant xanthones present in S. chirata both in vivo and in vitro in Ehrlich ascites carcinoma (EAC), a mouse transplantable breast carcinoma cell line and two human breast carcinoma cell lines (MCF-7 and MDA-MB-231).Methods:Four xanthones derived from S. chirata namely 1-hydroxy-3,7,8-trimethoxyxanthone (XA), 1,8-dihydroxy-3,5-dimethoxyxanthone (XB), 1-hydroxy-3,5,8-trimethoxyxanthone (XC) and 1,5,8-trihydroxy-3-methoxyxanthone (XD) were used for determination of sub-lethal dose on the cell lines EAC, MCF-7, MDA-MB-231 and verified toxicity of sub-lethal dose on normal murine fibroblast cells. Cytotoxicity was measured in vivo and survivability of mice was plotted accordingly. Therapeutic efficacy of XD was evaluated both in vivo and in vitro by determination of lipid peroxidation (LPO), reactive oxygen species (ROS) generation and by quantitating the enzyme status (GSH, catalase, superoxide dismutase) in treated and untreated samples. DNA damage was evaluated using comet and DNA fragmentation assays. Furthermore, apoptotic effect was analyzed by flow cytometry and validated by TUNEL assay and Western blotting.Results:Among all the xanthones tested XD showed IC50 at the lowest dose, and normal cells were unaffected at this dose. Survivability of mice increased significantly when treated with XD compared to other xanthones and cisplatin. Significantly increased ROS and LPO were found in cancer cells as a result of XD treatment which was unaltered in normal cell line. XD induced DNA damage and apoptosis in cancer cell lines.Interpretation & conclusions:Our experimental data indicate that XD may potentially act as a chemotherapeutic agent by enhancing ROS in breast cancer cells thereby leading to apoptosis.

Synthesis and antibacterial activity of 4-piperidone curcumin analogues against gram-positive and gram-negative bacteria

The rapid development of antibiotics resistance makes antibiotics become less effective for the treatment of bacterial infections. Accordingly, it is so important to discovery and development of new antibacterial agents. Three 4-piperidone curcumin analogues (3,5-bis-(2-chlorobenzylidene)-4-piperidone (1), 3,5-bis-(4-chlorobenzylidene)-4-piperidone (2) and 3,5-bis-(2,4-dichlorobenzylidene)-4-piperidone (3) were synthesized from 4-piperidone monohydrate hydrochloride with 2-chlorobenzaldehyde, 4-chlorobenzaldehyde and 2,4-dichlorobenzaldehyde. The Claisen-Schmidt condensation reaction was used in acid condition. All the compounds showed light yellow crystal with percentage of yield 39, 41 and 34% respectively. All the structure compounds were confirmed by using IR, 1H-NMR, 13C-NMR, and MS. The evaluation of antibacterial activity conducted by Agar diffusion method against Gram-positive bacteria such as Bacillus subtilis (ATCC 6633) and Enterococcus faecalis (ATCC 29212), and Gram-negative bacteria such as Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853). The result showed that all the compounds showed significant activity but they were more effective against Gram-positive bacteria as compared to their Gram-negative counterparts. Analogues curcumin compound showed that there was antibacterial activity up to concentration 62,5 μg/mL on Gram positive bacteria and 125 μg/mL on Gram negative bacteria. The compound 3,5-bis-(2,4-dichlorobenzylidene)-4-piperidone (3) containing two substituent -Cl on ortho and para position in the benzene ring has best activity than compound 1 and 2.

Donor-acceptor π-conjugated quinoxaline derivatives exhibiting multi-stimuli-responsive behaviors and polymorphism-dependent multicolor solid-state emission

Two phenothiazine-based quinoxaline derivatives QPT1 and QPT2 have been rationally designed and synthesized. Optical analysis and theoretical chemical calculations illustrated that they showed typical intramolecular charge transfer (ICT) process from electron-rich phenothiazine unit to electron-withdrawing quinoxaline moiety. Interestingly, QPT1 exhibited the polymorphism feature and high-contrast mechanochromic luminescence. Two types of crystals were prepared by solvent evaporation method. A green needle-like crystal (G-form) and a yellow ribbon-like crystal (Y-form) were yielded from dichloromethane/petroleum ether and THF solution, respectively. The emission peaks of G-form and Y-form in pristine powders appeared at 501 nm and 549 nm, and red-shifted to 570 nm and 594 nm in ground powders, respectively, giving the emission spectral shifts of 69 nm for G-form and 45 nm for Y-form. Besides, QPT2 exhibited moreover autonomously self-recovering mechanochromic luminescence. X-ray diffraction measurements confirmed that the reversible phase transition between the crystalline and amorphous states has been proposed as the MFC mechanism. Moreover, QPT1 and QPT2 also showed stable acidofluorochromic characteristics. The solution and film of QPT1 and QPT2 achieved a fast response to TFA with high sensitivity and low detection limit. The multiple stimuli responsive performances of QPT1 and QPT2 make them potential candidates for smart materials.

Dyeing to be sustainable

Industrial dyes come primarily from nonrenewable materials like coal tar. Plant-derived dyes present an attractive alternative but are expensive and resource intensive, and they often don’t work as well as their synthetic cousins. Seeking to make a more sustainable synthetic dye, chemist Mark Mascal and colleagues at the University of California, Davis, have synthesized yellow, orange, and red dyes using compounds derived from cellulose and lignin components (Angew. Chem., Int. Ed. 2019, DOI: 10.1002/anie.201911387). The team got the idea after reading a 1911 report of canary-yellow crystals that formed from the reaction of 5-(bromomethyl)furfural with barium carbonate in hot water (J. Chem. Soc., Trans., DOI: 10.1039/CT9119901193). Mascal’s group had been working with a related compound, 5-(chloromethyl)furfural (CMF), which can be made in high yield from raw biomass. The group found that CMF also produced yellow crystals in the presence of barium carbonate and hot water. Once they determined what molecule

Synthesis of (2Z)-4,6-Diphenyl-N-((2-(Piperidin-1-yl)Ethyl]-2H-1,3-Thiazin-2-Imino Hydrochloride and its Antimicrobial Activities

Aim: The study aims to synthesize, characterize, and screen (2Z)-4,6-diphenyl-N-((2-(piperidin-1-yl)ethyl]-2H-1,3-thiazin-2-imino hydrochloride for microbial activities.
 Methodology: A (2Z)-4,6-diphenyl-N-((2-(piperidin-1-yl)ethyl]-2H-1,3-thiazin-2-imino hydrochloride was synthesized via two-steps reaction from chalcone using acetophenone and benzaldehyde, further cyclized with thiourea and later N-alkylated with 1-(2-chloroethyl)piperidine hydrochloride, its purity was tested by thin-layer chromatography (TLC) and characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (NMR) and nuclear magnetic resonance (13C-NMR) and screened against Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis, methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Candida albicans using the standard microbiological method.
 Results: A golden yellow needle-like crystals (2Z)-4,6-diphenyl-N-((2-(piperidin-1-yl)ethyl]-2H-1,3-thiazin-2-imininium hydrochloride with Rf, 7 EtOAc: 3 Pet (0.75) and MP, 285-287oC was synthesized and the in vitro antimicrobial study of the compound exhibited moderate activities in comparison with standard ciprofloxacin and itraconazole.
 Conclusion: A new (2Z)-4,6-Diphenyl-N-((2-(piperidin-1-yl)ethyl]-2H-1,3-thiazin-2-imininium hydrochloride was synthesized using Claisen-Schmidt condensation, Michael addition and N-alkylation shows moderate antimicrobial activities against E. coli, B. subtilis, methicillin-susceptible S. aureus, methicillin-resistant S. aureus and C. albicans.

Synthesis, Structural Characterization and Ligand-Enhanced Photo-Induced Color-Changing Behavior of Two Hydrogen-Bonded Ho(III)-Squarate Supramolecular Compounds.

Two coordination polymers (CPs) with chemical formulas, [Ho2(C4O4)2(C2O4)(H2O)8]·4H2O (1) and [Ho(C4O4)1.5(H2O)3] (2), (C4O42− = dianion of squaric acid, C2O42− = oxalate), have been synthesized and their structures were determined by single-crystal X-ray diffractometer (XRD). In compound 1, the coordination environment of Ho(III) ion is eight-coordinate bonded to eight oxygen atoms from two squarate, one oxalate ligands and four water molecules. The squarates and oxalates both act as bridging ligands with μ1,2-bis-monodentate and bis-chelating coordination modes, respectively, connecting the Ho(III) ions to form a one-dimensional (1D) ladder-like framework. Adjacent ladders are interlinked via O–H⋅⋅⋅O hydrogen bonding interaction to form a hydrogen-bonded two-dimensional (2D) layered framework and then arranged orderly in an AAA manner to construct its three-dimensional (3D) supramolecular architecture. In compound 2, the coordination geometry of Ho(III) is square-antiprismatic eight coordinate bonded to eight oxygen atoms from five squarate ligands and three water molecules. The squarates act as bridging ligands with two coordination modes, μ1,2,3-trismonodentate and μ1,2-bis-monodentate, connecting the Ho(III) ions to form a 2D bi-layered framework. Adjacent 2D frameworks are then parallel stacked in an AAA manner to construct its 3D supramolecular architecture. Hydrogen bonding interactions between the squarate ligands and coordinated water molecules in 1 and 2 both play important roles on the construction of their 3D supramolecular assembly. Compounds 1 and 2 both show remarkable ligand-enhanced photo-induced color-changing behavior, with their pink crystals immediately turning to yellow crystals under UV light illumination.

Crystal growth and 570 nm emission of Dy3+ doped CeF3 single crystal

A Dy3+-doped CeF3 yellow region laser crystal was successfully grown using the Bridgman method. A 570 nm emission in Dy:CeF3 crystal was observed for the first time. By analyzing the absorption and emission measurements of the Dy:CeF3 crystal with the Judd–Ofelt theory, the intensity parameters Ω2,4,6, exited state lifetimes, branching ratios, and emission cross-sections were calculated. It is found that the Dy:CeF3 crystal has high emission cross section (0.9259 × 10−20 cm2) and long fluorescence lifetime (1.53 ms) corresponding to the stimulated emission of Dy3+:4F9/2 → 6H13/2 transition. We propose that the Dy:CeF3 crystal may be a promising material for 570 nm laser applications.

A Gold Quartet Framework with Reversible Anisotropic Structural Transformation Accompanied by Luminescence Response

Summary Hierarchy and chirality are the fundamental characteristics of biomolecules. Chemistry on hierarchical self-assembly and spontaneous symmetry breaking helps to uncover the mechanism of living activities and the origin of chirality in nature. Herein, we describe a chiral gold quartet framework (GQF) with C4-symmetric structure hierarchically aggregated from an achiral anionic [Au10(dpptrz)4S4]2− (dpptrz-Au10), which was acquired via click-reaction-induced and Au(I)⋅⋅⋅Au(I)-interaction-directed cluster-to-cluster transformation (CCT) from the rationally designed [(dppa)6Au18S8]2+ (dppa-Au18). Inter-cluster hydrogen bonding and alkali ion coordination were observed to assist the hierarchical self-assembly and chiral self-organization of the GQF. Upon exposing the crystal to vacuum, the bottom-up constructed GQF showed an anisotropic structural transformation accompanied by a visual luminescence change in a single-crystal-to-single-crystal (SCSC) manner that became reversible upon removal of vacuum. This research largely advances the potential of polynuclear gold(I)-sulfido clusters in hierarchical self-assembly and luminescent materials.

Synthesis, structure and physico-chemical properties of two uranyl complexes of cucurbiturils mediated by sulfate ions

In this article, with the aid of additional ligands, (UO2)2(CB5)(SO4)2(H2O)2•5H2O ( U-CB5-SO 4 ) and (UO2)-(CB6)0.5(SO4)(H2O)•4H2O ( U-CB6-SO 4 ) were synthesized by hydrothermal method at high temperature. Their structures and physico-chemical properties were characterized by a combination of single-crystal X-ray diffraction, PXRD, TG-DSC, FTIR, UV-Vis and fluorescence spectra. U-CB5-SO 4 crystalized in orthorhombic system, and space group Pnma , while U-CB6-SO 4 crystalized in monoclinic system and space group I2/m . U-CB5-SO 4 forms a yellow windmill-like poly crystal, while U-CB6-SO 4 forms a yellow stick-like single crystal.

Synthesis of 2-methyl-5-methoxy-1,4-benzoquinone and In-silico Activity Profiling Toward Cytochrome P450-3A4

The synthesis of 2-methyl-5-methoxy-1,4-benzoquinone (2) was carried out by reflux of 2-methyl-1,4-benzoquinone (1) with MeOH and ZnCl2 for 12 hours at ambient. The reaction resulted a yellow needle crystal in 6.92 % yield (m.p 173-175°C). The FT-IR analysis showed the presence of -OCH3 group at 1210 cm−1. The analysis using 1H-NMR showed chemical shift a δ = 3.81 ppm and the 13C-NMR gave 56.38 ppm for hydrogen and carbon from -OCH3 group. The bioavailability tests were determined by using in silico approach included lipophilicity (log P) and half maximum inhibitory concentration (IC50). It showed that the lipophilicity of 2 (log P = 0.92) is lower than 1 (log P = 1.79) which is calculated using Hyperchem software. The molecular docking of 2 towards cytochrome P450-3A4 showed a good result with IC50 13.68 ppm better than 1 (IC50 65.617 ppm). Further experimental is proposed for bromoalkylation of 2 using bromooctanoic acid to give 3-(7-bromoheptyl)-2-methyl-5-methoxy-1,4-benzoquinone (3). The in-silico calculation of 3 showed better lipophilicity (log P = 3.64) and IC50 (9.725 ppm) compared to 2. This result indicated that the addition of methoxyl and bromoalkyl group can improve the activity of the compound as a drug candidate.

The role of pyrite in fossilisation and its potential instability

Pyrite often forms in organic-rich marine sediments through bacterial action. Bacteria reduce organics to form bisulphide, which reacts in turn with dissolved iron in seawater to form pyrite. Consequently, it is frequently found in stratigraphic formations that consist of marine clays. Pyrite can be involved in fossilisation through a number of ways, including complete replacement, as infill in permineralised bone, or simply as microcrystals finely disseminated through the fossil and matrix. Replacement by pyrite can often be easily recognised: the fossil may have a gold or brassy metallic lustre. Infill is harder to recognise, and disseminated pyrite even more so. Pyrite in fossils may be stable or unstable- in its stable form, pyritised fossils will generally retain their shiny, metallic appearance. Pyrite preservation and stability can vary even within the same specimen. Fossils preserved in pyrite can be prone to oxidation, particularly at high relative humidities. There are a number of signs that indicate oxidation is occurring, depending on the severity of the condition. One or more of the following may be present: a sulphurous smell, white or yellow powdery crystals on the surface of the specimen, expansion cracks, as well as acid burns on associated labels, boxes and drawers. Such burns often have a characteristic ovoid appearance. If left unchecked, pyrite oxidation can completely destroy a specimen and its labels.

Small Structural Changes in the Alkyl Substituents of Macrocyclic π-Extended Thiophene Oligomers Causes a Key Effect on Their Stacking and Functional Properties.

Three new macrocyclic π-extended thiophene hexamers composed of four thienylene-ethynylene and two thienylene-vinylene units with or without four alkyl substituents have been synthesized. Despite similar shape-persistent structures in solution, the alkyl substituents control the solid-state structures and morphologies. The unsubstituted hexamer exhibited a planar conformation with a theoretically predicted structure in the solid state; however, the planar hexamer with four ethyl substituents formed a closely stacked columnar crystal structure to exhibit π-π interactions. Interestingly, the hexamer with four butyl substituents adopted both planar and twisted conformations in the solid state, exhibiting polymorphism based on induced-fit stacking of molecules. Thus, the butyl-substituted hexamer produces a mixture of yellow, orange, and red single crystals from toluene/acetone, and X-ray analysis revealed six different conformations. Consequently, the small structural difference in the macrocycles causes a key effect on their functional properties in the solid state, and their morphology governs electrical conductivity and organic field-effect-transistor activity. The polymorphism of the hexamers was applied to the switching of film morphology.

Preferential Orientation of Crystals and its Influence on the Emission Wavelength of Acrylonitrile Derivatives Treated with Polar Solvents

AbstractPhotoluminescence properties in solid state and its relationship with structural features of prop‐2‐enenitrile derivatives containing any of functional groups 4‐halogenphenyl, phenyl, 4‐dimethylamino, or 4‐diphenylamino are investigated. The compounds show change in color from yellow to orange after treatment with dimethyl sulfoxide or dimethyl formamide. Nevertheless, the single‐crystal X‐ray diffraction for both, the original yellow and the treated orange crystals, does not display any major structural differences. The optical properties are related to the crystal packing and intermolecular interactions such as edge‐to‐face through the vertices of aromatic rings. The last is supported by the behavior of the presence of functional group. The absorption spectrum in solution for all compounds shows two absorption bands with wavelength of maximum absorption around 390–430 nm and at 290–300 nm. Regardless of the crystal type, the maximum emission in solution was between 450–570 nm. In solid state, yellow crystals exhibit an emission in the 500–530 nm range and in the 580–630 nm range for orange crystals. Results suggest that optical properties are strongly dependent on morphology and habit. Powder X‐ray characterization shows a preferential orientation for orange crystals. All compounds are characterized by common spectroscopy techniques, fluorescence, atomic force microscopy and X‐ray diffraction.

Interaction of Na9[SbW9O33] with Iridium(IV) Hydroxo Complexes

Thermostating of the aqueous solution of Na9[SbW9O33] with K2[Ir(OH)6] at 70 °C for 17 h changes the solution’s color from blue to brown. The addition of KNO3 to the reaction solution and subsequent evaporation in air causes crystallization of the products to yield yellow crystals of composition K5.47Na2.3[Ir0.17Sb0.83W6O24](NO3)0.6·12H2O containing an Anderson-type anion $${[{\rm{S}}{{\rm{b}}^{\rm{V}}}{\rm{W}}_6^{{\rm{VI}}}{{\rm{O}}_{24}}]^{7 - }}$$ with ∼20% of antimony positions occupied by iridium.