Fluorene Thiophene α-Cyanostilbene Hexacatenar-Generating LCs with Hexagonal Columnar Phases and Gels with Helical Morphologies as Well as a Light-Emitting LC Display

Two series of novel synthesized hexacatenars, O/n and M/n, containing two thiophene-cyanostilbene units interconnected by central fluorene units (fluorenone or dicyanovinyl fluorene) using a donor-acceptor-acceptor-donor (A-D-A-D-A) rigid core, with three alkoxy chains at each end, can self-assemble into hexagonal columnar mesophases with wide liquid crystal (LC) ranges and aggregate into organogels with flowerlike and helical cylinder morphologies, as revealed via POM, DSC, XRD and SEM investigation. Furthermore, these compounds were observed to emit yellow luminescence in both solution and solid states which can be adopted to manufacture a light-emitting liquid crystal display (LE-LCD) by doping with commercially available nematic LC.

Pyrrolo[3,2-b]pyrrole-1,4-dione (IsoDPP) End Capped with Napthalimide or Phthalimide: Novel Small Molecular Acceptors for Organic Solar Cells

We introduce two novel solution-processable electron acceptors based on an isomeric core of the much explored diketopyrrolopyrrole (DPP) moiety, namely pyrrolo[3,2-b]pyrrole-1,4-dione (IsoDPP). The newly designed and synthesized compounds, 6,6'-[(1,4-bis{4-decylphenyl}-2,5-dioxo-1,2,4,5-tetrahydropyrrolo[3,2-b]pyrrole-3,6-diyl)bis(thiophene-5,2-diyl)]bis[2-(2-butyloctyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione] (NAI-IsoDPP-NAI) and 5,5'-[(1,4-bis{4-decylphenyl}-2,5-dioxo-1,2,4,5-tetrahydropyrrolo[3,2-b]pyrrole-3,6-diyl)bis(thiophene-5,2-diyl)]bis[2-(2-butyloctyl)isoindoline-1,3-dione] (PI-IsoDPP-PI) have been synthesized via Suzuki couplings using IsoDPP as a central building block and napthalimide or phthalimide as end-capping groups. The materials both exhibit good solubility in a wide range of organic solvents including chloroform (CF), dichloromethane (DCM), and tetrahydrofuran (THF), and have a high thermal stability. The new materials absorb in the wavelength range of 300-600 nm and both compounds have similar electron affinities, with the electron affinities that are compatible with their use as acceptors in donor-acceptor bulk heterojunction (BHJ) organic solar cells. BHJ devices comprising the NAI-IsoDPP-NAI acceptor with poly(3-n-hexylthiophene) (P3HT) as the donor were found to have a better performance than the PI-IsoDPP-PI containing cells, with the best device having a VOC of 0.92 V, a JSC of 1.7 mAcm-2, a FF of 63%, and a PCE of 0.97%.

Accessing the Ene-Imine Motif in 1H-Isoindole, Thienopyrrole, and Thienopyridine Building Blocks

A pathway to a range of diverse heterocycles was developed using a nucleophilic cyclization strategy. Lactams and ene-imines are accessed in a few steps from a common precursor, and these moieties are further elaborated to directly provide pyrroles or pyridines with extended conjugation. Reaction conditions are mild, and a broad range of structural types are available within a few steps.

Metastable 9-Fluorenone: Blueshifted Fluorescence, Single-Crystal-to-Single-Crystal Reactivity, and Evaluation as a Multimodal Fingermark Visualization Treatment

A metastable form of 9-fluorenone (MS9F) has been characterized using Raman spectroscopy, fluorimetry, and X-ray diffraction techniques. MS9F emits blue fluorescence (λ_max =495 nm) upon 365 nm irradiation and undergoes a single-crystal-to-single-crystal (SCSC) transformation to reach the ground state form (GS9F) over approximately 30 minutes, whereupon it emits the expected green fluorescence. A structure-property relationship for this fluorescent behavior has been posited. MS9F and GS9F were applied as a means of visualizing latent fingermarks on a nonporous surface. This approach identified three different modes of fluorescent fingermark visualization using 9-fluorenone.