Hybrid iodoperfluoroalkane-ferrocene supramolecular arrays: the shortest contacts iodine forms with nitrogen atoms and unsaturated moieties

α,ω-Diiodoperfluoralkanes self-assemble in solution and in the solid phase with (S)-(−)-N,N-dimethyl-1-ferrocenylethylamine. The formed adducts have been characterized by DSC, IR, Raman, and NMR techniques. Single crystal X-ray analysis of one of the obtained adducts shows that perfluorinated and organometallic modules alternate giving rise to infinite one-dimensional (1D) chains. The interacting modules are connected through strong n-type halogen bondings, involving nitrogen and iodine atoms, and weak π-type halogen bondings, involving Cp rings and iodine atoms. Both interactions are the shortest reported to now in their respective classes. Theoretical calculations have been performed to quantify the observed π-type halogen bonding. For the first time a metallocene-perfluorocarbon (PFC) hybrid material is described.     

One-dimensional Supramolecular Chain Based on a Dinuclear Terbium(Ⅲ) 4-Cyanobenzoate Complex

A new dinuclear Tb(III) 4-cyanobenzoate complex [Tb2(4-cba)6(phen)2] (4-Hcba = 4-cyanobenzoic acid and phen = 1,10-phenanthroline) 1 has been synthesized by solvothermal reac- tion in an ethanol/water mixed solution at 100 ℃ and structurally characterized by single-crystal X-ray diffraction. Crystallographic data: C72H40N10O12Tb2, Mr = 1554.98, triclinic P1, a = 9.903(3), b = 11.769(8), c = 15.078(8) A, α = 111.42(12), β = 96.37(19), γ = 101.24(14)°, V = 1572(1) A3, Z = 1, Dc = 1.642 g/cm3, F(000) = 768 μ = 2.305 mm–1, the final R = 0.0205 and wR = 0.0543 for 5479 reflections with I > 2σ(I). Structural analysis shows that 1 displays an isolated dinuclear structure. Two eight-coordinated Tb(III) ions are bridged by four 4-cba ligands in the syn-syn bidentate coordination mode, and two other 4-cba ligands chelate these two Tb(III) ions. The title complex molecules are connected through π-π stacking interactions to generate a one-dimensional supra- molecular chain. The characteristic infrared spectra, luminescent properties and thermogravimetric analyses have also been discussed.     

New chemistry of diazafulvenium methides: one way to pyrazoles

Diazafulvenium methides generated from the solution pyrolysis of pyrazolo[1,5-c][1,3]thiazole-2,2-dioxides participate in [8π+2π] cycloadditions giving pyrazolo[1,5-a]pyridine derivatives. 1-Methyl-diazafulvenium, generated under flash vacuum pyrolysis reaction conditions, undergoes an intramolecular sigmatropic [1,8]H shift giving 1-vinyl-1H-pyrazoles.     

Donor-acceptor molecules containing thiophene chromophore: synthesis, spectroscopic study and electrogenerated chemiluminescence

Donor-acceptor molecules containing thiophene chromophore with remarkably large Stokes shift (>210 nm) have been found to exhibit strong and stable ECL emission via the singlet excited state without the addition of any co-reactant or a second compound.     

Synthesis and Fluorescent Behaviors of Polymers Bearing Stilbene Derivatives

A series of novel acrylate monomers bearing stilbene segments with D-π -A structure, 4-methacrylate-4′-nitro stilbene (NS), 4-(6-methacrylate)hexyl-4′-nitro stilbene (HNS) and 4-(6-methacrylate)hexyl-2,3-dimethoxy-4′-nitro stilbene (DMHNS), were synthesized by the Witting reaction and polymerized by free radical polymerization. These stilbene-containing monomers and polymers were fully characterized, and their fluorescent properties in solution and solid state were also investigated. The emission band of monomers and corresponding polymers in solution also showed a remarkable effect with increasing polarity of the solvent. More importantly, the fluorescence emission could be adjusted from green to orange and even red regions by forming donor-π -acceptor (D-π -A) construction.     

Polymorphism in a benzo[b][1,4]diazepine derivative: Crystal structure,phase behavior and selective influence of solvents

Ethyl 4-[(Z)-3-ethoxy-2,3-dioxopropylidene]-4,5-dihydro-1H-benzo[b][1,4]diazepine-2-carboxylate forms two polymorphic modifications α and β, which differ in molecular conformations, as well as in the dimension of H-bonded supramolecular motifs in crystals that are a 1D chain or a 0D dimer, respectively. The formation of polymorphs can be controlled by choice of the solvent used. Crystallization from a solution in a polar protic solvent, ethanol, results in the thermodynamically favorable α-form, while using a low-polarity solvent, chloroform, and melt crystallization lead to the metastable β-form.     

Tuning the Homo–Lumo Gap in Π-Bridged Bis(Phosphaalkenes)

Abstract

The HOMO–LUMO gap in a series of π-bridged bis(phosphaalkenes) is investigated by theoretical methods. The deshielding of the experimental ³¹P-NMR chemical shifts of a selection of these compounds does not correlate with a decrease of their calculated HOMO–LUMO gaps.     

New D-π-A-conjugated organic sensitizers based on α-pyranylidene donors for dye-sensitized solar cells

A series of new push-pull organic dyes incorporating a cyanoacrylic acid group as electron acceptor unit and α-chalcogenopyranylidene group (X = S; O) as electron donor unit has been synthesized, characterized and used as sensitizer for dye-sensitized solar cells (DSSCs). For the first time, α-pyranylidene and thiopyranylidene groups, have been evaluated in DSSC. To obtain the thermodynamic values of the solar cell, an investigation of their electrochemical (CV) and optical properties (UV–vis absorption spectroscopy) is also reported.     

Molecular complexity from aromatics. Cycloaddition of cyclohexa-2,4-dienones, sigmatropic 1,2-acyl shift and ring-closing metathesis: a new, efficient, and stereoselective synthesis of (±)-hirsutic acid C and medium ring carbocycles

A new, stereoselective formal synthesis of hirsutic acid and medium ring carbocyclic systems from salicyl alcohol is described. Cycloaddition between electron deficient partners such as cyclohexa-2,4-dienone and methylmethacrylate, triplet sensitized 1,2-acyl shift and ring-closing metathesis are the key features of our approach.