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Photo-switching of Stenhouse donor–acceptor adducts by a non-linear optical input.

Cocrystals of 2,7-dihydroxynaphthalene (DHN, or naphthalene-2,7-diol) with isoniazid (pyridine-4-carbohydrazide) (INH), denoted DHN–INH [C10H8O2·C6H7N3O, (I)], and piracetam [2-(2-oxopyrrolidin-1-yl)acetamide] (PIR), denoted DHN–PIR [C10H8O2·C6H10N2O2, (II)], were obtained by the solvent-assisted grinding method and characterized by IR spectroscopy, powder X-ray diffraction and single-crystal X-ray diffraction. Cocrystal (I) crystallized in the triclinic space group P\overline{1} and showed a 2:2 stoichiometry. DHN and INH molecules are connected by O—H...N(pyridine) and O—H...N(hydrazide) hydrogen bonds. Cocrystal (II) crystallized in the space group Pca21 with a 1:1 stoichiometry. DHN and PIR molecules are connected by O—H...O=C hydrogen bonds. The supramolecular architecture of cocrystal (I) showed interlinked supramolecular tapes; meanwhile, in cocrystal (II), interlinked supramolecular sheets were observed.

Sulfamethazine [N 1-(4,6-dimethylpyrimidin-2-yl)sulfanilamide] is an antimicrobial drug that possesses functional groups capable of acting as hydrogen-bond donors and acceptors, which make it a suitable supramolecular building block for the formation of cocrystals and salts. We report here the crystal structure and solid-state characterization of the 1:1 salt piperidinium sulfamethazinate (PPD+·SUL−, C5H12N+·C12H13N4O2S−) (I). The salt was obtained by the solvent-assisted grinding method and was characterized by IR spectroscopy, powder X-ray diffraction, solid-state 13C NMR spectroscopy and thermal analysis [differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)]. Salt I crystallized in the monoclinic space group P21/n and showed a 1:1 stoichiometry revealing proton transfer from SUL to PPD to form salt I. The PPD+ and SUL− ions are connected by N—H+...O and N—H+...N interactions. The self-assembly of SUL− anions displays the amine–sulfa C(8) motif. The supramolecular architecture of salt I revealed the formation of interconnected supramolecular sheets.

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A family of pentacoordinated diorganotin(IV) compounds was synthesized and characterized through the advantageous approach of a multicomponent methodology involving the reaction between 4-(diethylamino)salicylaldehyde, dibutyltin oxide and including a series of l -amino acid fragments (alanine, valine, leucine, isoleucine, phenylalanine, tyrosine and methionine), all carried out in one-step, in excellent yields. Structures were elucidated by FTIR, HRMS and solution NMR (1H, 13C and 119Sn). Diorganotin(IV) derivatives crystallized easily and five unreported molecular structures were solved and analyzed by SC-XRD experiments; depending on the orientation of the alkyl residues different isomorphic arrays were found. Finally, pentacoordinated diorganotin(IV) complexes were tested against tumoral cell lines, HCT-15 (colon adenocarcinoma), HeLa (cervical uterine adenocarcinoma), MCF-7 (breast adenocarcinoma) and PC-3 (human prostate cancer) in order to evaluate their in vitro cytotoxicity.

Local microviscosity monitoring in living cells is a powerful tool to determine their healthy status in either a specific organelle or in the cytosol. Here is presented the rational design of a new family of self-calibrating dual-microviscosity probes as a strategy to improve the probe response at low viscosity ranges. We found one of the probes is useful to determine low viscosity variations in living cells where subtle stiffening of the rotor group in the probe can increase its viscosity sensitivity. Further X-ray structure analysis, fluorescence anisotropic measurements, and quantum chemical calculations of the electronic excitation by means of a natural transition orbital (NTO) analysis confirmed the observed response. The present work demonstrates that small viscosity variations (0.01–0.1 cP) in cells require improved analytical sensitivity to be properly monitored.

A chelating coumarin-derived ligand sensitizes all emitting lanthanide ions in the solid state and gives high absolute quantum yields for ethanol solutions of complexes of Sm, Eu, Tb, and Dy, above 20% for the last two. Crystal structures of these four complexes are [Ln(Cum)3(H2O)(X)]·X where X = MeOH or EtOH.

Chromophoric coumarin-BODIPY derivatives bridged by an ethynyl π-bridge were investigated as supramolecular building blocks of organic semiconducting solids through X-ray analysis, UV/Vis and fluorescence measurements, and quantum chemical calculations of the frontier orbital energy depending on the chemical environment. Based on a push-pull architecture, the molecular properties of 7-(diethylamino)coumarin core end-capped with BODIPYs as well as the supramolecular self-assembly can be directed through the modification of the ethyny-aryl π-bridge and the intermolecular interactions it generates. Frontier orbital energy changes depending on chemical environment were performed, in particular, upon adsorption on a flat semiconducting surface. Coumarin-BODIPY building-blocks self-assemble into molecular crystals and highly-ordered thin-films with desirable periodic π-stacking interactions for semiconducting applications. The present work represents a convenient alternative to engineer organic semiconducting solids based on coumarin-BODIPY systems for organic electronics.

In this work, we describe the synthesis of meso-(9-ethyl-9H-carbazol-3-yl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene and its incorporation as thin film by vapor deposition on indium tin oxide. The morphology of the film was analyzed by scanning electron microscopy and atomic force microscopy showing a granular and homogeneous structure, contact angle measurements revealed that this film exhibits a hydrophobic surface. Packing of the compound was simulated through molecular dynamics and Monte Carlo sampling, and the electronic features of aggregates were modeled with plane-wave DFT. A semiconductor behavior for the featured compound in aggregated state, which compares well with systems applied on electronic devices, is predicted for the featured F-BODIPY.

International audience; Nonlinear optical (NLO) properties of push-pull Mo complexes with ONO tridentate ligands have been studied. The compounds were obtained in high yields using multicomponent reactions and their structures were confirmed by NMR, IR and HRMS analysis. Furthermore, TGA studies revealed good thermal stability of the Mo complexes. The linear and NLO properties evidenced enhanced responses compared with their boron and tin analogs, indicating that Mo complexes should be further investigated as robust building blocks for NLO materials.

Molecular crystals of meso-(5-((4-formylphenyl)ethynyl)thiophen-2-yl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene 4a and meso-(4-((4-formylphenyl)ethynyl)phenyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene 4b were synthesized using palladium(0)-catalyzed Sonogashira cross coupling reactions and characterized using an experimental-theoretical approach. The crystal structures of F-BODIPYs 4a-b are structurally analogous, yet their crystal packing motifs displayed remarkable differences due to contrasting hydrogen-bonding interactions. A CASTEP study of the unit cell for each compound provided the theoretical band structure and density-of-states (DOS) diagrams for each molecular crystal, suggesting a semiconductor character for both solids. Analysis of the computed electron density with Bader's QTAIM describes the intermolecular-contact network within each periodic system, while Natural Bonding Orbitals (NBO) display in-phase overlap between stacked units, denoting intermolecular delocalization of the electron density via stacking. TDDFT analysis of solution UV-Vis spectra gives insight into the nature of the observed excitations along with the effects derived from the relative rotation of π-subsystems in solution.

BODIPY-derived molecular fluorescent rotors are one of the most useful families of fluorescent probes for the quantitative measurement of microviscosity. Here, we report the photophysical properties of two molecular rotors as ratiometric viscosity sensors, meso-(4-(9H-fluoren-2-yl)ethynyl)phenyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (1) and meso-(5-(9H-fluoren-2-yl)ethynyl)thiophen-2-yl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (2) having two independent chromophores; one (fluorene) is not influenced by viscosity and is used to determine concentration properties, and the other chromophore (BODIPY) acts as a molecular rotor. The fluorescence ratiometric calibration against microviscosity for the most sensitive probe (1), was obtained in a wide linear dynamic range. The sensitivity of the spectroscopic observables for 1 and 2 towards solvent viscosity and the typical analytical interfering solvent polarity and polarizability parameters were investigated by means of two different solvent scales, namely Lippert–Mataga and Catalan, finding consistent results. Quantum chemical calculations were conducted to analyze the probe mechanism in terms of Natural Transition Orbitals (NTOs) and the spatial extent of charge transfer excitations.

The crystal packing of the compound is described by an inter­molecular arrangement with the mol­ecules as inter­laced layers in a zigzag fashion, denoting inter­acting self-complementary dimers mainly by the localization of weak hydrogen bonds in a head-to-tail arrangement., The title chalcone derivative, C13H10O2, adopts an E conformation about the C=C double bond. The mol­ecule is composed of a furanyl and a phenyl ring, bridged by an α,β-unsaturated carbonyl system, which are inclined to one another by 24.07 (7)°. In the crystal, mol­ecules are connected by weak C—H⋯O hydrogen bonds involving the carbonyl O atom acting as a trifurcated acceptor and C—H⋯π inter­actions, forming ribbons extending along the c-axis direction.

Here is reported the use of a titanium oxide:fullerene (TiO x :PC 71 BM) composite film as electron collector layer in organic photovoltaic devices (OPV cells). OPV cells were fabricated under the bulk heterojunction architecture: the active layer was a blend of either the photoconductor polymer MEH–PPV or P3HT with the fullerene derivative PC 71 BM. As cathode the eutectic alloy of Bi, In and Sn, known as Field’s metal, was used. The melting point of this alloy is above 62 °C, which makes it suitable for a vacuum-free deposition process and easy and fast device test. Cell fabrication and testing were carried out at normal room conditions. For OPV cells based on MEH–PPV, the composite thin electron collector layer improved the power conversion efficiency ( η ) from 1.12% to 2.07%, thus the η increase was about 85%. Meanwhile, for devices based on P3HT the use of the composite film improved the photocurrent in almost 1 mA/cm 2 and the efficiency slightly increase from 2.48% to 2.68%.

The synthesis and structural characterization of six 1,4-diazepanes prepared by condensation of 2,2′-(1,3-propanediyldiimino)diphenols with glyoxal or 2,3-butanedione to give bisbenzoxazolidines and subsequent reduction with BH3–DMS is reported. The new 1,4-diazepanes were obtained in yields between 75% and 83% and characterized by NMR, IR, and HRMS. In addition, the crystal structure analysis showed that the seven-membered ring in 1,4-diazepanes (12a, 12e, and 12d) and bisbenzoxazolidines (11a, 11c, 11f) adopt in all cases twisted chair conformation. Compounds 12a and 12e show disorder in the seven member ring, as a result of the conformational flexibility of the seven-membered ring.

N-heterocyclic norbornene Dicarboximides were synthesized by reacting the exo-norbornene-5,6-dicarboxylic anhydride with 2-, 3-, and 4-aminopyridine. The amides resulting from 3 and 4-aminopyridine derivatives were converted into the corresponding betaines via Menshutkin reaction using ethyl-bromoacetate. The chemical structures of the obtained products were confirmed by FT-IR and 1 H and 13 C NMR spectroscopy, EA and MS as well as by calculation of 1 H and 13 C NMR chemical shifts using the GIAO method (PW91/6-311G++ (3df, 3pd) approximation by GAUSSIAN and PW91/IGLO-III approximation by deMon2k).

In this work we report the synthesis and spectroscopic characterization of twenty new pentacoordinated diorganotin(IV) compounds. These compounds have been prepared in good yields by multicomponent reactions (MCRs) of α-amino acids (isoleucine, leucine, methionine, phenylalanine and aminophenylacetic acid), 2,4-dihydroxybenzaldehyde, 2-hydroxy-4-methoxybenzaldehyde and either di-n-butyltin(IV) oxide or diphenyltin(IV) oxide. All compounds were characterized by IR spectroscopy, 1H, 119Sn and 13C NMR spectroscopy and mass spectrometry. Each compound has a coordinative N→Sn bond and shows the expected 119Sn NMR chemical shift indicative of a pentacoordinated or hexacoordinated tin atom in CDCl3 and DMSO-d6, respectively. These compounds were also tested in tumoral cell lines, HeLa, HCT-15 and MCF-7, in order to evaluate the antiproliferative activity and to obtain the medial inhibitory concentrations (IC50) values.

The synthesis and characterization of a set of poly(aryl ether) dendrimers with tetraphenylporphyrin as the core and 4, 8, 16, or 32 closo-carborane clusters are described. A regioselective hydrosilylation reaction on the allyl-terminated functions with carboranylsilanes in the presence of Karstedt’s catalyst leads to different generations of boron-enriched dendrimers. This versatile approach allows the incorporation of a large number of boron atoms in the dendrimers’ periphery. Translational diffusion coefficients (D) determined by DOSY NMR experiments permit estimation of the hydrodynamic radius (RH) and molecular size for each dendrimer. Furthermore, a notable correlation between D and the molecular weight (MW) is found and can be used to predict their overall size and folding properties. The UV–vis and emission behavior are not largely affected by the functionalization, therefore implying that the presence of carboranes does not alter their photoluminescence properties.

The excited triplet states of a set of water-soluble 4-sulfonatophenyl meso-bis and meso-tetrakis substituted porphyrinoids were studied in a wide range of concentrations. All of these porphyrinoids show the formation of π-stacked aggregates (H aggregates). As a consequence of the 5,15-diaryl substitution, and of aggregation, two excited triplet states can be detected, the more stable being accessible only by internal conversion of the current excited-state T1. The aggregates showed a significant singlet oxygen quantum yield [1O2 (1Δg), determined by the phosphorescence method], which in most cases was of the same order as the monomeric forms.

International audience; Molybdenum complexes of type [MoO2L](n) (L = tridentate ONO Schiff base ligands based on the salicylidene-2-aminophenolato structure) have been synthesized and used as catalysts for the solvent-free epoxidation of olefins. The effect of donor (diethylamino) and/or acceptor (nitro) substituents has been studied.

The effect of the addition of β- and γ-cyclodextrin (β-CD, γ-CD) to water solutions ( D 2 O ) of the 4'-sulfonato derivatives of meso-tetraphenylporphyrin (TPPS4, TPPS3, TPPS2o and TPPS2a) was studied by 1 H NMR at several temperatures. In all cases the disaggregation of the porphyrin homoassociates was detected, although in most cases it was only partial. Nuclear Overhauser signals (ROESY) show that cyclodextrin inclusion complexes were formed with TPPS4, TPPS3, and TPPS2o, but not with TPPS2a. These complexes include the sulfonatophenyl groups as guest, but not the hydrophobic phenyl substituents. The geometry of the complexes corresponds to that in which the sulfonatophenyl substituent is introduced through the secondary face of β-CD and through the primary face of γ-CD. In the inclusion complexes the polar sulfonato group is inside the cyclodextrin cavity but near to the hydrophilic interface with the bulk water. This explains the absence of complexation in the case of cationic porphyrins such as 5,10,15,20-tetrakis(N-methylpyridin-4-yl)porphyrin (TMPyP), and the decrease in the solubility when the β-CD complex of 5,15-bis(4-sulfonatophenyl)porphyrin (DPPS2o) forms. Complexes of the cyclodextrins with porphyrin homoassociates were also detected. This indicates that the heteroassociation avoids the formation of staggered stacks of porphyrin homoassociates, but has less effect on the association through the hydrophobic region of the phenyl substituents. This last type of aggregation, which is not significantly affected by the addition of α-CD, explains why the hydrophobic phenyl substituents are not complexed by the cyclodextrins.

The sulfonation of 5,15-bis(phenyl)porphyrin (DPP) in concentrated sulfuric acid results in substitution on the β-pyrrolic positions and the expected sulfonation on the para positions of the phenyl substituents. The sodium salt of 5,15-bis(4-sulfonatophenyl)porphyrin-2-sulfonic acid ( S 3 DPP ) was prepared in good yield, the sodium salts of 5,15-bis(4-sulfonatophenyl)porphyrin ( S 2 A DPP ), 5-phenyl-15-(4-sulfonatophenyl)porphyrin-2-sulfonic acid ( S 2 B DPP ) and 15-phenyl-5-(4-sulfonatophenyl)porphyrin ( S 1 A DPP ) were isolated, and 5,15-bis(phenyl)porphyrin-2-sulfonic acid ( S 1 B DPP ) was detected in a mixture with S 1 A DPP . The β-pyrrole sulfonato substituents are stable and their potential synthetic use is shown by the preparation of the trisodium salt of 10-bromo-5,15-bis(4-sulfonatophenyl)porphyrin-2-sulfonic acid ( BrS 3 DPP ) by NBS bromination of S 3 DPP . In a methanol/sulfuric acid mixture the sulfonation occurs on the meso positions, and the tetrasodium salt of 10,20-bis (4-sulfonatophenyl)porphyrin-5,15-disulfonic acid ( S 4 DPP ) was obtained.

A family of 15 N-substituted phenothiazines was designed, synthesized and their acaricidal activity against Rhipicephalus microplus was determined in vitro. The synthetic methodology is simple and can be employed in multigram scale. The rationale for the structure-based design of these compounds is the potential for azines and phenothiazine to engage in π–π interactions; these fragments, joined together by a short, flexible alkoxide linker, structurally resemble phenothiazine-based cholinesterase inhibitors, while their weak basicity implies a neutral active form, rather than a cationic one, thus facilitating penetration of the cuticle of ticks. One compound displayed excellent acaricidal activity (LD 50 = 0.58 μg/mL). Preliminary SAR analysis suggests that the activity is influenced by the presence of a weakly basic nitrogen atom, as well as the substitution pattern within the heterocycles.

The tautomeric equilibria and H−N proton transfer taking place in the nonsymmetrically substituted water-soluble 2-sulfonato-5,15-bis(4-sulfonatophenyl)porphyrin (1) and in its 10-bromo-substituted derivative (2) were analyzed by NMR methods: 1H and 13C spectroscopies and heteronuclear multiple bond correlation (HMBC) and heteronuclear single quantum coherence (HSQC) 1H−13C and 1H−15N techniques. The existence of preferred pathways of H−N transfer was detected. The conclusions are rationalized by taking into account the effect partial meso-substitution exerts on the relative energies of the different cis-tautomer intermediates involved in the tautomerism. These results underline the experimental consequences stemming from the nonequivalence in porphyrins between the ‘tautomeric interconversion' and ‘proton transfer' terms, when observed by NMR techniques, as a consequence of the existence of two pairs of degenerate tautomers and transformation pathways.

La Química, como todas las ciencias, utiliza un vocabulario especial con significados muy específicos. Una buena parte de la enseñanza y el aprendizaje de esta ciencia consisten en incorporar este lenguaje en forma tal que ayude a los alumnos a desarrollar la comprensión de los Conceptos Químicos (Sosa, 1999). Es preciso resaltar la relevancia y la plena vigencia del problema didáctico que plantea la comprensión de la magnitud cantidad de sustancia y de su unidad el mol, debido a las repercusiones que tiene a nivel de enseñanza y aprendizaje de la química. Este problema no se limita a los errores de los estudiantes en la comprensión y la utilización de estos conceptos, sino que tiene que ver con las ideas del profesorado y con las metodologías utilizadas en la enseñanza de los mismos (Hierrezuelo, 2006).

The self-assembly of diprotonated phenyl and 4-sulfonatophenyl meso-tetrasubstituted porphyrins gives a spontaneous chiral symmetry breaking, but only for H2TPPS3−, which forms helicoidal colloidal particles; the selection of the resulting chirality sign by the hydrodynamic forces of a stirring vortex can be demonstrated.