Colorless Crystals Research Articles

Synthesis and Characterization of Strontium N,N-Dimethylaminodiboranates as Possible Chemical Vapor Deposition Precursors.

The reaction of SrBr2 with 2 equiv of sodium N,N-dimethylaminodiboranate (DMADB; Na(H3BNMe2BH3)) in Et2O at 0 °C followed by crystallization and drying under vacuum gives the unsolvated strontium compound Sr(H3BNMe2BH3)2 (1). Before the vacuum-drying step, the colorless crystals obtained by crystallization consist of the diethyl ether adduct Sr(H3BNMe2BH3)2(Et2O)2 (2). If the reaction of SrBr2 with 2 equiv of Na(H3BNMe2BH3) is carried out in the more strongly coordinating solvent thf, the solvate Sr(H3BNMe2BH3)2(thf)3 (3) is obtained. Treating the thf adduct 3 with 1,2-dimethoxyethane (dme), bis(2-methoxyethyl) ether (diglyme), or N,N,N',N'-tetramethylethylenediamine (tmeda) in thf affords the new compounds Sr(H3BNMe2BH3)2(dme)2 (4), Sr(H3BNMe2BH3)2(diglyme) (5), and Sr(H3BNMe2BH3)2(tmeda) (6), respectively, in greater than 60% yields. Treatment of 3 with 2 equiv of the crown ether 12-crown-4 affords the charge-separated salt [Sr(H3BNMe2BH3)(12-crown-4)2][H3BNMe2BH3] (7). Crystal structures of all the Lewis base adducts are described. Compounds 2-6 all possess chelating κ2-BH3NMe2BH3-κ2 groups, in which two hydrogen atoms on each boron center are bound to strontium. Compound 6 is dinuclear because each metal atom is also coordinated to one hydrogen atom on a BH3NMe2BH3- ligand that chelates to the neighboring metal center. Compound 7 possesses an unusual κ1-BH3NMe2BH3- group owing to the near-complete encapsulation of the Sr atom by two 12-crown-4 molecules; the other BH3NMe2BH3- anion is a charge-separated counterion. When they are heated, the diglyme and tmeda compounds 5 and 6 melt without decomposition and can be sublimed readily under reduced pressure (1 Torr) at 120 °C. The diglyme and tmeda adducts are some of the most volatile strontium compounds known and are promising candidates as CVD precursors for the growth of strontium-containing thin films.

Antibacterial activity of isolated compounds from the stem bark of Calophyllum euryphyllum

Calophyllum euryphyllum Lauterb (Clusiacea family) has the potential as material for medical industries. To continue our drug discovery of the Indonesian plant, we chose C. euryphyllum species for antibacterial sources. Semi polar extract from C. euryphyllum was prepared and purified by column chromatographic methods and then identified by spectroscopic methods (LC-MS-MS, IR, UV, and 1H-NMR and 13C-NMR). The pure isolated compound was subjected to antibacterial activities by using E. coli. S.aureus, and B. subtilis. Semi polar fraction of C. euryphyllum showed the antibacterial activity against E. coli. S.aureus and B.subtilis with MIC about 2.05%, 2.82%, 1.54% for E. coli. S.aureus and B.subtilis, respectively. One compound was isolated from the semi-polar fraction of the stem bark C. euryphyllum. It was identified as a triterpene (with molecular weight 438), a colorless crystal with a melting point was 133-134 °C, and the molecular formula was C30H46O2.

Metallographic Documentation of the Degradation of Iron and Nickel Based Alloys in HCl and H<sub>2</sub>S Containing Environments, between 480 – 680 °C

Corrosion behavior of the alloys 1.7386 (P9), 1.4462, 1.4841, 1.4959 (Alloy 800HT) and 2.4816 (Alloy 600) was tested for 24, 72 and 240 h between 480 – 680 °C. The testing gas atmosphere contained 3.8 vol. % HCl, 200 ppm H2S and CO, CO2 and N2. It simulated conditions present in a thermal cracking process for post-consumer plastics. Samples were analyzed by metallography, SEM/EDX and XRD after corrosion experiments. Additionally, their mass loss during the test was evaluated. A multilayered structure of corrosion products grew on the samples during the corrosion experiments. The composition of the corrosion products depended not on the material, but on the testing temperature. At 680 °C chromium sulphide formed the outer layer, followed by a chromium oxide layer. Below these two layers a chlorine containing layer was observed. At 480 °C mainly nickel sulphide was detected, besides chromium oxide and iron- and chromium chloride. Especially at higher testing temperatures FeCl2 was not observed directly on the samples, but as colorless crystals at the colder parts of the testing equipment. At 680 °C the mass loss of the samples decreased with increasing nickel content. However, this effect changed entirely at lower testing temperatures. At 480 °C 1.7386 and 2.4816 showed nearly the same mass losses.

The Neutral Complex (NH3)Ag(NCO)

Dissolution of solid AgNCO (silver isocyanate) in aqueous ammonia (25 %) and subsequent crystal growth at T = –9 °C furnished the new ammoniate (NH3)Ag(NCO) as colorless crystals [P21/c (no. 14); a = 4.1817(3) Å, b = 14.445(1) Å, c = 6.1988(5) Å, β = 102.0(4)°, V = 365,6(2) Å3; Z = 4]. In the molecular monammine complex, which is only stable at temperatures below T = 0 °C, silver is in a twofold, however, asymmetrical coordination by the isocyanate anion and ammonia. At the reaction conditions applied, AgNCO does not form an ionic diammine species (e.g. [Ag(NH3)2]+) as known from related silver salts. In this sense, the solvation chemistry of AgNCO exhibits a rarely observed feature.

Solid‐State Preparation and Luminescence Investigation of Rare Earth Iodide Carbodiimide Nitrides RE2I(CN2)N (RE = La, Gd) and LaI(CN2)

New rare earth iodide carbodiimide nitride compounds with the composition RE2I(CN2)N (RE = La, Gd) were successfully synthesized by multilateral solid‐state metathesis reaction from RE triiodides, LiN and Li2(CN2). The crystal structures of RE2I(CN2)N were refined from X‐ray powder diffraction data with the space group Cmmm. LaI(CN2) was prepared from a mixture of LaI3 and Li2(CN2). The crystal structure was determined by X‐ray single‐crystal diffraction on a colorless crystal with the orthorhombic space group Cmcm. The luminescence investigation of Ce3+‐doped LaI(CN2) was carried out by excitation at 390 nm and reveals a broad emission band in the blue range of the visible spectrum.

Structurally characterized new alkyl- and alkenyl-gallium peroxides having interesting structural motifs

Reaction of lithium gallium hydride, LiGaH4, with one equivalent of tert-butyllithium generated lithium(tert-butyl)trihydridogallate, Li[tBuGaH3] (1), as colorless solid via LiH elimination. Treatment of 1 with four equivalents of tert-butyl hydrogenperoxide and subsequent crystallization generated few colorless crystals at -35 °C. Single crystal X-ray diffraction study showed the formation of a (tert butyl) galliumperoxide [tBu-Ga(OOtBu)2O(H)-Li(HOtBu)2]2 (2) where a strongly reducing “tBu-Ga” group is situated intact to two strongly oxidizing “Ga-O-O-tBu” moieties. Further, two such alkyl-galliumperoxo units dimerizes through hydroxolithium bridges. A close look at the single crystal X-ray structure of 2 show the presence of strong hydrogen bonding interactions between the peroxide oxygen and hydroxy group of tert-butanol, which are coordinated to the lithium ions. Similarly, the first alkenyl-gallium peroxide was generated via reaction of [Ph-CH=C(SiMe3)GaH2tBuLi] (3) with three equivalent of tert-butyl hydrogen peroxide. Single crystal X-ray diffraction study showed the formation of an alkenyl-gallium peroxide [Ph-CH=C(SiMe3)Ga(OOtBu)3Li]2 (4) via elimination of two equivalents of hydrogen and one equivalent of isobutane where three tert-butylperoxo groups along with an alkenyl group are attached concurrently to a single gallium atom. In addition, each of the lithium atoms are coordinated with four different oxygen atoms of two different peroxide groups.

Optical property in colorless AlN bulk crystals: investigation of native defect-induced UV absorption

The 4.7 eV absorption band of colorless AlN crystal with the carbon concentration level of 107 cm−3 is investigated. An analysis of the absorption characteristics of the annealed AlN crystal indicates that the native defect is the origin of 4.7 eV absorption band and gives rise to an infrared absorption band at 2850 cm−1. The theory calculations predict two absorption bands at 4.65 eV and 0.35 eV of nitrogen vacancy, and the defect explains the increased and decreased intensity of infrared absorption band at 2850 cm−1 as well as a similar increased-decreased ultraviolet absorption band at 4.7 eV.

The complete series of sodium rare-earth metal(III) chloride oxotellurates(IV) Na2 RE 3Cl3[TeO3]4 (RE = Y, La–Nd, Sm–Lu)

Abstract The complete series of sodium rare-earth metal(III) chloride oxotellurates(IV) with the composition Na2 RE 3Cl3[TeO3]4 (RE = Y, La–Nd, Sm–Lu) has been synthesized via solid-state reactions. For these conversions mixtures of the respective rare-earth metal(III) oxides, tellurium dioxide and sodium chloride as flux and reactant were prepared, intimately ground and heated for 5 days at 1225 K. The almost colorless single crystals were characterized via single-crystal X-ray diffractometry. In the monoclinic crystal structure of these compounds two crystallographically different rare-earth metal(III), but only one sodium cation sites occur. [REO8]13− polyhedra around both RE 3+ positions as well as sodium-centered polyhedra [NaO4Cl4]8− form layers via different connectivity modes. These layers spread out parallel to the (001) plane and arrange alternatingly resulting in the three-dimensional network of the Na2 RE 3Cl3[TeO3]4 structure, where the Te4+ lone-pair cations at two different sites work as linkers by forming isolated ψ 1-tetrahedra [TeO3]2−. Some of these compounds were represented before in different settings of space group C2/c. Now the complete series of the Na2 RE 3Cl3[TeO3]4 representatives with RE = Y, La–Nd, Sm–Lu is described consistently for a better comparison and understanding. Additionally, a single crystal of Na2Pr3Cl3[TeO3]4 was measured via energy dispersive X-ray analysis to verify the included elements, powder samples of Na2Nd3Cl3[TeO3]4 were characterized by X-ray diffractometer data for a phase-purity check and a single-crystal Raman spectrum of Na2Yb3Cl3[TeO3]4 served for proving the signature of discrete [TeO3]2− anions.

Novel phenoxy-(trifluoromethyl)pyridine-2-pyrrolidinone-based inhibitors of protoporphyrinogen oxidase: Design, synthesis, and herbicidal activity

As important chemical pesticides, protoporphyrinogen oxidase (PPO, EC 1.3.3.4) herbicides play a vital role in weed management. Herein, in a search for novel PPO herbicides, a series of phenoxypyridine-2-pyrrolidinone derivatives were synthesized and their herbicidal activities were tested. To confirm the structures of the newly synthesized compounds, a colorless single crystal of compound 9d was obtained and crystallographic data collected. PPO inhibition experiments showed that most compounds have PPO inhibitory effects. The half-maximal inhibitory concentration (IC50) of compound 9d and oxyfluorfen were 0.041 mg/L and 0.043 mg/L, respectively, which showed compound 9d was the most potent compound. Compound 9d reduced the Chlorophyll a (Chl a) and Chlorophyll b (Chl b) contents of Abutilon theophrasti (A. theophrasti), to 0.306 and 0.217 mg/g, respectively. Crop selectivity experiments and field trial indicated that compound 9d can potentially be used to develop post-emergence herbicides for weed control in rice, cotton, and peanut. Molecular docking studies showed that both oxyfluorfen and compound 9d can enter the PPO cavity to occupy the active site and compete with the porphyrin to block the chlorophyll synthesis process, affect photosynthesis, and eventually cause weed death. Compound 9d was found to be a promising lead compound for novel herbicide development.

Photochemically Crushable and Regenerative Metal-Organic Framework.

A photochemically crushable and regenerative metal-organic framework (DTEMOF) was developed by complexation of photochromic ligand PyDTEopen and 5-nitroisophthalate (nip2-) with Cd2+ in DMF/MeOH. DTEMOF ([Cd(nip)(PyDTEopen)(H2O)(DMF)2]n) was obtained as colorless crystals. Its crystal structure revealed that DTEMOF adopts a tubular structure with interlocked coordination networks and can accommodate guest molecules in its one-dimensional pores. When DTEMOF suspended in DMF/MeOH was exposed to UV light, its crystalline network, though thermally stable up to 260 °C, was readily crushed to afford a homogeneous blue-colored solution, via ring-closing isomerization of the constituent PyDTEopen ligand into PyDTEclosed. Upon successive exposure of this solution to visible light, colorless MOF crystals identical to those of DTEMOF were regenerated. Light-responsive DTEMOF enabled highly efficient on-demand guest release.

Layered calcium hydrogen selenite chlorides Ca(HSeO3)Cl and Ca(HSeO3)Cl(H2O), the first halides obtained in СaCl2–H2SeO3–H2O system

Abstract Synthesis, crystal structures and IR spectra of the first representatives of calcium hydrogen selenite halides are reported. Colourless prismatic crystals of calcium hydrogen selenite chloride Ca(HSeO3)Cl and corresponding hydrated analogue Ca(HSeO3)Cl(H2O) were produced upon evaporation of aqueous solutions. Ca(HSeO3)Cl is monoclinic, P21/c, a = 7.0031(11) Å, b = 7.7336(12) Å, c = 8.5024(13) Å, β = 109.889(3)°, V = 433.02(12) Å3, R 1 = 0.039. Ca(HSeO3)Cl(H2O) is orthorhombic, Pbca, a = 6.222(4) Å, b = 10.413(7) Å, c = 16.875(10) Å, V = 1093.3 (12) Å3, R 1 = 0.041. Ca(HSeO3)Cl and Ca(HSeO3)Cl(H2O) represent new structure types. In both structures, Ca2+ cations adopt mixed-ligand environments formed by oxygen atoms of hydrogen selenite anions (and water molecules for Ca(HSeO3)Cl(H2O)) and chloride ions. Both structures are layered. The crystal structure of Ca(HSeO3)Cl(H2O) demonstrates a rare phenomenon of hydrogen-bonded assembly of water and chloride in the interlayer space.

S-Block metal scorpionates – A new sodium hydrido-tris(3,5-dimethyl-1-pyrazolyl)borate salt showing an unusual core stabilized by bridging and terminal O-bonded DMSO ligands

Abstract Dissolution of [(μ-Me2CO)3(NaTp*)2] (1) (Tp* = hydrido-tris(3,5-dimethyl-1-pyrazolyl)borate) in DMSO at room temperature leads to the growth of colourless crystals characterized as the new salt [Na2Tp*(μ-Me2SO)3(Me2SO)3] [NaTp* 2] (2). 2 crystallized in the trigonal space group R3 with Z = 3, a = 14.1227(2) Å, b = 14.1227(10) Å, c = 33.9685(2) Å, and V = 5867.35(17) Å3. Interestingly, anion and cation of 2 both contain the Tp* ligand. Moreover, the cationic moiety highlights an unusual sodium atom hexacoordinated by six DMSO molecules acting as O-bonded ligands. Three of which exhibit a bridging coordination mode and three are in terminal position. To the best of our knowledge, the framework of [Na2Tp*(μ-Me2SO)3(Me2SO)3] is unprecedented.

Some Complementary Data about the Spectroscopic Properties of Manganese Ions in Spodumene Crystals

The color change of the pink and colorless LiAlSi2O6 spodumene crystal due to irradiation and heating is explained. The hypothesis about the change of Mn3+ to Mn4+ after irradiation was rejected. For the studied crystals, it was shown that both Mn2+ and Mn3+ occupy the M2 (not the M1) crystal site. Spodumene crystals which are primary pink (kunzite) contain Mn3+ (and Mn2+) at the M1 site. By contrast, those that become pink due to irradiation and heating contain Mn3+ and Mn2+ at the M2 site. The emission band of the former is 625 nm, and for the latter, it is 591 nm.

Experimental and computational investigation of polymorphism in methyl 3-hydroxy-4-(piperidin-1-ylmethyl)-2-naphthoate

A piperidine substituted methyl 3-hydroxy-2-naphthoate was synthesized for application as a supramolecular host, which yielded colorless and light yellowish orange crystals using different solvents for crystallization. The crystals of the substituted methyl 3-hydroxy-2-naphthoate were analysed using melting point, IR, Reflectance UV–Visible, fluorescence, SEM, 1H NMR, DSC, PXRD and single crystal X-ray crystallographic techniques to reveal polymorphism. The crystal data were also analysed computationally using Gaussian 09, CLP-PIXEL, Crystal Explorer software to reveal the differences in the intermolecular interactions and optical properties. The short intermolecular interactions such as C–H … π and π … π interactions differentiated the polymorphs of the molecule studied here.

Feasibility of Cyclodextrin-Potassium Ion Assemblies Synthesis and Its Application in Loading Bio-active Molecules

In the study, colorless cubic crystals of “green” cyclodextrin (CD)-based assemblies were synthesized and their potential to load bio-active molecules such as drugs and, separately, enzymes were investigated. Busulfan (Bu), an anti-cancer drug widely used to treat chronic myelogenous leukemia (CML), was used as a test drug while trypsin and lipase were used as model enzymes. These porous CD-K+ ion assemblies were prepared by dissolving alkali metal salts and γ-CD in water followed by vapor diffusion in varying solvents for several days. Crystals were activated via dichloromethane dispersion and in vacuo drying. Slow vapor diffusion with ethanol was found to give the highest yield and fastest crystallization time among all the solvents used. The materials synthesized using ethanol were characterized to be cubic crystals with sizes ranging from 100–1000 µm that are stable up to 250 °C. Loading of Bu (%S) onto the CD-K+ ion assemblies and co-crystallization with trypsin (%N) were both successful, as confirmed by elemental analysis. Loading studies of Bu performed using thermogravimetric analysis (TGA) confirmed about 5 wt% loading in the porous materials.

P0132DIAGNOSIS OF HYPEROXALURIA FROM RENAL BIOPSY

Abstract Background and Aims Crystal-induced kidney disease refers to kidney injury caused by intratubular crystal deposition. The most common forms of crystalline nephropathy encountered in renal pathology are nephrocalcinosis and oxalate nephropathy. The purpose of our study is to determine the epidemiological and clinical characteristics of hyperoxaluria diagnosed from renal biopsy. Method We retrospectively reviewed all kidney biopsy specimens evaluated at renal pathology laboratory, from 1976 to 2019. The biopsy specimens were received from multiple medical department and medical centers. We studied 8900 biopsy specimens and we were focused on patients whose diagnosis of hyperoxaluria was made from renal biopsy Results We identified 25 cases (15 children and 10 adults) with a sex ratio H / F of 0.9. Mean age at diagnosis was 17.2 years old [4 months-73 years old]. Most patients were offspring of consanguineous mating (14 of 25) with intermarriage of first-degree cousins being the most common pattern. A family history of chronic kidney disease was found in 13 patients: indeterminated nephropathy (n = 6) and renal stone (n = 5) and primary hyperoxaluria (n=2). Among our patients, five had a history of urolithiasis. One patient had a history of chronic diarrhea related to Crohn's disease and one patient had a history of cephalic pancreatectomy and ileal resection. Initial symptoms and signs were dominated by renal failure (n = 25) with mean creatinine of 789.5 μmol / l [306-1832μmol / l], associated with proteinuria in 10 patients and hematuria in 11 patients. Arterial hypertension was present in 4 patients. Oligo anuria was reported in 4 patients without dilation of the urinary excretory pathways. In our patients, the diagnosis of crystalin nephropathy was revealed by renal biopsy. In one case, the diagnosis was made after renal transplant. In 4 cases the diagnosis was made by postmortem kidney biopsy. In all cases, the kidney biopsy specimen showed extensive intratubular crystal deposition and tubulointerstitial mononuclear cell infiltration with features of tubular injury and interstitial fibrosis. Examination of histologic slides showed colorless refractile crystals of polygonal appearance. Multicolored birefringence under polarized light identified these crystals as calcium oxalate. After different investigations (genetic and biological analysis), the diagnosis of hyperoxaluria was confirmed. Hyperoxaluria was primary in 23 patients and secondary in 2 patients. Conclusion Hyperoxaluria is a rare condition, often serious, involving renal prognosis and sometimes life-threatening, especially in early-onset forms. Early diagnosis and treatment should be done as soon as possible to slow the progression to end-stage renal failure. In patients with renal insufficiency, the diagnosis of hyperoxaluria is difficult. Renal biopsy can help when clinical and radiological data are not sufficient.

Crystallization and Purification of 4,4′‐Diaminodiphenyl Ether

AbstractThe purification of 4,4′‐diaminodiphenyl ether (ODA) was investigated. ODA, which contained impurities, was sublimated and anti‐solvent (ethanol)‐crystallized in N‐dimethylformamide (DMF). Fourier transform infrared (FTIR) results revealed that the sublimated crystal was basically identical with the pure ODA sample. The influence of different amounts of ethanol on particle size distribution was analyzed during anti‐solvent crystallization. The morphology of the ODA crystal was examined by scanning electron microscopy (SEM). The color of the sample enhanced from a brown powder to a colorless granular crystal. The purity of the sample could be increased from about 30 % to 87 %. With the operations of sublimation and anti‐solvent crystallization, the purity, crystal morphology, and particle size distribution of ODA were significantly improved.

SAT-460 HISTOLOGICAL DIAGNOSIS OF HYPEROXALURIA FROM RENAL BIOPSY

Crystal-induced kidney disease refers to kidney injury caused by intratubular crystal deposition. The most common forms of crystalline nephropathy encountered in renal pathology are nephrocalcinosis and oxalate nephropathy. The purpose of our study is to determine the epidemiological and clinical characteristics of hyperoxaluria diagnosed from renal biopsy. We retrospectively reviewed all kidney biopsy specimens evaluated at renal pathology laboratory, from 1976 to 2018. The biopsy specimens were received from multiple medical department and medical centers. We studied 8900 biopsy specimens and we were focused on patients whose diagnosis of hyperoxaluria was made from renal biopsy. We identified 25 cases (15 children and 10 adults) with a sex ratio H / F of 0.9. Mean age at diagnosis was 17.2 years old [4 months-73 years old]. Most patients were offspring of consanguineous mating (14 of 25) with intermarriage of first-degree cousins being the most common pattern. A family history of chronic kidney disease was found in 13 patients: indeterminated nephropathy (n = 6) and renal stone (n = 5) and primary hyperoxaluria (n=2). Among our patients, five had a history of urolithiasis. One patient had a history of chronic diarrhea related to Crohn's disease and one patient had a history of cephalic pancreatectomy and ileal resection. Initial symp­toms and signs were dominated by renal failure (n = 25) with mean creatinine of 789.5 μmol / l [306-1832μmol / l], associated with proteinuria in 10 patients and hematuria in 11 patients. Arterial hypertension was present in 4 patients. Oligo anuria was reported in 4 patients without dilation of the urinary excretory pathways. In our patients, the diagnosis of crystalin nephropathy was revealed by renal biopsy. In one case, the diagnosis was made after renal transplant. In 4 cases the diagnosis was made by postmortem kidney biopsy. In all cases, the kidney biopsy specimen showed extensive intratubular crystal deposition and tubulointerstitial mononuclear cell infiltration with features of tubular injury and interstitial fibrosis. Examination of histologic slides showed colorless refractile crystals of polygonal appearance. Multicolored birefringence under polarized light identified these crystals as calcium oxalate. After different investigations (genetic and biological analysis), the diagnosis of hyperoxaluria was confirmed. Hyperoxaluria was primary in 23 patients and secondary in 2 patients. Hyperoxaluria is a rare condition, often serious, involving renal prognosis and sometimes life-threatening, especially in early-onset forms. Early diagnosis and treatment should be done as soon as possible to slow the progression to end-stage renal failure. In patients with renal insufficiency, the diagnosis of hyperoxaluria is difficult. Renal biopsy can help when clinical and radiological data are not sufficient.

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.

Pharmacokinetics, tissue distribution, and safety evaluation of a ligustilide derivative (LIGc)

Ligustilide (LIG) is the main active ingredient of Angelica sinensis (Oliv.) Diels and has a neuroprotective effect against ischemic stroke. However, owing to its multi-conjugated unstable structure, the compound has poor drug-forming properties. Therefore, we synthesized highly stable colorless needle crystals (known as ligusticum cycloprolactam, LIGc) through the structural modification of LIG. After a stability experiment was conducted at room temperature for four months, no impurity peaks were found by HPLC-DAD analysis, which indicated that LIGc resolved the stability issues of LIG. LIGc was absorbed and eliminated rapidly after intravenous administration (Cmax = 6.42 ± 1.65 mg/L at a dose of 20 mg/kg) and oral administration (Tmax = 0.5 h, Cmax = 9.89 ± 1.62 mg/L at a dose of 90 mg/kg, t1/2z approximately 2.5 h). The absolute oral bioavailability (F) of LIGc was clearly higher than the F of LIG reported in the literature (F, 83.97 % versus 2.6 %). Linear dose-dependent pharmacokinetics were observed after oral administration, with a higher area under the curve (AUC0-t, 22.31 ± 2.88 mg/L*h) observed at 90 mg/kg than that at 45 mg/kg (AUC0-t, 13.673 ± 0.666 mg/L*h). Tissue distribution results indicated that LIGc easily crossed the blood-brain barrier (BBB) and was distributed widely to the main tissues and organs of rats. We also conducted a preliminary safety assessment of LIGc by means of an acute toxicity test in KM mice. All mice had excellent health status (ig, dosage of 5.0 g/kg), with no histopathological changes observed in the main organs.