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Organic neutral radicals have long fascinated chemists with a fundamental understanding of structure-reactivity relationships in organic reactions and with applications as new functional materials. However, the elusive nature of these radicals makes the synthesis, isolation, and characterization very challenging. In this work, the synthesis of three long-lived, fluorenyl-based radicals are reported. The geometry and electronic structures of these radicals were systematically investigated with a combination of various experimental methods, besides density functional theory (DFT) calculations, which include X-ray crystallographic analysis, electron spin resonance (ESR), electron nuclear double resonance (ENDOR), cyclic voltammetry, and UV-vis-NIR measurements. Their half-life periods (τ1/2) in air-saturated solution under ambient conditions were also determined. Surprisingly, all three radicals showed remarkable stabilities: τ1/2 = 7, 3.5, and 43 days.

Series of light emitting polymers based on dibenzofluorene-acene have been synthesized through aromatic nucleophilic substitution reaction. The polymer displayed strong solubility in specific organic solvents with a polydispersity index of 1.5–2.0 and weight average molecular weight within the range from 25000 to 34000. At 420 nm the highest photoluminescence of the polymer solution was observed. The temperature of the thermal decomposition was determined by TGA and ranged from 300 to 446 °C while the value of Tg was between 120 and 140 °C. Cyclic voltammetry tests of polydibezofluorenes show that the compounds with HOMO and LUMO in the range 2.23–5.26 eV is stable under redox condition. The optical properties of these polydibenzofluorenes showed significant blue emissions in the polymers obtained.

Molecules of 13H-dibenzo[a,i]fluoren-13-one, C21H12O, straddle a crystallographic mirror plane and are essentially planar, with a dihedral angle of only 1.9 (1)° between the two naphthalene ring systems. Repulsive intramolecular C=O...H interactions therefore do not explain the larger distortions found in isomeric ketones.

Because of the steric bulkiness and the η5/κ1-constrained-geometry-configuration (CGC) geometry, the entire range of pyridyl-methylene-fluorenyl-stabilized rare earth metal bisalkyl complexes, (Flu-CH2-Py)Ln(CH2SiMe3)2(THF)x (Flu = fluorenyl; Py = pyridyl; for 1, Ln = Sc and x = 0; for 2-11, Ln = Lu, Tm, Er, Ho, Y, Dy, Tb, Gd, Nd, or Pr and x = 1), and monoalkyl complex, (Flu-CH2-Py)2La(CH2SiMe3) (THF) (12), has been successfully achieved for the first time via the sequential salt metathesis reactions. Activated by [Ph3C][B(C6F5)4] and AliBu3, complexes 1-9 showed high activity and perfect syndioselectivity for styrene polymerization, while the large Nd- and Pr-attached precursors 10 and 11 exhibited slightly decreased syndioselectivity but rather low activity; the monoalkyl La precursor 12 was completely inert. The activity increased with the decrease in the rare earth metal size, in striking contrast to the literature that has shown that a large metal facilitates a high activity, which was also not a result of an enthalpic effect (ΔH≠) or an entropic effect (ΔS≠) according to Eyring plots. The types of organoborates and the aluminum alkyls, the electron donors, and the polarity of the reaction medium, which affected the coordination of styrene to the active species, aroused significantly different catalytic activity, indicating that styrene coordination played the key role in the polymerization process. On the basis of this, the density functional theory calculation of the active species in the model of [(Flu-CH2-Py)Ln-nC17H19]+ revealed whenever the orbitals of the pyridyl-methylene fluorenyl ligand overlapped with those of the rare earth metals, the LUMO energy of the active species was lowered and thus the catalytic activity was high. Therefore, the LUMO energy of the active species could be adopted as a potential criterion to estimate the activity of a catalytic system for styrene polymerization. This work reveals for the first time the power of the pyridyl-methylene fluorenyl ligand and the nature of the factors influencing the catalytic performance.

A novel compound which is useful as a constitutional component for an organic EL device is provided by an aminodibenzofluorene derivative comprising (A) at least one dibenzofluorene structure and (B) at least one amino group in a molecule, a material for an organic electroluminescence (EL) device comprising the same, a light emitting material for an organic EL device, a light emitting organic solution, an organic EL device in which an organic compound layer comprising a single layer or plural layers including at least a light emitting layer is interposed between a pair of electrodes, wherein at leas one layer in the organic compound layer described above contains at least one kind of the aminodibenzofluorene derivative described above and an equipment comprising the same. A practical organic EL device which has a low operating voltage, a long lifetime and a high current efficiency and which provides blue light emission having an excellent color purity is materialized by using the above compound.

Solution-spray flash vacuum thermolysis of di-1-naphthyldiazomethane (9) results in the formation of dibenzo[c,g]fluorene (12), formed via a carbene- carbene rearrangement of di-1-naphthylcarbene (10). The isomeric dibenzo[α,i]fluorene (11) claimed by Franzen and Joschek (Liebigs Ann. Chem. 1960, 633, 7) is not formed, and no dibenzofluorene is formed on thermolysis in boiling naphthalene. 11 is formed on dehydration of di-1-naphthylcarbinol (14) with phosphoric acid, but the claimed tetra-1-naphthylethylene (13) is not formed, and the so-called ethylenization of diarylcarbinols is cast in doubt generally. The compound previously believed to be 13 is 13-[di(1- naphthyl)methyl]-dibenzo[α,i]fluorene (22). The alleged cleavage of 13 into two molecules of carbene 10 is unsubstantiated.

Alkylation of enamines and enamine salts by benzylic and (β-haloethyl)aryl halides, respectively, followed by acidic cyclodehydration and dehydrogenation provides an efficient synthetic approach to a wide range of polycyclic aromatic compounds of diverse structural types.Specific polycyclic hydrocarbons synthesized by this route include benzo- and benzofluorene, 7H-dibenzo-, 13H-dibenzo-, and 13H-dibenzofluorene, 15H-tribenzofluorene, dibenzochrysene, benzopentaphene, indenofluorene, fluorenofluorene, octahydrodibenzanthracene, dibenzanthracene, octahydrodibenzanthracene, dibenzanthracene, picene, benzopicene, 1H-benzaceanthrylene, and 4H-cyclopentachrysene.This method with appropriate modifications appears to be potentially broader in scope than established traditional methods of polycyclic hydrocarbon synthesis.

Rearrangement of α-alkoxycarbonyldiarylmethyl cations lead to 9-fluorenecarboxylic esters.Decarboxylation of these esters generates the fluorene derivatives 9a-f.The precursors to the cations are the α-hydroxyesters 6a-g.This conversion constitutes a facile synthesis of benzofluorenes.