A hybrid organic–inorganic compound, (pyrrolidinium)MnBr3
, distinguished from rare earth (RE)‐doped inorganic perovskites, is discovered as a new member of the ferroelectrics family, having ...excellent luminescent properties and relatively large spontaneous polarization of 6 μC cm−2, as well as a weak ferromagnetism at about 2.4 K. With a quantum yield of >28% and emission lifetime >0.1 ms, such multiferroic photoluminescence is a suitable candidate for future applications in luminescence materials, photovoltaics, and magneto‐optoelectronic devices.
The separation of ethane (C2H6) from ethylene (C2H4) is of prime importance in the production of polymer-grade C2H4 for industrial manufacturing. It is very challenging and still remains unexploited ...to fully realize efficient C2H6/C2H4 separation in the emerging hydrogen-bonded organic frameworks (HOFs) due to the weak nature of hydrogen bonds. We herein report the benchmark example of a novel ultrarobust HOF adsorbent (termed as HOF-76a) with a Brunauer–Emmett–Teller surface area exceeding 1100 m2 g–1, exhibiting the preferential binding of C2H6 over C2H4 and thus highly selective separation of C2H6/C2H4. Theoretical calculations indicate the key role of the nonpolar surface and the suitable triangular channel-like pores in HOF-76a to sterically “match” better with the nonplanar C2H6 molecule than the planar C2H4, thus affording overall stronger multipoint van der Waals interactions with C2H6. The exceptional separation performance of HOF-76a for C2H6/C2H4 separation was clearly demonstrated by gas adsorption isotherms, ideal adsorbed solution theory calculations, and simulated and experimental breakthrough curves. Breakthrough experiments on HOF-76a reveal that polymer-grade ethylene gas can be straightforwardly produced from 50/50 (v/v) C2H6/C2H4 mixtures during the first adsorption cycle with a high productivity of 7.2 L/kg at 298 K and 1.01 bar and 18.8 L/kg at 298 K and 5.0 bar, respectively.
Highly phosphorescent (Ph4P)2MnBr4 as a low‐cost and environmentally benign emitting material achieves peak current efficiency of 25.4 cd A−1 and external quantum efficiency (EQE) of 7.2% for ...nondoped organic light‐emitting diodes, and peak current efficiency of 32.0 cd A−1 and EQE of 9.6% for doped devices with 20% (Ph4P)2MnBr4:27% TCTA:53% 6DCZPPY as a doping emitting layer.
As low‐dimensional lead‐free hybrids with higher stability and lower toxicity than those of three‐dimensional lead perovskites, organic antimony(III) halides show great application potential in ...opt‐electronic field owing to diverse topologies along with exceptional optical properties. We report herein an antimony(III) hybrid (MePPh3)2SbCl5 with a zero‐dimensional (0D) structure, which exhibits brilliant orange emission peaked at 593 nm with near‐unity photoluminescent quantum yield (99.4 %). The characterization of photophysical properties demonstrates that the broadband emission with a microsecond lifetime (3.24 μs) arises from self‐trapped emission (STE). Electrically driven organic light‐emitting diodes (OLEDs) based on neat and doped films of (MePPh3)2SbCl5 were fabricated. The doped devices show significant improvement in comparison to non‐doped OLEDs. Owing to the much improved surface morphology and balanced carrier transport in light‐emitting layers of doped devices, the peak luminance, current efficiency (CE) and external quantum efficiency (EQE) are boosted from 82 cd m−2 to 3500 cd m−2, 1.1 cd A−1 to 6.8 cd A−1, and 0.7 % to 3.1 % relative to non‐doped devices, respectively.
A highly luminescent organic antimony(III) hybrid (MePPh3)2SbCl5 featured with STE emission is prepared with good reproducibility and high stability. High‐efficiency OLEDs are demonstrated with this hybrid as an emitter with the luminance of 3500 cd m−2, current efficiency of 6.8 cd A−1 and EQE of 3.1 %, respectively.
Luminescence of ferroelectric materials is one important property for technological applications, such as low-energy electron excitation. However, the vast majority of doped inorganic ferroelectric ...materials have low luminescent efficiency. The past decade has envisaged much progress in the design of both ferroelectric and luminescent organic–inorganic hybrid complexes for optoelectronic applications. The combination of ferroelectricity and luminescence within organic–inorganic hybrids would lead to a new type of luminescent ferroelectric multifunctional materials. We herein report a hybrid molecular ferroelectric, (pyrrolidinium)MnCl3, which exhibits excellent ferroelectricity with a saturation polarization of 5.5 μC/cm2 as well as intense red luminescence with high quantum yield of 56% under a UV excitation. This finding may extend the application of organic–inorganic hybrid compounds to the field of ferroelectric luminescence and/or multifunctional devices.
Fano Resonance in Single‐Molecule Junctions Zheng, Yan; Duan, Ping; Zhou, Yu ...
Angewandte Chemie International Edition,
October 4, 2022, Letnik:
61, Številka:
40
Journal Article
Recenzirano
The Fano resonance in single‐molecule junctions could be created by interaction with discrete and continuous molecular orbitals and enables effective electron transport modulation between ...constructive and destructive interference within a small energy range. However, direct observation of Fano resonance remains unexplored because of the disappearance of discrete orbitals by molecule‐electrode coupling. We demonstrated the room‐temperature observation of Fano resonance from electrochemical gated single‐molecule conductance and current–voltage measurements of a para‐carbazole anion junction. Theoretical calculations reveal that the negative charge on the nitrogen atom induces a localized HOMO on the molecular center, creating Fano resonance by interfering with the delocalized LUMO on the molecular backbone. Our findings demonstrate that the Fano resonance in electron transport through single‐molecule junctions opens pathways for designs of interference‐based electronic devices.
This work offers the first direct observation of the Fano resonance effect in single‐molecule junctions by the charge injection on the nitrogen atom using an EC‐STM‐BJ technique at room temperature, which provides a facile way to manipulate electron tunneling in the single‐molecule junctions and opens a new avenue toward the design of interference‐based molecular electronic devices.
An elaborately designed pyridinium‐functionalized octanuclear zinc(II) coordination container 1‐Zn was prepared through the self‐assembly of Zn2+, p‐tert‐butylsulfonylcalix4arene, and ...pyridinium‐functionalized angular flexible dicarboxylate linker (H2BrL1). The structure was determined by a single‐crystal X‐ray diffractometer. 1‐Zn displays highly sensitive and specific recognition to 2‐picolylamine as revealed by drastic blueshifts of the absorption and emission spectra, ascribed to the decrease of intramolecular charge transfer (ICT) character of the container and the occurrence of intermolecular charge transfer between the host and guest molecules. The intramolecular charge transfer plays a key role in the modulation of the electronic properties and is tunable through endo‐encapsulation of specific guest molecules.
Coordination containers: An octanuclear zinc(II) coordination container incorporating both electron‐rich sulfonycalixarene and electron‐deficient pyridinium‐dicarboxyalte ligands shows highly sensitive and specific recognition to 2‐picolyamine derivatives due to strong host–guest interactions (see figure).
Square‐planar bis(σ‐fluorophenylacetylide) platinum(II) complexes Pt(Me3SiCCbpyCC‐SiMe3)(CCC6H4F)2 (CCC6H4F‐2 for 2, CCC6H4F‐3 for 3, and CCC6H4F‐4 for 4; ...Me3SiCCbpyCCSiMe3=5,5′‐bis(trimethylsilylethynyl)‐2,2′‐bipyridine) were prepared and were characterized by spectroscopic and luminescence studies, and X‐ray crystallography. The color and luminescence of crystalline complex 3 is specifically sensitive to CHCl3 vapor to afford 140–180 nm of luminescence vapochromic redshift, which is useful for specific detection of CHCl3 vapor. Complex 4 displays selective luminescence vapochromic properties to CH2Cl2 and CHCl3 vapors with a luminescence vapochromic shift response of ca. 150–200 nm. Interestingly, complexes 2–4 exhibit reversible, and naked‐eye perceivable, mechanical stimuli‐responsive color and luminescence changes. When solid species 2–4 are crushed gently or ground, the crystalline state is converted to an amorphous phase. Meanwhile, bright yellow‐orange luminescence in the crystalline species is converted to dark red under UV light irradiation with 100–160 nm of mechanochromic shift response. A vapochromic or mechanochromic cycle was monitored by dynamic variations in emission spectra and X‐ray diffraction (XRD) patterns. The halohydrocarbon vapor‐ or mechanical‐grinding‐triggered color and luminescence switches are most likely correlated to a shorted intermolecular Pt–Pt distance as that revealed in vapochromic species 4⋅0.5 CH2Cl2 by X‐ray crystallography, thus leading to an increased contribution from intermolecular Pt–Pt interaction as demonstrated by DTF computational studies.
All change please: Planar bis(σ‐fluorophenylacetylide)platinum(II) complexes exhibit mechanical stimuli‐responsive color and luminescence changes and specifically selective luminescence vapochromic response to CHCl3/CH2Cl2 vapor due to an increased contribution from intermolecular Pt–Pt interactions (see graphic).
Investigating the correlations of electron transport between multiple channels shows vital promises for the design of molecule‐scale circuits with logic operations. To control the electron transport ...through multiple channels, the modulation of electronegativity shows an effective frontier orbit control method with high universality to explore the interactions between transport channels. Here, two series of compounds with a single nitrogenous conductive channel (Sg) and dual‐channels (Db) are designed to explore the influence of electronegativity on electron tunneling transport. Single‐molecule conductance measured via the scanning tunneling microscope break junction technique (STM‐BJ) reveals that the conductance of Db series is significantly suppressed as the electronegativity of nitrogen becomes negative, while the suppression on Sg is less obvious. Theoretical calculations confirm that the effect of electronegativity extends to a dispersive range of molecular frameworks owing to the delocalized orbital distribution from the dual‐channel structure, resulting in a more significant conductance suppression effect than that on the single‐channel. This study provides the experimental and theoretical potentials of electronegativity gating for molecular circuits.
The modulation of the electron transport in multiple conducting channels influenced by the electronegativity variation is evaluated by electronegativity tuning on single‐ (Sg series) and dual‐channel (Db series) nitrogenous compounds. This work explores the electron transport mechanism in nitrogenous molecules with different channels and electronegativity, paving the way for designing integrated molecular devices for electronics and nanotechnology.
The reactions of MnBr2 and ethane-1,2-diylbis(diphenylphosphine oxide) (dppeO2) in dichloromethane–methanol solutions gave colorless crystals with the general chemical formulas MnBr2(dppeO2) n (1), ...MnBr2(dppeO2)(DMF) n (1a), Mn(dppeO2)3MnBr4 (2), and Mn2Br4(dppeO2)2 (3) depending on the crystallization conditions. Compounds 1 and 1a display one-dimensional chain structures composed of Mn(II) ions linked by bridging dppeO2 to exhibit tetrahedral (1) or trigonal-bipyramidal (1a) coordination geometry, whereas 3 exhibits a cyclic dinuclear structure with two Mn(II) centers bridged by double dppeO2 to adopt tetrahedral geometry. Compound 2 consists of octahedrally coordinated cation Mn(dppeO2)32+ and tetrahedrally arranged anion MnBr42–. While 1 and 3 in crystalline and powder states are highly luminescent with green emission bands centered at ca. 510 nm, 2 shows intense orange luminescence peaking at 594 nm. Upon exposure of 1 to N,N-dimethylformamide vapor, the green emission centered at 510 nm is converted to red luminescence peaking at 630 nm, ascribed to the formation of DMF-coordinated compound 1a with a trigonal-bipyramidal ligand field, as demonstrated by X-ray crystallography. Red-emitting 1a could be reverted to the original green-emitting 1 with a tetrahedral ligand field upon heat at 160 °C, and such a reversible conversion could be perfectly repeated for several cycles. A new mechanism of luminescent vapochromism is thus proposed because of the reversible conversion of ligand fields in manganese(II) complexes.
