Two-dimensional honeycomb molecular networks confine a substrate’s surface electrons within their pores, providing an ideal playground to investigate the quantum electron scattering phenomena. ...Besides surface state confinement, laterally protruding organic states can collectively hybridize at the smallest pores into superatom molecular orbitals. Although both types of pore states could be simultaneously hosted within nanocavities, their coexistence and possible interaction are unexplored. Here, we show that these two types of pore states do coexist within the smallest nanocavities of a two-dimensional halogen-bonding multiporous network grown on Ag(111) studied using a combination of scanning tunneling microscopy and spectroscopy, density functional theory calculations, and electron plane wave expansion simulations. We find that superatom molecular orbitals undergo an important stabilization when hybridizing with the confined surface state, following the significant lowering of its free-standing energy. These findings provide further control over the surface electronic structure exerted by two-dimensional nanoporous systems.
A new class of diamino‐substituted π‐extended phenazine compound was synthesized, and its photophysical properties were investigated. The U‐shaped diaminophenazine displayed photoluminescence in ...solution with moderate quantum yield. The diamino aromatic compound was found applicable to the poly‐condensation with formaldehyde to form Tröger's base ladder polymer. The obtained microporous ladder polymer features high CO2 adsorption selectivity against N2, most likely due to the presence of basic nitrogen atoms in the phenazine rings.
A new aminophenazine functional molecule: It displays efficient photoluminescence and positive luminochromism in organic solvent. Not only useful it is as luminophore, but also does it serve as a building block for Tröger's base regioregular ladder polymer. The ladder polymer nicely shows reversible adsorption/desorption behavior of carbon dioxide molecule.
A new thermally activated delayed fluorescence (TADF) compound based on a donor-acceptor (D-A) architecture (D = phenoxazine; A = dibenzo
phenazine) has been developed, and its photophysical ...properties were characterized. The D-A compound is applicable as an emitting material for efficient organic light-emitting diodes (OLEDs), and its external quantum efficiency (EQE) exceeds the theoretical maximum of those with prompt fluorescent emitters. Most importantly, comparative study of the D-A molecule and its D-A-D counterpart from the viewpoints of the experiments and theoretical calculations revealed the effect of the number of the electron donor on the thermally activated delayed fluorescent behavior.
The photophysics of a thermally activated delayed fluorescence (TADF) emitting macrocycle consisting of two dibenzoa,jphenazine acceptor moieties bridged by two N,N,N’,N’‐tetraphenylene‐1,4‐diamine ...donor units was scrutinized in solution by steady‐state and time‐resolved spectroscopy. The fluorescence lifetime of the compound proved to be strongly solvent‐dependent. It ranges from 6.3 ns in cyclohexane to 34 ps in dimethyl sulfoxide. In polar solvents the fluorescence decay is predominantly due to internal conversion. In non‐polar ones radiative decay and intersystem crossing contribute. Contrary to the behaviour in polymer matrices (S. Izumi et al., J. Am. Chem. Soc. 2020, 142, 1482) the excited state decay is not predominantly due to prompt and delayed fluorescence. The solvent‐dependent behaviour is analyzed with the aid of quantum chemical computations.
Using steady‐state and transient absorption spectroscopy as well as quantum chemical calculations, the depicted TADF macrocycle is investigated. It features strongly solvent‐dependent S1 lifetimes and concomitantly triplet yields. While embedded in matrix environments the TADF character is evident, in solution these properties are lost.
In this work, we present how a small change in molecular structure can affect the electrochemical stability of organic compounds. A new electron donor‐acceptor‐donor‐acceptor (D‐A‐D‐A) macrocyclic ...π‐conjugated compound (tBuMC) comprising of dibenzophenazine as As and N,N’‐bis(t‐butylphenyl)‐p‐phenylenediamines as Ds has been synthesized. The photophysical investigation uncovered that tBuMC showed thermally activated delayed fluorescence and that the organic light‐emitting diodes (OLEDs) fabricated with tBuMC as the emitter achieved high external quantum efficiency (EQEs) of ca. 10%. However, the OLED with tBuMC showed a slightly lower EQE than that of the OLED with MC (11.6%) and showed greater EQE roll‐off. Comparative studies on electrochemical properties of tBuMC, MC, and a linear analogue (Linear) revealed the introduction of t‐Bu groups in the D‐A‐D‐A scaffold causes a significant change in redox behavior. Full electrochemical and spectroelectrochemical studies gave clues to understand how the steric hindering group is affecting the charge distribution in the new molecules which results in a significant difference in the OLED roll‐off. The electrochemical investigations together with UV‐Vis‐NIR and EPR analyses supported by quantum chemical theoretical calculations were performed, which provided us insights on the effect of structural modification on the redox properties of the D‐A‐D‐A scaffold.
A new derivative of purely‐organic thermally activated delayed fluorescent macrocyclic compound has been synthesized. Comparative studies on the electrochemical and photophysical properties of the compound and its parent compound and a linear analogue have been investigated. Slight structural modification of the macrocycle caused a significant difference in the EQE roll‐off of the OLED devices. Further experiments and theoretical calculations revealed the effect of the structural modification on the properties and EQE roll‐off.
A new class of thermally activated delayed fluorescent donor–acceptor–donor–acceptor (D–A–D–A) π-conjugated macrocycle comprised of two U-shaped electron-acceptors (dibenzoa,jphenazine) and two ...electron-donors (N,N′-diphenyl-p-phenyelendiamine) has been rationally designed and successfully synthesized. The macrocyclic compound displayed polymorphs-dependent conformations and emission properties. Comparative studies on physicochemical properties of the macrocycle with a linear surrogate have revealed significant effects of the structural cyclization of the D–A-repeating unit, including more efficient thermally activated delayed fluorescence (TADF). Furthermore, an organic light-emitting diode (OLED) device fabricated with the macrocycle compound as the emitter has achieved a high external quantum efficiency (EQE) up to 11.6%, far exceeding the theoretical maximum (5%) of conventional fluorescent emitters and that with linear analogue (6.9%).
A new class of diamino‐substituted π‐extended phenazine compound was synthesized, and its photophysical properties were investigated. The U‐shaped diaminophenazine displayed photoluminescence in ...solution with moderate quantum yield. The diamino aromatic compound was found applicable to the poly‐condensation with formaldehyde to form Tröger's base ladder polymer. The obtained microporous ladder polymer features high CO2 adsorption selectivity against N2, most likely due to the presence of basic nitrogen atoms in the phenazine rings.
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![3,11‐Diaminodibenzo[a,j]phe...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0947-6539_1521-3765/small "3,11‐Diaminodibenzo[a,j]phenazine: Synthesis, Properties, and Applications to Tröger's Base‐Forming Ladder Polymerization")
