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A novel direct construction of C–N bonds for efficient synthesis of diverse quinoxalines by α-imino radicals.

More and more luminescent lead-free metal halides containing Cu(i), Mn(ii), Sb(iii), Sn(ii) and rare-earth halides are developed toward highly efficient electrically-driven light emitting diodes.

Understanding the impact of substituents on the quantum interference effect at single molecule scale is of great importance for the design of molecular devices. In this work, three platinum(II) complexes with -H, -NH2 and -NO2 groups on conductive backbones were designed and synthesized. Single-molecule conductance, which was measured using scanning tunnelling microscope break junction (STM-BJ) technique, demonstrated a conductance freeze phenomenon under the variation of substituents. Theoretical study revealed that, despite the electronic effect of the substituents shifting the energy level of molecular orbital, the quantum interference effect vanished the influence of electronic effect on the conductance and eventually leaded to the conductance freeze.

The construction of distorted or irregular coordination polyhedrons with specific shapes and functionalities is highly challenging. Here, we demonstrate a viable strategy for attaining a severely d...

Acetic acid probes based on Zinc complexes with high stability and selectivity were successfully prepared by reacting the H2tBuCarPy ligand with ZnBr2, which exhibit reversible vapor-chromism during the uptake and release of acetic acid.

Triphosphine-supported PtAu2 complexes were elaborately designed using 4-substituted phenylacetylide ligands with electron-rich N,N′-diarylamine groups to manifest high-efficiency red electroluminescence.

Direct α-C(sp3)–H alkylation of hydroaminoalkylation (HAA) catalyzed by tBuOK/DMSO/O2 from α-aryl benzylamines with styrenes is reported.

A metal-free intramolecular C(sp2)–H/N–H amination between pyridines and arylamines is realized, which provides efficient access to α-carbolines. This methodology exhibits excellent applicability and, thus, holds attractive application potential.

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.

In this work, the synthesis, characterization, and phosphorescent properties of the coordination polymer, {Ag3(dppy)2[μ-SCN]3}n (1), are described. X-ray crystallography showed that the complex forms a one-dimensional infinite zipper-like chained structure linked by thiocyanate as the bridging ligand. The silver(I) complex exhibits a strong sky-blue phosphorescence with a high quantum yield of 70.2% in the solid state at ambient temperature. Additionally, following a temperature change from 418 to 77 K, the complex displays a remarkable luminescent thermochromic property. A novel 1D zipper-like silver(I) coordination polymer is constructed by 2-diphenylphosphinopyridine and thiocyanate. It exhibits strong sky-blue phosphorescence with high quantum yield of 70.2% in solid state at ambient temperature. Furthermore, its reversible thermochromism is demonstrated.

Photoactive metal ions doping is an efficient way to modulate the photophysical properties of perovskite. Herein, we report a zero-dimensional (0D) InCl6(C4H10SN)4·Cl:Sb3+ by doping Sb3+ into InCl6(C4H10SN)4·Cl, which undergoes a significant enhancement of the emission peak at 550 nm with photoluminescence quantum yield boosting from 20% to 90%. Interestingly, a red-shifted emission is observed on InCl6(C4H10SN)4·Cl:Sb3+ upon exposure to ethanol and DMF vapor with the emission peak red-shifted from 550 to 580 and 600 nm, respectively. Furthermore, the transformation is reversed after drying the vapor-exposed InCl6(C4H10SN)4·Cl:Sb3+ at ambient conditions. Detailed characterizations reveal that the crystal packing and structure distortion account for the reversible luminescent vapochromism. Thanks to the superior stability and feasible transformation of InCl6(C4H10SN)4·Cl:Sb3+ at ambient conditions, a DMF sensor was fabricated by coating the mixture of InCl6(C4H10SN)4·Cl:Sb3+ and PMMA into patterned substrate, which exhibits an obvious luminescent change upon release and uptake of DMF and excellent stability and producibility in several cycles.

Highly soluble d8-d10 heteronuclear phosphors afford an alternative approach to achieve high-efficiency organic light-emitting diodes (OLEDs) through a solution process. In this work, four highly phosphorescent d8-d10 heteronuclear complexes with significant Pt-Au interactions were prepared. By judicious selection of sterically hindered and π-conjugated substituents in triphosphine ligands, the phosphorescence is dramatically promoted through effectively prohibiting nonradiative thermal relaxation with an efficiency of 0.94-0.99 in doping films. Exploiting highly emissive Pt-Au complexes as phosphorescent dopants, ultrahigh-efficiency solution-processed OLEDs were attained. The peak current efficiency, power efficiency, and external quantum efficiency are 96.2 cd A-1, 65.0 lm W-1, and 26.4% for the green-emitting PtAu2 phosphor and 68.6 cd A-1, 42.5 lm W-1, and 25.1% for the orange-emitting Pt2Au phosphor, which represent the state-of-art for solution-processed OLEDs based on non-iridium phosphors.

In the present study, 2,6-bis(diphenylphosphino)pyridine ((Ph2P)2py)-supported cis- and trans-Pt2Ag2 alkynyl complexes were prepared and characterized by X-ray crystallography. Although the cis-Pt2Ag2 complexes are slightly emissive at ambient conditions, the trans-Pt2Ag2 complexes exhibit moderate photoluminescence in dichloromethane and have strong emission in the solid state, originating from aromatic acetylide to (Ph2P)2py ligand-to-ligand charge transfer (3LLCT) and Pt2Ag2 cluster metal-centered (3MC) triplet states. Remarkably, the trans-Pt2Ag2 complex [Pt2Ag2{(Ph2P)2py}2(CCC6H5)4](SO3CF3)2 exhibit remarkable luminescent vapochromism with emission red-shifts of 100 nm in response to MeCN vapor, arising from intramolecular structural conversion from staggered to parallel arrangements of two face-to-face Pt(CCC6H5)2 moieties, which results in the alteration of the excited-state energy in the solid state as supported by TD-DFT studies.

High color purity with narrow-band emission is a key factor for full-color displays. However, phosphorescent metal complexes typically exhibit broad emission with a full width at half maxima (FWHM) in the range of 80–100 nm. Here, we demonstrate a facile approach to achieve narrow-band emission by introducing electron-deficient moieties with electron-transport character into PtAg2 heteronuclear complexes. The as-synthesized PtAg2 complex 3 with dibenzo[b,d]thiophene 5,5-dioxide-3-acetylide shows extremely narrow emission with an FWHM of 25 nm in CH2Cl2 solution. The narrow-band emission is further verified by another two PtAg2 complexes containing electron-transport units such as oxadiazole (complex 4) and triphenyl-triazine (complex 5), in which the FWHM values are 26 nm for 4 and 28 nm for 5 in CH2Cl2 solution. TD-DFT studies suggest that the involvement of intra-ligand transition within an electron-deficient acetylide ligand is likely responsible for the narrow-band emission. Solution-processed OLEDs based on complex 4 exhibit excellent device performance with an FWHM of 37 nm in the electroluminescent spectrum and the highest current efficiency (CE) of 69.5 cd A−1, power efficiency (PE) of 50.5 lm W−1 and external quantum efficiency (EQE) of 18.2%. The narrow-band electroluminescence is also attained in complexes 3 and 5 with the FWHM values of 31 and 40 nm, respectively, which represent the narrowest electroluminescence for multinuclear metal complexes. This strategy of introducing electron-transport moieties not only improves the device performance but also narrows the emission width and thus enhances the color purity.

A dpppy-protected (dpppy = 2,6-bis(diphenylphosphino)pyridine) d10–d10 heterooctanuclear cluster complex [Ag3Cu5(ebzcz)6(dpppy)3](ClO4)2 (Hebzcz = 1-(3,6-di-tert-butylcarbazol-9-yl)-4-ethynylbenzene) was prepared by self-assembly reaction and characterized by single crystal X-ray diffraction. The diphosphine-supported Ag3Cu5 cluster structure is highly stabilized through substantial Cu–Ag and Cu–Cu intermetallic interactions. Since the Ag3Cu5 cluster is sufficiently shielded by bulky ligands (three ebzcz and three dpppy), thermally non-radiative relaxation is strongly prohibited so as to give brilliant photoluminescence under ambient conditions. As revealed by TD-DFT studies, the luminescence arises from metal cluster-centred 3[d → p/s] and 3[π (ebzcz) → π* (dpppy)] 3LLCT (ligand-to-ligand charge transfer) transitions. Taking advantage of Ag3Cu5 cluster complex as a phosphorescent dopant, a high-efficiency solution-processed organic light-emitting diode is achieved with a peak current efficiency of 38.1 cd A−1, a power efficiency of 29.9 lm W−1 and an external quantum efficiency of 14.7%.

Circular polarized luminescence (CPL)-active materials attract great attentions owing to their widely applications in 3D optical displays and encrypted transmission. Inspired by the strategies adopted in perovskite based CPL materials, herein, CPL-active hybrids (D)- and (L)-(tert-butyl prolinate)MnCl

In this work, rational design of highly soluble and phosphorescent Ag–Au cluster complexes with exceptional [2]catenane structures is conducted using 1,8-diethynyl-9H-carbazole (H3decz) as a rigid ...

Metal-organic frameworks (MOFs) with cuprous-halide-aggregates have shown superiority as organic LED (OLED) and semiconductor materials, while engineering MOF flexibility by involving the expansion of cuprous aggregates remains a great challenge. In this particular work, a dissolution-recrystallization structural transformation (DRST) with the dramatic growth of CuI-I aggregates, from 2D NJNU-100 to 3D NJNU-101 has been successfully realized. The unsaturated coordination nodes (2-positional nitrogen atoms) in NJNU-100 have been demonstrated to be the driven force for DRST to NJNU-101 via the formation of coordination bonds. The structural transformation process was irreversible and observed with optical microscopy and powder XRD. The expansion of CuI-I aggregates was also computational simulated accompanying with the rotation of the neutral tripodal TTTMB ligand (1,3,5-tris(1,2,4-triazol-1-ylmethyl)-2,4,6-trimethylbenzene) and the reduction of CuII to CuI. Moreover, the intermediate product NJNU-102 was captured by adding the planar molecular anthrancene to shut down the reaction, where only partial 2-positional nitrogen atoms coordinated to the aggregates and the anthrancene was oxidized to anthraquinone. NJNU-102 has further confirmed that DRST involved the breakage and recombination of coordination bonds and the electron transfer. NJNU-100 and NJNU-101 could be applied as semiconductor and OLED materials. This work has provided insights for crystal engineering, especially for the construction of the CuIxXy aggregates, and illustrated that DRST could be controlled with a rational design (as the unsaturated coordination modes).

Seeking the strategies of designing highly conductive molecular structures is one of the core researches in molecular electronics. As asymmetric structure has manifested feasible properties in comprehensive fields, we introduce the structures of asymmetric platinum(II) complexes into the charge transport study at single-molecule scale for the first time. The single-molecule conductance measurement results reveal that, in platinum(II)-aryloligoynyl structures, the conductance of asymmetrically coordinated complexes is obviously higher than that of the symmetric isomers with the same molecular length, while the conductance is almost identical in symmetric and asymmetric platinum(II)-oligoynyl complexes. Theoretical study uncovers that, upon connecting to the oligoynyl structure, the aromatic group effectively extends the π-system of the whole conductive backbone and gathers the HOMO population mainly on the longer oligoynyl ligand, which reduces the energy barrier in electron transport and enhances the conductance through HOMO energy lifting. This result provides feasible strategy for achieving high conductive molecular devices.

Fabricating electron transport layers at low temperatures is challenging but highly desired in the field of flexible perovskite solar cells (f-PSCs). In this study, highly uniform cerium oxide (CeOx) films prepared by the UV–O3 treatment have been successfully applied as the electron transport layer (ETL) in methylammonium lead halide (CH3NH3PbI3) perovskite-based f-PSCs. Under AM 1.5 G sunlight with 100 mW cm−2, these cells exhibited an open-circuit voltage (Voc) of 0.98 V, a short-circuit current density (Jsc) of 19.42 mA cm−2, a fill factor (FF) of 0.72 and power conversion efficiency (PCE) of 14.63%. The PCE was much higher than that of the control planar CeOx ETL (PCE ∼ 9.08%) prepared at a low temperature (80 °C) without the UV–O3 treatment, and this was ascribed to the improved CeOx film, enhanced light absorption and suppressed charge recombination. The cells that bend at 15 mm of radius showed excellent stability with less than 10% reduction in PCE after 500 cycles of repeated bending at ambient temperature. The charge-transmission kinetic parameters and long-term stability of the CeOx-based f-PSCs were analyzed as well.

A triphosphine-supported Pt2Cu heterotrinuclear complex (1) constrained with 3,6-di-tert-butyl-1,8-diethynyl-9H-carbazole exhibits two-step phosphorescent mechanochromism due to intramolecular deformation. The stepwise phosphorescent mechanochromism following green → yellow → orange-red corresponds exactly to the phosphorescent emission observed in crystal morphs 1·4THF (green), 1·3acetone (yellow), and 1·4CH2Cl2 (orange-red), respectively, with different degrees of intramolecular deformation, as demonstrated by X-ray crystallography.

We describe herein a viable approach to enhance phosphorescence efficiency in PtCu2 complexes with aromatic acetylides by the use of bis(di-2-tolylphosphinomethyl)phenylphosphine (dTolmp) in place of bis(diphenylphosphinomethyl)-phenylphosphine (dpmp) as a supporting ligand. Relative to dpmp-supported PtCu2 complexes, dTolmp-supported complexes having the same acetylide ligands show not only a 16–36 nm red-shift of the emission peaks, but also a dramatic phosphorescence enhancement. The phosphorescence quantum yields of dTolmp-supported PtCu2 complexes are boosted to 6.6 and 11.6 times as high as those of the dpmp-supported ones in CH2Cl2 solutions and the solid state, respectively. From dpmp to dTolmp, introducing sterically hindered 2-methyl groups to phenyl rings not only improves the π-conjugation character of PtCu2 complexes, but also effectively inhibits the deactivation process of the triplet excited state through non-radiative relaxation. The phosphorescence properties were systematically modulated in a wide spectral range from 502 to 672 nm by introducing electron-donating or electron-withdrawing substituents into aromatic acetylides.

Two heteroctanuclear Au

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 )2 SbCl5 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 )2 SbCl5 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.

Through elaborate ligand design to create knotted structures with specific topologies is a major challenge for chemists. In this work, the self-assembly between U-shape 3,6-di-tert-butyl-1,8-diethynyl-9H-carbazole (H2L) and Au+ through gold(I)-bis(acetylide) linkages under π-bonded Cu+ template gives rise to complex 1 with two interlocked metallostrands as well as complexes 3 (n = 3) and 4 (n = 4) with [(AuL)n]n- metallostrands showing trefoil knot topology. Upon incorporating two [Au(dppb)Au]2+ (dppb = Ph2P(CH2)4PPh2) moieties through bis(Au-acetylide) coordination bonds, the interlocked structure (1) is fully closed to form a figure-eight knotted structure in complex 2. The folding and threading of metallocyclic strings are directed by Cu+, which are π-ligated to two or three acetylides to generate double-folding or triple-folding cross points. Complexes 1-4 show intense phosphorescence in both solutions and solid states at ambient temperature, originating from admixture of metal centered 3[d®p/s], 3IL (intraligand), and 3[p (L) ® s/p (Au/Cu)] 3LMCT triplet states.

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.

Bis(diphenylphosphinomethyl)phenylphosphine (dpmp)-supported Pt2Au heterotrinuclear complexes [Pt2Au(dpmp)2(C≡CPh)4](ClO4) (1), [Pt2Au(dpmp)2(DEBf)(C≡CPh)2](ClO4) (2), and [Pt2Au(dpmp)2(DECz)(C≡CPh)2](ClO4) (3) were prepared and used in organic light-emitting diodes (OLEDs) as a new class of light emitters, where DEBf = dibenzofuran-4,6-diacetylide and DECz = 3,6-di-tert-butylcarbazole-1,8-diacetylide. Although the flexible structure of Pt2Au complex 1 (λem = 503 nm, Φem < 0.1%) results in weak photoluminescence in fluid CH2Cl2, complexes 2 (λem = 585 nm, Φem = 4.9%) and 3 (λem = 589 nm, Φem = 3.2%) with a rigid conformation give a much stronger phosphorescence. The displacement of two σ-bonded phenylacetylide ligands with a diacetylide ligand such as DEBf and DECz to fasten Pt2Au structures facilitates greatly luminescent emission so that the emissive quantum yield in doping film is as high as 89% for 2 and 93% for 3. As revealed by a theoretical study, the severe structural distortion of diacetylide-linked Pt2Au complexes 2 (λem = 585 nm) and 3 (λem = 589 nm) in a triplet excited state gives rise to significant red shifts of phosphorescent emission spectra relative to that of complex 1 (λem = 503 nm). By means of Pt2Au complexes as phosphorescent emitters, solution-processed OLEDs achieved a relatively low external quantum efficiency (EQE < 9.5%) when commercial poly(ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) was used as the hole-injection layer (HIL). In contrast, the peak EQE was increased to 18.3% with a dramatic increase of efficiency by the use of modified HILs composed of PEDOT:PSS and PSS-Na, which provide a higher work function and a better film morphology.

To unveil the influence of metal coordination on charge transport and length-dependent conductance attenuation in π-conjugated organic molecules, trans-Ru(dppe)2 (dppe = 1,2-bis(diphenylphosphino)ethane) was implanted into oligoynyl chains with various number of ethynyl groups to construct Au–molecule–Au junctions using methylthiol (−SMe) as anchoring groups. The single-molecule conductance measured by I(s) method gave high and low values of conductance. A direct comparison of the conductance indicates that implanting trans-Ru(dppe)2 moiety into π-conjugated oligoynyl chains results in 2.6- to 5.8-fold enhancement of the conductance although the molecular length is increased by ca. 0.25 nm as a result of Ru insertion. More importantly, implanting trans-Ru(dppe)2 moiety into π-conjugated oligoynyl chains alleviates dramatically length-dependent conductance attenuation in view of the much smaller conductance decay constants for ruthenium(II)-implanted molecules (2.6 nm–1 for high value and 2.5 nm–1 for low ...