Synthesis, structure and magnetic properties of tetrakis-μ-carboxylato-bis(dodecylnicotinato)dicopper(II) complexes; crystal and molecular structure of the decyl carboxylate derivative

Dodecylnicotinate bis-adducts of binuclear copper carboxylates, of the general formula Cu2(O2CCn-1H2n-1)4(C 5H4NCOOC12H25)2, were synthesized for n = 10, 12, 14, 16, 18 and 20, and their crystal structure, thermal behavior and magnetic properties studied. The molecular structure of the decyl derivative has been determined from single-crystal X-ray diffraction data. The dimer is centrosymmetric with the CuII ions in a square-pyramidal coordination with four O-alkyl O atoms [average d(Cu - O) 1.960 (6) Å] in the basal plane and the nicotine N atom at apical positions [d(Cu - N) 2.183 (3) Å]. The copper ions, 2.615 (1) Å apart, are bridged by four O-alkyl carboxylate groups. Both the n = 20 and n = 18 homologues exhibit lamellar phases, which can be related to the supramolecular arrangement found in the n = 10 derivative. The magnetic behavior of the decyl and octadecyl dimers was studied in the 2-300 K temperature range. They exhibit a strong intramolecular antiferromagnetic interaction (Cu-Cu superexchange coupling constant J = -347 cm-1 for the decyl derivative), which can be attributed to a large overlap of the metal 3d orbitals and the oxygen lone pair orbitals of the linking carboxylate groups.Fil: Rusjan, Marcia. Universidad Nacional de General Sarmiento; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Chaia, Zulema. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Piro, Oscar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Guillon, Daniel. Universite Paul Verlaine-Metz. Institut de Physique, Chimie et Materiaux; FranciaFil: Cukiernik, Fabio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad Nacional de General Sarmiento; Argentin

Halogen bonding in 1,2-dibromo-4,5-dimethoxybenzene and 1,2-diiodo-4,5-dimethoxybenzene

An interesting case of ‘halogen-bonding-promoted’ crystal structure architecture is presented. The two title compounds, C8H8Br2O2 and C8H8I2O2, have almost indistinguishable molecular structures but very different spatial organization, and this is mainly due to differences in the halogen-bonding interactions in which the different species present, i.e. Br and I, take part. The dibromo structure exhibits a Pi-bonded columnar array involving all four independent molecules in the asymmetric unit, with intercolumnar interactions governed by C—Br...Br—C links and with no C—Br...O/N interactions present. In the diiodo structure, instead, the C—I...O synthon prevails, de.ning linear chains, in turn interlinked by C—I...I—C interactions.8H8Br2O2 and C8H8I2O2, have almost indistinguishable molecular structures but very different spatial organization, and this is mainly due to differences in the halogen-bonding interactions in which the different species present, i.e. Br and I, take part. The dibromo structure exhibits a Pi-bonded columnar array involving all four independent molecules in the asymmetric unit, with intercolumnar interactions governed by C—Br...Br—C links and with no C—Br...O/N interactions present. In the diiodo structure, instead, the C—I...O synthon prevails, de.ning linear chains, in turn interlinked by C—I...I—C interactions.Fil: Cukiernik, Fabio Daniel. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: Zelcer, Andrés. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garland, Maria Teresa. Universidad de Chile; ChileFil: Baggio, Ricardo Fortunato. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentin

Relative influence of noncovalent interactions on the melting points of a homologous series of 1,2-dibromo- 4,5-dialkoxybenzenes

Crystal structures are presented for two members of the homologous series of 1,2-dibromo-4,5-dialkoxybenzenes, viz. those with decyloxy and hexadecyloxy substituents, namely 1,2-dibromo-4,5-bis(decyloxy)benzene, C26H44Br2O2, (II), and 1,2-dibromo-4,5-bis(hexadecyloxy)benzene, C38H68Br2O2, (III). The relative influences which halogen bonding, π- π stacking and van der Waals interactions have on these structures are analysed and the results compared with those already found for the lightest homologue, 1,2-dibromo-4,5- dimethoxybenzene, (I) [Cukiernik, Zelcer, Garland & Baggio (2008). Acta Cryst. C64, o604-o608]. The results confirm that the prevalent interactions stabilizing the structures of (II) and (III) are van der Waals contacts between the aliphatic chains. In the case of (II), weak halogen C - Br ⋯(Br - C) ′ interactions are also present and contribute to the stability of the structure. In the case of (III), van der Waals interactions between the aliphatic chains are almost exclusive, weaker C - Br ⋯ π interactions being the only additional interactions detected. The results are in line with commonly accepted models concerning trends in crystal stability along a homologous series (as measured by their melting points), but the earlier report for n = 1, and the present report for n = 10 and 16, are among the few providing single-crystal information validating the hypothesis.Fil: Fonrouge, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Cecchi, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Alborés, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Baggio, Ricardo Fortunato. Comisión Nacional de Energía Atómica; ArgentinaFil: Cukiernik, Fabio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

C-peptide and Retinal Microangiopathy in Diabetes

Increased extracellular matrix (ECM) protein deposition and capillary basement membrane (BM) thickening are characteristic features of diabetic retinal microangiopathy. Recent observations in the authors' laboratories suggest that high glucose in endothelial cells as well as diabetes causes up-regulation of total fibronectin (FN), as well as extradomain-B (EDB) containing the spliced variant of FN, oncofetal FN, in the retina. This splice variant is normally absent in mature adult tissues and is believed to be involved in angiogenesis. In this study, the authors have investigated the role of C-peptide in the production of ECM proteins and capillary BM thickening in the retina of diabetic rats. They investigated retinas from poorly controlled diabetic BB/Wor rats with or without C-peptide treatment as well as those from age-matched nondiabetic control rats after 8 months of diabetes. In addition, the authors investigated retinas from BBDRZ/Wor rats, a model of type 2 diabetes. Following a treatment period of 8 months, retinal tissues were harvested for gene expression and histological analyses. In the retinas of diabetic BB/Wor rats, a significant increase of oncofetal FN was demonstrated compared to control rats. C-peptide treatment of BB/Wor rats completely prevented such increase. Furthermore, retinas from BBDRZ/Wor rats, did not exhibit any such alteration in oncofetal FN expression. The authors further examined retinal capillary BM thickening using ultrastructural morphometry. C-peptide treatment was ineffective in preventing the diabetes-induced increase in capillary BM thickness. The authors' previous studies of cultured endothelial cells demonstrated that oncofetal FN synthesis is, at least in part, mediated via transforming growth factor-β (TGF-β) and endothelin-1 (ET-1). Hence, they examined these two transcripts in the retina of these animals. Diabetes caused significant increase in mRNA expression of ET-1 and TGF-β, which was not prevented by C-peptide treatment. Hence it appears that C-peptide is effective in preventing diabetes-induced oncofetal FN expression and that these effects are not mediated via ET-1 or TGF-β. In conclusion, these data suggest that C-peptide is involved in regulating ECM protein composition. Furthermore, normalization of diabetes-induced oncofetal FN up-regulation may suggest importance of C-peptide in advanced alterations in diabetic retinopathy such as angiogenesis

Alteration of Endothelins: A Common Pathogenetic Mechanism in Chronic Diabetic Complications

Endothelin (ET) peptides perform several physiological, vascular, and nonvascular functions and are widely distributed in a number of tissues. They are altered in several disease processes including diabetes. Alteration of ETs have been demonstrated in organs of chronic diabetic complications in both experimental and clinical studies. The majority of the effects of ET alteration in diabetes are due to altered vascular function. Furthermore, ET antagonists have been shown to prevent structural and functional changes induced by diabetes in animal models. This review discusses the contribution of ETs in the pathogenesis and the potential role of ET antagonism in the treatment of chronic diabetic complications

Polymorphism of a widely used building block for halogen-bonded assemblies: 1,3,5-Trifluoro-2,4,6-Triiodobenzene

After reporting the structure of a new polymorph of 1,3,5-Trifluoro-2,4,6-Triiodobenzene (denoted BzF3I3), C6F3I3, (I), which crystallized in the space group P21/c, we perform a comparative analysis with the already reported P21/n polymorph, (II) [Reddy et al. (2006). Chem. Eur. J.12, 2222-2234]. In polymorph (II), type-II I..I halogen bonds and I..π interactions connect molecules in such a way that a three-dimensional structure is formed; however, the way in which molecules are connected in polymorph (I), through type-II I..I halogen bonds and π-π interactions, gives rise to an exfoldable lamellar structure, which looks less tightly bound than that of (II). In agreement with this structural observation, both the melting point and the melting enthalpy of (I) are lower than those of (II).A new polymorph of 1,3,5-Trifluoro-2,4,6-Triiodobenzene is reported. On the basis of the experimental melting points and enthalpies, and also the calculated cohesion energies, the relative stabilities of both polymorphs have been established and analyzed in terms of the crystal structures and the noncovalent interactions present.Instituto de Física La Plat

Supramolecular organogels based on mesogenic 2,7-difunctionalized triphenylenes as a simple system for water content assessment in light alcohols

A series of three triphenylene compounds-denoted 2,7-THTP-DiCnOH-bearing four hexyloxy ancillary chains and two variable-length alkoxy chains terminally functionalized with hydroxyl groups have been synthesized and characterized. The studied compounds exhibited thermotropic mesomorphism; the detailed nature of the mesophases was found to depend on the relative positions of the terminal functional groups relative to the crown formed by the ancillary chains. All the studied compounds were able to act as supramolecular gelators in a variety of alcohols; their organogelating ability has been rationalized in terms of physicochemical parameters like the dielectric constant, which allowed us to establish very precise predictive "solvent gelation windows" for each compound. Remarkably stable gels have been detected for 2,7-THTP-DiC6OH in methanol. As a proof of principle, we present the water sensing performance as a rapid method for the assessment of water content in alcohol samples based on the influence that the water content exerts on the gels' thermostability.Fil: Vadra, Nahir. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Huck Iriart, Cristián. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Giovanetti, Lisandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Di Chenna, Pablo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; ArgentinaFil: Cukiernik, Fabio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

1,2-Diiodo-4,5-dimethyl­benzene

The structure of the title compound, C8H8I2, conforms closely to the mm2 symmetry expected for the free mol­ecule and is the first reported structure of a diiodo­dimethyl­benzene. Repulsion by neighboring I atoms and the neighboring methyl groups opposite to them results in a slight elongation of the mol­ecule along the approximate twofold rotation axis that bis­ects the ring between the two I atoms. In the extended structure, the mol­ecules form inversion-related pairs which are organized in approximately hexa­gonal close-packed layers and the layers then stacked so that mol­ecules in neighboring layers abut head-to-tail in a manner that optimizes dipole–dipole inter­actions

A liquid crystal derived from ruthenium(II,III) and a long-chain carboxylate

The title compound, catena-poly[[tetrakis(μ-decanoato-κ2O:O′)diruthenium(II,III)(Ru—Ru)]-μ-octanesulfonato-κ2O:O′], [Ru2(C10H19O2)4(C8H17O3S)], is an octane­sulfonate derivative of the mixed-valence complex diruthenium tetradecanoate. The equatorial carboxyl­ate ligands are bidentate, bridging two Ru atoms to form a dinuclear structure. Each of the two independent dinuclear metal complexes in the asymmetric unit is located at an inversion centre. The octane­sulfonate anion bridges the two dinuclear units through axial coordination. The alkyl chains of the carboxyl­ate and sulfonate ligands are arranged in a parallel manner. The global structure can be seen as infinite chains of polar moieties separated by a double layer of non-polar alkyl groups, without interdigitation of the alkyl chains.Facultad de Ciencias Exacta

Supramolecular organogels based on mesogenic 2,7-difunctionalized triphenylenes as a simple system for water content assessment in light alcohols

A series of three triphenylene compounds – denoted 2,7-THTP-DiCnOH – bearing four hexyloxy ancillary chains and two variable-length alkoxy chains terminally functionalized with hydroxyl groups have been synthesized and characterized. The studied compounds exhibited thermotropic mesomorphism; the detailed nature of the mesophases was found to depend on the relative positions of the terminal functional groups relative to the crown formed by the ancillary chains. All the studied compounds were able to act as supramolecular gelators in a variety of alcohols; their organogelating ability has been rationalized in terms of physicochemical parameters like the dielectric constant, which allowed us to establish very precise predictive “solvent gelation windows” for each compound. Remarkably stable gels have been detected for 2,7-THTP-DiC6OH in methanol. As a proof of principle, we present the water sensing performance as a rapid method for the assessment of water content in alcohol samples based on the influence that the water content exerts on the gels’ thermostability.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada