Influencia de los efectos cooperativos sobre las propiedades electrostáticas de nitroanilinas

El presente trabajo se desarrolla en una primera parte que consiste en el estudio de las estructuras cristalinas de una serie de anilinas y nitrobencenos con sustituyentes que presentan distinto grado de conjugación y capacidad para establecer puentes de hidrógeno. El análisis cuidadoso de las geometrías y de los patrones de empaquetamiento moleculares encontrados, unidos a algunos resultados de cálculos teóricos existentes en la literatura pusieron en evidencia la falta de datos experimentales confiables que permitieran establecer: a) el grado de planaridad del grupo amino en nitroanilinas primarias y su relación con la existencia de efectos cooperativos, b) la real importancia en el patrón de PH de la interacción C-H...O, que comprende a un hidrógeno bencénico en posición orto al amino y un O del grupo nitro, c) la validez del modelo de formación de cadenas polares a partir de puentes de hidrógeno bifurcados y d) la relación de la asimetría molecular, el grado de conjugación intramolecular y la capacidad molecular para establecer puentes de hidrógeno con la obtención de cristales no- centrosimétricos. A fin de aportar al esclarecimiento de los puntos mencionados en la segunda parte se profundiza el estudio de la 2-metil-5-nitroanilina (2M5NA), compuesto que a pesar de cristalizar en un grupo centrosimétrico, presenta un esquema de PH similar a su isómero la 2-metil-4- nitroanilina (MNA). En paralelo con el estudio de la densidad experimental de carga de la 2M5NA: 1) se revisaron los resultados de un estudio similar realizado sobre la MNA para poder establecer las comparaciones sobe la base de análisis equivalentes.Tesis digitalizada en SEDICI gracias a la Biblioteca de Física de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta

Influencia de los efectos cooperativos sobre las propiedades electrostáticas de nitroanilinas

El presente trabajo se desarrolla en una primera parte que consiste en el estudio de las estructuras cristalinas de una serie de anilinas y nitrobencenos con sustituyentes que presentan distinto grado de conjugación y capacidad para establecer puentes de hidrógeno. El análisis cuidadoso de las geometrías y de los patrones de empaquetamiento moleculares encontrados, unidos a algunos resultados de cálculos teóricos existentes en la literatura pusieron en evidencia la falta de datos experimentales confiables que permitieran establecer: a) el grado de planaridad del grupo amino en nitroanilinas primarias y su relación con la existencia de efectos cooperativos, b) la real importancia en el patrón de PH de la interacción C-H...O, que comprende a un hidrógeno bencénico en posición orto al amino y un O del grupo nitro, c) la validez del modelo de formación de cadenas polares a partir de puentes de hidrógeno bifurcados y d) la relación de la asimetría molecular, el grado de conjugación intramolecular y la capacidad molecular para establecer puentes de hidrógeno con la obtención de cristales no- centrosimétricos. A fin de aportar al esclarecimiento de los puntos mencionados en la segunda parte se profundiza el estudio de la 2-metil-5-nitroanilina (2M5NA), compuesto que a pesar de cristalizar en un grupo centrosimétrico, presenta un esquema de PH similar a su isómero la 2-metil-4- nitroanilina (MNA). En paralelo con el estudio de la densidad experimental de carga de la 2M5NA: 1) se revisaron los resultados de un estudio similar realizado sobre la MNA para poder establecer las comparaciones sobe la base de análisis equivalentes.Tesis digitalizada en SEDICI gracias a la Biblioteca de Física de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta

Imidazolium fumarate

In the title compound, C3H5N2 +·C4H3O4 −, the dihedral angle between the imidazolium ring and the plane formed by the fumarate anion is 80.98 (6)°. In the crystal structure, inter­molecular O—H⋯O and N—H⋯O hydrogen bonds form extended chains along [100] and [01], creating a two-dimensional network

Highlighting Recent Crystalline Engineering Aspects of Luminescent Coordination Polymers Based on F-Elements and Ditopic Aliphatic Ligands

Three principal factors may influence the final structure of coordination polymers (CPs): (i) the nature of the ligand, (ii) the type and coordination number of the metal center, and (iii) the reaction conditions. Further, flexible carboxylate aliphatic ligands have been widely employed as building blocks for designing and synthesizing CPs, resulting in a diverse array of materials with exciting architectures, porosities, dimensionalities, and topologies as well as an increasing number of properties and applications. These ligands show different structural features, such as torsion an-gles, carbon backbone number, and coordination modes, which affect the desired products and so enable the generation of polymorphs or crystalline phases. Additionally, due to their large coordination numbers, using 4f and 5f metals as coordination centers combined with aliphatic ligands increases the possibility of obtaining different crystal phases. Additionally, by varying the synthetic conditions, we may control the production of a specific solid phase by understanding the thermo-dynamic and kinetic factors that influence the self-assembly process. This revision highlights the relationship between the structural variety of CPs based on flexible carboxylate aliphatic ligands and f-elements (lanthanide and actinides) and their outstanding luminescent properties such as solid-state emissions, sensing, and photocatalysis. In this sense, we present a structural analysis of the CPs reported with the oxalate ligand, as the one rigid ligand of the family, and other flexible dicarboxylate linkers with –CH2– spacers. Additionally, the nature of the luminescence properties of the 4f or 5f-CPs is analyzed, and finally, we present a novel set of CPs using a glutarate-derived ligand and samarium, with the formula [2,2′-bipyH][Sm(HFG)2 (2,2′-bipy) (H2O)2]•(2,2′-bipy) (α-Sm) and [2,2′-bipyH][Sm(HFG)2 (2,2′-bipy) (H2O)2] (β-Sm).Fil: D'Vries, Richard F.. Universidad Santiago de Cali; ColombiaFil: Gomez, Germán Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ellena, Javier Alcides. Universidade de Sao Paulo; Brasi

Probing intermolecular interactions in a diethylcarbamazine citrate salt by fast MAS 1 H solid-state NMR spectroscopy and GIPAW calculations

Fast magic-angle spinning (MAS) NMR is used to probe intermolecular interactions in a diethylcarbamazine salt, that is widely used as a treatment against adult worms of Wuchereria bancrofti which cause a common disease in tropical countries named filariasis. Specifically, a dihydrogen citrate salt that has improved thermal stability and solubility as compared to the free form is studied. One-dimensional 1H, 13C and 15N and two-dimensional 1H-13C and 14N-1H heteronuclear correlation NMR experiments under moderate and fast MAS together with GIPAW (CASTEP) calculations enable the assignment of the 1H, 13C and 14N/15N resonances. A two-dimensional 1H-1H double-quantum (DQ) –single-quantum (SQ) MAS spectrum recorded with BaBa recoupling at 60 kHz MAS identifies specific proton-proton proximities associated with citrate-citrate and citrate-diethylcarbamazine intermolecular interactions

Synthesis of novel O-acylated-D-ribono-1,5-lactones and structural assignment supported by conventional NOESY-NMR and x-ray analysis

A practical method for the structural assignment of 3,4-O-benzylidene-D-ribono-1,5-lactones and analogues using conventional NMR techniques and NOESY measurements in solution is described. 2-O-Acyl-3,4-O-benzylidene-D-ribono-1,5-lactones were prepared in good yields by acylation of Zinner’s lactone with acyl chlorides under mildly basic conditions. Structural determination of 2-O-(4-nitrobenzoyl)-3,4-O-benzylidene-D-ribono-1,5-lactone was achieved by single crystal x-ray diffraction, which supports the results based on spectroscopic data.Este trabalho apresenta um método simples para a caracterização estrutural de 3,4-O-benzilideno-D-ribono-1,5-lactonas e análogos, fundamentado em técnicas convencionais de RMN e experimentos de NOESY em solução. 2-O-Acil-3,4-O-benzilideno-D-ribono-1,5-lactonas foram preparadas em bons rendimentos a partir da acilação das lactonas de Zinner empregando cloretos de ácido sob condições básicas. A estrutura de 2-O-(4-nitrobenzoil)-3,4-O-benzilideno-D-ribono-1,5-lactona foi determinada por difração de raios-X e confirmou, de forma inequívoca, os dados espectroscópicos obtidos.CNPq - MC

Rational design, supramolecular synthesis and solid state characterization of two bicomponent solid forms of mebendazole

Two novel bicomponent solid forms of mebendazole (MBZ) were developed as a means to modulate its psychochemical and pharmaceutical properties. Supramolecular synthesis of MBZ A or C with perchloric or methyl sulfuric acids yields two salts of 1 : 1 stoichiometry, which were analyzed through single crystal X-ray diffraction. MBZ perchlorate crystallizes in the P21/n space group, while MBZ methyl sulfate crystallizes in the P1 space group. The API and its counterions are interconnected in both crystal packings by an R22(8) supramolecular motif. The 3-dimensional crystal structure is also stabilized by other strong intermolecular hydrogen bonds as well as non-classical interactions. FT-IR spectra are consistent with the inclusion of the anions in the crystal structure. MBZ perchlorate is stable up to 210 °C when it undergoes endothermic loss of the ester moiety. MBZ methyl sulfate is stable up to 160 °C when endothermic elimination of the methylcarbamate moiety occurs. The solubility behavior of MBZ perchlorate, studied by UV-visible spectroscopy, suggests an improvement by a factor of seven with respect to MBZ A, in the apparent solubility of MBZ in 0.1 mol L-1 HCl. Further experiments are required to evaluate both the stability of the solids and the maximum solubility of the API.Fil: Gutiérrez, Eduardo Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Godoy, Agustín Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Narda, Griselda Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Ellena, Javier. Universidade de Sao Paulo; Brasi

1-(o-Tol­yl)thio­urea

In the title compound, C8H10N2S, the o-tolyl group and the thio­urea core are planar. The mean planes of the two groups are almost perpendicular [82.19 (8)°]. The thio­urea group is in the thio­amide form, in which resonance is present. In the crystal structure, mol­ecules are linked by inter­molecular N—H⋯S hydrogen bonds, forming two infinite chains parallel to the (110) and (10) planes

Different coordination modes for disulfoxides towards diorganotin(IV) dichlorides. X-ray crystal structures of 1,2-cis-bis-(phenylsulfinyl)ethene (rac-,cis-cbpse) and adducts [{Ph2SnCl2(meso-bpse)}n] and [{n-Bu2SnCl2(pdtd)}2]

The reactions of meso-1,2-bis(phenylsulfinyl)ethane (meso-bpse) with Ph2SnCl2, 2-phenyl-1,3-dithiane trans-1-trans-3-dioxide (pdtd) with n-Bu2SnCl2 and 1,2-cis-bis-(phenylsulfinyl)ethene (rac-,cis-cbpse) with Ph2SnCl2, in 1:1 molar ratio, yielded [{Ph2SnCl2(meso-bpse)}n], [{n-Bu2SnCl2(pdtd)}2] and [{Ph2SnCl2(rac,cis-cbpse)}x] (x = 2 or n), respectively. All adducts were studied by IR, Mössbauer and 119Sn NMR spectroscopic methods, elemental analysis and single crystal X-ray diffractometry. The X-ray crystal structure of [{Ph2SnCl2(meso-bpse)}n] revealed the occurrence of infinite chains in which the tin(IV) atoms appear in a distorted octahedral geometry with Cl atoms in cis and Ph groups in trans positions. The X-ray crystal structure of [{n-Bu2SnCl2(pdtd)}2] revealed discrete centrosymmetric dimeric species in which the tin(IV) atoms possess a distorted octahedral geometry with bridging disulfoxides in cis and n-butyl moieties in trans positions. The spectroscopic data indicated that the adduct containing the rac,cis-cbpse ligand can be dimeric or polymeric. The X-ray structural analysis of the free rac-,cis-cbpse sulfoxide revealed that the crystals belong to the C2/c space group.As reações de meso-1,2-bis(fenilsulfinil)etano (meso-bpse) com Ph2SnCl2, de 2-fenil-1,3-ditiona trans-1-trans-dióxido (pdtd) com n-Bu2SnCl2 e de 1,2-cis-bis-(phenylsulfinyl)ethene (rac-,cis-cbpse) com Ph2SnCl2, na proporção molar 1:1, levaram à formação de [{Ph2SnCl2(meso-bpse)}n], [{n-Bu2SnCl2(pdtd)}2] e [{Ph2SnCl2(rac,cis-cbpse)}x] (x = 2 ou n), respectivamente. Na investigação das propriedades estruturais dos produtos foram empregadas as espectroscopias de absorção no infravermelho, Mössbauer e RMN de 119Sn, além de análise elementar e difratometria de raios X em monocristal. O estudo de [{Ph2SnCl2(meso-bpse)}n] por difratometria de raios X revelou a ocorrência de um encadeamento infinito no qual os átomos de tin(IV) apresentam uma geometria octaédrica distorcida com os átomos de Cl em posições cis e os grupos Ph em trans. A estrutura cristalina de [{n-Bu2SnCl2(pdtd)}2] revelou a presença de espécies diméricas centrossimétricas nas quais os átomos de tin(IV) possuem geometria octaédrica distorcida com dissulfóxidos em ponte ocupando posições cis e grupos n-butila ocupando posições trans. Os dados espectroscópicos indicaram que o produto contendo o ligante rac,cis-cbpse pode ser dimérico ou polimérico. O estudo por difratometria de raios X do sulfóxido rac-,cis-cbpse livre revelou que os cristais pertencem ao grupo espacial C2/c.CNPqFAPESPFINE