Herringbone Infinite Networks Formed by Terpyridine and Haloperfluoroarene Modules

Abstract

4′-(4-Methylphenyl)-2,2′:6′,2″-terpyridine (1) self-assembles with dihaloperfluoroarenes (2). A chemo- and site-selective supramolecular synthesis occurs which preserves in the solid cocrystal the most stable s-trans, s-trans conformation of the pure terpyridine module. The single crystal X-ray structure of 3a, prepared from 1 and 1,4-diiodotetrafluorobenzene (2a) (monoclinic, a = 14.608(1), b = 13.276(1), c = 13.970(2) Å, β = 109.808(8)°, U = 2549.4 (4) ų, T = 291 (1) K, space group C2/c Z = 4; μ(Mo-Kα) = 2.519 mm^?1; d _calc.: 1.890 g cm^?3; 5748 reflections measured, 3715 unique (Rint = 0.024) which were used in all calculations; the final R and wR (F ²) were 0.043 and 0.069, respectively) shows the presence of infinite ribbons where the two modules alternate in a zigzag arrangement.     

Hybrid Calixarene/Inorganic Salt/Diiodoperfluorocarbon Supramolecular Assemblies

1,3-Bis(α-picolyloxy)-p-tert-butylcalix[4]crown-5 in the cone conformation (2), 1,8-diiodoperfluorooctane or 1,6-diiodoperfluorohexane, and potassium iodide ternary mixtures undergo in solution self-sorting and afford crystalline “supramolecular salts”. These hybrid materials consist of supercation [K⁺ ? 2] and superanion [I–(CF₂) _n –I…I^? …I–(CF₂) _n –I…I^? …] (n = 6,8) components. In the supercations the potassium ion is embedded in the ionophoric pocket created by the heteroatoms present at the lower rim. In the superanions the iodide ions form infinite fluorous polyanionic chains as a result of a self-assembly process which relies on halogen bonding. Both cation encapsulation and anion-perfluorocarbon halogen bonding were detected in solution by ¹H and ¹⁹F NMR, and in the gas phase by ESI MS.     

Binding energies and 19F nuclear magnetic deshielding in paramagnetic halogen-bonded complexes of TEMPO with haloperfluorocarbons

19F NMR measurements and theoretical calculations were performed to study paramagnetic complexes of iodoperfluorocarbons with stable nitroxide radicals. Contrary to what is usually measured for diamagnetic halogen-bonded complexes involving iodoperfluorocarbons, it was found that the formation of complexes with the 2,2,6,6-tetramethyl(piperidin-1-yloxyl) (TEMPO) radical determines downfield shifts in the 19F NMR spectra. The experimental finding was confirmed by calculating nuclear shielding using density functional theory and correcting the isotropic diamagnetic (19)F chemical shift with contact interactions evaluated from the hyperfine coupling tensor. The computational analysis of the interaction between CF3I and TEMPO, by using DFT and MP2 theories, showed that the occurrence of the halogen bond between the interacting partners is associated with a significant charge transfer to CF3I and that the measured downfield shift is due to the occurring spin transfer.     

Design of Highly Stable Echogenic Microbubbles through Controlled Assembly of Their Hydrophobin Shell

Dispersing hydrophobin HFBII under air saturated with perfluorohexane gas limits HFBII aggregation to nanometer‐sizes. Critical basic findings include an unusual co‐adsorption effect caused by the fluorocarbon gas, a strong acceleration of HFBII adsorption at the air/water interface, the incorporation of perfluorohexane into the interfacial film, the suppression of the fluid‐to‐solid 2D phase transition exhibited by HFBII monolayers under air, and a drastic change in film elasticity of both Gibbs and Langmuir films. As a result, perfluorohexane allows the formation of homogenous populations of spherical, narrowly dispersed, exceptionally stable, and echogenic microbubbles.     

Site- and orientation-selective anchoring of a prototypical molecular building block

The controlled anchoring of molecular building blocks on appropriate templates is a major prerequisite for the rational design and fabrication of supramolecular architectures on surfaces. We report on a particularly selective adsorption process of hexa-peri-hexabenzocoronene on Au(111), which leads to well-controlled adsorption position and orientation of the polycyclic aromatic hydrocarbons. Scanning tunneling microscopy reveals selective adsorption on monatomic steps in the fcc stacking regions with a specific orientation of 18 degrees between the molecular axis and the step normal. Ab initio calculations for various adsorption sites reveal the lowest total energy for adsorption on a kink site. Energy considerations and the excellent agreement between experimental and simulated images show that adsorption on kink sites is responsible for the specific adsorption angle.     

Tuning second-order NLO responses through halogen bonding

As a function of the ability of the solvent to behave as acceptor of halogen bonding, the NLO-phores under study give rise to microbeta(lambda) values ranging from +192 x 10(-48) esu to -465 x 10(-48) esu.     

A time series approach for clustering mass spectrometry data

Advanced statistical techniques and data mining methods have been recognized as a powerful support for mass spectrometry (MS) data analysis. Particularly, due to its unsupervised learning nature, data clustering methods have attracted increasing interest for exploring, identifying, and discriminating pathological cases from MS clinical samples. Supporting biomarker discovery in protein profiles has drawn special attention from biologists and clinicians. However, the huge amount of information contained in a single sample, that is, the high-dimensionality of MS data makes the effective identification of biomarkers a challenging problem.In this paper, we present a data mining approach for the analysis of MS data, in which the mining phase is developed as a task of clustering of MS data. Under the natural assumption of modeling MS data as time series, we propose a new representation model of MS data which allows for significantly reducing the high-dimensionality of such data, while preserving the relevant features. Besides the reduction of high-dimensionality (which typically affects effectiveness and efficiency of computational methods), the proposed representation model of MS data also alleviates the critical task of preprocessing the raw spectra in the whole process of MS data analysis. We evaluated our MS data clustering approach to publicly available proteomic datasets, and experimental results have shown the effectiveness of the proposed approach that can be used to aid clinicians in studying and formulating diagnosis of pathological states.     

LOW MACH NUMBER LIMIT ON EXTERIOR DOMAINS Dedicated to Professor Constantine M. Dafermos on the occasion of his 70th birthday

This paper is concerned with the low Mach number limit for the compressible Navier-Stokes equations in an exterior domain.We present here an approach based on Strichartz estimate defined on a non trapping exterior domain and we will be able to show the compactness and strong convergence of the velocity vector field.     

Halide anions driven self-assembly of haloperfluoroarenes: Formation of one-dimensional non-covalent copolymers

The supramolecular organization in six solid assemblies involving iodo- and bromoperfluoroarene derivatives is described. Single crystal X-ray analyses show that the formation of the supramolecular architectures is controlled by I⁻?Br–Ar_F, I⁻?I–Ar_F, Br⁻?I–Ar_F, and Cl⁻?I–Ar_F halogen bondings thus proving the X⁻?X′–Ar_F supramolecular synthon, where X can be the same as or different from X′, is particularly robust. In five of the described architectures halide anions form two halogen bondings and form infinite chains wherein dihaloperfluoroarenes, which function as bidentate electron acceptors, and halide anions, which function as bidentate electron donors, alternate. This behaviour shows halide anions have a fair tendency to work as bidentate halogen bonding acceptors.     

An infinite class of maximal intermediate propositional logics with the disjunction property

Summary Infinitely many intermediate propositional logics with the disjunction property are defined, each logic being characterized both in terms of a finite axiomatization and in terms of a Kripke semantics with the finite model property. The completeness theorems are used to prove that any two logics are constructively incompatible. As a consequence, one deduces that there are infinitely many maximal intermediate propositional logics with the disjunction property.