Synthesis of Cyano‐Substituted Diaryltetracenes from Tetraaryl[3]cumulenes

Abstract

A versatile, two-step synthesis of highly substituted, cyano-functionalized diaryltetracenes has been developed, starting from easily accessible tetraaryl[3]cumulenes. This unprecedented transformation is initiated by [2+2] cycloaddition of tetracyanoethylene (TCNE) to the proacetylenic central double bond of the cumulenes to give an intermediate zwitterion, which after an electrocyclization cascade and dehydrogenation yields 5,5,11,11-tetracyano-5,11-dihydrotetracenes in a one-pot procedure. A subsequent copper-assisted decyanation/aromatization provided the target 5,11-dicyano-6,12-diaryltetracene derivatives. All of the postulated structures were confirmed by X-ray crystallography. The new chromophores are thermally highly stable and feature promising fluorescence properties for potential use in optoelectronic devices. They are selective chemosensors for Cu(I) ions, which coordinate to one of the CN substituents and form a 1:1 complex with an association constant of Ka =1.5×10(5) L mol(-1) at 298 K.

Porphyrin Donor and Tunable Push–Pull Acceptor Conjugates—Experimental Investigation of Marcus Theory

“…All experimental methods, synthesis, and characterization are provided in the Supporting Information (Sections S1, S2 and S10). The Supporting Information contains the synthesis and full characterization of all new compounds, as well as copies of their 1 Ha nd 13 CNMR spectra, X-ray crystallography details and CIF files for compounds 12 and 16,c yclic voltammetry (CV), rotating disk voltammetry (RDV) and UV/Vis spectroelectrochemical data and spectral traces, quantum chemical calculations (DFT) on the conjugates and control compounds, UV/Vis spectra of the conjugates and control compounds, detailed report on the transient absorption spectroscopic measurements, and Marcus curves. CCDC 1051625 (12)a nd 1431981 (16)c ontain the supplementary crystallographic data.…”

Push–Pull Buta‐1,2,3‐trienes: Exceptionally Low Rotational Barriers of Cumulenic CC Bonds and Proacetylenic Reactivity

“…Zwitterions 14 a-c give two reversible one-electron reduction steps and an irreversible two-electron oxidation step associated on the reverse scan to as mall amplitude peak at + 0. [8], and torsional angles [8]: 14 a C4AÀN4A 1.342(2), C4BÀ N4B 1.340(2), C3ÀC4 1.395(3), C3ÀC3D1.401(3);C 4-C3-C3D 126.0(2), C1-C2-C3-C4 À120.2(2); 15 b:C 1AÀN1A 1.440(1), C1BÀN1B 1.450(1), C3ÀC4 1.408(2), C3ÀC3D1.405(2);C4-C3-C3D 121.1(1), C1-C2-C3-C4 À35.9 (1). The quinoid character dro ft he anilinorings is calculated from the bond lengths in aniline moieties using the following formula: dr = {[(a + b)/2Àc] + [(a' + b')/ 2Àc']}/2 (in benzene, dr = 0; in fully quinoid rings, dr = 0.10-0.12 ).…”

“…More recently,w ep roposed the intermediacy of such zwitterions in the reaction of symmetrically substituted tetraaryl [3]cumulenes with TCNE at higher temperature (90-140 8C) in dipolar-aprotic solvents, leadingultimately to 5,11-dihydrotetracenes. [8,17] We coined the term" proacetylenic" to describe the acetylene-types tructure and reactivity of the central C=Cb ond in [3]cumulenes, [14] in analogy to the concept of proaromaticity of quinoidc hromophores. [18] According to Chauvin et al,b ut-3en-1-yne is significantly more "aromatic" than buta-1,2,3triene.…”

Mono‐ and Bis(imidazolidinium ethynyl) Cations and Reduction of the Latter To Give an Extended Bis‐1,4‐([3]Cumulene)‐p‐carboquinoid System

“…[2] Shorter cumulenes, such as [3]cumulenes,w ere first reported by Brand in the early 1920s. [5,6] More recently,Diederich and co-workers have looked at the synthesis and reactivity of these systems [7,8] and an umber of push-pull/donor-acceptor [3]cumulenes. [9,10] Ueta et al have also reported the [2+ +2] cycloaddition of a[3]cumulene with tetracyanoethene.…”