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π-Stacked dendrimers consisting of cofacially aligned donors and acceptors are developed by introducing three dendritic teracridan donors with orthogonal configuration and three triazine acceptors in periphery of hexaphenylbenzene skeleton. The dendritic structure and orthogonal configuration of teracridan not only make their outer acridan segments approaching to acceptor in close distance, but also fix donor and acceptor in face-to-face alignment, leading to through-space charge transfer emission with thermally activated delayed fluorescence (TADF) effect. By regulating charge transfer strength via substituent effect of acceptor, emission color of the dendrimers can be tuned from blue to yellow/red region. Solution-processed two-color white organic light-emitting diodes (OLEDs) based on blue and yellow π-stacked donor-acceptor dendrimers exhibit the maximum external quantum efficiency of 20.6 % and maximum power efficiency of 58.9 lm W-1 , representing the state-of-the-art efficiency for all-TADF white OLEDs by solution process.

Crafting of chiral plasmonic nanostructures is extremely important and challenging. DNA-directed organization of nanoparticle on a chiral template is the most appealing strategy for this purpose. Herein, we report a supramolecular approach for the design of DNA-decorated, helically twisted nanoribbons through the amphiphilicity-driven self-assembly of a new class of amphiphiles derived from DNA and hexaphenylbenzene (HPB). The ribbons are self-assembled in a lamellar fashion through the hydrophobic interactions of HPB. The transfer of molecular chirality of ssDNA into the HPB core results in the bias of one of the chiral propeller conformations for HPB and induces a helical twist into the lamellar packing, and leads to the formation of DNA-wrapped nanoribbons with M-helicity. The potential of the ribbon to act as a reversible template for the 1D chiral organization of plasmonic nanomaterials through DNA hybridization is demonstrated.

Host-guest chemistry is a functional model in supramolecular chemistry for understanding specific process occurring in biological systems. Herein, we describe a rationally designed giant multiarmed hexaphenylbenzene (HPB)-based supramolecular frameworks which encapsulate a variety of guest molecules in the voids of their crystal lattice through the cooperative interplay of multivalency, noncovalent forces and backbone rigidity. In this connection, pseudo-axially substituted twelve-armed hexaphenylbenzene was synthesized and its molecular entrapping nature was studied by varying number of H-bond donor-acceptor sites in the arms. The per-methyl esterified HPB acted as a cavitand to include nonpolar and polar aprotic guests in its crystal structure via C-H⋅⋅⋅π, C-H⋅⋅⋅O and C-H⋅⋅⋅N interactions. The corresponding amidated HPB showed unprecedented inclusion of ammonia and segregation of the guest molecules according to their polarity in the lattice. Furthermore, this molecular entrapping system has been used to obtain the crystal structure of a hitherto unproven 2-azaallenium intermediate, which had been proposed to be involved in aminomethylation of activated arenes.

For the practical application of organic light emitting devices (OLEDs) based on thermally activated delayed fluorescence (TADF) for large area TV and solid state lighting, low power consumption as well as the operation lifetime at high brightness over 1000 cd m-2 must be improved. Here, we have developed a novel hexaphenylbenzene-based sterically bulky hole-transport layer named 4DBTHPB with deep ionization potential of 5.8 eV and high triplet energy of 2.7 eV. By using 4DBTHPB, we can realize a highly efficient and stable TADF OLED exhibiting external quantum efficiency of 21.6 % and power efficiency of 54.3 lm W-1 and operation lifetime at 50 % (LT50 ) of approximately 10 000 h at an initial luminance of 1000 cd m-2 . These performances are comparable to those of the state-of-the-art green phosphorescent OLEDs reported in the scientific literatures.

Hexa-peri-hexabenzocoronene (HBC)-based donor-acceptor dyads were synthesized with three different acceptor units, through two pathways: 1) "pre-functionalization" of monobromo-substituted hexaphenylbenzene prior to the cyclodehydrogenation; and 2) "post-functionalization" of monobromo-substituted HBC after the cyclodehydrogenation. The HBC-acceptor dyads demonstrated varying degrees of intramolecular charge-transfer interactions, depending on the attached acceptor units, which allowed tuning of their photophysical and optoelectronic properties, including the energy gaps. The two synthetic pathways described here can be complementary and potentially be applied for the synthesis of nanographene-acceptor dyads with larger aromatic cores, including one-dimensionally extended graphene nanoribbons.

With propeller-like shape, hexaphenylbenzene bromides display different recognition abilities for guest molecules in solid state. HBH can encapsulate CH2Cl2 or Et2O molecules selectively from different solvent systems. For DBH, the recognition pattern is dominated between themselves. In CH2Cl2/toluene/Et2O system, toluene molecule can be encapsulated selectively by MBH. In these supramolecular assemblies, bromine bonding plays an important role.

The longitudinal extension of cycloparaphenylenes (CPP) towards ultrashort carbon nanotubes (CNTs) is essential for the solution based bottom-up synthesis of CNTs. Herein, the longitudinal extension of the CPP skeleton by the introduction of hexaphenylbenzene units towards polyarylated [n]CPPs is described. Further, the applicability of the Scholl reaction to selectively form graphenic sidewalls is demonstrated. The ring size and substitution patterns of the polyarylated [n]CPPs were varied to overcome strain-induced side reactions during the oxidative cyclodehydrogenation and cyclic para-hexa-peri-hexabenzocoronene trimers ([3]CHBCs) were selectively obtained. This concept is envisioned as an access to ultrashort carbon nanotubes subject to the condition that further benzene rings with the right connectivity will be inserted.

In this work, two rigid, multiple tetraphenylethene (TPE)-substituted, π-conjugated, snowflake-shaped luminophores BT and BPT were facilely synthesized by using a 6-fold Suzuki coupling reaction. These molecules are constructed based on the nonplanar structure of propeller-shaped hexaphenylbenzene (HPB) or benzene as core groups and TPE as end groups. As a result, they reserve the intrinsic aggregation-induced emission (AIE) property of the TPE moiety. Meanwhile, both fluorescence quantum yield and piezochromic behavior in the solid state can be tuned or switched by inserting the phenyl bridges through changing the twisting conformation. The more extended structure BPT showed a much stronger AIE effect and higher ΦF,f in the solid state in comparison with that of BT. Furthermore, an excellent optical waveguide application of these molecules was achieved. However, the revisable piezofluorochromic behavior has only appeared when BT was ground using a pestle and treated with solvent.

A series of nonplanar tetraphenylethene (TPE)-hexaphenylbenzene (HPB) adducts was designed and synthesized by Diels-Alder reaction of the acetylene precursors and tetraphenylcyclopentadienone. All of the adducts showed aggregation-induced emission features. The twisting amplitude and steric hindrance of the TPE and HPB units were found to play a crucial role in their fluorescence behaviors in the aggregated state.

The easily rotatable peripheral aromatic rings around central benzene in hexaarylbenzene (HAB) derivatives create a very intriguing nonplanar, propeller-shaped geometry. Because of the very low susceptibility toward self-aggregation, HAB derivatives are much stronger candidates among various polyphenylenes/hetero-oligophenylenes when poor molecular cohesion and inefficient packing is required. However, the native properties of hexaphenylbenzene (HPB) can be varied by proper tailoring and substitution of the HAB core. The cohesion and packing in the structures of HAB aggregates induce effective structural variations so as to modify the fundamental features. Recently, HAB derivatives attracted a lot of research interest because of their significant role as liquid crystalline materials, organic light-emitting diodes, photochemical switches, redox materials, and molecular receptors. Herein, detailed attention is given to the pioneering work based on synthetic optimization of different HAB cores, elaborated st...

Go to three dimensions: as a step toward a bottom-up synthesis of size-defined carbon nanotubes (CNTs), [3]cyclo-4',4''''-hexaphenylbenzenes ([3]CHPBs) were synthesized and investigated. Theoretical and experimental results revealed that [3]CHPBs possess highly twisted [9]cyclo-p-phenylene cores. [3]cyclo-2,11-(Hexa-peri-hexabenzocoronene) ([3]CHBC) was also examined for CNT synthesis.

A new and facile method for the preparation of mono- and hexa-functional Ni-bipyridyl-based initiators that mediate Kumada polycondensation of 2 -bromo- 5 -chloromagnesio- 3 -hexylthiophene into head-to-tail regioregular poly(3-hexylthiophene), P 3 HT, has been developed. An important advantage of the catalytic system presented herein is the ease of the preparation of a number of Ar-Nibipy-Br initiators from readily available aryl halides. As an example, the "core-first" synthesis of 6-arm star-like P 3 HT having a hexaphenylbenzene core is demonstrated.

The synthesis and properties of the first examples of dendritic multiblock coPESs, bearing sulfonated dendritic clusters, that form strong membranes are described. End-capped dendritic multiblock coPESs with various average block lengths (n = 50―80) were synthesized by two-step reactions. The synthesis of dendritic blocks consisting of difunctional dendritic block and monofunctional dendritic end-group was accomplished by an aromatic nucleophilic substitution reaction of hexakis(4-(4-fluorophenylsulfonyl)phenyl)benzene with varying amounts of 1-(4-hydroxyphenyl)-2,3,4,5,6-pentaphenylbenzene, which provides a number of pendant phenyl rings as postsulfonation sites. Polycondensation of a controlled molar ratio between 4,4'-dihydroxybenzophenone and bis(4-fluorophenyl)sulfone monomers was carried out in the presence of the difunctional and monofunctional dendritic blocks in sulfolane at 215 °C for 3.5 h. Essentially six sulfonic acid groups were introduced into each hexaphenylbenzene moiety on the dendritic blocks by reaction with a large excess of chlorosulfonic acid, followed by hydrolysis with KOH aqueous solution. The introduction of longer average blocks (n = 60―80) into the dendritic PESs improved the mechanical properties of the resulting sulfonated dendritic PES membranes. At a level of IEC (0.92―1.26 meq/g) similar to Nafion (0.91 meq/g), PES membranes showed proton conductivities (58―67 mS/cm) comparable with that of Nafion (99 mS/ cm).

Hexaphenylbenzene derivatives bearing two aldehyde groups were prepared by reaction of 4,4′-(ethyne-1,2-diyl)dibenzaldehyde with bisarylalkynes in the presence of a catalytic amount of Co2(CO)8. These synthetic intermediates were used to produce the corresponding bismalonates. Finally, macrocyclization of the bismalonates with C60 afforded equatorial fullerene bisadducts. The relative position of the two cyclopropane rings on the C60 core was determined on the basis of the molecular symmetry (C1) deduced from the 1H and 13C NMR spectra and further confirmed by the characteristic features seen in their UV/Vis spectra.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

We have reported the template synthesis of a 90-membered macrocycle by olefin metathesis. The macrocycle 7 was prepared by an initial six-oxidative-addition reaction of 2 by [Pt(PEt(3))(4)]. The definite structure of a six-oxidative product was confirmed by the crystal structure. The coordination of 2,6-bis(hex-5-enyloxy)pyridine to 3 led to the hexacationic aryl complex of type 4. The metathesis of olefin-substituted pyridine with Grubbs catalyst ([PhCH==RuCl(2)(Cy(3)P)(2)]) formed the expected macrocycle 5. The olefin metathesis reaction was formed under high dilution to suppress intermolecular olefin metathesis polymerization. The detachment of the newly formed macrocycle 6, followed by reduction to alkane macrocycle 7 by using palladium on charcoal and hydrogen led to a huge macrocycle. The mild and easy access of the template protocol opens a host of potential subsequent transformations toward the construction of a variety of macrocycles.

The intramolecular spin–spin interaction in the highly oxidized species of a star-shaped oligoarylamine, namely hexakis{4-[bis(p-methoxyphenyl)amino]phenyl}benzene (1), in which six diphenylamine units are introduced as redox-active sites into a central hexaphenylbenzene core, has been investigated by EPR spectroscopy. The hexacation-rich sample was prepared by chemical oxidation with 7.5 equivalents. of [bis(trifluoroacetoxy)iodo]benzene (PIFA) in the presence of 10 vol.-% trifluoroacetic acid (TFA) in dichloromethane at 195 K. Variable-temperature EPR measurements provided the non-Curie temperature dependence of the signal intensity. The fine structure of the EPR spectrum also varies with temperature. In order to identify the spin multiplicity of the generated poly(radical cation), we carried out electron spin transient nutation (ESTN) measurements based on pulsed EPR spectroscopy at various temperatures. From the ESTN spectra, it was found that the high-spin states are thermally populated with increasing temperature. These results indicate the low-spin ground state of the poly(radical cation) of 1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Two novel star molecules functionalized with 7-azaindolyl and 2,2'-dipyridylamino groups have been synthesized. Both molecules possess a sixfold rotation symmetry. Molecule L1 is based on the hexaphenylbenzene core with the formula of hexa[p-(7-azaindolyl)phenyl]benzene, while molecule L2 is based on the hexakis(biphenyl)benzene core with the formula of hexa[p-(2,2'-dipyridylamino)biphenyl]benzene. Both compounds have been characterized by single-crystal X-ray diffraction analyses. Molecule L1 forms extended two-dimensional layered structure, while L2 forms interpenetrating columnar stacks in the solid state, as revealed by X-ray diffraction analyses. Nanowire structures based on columnar stacks through self-assembly of L2 on a graphite surface were revealed by an STM study. Molecules L1 and L2 are capable of binding to metal ions, resulting in unusual structural motifs. Two Ag(I) complexes with the formulae of [(AgNO(3))(2)(L1)] (1) and [(AgNO(3))(3)(L1)] (2) were isolated from the reactions of AgNO(3) with L1. Compound 1 displays extended intermolecular pi-pi stacking interactions that are responsible for its extended two-dimensional structure in the crystal lattice. Complex 2 has a "bowl" shape and forms polar stacks in the crystal lattice. A Cu(II) complex with the formula of [{Cu(NO(3))(2)}(6)(L 2)] (3) was isolated from the reaction of Cu(NO(3))(2) with compound L2. The six Cu(II) ions in 3 are chelated by the 2,2'-dipyridylamino groups of the star ligand L2. Intermolecular Cu-O (nitrate) bonds lead to the formation of an extended two-dimensional coordination network of 3. Both L1 and L2 are blue luminescent. Their interactions with Ag(I) or Cu(II) cause drastic quenching of emission. In addition, the luminescence of L1 and L2 is sensitive to the presence of protons, which cause a reduction of emission intensity and a red shift of the emission energy.

Attractive materials for molecular electronics are the polycyclic aromatic hydrocarbons (PAHs), the hydrogen-terminated segments of a graphitic plane. Since the processing of larger PAHs, for example hexa-peri-hexabenzocoronene, is complicated by their extremely low solubilities and very small vapor pressures, the possibility of a surface-assisted synthesis of planar PAHs is investigated starting from diphenylacetylene (left) and hexaphenylbenzene (right), as shown in the picture.

The deposition of polycyclic aromatic hydrocarbons on substrate surfaces is a key step for using such disklike molecules in nanoelectronic devices. An alternative to the (frequently problematic) preparation by evaporation or deposition from solution is to use the substrate surface as a template for the planarization that accompanies the cyclodehydrogenation (see picture).

Partly solvent-separated and partly solvent-shared, the contact ion triple of the 9,10-diphenyltetrabenz[a,c,h,j]anthracene dianion is formed by the ultrasonically activated reaction of hexaphenylbenzene with lithium metal powder in 1,2-dimethoxyethane (dme) [Eq. (1)]. The proposed microscopic pathway for this reaction-twofold dehydrogenation and C-C bond formation-is supported by quantum-chemical calculations.

The syntheses of four hexabenzo[bc,ef,hi,kl,no,qr]coronene (HBC) derivatives have been carried out. Double Knoevenagel condensation of the benzil 5 with the ketone 6 gave the 2,3,4,5-tetrakis(4-tert-butylphenyl)cyclopenta-2,4-dien-1-one (7). Diels-Alder addition of 7 with di(4-tert-butylphenyl)acetylene, 4-[(4-tert-butylphenyl)ethynyl]-1,1′-biphenyl (9) or 1-tert-butyl-4-(phenylethynyl)benzene (11) gave the substituted hexaphenylbenzene 8, 10 and 12 which were cyclodehydrogenated to yield 1, 2 and 3, respectively. Similarly, condensation of 5 with dibenzylketone yielded the cyclopentadienone 13 which gave, by cycloaddition with di-(4-tert-butylphenyl)acetylene, the tetrasubstituted hexaphenylbenzene 14 which was cyclodehydrogenated to furnish 4.

The cover picture shows a sun-shaped hexaphenylbenzene unit shining over the equator of a fullerene spheroid. This macrocyclic fullerene bisadduct with an equatorial addition pattern was obtained with excellent regioselectivity from the reaction of C60 with a bismalonate constructed on a hexaphenylbenzene scaffold. Details are discussed in the article by J.-F. Nierengarten et al. on p. 3879 ff.

By treating Ti(η6-toluene)[(μ-X)2(AlX2)]2 (X = Cl: 1a, X = Br 1b) with C2R2 (R = Me, Ph) tetraorganylcyclobutadiene complexes of formula Ti(η4-C4R4)[(μ-X)2(AlX2)]2 (R = Ph, X = Cl: 2a, X = Br: 2b; R = Me, X = Br: 3b) have been obtained in good yields. Compound 2b has been studied by X-ray diffraction methods. The titanium atom possesses an approximate square pyramidal coordination, the apical position being occupied by the symmetrically bonded tetraphenylcyclobutadiene ring, the four bridging bromides to the two AlBr2 groups forming the base of the pyramid, 0.99 A away from the titanium atom. The tetrabromoaluminato moiety of 2b can be substituted by carbocyclic anionic ligands, such as Cp and COT, and the corresponding complexes 4 and Ti(η4-C4Ph4)(COT) were obtained. The spectroscopic study of the Ti(η6-benzene)[(μ-X)2(AlX2)]2/diphenylacetylene (DPA) system (X = Cl: 5a, X = Br: 5b) has revealed the existence of three products, corresponding to the 1:1, 1:2, and 1:3 molar ratios. The possible role of the known AlX3 · C4R4 complexes in this reaction is discussed. The cyclotrimerization reactions of substituted acetylenes in the presence of η6-arenetitanium(II) complexes as precursors have been studied. In toluene or methylcyclohexane Ti(η6-toluene)[(μ-Br)2(AlBr2)]2 was found to catalyze the formation of alkyl-substituted aromatic hydrocarbons from 2-butyne, phenylacetylene, and 1-hexyne at about 80°C over 15 h with turnovers (moles of converted alkyne per mole of titanium) of about 520, 900, and 990, respectively. The cyclooligomerization of DPA in the presence of Ti(η6-benzene)[(μ-X)2(AlX2)]2 (X = Cl, Br) was studied in detail. The activity of the chloro derivative 5a is higher than that of the bromide catalytic precursor 5b. In addition to hexaphenylbenzene and octaphenylcyclooctatetraene, other oligomerization by-products (triphenylethylene, 1,1,2,2-tetraphenylethane, 1,2,3-triphenylnaphthalene, and 1,2,3-triphenylazulene) were observed, whose formation was drastically reduced in the presence of alkyl aluminium halides. Reaktivitat von Titan(II)-Aren-Derivaten mit substituierten Alkinen. Cyclooligomerisations-Reaktionen und Kristall- und Molekulstruktur von [η4-C4(C6H5)4]Ti[(μ-Br)2(AlBr2)]2 Durch Umsetzung von Ti(η6-toluene)[(μ-X)2(AlX2)]2 (X = Cl: 1a, X = Br 1b) with C2R2 (R = Me, Ph) wurden Tetraorganylcyclobutadien-Komplexe der Zusammensetzung Ti(η4-C4R4)[(μ-X)2(AlX2)]2 (R = Ph, X = Cl: 2a, X = Br: 2b; R = Me, X = Br: 3b) in guten Ausbeuten erhalten. Verbindung 2b wurde mit Rontgenbeugungsmethoden untersucht. Das Titan-Atom ist naherungsweise quadratisch-pyramidal koordiniert, wobei die apikale Position von dem symmetrisch gebundenen Tetraphenylcyclobutadien-Ring eingenommen wird und die vier zu den AlBr2-Gruppen verbruckenden Brom-Atome die 0.99 A vom Titan-Atom entfernte Basisflache der Pyramide bilden. Die Tetrabromoaluminat-Gruppe in 2b kann durch carbocyclische anionische Liganden wie Cp und COT ersetzt werden, wobei die entsprechenden Komplexe 4 und Ti(η4-C4Ph4)(COT) erhalten wurden. Die spektroskopische Untersuchung des Systems Ti(η6-benzol)-[(μ-X)2(AlX2)]2/diphenylacetylen (DPA) (X = Cl: 5a, X = Br: 5b) erbrachte den Nachweis dreier den molaren Verhaltnissen von 1:1, 1:2 und 1:3 entsprechender Produkte. Die mogliche Rolle des AlX3 · C4R4-Komplexes in dieser Reaktion wird diskutiert. Die Cyclotrimerisierungsreaktionen von substituiertem Acetylen in Gegenwart von η6-Aren-Titan(II)-Komplexen als Vorstufen wurden untersucht. Es zeigte sich, das Ti(η6-toluol)[(μ-Br)2(AlBr2)]2 in Toluol oder Methylcyclohexan bei ca. 80°C im Verlaufe von 15 h die Bildung von Alkyl-substituierten aromatischen Kohlenwasserstoffen aus 2-Butin, Phenylacetylen und 1-Hexin mit einem Umsatz (mol abreagierendes Alkin pro mol Titan) von 600, 900 bzw. 990 katalysiert. Die Cyclooligomerisierung von DPA in Gegenwart von Ti(η6-benzol)[(μ-X)2(AlX2)]2 (X = Cl, Br) wurde ausfuhrlich untersucht. Die Aktivitat des Chloro-Derivats 5a ubersteigt die der Bromo-Katalysator-Vorstufe 5b. Auser Hexaphenylbenzol und Octaphenylcyclooctatetraen wurden weitere Nebenprodukte der Oligomerisierung beobachtet (Triphenylethen, 1,1,2,2-tetraphenylethan, 1,2,3-Triphenylnaphthalin und 1,2,3-Triphenylazulen), deren Bildung in Gegenwart von Alkylaluminiumhalogeniden deutlich verringert war.

The 1H NMR spectrum of hexakis(3-methoxyphenyl)benzene exhibits a methoxy absorption which looks exactly like a triplet. The spacing between the signals is, however, proportional to rather than independent of the field strength. The aryl H-5 region of this compound and the methyl region of hexakis(3-methylphenyl)benzene display similar field-proportional, triplet-like splittings. This property of meta-substituted hexaphenylbenzenes cannot be explained by either preferential or residual isomerism, even in the presence of many accidental isochronies. A chemical shift model based on the hypothesis that the meta substituents do not disturb the geometry of the hexaphenylbenzene skeleton or the populations of the rotamers explains the spectra in a straightforward manner.

The synthesis of hexabenz-1,12;2,3;4,5;6,7;8,9;10,11-coronene, using two different reaction schemes is described. The cyclodehydrogenation of hexaphenylbenzene, and the reaction of dibenz-1,9;2,3-anthrone with Zn/ZnCl2 lead to identical products, the chemical and crystallographic properties of which demonstrate the structure of hexabenzcoronene. Furthermore, two other hydrocarbons have been isolated from the reaction of dibenzanthrone with Zn/ZnCl2. The UV. spectrum of the first, and its cyclization to hexabenzcoronene show that it is tetrabenz-4,5;6,7;11,12;13,14-peropyrene. The properties of the second indicate that it is tetrabenz-1,2;3,4,8;9; 10,11-bisanthene.