Blue-Emitting Arylalkynyl Naphthalene Derivatives via a Hexadehydro-Diels–Alder Cascade Reaction

Abstract

We describe here three alkynyl substituted naphthalenes that display promising luminescence characteristics. Each compound is easily and efficiently synthesized in three steps by capitalizing on the hexadehydro-Diels–Alder (HDDA) cycloisomerization reaction in which an intermediate benzyne is captured by tetraphenylcyclopentadienone, a classical trap for benzyne itself. These compounds luminesce in the deep blue when stimulated either optically (i.e., photoluminescence in both solution and solid films) or electrically [in a light-emitting diode (LED)]. The photophysical properties are relatively insensitive to the electronic nature of the substituents (H, OMe, CO2Me) that define these otherwise identical compounds. Overall, our observations suggest that the twisted nature of the five adjacent aryl groups serves to minimize the intermolecular interaction between core naphthalene units in different sample morphologies. These compounds represent promising leads for the identification of others of value as the emissive component of organic LEDs (OLEDs).

Discussion Addendum for: The Direct Acyl-Alkylation of Arynes. Preparation of Methyl 2-(2-acetylphenyl)acetate

“…The Hoye group has vigorously studied the generation of arynes via an unusual hexadehydro-Diels-Alder reaction (HDDA, Figure 5). 43,44 Areas of study in the field are numerous, including Lewis-acid-promoted C-H insertion, 45 domino reactions, 46,47 photochemistry, 48,49 mechanistic studies, 50,51 multicomponent reactions, 52 and natural product diversification. 53 The regioselectivity for the ensuing insertion process is influenced by both the choice of nucleophile and the substituents on the aryne system.…”

Benzocyclobutadienes: An Unusual Mode of Access Reveals Unusual Modes of Reactivity

“…The presence of a TMS group in the aryl‐substituted triyne led to improved yields and facilitated the solubility and handling of some of the products. Some of the products exhibited blue fluorescence upon exposure to a 365 nm light source (see the Supporting Information for two examples) …”

“…Some of the products exhibited blue fluorescence upon exposure to a 365 nm light source (see SI for two examples). [12] …”

“Dial‐In” Emission from a Unique Flexible Material with Polarization Tuneable Spectral Intensity

“…Therefore, with the focus on such drawbacks, the field is slowly switching to the development of luminescent organic materials. Extensive research has been done on conjugated fluorophore based diodes, whereas reports on intact π‐stacked 3D photoluminescent polymer films is limited . After thorough examination of literature examples, we believe that with modification of the existing systems would provide superior materials with excellent features related to sensing, organic light‐emitting diodes (OLEDs), catalysis, etc.…”