Herein, we report a general strategy for achieving ultra-pure green emissions by suppressing the shoulder peaks in emission spectra of conventional polycyclic aromatic hydrocarbons (PAHs). Through precise synthetic fusion multi-resonance (MR) fragments with PAH, extended π-conjugation lengths, increased molecular rigidity, and reduced vibrational frequency could be simultaneously realized. The proof-of-concept emitters exhibited dominant at ca. 521 nm, photoluminescence quantum yields that...

The pursuit of ideal short-delayed thermally activated delayed fluorescence (TADF) emitters is hampered by the mutual exclusion a small singlet-triplet energy gap (ΔEST) and large oscillator strength (f). Here, attaching an multiresonance-acceptor onto sterically-uncrowded donor, we report TADF bearing hybrid electronic excitations with main donor-to-acceptor long-range (LR) auxiliary bridge-phenyl short-range (SR) charge-transfer characters, balancing ΔEST f. Moreover, incorporation dual...

Polycyclo-heteraborin multi-resonance (MR) emitters are promising for high color-purity organic light-emitting diodes (OLEDs). Here, unlike the most common heteroatom ternary-doped (X/B/N) frameworks, a binary-doped (B/N) skeleton is reported with large energy band wide-range color tunability. Based on this parent-segment, "one-pot" catalyst-free borylation method developed which generates deep blue to pure green MR from readily available starting materials, peaks at 426-532 nm and...

The pursuit of ideal narrowband yellow multiple resonance (MR) emitters is hampered by the mutual constraints effective spectral redshift and maintaining a small full width at half maximum (FWHM) value. Here, novel fusion molecular design strategy reported to break this trade-off. Compared with selected parent core, specific MR effects in target molecules can simultaneously extend π-conjugation length, increase rigidity structure, reduce vibrational frequency. Proof-of-the-concept BN-DICz...

Abstract A new class of highly efficient and stable, blue‐phosphorescent Pt II complexes based on a tetradentate chelating framework has been found to exhibit sensitive reversible responses multiple external stimuli including temperature, pressure, UV irradiation with distinct phosphorescent color switching—from blue red or white. Intermolecular excimer formation is the main origin this intriguing multi‐response phenomenon. Highly singlet‐oxygen sensitization by compounds yields...

New symmetric and unsymmetric B,N,B-doped benzo[4]helicenes 3-6 a/b have been achieved in good yields, using a three-step process, starting from N(tolyl)3 highly divergent manner (7 examples). A borinic acid functionalized 1,4-B,N-anthracene 1 was found to display unprecedented reactivity, acting as convenient effective precursor for selective formation of bromo-substituted B,N,B-benzo[4]helicenes 2 a/2 b via intramolecular borylation sequential B-Mes bond cleavage the presence BBr3 ....

Abstract Three isomeric boron‐containing thermally activated delayed fluorescent (TADF) emitters, namely m ‐AC‐DBNA, p and ′‐AC‐DBNA, are constructed by incorporating an electron‐donor acridine (AC) moiety into meta ‐, para or ′‐positions of electron‐accepting boron‐embedded rigid framework. The substitutional positions found to dramatically affect thermal, photophysical, electroluminescent (EL) properties. experimental results show that the ‐substituted compound ( ‐AC‐DBNA) exhibits higher...

With the aid of borylation and oxidative coupling reactions, six new polycyclic aromatic hydrocarbons (PAHs) doped by nitrogen–boron–nitrogen (NBN) units were achieved. The structure–optoelectronic property relationship for this group compounds was examined. All are fluorescent with contrasting emission colors quantum yields.

Nitrogen-containing polycyclic heteroaromatics have exhibited fascinating multi-resonance (MR) characteristics for efficient narrowband emission, but strategies to bathochromic shift their emissions while maintaining the narrow bandwidths remain exclusive. Here, homogeneous hexatomic rings are introduced into nitrogen-embedded MR skeletons prolong π-conjugation length low-energy electronic transitions retaining non-bonding character of remaining parts. The proof-of-the-concept emitters...

High-efficiency and stable deep-blue bottom-emitting organic light-emitting diodes with Commission Internationale de l'Eclairage

Despite the remarkable multiple resonance (MR) optoelectronic properties of organic nanographenes with boron and nitrogen atoms disposed para to each other, synthetic procedures are sophisticated low yields molecular skeletons limited. Here, a new paradigm easy-to-access MR emitter is constructed by simplifying multiborylation through amine-directed formation B-N bonds while introducing an additional para-positioned atom trigger effect. The proof-of-concept molecules exhibit narrowband...

Multi-resonant thermally activated delayed fluorescence (MR-TADF) materials have attracted considerable attention recently. The molecular design frequently incorporates cycloboration. However, to the best of our knowledge MR-TADF compounds containing nitrogen chelated boron are still unknown. Reported herein is a new class tetracoordinate boron-containing emitters bearing C^N^C- and N^N^N-chelating ligands. We demonstrate that replacement B-C covalent bond in C^N^C-chelating ligand by B-N...

New blue and blue‐green phosphorescent C^N chelate Pt(II) compounds that contain a dimesitylboryl‐functionalized phenyl‐1,2,3‐triazole ligand (Bptrz) are synthesized. The influence of three different ancillary ligands, namely acetylacetonato (acac), picolinate (pic) pyridyl‐1,2,4‐triazolyl (pytrz), on phosphorescence quantum efficiency excimer emission is examined. with p‐ Bptrz consistently emit color an wavelength = 490–500 nm while those m‐ λ em 450–460 as high 0.97. In addition to the...

Electron-rich and -poor BN-heterocycles with benzyl-pyridyl backbones two bulky aryls on the boron (Ar = tipp, BN-1, Ar MesF, BN-2) have been found to display distinct molecular transformations upon irradiation by UV light. BN-1 undergoes an efficient photoelimination reaction forming a BN-phenanthrene ΦPE 0.25, whereas BN-2 thermally reversible, stereoselective, quantitative isomerization dark colored BN-1,3,5-cyclooctatriene (BN-1,3,5-COT, BN-2a). This unusual photoisomerization persists...

A new class of deep blue electrophosphorescent Pt(II) emitters have been designed and synthesized. This employ tetradentate macrocyclic chelate chromophores to constrain the molecules in a non‐distorted flat geometry both ground state excited state. The do not produce excimer emission, with emission quantum efficiency as high 95% 10% doped PMMA (poly(methyl methacrylate) films, excellent UV stability, compared corresponding bidentate emitters. compounds are first examples fully sterically...

Abstract Naphthalene and acenaphthene with peri 2‐py BMes 2 (py=pyridyl, Mes=mesityl) substituents have been found to undergo facile phototransformation, cleavage of a C−C bond naphthalene, formation 2‐py‐bound benzoborepins as the major products. Mechanistic pathways this photoreaction established by examination both excited ground states using CASSCF CASPT2 methods in DFT time‐dependent calculations. The mesityl py‐naphthyl charge‐transfer transition migration from boron atom naphthyl...

A new class of brightly phosphorescent Pt(II) compounds that contain an N ∧ C‐chelate phenyl‐1,2,3‐triazolyl ligand (ptrz) and pyridyl‐1,2,4‐triazolyl (pytrz) in the central core is achieved. The impact various substituent groups on phosphorescence this molecules examined. Crystal structural analyses revealed has a great tendency to form stacked dimers—one which persistent even gas phase—leading excimer emission. introduction bulky substituents, such as diphenyl amino (NPh 2 ) or trityl (CPh...

Abstract Boranes with the general formula of HBR 2 have been found to undergo a facile 1,1‐hydroboration reaction pyrido[1,2‐a]isoindole ( A ), resulting in insertion BR unit into CN bond and formation variety BN heterocycles. Investigation on thermal reactivity heterocycles revealed that these molecules two distinct competitive elimination pathways: (or retro‐hydroboration) versus RH elimination, depending R group B atom chelate backbone. Mechanistic aspects highly unusual reactions...

Boron- and nitrogen (BN)-fused polycyclic aromatic frameworks with amine-directed formation of B-N covalent bonds have the potential to form a new family facile-synthesis multi-resonance luminophores, which, however, still face imperative challenges in diversifying molecular design narrow emission bandwidth tune colors. Here, we demonstrate strategic implementation bond containing polycyclo-heteraborin emitters wide-range colors from deep-blue yellow-green (442-552 nm), small full-width at...

C^C* chelated Pt(II) compounds that contain an N-heterocyclic carbene (NHC) donor have recently attracted great interest as blue or white phosphorescent emitters for organic light-emitting devices (OLEDs). To overcome the tendency excimer formation in compounds, α-duryl-β-diketonato ligand was selected ancillary compounds. Using this approach, a series of NHC-based has been designed and synthesized. The chelate ligands used new include 1-phenylimidazol-2-ylidene Pt1,...

Abstract Neuartige BN‐heterocyclische Verbindungen reagieren in einer doppelten Aren‐Photoeliminierung unter Bildung gelb fluoreszierender BN‐Pyrene mit zwei B‐N‐Einheiten. Bemerkenswert hierbei ist, dass die doppelte Aren‐Eliminierung auch durch elektrisch erzeugte Exzitonen elektrolumineszierenden (EL) Bauelementen gesteuert werden kann. Dies ermöglicht In‐situ‐Umwandlung von BN‐Heterocyclen im Festkörper und damit Verwendung BN‐Pyrenen als Emitter EL‐Bauelementen. Dieses Phänomen der...

B(npy)Ar2 (npy=2-(naphthalen-1-yl)pyridine) compounds bearing various nonbulky aryl groups undergo a clean and sequential two-step photoisomerization in which two substituents on boron migrate to carbon atom of the naphthyl moiety. The second isomerization step is first example reversible photoisoermization between borepin borirane. Both steric electronic factors have been found great impact this photoreactivity. Furthermore, borirane isomer reacts with oxygen, forming rare oxaborepin dimer.