High-Spin Radical Cations of a Dendritic Oligoarylamine

Oligotriarylamine-Extended Organoboranes with Tunable Electron-Donating Strength by Changing the Number of Donor Units

Triarylborane (Ar₃B) and triarylamine (Ar₃N) have been widely employed to construct electronically different donor-acceptor (D-A) systems. Herein, we describe a series of A-D-A-type luminescent organoboranes L-B₂N_n (n = 1, 3, 5) that show an increased number of Ar₃N units as electron donors and two terminal Ar₃B as acceptors. When the Ar₃N moieties were extended from one to five units, their electron-donating strength was gradually enhanced and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps could also be tuned, which was further reflected in the red-shifted emissions from blue (λ_em = 458 nm) to orange (λ_em = 595 nm) with a decrease in E_gap(elect) from 3.19 to 2.61 eV. L-B₂N₅ showed a huge Stokes shift (∼14 057 cm^-1) and a considerably bright emission with an enhanced solid-state quantum efficiency (Φ_S = 98%) compared with the other members. L-B₂N₃ and L-B₂N₅ exhibited aggregation-induced emissions (AIEs), and an apparent solvatochromic shift was also observed in the emission spectra as the solvent was changed from hexane to tetrahydrofuran (THF) (430 → 595 nm). In addition, the donor-acceptor charge-transfer character in these organoboranes caused a thermally responsive emission over a broad range.

A new architecture for high spin organics based on Baird's rule of 4n electron triplet aromatics

This work reports triplet aromatic high spin ground states of cyclopentadienyl cation polyads as alternative to high spin polyradicals or polycarbenes.

Radical Cation of an Oligoarylamine Having a Nitroxide Radical Substituent: A Coexistent Molecular System of Localized and Delocalized Spins

A trimer derivative of oligotriarylamine bearing a nitroxide radical substituent as a localized spin center {N,N-bis[4-(di-4-anisylamino)phenyl]-N-[3-tert-butyl-5-(N-tert-butyl-N-oxylamino)phenyl]amine (1)} was characterized by electrochemical, spectroelectrochemical, and electron paramagnetic resonance spectroscopic measurements. The first and second oxidations of 1 occurred from the triamine moiety, leaving the nitroxide radical moiety intact. The delocalized polaronic state in the triamine moiety was generated by one-electron oxidation of 1, indicating the coexistence of localized and delocalized spins on 1⁺, where an intramolecular antiferromagnetic interaction was detected.

Redox modulation of para-phenylenediamine by substituted nitronyl nitroxide groups and their spin states

Three kinds of para-phenylenediamine (PDA) derivatives bearing nitronyl nitroxide (NN) groups were prepared and characterized on the basis of the electrochemical, electron spin resonance (ESR) spectroscopic, absorption spectroscopic, and magnetic susceptibility measurements. It was clarified that the oxidation potential of the central PDA unit is strongly influenced by the numbers of substituted electron-withdrawing NN groups. In addition, the intervalence charge transfer in the central PDA unit was detected in the monocationic states of the PDAs with two NN groups, indicating the coexistence of the localized spins and the delocalized spin on theses molecules. Moreover, pulsed ESR measurements confirmed that the delocalized spin on the central PDA unit and the localized two spins on the NN groups were ferromagnetically coupled in the monocationic states.

Polymers for electronics and spintronics

This critical review is devoted to semiconducting and high spin polymers which are of great scientific interest in view of further development of the organic electronics and the emerging organic spintronic fields. Diversified synthetic strategies are discussed in detail leading to high molecular mass compounds showing appropriate redox (ionization potential (IP), electron affinity (EA)), electronic (charge carrier mobility, conductivity), optoelectronic (electroluminescence, photoconductivity) and magnetic (magnetization, ferromagnetic spin interactions) properties and used as active components of devices such as n- and p-channel field effect transistors, ambipolar light emitting transistors, light emitting diodes, photovoltaic cells, photodiodes, magnetic photoswitches, etc. Solution processing procedures developed with the goal of depositing highly ordered and oriented films of these polymers are also described. This is completed by the description of principal methods that are used for characterizing these macromolecular compounds both in solution and in the solid state. These involve various spectroscopic methods (UV-vis-NIR, UPS, pulse EPR), electrochemistry and spectroelectrochemistry, magnetic measurements (SQUID), and structural and morphological investigations (X-ray diffraction, STM, AFM). Finally, four classes of polymers are discussed in detail with special emphasis on the results obtained in the past three years: (i) high IP, (ii) high |EA|, (iii) low band gap and (iv) high spin ones.

Theoretical Study of Very High Spin Organic π-Conjugated Polyradicals

Different forms of pi-conjugated polyarylmethyl systems, such as diradicals, polyradicals, spin clusters, and polymers, were studied with valence bond (VB) calculations within the density matrix renormalization group (DMRG) framework. For these systems, the energy gap between the high-spin ground state and the lowest low-spin excited state (DeltaE(L-H)) was computed and found to correlate well with their stability. On the basis of our analysis, medium-sized polyarylmethyl cycles are suggested to be potential key building blocks of very high spin spin clusters and polymers.