Density Functional Theory Investigation of Fulvene-Derivatized Fullerenes as Candidates for Organic Solar Cells.

Interest within the scientific community in organic solar cells has been on the rise over the last two decades as researchers respond to increasing demands for alternative renewable energy sources. Fulvene, fullerene, and endohedral metallofullerene derivatives have individually shown great promise as efficient charge transfer agents. Despite the heavy demand for research in this area, there have been no studies reported to date that explore the electronic behavior of molecules containing both fullerene and fulvene groups. The lack of interest may be attributed to inherent limitations and inaccuracy in most density functional theory (DFT) band gap calculations for large molecules. Herein we present a systematic computational investigation of the band gaps and dipole moments of several test fullerene-fulvene molecules using a novel DFT method that has been modified to allow accurate computation of the band gaps of this class of molecules. Calculated results showed promising low band gap energies and attractive conductive properties for all fullerene-fulvene derivatives. This new DFT method can conceivably be an invaluable tool that can provide predictive insight into the suitability of similar high molecular weight materials for application in organic solar cell devices.

Theoretical Explanation of Reaction Site Selectivity in the Addition of a Phenoxy Group to Perfluoropyridine.

Pentafluoropyridine, a potentially useful precursor in organofluorine methodology, undergoes selective substitution of a fluorine with a phenoxide at the site para to the nitrogen. Subsequent aryloxide substitutions can be accomplished at the ortho-positions with aryloxide groups containing various functional groups para to the phenoxide oxygen. During this phase of the reaction, "reverse reactions" involving substitutions of the original para substituent with a free fluoride or with another aryloxide moiety are observed with a frequency that depends on the functional group para to the oxygen on the aryloxide. Herein, we provide a theoretical explanation of these observations through use of density functional theory.

Single-pot extraction-analysis of dyed wool fibers with ionic liquids.

Analytical capabilities to identify dyes associated with structurally robust wool fibers would critically assist crime-scene and explosion-scene forensics. Nondestructive separation of dyes from wool, removal of contaminants, and dye analysis by MALDI- or ESI-MS, were achieved in a single-pot, ionic liquid-based method. Ionic liquids (ILs) that readily denature the wool α-keratin structure have been identified and are conducive to small volume, high-throughput analysis for accelerated threat-response times. Wool dyed with commercial or natural, plant-based dyes have unique signatures that allow classification and matching of samples and identification of dyestuffs. Wool released 0.005 mg of dye per mg of dyed wool into the IL, allowing for analysis of single-thread sample sizes. The IL + dye mixture promotes sufficient ionization in MALDI-MS: addition of common MALDI matrices does not improve analysis of anionic wool dyes. An inexpensive, commercially available tetrabutylphosponium chloride IL was discovered to be capable of denaturing wool and was determined to be the most effective for this readily fieldable method.

Single-crystal X-ray diffraction dataset for 3,5-difluoro-2,6-bis(4-iodophenoxy)-4-phenoxypyridine.

The data in this article are related to the research article "Utilizing the Regioselectivity of Perfluoropyridine towards the Preparation of Phenyoxyacetylene Precursors for Partially Fluorinated Polymers of Diverse Architecture."1 The X-ray structure analysis of 3,5-difluoro-2,6-bis(4-iodophenoxy)-4-phenoxypyridine has revealed an asymmetric unit containing two molecules, linked via both Type I and Type II C-I∙∙∙I-C halogen bonding interactions. The packing is further consolidated via Ar-H∙∙∙π interactions. This compound has been utilized for the synthesis of monomers for linear and network polymers.

Crystal structures and Hirshfeld surface analysis of a series of 4-O-aryl-perfluoro-pyridines.

Five new crystal structures of perfluoro-pyridine substituted in the 4-position with phen-oxy, 4-bromo-phen-oxy, naphthalen-2-yl-oxy, 6-bromo-naphthalen-2-yl-oxy, and 4,4'-biphen-oxy are reported, viz. 2,3,5,6-tetra-fluoro-4-phen-oxy-pyridine, C11H5F4NO (I), 4-(4-bromo-phen-oxy)-2,3,5,6-tetra-fluoro-pyridine, C11H4BrF4NO (II), 2,3,5,6-tetra-fluoro-4-[(naphthalen-2-yl)-oxy]pyridine, C15H7F4NO (III), 4-[(6-bromo-naphthalen-2-yl)-oxy]-2,3,5,6-tetra-fluoropyridine, C15H6BrF4NO (IV), and 2,2'-bis-[(perfluoro-pyridin-4-yl)-oxy]-1,1'-biphenyl, C22H8F8N2O2 (V). The dihedral angles between the aromatic ring systems in I-IV are 78.74 (8), 56.35 (8), 74.30 (7), and 64.34 (19)°, respectively. The complete mol-ecule of V is generated by a crystallographic twofold axis: the dihedral angle between the pyridine ring and adjacent phenyl ring is 80.89 (5)° and the equivalent angle between the biphenyl rings is 27.30 (5)°. In each crystal, the packing is driven by C-H⋯F inter-actions, along with a variety of C-F⋯π, C-H⋯π, C-Br⋯N, C-H⋯N, and C-Br⋯π contacts. Hirshfeld surface analysis was conducted to aid in the visualization of these various influences on the packing.

The chemometric resolution and quantification of overlapped peaks form comprehensive two-dimensional liquid chromatography.

The chemometric resolution and quantification of overlapped peaks from comprehensive two-dimensional (2D) liquid chromatography (LCxLC) data are demonstrated. The LCxLC data is produced from an in-house LCxLC analyzer that couples an anion-exchange column via a multi-port valve with a reversed-phase column connected to a UV absorbance detector. Three test mixtures, each containing a target analyte, are subjected to partial LCxLC separations to simulate likely cases of signal overlap. The resulting unresolved target-analyte signals are then analyzed by the standard-addition method and two chemometric methods. The LCxLC analyses of a test mixture and its corresponding standard-addition mixture results in two data matrices, one for each mixture. The stacking of these two data matrices produces a data structure that can then be analyzed by trilinear chemometric methods. One method, the generalized rank annihilation method (GRAM), uses a non-iterative eigenvalue-based approach to mathematically resolve overlapped trilinear signals. The other method, parallel factor analysis (PARAFAC), uses an iterative approach to resolve trilinear signals by the optimization of initial estimates using alternating least squares and signal constraints. In this paper, GRAM followed by PARAFAC analysis is shown to produce better qualitative and quantitative results than using each method separately. For instance, for all three test mixtures, the GRAM-PARAFAC approach improved quantitative accuracy by at least a factor of 4 and quantitative precision by more than 2 when compared to GRAM alone. This paper also introduces a new means of correcting run-to-run retention time shifts in comprehensive 2D chromatographic data.

Di(cyanate Ester) Networks Based on Alternative Fluorinated Bisphenols with Extremely Low Water Uptake.

A new polycyanurate network exhibiting extremely low moisture uptake has been produced via the treatment of perfluorocyclobutane-containing Bisphenol T with cyanogen bromide and subsequent thermal cyclotrimerization. The water uptake, at 0.56 ± 0.10% after immersion in water at 85 °C for 96 h, represents some of the most promising moisture resistance observed to date in polycyanurate networks. This excellent performance derives from a near optimal value of the glass transition at 190 °C at full cure. Superior dielectric loss characteristics compared to commercial polycyanurate networks based on Bisphenol E were also observed. Polycyanurate networks derived from this new monomer appear particularly well-suited for applications such as radomes and spacecrafts where polycyanurates are already widely recognized as providing outstanding properties.