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Toxic volatile organic compounds (VOCs) including benzene and toluene that are emitted from industrial chemical processes and outdoor or indoor chemical applications are harmful to the environment and threaten human health. Porous organic polymers (POPs), which have attracted much interest during the last decade as materials for gas adsorption and separation, have only recently gained attention for the adsorption of VOCs. We synthesised two POPs based on hexaphenylbenzene (HEX-POP-93) and hexabenzocoronene (HBC-POP-98) and studied the adsorption of organic vapours. Interestingly, while both POPs have moderate BET surface areas (687 and 548 m2 g−1 respectively), they both show an excellent affinity for organic vapours over water, with a high benzene adsorption capacity of 99.9 wt% for HEX-POP-93.

The hydrogenation of hexaphenylbenzene was studied, affording novel partially hydrogenated hexacyclohexylbenzene (

A sharp difference in the change in the molar volume during the transition from the solid phase to the solution for a number of 2D molecules of reagents compared with 3D molecules of the Diels-Alder reaction adducts was observed. The dissolution of 2D crystal molecules is accompanied by a significant increase in volume (10–15%) with a dissolution enthalpy close in magnitude to the fusion enthalpy. A similar transition for 3D crystal molecules is often accompanied by an unexpected decrease in volume and even negative enthalpy of dissolution in inert solvents. The similar change in these parameters is also considered for a number of 3D molecules: 1,3,5-triphenylbenzene, hexaphenylbenzene, 9,10-diphenylanthracene, congressane, and C-60 fullerene. This can be explained by the fact that the surface of large 3D molecules in a solution can be much more thoroughly surrounded by solvent molecules than in its own environment. These results indicate that the values of activation and reaction volumes and their ratio (ΔV≠S/ΔVr-n, S) may be weakly related to the mechanism of non-polar cycloaddition reactions.

By introducing six triarylamine groups to a hexaphenylbenzene (HPB) or a hexakis(2-thienyl)benzene (HTB) core, two propeller-shaped, triarylamine-rich, and low-cost hole-transporting materials (HTMs), which are termed as HPB-OMe and HTB-OMe, respectively, with considerable hole mobility, were obtained by easy synthetic routes. Solid-state planar perovskite CH3NH3PbI3 solar cells (PSCs) with two new HTMs showed high power conversion efficiencies (12.9% for HPB-OMe and 17.3% for HTB-OMe in forward scans) under standard 100 mW cm–2 AM 1.5G illumination without doping. A comparison of matched-degree of energy levels, hole-transporting ability, photovoltaic conversion efficiencies, and recombination of the two HTMs indicated that developing multi-triarylamine- and thiophene-rich molecules provides candidate and efficient dopant-free HTMs for PSCs.

AIE as a photo-physical phenomenon is growing at an exponential rate which provides unique opportunities in different scientific domains. Inspired from fascinating properties of AIE-based conventional frameworks like tetraphenylethylene (TPE), hexaphenylsilole (HPS), new motifs, and their aggregation properties have been rationalized rapidly. In this chapter, the current aspects of AIE-based self-assembled probes using novel frameworks like hexaphenylbenzene (HPB), hexaarylbenzene (HAB), pentacenequinone, pyrazine, and terphenyl are documented. Further, the applications of these probes in chemo/biosensing are presented with emphasis on our current reports.

Helicenes are inherently chiral polycyclic aromatic molecules. Laterally extended helicenes have their outer rim extended by one or more aromatic rings, which gives them unique optical and electron properties and makes them hot candidates for applications in asymmetric catalysis or molecular electronics, for instance. However, the larger the outer rim is, the more difficult the synthesis of wide helicenes becomes. Frequently bad solubility of laterally extended helicenes, as well as their intermediates, requires comprehensive optimisation of the reaction conditions, which are commonly used in helicene synthesis. In my Bachelor Thesis, I focus on synthesis of a laterally extended helicene with two hexabenzocoronene moieties incorporated in its structure. One of the essential intermediates, bromoiodohexaphenylbenzene derivative, was prepared by Diels-Alder reaction. Optimised conditions of this reaction enabled the synthesis of crucial intermediates necessary for further steps in the target helicene synthesis. Key words: helicene, hexabenzocoronene, hexaphenylbenzene, Diels-Alder, polyaromatics

In an attempt to establish the structures of the product formed in the reaction of PdCl2 and diphenylacetylene in polar organic solvents, the reactions were carried out in alcohols, acetonitrile and tetrahydrofuran at room temperature. The reactions in protic solvents such as primary and secondary alcohols resulted in the cyclic dimerization of diphenylacetylene to yield the corresponding dimeric endo-4-alkoxy-pi-1,2,3,4-tetraphenylcyclobutenypalladium(II) chloride complexes 1-4 in good yields. In these complexes the tetraphenylcyclobutenyl moieties are coordinated to palladium atoms in eta(3)-mode and are bridged by two chlorides as confirmed by the single crystal X-ray analysis of complexes 1, 2 and 4. In all these complexes, the coordination of cyclobutenyl moieties to palladium atoms are similar but a marked difference was observed for the Pd2Cl2 core which is planar in complex 1 but puckered in complexes 2 and 4 resulting in shorter PdPd distances. The same reaction under solvent free ball milling condition yielded hexaphenylbenzene by the cyclic trimerization while that in the presence of ethanol and n-butanol produced complexes 1 and 3, respectively, as major and hexaphenylbenzene as minor product. An efficient catalytic synthesis of hexaphenylbenzene using PdCl2 was developed using ball milling condition which has several advantages over the existing catalytic systems.

In the present work, we report the fabrication of regular coronene (COR) clusters on surfaces in ambient conditions in the two-dimensional network formed by hexaphenylbenzene derivatives (HPB) via structural transformation. HPB could form a stable snowflake network structure on the highly oriented pyrolytic graphite surface at the air-solid interface. When COR molecules were introduced into the system, the HPB snowflake network could transform to honeycomb structures, and the COR heptamers were subsequently aggregated and entrapped into the cavity. Scanning tunneling microscopic was employed to monitor the assembly behavior of both HPB and HPB/COR at a submolecule scale level, and density functional theory calculations were utilized to reveal that the structural transformation and the entrapment are the energetically favorable. The pores formed from HPB might also give a clue to immobilizing some functional molecule clusters, like COR, to fabricate their ordered monolayer in ambient conditions, so as to obtain complex supramolecular surface structures.

A hexaphenylbenzene (HPB)-based derivative bearing thiol groups has been designed and synthesized that undergoes aggregation-induced emission enhancement in mixed aqueous media to form rodlike fluorescent aggregates. These rodlike aggregates behave as a "not quenched" probe for the detection of silver ions and further act as reactors and stabilizers for reducing-agent-free preparation of blue luminescent silver nanoclusters at room temperature. The utilization of fluorescent supramolecular aggregates for the preparation of Ag NCs in mixed aqueous media is unprecedented in the literature. Moreover, the wet chemical method that we are reporting in the present paper for the preparation of luminescent silver nanoclusters is better than the other methods reported in the literature. Further, these in situ generated Ag NCs showed exceptional catalytic activity in the preparation of pyrroles involving cocyclization of isocyanides and terminal alkynes. Interestingly, the catalytic efficiency of in situ generated Ag NCs was found to be better than the other catalytic systems reported in the literature.

Three new emitting compounds of 5P-VCB, 5P-VAn and 5P-VPy for OLED based on hexaphenylbenzene moiety were synthesized. Physical properties by the change of the substitution groups of the synthesized materials were systematically examined. Photoluminescence spectrum of the synthesized materials showed maximum emitting wavelengths of about 420∼487 nm in solution state and 452∼488 nm in film state, indicating blue emission color. OLED devices were fabricated by the synthesized compounds using vacuum deposition process as an emitting layer. Current efficiencies and CIE values of 5P-VCB, 5P-VAn and 5P-VPy were 1.76, 0.38 and 7.91 cd/A and (0.15, 0.07), (0.20, 0.31) and (0.20, 0.36), respectively.

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 rhodamine appended hexaphenylbenzene based derivative 5 has been designed and synthesized, which displays through bond energy transfer in the presence of picric acid in MeOH and serves as “turn on” sensor for picric acid. Furthermore, derivative 5 exhibits an intense colorimetric response towards picric acid and can selectively detect picric acid with a detection limit of 104.9 pg cm−2.

Supramolecular aggregates of hexaphenylbenzene derivative 2 exhibit aggregation induced emission enhancement and modulation of self-assembled architecture from spherical to flower-like assembly in the presence of H2S. Furthermore, probe 2 displays higher photostability, low toxicity and bright green fluorescence in two-photon microscopy (TPM) imaging for the detection of H2S in live HeLa cells.

The synthesis of π-extended [12]cycloparaphenylene (CPP) derivatives from a kinked triangular macrocycle is presented. Depending on the reaction conditions for reductive aromatization, either a hexaphenylbenzene cyclohexamer or its C2-symmetric congener was obtained. Their structures were confirmed by NMR spectroscopy or X-ray crystallographic analysis. With the support of DFT calculations, a mechanistic explanation for the unexpected formation of the oval shaped bis(cyclohexadiene)-bridged C2-symmetric macrocycle is provided. The here employed congested hexaphenylbenzene mode of connectivity in conjunction with a non-strained precursor improves oxidative cyclodehydrogenation toward the formation of ultrashort carbon nanotubes (CNT)s. Thus, this strategy can pave the way for new conceptual approaches of a solution-based bottom-up synthesis of CNTs.

In recent years, low-bandgap polymers have attracted a wide range of attention in many fields. These compounds syntheses were focused on three factors according to the Roncali bandgap theory: 1) the degree of bond length alternation Eδr, 2) the aromatic resonance energy of the cycle ERes, and 3) the substituted groups ESub. Now, we designed and prepared the low-bandgap polymers in a different way by the factor Eθ, the polymer chain deviation from planarity, and EInt, the interaction of the molecular chains in the solid state. So, three polycyclic aromatic hydrocarbons with different space-constructions based on the hexaphenylbenzene derivatives were prepared in this work: linear type (P1-OX), V type (P2-OX) and zigzag type (P3-OX). These well-defined polymers exhibited the interesting behaviors in optics, electrochemistry due to their different extent of planarity. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) gave the incremental orderly molecular weight distributions of P1, P2 and P3, whose weight-average molecular weights by gel permeation chromatography were 9000, 5500 and 69000, respectively. Their lamellar layer structures and pi-pi intermolecular stacking were demonstrated by two-dimensional grazing-incidence X-ray diffraction (2D-GIXRD), showing the edge-on chain conformation. At last, the materials were perfectly adopted to fabricate the high-performance organic field-effect transistor (OFET) devices, which revealed that these compounds would possess a great prospect as semiconductors.

Aromatic polyimides (PIs) with a hexaphenylbenzene unit were synthesized from 1,4-bis[4-(4-aminophenoxy)phenyl]-2,3,5,6-tetraphenylbenzene (1) and various tetracarboxylic dianhydrides by a conventional two-step procedure that included ring-opening polymerization in N-methyl-2-pyrrolidone and subsequent thermal cyclic dehydration. The PIs were characterized by X-ray diffraction, differential scanning calorimetry, thermogravimetry, and dynamic mechanical analysis. The PIs had glass transition temperatures in the range of 289–352°C, and all the polymers were amorphous. The structure–property relationships of these PIs were examined and compared with those of the previously prepared analogous PIs from 4,4′-bis(4-aminophenoxy)biphenyl (2) and 4,4′-bis(4-amino-2-phenylphenoxy)biphenyl (3). Water absorption and dielectric constants of the PIs were also compared and discussed on the basis of imide content per repeating unit.

Herein we report a series of porous organic polymers (POPs) synthesized through a Sonogashira cross-coupling reaction containing hexaphenylbenzene (HEX) and hexabenzocoronene (HBC) with varying peripheral substitution. We observed vastly different gas sorption properties depending on substituent size and the extent of conjugation in the monomer core structure with BET surface areas ranging from 320 m2/g for HBC-POP-4 to 1140 m2/g for HEX-POP-3. In order to more clearly understand the effects of functional group substitution on the properties of these materials, we have characterized these POPs using N2, CO2, and H2 sorption measurements, powder X-ray diffraction, FT-IR spectroscopy, TGA, and EDX.

The synthesis and characterization of a series of novel hexaphenylbenzene (HPB) based polymers of intrinsic microporosity (PIM-HPBs) containing methyl, bromine, and nitrile substituents are reported. The successful formation of thin films from these polymers allowed the evaluation of the influence of the substituents on intrinsic microporosity and gas permeability. Analysis by the time-lag method also yielded information about gas diffusion coefficients and, indirectly, the gas solubility. The gas permeability varies as a function of the polarity of the substituents and shows a significant increase after treatment of the samples with methanol, especially for films cast from THF as the solvent. This enhancement, which is mostly due to an increase in the diffusion coefficient, is only partially lost upon aging of the membranes for 5 months. Measurements at different feed pressures confirm the typical dual mode sorption behavior, with increasing diffusivity and decreasing permeability and solubility as a function of the feed pressure.

The transport of the lithium ions is the basis of lithium ion conductivity of currently used electrolytes. Understanding how the transport of lithium ions within the matrix is influenced by the interactions with solvating moieties is needed to improve their performance. Along these lines well-defined model compounds based on cyclotriphosphazene (CTP) and hexaphenylbenzene (HPB) cores, bearing side groups of ethylene carbonate, a common solvent for lithium salts used as electrolytes in Li-ion batteries (Thielen et al. Chem. Mater, 23, 2120, 2011) and blended with different amounts of Lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) have been studied by multinuclear nuclear magnetic resonance (NMR) spectroscopy. The local dynamics of the matrix was probed by 1H and 31P NMR, while the local dynamics of the Li+ cations was unraveled by 7Li and 13C NMR. Transport of both ions was studied by pulsed-field gradient (PFG) NMR. Based on the different temperature dependences of the dynamics the bulk ion transport is not attributed to local dynamics, but to translational diffusion best characterized by PFG NMR. Although the glass transition temperatures of the blends are low, their conductivities are only in the range of typical polymer electrolytes. The results of NMR spectroscopy are in accord with the conjecture that the coordination between the cyclic carbonate functionality and the Li+-ion is too tight to allow for fast ion dynamics.

Three new hexaphenylbenzene end-capped tri(p-phenylenevinylenes) were synthesized by the Horner–Wadsworth–Emmons reaction in good yields (86–76%). All compounds have bright fluorescent emissions in the blue to blue–green region in solution (λmax = 445–492 nm in tetrahydrofuran) and also high emission efficiency (Φfl = 0.51–0.72 in tetrahydrofuran). They exhibit good electrochemical reversibility, high thermal stability, and have high HOMO value.

A hexaphenylbenzene-based receptor 3 has been synthesized that forms a fluorescent spherical aggregate in mixed aqueous media due to its aggregation-induced emission enhancement attributes. These fluorescent spherical aggregates show ratiometric response toward cyanide ions via nucleophilic addition and undergo deaggregation to form smaller nanoaggregates. In addition, the solution-coated paper strips of 3 can detect cyanide ions in the range of ∼2.6 ng/cm(2), thus, providing a simple, portable, and low-cost method for detection of cyanide ions in aqueous media. Receptor 3 also behaves as a set-reset memorized sequential logic circuit with chemical inputs of CN(-) ions and trifluoroacetic acid or H(+) (pH ≤ 3).

The propeller-like nonplanar building unit containing poly(aryl ether ketone)s were synthesized from 1,2-bis(4-hydroxyphenyl)-3,4,5,6-tetraphenyl-benzene (BHPTPB) and bis(4-fluorophenyl) sulfone with bis(4-hydroxydiphenyl) sulfone in NMP. New structures and/or morphologies for existing materials need to be considered in case if increased benefits are desired. The sulfonation was taken selectively on hydrophilic block segment as well as para position of the pendent phenyl groups with concentrated sulfuric acid. The stoichiometry mole ratios were changed with hydrophilic blocks of 12, 15, 17, 20, and 23 mol% of BHPTPB monomer to control the ion exchange capacity. The structural properties of polymer membranes (HP-12, 15, 17, 20, and 23) were studied by FT-IR, 1H NMR spectroscopy, thermogravimetric analysis (TGA), and atomic force microscope (AFM). The water uptakes were 8.1–69.4% at 75 °C with changing the ion exchange capacities. The resulted proton conductivities were 66.58–103.73 mS/cm at 80 °C with 90% relative humidity. The highest power density of a fuel cell using HP-23 and Nafion 211 was 0.47 and 0.45 W/cm2, respectively, at 0.6 V.

We report a practical synthetic protocol and mechanistic details for the selective alternate derivatization of the hexaphenylbenzene (HPB) framework through a thermodynamically controlled halogen dance. The stability of the alternately trilithiated species of HPB is interpreted by the through-space interaction at the ipso-carbons of the phenyl groups of the HPB framework. By using this approach, C3-symmetric and lower-symmetric HPB derivatives possessing two or three kinds of substituents on the periphery have become easily and practically available.

Template-assembled synthetic proteins (TASPs) synthesized from rigid templates have attracted attention due to their interesting structural architectures and potential biomedical applications. Herein, we report the design, synthesis and characterizations of TASPs based on hexaphenylbenzene template (HPB) having twelve peptide attachable axial-arms in its structure. The peptides were attached to all the axial-arms of the template in a single step using simple solution phase peptide coupling strategy. The reaction conditions were standardized systematically using simple amines from smaller size to larger ones.

Poly (ether sulfone) membranes (PHP) were prepared with 25 mol% of 1,2-bis (4-hydroxybenzene)-3,4,5,6-tetraphenylbenzene (BHPTPB). BHPTPB has a conjugated propeller-like nonplanar conformation structure containing the peripheral seven aromatic rings which facilitate the formation of π-π interactions. A series of sulfonated poly (ethersulfone) s (SHP 25) was synthesized with concentrated sulfuric acid. The sulfonation took place selectively on the multiphenyl unit, and simultaneously on the side-chain phenyl groups. Composite membranes were prepared with copolymers and SiO2nanoparticles (20 nm, 4~10%wt). The composite membranes were cast from DMSO. A series of composite membranes structures and characteristic were evaluated by the1H-NMR spectroscopy, and thermal stabilities. The membranes were performed by ion exchange capacity (IEC), water uptake and proton conductivity.

Free-standing nanomembranes with molecular or atomic thickness are currently explored for separation technologies, electronics, and sensing. Their engineering with well-defined structural and functional properties is a challenge for materials research. Here we present a broadly applicable scheme to create mechanically stable carbon nanomembranes (CNMs) with a thickness of similar to 0.5 to similar to 3 nm. Monolayers of polyaromatic molecules (oligophenyls, hexaphenylbenzene, and polycyclic aromatic hydrocarbons) were assembled and exposed to electrons that cross-link them into CNMs; subsequent pyrolysis converts the CNMs into graphene sheets. In this transformation the thickness, porosity, and surface functionality of the nanomembranes are determined by the monolayers, and structural and functional features are passed on from the molecules through their monolayers to the CNMs and finally on to the graphene. Our procedure is scalable to large areas and allows the engineering of ultrathin nanomembranes by controlling the composition and structure of precursor molecules and their monolayers.

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.

A series of luminescent bis-cyclometalated gold(III) complexes with different nuclearities and various alkynyl ligands derived from hexaphenylbenzene (HPB) and hexabenzocoronene (HBC) have been synthesized. The energies of the low-energy metal-perturbed intraligand (IL) π-π*(R-C^N^C) absorptions of the HPB-alkynyl gold(III) complexes have been fine-tuned by attaching various substituent groups to the bis-cyclometalating ligands. Similarly, the metal-perturbed 3 IL [π→π*(R-C^N^C)] emissions of the complexes show energy shifts according to the electronic nature of the bis-cyclometalating ligands. On the contrary, the absorption and emission spectra of the HBC-alkynyl gold(III) complex have been assigned as dominated by the IL transitions of the HBC-alkynyl unit, as supported by transient absorption studies. The supramolecular assembly morphologies of the gold(III) complexes have been studied by TEM and SEM, along with comparisons across different complexes based on the molecular structures, and their assembly processes monitored by concentration-dependent and variable-temperature 1 H NMR spectroscopy studies.

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...

The effective and safe capture and storage of radioactive iodine (129I or 131I) is of significant importance during nuclear waste storage and nuclear energy generation. Here we present detailed evidence of highly efficient and reversible iodine capture in hexaphenylbenzene-based conjugated microporous polymers (HCMPs), synthesized via Buchwald–Hartwig (BH) cross-coupling of a hexakis(4-bromophenyl)benzene (HBB) core and aryl diamine linkers. The HCMPs present moderate surface areas up to 430 m2 g−1, with narrow pore size distribution and uniform ultra-micropore sizes of less than 1 nm. Porous properties are controlled by the strut lengths and rigidities of linkers, whilst porosity and uptake properties can be tuned by changing the oxidation state of the HCMPs. The presence of a high number of amine functional groups combined with microporosity provides the HCMPs with extremely high iodine affinity with uptake capacities up to 316 wt%, which is, to the best of our knowledge, the highest reported to date. Two ways to release the adsorbed iodine were explored: either slow release into ethanol or quick release upon heating (with a high degree of control). Spectral studies indicate that the combination of microporosity, amine functionality and abundant π-electrons ensured well-defined host−guest interactions and controlled uptake of iodine. In addition, the HCMPs could be recycled whilst maintaining 90% iodine uptake capacity (up to 295%). We envisage wider application of these materials in the facile uptake and removal of unwanted oxidants from the environment.

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 study of their crystal engineering, various interesting applications of HAB derivatives, and future possibilities and capabilities of this still underexplored scaffold.

Novel conjugated polymers such as poly(phenylene-fluorene) P1 and poly(triphenylbenzene-fluorene) P2 with hexaphenylbenzene (HPB) as a pending side group were prepared by Suzuki coupling using the dibromo monomers M1 and M2 with 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester, respectively. The HPB moiety of P1 and P2 can be oxidatively cyclodehydrogenated with FeCl3 in nitromethane, yielding polymers P3 and P4 with hexa-peri-hexabenzocoronene (i.e., nanographene) units. The cyclodehydrogenation of nanographene-containing polymers was confirmed by FT-IR spectroscopy. In addition, X-ray powder diffraction of both P3 and P4 revealed a polymer interlayer spacing of 1.3 nm being dominated by the nanographenes. The glass transition temperatures (Tgs) of P1 and P2 were 202 °C and 235 °C, respectively, while both P3 and P4 with nanographenes possessed Tgs higher than 300 °C. Compared to P3, P4 with a triphenylbenzene moiety in its backbone can be well dispersed without aggregation in N-cyclohexyl-2-pyrrolidone (CHP), as confirmed by UV-Vis spectroscopy, photoluminescence spectroscopy (PL) and photoluminescence-excitation (PLE) maps.

Efficient reactions between fluorine-functionalised biphenyl and terphenyl derivatives with catechol-functionalised terminal groups provide a route to large, discrete organic molecules of intrinsic microporosity (OMIMs) that provide porous solids solely by their inefficient packing. By altering the size and substituent bulk of the terminal groups, a number of soluble compounds with apparent BET surface areas in excess of 600m(2)g(-1) are produced. The efficiency of OMIM structural units for generating microporosity is in the order: propellane>triptycene>hexaphenylbenzene>spirobifluorene>naphthyl=phenyl. The introduction of bulky hydrocarbon substituents significantly enhances microporosity by further reducing packing efficiency. These results are consistent with findings from previously reported packing simulation studies. The introduction of methyl groups at the bridgehead position of triptycene units reduces intrinsic microporosity. This is presumably due to their internal position within the OMIM structure so that they occupy space, but unlike peripheral substituents they do not contribute to the generation of free volume by inefficient packing.

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.

Hexaphenylbenzene-based porous organic polymers are prepared smoothly through palladium-catalyzed C–C coupling polymerization. According to the obtained nitrogen physisorption isotherms, the Brunauer–Emmett–Teller specific surface area for these polymers varies between 742 and 1148 m2 g–1. Gravimetric hydrogen adsorption isotherms show that the adsorption capacity for hydrogen is up to 1.5 wt % at 1.13 bar and 77 K. Thanks to the propeller-like structure, unique electronic feature, and efficient preparation, hexaphenylbenzene can be taken as a promising building block for designing porous polymers with special properties.

Hexa-peri-Hexabenzocoronene (HBC), as the smaller graphene fragment consisting of 13 fused benzene rings, possesses a strong tendency to stack together via π-electronic interaction. In this paper, the 1,2-(4-bromomethyl-1-yl) acetylene was alkylated by Grignard reagent to form corresponding 1,2-bis(p-pentadecanylphenyl)acetylene. Cobalt(0)-catalyzed cyclotrimerization was carried out to give hexaphenylbenzene analogue. This step was followed by intramolecular cyclodehydrogenation to yield the desired product HBC-C15. The identity and purity of the new compound was confirmed by UV-vis spectrometer and 1H NMR spectrum. Its thermal behavior and self-assembly were studied by differential scanning calorimetry and polarizing optical microscopy.

We report here the Diels−Alder reaction of octa(diphenylacetylene)silsesquioxane [DPA8OS] with tetraphenylcyclopentadienone or tetra(p-tolyl)cyclopentadienone to form octa(hexaphenylbenzene)octasilsesquioxane, (Ph6C6)8OS, or octa(tetratolyldiphenylbenzene)octasilsesquioxane, (p-Tolyl4Ph2C6)8OS. Likewise, tetra(p-tolyl)cyclopentadienone reacts with octa(p-tolylethynylphenyl)OS to form octa(pentatolylphenylbenzene)octasilsesquioxane (p-Tolyl5PhC6)8OS. These compounds, with molecular weights of 4685−5245 Da, were isolated and characterized using a variety of analytical methods. The crystal structure of DPA8OS offers a 3 nm3 unit cell with Z = 1. The crystal structure of (Ph6C6)8OS was determined to have a triclinic unit cell of 11 nm3 with Z = 1. The latter structure is believed to be the largest discrete molecular structure reported with 330 carbons. Efforts to dehydrogenatively cyclize (Scholl reaction) the hexaarylbenzene groups to form 3-D octgraphene compounds are described.

To improve the lithium ion conductivities of currently used electrolytes, it is critical to understand how the transport of the lithium ions within the matrix is influenced by their interactions with solvating moieties. Therefore, well-defined model compounds based on cyclotriphosphazene (CTP) and hexaphenylbenzene (HPB) cores were prepared, bearing side groups containing the structural element of ethylene carbonate, which is the common solvent for lithium salts used as electrolytes in Li-ion batteries. All model compounds were highly pure and thermally stable up to at least 250 °C, covering a broad range of glass transition temperatures from −79 °C up to +3.5 °C. The temperature-dependent ionic conductivities of the blends follow a William−Landel−Ferry (WLF) type behavior with the corresponding glass transition temperatures as reference. Though the glass transition temperatures of the blends are low, their conductivities are only in the range of typical polymer electrolytes, implying that the coordinatio...

The thermodynamic and structural study of a series of polyphenylbenzenes, from benzene, n(Ph) = 0, to hexaphenylbenzene, n(Ph) = 6, is presented. The available literature data for this group of compounds was extended by the determination of the relevant thermodynamic properties for 1,2,4-triphenylbenzene, 1,2,4,5-tetraphenylbenzene, and hexaphenylbenzene, as well as structural determination by X-ray crystallography for some of the studied compounds. Gas phase energetics in this class of compounds was analyzed from the derived standard molar enthalpies of formation in the gaseous phase. The torsional profiles relative to the phenyl-phenyl hindered rotations in some selected polyphenylbenzenes, as well as the gas phase structures and energetics, were derived from quantum chemical calculations. In the ideal gas phase, a significant enthalpic destabilization was observed in hexaphenylbenzene relative to the other polyphenylbenzenes, due to steric crowding between the six phenyl substituents. A relatively low enthalpy of sublimation was observed for hexaphenylbenzene, in agreement with the decreased surface area able to establish intermolecular interactions. The apparently anomalous low entropy of sublimation observed for hexaphenylbenzene is explained by its high molecular symmetry and the six highly hindered phenyl internal rotations. For the series of polyphenylbenzenes considered, it was shown that the differentiation in the entropy of sublimation can be chiefly ascribed to the torsional freedom of the phenyl substituents in the gas phase and the entropy terms related with molecular symmetry.

Original glycodendrimers emanating from propargylated hexaphenylbenzene cores and containing up to 54 peripheral sugar ligands have been synthesized by Cu(I)-catalyzed [1,3]-dipolar cycloadditions using both convergent and divergent approaches.

In this article, four "A(3)+B(2)+C(2)"-type hyperbranched conjugated polymers (P1-P4) containing hexaphenylbenzene as the core were synthesized successfully for the first time with high yields through one-pot Suzuki polymerization reaction. The copolymerization percent of 1,3,4-oxadiazole units was adjusted to investigate the effect of polymer composition on the physical, optical, and EL properties. All polymers were well-characterized and exhibited good solubility, film-forming ability, and thermal stability. Both the solution and the films of these hyperbranched polymers emitted pure and stable deep-blue light emission, and their PL spectra did not change after annealing at 150 degrees C for 0.5 h in air, indicating that the hyperbranched structure, coupled to the introduced hexaphenylbenzene moieties, effectively suppressed the formation of aggregation excimer and keto defects. Two-layer PLED devices were fabricated to investigate the electroluminescence properties of these hyperbranched polymers, and P3 demonstrated a maximum luminance efficiency of 0.72 cd/A and a maximum brightness of 549 cd/m(2) at 16.5 V.

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.