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para-Aminobenzoic acid (p-ABA) is a pharmaceutical compound with a challenging polymorph nucleation behavior. It has 4 polymorphs and multiple solvates. Among these forms, the α and the β form are subjects of interest for research in many studies. The α form nucleates predominantly in many solvents. The β form is known to nucleate in only 2 solvents. The reasoning for this was that the solvents, having a strong interaction with the COOH group, inhibit the dimerization of the COOH group leading to the nucleation of the β form. Following this reasoning, in this work, DMSO and DMF, which have strong interaction with the COOH group, were tested as solvents for anti-solvent crystallization experiments. Water was used as anti-solvent. The goal was to investigate the resultant polymorph nucleation under such specific solvent–solute interaction. Results showed that with DMSO as solvent at higher anti-solvent volume fraction the α form nucleated predominantly. At lower volume fractions there was no nucleation normally but addition of some seeds quickly led to β form nucleation. With DMF, a special result was seen where a new solvate between p-ABA and DMF was discovered. Single crystal XRD results confirmed that the formation of the solvate was a result of hydrogen bonding between the solute and the solvent. Overall, the results do confirm that solvents having strong interaction with the COOH group can lead to nucleation of forms other than the persistent form. [ABSTRACT FROM AUTHOR]

An easily accessible experimental set-up to grow large single crystals of two sweeteners readily available in supermarkets, erythritol and xylitol, is described. The crystallization of these compounds illustrates the principles of crystallization by evaporation. As these artificial sweeteners are also known to induce a cool sensation in the mouth, the crystal-growing experiment is complemented with a simple calorimetric set-up to demonstrate the endothermic nature of the dissolution of the selected sweeteners in a more quantitative approach by measuring the heat of dissolution (ΔHdiss). The choice of these two sweeteners also allows use of the freely available WebCSD and Mercury tools to visualize their three-dimensional structure, crystal packing and powder diffractograms, and to deepen stereochemical concepts such as stereoisomers and meso compounds. [ABSTRACT FROM AUTHOR]

Two new Ag(I) complexes with 1,3-bis(imidazol-1-ylmethyl)benzene (L1) and 1,3-bis(imidazol-1-ylmethyl)-5-methylbenzene (L2), namely {[AgL1]CF3SO3}n (1) and {[AgL2]CF3SO3}n (2), were synthesised and characterised by SCXRD to uncover the effect that introducing a methyl group to the benzene core of the ligand has on the molecular/crystal structure of the metal complex. The studies revealed a high level of isostructurality of the formed Ag(I) complexes, consisting of 1D cationic chains with the charge neutralised by the counterions applied. These results triggered structural investigations of the parent ligands, which, as revealed by SCXRD, crystallise as dihydrates in different space groups of a monoclinic system. Further analyses revealed that the motifs in their molecular packing in general stay the same. However, some morphotropic/positional adjustments are taking place in L2 to accommodate the presence of the methyl substituent. [ABSTRACT FROM AUTHOR]

Interaction of [Pt(µ -Cl)(arylolefin)] 2 with either quinoline (Q) or four derivatives (N , O H) afforded 2 – 10. The N atom of Q and (N , O) are at the cis position with respect to the allyl group in all the complexes. The cytotoxicity of 4 against Lu and 5 against KB cell lines are approximately 6 and 4 times lower than cisplatin, respectively. [Display omitted] Nine new cyclometalated platinum(II) complexes of the formula [PtCl(arylolefin)(Q)] (2 , 3) and [Pt(arylolefin)(N , O)] (4 – 10) (arylolefinH: eugenoxyacetic acid, isopropyl eugenoxyacetate; Q: quinoline; (N , O H): quinolin-8-ol, 2-methylquinolin-8-ol, 5,7-dichloroquinloin-8-ol and quinoline-2-carboxylic acid] were synthesized and fully characterized by EA, ESI mass spectrometry, IR and NMR spectroscopy and single-crystal X-ray diffraction for 3 , 7 and 10. The results show that the arylolefin binds with PtII via the C5 atom of the phenyl ring and the C C allyl in all the synthesized complexes. Quinoline coordinates with PtII via its N atom in 2 , 3 , while deprotonated (N , O H) coordinates with PtII via both the N and O atoms in 4 – 10. The N atom of Q and (N , O) in all complexes are at the cis position with respect to the allyl group of the arylolefin. The XRD confirms the square-planar coordination of PtII and trans position of the arylolefin and quinoline ligands. The results of in vitro cytotoxicity tests against human cancer cell lines KB and Lu of 2, 4 – 8 indicate that 4 and 5 exhibit the highest activities against Lu and KB cell lines with the IC 50 values of 7.1 and 4.1 µM, respectively, which are approximately 6 and 4 times lower than cisplatin. [ABSTRACT FROM AUTHOR]

The effect of a range of solvents on non-porous single crystals of a cyclic, dinuclear silver(i) complex with 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (bitmb) with the formula [Ag2(bitmb)2](BF4)2 (1) was investigated by single crystal X-ray diffraction studies. It allowed us to get a few snapshots of the process of solvent diffusion through the crystal, connected with a series of reversible transformations. We have isolated disolvated 2a and monosolvated 2b forms with acetonitrile, monosolvated 3b and 4b forms with acetone and ethanol, respectively, and monosolvated 4c form with ethanol which is an intermediate between 1 and 4b. Longer exposure of the crystals to solvent vapours leads to the formation of a polymeric 1D Ag(i) complex with the general formula [Agbitmb(BF4)]n (5). [ABSTRACT FROM AUTHOR]

Motivation: With the rapid increase of the structural data of biomolecular complexes, novel structural analysis methods have to be devised with high-throughput capacity to handle immense data input and to construct massive networks at the minimal computational cost. Moreover, novel methods should be capable of handling a broad range of molecular structural sizes and chemical natures, cognisant of the conformational and electrostatic bases of molecular recognition, and sufficiently accurate to enable contextually relevant biological inferences. Results: A novel molecular topology comparison method was developed and tested. The method was tested for both ligand and binding pocket similarity analyses and a PDB-wide ligand topological similarity map was computed. Conclusion: The unprecedentedly wide scope of ligand definition and large-scale topological similarity mapping can provide very robust tools, of performance unmatched by the present alignment-based methods. The method remarkably shows potential for application for scaffold hopping purposes. It also opens new frontiers in the areas of ligand-mediated protein connectivity, ligand-based molecular phylogeny, target fishing, and off-target predictions. [ABSTRACT FROM AUTHOR]

Motivation: With the rapid increase of the structural data of biomolecular complexes, novel structural analysis methods have to be devised with high-throughput capacity to handle immense data input and to construct massive networks at the minimal computational cost. Moreover, novel methods should be capable of handling a broad range of molecular structural sizes and chemical natures, cognisant of the conformational and electrostatic bases of molecular recognition, and sufficiently accurate to enable contextually relevant biological inferences. Results: A novel molecular topology comparison method was developed and tested. The method was tested for both ligand and binding pocket similarity analyses and a PDB-wide ligand topological similarity map was computed. Conclusion: The unprecedentedly wide scope of ligand definition and large-scale topological similarity mapping can provide very robust tools, of performance unmatched by the present alignment-based methods. The method remarkably shows potential for application for scaffold hopping purposes. It also opens new frontiers in the areas of ligand-mediated protein connectivity, ligand-based molecular phylogeny, target fishing, and off-target predictions. [ABSTRACT FROM AUTHOR]

Sulfur(VI)‐fluoride exchange (SuFEx) chemistry, an all‐encompassing term for substitution events that replace fluoride at an electrophilic sulfur(VI), enables the rapid and flexible assembly of linkages around a SVI core. Although a myriad of nucleophiles and applications works very well with the SuFEx concept, the electrophile design has remained largely SO2‐based. Here, we introduce S≡N‐based fluorosulfur(VI) reagents to the realm of SuFEx chemistry. Thiazyl trifluoride (NSF3) gas is shown to serve as an excellent parent compound and SuFEx hub to efficiently synthesize mono‐ and disubstituted fluorothiazynes in an ex situ generation workflow. Gaseous NSF3 was evolved from commercial reagents in a nearly quantitative fashion at ambient conditions. Moreover, the mono‐substituted thiazynes could be extended further as SuFEx handles and be engaged in the synthesis of unsymmetrically disubstituted thiazynes. These results provide valuable insights into the versatility of these understudied sulfur functionalities paving the way for future applications. [ABSTRACT FROM AUTHOR]

Sulfur(VI)‐fluoride exchange (SuFEx) chemistry, an all‐encompassing term for substitution events that replace fluoride at an electrophilic sulfur(VI), enables the rapid and flexible assembly of linkages around a SVI core. Although a myriad of nucleophiles and applications works very well with the SuFEx concept, the electrophile design has remained largely SO2‐based. Here, we introduce S≡N‐based fluorosulfur(VI) reagents to the realm of SuFEx chemistry. Thiazyl trifluoride (NSF3) gas is shown to serve as an excellent parent compound and SuFEx hub to efficiently synthesize mono‐ and disubstituted fluorothiazynes in an ex situ generation workflow. Gaseous NSF3 was evolved from commercial reagents in a nearly quantitative fashion at ambient conditions. Moreover, the mono‐substituted thiazynes could be extended further as SuFEx handles and be engaged in the synthesis of unsymmetrically disubstituted thiazynes. These results provide valuable insights into the versatility of these understudied sulfur functionalities paving the way for future applications. [ABSTRACT FROM AUTHOR]

The Nenitzescu reaction is a condensation reaction between an enamine and a quinone, which can give rise to a wide variety of reaction products depending on the nature of the starting material and the reaction conditions. The most commonly observed products are 5-hydroxyindoles and 5-hydroxybenzofurans. Both classes are of interest since they are known to possess a variety of promising bioactivities. Despite the high chemodivergency for this reaction, it remains an interesting synthetic strategy thanks to the mild reaction conditions, easily accessible starting materials and simple reaction procedures. For these reasons, our research group investigated the Nenitzescu reaction of piperazinone enaminoesters, resulting in the unexpected formation of rearranged 2-imidazolidinone benzofurans. In this work, we aimed to develop reaction conditions that favor the formation of 5-hydroxyindoles via an extensive, multivariate optimization study. This led to valuable insights into the parameters that influence regio- and chemoselectivity. Furthermore, two novel products were obtained, a pyrrolo[2,3-f]indole and a benzofuranone, both of which are rarely reported in the literature. [ABSTRACT FROM AUTHOR]

The title compound, C10H14BrN5O2S, is the bromobenzenesulfonamide derivative of the type 2 diabetes drug metformin. The asymmetric unit contains two molecules with almost identical conformations but a different orientation of the bromophenyl moiety. Both molecules exhibit intramolecular N--H· · ·N and N--H· · ·O hydrogen bonds. The molecular packing features chain formation in the a-axis direction by alternating N--H· · ·N and N--H· · ·O interactions. In addition, ring motifs consisting of four molecules and π-π interactions between the phenyl rings contribute to the three-dimensional architecture. A Hirshfeld surface analysis shows that the largest contributions to surface contacts arise from contacts in which H atoms are involved. [ABSTRACT FROM AUTHOR]

rsCherryRev1.4 has been reported as one of the reversibly photoswitchable variants of mCherry, and is an improved version with a faster off‐switching speed and lower switching fatigue at high light intensities than its precursor rsCherryRev. However, rsCherryRev1.4 still has some limitations such as a tendency to dimerize as well as complex photophysical properties. Here, the crystal structure of rsCherryRev1.4 was determined at a resolution of 2 Å and it was discovered that it forms a dimer that shows disulfide bonding between the protomers. Mutagenesis, gel electrophoresis and size‐exclusion chromatography strongly implicate Cys24 in this process. Replacing Cys24 in rsCherryRev1.4 resulted in a much lower tendency towards dimerization, while introducing Cys24 into mCherry correspondingly increased its dimerization. In principle, this finding opens the possibility of developing redox sensors based on controlled dimerization via disulfide cross‐linking in fluorescent proteins, even though the actual application of engineering such sensors still requires additional research. [ABSTRACT FROM AUTHOR]

Analyzes the conformational flexibility manifested by DNA with the occurrence of unrestrained SHELXL refinement. Correlation of high-data to parameter-ratio with the conformational mobility of DNA; Conformations adopted by phosphates which were not rigidified by intercalations.

Methyl 4-(1,3a,6a-triazapentalen-3-yl)benzoate (TAP1) shows interesting properties as a small molecule fluorophore. In the search for post-functionalization methods, palladium-catalyzed arylation reactions were demonstrated. Direct CH arylation reactions of TAP1 with various aryl halides resulted in 3,6-diaryltriazapentalenes TAP4, although mostly in poor yields. Bromination of TAP1 followed by Suzuki coupling, on the other hand, requires a more delicate procedure, but gave arylated products with the same regiochemistry (TAP4) in moderate to good yields. The structure of 6-phenyltriazapentalene TAP4a was confirmed by crystallographic analysis. In addition, the effect of the C6 arylation on the fluorescent properties of 3-aryl-1,3a,6a-triazapentalenes was studied in dichloromethane at room temperature and in 2-methyltetrahydrofuran at 77 K, while the photophysical properties of two saponified derivatives were measured in acetonitrile. [ABSTRACT FROM AUTHOR]

Describes the x-ray crystal structure of the oligonucleotide d(GGCCAATTGG). Design of this structure to contain the d(G...GC)2 fragment, thus providing the basic repeat unit of a DNA triple helix; Significance of nucleic acid triplexes to genome analysis and antigene therapy.

The Lewis acid mediated Nenitzescu reaction with piperazinone enaminoesters surprisingly afforded rearranged 2-imidazolidinone 5-hydroxybenzofurans. The reaction was optimised and a scope study was performed. A one-pot two-step procedure was realised starting directly from 1,2-diaminoethane, diethyl acetylene dicarboxylate and 1,4-benzoquinone. A plausible reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

Disubstituted isothiazolo[4,3-b]pyridines are known inhibitors of cyclin G-associated kinase. Since 3-substituted-7-aryl-isothiazolo[4,3-b]pyridines remain elusive, a strategy was established to prepare this chemotype, starting from 2,4-dichloro-3-nitropyridine. Selective C-4 arylation using ligand-free Suzuki-Miyaura coupling and palladium-catalyzed aminocarbonylation functioned as key steps in the synthesis. The 3-N-morpholinyl-7-(3,4-dimethoxyphenyl)-isothiazolo[4,3-b]pyridine was completely devoid of GAK affinity, in contrast to its 3,5- and 3,6-disubstituted congeners. Molecular modeling was applied to rationalize its inactivity as a GAK ligand. [ABSTRACT FROM AUTHOR]

The title compound, C27H20N4O3S, crystallizes in the monoclinic system, space group P21/n, with Z = 4. The global shape of the molecule is determined by the orientation of the substituents on the central 4H-1,2,4-triazole ring. The nitrophenyl ring, phenyl ring, and naphthalene ring system are oriented at dihedral angles of 82.95 (17), 77.14 (18) and 89.46 (15)°, respectively, with respect to the triazole ring. The crystal packing features chain formation in the b-axis direction by S...O interactions. A Hirshfeld surface analysis indicates that the highest contributions to surface contacts arise from contacts in which H atoms are involved. [ABSTRACT FROM AUTHOR]

Reports on the X-ray analysis of the structure of a DNA nonamer. Extended crystal structure containing (C.G)*G triplets; Association of triplex formation with partial opening of the Watson and Crick pair; Heavily hydrated oligonucleotides; Information on recognition features of molecules.

We report, herein, a palladium‐catalyzed cascade comprising carbopalladation, migratory insertion of isocyanide and triple bond activation followed by a nucleophilic attack (OR−) to construct difunctionalized acyl indoles. The process involves multiple bond formations via key palladium‐chemistry steps, to construct these bis‐heterocycles containing two privileged scaffolds (indole and oxindole) in a single operational step, along with attempts to generate enantioselectivity at a quaternary carbon center. The methodology also demonstrates a continuous‐flow process to synthesize aryl isocyanides within minutes and using them in a telescopic manner. [ABSTRACT FROM AUTHOR]

A new family of unsymmetrical boron chromophores chelated with two BF2 units, named BOPAM, has been developed via a one‐pot, three‐step reaction starting from commercially available thioamides via i) conversion to amidrazones, ii) condensation with pyrrole aldehydes, and iii) boron chelation. This synthetic pathway has been proven to be highly efficient, having a broad substrate tolerance and giving the BOPAM products high yield. Notably, some of the BOPAM dyes show interesting photophysical properties with fluorescence quantum yields up to 0.98 in toluene. A fine‐tuning of their emissive properties has been attained through tailored molecular design strategies guided by in‐depth computational investigations. Tailored substitution with electron‐donating groups at the BOPAM ring leads to the opening of a non‐radiative decay channel involving a dark state and consequently a significant quenching of the fluorescence. The study is complemented by exhaustive steady‐state and time‐resolved spectroscopic measurements. [ABSTRACT FROM AUTHOR]

The molecular and crystal structure of (E)-2-[(benzo[d]thiazol-2-ylimino)- methyl]-5-(diethylamino)phenol (C18H19N3O2S, Et2N-Bz) and its unexpected reaction product with triphenylborane, 2,2-diphenyl-1,3-dioxa-2-borata-1,2-dihydronaphthalene [systematic name: N,N-diethyl-2,2-diphenyl-2H-1,3λ³,2λ4-benzodioxaborinin-7-amine, C23H24BNO2, (I)] are described. For Et2N-Bz, the hydroxyl group is involved in an intramolecular hydrogen bond with the imino nitrogen atom and the C N bond displays an E configuration. The crystal packing is characterized by layers of inversion dimers parallel to the (101) plane and chains of molecule in the a-axis direction formed through C--H⋯O interactions. Complex (I) crystallizes with two molecules (A and B) in the asymmetric unit, which differ in the orientation of the ethyl groups. The 1,3- dioxa-2-borata-1,2,3,4-tetrahydronaphthalene ring displays a slight envelope conformation with the boron atom as the flap. In the crystal packing, chains of alternating A and B molecules formed by C--H⋯O hydrogen bonds run in the b-axis direction. The UV--vis absorption and emission properties of the compounds are discussed and their aggregation-induced emission properties are further investigated. [ABSTRACT FROM AUTHOR]

This study presents a synthesis of 4 H-[1,2,3]triazolo[1,5- a]indol-4-ones. The key step in the synthesis of this new heterocyclic scaffold is an intramolecular cyclization via an unprecedented carbonylative C-H functionalization of 1-(2-bromoaryl)-1,2,3-triazoles. Isotopic labelling of the carbonyl carbon atom is possible using near stoichiometric amounts of 13CO. Additionally, an alternative pathway via carbonylative Sonogashira coupling followed by a two-step, one-pot azidation/cycloaddition is also investigated, giving rise to the same scaffold. [ABSTRACT FROM AUTHOR]

Manganese(ii)-containing ionic liquids were synthesized, in which the manganese atoms are coordinated by glymes (diglyme, triglyme, tetraglyme), pyridine-N-oxide, dimethylsulfoxide or N-alkylimidazoles (N-methylimidazole, N-butylimidazole and N-hexylimidazole). As anion, bis(trifluoromethanesulfonyl)imide (bistriflimide, Tf2N−), trifluoromethanesulfonate (triflate, OTf−) or methanesulfonate (mesylate, OMs−) were used. The compounds were characterized by CHN analysis, FTIR, DSC and single-crystal X-ray diffraction measurements. All manganese atoms were six-coordinate. It was found that the glyme-type ligands were replaced by atmospheric water upon leaving the crystals open to the air for several days. The crystal structures of seven compounds were described in detail and the compounds with the lowest melting temperatures were tested as electrolytes for the electrodeposition of manganese (thin) films. An irreversible reduction wave from Mn(ii) to Mn(0) and granular manganese deposits were observed for all compounds, except for liquid manganese salts with N-alkylimidazole ligands and bistriflimide anions, where the electrochemical formation of manganese nanoparticles was observed instead of the deposition of a manganese layer. However, for compounds with the same cation but with a triflate or methanesulfonate anion, manganese metal deposits were obtained, indicating that the nature of the anion has an important effect on the electrochemical properties of liquid metal salts. [ABSTRACT FROM AUTHOR]

In this work, a novel compound N-(3-(4-methoxyphenyl)isoxazolin-5-yl)methylsaccharin has been synthesized. The molecular structure of the compound was determined using various spectroscopic techniques and confirmed by a single-crystal X-ray diffraction analysis. In the single crystal, C–H...O hydrogen bonds between neighboring molecules form chains along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (35.7%), H...O/O...H (33.7%), and H...C/C...H (13%) interactions. The optimized structure calculated using density functional theory at the B3LYP/6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap is 4.9266 eV. [ABSTRACT FROM AUTHOR]

Eight polythiophene derivatives containing pyrazoline side groups were synthesized by a chemical oxidative coupling polymerization using FeCl3. The crystal structures of four monomers were determined which confirm the almost perpendicular orientation of the thiophene and pyrazoline rings, while the other substituents are more coplanar. Analyses of IR, 1H-NMR, Raman and UV-Vis spectra demonstrated that the suggested polymerization was successful to generate the synthesized polythiophenes with the expected structures. The morphology of the synthesized polythiophenes was studied by SEM. The different substituents attached to the 1- and 3-positions of the pyrazoline side chain led to differences in optical properties, electrical conductivity, and thermal stability of the synthesized polythiophenes. By adding a pyrazoline side chain to polythiophenes, some polymers achieve good solubility, electrical conductivity of about 1.3 × 10–6 S/cm, high fluorescence intensity (above 40,000 a.u.) at 505–550 nm and thermal stability up to 590°C in the air. [ABSTRACT FROM AUTHOR]

The reaction of complexes [Pt(μ‐Cl)(arylolefin)]2 with various either weak σ‐donor LN,S,O ligands or strong σ‐donor NHCs ligands results in [PtCl(arylolefin)(LN,S,O)] with LN,S,O in a cis position to the C=C group (series A) or [PtCl(arylolefin)(NHC)] with NHC in a trans position to the C=C group (series B), respectively. The reaction directions are decided by the nature of the reactants, and not by the reaction conditions. Analyses of NMR spectra, XRD and DFT results indicate that the formation of series B is strongly dominated by electronic properties, while steric factors direct the reaction to form series A. The chemical shifts of ethylenic protons and carbons as well as the values of 2JPtH, 3JPtH for the allyl protons and the 3JPtH value for H6 in the aryl group are unambiguously different for series A and series B. In addition, one complex [Pt(μ‐Cl)(EtEug)]2 and five complexes [PtCl(arylolefin)(NHC)] have been characterized by single crystal XRD. [ABSTRACT FROM AUTHOR]

A synthetic route towards homodiselenacalix[4]arene macrocycles is presented, based on the dynamic covalent chemistry of diselenides. The calixarene inner rim is decorated with either alkoxy or tert-butyl ester groups. Single-crystal X-ray analysis of two THF solvates with methoxy and ethoxy substituents reveals the high similarity of their molecular structures and alterations on the supramolecular level. In both crystal structures, solvent channels are present and differ in both shape and capacity. Furthermore, the methoxy-substituted macrocycle undergoes a single-crystal-to-single-crystal transformation during which the molecular structure changes its conformation from 1,3-alternate (loaded with THF/water) to 1,2-alternate (apohost form). Molecular modelling techniques were applied to explore the conformational and energetic behaviour of the macrocycles. [ABSTRACT FROM AUTHOR]

A new azide functionalized Anderson polyoxometalate was synthesized, fully characterized and subsequently used as a building block for further POM post-functionalization with organic compounds through a copper catalyzed azide–alkyne cycloaddition (CuAAC) reaction. Optimization of the reaction conditions led to an efficient, fast, convenient and versatile POM coupling method. [ABSTRACT FROM AUTHOR]

Successful co-crystallization of a noncovalent complex between hen egg-white lysozyme (HEWL) and the monomeric ZrIV-substituted Keggin polyoxometalate (POM) (Zr1 K1), (Et2NH2)3[Zr(PW11O39)] ( 1), has been achieved, and its single-crystal X-ray structure has been determined. The dimeric ZrIV-substituted Keggin-type polyoxometalate (Zr1 K2), (Et2NH2)10[Zr(PW11O39)2] ( 2), has been previously shown to exhibit remarkable selectivity towards HEWL hydrolysis. The reported X-ray structure shows that the hydrolytically active ZrIV-substituted Keggin POM exists as a monomeric species. Prior to hydrolysis, this monomer interacts with HEWL in the vicinity of the previously identified cleavage sites found at Trp28-Val29 and Asn44-Arg45, through water-mediated H-bonding and electrostatic interactions. Three binding sites are observed at the interface of the negatively charged Keggin POM and the positively charged regions of HEWL at: 1) Gly16, Tyr20, and Arg21; 2) Asn44, Arg45, and Asn46; and 3) Arg128. [ABSTRACT FROM AUTHOR]

A green multicomponent synthesis of previously unreported octahydropyrimido[4,5-g]quinazoline-5,6-diones was developed from simple building blocks. These highly symmetrical compounds show strong propensity to self-assembled molecular network (SAMN) formation on highly oriented pyrolytic graphite. The SAMN type is easily tunable by changing molecular characteristics. The redox behavior was studied by cyclic voltammetery. [ABSTRACT FROM AUTHOR]

The ionic liquid choline bis(trifluoromethylsulfonyl)imide, [Chol][Tf2N], was used for the extraction of neodymium(III), in combination with choline hexafluoroacetylacetonate, [Chol][hfac], as the extractant. The binary mixture of [Chol][Tf2N] and water shows temperature-dependent phase behavior, with an upper critical solution temperature of 72 °C. A novel extraction technique, homogeneous liquid-liquid extraction (HLLE), was applied to this solvent system. HLLE is based on the use of thermomorphic solvent mixtures and has the advantage of forming a homogeneous phase during mixing. Extraction is not kinetically hindered by an interface and the extraction equilibrium is reached faster than in the case of heterogeneous mixing in conventional solvent extraction. Several extraction parameters were studied for the extraction of neodymium(III) with [Chol][hfac]: temperature, pH, extractant concentration and loading of the ionic liquid phase. A speciation study was performed to determine the stoichiometry of the extracted neodymium(III) complex and a plausible extraction mechanism is proposed. Neodymium is extracted as a tetrakis hexafluoroacetylacetonate complex with one choline cation as counter ion. The crystal structure of the extracted complex showed the presence of a coordination bond between the choline counter ion and the neodymium(III) center, resulting in a coordination number of nine. The stripping of the loaded neodymium and the influence of acid and extractant concentrations on the phase behavior of the [Chol][Tf2N]-H2O system were investigated. [ABSTRACT FROM AUTHOR]

Three new complexes of Cu(II), Zn(II) and Cd(II) with bis(2-pyridyl)-di(4-methoxyphenyl)ethene (KT1), bis(µ2-chloro)-dichloro-bis(2-(2,2-di(4-methoxyphenyl)-1-(pyridin-2-yl)vinyl)pyridine)-di-copper(II) (CuKT1), dichloro-2-(2,2-di(4-methoxyphenyl)-1-(pyridin-2-yl)vinyl)pyridine-zinc(II) (ZnKT1) and hexakis(µ2-chloro)-dichloro-tetrakis(2-(2,2-di(4-methoxyphenyl)-1-(pyridin-2-yl)vinyl)pyridine)-tetra-cadmium(II) (CdKT1) were synthesized and characterized by IR spectroscopy, 1H NMR spectroscopy and single-crystal X-ray diffraction. The results reveal that ZnKT1 is a mononuclear complex, while CuKT1 and CdKT1 are binuclear and tetranuclear complexes, respectively. The central metal ions are surrounded by two N atoms of bis(2-pyridyl)-di(4-methoxyphenyl)ethene and Cl− ions including pendant and bridged ones. In the ZnKT1 complex, a distorted tetrahedral geometry is formed with Zn(II) as central ion and two chloride ions plus two nitrogen atoms of KT1 as surrounding atoms. CuKT1 is a binuclear complex with two square pyramids formed around the two Cu(II) ions. CdKT1 is a tetranuclear complex with two Cd(II) cations having coordination number six (distorted octahedral geometry) and the other two having coordination number five (distorted trigonal-bipyramidal geometry). The anticancer activity tests on four cancer cell lines, including KB, Hep-G2, Lu and MCF-7, show that ZnKT1 and CuKT1 are active against Hep-G2 and Lu but do not considerably damage KB and MCF-G7. CuKT1 has a considerable effect on two cancer cell lines, Hep-G2 and Lu, with IC50 values of 16(2) and 13(1) μM, respectively. CdKT1 exhibits excellent activity against all four cancer cell lines, with IC50 values ranging from 3.5(2) to 8.8(5) μM, which are lower than those of cisplatin. These complexes exhibit low cytotoxic activity on the normal cell line HEK-293A with IC50 values ranging from 10(1) to 74(5) µM. [ABSTRACT FROM AUTHOR]

The crystal structures of cis-dichlorido(ethylamine-κ N)(piperidine-κ N)platinum(II), [PtCl2(C2H7N)(C5H11N)], (I), cis-dichlorido(3-methoxyaniline-κ N)(piperidine-κ N)platinum(II), [PtCl2(C5H11N)(C7H9NO)], (II), and cis-dichlorido(piperidine-κ N)(quinoline-κ N)platinum(II), [PtCl2(C5H11N)(C9H7N)], (III), have been determined at 100 K in order to verify the influence of the nonpiperidine ligand on the geometry and crystal packing. The crystal packing is characterized by N-H...Cl hydrogen bonding, resulting in the formation of chains of molecules connected in a head-to-tail fashion. Hydrogen-bonding interactions play a major role in the packing of (I), where the chains further aggregate into planes, but less so in the case of (II) and (III), where π-π stacking interactions are of greater importance. [ABSTRACT FROM AUTHOR]

• Six new [Zn(2,4-diarylquinolin-8-olato) 2 ] complexes were synthesized. • Structures were characterized by ESI-MS, 1H NMR spectra and SC XRD. • Complexes exhibit fluorescence and electron-donating substituents enhance quantum yield. • Quantum chemical computations were consistent with experimental observations. Six new Zn(II) complexes (Zn1–Zn6) were synthesized from 2,4-diaryl-8-hydroxyquinoline derivatives (HQ1–HQ6) and structurally characterized by ESI-MS, 1H NMR spectra and SC XRD. The analysis of NMR and XRD results revealed that all the complex geometries are tetrahedral in which the ligands coordinated with Zn(II) via the N and O atoms. The investigation of photophysical properties showed that the ligands themself are non-fluorescent, while the complexes displayed a strong emission at 597–628 nm, characterized by a fluorescence quantum yield of 0.36–0.98 with a large Stokes shift of 174–202 nm, except complex Zn2. Notably, the quantum yields of the complexes in the solvents and emission intensity in the solid state tend to increase in the presence of electron-donating substituents. Quantum chemical computations were conducted to investigate the electronic structure and optical characteristics of the compounds, yielding outcomes consistent with experimental observations. [Display omitted] [ABSTRACT FROM AUTHOR]

Steviol glycosides were subjected to bacteria present in a soil sample collected from a Stevia plantation in Paraguay. During the incubation experiments, next to the aglycon steviol, steviol degradation products were also formed. X-ray analysis and NMR methods in combination with chemical synthesis and GIAO NMR calculations were used to fully characterize the structure of these compounds as a tricyclic ketone and the corresponding reduced form. They were nicknamed monicanone and monicanol. The latter has the (S)-configuration at the alcohol site. [ABSTRACT FROM AUTHOR]

[Display omitted] A series of complexes between bis(2-pyridyl)-di(4- n -butylphenyl)ethene (KT4) and bis(2-pyridyl)-di(3-methoxyphenyl)ethene (KT18) with transition metals Co(II), Cu(II), Zn(II), and Cd(II) were synthesized and crystallized. The structures of these compounds were confirmed based on IR, NMR, and MS spectra. Moreover, crystals were obtained for ZnKT18, CoKT18, CuKT18, CdKT18, and CdKT4. Single-crystal X-ray diffraction (XRD) demonstrated the ability of these pyridine-based ligands to coordinate to metal ions via two nitrogen atoms in the aromatic heterocycles. Depending on the central metal, they can form different structures. Zn(II) and Co(II) form mononuclear complexes with KT18 , where the metal coordinates to two N atoms and two chloride ions in a tetrahedral geometry (coordination number 4). The complexes CuKT18 , CdKT18 , and CdKT4 are binuclear complexes with one pendant chloride and two bridging chlorides coordinating with the metal ion (coordination number 5). The cytotoxic properties of free ligands and complexes were tested on four cancer lines, including KB, Hep-G2, Lu, and MCF-7. In general, the free ligands have no cytotoxic activity, while all complexes present strong to medium effects on these cancer lines. Several complexes are comparable in activity to cisplatin, a commercial drug used in the treatment of cancer. Specifically, ZnKT4 selectively inhibits the activities of the KB and Hep-G2 cell lines. CdKT4 has a high impact on Hep-G2 and Lu (IC 50 < 5 μM) while CdKT18 exhibits effective anticancer activity against the KB and MCF-7 cell lines. CuKT18 strongly inhibits the growth progress of the KB cancer cell (IC 50 = 9.52 μM). These IC 50 values are lower than those of cisplatin. [ABSTRACT FROM AUTHOR]

In our search for new easily accessible analogues based on the natural product podophyllotoxin, we synthesized 1-aza-4-deoxypicropodophyllotoxin in good overall yield and excellent enantioselectivity. The synthesis was centered around a direct asymmetric Mannich reaction using D-proline as the key step for introduction of the chiral centres. Our synthesis of 1-aza-4-deoxypodophyllotoxin was hindered through the increased instability towards epimerization of the C2 position. We did, however, synthesized a new scaffold based on the opened lactone analogue. [ABSTRACT FROM AUTHOR]

A series of novel substituted trioxa[7]helicenes have been successfully prepared by a one-pot palladium catalyzed C–H arylation reaction starting from readily prepared dibenzofuran fragments. The dinitro-substituted helicene was analyzed by X-ray crystallography revealing the occurrence of two distinct enantiomers in the asymmetric unit, which forms interesting supramolecular motifs in the crystal, based on weak H-bonding interactions. [ABSTRACT FROM AUTHOR]

Two series of 1-alkylpyridinium and N-alkyl-N-methylpiperidinium ionic liquids functionalized with a nitrile group at the end of the alkyl chain have been synthesized. Structural modifications include a change of the alkyl spacer length between the nitrile group and the heterocycle of the cationic core, as well as adding methyl or ethyl substituents on different positions of the pyridinium ring. The anions are the bromide and the bis(trifluoromethylsulfonyl)imide ion. All the bis(trifluoromethylsulfonyl)imide salts as well as the bromide salts with a long alkyl spacer were obtained as viscous liquids at room temperature, but some turned out to be supercooled liquids. In addition, pyrrolidinium and piperidinium ionic liquids with two nitrile functions attached to the heterocyclic core have been prepared. The crystal structures of seven pyridinium bis(trifluoromethylsulfonyl)imide salts are reported. Quantum chemical calculations have been performed on model cations and ion pairs with the bis(trifluoromethylsulfonyl)imide anion. A continuum model has been used to take solvation effects into account. These calculations show that the natural partial charge on the nitrogen atom of the nitrile group becomes more negative when the length of the alkyl spacer between the nitrile functional group and the heterocyclic core of the cation is increased. Methyl or methoxy substituents on the pyridinium ring slightly increase the negative charge on the nitrile nitrogen atom due to their electron-donating abilities. The position of the substituent (ortho, meta, or para) has only a very minor effect on the charge of the nitrogen atom. The 15N NMR spectra of the bis(trifluoromethylsulfonyl)imide ionic liquids were recorded with the nitrogen-15 nucleus at its natural abundance. The chemical shift of the 15N nucleus of the nitrile nitrogen atom could be correlated with the calculated negative partial charge on the nitrogen atom. [ABSTRACT FROM AUTHOR]

Abstract: A novel bidentate ligand, H8-BIFOL, was successfully prepared and resolved starting from readily available reagents. The reactivity and selectivity was evaluated in the alkynylation of benzaldehyde, resulting in ee’s up to 56%. [Copyright &y& Elsevier]

The article presents a research study on the organic compound, hexakis(adamantyktrimethyl-ammonium) cyclooctasilicate tetrateracontahydrate. It discusses an experiment that discovers the crystal structure and association of the subject compound to zeosils and the clathrate hydrates. Several sub groups of templates used to synthesize silicate hydrate materials include N-methyl quarternary amines, other quaternary amines and the metal-ethylenediamine complexes.

Cyclohexene nucleic acid (CeNA) building blocks can be introduced into natural DNA sequences without a large conformational influence because of the ability of the six-membered sugar ring to mimic both the C2′- endo and C3′- endo conformations of the naturally occurring ribofuranose sugar ring. The non-self-complementary DNA sequence d[GCG(xT)GCG]/d(CGCACGC) with one incorporated CeNA (xT) moiety crystallizes in two forms: orthorhombic and tetragonal. The tetragonal form, which diffracts to 3 Å resolution, is a kinetically stable polymorph of the orthorhombic form [Robeyns et al. (2010), Artificial DNA, 1, 1-7], which diffracts to 1.17 Å resolution and is the thermodynamically stable form of the CeNA-incorporated duplex. Here, the two structures are compared, with special emphasis on the differences in crystal packing and the irreversible conversion of the kinetic form into the high-resolution diffracting thermodynamic form. [ABSTRACT FROM AUTHOR]

Designed as a multivalent hydrogen bond acceptor, new receptors, Discopus 1a,b, were built from a triphenylene core surrounded by six (diaryl)phosphinate groups. An efficient synthesis was developed to prepare these elaborated structures in a high overall yield. The X-ray structure of receptor 1b showed strong cooperative hydrogen bonds with two water molecules and intermolecular CH-π contacts. In chloroform, Discopus la,b displayed recognition properties toward dihydroxybenzenes, selectively forming complexes with catechol derivatives 4a-c in a 1:2 (host:guest) stoichiometry. According to NMR and microcalorimetry titrations, association constants were found in the 30-2837 M-1 range, which were larger than those reported for curvated catechol receptors (14-120 M-1). Interestingly, Discopus present two distinct catechol binding sites. Weak hydrogen bonding between host phosphinates and guest hydroxyl groups was shown by infrared spectroscopy and 31P NMR. Molecular dynamics simulations and recognition experiments suggested that a stronger hydrogen bond assisted by a π-interaction between the Discopus core and one catechol molecule could exist within the 1:2 complex. [ABSTRACT FROM AUTHOR]

• A novel palladium catalysis to prepare C4-substituted phenanthridinones via N-arylation/aryl-aryl coupling. • Excellent chemo- and regioselectivity, functional group tolerance and moderate to excellent yield. • Further late-stage diversification of products for the synthesis of multiple-substituted phenanthridinones. An excellent chemo- and regioselective palladium-catalyzed cascade intermolecular N -arylation/aryl-aryl coupling process has been developed. Employing Pd(TFA) 2 , PCy 3 •HBF 4 , K 2 CO 3 and 1,4-dioxane in an oil bath at 100°C for 12 h, diverse C4-substituted phenanthridinones are synthesized from o -bromobenzamides in 42-92% yield. Broad substrate scope and excellent functional group tolerance are observed. The synthetic utility of this method is illustrated by the further derivatization to prepare multiple-substituted phenanthridinones in 30-75% yield. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The reaction of molybdate and dl-proline at pH 3.4 results in the formation of a Na4[Mo8O26(proO)2]·22H2O complex (pro=proline) in which two proline ligands are attached to molybdenum(VI) ions via monodentate coordination of the carboxylate groups. The structure of the complex was determined by single crystal X-ray diffraction and by combination of 1H, 13C and 95Mo NMR spectroscopy techniques in solution. The structure of the complex is strongly dependant on the pH. At native pH 3.4 the octamolybdate-type structure seems to be present in solution, but the increase of pH to 5.8 resulted in a rearrangement of the structure to a heptamolybdate-type structure. At physiological pH, the polyoxometalate framework was completely dissociated into the monomeric unit. The reactivity of the Na4[Mo8O26(proO)2]·22H2O towards the hydrolysis of ATP was tested at different pH values. While in solution at pH 3.4 the hydrolysis proceeded to yield AMP (adenosine monophosphate) and ADP (adenosine diphosphate) in nearly equal amounts, reaction mixture at pH 5.8 gave ADP as the only product of hydrolysis after 24h of reaction. At neutral pH, the hydrolysis of ATP was slower, but it proceeded to yield 75% of ADP after 48h of reaction. [Copyright &y& Elsevier]

CeNA oligonucleotides consist of a phosphorylated backbone where the deoxyribose sugars are replaced by cyclohexene moieties. The X-ray structure determination and analysis of a fully modified octamer sequence GTGTACAC, which is the first crystal structure of a carbocyclic-based nucleic acid, is presented. This particular sequence was built with left-handed building blocks and crystallizes as a left- handed double helix. The helix can be characterized as belonging to the (mirrored) A-type family. Crystallographic data were processed up to 1.53 Å, and the octamer sequence crystallizes in the space group R32. The sugar puckering is found to adopt the ³H2 half-chair conformation which mimics the C3′-endo conformation of the ribose sugar. The double helices stack on top of each other to form continuous helices, and static disorder is observed due to this end-to-end stacking. [ABSTRACT FROM AUTHOR]

The nonamer d(GCGAATTCG) and decamer d(GGCCAATTGG), containing one and two overhanging guanines, respectively, form G·GC triplets in their crystal packing. In order to introduce a third subsequent T·AT triplet, the decamer was further extended by one overhanging thymine residue. Two different crystal morphologies of the sequence d(TGGCCTTAAGG) were obtained by hanging-drop vapour diffusion and diffracted to 2.5 and 2.3 Å resolution, respectively. However, both crystals belong to the orthorhombic space group P212121, with similar unit-cell parameters. Therefore, the two data sets could be merged to a resolution of 2.4 Å with unit-cell parameters a = 26.97, b = 41.12, c = 52.72 Å. [ABSTRACT FROM AUTHOR]

Analyzes the exploration of the influence of 5-ido-2'-deoxyuridine incorporation on the structure of d[CACG(IDU)G]. Experimental observation of the analysis; Method used to study the analysis; Crystalization and data collections.

Single-crystal X-ray structure determinations of the complex between the minor-groove binder distamycin and d(GGCCAATTGG) reveal two 1 : 1 binding modes which differ in the orientation of the drug molecule in the minor groove. The two crystals were grown from different crystallization conditions and found to diffract to 2.38 and 1.85 Å, respectively. The structures were refined to completion using SHELXL-93, resulting in a residual R factor of 20.30% for the 2.38-Å resolution structure (including 46 water molecules) and 19.74% for the 1.85-Å resolution structure (including 74 water molecules). In both orienta- tions, bifurcated hydrogen bonds are formed between the amide nitrogen atoms of the drug and AT base pairs. With a binding site of at least five base pairs, close contacts between the terminal distamycin atoms and guanine amino groups are inevitable. The detailed nature of several of these interactions was further investigated by ab initio quantum chemical methods. [ABSTRACT FROM AUTHOR]