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Materials with efficient circularly polarized phosphorescences (CPPs) are of potential use in advanced data encryption and anti-counterfeiting, bioimaging, optoelectronic devices and so forth. Herein, a simple method is presented for the preparations of CPP-active micro/nanocrystals with large luminescence dissymmetry factors (glum), high phosphorescence quantum efficiencies (Φp) and tunable emission colors. Diastereomeric IrIII and RuII complexes with chiral (±)-camphorsulfonate counter-anions are readily synthesized and assembled into crystalline microrods, microplates or nanofibers with ordered morphologies. The chir-ality information of chiral counter-anions is efficiently transferred to the metal components to afford CPPs with cyan, green, yellow, or red emission colors and ΦP in the range of 5%–85%. The number of chiral anions is found to play a role in influencing the CPP magnitudes of these crystals. The dicationic RuII and tricationic IrIII complexes show glum values in the 10−2 order, which are much larger with respect to those of monocationic IrIII complexes. Single crystal X-ray analysis is performed to obtain information on the chirality transfer of these materials. In addition, circularly polarized photonic signal waveguiding is demonstrated using the microcrystals of an IrIII complex. This work demonstrates an appealing strategy of constructing chiral micro/nano-architectures for potential applications in chiral nanophotonics. [ABSTRACT FROM AUTHOR]

Highlights: The single-atom Cu species with S = 0 spin ground state in CuIII-HHTP have been fabricated. The CuIII-HHTP exhibits remarkable performance with a high urea yield of 7.780 mmol h−1 g−1 with the corresponding Faradaic efficiency of 23.09% at − 0.6 V (vs. RHE). Low spin state and empty ( d x 2 -y 2 0 ) orbitals are favorable to enhance the production urea of C–N coupling process. The catalytic activities are generally believed to be relevant to the electronic states of their active center, but understanding this relationship is usually difficult. Here, we design two types of catalysts for electrocatalytic urea via a coordination strategy in a metal–organic frameworks: CuIII-HHTP and CuII-HHTP. CuIII-HHTP exhibits an improved urea production rate of 7.78 mmol h−1 g−1 and an enhanced Faradaic efficiency of 23.09% at − 0.6 V vs. reversible hydrogen electrode, in sharp contrast to CuII-HHTP. Isolated CuIII species with S = 0 spin ground state are demonstrated as the active center in CuIII-HHTP, different from CuII with S = 1/2 in CuII-HHTP. We further demonstrate that isolated CuIII with an empty d x 2 -y 2 0 orbital in CuIII-HHTP experiences a single-electron migration path with a lower energy barrier in the C–N coupling process, while CuII with a single-spin state ( d x 2 -y 2 1 ) in CuII-HHTP undergoes a two-electron migration pathway. [ABSTRACT FROM AUTHOR]

Designing catalyst to achieve ammonia synthesis at mild conditions is a meaningful challenge in catalysis community. Defective g-C3N4 nanosheet supported single-cluster ruthenium and iron catalysts were investigated for their ammonia synthesis performance. Based on density functional theory (DFT) calculations and microkinetic simulations, Ru3 single-cluster anchored on defective g-C3N4 nanosheet (Ru3/Nv-g-C3N4) has a turnover frequency (TOF) 5.8 times higher than the Ru(0001) step surface at industrial reaction conditions of 673 K and 100 bar for ammonia synthesis. In other words, similar TOFs could be achieved on Ru3/Nv-g-C3N4 at much milder conditions (623 K, 30 bar) than on Ru(0001) (673 K, 100 bar). Our computations reveal the reaction proceeds parallelly on Ru3/Nv-g-C3N4 through both dissociative and alternative associative mechanisms at typical reaction conditions (600–700 K, 10–100 bar); N-N bond cleavage of *N2 and *NNH from the two respective pathways controls the reaction collectively. With increasing temperatures or decreasing pressures, the dissociative mechanism gradually prevails and associative mechanism recedes. In comparison, Fe3/Nv-g-C3N4 catalyst shows a much lower catalytic activity than Ru3/Nv-g-C3N4 by two orders of magnitude and the reaction occurs solely through the dissociative pathway. The finding provides a prospective candidate and deepens the mechanistic understanding for ammonia synthesis catalyzed by single-cluster catalysts (SCCs). [ABSTRACT FROM AUTHOR]

Circularly polarized (CP) electroluminescence from organic light-emitting diodes (OLEDs) has aroused considerable attention for their potential in future display and photonic technologies. The development of CP-OLEDs relies largely on chiral-emitters, which not only remain rare owing to difficulties in design and synthesis but also limit the performance of electroluminescence. When the polarization (pseudospin) degrees of freedom of a photon interact with its orbital angular momentum, photonic spin-orbit interaction (SOI) emerges such as Rashba-Dresselhaus (RD) effect. Here, we demonstrate a chiral-emitter-free microcavity CP-OLED with a high dissymmetry factor (gEL) and high luminance by embedding a thin two-dimensional organic single crystal (2D-OSC) between two silver layers which serve as two metallic mirrors forming a microcavity and meanwhile also as two electrodes in an OLED architecture. In the presence of the RD effect, the SOIs in the birefringent 2D-OSC microcavity result in a controllable spin-splitting with CP dispersions. Thanks to the high emission efficiency and high carrier mobility of the OSC, chiral-emitter-free CP-OLEDs have been demonstrated exhibiting a high gEL of 1.1 and a maximum luminance of about 60000 cd/m2, which places our device among the best performing CP-OLEDs. This strategy opens an avenue for practical applications towards on-chip microcavity CP-OLEDs. Nanoscale circularly polarized light sources are an important building block for future integrated photonics. Here the authors demonstrate circularly polarized light emission from a thin organic single crystal light-emitting diode. [ABSTRACT FROM AUTHOR]

The preparation of multidimensional nano- and micro structures, in particular suprastructures with well-defined morphology and bright emissions, is a challenging task in supramolecular assembly. For this purpose, a new type of amphiphilic diplatinum complexes is presented as an excellent building block to assemble into highly phosphorescent nanofibers by supramolecular Pt⋯Pt interactions. These organoplatinum supramolecular fibers are further used as a pre-organized monomer reservior for the metal ion-triggered post-transformation into crystalline nanoneedles, nanorods, nanobunches, microplates, and microflowers with controllable morphology and bright phosphorescence. A reverse transformation of the obtained nanorods into nanofibers is demonstrated with the aid of ethylenediamine tetraacetic acid. In contrast, the direct treatment of diplatinum complexes with different metal ions fails to give well-defined nano and microstructures, suggestive of the pre-organized role of nanofibers for the morphological transformation. Preliminary applications of these nano- and suprastructures in sensing temperature and organic vapours by emission signal changes are demonstrated. In contrast to the conventional hierarchical assembly, the pre-organized monomer-reservoir strategy disclosed in this study offers a versatile method for the synthesis of organic nano and suprastructures with multidimensional morphology and controllable emission properties. [ABSTRACT FROM AUTHOR]