A New Entry to Purely Organic Thermally Activated Delayed Fluorescence Emitters Based on Pyrido[2,3‐b]pyrazine–Dihydrophenazasilines Donor–Acceptor Dyad

Contributing to Biochemistry and Optoelectronics: Pyrrolo[1',2':2,3]imidazo[1,5-a]indoles and Cyclohepta[4,5]pyrrolo[1,2-c]pyrrolo[1,2-a]imidazoles via [3+2] Annulation of Acylethynylcycloalka[b]pyrroles with Δ1-Pyrrolines

Available pyrrolylalkynones with tetrahydroindolyl, cycloalkanopyrrolyl, and dihydrobenzo[g]indolyl moieties, acylethynylcycloalka[b]pyrroles, are readily annulated with Δ¹-pyrrolines (MeCN/THF, 70 °C, 8 h) to afford a series of novel pyrrolo[1',2':2,3]imidazo[1,5-a]indoles and cyclohepta[4,5]pyrrolo[1,2-c]pyrrolo[1,2-a]imidazoles functionalized with an acylethenyl group in up to an 81% yield. This original synthetic approach contributes to the arsenal of chemical methods promoting drug discovery. Photophysical studies show that some of the synthesized compounds, e.g., benzo[g]pyrroloimidazoindoles, are prospective candidates for TADF emitters of OLED.

Controllable construction of red thermally activated delayed fluorescence molecules based on a spiro-acridine donor

Red and near-infrared (NIR) thermally activated delayed fluorescence (TADF) molecules show excellent potential applications in organic light-emitting diodes (OLEDs). Due to the lack of systematic studies on the relationship between molecular structures and luminescence properties, both the species and amounts of red and NIR TADF molecules are far from meeting the requirements for practical applications. Herein, four new efficient molecules (DQCN-2spAs, TPCN-2spAs, DPCN-2spAs and BPCN-2spAs) are proposed and their photophysical properties are theoretically predicted based on first-principles calculations and thermal vibration correlation function (TVCF) theory. The results show that all molecules exhibit red or NIR emissions and they have fast radiative decay rates and reverse intersystem crossing (RISC) rates, and the excellent TADF luminescence properties are predicted. Moreover, based on spiro-acridine (spAs) as the donor unit, the combination with different acceptors can change the dihedral angle between the ground state and the excited state, the bending degree of the donor is positively correlated with the reorganization energy, and this feature can have a great influence on the non-radiative process. Furthermore, based on these theoretical predictions, experimental verifications are performed and the synthesized BPCN-2spAs is confirmed to be an efficient NIR TADF molecule. Thus, the relationships between basic molecular structures and photophysical properties are revealed, a feasible design strategy is applied and four promising red and NIR TADF molecules are proposed. All these results could contribute to the development of red and NIR TADF emitters and OLEDs.

A Review on the Synthesis of Fluorescent Five- and Six-Membered Ring Azaheterocycles

Azaheterocycles rings with five and six members are important tools for the obtaining of fluorescent materials and fluorescent sensors. The relevant advances in the synthesis of azaheterocyclic derivatives and their optical properties investigation, particularly in the last ten years, was our main objective on this review. The review is organized according to the size of the azaheterocycle ring, 5-, 6-membered and fused ring azaheterocycles, as well as our recent contribution on this research field. In each case, the reaction pathways with reaction condition and obtained yield, and evaluation of the optical properties of the obtained products were briefly presented.