para‐Phenylene‐Bridged Spirobi(triarylamine) Dimer with Four Perpendicularly Linked Redox‐Active π Systems

Abstract

para-Phenylene-bridged spirobi(triarylamine) dimer 2, in which π conjugation through four redox-active triarylamine subunits is partially segregated by the unique perpendicular conformation, was prepared and characterized by structural, electrochemical, and spectroscopic methods. Quantum chemical calculations (DFT and CASSCF) predicted that the frontier molecular orbitals of 2 are virtually fourfold degenerate, so that the oxidized states of 2 can give intriguing electronic and magnetic properties. In fact, the continuous-wave ESR spectroscopy of radical cation 2(*+) showed that the unpaired electron was trapped in the inner two redox-active dianisylamine subunits, and moreover was fully delocalized over them. Magnetic susceptibility measurements and pulsed ESR spectroscopy of the isolated salts of 2, which can be prepared by treatment with SbCl(5), revealed that the generated tetracation 2(4+) decomposed mainly into a mixture of 1) a decomposed tetra(radical cation) consisting of a tri(radical cation) moiety and a trianisylamine radical cation moiety (≈75%) and 2) a diamagnetic quinoid dication in a tetraanisyl-p-phenylendiamine moiety and two trianisylamine radical cation moieties (≈25%). Furthermore, the spin-quartet state of the tri(radical cation) moiety in the decomposed tetra(radical cation) was found to be in the ground state lying 30 cal mol(-1) below the competing spin-doublet state.

Preparation and Comparison of Chemical Properties of Phenazasiline Monomer, Dimer, Trimer, and Polymer

“…[1] Phenazasiline (Scheme 1, X = SiR 1 R 2 ), which has a Si-bridged diphenylamine framework, is one of these compounds. Phenazasiline derivatives are known to be potentially useful as a hole transporting layer for organic electroluminescent (EL) devices, [2][3][4] high spin molecules, [5][6][7] and antioxidants. [8] Generally, phenazasilines have been prepared via 2,2'-dibromodiphenylamine derivatives.…”

“…[8] Generally, phenazasilines have been prepared via 2,2'-dibromodiphenylamine derivatives. [3,[5][6][7][8][9][10] On the other hand, new methods for preparation of phenazasilines without using dibromide have been reported. [2,11,12] Phenazasiline-containing polymers often show characteristic physical and chemical properties.…”

“…Phenazasiline derivatives are known to be potentially useful as a hole transporting layer for organic electroluminescent (EL) devices, high spin molecules, and antioxidants . Generally, phenazasilines have been prepared via 2,2’‐dibromodiphenylamine derivatives . On the other hand, new methods for preparation of phenazasilines without using dibromide have been reported .…”

Intra- and Intermolecular Charge Transfer in Aggregates of Tetrathiafulvalene-Triphenylmethyl Radical Derivatives in Solution

“…In summary, the supramolecular properties of dyad 1 and its derivatives, which have a bulky paramagnetic group attached to the TTF core, are based on the interplay between IET and intermolecular CT processes. The understanding of this dynamic system is crucial to control its multifunctionality and to fully exploit its potential for applications in the field of molecular electronics and spintronics. ,− …”