Explorations of the Indenofluorenes and Expanded Quinoidal Analogues.

Highly conjugated hydrocarbons have attracted interest for use as active materials in electronic devices such as organic field effect transistors (OFET) and organic photovoltaics (OPV). In this Account, we review our progress in synthesizing and studying a new class of small molecules for potential use as organic semiconductors. The idea originated from prior research on octadehydrodibenz[12]annulene, as the system can undergo double transannular cyclization to yield the indeno[1,2-b]fluorene skeleton.

High operational and environmental stability of high-mobility conjugated polymer field-effect transistors through the use of molecular additives.

Due to their low-temperature processing properties and inherent mechanical flexibility, conjugated polymer field-effect transistors (FETs) are promising candidates for enabling flexible electronic circuits and displays. Much progress has been made on materials performance; however, there remain significant concerns about operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode displays. Here, we investigate the physical mechanisms behind operational and environmental degradation of high-mobility, p-type polymer FETs and demonstrate an effective route to improve device stability.

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing.

We report a new synthetic route to 5,11-disubstituted indeno[1,2-b]fluorene-6,12-diones that is amenable to larger scale reactions, allowing for the preparation of gram amounts of material. With this new methodology, we explored the effects on crystal packing morphology for the indeno[1,2-b]fluorene-6,12-diones by varying the substituents on the silylethynyl groups.

Experimental and computational studies of the neutral and reduced states of indeno[1,2-b]fluorene.

This study examines the intrinsic structural and optoelectronic properties of the neutral indeno[1,2-b]fluorene skeleton as well as those of the corresponding anion radical and dianion. We report their characterization by analysis of solid-state structures and EPR, NMR, and absorbance spectra. Additionally, 20 popular density functional theory methods are used to evaluate their performance for predicting NMR chemical shifts, EPR hyperfine coupling constants, and low-energy transitions of the absorbance spectrum to act as a guide for future studies.

Molecular characterization of reactive oxygen species in systemic and pulmonary hypertension.

Hypertension, commonly recognized as high blood pressure, is a serious disease that affects millions of people worldwide. Similar to many physiological disorders, hypertension consists of several different cellular signaling pathways that involve various molecular messengers. Recent studies have shown that reactive oxygen species (ROS) play a substantial role in the development of both systemic and pulmonary hypertension, contributing to the pathology of this disease.

6,12-Bis[(tri-cyclo-hexyl-sil-yl)ethyn-yl]indeno-[1,2-b]fluorene.

The title compound, C60H76Si2, a formally anti-aromatic system containing 20-π electrons, contains a rare p-xylylene motif. This is displayed by the alternating short and long bonds. The outer rings possess nearly homogenous bond lengths.

Molecular mechanisms of reactive oxygen species-related pulmonary inflammation and asthma.

Asthma is a highly relevant disorder that can be induced by many environmental factors such as allergens and pollutants. One of the most critical pathological symptoms of asthma is airway inflammation. In order to identify a cause of respiratory inflammation, we thoroughly examine the unique role of reactive oxygen species (ROS).

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.

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).

Fluoreno[4,3-c]fluorene: a closed-shell, fully conjugated hydrocarbon.

The synthesis and optoelectronic properties of 24 π-electron, formally antiaromatic 4,11-di-t-butyl-1,8-dimesitylfluoreno[4,3-c]fluorene (FF) are presented. The solid-state structure shows that the outer rings are aromatic, while the central four rings possess a bond-localized 2,6-naphthoquinone dimethide motif (in red). The biradical character of FF is assessed experimentally and computationally; the results of which implicate a closed-shell ground state.

Synthesis, crystal structures, and photophysical properties of electron-accepting diethynylindenofluorenediones.

A series of 6,12-bis[(trialkylsilyl)ethynyl]indeno[1,2-b]fluorene-5,11-diones has been synthesized. X-ray crystallographic analysis of these compounds reveals that triisopropylsilyl (TIPS) substitution on the alkyne terminus affords the largest number of intermolecular π-π interactions in the solid state. Conversely, use of trialkylsilyl groups smaller or larger than TIPS furnishes a variety of crystal-packing motifs that contain fewer π-π interactions.