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In the solid state, crystals of both 1-(7-chloro-1,4-dihydroquinolin-4-ylidene)thiosemicarbazide-methanol-water (2/1/1), 2C10H9ClN4S·CH3OH·H2O, (I), and its hydrochloride salt {systematic name: [(7-chloro-1,4-dihydroquinolin-4-ylidene)azaniumyl]thiourea chloride}, C10H10ClN4S+·Cl−, (II), assume the imine tautomeric form, contrary to other 4-amino-7-chloroquinolines. Of particular interest are the N-C bond lengths, which have appreciable double-bond character, and the C-N-C aromatic ring bond angle. Both of these parameters have been studied extensively in 4-amino-substituted quinolines. The crystal structures of (I) and (II) in this study provide interesting examples of the amino-imino tautomerism which exists in this class of compound and is, to the best of our knowledge, hitherto unreported. [ABSTRACT FROM AUTHOR]

A series of tetramethyl-(Cp′) and pentamethylcyclopentadienyl (Cp*) metal complexes (η 5 -C 5 Me 4 R)ZrCl 2 L CO (R = H( 1 ), Me( 2 )) and (η 5 -C 5 Me 4 R)HfCl 2 L CO (R = H( 3 ), Me( 4 )) where L CO is a bifunctional β -diketiminate ligand [2-(MeO)–C 6 H 4 )]NC(Me)CHC(Me)N[2-(MeO)–C 6 H 4 )] (L CO ) were prepared from corresponding tetramethyl- and (pentamethylcyclopentadienyl)metal trichlorides and the lithium precursor LiL CO . All complexes were characterized by their melting point, elemental analysis, 1 H and 13 C NMR spectroscopy, IR spectroscopy. In addition their solid-state structures were determined by X-ray diffraction techniques. In all cases, a pseudo-tetragonal pyramidal coordination environment of the metal centre with cyclopentadienyl ligand on the top and nearly isobidentately bonded nitrogen atoms of the chelating L CO ligand in an open η 5 -fashion was observed. The oxygen atoms positioned at the diketiminate periphery remained uncoordinated to transition metal in the solid phase as well as in solution. Besides the desired compounds, two hafnium complexes bearing either 2-methoxyaniline or 2-methoxyanilide ligands were isolated and structurally characterized as minor decomposition and dismutation products of 3 and 4 , respectively. Complexes containing the β -diketiminate ligand as well as its precursors were tested for catalytic activity in the polymerization of ethylene using different activators (MAO, MMAO and Al i Bu 3 /(Ph 3 C) + [B(C 6 F 5 ) 4 ] − ). Among the new complexes, the best activity as high as 340 kg PE (mol M hbar) −1 was achieved with 1 /Al i Bu 3 /(Ph 3 C) + [B(C 6 F 5 ) 4 ] − system. In attempts to clarify the activation process of group 4 metal-based precatalysts, the synthesis and NMR studies of the aluminium β -diketiminate complex Al( i Bu) 2 L CO were also carried out. [ABSTRACT FROM AUTHOR]

When copper(II) acetate is treated with the ionic liquid n-butylmethylimidazolium cyanide (BMIm-CN), in ethanol solution, two new copper coordination compounds are obtained. (BMIm)2[Cu4(CN)7] comprises a 3D coordination polymer of cyanide bridged copper ions. This anionic coordination polymer contains CuI as well as CuII ions, i.e. it is a mixed-valent compound. The polymer can be described as honeycomb structure with the BMIm+ cation being located in the cages. The second compound obtained from the chemical reaction is (BMIm)[Cu2(OAc)5][Cu(OAc)2(H2O)]2 ·C2H5OH, which can be described as double-salt. The first unit (BMIm)[Cu2(OAc)5] contains paddle wheel copper(II) acetato moieties, which are bridged by additional acetato ligands and form infinite chains. The second part of the double salt is the neutral, [Cu(OAc)2(H2O)]2 complex. These two parts as well as the co-crystallized ethanol molecule are connected through a network of hydrogen bridges. [ABSTRACT FROM AUTHOR]

Imidazo[1,5- a ]pyridines have been used as monodentate ligands in late transition-metal N -heterocyclic carbene (NHC) complexes, but the N -aryl substituted heterocyclic ligands also allow for the formation of C ∧ C* cyclometalated complexes, which has previously only been shown for iridium(III) complexes. Here we present the first C ∧ C* platinum(II) NHC complexes of this class. A monoanionic bidentate ligand L – acetylacetonato (acac) or dipivaloylmethanato (dpm) – was used to generate heteroleptic compounds of the general formula [(C ∧ C*-NHC)Pt(L)]. Seven mononuclear complexes and one binuclear complex are presented. The square-planar coordination of the C ∧ C* cyclometalated species was confirmed by spectroscopy and additionally by three solid-state structures. The complexes have been fully characterized including 195 Pt NMR and extensive 2D NMR studies (COSY, HSQC, HMBC, NOESY). From the experimental data we exclusively see the formation of five-membered metallacycles to the aryl substituent and no interaction with the pyridine part of the ligand, in good agreement with density functional theory calculations (B3LYP/6-31G(d)), which show that the five-membered metallacycles are significantly favoured over the four-membered metallacycles. [ABSTRACT FROM AUTHOR]

Calix[4]resorcinarenes form different types of structural conformations. When their methylene carbons are substituted by four phenyl groups, the molecule can adopt both chair and cone conformations depending on the reaction temperature. The solvent-free synthesis of 4,6,10,12,16,18,22,24-octahydroxy-2,8,14,20-tetraphenyl-resorcin[4]arene led to the formation of chair conformer (C2h) rather than the cone conformer forming a ternary inclusion complex upon crystallization from wet DMSO. The solid state structure of the ternary inclusion system was determined by single-crystal X-ray diffraction and proved that the host has adopted the chair conformation. The supramolecular interactions in the crystal structure of the solvated compound were carefully investigated. Studies on antimicrobial activities showed that the compound inhibited the growth of Gram-positive bacteria. [ABSTRACT FROM AUTHOR]

Solid-state structures of sym-dibenzo-16-crown-5 ( 1) and five derivatives with one or two substituents on the three-carbon bridge have been determined. The derivatives with three sp-hybridized carbons include sym-(propyl)dibenzo-16-crown-5 ( 4), sym-(pentafluorophenoxy)-dibenzo-16-crown-5 ( 5), and sym-[di(methoxymethyl)]dibenzo-16-crown-5 ( 6). Structures of two derivatives with sp-hybridization of the central carbon ( 7 and 8) were also determined. Twisting of the three-carbon bridge causes one of the terminal methylene groups to be oriented within the polyether cavity. [ABSTRACT FROM AUTHOR]

In this study, a hybrid synthetic gelatin-mono epoxy terminated polydimethylsiloxane polymer (PDMS-E grafted gelatin (PGG)) was successfully synthesized on a large scale. Supramolecular structure of gelatin, which was decided by the sophisticated inter- and intra-molecular interactions, significantly affected the self-assembly and phase behavior of PGG. Interestingly, the supramolecular organization of PGG could be tuned finely by negatively charged surfactants, such as sodium dodecyl sulfate (SDS) and sodium tetradecyl sulfonate (STSo), as revealed by high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), light microscopy (LM), and atomic force microscopy (AFM). SEM images exhibited the presence of spherical aggregates in PGG/SDS films while hexagonal array was observed in PGG/STSo films. The results of LM revealed that when PGG/STSo solution was dried, a successive structural transformation from spheres to hexagons, via sticks and butterfly-shaped aggregates as intermediates, was observed. However, the morphologies of the aggregates formed in PGG/SDS system did not exhibit any obvious change upon drying. Attenuated total reflection–Fourier transform infrared spectra combined with AFM observations indicated that the secondary structure and aggregation behavior of gelatin was modified with the change in the electrostatic and hydrophobic interactions, leading to the formation of diversified solid-state structures of PGG. [ABSTRACT FROM AUTHOR]

Ligands of type [R2C(OH)CH2](2-Me2NCH2C6H4)E [R = Me, E = S (1), Se (2), Te (3); R = Ph, E = S (4), Se (5)] were obtained in the reactions of (2-Me2NCH2C6H4)ELi and the corresponding R2C(OH)CH2Cl (R = Me, Ph) reagent. The reactions between the ligands 1-3 and 5 with AgOTf (OTf = OSO2CF3), in a 1:1 M ratio, resulted in the silver(I) complexes [AgOTf{E[CH2C(OH)R2](C6H4CH2NMe2-2)}] [R = Me, E = S (6), Se (7), Te (8); R = Ph, E = Se (9)]. The new compounds 1-9 were investigated by solution NMR spectroscopy (¹H, 19F, 77Se, 125Te, as appropriate). The ligands 1-5 were investigated also by 13C NMR. The IR spectra and the molar conductivity of the silver(I) complexes suggested a covalent nature of the Ag-OTf bond, while their ESI + MS spectra suggest the formation of dimeric species. Single crystal X-ray diffraction studies revealed a monomeric structure with intramolecular N⋯H-O hydrogen bonding for compound 5, while for the complex 6 dimeric associations formed by bridging ligands were found. [ABSTRACT FROM AUTHOR]

Differential scanning calorimetry (DSC) analysis for ethylene/propylene copolymers synthesized in the whole composition range with a supported metallocene catalyst has been carried out. The melting/crystallization process can be determined both in the ethylene and propylene rich regions covering a comonomer composition range of up to 20%. Two peaks are detected showing two different transitions ( Tm1 and Tm2). A procedure is developed for modeling DSC melting curves by using a model previously reported by Kissin. Two contributions are considered for the copolymer crystallization in connection with a random comonomer distribution. Such model favourably describes experimental DSC curves and Tm1 and Tm2 values. The obtained parameters follow a regular trend in accordance with its physical meaning. Standard deviation for melting temperatures reveals accurate calculated values. The analysis of the parameter trend allows a fit against composition and predicting melting temperatures, yielding also accurate values. [ABSTRACT FROM AUTHOR]

The structures ethanol solvated complexes of para-sulphonato-calix[4]arene with magnesium and calcium have been determined. Both show the classical bilayer structure of para-sulphonato-calix[4]arene. The cations are situated between the bilayers. In the case of the magnesium complex the cation is octahedrally coordinated by six water molecules, however for the calcium complex the cation is coordinated in two different geometries by water molecules, bridging oxygen atoms of the sulphonate anions and an oxygen of an ethanol molecule. Both complexes contain an ethanol molecule embedded in the macrocyclic cavity. [ABSTRACT FROM AUTHOR]

The ferromagnetic tetranuclear nickel(II) complex [Ni4(L)4(CH3OH)2]·2MeOH·8H2O (1) has been synthesized by reacting nickel nitrate hexahydrate with the Schiff base ligand H2L (H2L= N-(2-hydroxyphenyl)-3-methoxy-salicylideneamine). Complex 1 was characterized by analytical, thermogravimetric, optical and magnetic techniques. The solid state structure of 1 was established by single crystal X-ray diffraction analysis. Crystal structure determination shows the formation of a distorted Ni4O4 cubane moiety encapsulated by four Schiff base ligands. Compound 1 crystallizes in the triclinic space group with a =12.7624(9)Å, b =15.0477(9)Å, c =16.8589(10)Å, α =94.732(2)°, β =94.308(2)°, γ =99.136(2)° and Z =2. The magnetic properties of complex 1 show a predominant ferromagnetic coupling inside the Ni4 cluster with g =2.240, J 1 =+0.88cm−1, J 2 =+0.84cm−1, J 3 =−0.014cm−1, J 4 =+1.22cm−1 and D =9.6cm−1. [ABSTRACT FROM AUTHOR]

ABSTRACT The microstructure of neat conjugated polymers is crucial in determining the ultimate morphology and photovoltaic performance of polymer/fullerene blends, yet until recently, little work has focused on controlling the former. Here, we demonstrate that both the long-range order along the (100)-direction and the lamellar crystal thickness along the (001)-direction in neat poly(3-hexylthiophene) (P3HT) and poly[(3,3″-didecyl[2,2′:5′,2″-terthiophene]-5,5″-diyl)] (PTTT-10) thin films can be manipulated by varying crystallization temperature. Changes in crystalline domain size impact the yield and dynamics of photogenerated charge carriers. Time-resolved microwave conductivity measurements show that neat polymer films composed of larger crystalline domains have longer photoconductance lifetimes and charge carrier yield decreases with increasing crystallite size for P3HT. Our results suggest that the classical polymer science description of temperature-dependent crystallization of polymers from solution can be used to understand thin-film formation in neat conjugated polymers, and hence, should be considered when discussing the structural evolution of organic bulk heterojunctions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 700-707 [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbenes and their heavier homologues are, in part, stabilized by delocalization of the N lone pairs into the vacant p-orbital at carbon (or a heavier Group 14 element center). These interactions are usually absent in the corresponding P-substituted species, owing to the large barrier to planarization of phosphorus. However, judicious selection of the substituents at phosphorus has enabled the synthesis of a diphosphagermylene, [(Dipp)2P]2Ge, in which one of the P centers is planar (Dipp=2,6-diisopropylphenyl). The planar nature of this P center and the correspondingly short PGe distance suggest a significant degree of PGe multiple bond character that is due to delocalization of the phosphorus lone pair into the vacant p-orbital at germanium. DFT calculations support this proposition and NBO and AIM analyses are consistent with a GeP bond order greater than unity. [ABSTRACT FROM AUTHOR]

Cr3+-doped SrGa12O19 is demonstrated to be a broadband near-infrared (650-950 nm) long-persistent phosphor whose luminescence can last for more than 2 h after ultraviolet irradiation is stopped. Detailed analysis of the photoluminescence and thermoluminescence spectra and of the persistent decay behavior of the Cr3+-doped SrGa12O19 samples indicate that the persistent energy transfer from the SrGa12O19 host to the Cr3+ ions and the filling and release of electrons into and from the shallow and deep traps through the conduction band is responsible for the long-persistent phosphorescence. [ABSTRACT FROM AUTHOR]

Coordination study of 9-chloro-9-phosphaalkenylchloro-9-germafluorene fragment containing derivatives towards transition metals such as gold or palladium was carried out. The new complexes were fully characterized in solution by multinuclear NMR and in solid state by X-ray diffraction. [Display omitted] A comprehensive experimental/theoretical study was carried out on derivatives containing the 9-chloro-9-phosphaalkenylchloro-9-germafluorene fragment, in order to assess their stability upon coordination to transition metals such as gold or palladium. Complexes were fully characterized in solution by multinuclear NMR and in solid state by X-ray diffraction. An extensive study on the solid state molecular structures of the gold and palladium phosphaalkenyl germanium complexes is presented following different intermolecular associations. Density functional theory (DFT) calculations coupled with natural bond orbital (NBO) techniques were performed to shed further light on the structural features, the strength of intramolecular interaction and the bonding phenomena occurring within targeted molecules. [ABSTRACT FROM AUTHOR]

ABSTRACT p-n-Heptylphenylacetylene ( pHepPA) was stereoregularly polymerized in n-hexane at 25 °C using [Rh(nbd)Cl]2 catalyst (nbd: norbornadiene) and NEt3, affording the purple-red Poly( R) in 97% yield. A 80 °C heat treatment transformed Poly( R) to the black Poly( B). The Poly( R) X-ray diffraction (XRD) pattern revealed a hexagonal crystal structure comprising contracted cis-cisoid helices [ HexaPoly( R) CC]. The 80 °C heat treatment generated two tetragonal crystals: TetraPoly( B) CC containing contracted cis-cisoid helices and TetraPoly( B) CT containing stretched cis-transoid helices. The helical diameters before and after heat treatment were estimated using XRD and were consistent with molecular mechanics calculations (MMFF94 force field method). When heated at 80 °C in the solid phase, the λmax in the diffuse reflective UV-vis spectra of HexaPoly( R) CC shifted from 482 to 560 nm. Additionally, an endothermic transition occurred in the HexaPoly( R) CC differential scanning calorimetric trace at ∼80 °C. Therefore, these data corroborated the assertion that HexaPoly( R) CC thermally converted to TetraPoly( B) CC and TetraPoly( B) CT. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 5177-5183 [ABSTRACT FROM AUTHOR]

Pyrochlore structured Gd2Zr2O7 and Nd2Zr2O7 are produced via complex precipitation processing. A suite of characterization techniques, including FTIR, Raman, X-ray and electron diffraction, TEM, SEM as well as nitrogen sorption are employed to investigate the structural and grain size evolution of the synthesized and calcined powder. Results show that Gd2Zr2O7 with the pyrochlore structure are produced after calcination at 1400°C for 12h while Nd2Zr2O7 has already formed the pyrochlore structure at 1200°C. This method allows the formation of dense materials at relatively low temperature, with bulk densities over 92% of the theoretical values achieved after sintering at 1400°C for 50h. This unique aqueous synthetic method provides a simple pathway to produce pyrochlore lanthanide zirconate without using either organic solvent and/or mechanical milling procedures, making the synthesis protocol an attractive potential scale-up production of highly refractory ceramics. [ABSTRACT FROM AUTHOR]

ABSTRACT Poly(3-hexylthiophene) (P3HT) is a polymer widely used in organic photovoltaic devices. Discrepancies in information exist in the literature about its morphological structure in solution and in the solid state. This work is a theoretical study, in which the structure of P3HT in the solid state is deduced from its structure in solution and comparisons with optical absorption data. The results indicate that P3HT is not planar, either in solution or in the solid state. However, the effective conjugation length in the solid state is similar to that of a planar chain. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1350-1354 [ABSTRACT FROM AUTHOR]

ABSTRACT Positron annihilation lifetime spectroscopy (PALS) is a common technique used to characterize the porosity of polymers. Here, we expand its use to the study of ordered nanoporous polymer monoliths. Polystyrene (PS) monoliths with aligned cylindrical pores ranging in diameters from 15 to 35 nm were examined. Such large pores push the boundaries of the PALS technique. To achieve robust measurement, our system used larger detectors than those typically used for monolithic polymer samples. This was done to improve data rates while sacrificing timing resolution. Pore sizes determined using PALS were consistent with measurements made using small angle x-ray scattering. In addition, PALS was able to detect the collapse of the pores when the monolithic sample was heated above the Tg of PS. Because PALS measurements are not sensitive to the nature of the order within the structure nor are they, sensitive to the open or closed nature of the pores this technique could be expanded to a variety of other sample types. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1157-1161 [ABSTRACT FROM AUTHOR]

Abstract: In this paper a pyridine-based racemic ligand [N,N′-bis(2-pyridylmethylidene)-1,2-(R,R + S,S)-cyclohexanediamine], 1, and its new trifluoromethansulfonate (CF3SO3 −, triflate) and nitrate Eu(III) complexes were studied, both in the solid state and in acetonitrile (AN) solution. In the case of the triflate complexes, a combination of structural and spectroscopic evidences, revealed the different nature of the species in solution and in the solid state. On the contrary, the nitrate adduct in the solid state presented similar features as the complex present in AN solution. All triflate and nitrate complexes detected in solution are highly stable. [Copyright &y& Elsevier]

Abstract: Three one-dimensional silver(I) coordination polymers {[AgL1]NO3} n (1), {[AgL2]ClO4} n (2) and {[AgL2]NO3} n (2a), where L1 (pyridin-2-ylmethylene-(4-{[(pyridin-2-ylmethylene)-amino]-methyl}-benzyl)-amine) is a dicompartmental iminopyridine ligand derived from the Schiff-base condensation of α,α′-diamino-p-xylene and pyridine-2-carboxaldehyde and L2 (N-(4-((methyl(pyridin-2-ylmethyl)amino)methyl)benzyl)-N-methyl(pyridin-2-yl)methanamine) is the reduced N-methyl derivative of L1, have been isolated from the reaction of ligands with various silver salts. Six different conformations of L1 are known that give rise to different network structures for {[AgL1]ClO4} n . X-ray single crystal structure of polymer 1·5H2O reveals that the asymmetric unit contains five water molecules that form a two-dimensional hydrogen bonding network with nitrate counter anion. A new conformer of L1 is observed in the polymeric structure of 1·5H2O. Coordination polymers 2 and 2a, both made of [AgL2]+ repeating unit, contains different conformers of L2. As a result, different polymeric structures are obtained for 2 and 2a. The effect of counterion on the ligand conformation and subsequently on the polymeric structure is reported. [Copyright &y& Elsevier]

Abstract: Silver(I) ferrocenylcarboxylate [Fe(η 5-C5H4CO2Ag)(η 5-C5H5)] (1) subsequently decarboxylates either in boiling dichloromethane or tetrahydrofuran to give biferrocene [Fe(η 5-C5H4)(η 5-C5H5)]2 (2) and elemental silver. Phosphine silver(I) ferrocenylcarboxylates of type [Fe(η 5-C5H4CO2Ag(PR3)n)(η 5-C5H5)] (R = Ph: 4a, n = 1; 4b, n = 2; 4c, n = 3. R = n-Bu: 5a, n = 1; 5b, n = 2; 5c, n = 3. R = OMe: 6a, n = 1; 6b, n = 2; 6c, n = 3) are accessible by treatment of 1 with PR3 (3a, R = Ph; 3b, R = n-Bu; 3c, R = OMe) in the ratio of 1:n. With dppe (7) tetrametallic [Fe(η 5-C5H4CO2Ag(μ-dppe))(η 5-C5H5)]2 (8) (dppe = Ph2PCH2CH2PPh2) was formed. The structures of 4b and 8 in the solid state have been determined by single X-ray structure determination. In 4b the silver(I) ion possesses a pseudo-tetrahedral environment, whereby the four coordination sites are occupied by the chelated FcCO2 unit and two datively-bonded PPh3 ligands. Compound 8 forms in the solid state a dimer setup by a [Ag(μ-dppe)]2 central building block. The FcCO2 groups are chelated to Ag(I) thus resulting in a pseudo-tetrahedral coordination sphere at silver. The solution behavior of 4–6 was analyzed by temperature-dependent 31P{1H} NMR studies indicating ligand exchange processes. [Copyright &y& Elsevier]

The preparation, structures, and magnetic properties of a series of metal formate perovskites [CH3NH3][Mn xZn1− x(HCOO)3] were investigated. The isostructural solid solution can be prepared in the complete range of x=0-1. The metal-organic perovskite structures consist of an anionic NaCl type [Mn xZn1− x(HCOO)3−] framework with CH3NH3+ templates located in the nearly cubic cavities and forming hydrogen bonds to the framework. When the proportion of Mn increased (i.e., x changed from 0 to 1), the lattice dimensions and metal-oxygen and metal-metal distances show a slight, nonlinear increase because of the increased averaged metal ionic radius and the local structure distortion. Through the series, the magnetism changes from the long-range ordering of spin-canted antiferromagnetism for x≥0.40 to paramagnetism when x≤0.30, and the percolation limit was estimated to be xP=0.31(2) for this simple cubic lattice. In the low-temperature region, enhancement of magnetization and the gradual decrease and final disappearance of coercive field, remnant magnetization, and spin-flop field upon dilution were observed through this isotropic Heisenberg magnetic series. IR spectroscopic and thermal properties were also investigated. [ABSTRACT FROM AUTHOR]

A protected pentacene precursor is functionalized in the 6- and 13-positions with alkyne groups and subsequently derivatized by a copper-catalyzed azide-alkyne Huisgen cycloaddition (CuAAC) reaction. Aromatization then gives the desired pentacene derivatives. This method offers an expedient route to a range of bench-top stable, pentacene, and oligopentacene based chromophores, all derived from a single building block. These new pentacene derivatives are characterized by NMR, IR, and UV-Vis spectroscopies. X-ray crystallographic data for two derivatives is used to evaluate the prospect of electronic communication in the solid state via π-stacking interactions. [ABSTRACT FROM AUTHOR]

Cyclodextrins (CDs) are cyclic polysaccharides with nano-size, largely hydrophobic cavities, and exteriors covered with hydrophilic hydroxyl groups, making them water soluble. Threading and filling their cavities with polymer chains produces noncovalently bonded crystalline inclusion compounds (ICs). In this study, we formed fully covered, stoichiometric ICs between guest poly( L-lactic acid), poly(ε-caprolactone), and nylon-6 chains and host α-CD. Coalesced samples of all three polymers were obtained after appropriately removing the stacked α-CD host channels from their ICs. Distinct differential scanning calorimetriy (DSC) thermograms were observed for as-received and coalesced samples, with the coalesced samples crystallizing faster at higher temperatures from their melts, and this distinction was maintained even after extensive, long-time melt-annealing (hours, days, and weeks). We believe this is due to the largely unentangled chains with extended conformations that are more densely packed in the initially coalesced samples. When small amounts (∼2 wt %) of the coalesced polymers are used as self-nucleating agents for their as-received samples, the resulting self-nucleated samples show DSC thermograms similar to those of the neat coalesced polymers, including their long-time stability to melt-annealing. Coalesced polymers, whether neat or in samples they self-nucleate, may conserve their organization in the melt (largely extended and unentangled chains) for long periods, because the process of entangling the many chains influenced by a single initially extended unentangled coalesced chain, after it randomly coils, is extremely sluggish. By contrast, in melt-crystallized or solution-cast samples, polymer chains generally become fully randomly coiled, interpenetrate, and entangle after being heated and held in their melts for comparatively much shorter times. For example, we have recently observed (DSC) that ultra high molecular weight, gel-spun spectra polyethylene (PE) fibers® did not conserve or retain any memory of their as-spun and highly drawn semicrystalline morphology even after spending as little as 2 min in the melt. As a consequence of the comparison to the behavior of coalesced polymer melts, we believe that polyethylene chains in Spectra fibers® must be at least intimately dispersed within their crystalline regions, and likely partially coiled and entangled in their noncrystalline regions, thereby facilitating their rapid transformation into a full entanglement network of randomly coiling chains in the melt. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 [ABSTRACT FROM AUTHOR]

Abstract: A fundamental understanding of the nature and structure of the glass transition in amorphous materials is currently seen as a major unsolved problem in solid-state physics. A new conceptual approach to understanding the glass transition temperature (T g ) of glass-forming liquids called the twinkling fractal theory (TFT) has been proposed in order to solve this problem. The main idea underlying the TFT is the development of dynamic rigid percolating solid fractal structures near T g , which are said to be in dynamic equilibrium with the surrounding liquid. This idea is coupled with the concept of the Boltzmann population of excited vibrational states in the anharmonic intermolecular potential between atoms in the energy landscape. Solid and liquid clusters interchange or “twinkle” at a cluster size dependent frequency ω TF , which is controlled by the population of intermolecular oscillators in excited energy levels. The solid-to-liquid cluster transitions are in accord with the Orbach vibrational density of states for a particular fractal cluster g(ω)~ ω df−1, where the fracton dimension d f =4/3. To an observer, these clusters would appear to be “twinkling.” In this paper, experimental evidence supporting the TFT is presented. The twinkling fractal characteristics of amorphous, atactic polystyrene have been captured via atomic force microscopy (AFM). Successive two-dimensional height AFM images reveal that the percolated solid fractal clusters exist for longer time scales at lower temperatures and have lifetimes that are cluster size dependent. The computed fractal dimensions, ≈1.88, are shown to be in excellent agreement with the theory of the fractal nature of percolating clusters in accord with the TFT. The twinkling dynamics of polystyrene within its glass transition region are captured with time-lapse one-dimensional AFM phase images. The autocorrelation cluster relaxation function was found to behave as C(t) ~t − 4/3 and the cluster lifetimes τ versus width R were found to be in excellent agreement with the TFT via τ~ R 1.42. This paper provides compelling new experimental evidence for the twinkling fractal nature of the glass transition. [Copyright &y& Elsevier]

The structure and bonding of 7-silanorbornadienes was investigated using X-ray Diffraction (XRD), solid-state NMR spectroscopy and density functional calculations. The solid state structures of four benzo-7-silanorbornadienes ( 4a, c, d, e) and of one dibenzo-7-silabenzonorbornadiene ( 5a) are reported and compared with the results of previous structural investigations. The most prominent features of the molecular structures of all 7-silanorbornadienes are very long Si-C(bridgehead) bonds (d(SiC) = 190.6-196.8 pm) and very acute CSiC bond angles α (α(CSiC) = 78.7-83.9°). All newly investigated 7-silanorborndienes show for tetracoordinated silicon nuclei extremely deshielded Si NMR resonances (δSi = 65.6-31.6). Solid State NMR investigations for 7-silanorbornadienes anti- 4a, b reveal highly anisotropic chemical shift tensors of axial or nearly axial symmetry ( 4a: δ = 161, δ = δ = −11; 4b: δ = 113, δ = 14, δ = −15). The dominating, strongly deshielding δ component is oriented almost perpendicular to the plane spanned by the two bridgehead carbon atoms and the bridging silicon atom. The DFT calculations suggest that the origin of the strong deshielding is a small energy difference between the frontier orbitals, which are strongly localized at the silicon atom. In addition the computations reveal that both the long SiC bonds and the strongly deshielded Si NMR chemical shift are direct consequences of the bonding situation in 7-silanorbornadienes which are characterized by through space interaction of the C=C double bonds and by hyperconjugation between the SiC σ-bonds and the unoccupied orbitals of the C=C double bonds. [ABSTRACT FROM AUTHOR]

Abstract: Diketopyrrolopyrrole (DPP) derivatives with four different substituents were synthesized by cross-coupling reactions. The DPP derivatives were investigated in terms of their solid-state structure, absorption, emission, and electrochemistry. The electron-donating property of each substituent causes a redshift of UV/vis absorption and emission in the solution state. Although all of the DPP derivatives have high quantum yields in solution, only butoxyphenyl-substituted DPP exhibits strong emission in the solid state. [Copyright &y& Elsevier]

Abstract: The coordination geometry and supramolecular structures of three copper(II) complexes of two α-hydroxycarboxylates and one α-methoxycarboxylate with nitrogen donor co-ligands are discussed. The complexes have been characterized by elemental analysis, ESI-MS, IR and electronic spectroscopy, thermogravimetric analysis and magnetic measurements. The X-ray structure analysis of all the complexes, namely [(BPCA)CuII(MA)] (1), [(BPCA)CuII(MPA)(H2O)] (2) and [(BPCA)CuII(BA)]n (3), where BPCA=bis(2-pyridylcarbonyl)amidate, MA=racemic mandelate, MPA=racemic α-methoxy phenylacetate and BA=benzilate anion, shows the copper(II) ion in a distorted square-pyramidal geometry. In 1 the mandelate anion is coordinated to the copper(II) center in a bidentate fashion while in 2 the α-methoxycarboxylate is monodentate. In both cases a one-dimensional supramolecular array is formed through hydrogen bonds: the mononuclear units are directly connected in 1 by the MA hydroxyl group, whereas in 2 is the coordinated water that operates as H donor towards the MPA carboxylate group and the BPCA carbonyl oxygens of nearby complexes. In 3 the benzilate anion, acting as bridging ligand between copper ions, gives rise to a one-dimensional coordination polymer. In the latter, intra- and inter-chain π⋯π stacking interactions between pyridines and one phenyl ring of benzilate anions are observed in the packing. [Copyright &y& Elsevier]

The syntheses of two di(1,8-naphtho)-16-crown-4 compounds are described. In the X-ray structure of di(1,8-naphtho)-16-crown-4, the compound crystallizes in the orthorhombic space group Pna21 with four molecules per asymmetric unit. Alkali metal cation selectivities of the ionophores are assessed in solvent polymeric membrane electrodes. [ABSTRACT FROM AUTHOR]

Abstract: To overcome low oral bioavailability of poorly water-soluble drugs, self-emulsifying drug delivery systems (SEDDS) have been noted as a promising strategy. However, incorporation of drugs into SEDDS composed of Gelucire®44/14 could induce interactions not yet well understood. The aim of this study was to investigate the influence of drug polarity upon the solid-state structure of SEDDS formulation, particularly in terms of wettability, thermal behaviour and microscopic aspects and their effect upon the release properties of the SEDDS. Model drugs were naproxen and sodium naproxen (10% w/w), two drugs with similar chemical structure but different water solubilities. Both drugs had an effect on the structure and behaviour of SEDDS: sodium naproxen mainly increased surface wettability while naproxen modified its thermal behaviour. Moreover, influence of Gelucire®44/14 as self-emulsifying matrix was very marked for naproxen with a huge increase of naproxen release, the less water-soluble drug in condition where the solubility was the limiting parameter (at pH 1.2). Study of SEDDS structure and its physico-chemical properties using different techniques brought novel findings about the behaviour of SEDDS with different kinds of drugs (various water solubilities) and could be linked to their performances during in vitro dissolution. [Copyright &y& Elsevier]

Abstract: New π-conjugated pyrimidopyrimidine polymers with two different alkylamino groups at C4 and C8 positions, PPympym(4-NH-n-C8H17-8-NHR) (R= n-C4H9, n-C6H13, n-C12H25, and n-C16H33), were prepared by dehalogenation polycondensation using nickel zerovalent complex in high yield. The obtained polymers were partly soluble in organic solvents such as chloroform. A chloroform soluble part of PPympym(4-NH-n-C8H17-8-NH-n-C16H33) showed a number-average molecular weight of about 3,000 in GPC analysis. UV–vis spectra of the polymers in CHCl3 showed a π–π* absorption peak at about 450nm, and the peak position shifted by 30nm to a longer wavelength in film. The polymers showed photoluminescence both in solution and in film. Cast films of the polymers were electrochemically reduced at about −2.3V vs. Ag+/Ag. XRD patterns of the polymers revealed the polymers took an end-to-end packed structure. [Copyright &y& Elsevier]

When used as a precursor for carbene ligands, the complex's reactivity and potential catalytic activity can be increased by interaction with an electrode. Keywords: carbene ligands; electronic structure; ionic liquids; solid-state structure; thermal properties EN carbene ligands electronic structure ionic liquids solid-state structure thermal properties 1 1 1 04/08/22 20220406 NES 220406 B Task-specific b polyaryl-/oligoether-substituted, imidazolium-based ionic liquids (ILs) with linker moieties enable interaction with electrochemically active surfaces. Cover Feature: A New Class of Task-Specific Imidazolium Salts and Ionic Liquids and Their Corresponding Transition-Metal Complexes for Immobilization on Electrochemically Active Surfaces (Chem. Eur. J. 20/2022). [Extracted from the article]

Abstract: The reaction of 2-furfuraldehyde with orthosubstitued primary aromatic amine gives the furfuryl imine ligands (1–5) with high yields. A convenient synthesis is described. These compounds have been characterized by IR and NMR spectroscopies. The structure of the furfuryl imine (4), N-(2-furylmethylene)(2,6-dimethylphenylamine), was solved by X-ray diffraction. [Copyright &y& Elsevier]

Abstract: Cationic complexes [Mo(η3–C3H4–Me–2)(N–N)(CO)3]+PF6 −, {N–N=bipy (2); DAD (Ar–N013;C(Me)Ar: Ar=o-Me–C6H4 (3), 2,6-Me2–C6H3 (4); Ar–BIAN (Ar=o-Me–C6H4 (5), Ar=iPr2–C6H3 (6)}; were synthesized by treating the compound Mo(CO)3(p-xylene) with the allyloxyphosphonium salt in situ in presence of diimine ligand. Complex 4 was characterized by single crystal X-ray diffraction. The solid state structure of the complexes revealed a preference for the more unsymmetrical axial isomer. [Copyright &y& Elsevier]

Abstract: The preparation and solid-state structures of homoleptic Ru(II) complexes based on the ligands 4′-(4-carboxyphenyl)tpy (L1) (where tpy=2,2′:6′,2″-terpyridine) and 4′-(4-carboxyphenyl)-4,4″-di-(tert-butyl)tpy (L2) are described. Both complexes are found to possess polymeric solid-state structures due to hydrogen-bonding interactions. The first complex, [Ru(L1)2]2+, exhibits a more closely-packed structure relative to that of [Ru(L2)2]2+, which was found to have a porous solid-state structure due to the steric bulk of the tert-butyl groups. [Copyright &y& Elsevier]

Abstract: The hydrosulfido complexes CpRu(L)(L′)SH react with one equivalent of O-alkyl oxalyl chlorides (ROCOCOCl) to form the corresponding O-alkylthiooxalate complexes CpRu(L)(L′)SCOCO2R (L=L′=PPh3 (1), (2); L=PPh3, L′=CO (3); R=Me (a), Et (b)). The reactions of the hydrosulfido complexes with half equivalent of oxalyl chloride produce the bimetallic complexes [CpRu(L)(L′)SCO]2 (L=L′=PPh3 (4), (5); L=PPh3, L′=CO (6)). The crystal structures of CpRu(PPh3)2SCOCO2Me (1a) and CpRu(dppe)SCOCO2Et (2b) are reported. [Copyright &y& Elsevier]

Re(CO) 5 Br readily forms a complex with 2,2′-bibenzimidazole (bbimH 2 ) of the general composition (bbimH 2 )Re(CO) 3 Br, 1 . The complex was characterized by NMR, IR, electronic and emission spectroscopy. The orange-brown compound is sparingly soluble in apolar solvents but could be crystallized from a DMF/toluene mixture. An X-ray structural investigation shows that the rhenium ion has a distorted octahedral geometry. Nitrogen atoms of the bibenzimidazole are trans to two carbonyl ligands. The secondary amine protons of the bibenzimidazole ligand form a hydrogen bond to the amide oxygen of a DMF molecule; N3-O4 2.725(7) Å, N4-O4 2.761(7) Å. The bending angle of the two benzimidazole units is 168°; the greatest deviation from planarity within the ligand is 0.14 Å. Crystal data: monoclinic, space group P 2 1 / n , a = 10.9743(2), b = 12.9182(2), c = 15.1864(3) Å, β = 91.647(1)°, V = 2152.06(7) Å 3 , T = -90°C, Z = 4, R 1 = 0.025, wR 2 = 0.062 for 4296 reflections with F o > 4σ( F o ) out of 4886 independent reflections. [ABSTRACT FROM AUTHOR]

Series of samples of solid-phase chlorinated poly(ethylene) (CPE) have been studied by using both the methods of wide angle X-ray diffraction analysis (WAXD) and optical microscopy. Some basic crystallographic characteristics of CPE of 1.27 to 56.09 chlorine content were determined. The increase of chlorine content in the product was found to result in a relatively weak increase of the parameter a for melt-crystallized samples, whereas the parameter c values of the cold-sintered samples decreased. The crystallite sizes in the [110] and [020] directions for the melt-crystallized samples increased to the higher extent up to, approximately, 10% chlorine content, as compared to those of CPE available as powder or pellets. The degree of crystallinity was reduced as the chlorine content increased, but, even with 56% chlorine introduced, the polymer had a crystalline-amorphous structure. The optical micrographs showed that, up to 40% Cl, CPE had crystalline structure dominated by the formation of spherolites whereas, at higher chlorine content, structures of the lower order of crystallinity were formed. These observed changes were predominantly determined by the defects in the PE crystals, resulting from the inclusion of a certain fraction of chloromethylene groups therein. [Copyright &y& Elsevier]

When determining the degree of disorder of a lyophilized cake of a protein, it is important to use an appropriate analytical technique. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) are the most commonly used thermo-analytical techniques for characterizing freeze-dried protein formulations. Unfortunately, these methods are unable to detect solid-state disorder at levels < 10%. Also, interpretation of DSC results for freeze-dried protein formulations can be difficult, as a result of the more complex thermal events occurring with this technique. For example, proteins can inhibit the thermally induced recrystallization of the lyophilized cake, resulting in potential misinterpretation of DSC degree of disorder results. The aim of this investigation was to study the use of isothermal microcalorimetry (IMC) in the assessment of degree of solid-state disorder (amorphicity) of lyophilized formulations of proteins. For this purpose, two formulations of growth hormone were prepared by lyophilization. These formulations consisted of the same amounts of protein, mannitol, glycine, and phosphate buffer, but differed in the freeze-drying procedure. After lyophilization, the recrystallization of the samples was studied using IMC at 25°C under different relative humidities (58–75%). The effect of available surface area was studied by determining the heat of recrystallization (Q) of the samples before and after disintegration of the cakes. The results showed that, in contrast to DSC, IMC allowed detection of the recrystallization event in the formulations. Although both formulations were completely disordered and indistinguishable according to XRPD method, IMC revealed that formulation B had a different solid-sate structure than formulation A. This difference was the result of differences in the freeze-drying parameters, demonstrating the importance of choosing appropriate analytical methodology. [ABSTRACT FROM AUTHOR]

Na2[PtCl6] was found to react with (9-MeAH)Cl · H2O (2) (9-MeA=9-methyladenine) in aqueous solution yielding (9-MeAH)2[PtCl6] · 2H2O (3). The same compound was obtained from hexachloroplatinic acid and 9-methyladenine. Performing this reaction at 60 °C, complex formation took place yielding the 9-methyladeninium complex [PtCl5(9-MeAH)] · 2H2O (4a). An analogous complex, [PtCl5(9-MeAH)] · 1/2(18C6) · H2O (4b, 18C6=crown ether 18-crown-6), was formed in the reaction of aquapentachloroplatinic acid (H3O)[PtCl5(H2O)] · 2(18C6) · 6H2O (1) with 9-methyladenine in 1:1 ratio. All complexes were isolated in moderate to good yields as yellow powder (4b) and crystals (3, 4a), respectively. They were fully characterized by microanalysis, IR and NMR (1H, 13C, 195Pt) spectroscopies, and in part (2, 3, 4a) also by single-crystal X-ray diffraction analysis. Molecular structure of complex 4a exhibited that the 9-methyladeninium ligand is N1 protonated and coordinated through N7 to platinum(IV). [Copyright &y& Elsevier]

4-Me2NC6H4HgOH was prepared from 4-Me2NC6H4HgOAc. Full characterisation showed that it crystallises as discrete molecules, the first example of a true organomercury hydroxide in the solid state. The structures of 4-Me2NC6H4HgOAc and (4-Me2NC6H4)2Hg are also discussed. [Copyright &y& Elsevier]

Aliphatic–aromatic copolyesters of poly(butylene adipate-co-butylene terephthalate) [P(BA-co-BT)] with wide copolymer compositions were synthesized by melt polycondensation. Solution 13C NMR analyses show that the copolyesters are statistically random copolymers of BA and BT units. Their solid-state microstructures and thermal properties were investigated by wide-angle X-ray diffraction (WAXD), solid-state 13C NMR, differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The WAXD shows that the copolyesters with 10–25 mol% BT contain PBA crystals, while those with 27.5–80 mol% BT contain PBT crystals. In contrast, solid-state 13C NMR analyses demonstrate that the copolyesters with 20–30 mol% BT units contain both PBA and PBT crystals, but the minor one cannot be detected by X-ray diffraction due to the small sizes and amounts. Both the melting temperature and crystallinity of copolyesters show minimum values at around 25 mol% BT content which is the transition point from PBA crystal structure to PBT crystal structure. The composition dependences of melting temperature, crystallinity, crystallization rate and spherulite morphology are discussed and correlated to the biodegradability of the P(BA-co-BT) copolyesters. [Copyright &y& Elsevier]

Using several griseofulvin samples, representing different solid-state structures, the solubility behavior of drugs in both one-state (totally ordered, semiordered or disordered) and two-state systems was studied. Special attention was directed towards the surface structure of the particles. The partially crystalline samples were obtained by milling the raw material (crystalline standard) or storing the quenched sample (amorphous standard). The solid-state structure of the materials was studied using x-ray diffraction (XRD), differential scanning calorimetry (DSC), isothermal microcalorimetry (IMC), and scanning electron microscopy (SEM). The saturation concentration of the materials was studied in suspensions containing different dispersion concentrations of drug after centrifugation and filtration, using spectrophotometry. In all cases these dispersion concentrations exceeded the solubility of the drug. The solubilities were plotted vs. dispersion concentrations for each sample. Several solubility plateaus were found. The lowest and highest solubility plateaus corresponded to the solubilities of crystalline and amorphous standards. These plateaus were reached at 8 and 44 µg/mL for crystalline and amorphous griseofulvin standards, respectively. An intermediate plateau served as an indication of the existence of a totally semiordered structure. This was reached at 19 µg/mL for griseofulvin. Any deviation from these plateaus was suggested to be indicative of the existence of heterogeneity on the surface structure, which in most cases could be described as a two state system. In such cases, the apparent solubility was a function of dispersion concentration, until at very high dispersion concentrations (4000-20,000 µg/mL) the saturation concentration of the totally disordered (44 µg/mL) or semiordered (19 µg/mL) one-state phase was reached. No reduction in these values was observed during storage for 50 days. It is thus concluded that... [ABSTRACT FROM AUTHOR]

In the solid-state [Mo(NCS)(CO)2(η3-C3H5)(NCMe)2] · MeCN (1) contains a pseudo-octahedral arrangement of ligands about molybdenum, with carbonyls and nitriles in the equatorial plane and an N-bonded thiocyanate group trans to the allyl ligand. In refluxing methanol or acetonitrile both 1, and the analogous chloro-complex [MoCl(CO)2(η3-C3H5)(NCMe)2] (2) catalytically convert PhC&z.tbnd6;CPh to a mixture of hexaphenylbenzene and E,E-1,2,3,4-tetraphenylbutadiene. By contrast MeO2CC&z.tbnd6;CCO2Me is not oligomerised. In methanol, complex 2 dimerises 1,4-diphenylbutadiyne to Z,E-1,4,5,8-tetraphenyl-1,7-octa-3,5-diene-1,7-diyne, whereas in the presence of base both the complex and the diyne, react preferentially with the solvent to generate the [Mo2(CO)4(η3-C3H5)2(OMe)3]− anion and Z-1,4-diphenyl-3-methoxy-but-3-ene-1-yne, respectively. [Copyright &y& Elsevier]

Based on the bis(alkinyl) titanocene [Ti](C&z.tbnd6;CSiMe3)2 (1) a series of mixed early–late metal complexes of the general type {[Ti](C&z.tbnd6;CSiMe3)2}ML {[Ti]=(η5-C5H4SiMe3)2Ti; M=Ni, Pd; L=PPh3, P(OMe)3, P(OPh)3} was prepared. The solid-state structure of {[Ti](C&z.tbnd6;CSiMe3)2}Pd(PPh3) (2) is reported. Complex 2 exhibits typical features of early–late heterobimetallic tweezer complexes: (i) a pseudo-tetrahedrally coordinated Ti(IV) centre; (ii) a trigonal-planar coordination sphere around the Pd(0) centre, comprised of the two η2-coordinated Me3SiC&z.tbnd6;C entities and the datively-bound PPh3 ligand; (iii) a lengthening of the C&z.tbnd6;C triple bonds upon their η2-coordination to Pd(0); and (iv) a trans-deformation of the Ti&z.sbnd;C&z.tbnd6;C&z.sbnd;SiMe3 units due to the tweezer effect. Cyclic voltammetric studies on 2 and {[Ti](C&z.tbnd6;CSiMe3)2}NiL [3, L=CO; 4a, L=P(OCH3)3] reveal an electron donating character of the coordinated M(0) centres, which is demonstrated by the shift of the Ti(IV)/Ti(III) reduction to a more negative potential. This reductive process also exhibits a dependence on the π-acidity of the respective Lewis-base L. [Copyright &y& Elsevier]

Chiral trans-anti-trans-dicyclohexano-18-crown-6 isomers are synthesized via a lipase-catalyzed reaction. The solid-state structure of the (S)-enantiomer is determined and compared with those reported for 18-crown-6 and trans-syn-trans-dicyclohexano-18-crown-6. [Copyright &y& Elsevier]

The cluster [HIr5(CO)12]2- (1) was prepared by condensation of [HIr4(CO)11]- and [Ir(CO)4]- (molar ratio 1:1) in refluxing THF, with almost quantitative yields. Its solid state structure was determined by X-ray diffraction at low temperature on the salt [PPh3CH2Ph]2[HIr5(CO)12]. The metal atoms define a trigonal bipyramidal arrangement. The hydride ligand was located indirectly as a bridge between apical and equatorial metal atoms. The phosphine-substituted cluster [HIr4(CO)10PPh3]- (2) was synthetized by CO displacement on [HIr4(CO)11]-, in THF at room temperature. This reaction is selective, with no traces of polysubstitution products. In the solid state, the hydride and the triphenylphosphine are axially bound on basal iridium atoms; the terminal hydrogen atom was directly located by X-ray analysis at a Ir–H distance of 1.57(9) Å. On the contrary, two isomers are present in THF solution, and they interconvert rapidly at room temperature, as shown by1H and 31P NMR spectra. [ABSTRACT FROM AUTHOR]