Michael M. Haley

Synthesis and properties of annulenic subunits of graphyne and graphdiyne nanoarchitectures

This report describes the synthetic strategies toward and optoelectronic properties of substructures of the non-natural, planar carbon networks graphyne and graphdiyne, which are based on the dehydrobenzo[12]annulene and dehydrobenzo[18]annulene framework, respectively.

6,12-Diarylindeno(1,2-b)fluorenes: Syntheses, Photophysics, and Ambipolar OFETs

Herein we report the synthesis and characterization of a series of 6,12-diarylindeno[1,2-b]fluorenes (IFs). Functionalization with electron donor and acceptor groups influences the ability of the IF scaffold to undergo two-electron oxidation and reduction to yield the corresponding 18- and 22-π-electron species, respectively. A single crystal of the pentafluorophenyl-substituted IF can serve as an active layer in an organic field-effect transistor (OFET). The important finding is that the single-crystal OFET yields an ambipolar device that is able to transport holes and electrons.

Carbon-rich compounds : from molecules to materials

Foreword.Preface.List of Contributors.1. Pioneers of Carbon-rich Compounds.2. Electronic Conduction in Photoactive Metallo-wires.3. All-benzenoid Polycyclic Aromatic Hydrocarbons: Synthesis, Self-assembly and Applications in Organic Electronics.4. [N]Phenylenes: a Novel Class of Cyclohexatrienoid Hydrocarbons.5. A Solid State Strategy for the Preparation of Carbon-rich Polymers.6. Chiral Carbon-rich Macrocycles and Cyclophanes.7. Carbon-rich Cycles with Two and More 1,3-Butadiyne Units ? Syntheses, Structures and Reactivities.8. Carbon-rich Structures: Computational Considerations.9. Fullerene Reactivity - Fullerene Cations and Open-Cage Fullerenes.10. Polyynes.11. Defined-length Carbon-rich Conjugated Oligomers.12. Synthesis and Chemistry of Polycyclic Aromatic Hydrocarbons with Curved Surfaces: Buckybowls.13. Reduction of Carbon-rich Compounds.Index.

Electron-accepting 6,12-diethynylindeno[1,2-b]fluorenes: synthesis, crystal structures, and photophysical properties.

Polycyclic hydrocarbons that possess extended p conjugation are of significant interest because of their potential use in optical and electronic devices such as light emitting devices, field-effect transistors, and photovoltaics. While a majority of studies have focused on acenes such as pentacene and its derivatives (e.g., 1; Scheme 1), these systems are susceptible to oxidative and photolytic degradation; thus, there is a need for alternative, acene-like molecules. One avenue in this search has explored compounds containing five-membered rings, rather than the more traditional six-membered rings. Prime examples of such molecules are dibenzopentalene (2) and derivatives thereof, wherein the groups of Saito, Kawase, and Tilley have recently described improved methods for their construction.

Macrocyclic Oligo(phenylacetylenes) and Oligo(phenyldiacetylenes)

The following is a comprehensive survey of the chemistry of macrocycles comprised entirely of phenyl and acetylenic moieties. Although over four decades old, this area of research has come into its own just in the last few years. Widespread interest in the field has been spurred by recent discoveries utilizing these compounds as ligands for organometallic chemistry, hosts for binding guest molecules, models of synthetic carbon allotropes, and precursors to fullerenes and other carbon-rich materials. This review will discuss the preparation of a tremendous variety of novel structures and detail the development of versatile synthetic methods for macrocycle construction.

Synthesis of Expanded Graphdiyne Substructures

Graphdiyne (1) is a member of a novel family of interesting and potentially important allotropes of carbon. Reported herein are the synthesis and spectroscopic characterization of model substructures 2-6. The macrocycles were prepared by the intramolecular cyclization of suitable alpha,omega-polyynes. Key to the success of this approach was the development of an in situ protiodesilylation/alkynylation reaction utilizing reactive phenylbutadiyne synthons. This new method has allowed for the preparation of the largest, most complete substructures of the graphdiyne network to date (3-6).

Indeno[2,1-c]fluorene: A New Electron-Accepting Scaffold for Organic Electronics

A new class of fully conjugated indenofluorenes has been synthesized and confirmed by solid-state structure analysis. These indeno[2,1-c]fluorene molecules, containing an antiaromatic as-indacene core (in red), possess high electron affinities and show a broad absorption that reaches into the near-IR region of the electromagnetic spectrum. All of the featured compounds reversibly accept up to two electrons. Their electronic properties make this class of compounds attractive for applications in organic electronic devices.

Diindeno-fusion of an anthracene as a design strategy for stable organic biradicals

The consequence of unpaired electrons in organic molecules has fascinated and confounded chemists for over a century. The study of open-shell molecules has been rekindled in recent years as new synthetic methods, improved spectroscopic techniques and powerful computational tools have been brought to bear on this field. Nonetheless, it is the intrinsic instability of the biradical species that limits the practicality of this research. Here we report the synthesis and characterization of a molecule based on the diindeno[b,i]anthracene framework that exhibits pronounced open-shell character yet possesses remarkable stability. The synthetic route is rapid, efficient and possible on the gram scale. The molecular structure was confirmed through single-crystal X-ray diffraction. From variable-temperature Raman spectroscopy and magnetic susceptibility measurements a thermally accessible triplet excited state was found. Organic field-effect transistor device data show an ambipolar performance with balanced electron and hole mobilities. Our results demonstrate the rational design and synthesis of an air- and temperature-stable biradical compound.

Quinoidal diindenothienoacenes: synthesis and properties of new functional organic materials

We report the preparation and characterization of a new class of quinoidal thienoacenes. The synthetic route is efficient, high-yielding and scalable with the potential for further functionalization. Single crystal X-ray diffraction reveals that, as size increases, the molecules pack in progressively closer 1D arrangements. The title compounds are shown to have amphoteric redox behaviour by cyclic voltammetry. The anion radicals are studied by EPR spectrometry and by computations. The electron-accepting nature, NIR absorption and the low-lying LUMO energies (ca. −4.0 eV) allude to potential use in materials applications.

Selective Nitrate Binding in Competitive Hydrogen Bonding Solvents: Do Anion–π Interactions Facilitate Nitrate Selectivity?

New tripodal urea receptors demonstrate preferential binding of anions over competitive hydrogen bonding solvents. 1H NMR titrations in 10% DMSO-d6/CDCl3 show a higher affinity for nitrate over the halides for the fluorinated receptor, which is lost when the fluorines are removed. An “anion–π” interaction between the nitrate and the π-system of the ethynyl-substituted arene is proposed as the source of this selectivity.