Truxene Moiety Research Articles

Metallo‐Supramolecular Octahedral Cages with Three Types of Chirality towards Spontaneous Resolution

Chirality is one of the most important intrinsic properties of (supra)molecules. In this study, we obtained enantiomeric metallo-supramolecular octahedra without using any chiral sources. Such cages were self-assembled by prochiral trispyridine ligand L based on a C3h truxene core and CuII salts. Crystallization of the cages with BF4 - as counterions afforded racemate crystals; while crystallizations of cages with ClO4 - and OTf- as counterions resulted in conglomerates with spontaneous resolution. Three types of chirality were observed in each cage, including planar chirality of the truxene core, axial chirality from the pyridyl and truxene moieties, and propeller chirality of the pyridyl-CuII coordination sites. The cages reported here are among the largest discrete synthetic metallo-supramolecules ever reported with chiral self-sorting behavior. Remarkably, the chiral cages exhibited very slow racemization even at low concentrations, suggesting their high stability in solution.

Metallo‐Supramolecular Octahedral Cages with Three Types of Chirality towards Spontaneous Resolution

AbstractChirality is one of the most important intrinsic properties of (supra)molecules. In this study, we obtained enantiomeric metallo‐supramolecular octahedra without using any chiral sources. Such cages were self‐assembled by prochiral trispyridine ligand L based on a C3h truxene core and CuII salts. Crystallization of the cages with BF4− as counterions afforded racemate crystals; while crystallizations of cages with ClO4− and OTf− as counterions resulted in conglomerates with spontaneous resolution. Three types of chirality were observed in each cage, including planar chirality of the truxene core, axial chirality from the pyridyl and truxene moieties, and propeller chirality of the pyridyl‐CuII coordination sites. The cages reported here are among the largest discrete synthetic metallo‐supramolecules ever reported with chiral self‐sorting behavior. Remarkably, the chiral cages exhibited very slow racemization even at low concentrations, suggesting their high stability in solution.

New 1,4-divinylbenzene conjugated truxene dyes possessing D-π-D structure: Synthesis, linear photophysics and two-photon absorption

A series of four 1,4-divinylbenzene linked truxene moieties with different substituents were synthesized by Horner-Wadsworth-Emmons reaction. Their structures were characterized using NMR spectroscopy and HRMS spectrometry. The photophysical properties of these molecules in solvents of different polarity were investigated by UV–vis absorption and fluorescence spectroscopy. These results show that these compounds have strong one-photon absorption bands in the near ultraviolet region displaying relatively high fluorescence quantum yields and large Stokes' shifts. In addition, these compounds possess good solid-state fluorescence, high two-photon absorption cross-section and high thermal stability.

New BODIPY derivatives with triarylamine and truxene substituents as donors for organic bulk heterojunction photovoltaic cells

We have designed two new BODIPY derivatives, denoted as 6a and 6b, substituted with truxene moiety and triphenylamine (TPA) unit groups and have investigated their optical and electrochemical properties. Dyes 6a and 6b were employed as donor along with PC71BM or Y6 as acceptor for the fabrication of binary and ternary organic solar cells. After optimization of the binary and ternary active layers, we have achieved over all power conversion efficiency (PCE) of 11.37 % and 13.32% for 6a:PC71BM:Y6 and 6b:PC71BM:Y6 ternary organic solar cells, respectively, which are higher than the binary organic solar cells based on PC71BM or Y6 acceptor. The higher power conversion efficiency for ternary OSC is possibly attributed to the better exciton generation rate, exciton dissociation and charge collection.

Chirality induction using circularly polarized light into a branched oligofluorene derivative in the presence of an achiral aid molecule.

Chirality induction into a uniform, star-shaped fluorene oligomer with a central truxene moiety (T3) was achieved using circularly polarized light in the presence of achiral fluorene or phenanthrene. Induction into T3 alone was difficult, suggesting that close chain packing realized through interactions of T3 with small molecules plays a role in chirality induction.

Efficient blue lighting materials based on truxene-cored anthracene derivatives for electroluminescent devices

Abstract A new series of anthracene derivatives containing a truxene moiety as the core have been synthesized and characterized. They emit in the blue region with excellent solution fluorescence quantum yields and possess high thermal decomposition temperature (Td>458 °C). Typical electroluminescence performance was demonstrated by 2-[10-(4-(1-napthenyl)phenyl)anthracene-9-yl]-5,5′,10,10′,15,15′-hexaethyltruxene (NPAT) as the blue lighting material in the OLED with structure of ITO/CFx/NPAT/TPBI or Alq3/LiF/Al, where TPBI and Alq3 are 1,3,5-tri(N-phenylbenzimidazol-2-yl)-benzene and tris(8-hydroxyquinolinato)aluminum, respectively. Additionally, the effects of the different thickness of the different electron transporting layers on the device performance were investigated.

Shape‐Persistent, Truxene‐Based, Nano‐Sized Bisterpyridine Ruthenium(II) Complexes: Synthesis and Photophysical Properties

A new series of shape-persistent metallomacromolecules G0 and G1 as well as corresponding ligands, based on thiophene-functionalized bisterpyridine-Ru(II) with truxene moieties, as the nodes, were developed. All new compounds were fully characterized by (1) H, COSY, and (13) C NMR, as well as MALDI-TOF MS. Their photophysical properties revealed that the branched scaffold resulted in high molar absorption coefficients and broad absorption making these materials potential candidates for light-harvesting.

Synthesis and Characterization of Novel Monodisperse Starburst Oligo(fluoreneethynylene) Based on Truxene Moiety

Abstract A series of novel monodisperse star-shaped oligo(fluoreneethynylene)s, which contain hexahexyltruxene as the central core linked with oligo(fluoreneethynylene) as the arms, are presented.

Nanosized Rigid π-Conjugated Molecular Heterojunctions with Multi[60]fullerenes: Facile Synthesis and Photophysical Properties

A series of large, rigid, new, well-defined, D-pi-B-A compounds with three chromophores (truxene moieties at the core, conjugated oligothiophenes as the branch bridges, and [60]pyrrolidinofullerene (C60) segments as the end-capped groups) have been facilely developed in this contribution. Oligothiophene-functionalized truxene derivatives 1-29 are prepared by the Suzuki, the Sonogashira, and the Negishi cross-coupling reactions catalyzed by Pd(PPh3)4 as well as the McMurry reaction, respectively. The 1,3-dipolar cycloaddition of the oligomers with C60 and N-methylglycine yields a new family of star-shaped D-pi-B-A derivatives end-capped with pyrrolidinofullerene moieties as the active materials for photovoltaic devices in which one, two, three, or four C60 moieties are allocated at the peripheral position of well-defined compounds, respectively. We also investigate the UV-vis and photoluminescence behaviors of these pyrrolidinofullerene-functionalized derivatives. The emission is obviously quenched after the inducement of the C60 moieties. We also observe that the emission intensity is decreased with the increase in the number of C60 moieties.

π-Conjugated Twin Molecules Based on Truxene: Synthesis and Optical Properties

[structure: see text] A series of novel extended pi-conjugated twin molecules based on 10,15-dihydro-5H-diindeno[1,2-alpha;1',2'-c]fluorene (truxene) have been prepared via Pd(0)-catalyzed Suzuki coupling, Sonogashira coupling, and McMurry reactions, respectively. 9,9'-Spirobifluorenylene, ethynylene, and vinylene groups as the bridge are introduced to connect both truxene moieties to understand the effect of the large steric chromophores on the properties of the desired materials. The investigation of optical properties of TM1-3 by UV-vis and photoluminescent spectroscopy demonstrates that the optical properties of the twin molecules are strongly affected by the pi-linkages.

Novel Blue-Light-Emitting Truxene-Containing Hyperbranched and Zigzag Type Copolymers: Synthesis, Optical Properties, and Investigation of Thermal Spectral Stability

Two series of novel alternating polyfluorene copolymers containing 10,15-dihydro-5H-diindeno[1,2-α;1‘,2‘-c]fluorene (truxene) moiety have been prepared through the Pd(0)-catalyzed Suzuki polymerization. The structure and purity of desired polymers is fully characterized by 1H and 13C NMR, UV−vis, and photoluminescent spectroscopy, gel permeation chromatography, elemental analyses, and TGA/DSC. The absorption and PL spectra of all polymers both in solutions and in thin films exhibit similar behaviors. For example, in solutions, the absorption spectra peak at about 360 nm, and the PL spectra show a maximum at about 390 nm with a shoulder at 412 nm. The introducing of the truxene moiety into polyfluorene and the hyperbranched and zigzag type molecular structures significantly reduce aggregation formation and enhance the thermal spectral stability of the desired polymers. They exhibit good solubility in common organic solvents as well as facile film forming properties. Bright blue emission is observed in both solution and solid states under UV excitation. The investigation of thermal spectral stability reveals that the long-wavelength emission upon thermal treatment usually observed in polyfluorene has been effectively reduced in our polymers.

Synthesis and Properties of Monodisperse Oligofluorene-Functionalized Truxenes: Highly Fluorescent Star-Shaped Architectures

This paper describes the strategy toward novel monodisperse, well-defined, star-shaped oligofluorenes with a central truxene core and from monofluorene to quaterfluorene arms. Introduction of solubilizing n-hexyl groups at both fluorene and truxene moieties results in highly soluble, intrinsically two-dimensional nanosized macromolecules T1-T4. The radius for the largest oligomer of ca. 3.9 nm represents one of the largest known star-shaped conjugated systems. Cyclic voltammetry experiments reveal reversible or quasi-reversible oxidation and reduction processes (Eox = +0.74 to 0.80 V, Ered = -2.66 to 2.80 eV vs Fc/Fc+), demonstrating excellent electrochemical stability toward both p- and n-doping, while the band gaps of the oligomers are quite high (EgCV = 3.20-3.40 eV). Close band gaps of 3.05-3.29 eV have been estimated from the electron absorption spectra. These star-shaped macromolecules demonstrate good thermal stability (up to 400-420 degrees C) and improved glass transition temperatures with an increase in length of the oligofluorene arms (from Tg = 63 degrees C for T1 to 116 degrees C for T4) and show very efficient blue photoluminescence (lambdaPL = 398-422 nm) in both solution (PhiPL = 70-86%) and solid state (PhiPL = 43-60%). Spectroelectrochemical experiments reveal that compounds T1-T4 are stable electrochromic systems which change their color reversibly from colorless in the neutral state (approximately 340-400 nm) to colored (from red to purple color; approximately 500-600 nm) in the oxidized state.

Extended pi-conjugated dendrimers based on truxene.

The largest pi-conjugated dendrimers containing up to nine 10,15-dihydro-5H-diindeno[1,2-alpha;1',2';-c]fluorene (truxene) moieties have been prepared with good yields by repetitive Friedel-Crafts acetylation and acid-promoted cyclotrimerization reactions. An alternative approach to the convergent synthesis of desired dendrimers has been developed, in which the core is generated "in-situ" by acid-promoted cyclotrimerizations of aryl methyl ketones. This proves valuable to afford large-size and precisely well-defined dendrimers in an accelerated dendrimer-growth strategy utilizing enlarged repeat units. The increasing amount of SiCl4 dramatically improves the yield of cyclotrimerization reactions. The introduction of hexahexyl groups onto C-5, C-10, C-15 positions of the truxene moiety greatly enhances the solubility of our compounds. Further investigation indicates that the torsion angle between the truxene segment and the benzene ring might play a key role in determining the photo properties of pi-conjugated dendrimers.