Molecular-Simulation-Inspired Synthesis of [6]-Prismane via Photoisomerisation of Octafluoro[2.2]paracyclophane.

Prismanes have been attracting interest for nearly 50 years because of their geometric symmetry, highly strained structures, and unique applications due to their high carbon densities and bulky structures. Although [3]-, [4]-, and [5]-prismanes have been synthesised, [6]-prismanes and their derivatives remain elusive. Herein, fluorine chemistry, molecular mechanics, molecular orbital package, and density functional theory calculations were used to design and implement the photoisomerisation of octafluoro[2.2]paracyclophane (selected based on the good overlap of its lowest unoccupied molecular orbitals and short distance between the benzene rings) into octafluoro-[6]-prismane. Specifically, a dilute solution of the above precursor in CH3CN/H2O/dimethyl sulfoxide (DMSO) (2:1:8, v/v/v) solution was irradiated with ultraviolet light, with the formation of the desired product confirmed through the use of nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. The product was thermally stable in solution but not under work-up conditions, which complicated the further analysis and single-crystal preparation. The key criteria for successful photoisomerisation were the presence of fluorine substituents in the cyclophane structure and DMSO in the solvent system. A more stable derivative design requires the isolation of prismane products. The proposed fluorination-based synthetic strategy is applicable to developing novel high-strain molecules/materials with three-dimensional skeletons.

Supramolecular Porphyrin-Based Metal-Organic Frameworks with Fullerenes: Crystal Structures and Preferential Intercalation of C70.

The syntheses and characterization of two new porphyrin-based metal-organic frameworks (P-MOFs), through the complexation of 5,10,15,20-tetra-4-pyridyl-21 H,23 H-porphine (H2 TPyP) and copper(II) acetate (CuAcO) in the presence of the fullerenes C60 or C70 are reported. Complex 1 was synthesized in conjunction with C60 , and this reaction produced a two-dimensional (2D) porous structure with the composition CuAcO-CuTPyP⊃m-dichlorobenzene (m-DCB), in which C60 molecules were not intercalated. Complex 2 was synthesized in the presence of C70 , generating a three-dimensional (3D) porous structure, in which C70 was intercalated, with the composition CuAcO-CuTPyP⋅C70 ⊃m-DCB⋅CHCl3 . The structures of these materials were determined by X-ray diffraction to identify the supramolecular interactions that lead to 2D and 3D crystal packing motifs. When a combination of C60 and C70 was employed, C70 was found to be preferentially intercalated between the porphyrins.

New porphyrin-based metal-organic framework with high porosity: 2-D infinite 22.2-A square-grid coordination network.

A new 2-D coordination network with 22.2-A square-grid coordination networks was prepared from a dicopper(II) tetraacetate [Cu2(AcO)4] as a linear linker motif and 5,10,15,20-tetra-4-pyridyl-21H,23H-porphine (H2TPyP) as a four-connected vertex, forming a regular high-porous structure. The characterization by N2 adsorption indicated that this coordination network has uniform micropores and gas adsorption cavities.

Enzymatic polymerization of coniferyl alcohol in the presence of cyclodextrins.

The dehydrogenative polymerization of coniferyl alcohol by horseradish peroxidase was performed in 0.10 M phosphate buffer at 27 degrees C. Dehydrogenative polymer (DHP) from coniferyl alcohol was characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. The ratio of 8-O-4':8-5':8-8' linkages was determined by the 1H NMR spectrum of DHP acetate which had good solubility. In "end-wise like" polymerization (the slow addition of hydrogen peroxide), addition of alpha-cyclodextrin to the medium led to DHP with increased 8-O-4' content and a decrease in 8-5' linkages. Under higher pH conditions, DHP with higher 8-O-4' and 8-5' content was obtained in the presence of alpha-cyclodextrin. In the end-wise polymerization (the slow additions of coniferyl alcohol and hydrogen peroxide), using alpha-cyclodextrin also gave DHP with a 8-O-4' richer structure than that prepared in no additive system. The analysis of thioacidolysis products from DHP supported the results of the alpha-cyclodextrin effects on the 8-O-4'-rich structure of DHP. The 8-O-4' structure in DHP prepared in the presence of alpha-cyclodextrin had racemic form as shown by ozonation.

Organic-inorganic hybrids from renewable plant oils and clay.

This study deals with the preparation and properties of a new class of organic-inorganic hybrids from renewable resources. The hybrids were synthesized by an acid-catalyzed curing of epoxidized triglycerides in the presence of an organophilic montmorillonite (a modified clay). The mechanical properties were improved by the incorporation of clay in the oil-based polymer matrix. The reinforcement effect due to the addition of clay was confirmed by dynamic viscoelasticity analysis. The hybrids showed relatively high thermal stability. The co-curing of epoxidized soybean and linseed oils in the presence of clay produced hybrids with controlled mechanical and coating properties. The barrier property of the hybrid towards water vapor was superior to that of the oil polymer. The development of the present hybrids consisting of inexpensive renewable resources, triglyceride and clay is expected to contribute to global sustainability.