Using bromoantimonate (V) (N‐EtPy)SbBr6 as an example, it is demonstrated that ABX6 compounds can form perovskite‐like 3D crystalline frameworks with short interhalide contacts, enabling advanced ...optoelectronic characteristics of these materials. The designed compound shows an impressive performance in planar junction solar cells delivering external quantum efficiency of ≈80% and power conversion efficiency of ≈4%, thus being comparable with the conventional perovskite material MAPbBr3. The discovery of the first perovskite‐like compound ABX6 exhibiting good photovoltaic performance opens wide opportunities for rational design of novel perovskite‐like semiconductor materials for advanced electronic and photovoltaic applications.
Planar junction solar cells based on the complex antimony (V) bromide (N‐EtPy)SbBr6 reveal external quantum efficiency of ≈80% and power conversion efficiency of ≈4%. The discovery of the first perovskite‐like compound ABX6 exhibiting good photovoltaic performance opens wide opportunities for rational design of novel hybrid semiconductor materials for advanced electronic and photovoltaic applications.
We report on W-band EPR and quantum chemical investigation of novel organic tetraradicals with negative axial zero-field splitting (ZFS) parameter D. These belong to the class of quintet ...1,3,5-tribromophenylene-2,4-dinitrenes bearing different substituents in position 6 of the benzene ring (1b, N3; 1c, F; 1d, CN; 1e; Cl; 1f, Br). Analysis of the W-band EPR spectrum of dinitrene 1c reveals its large negative ZFS parameter D = −0.27 cm–1. Quantum chemical calculations show that negative D gradually grows in the row of 1c(F) < 1b(N3) < 1d(CN) < 1e(Cl) < 1f(Br) dinitrenes due to decreasing of the through-space distance between the nitrene units and neighboring bromine atoms. Shorter steric N···Br distance results in the stronger contribution of the spin–orbit coupling (SOC) to the total ZFS. The sign of D depends on the interplay of three factors: (i) the angle θ between the “easy” z-axes of the dipolar spin–spin ( D SS ) and spin–orbit ( D SOC ) interaction tensors, (ii) the ratio of D SOC/D SS values, and (iii) the rhombicity parameters E SS/D SS and E SOC/D SOC. The study demonstrates in which cases organic quintet tetraradicals may have negative ZFS owing to the presence of heavy atoms at appropriate sites nearby the nitrene units and, thus, possess the bistability property as single-molecule magnets.
We present herein the synthesis, crystal structure, and electric and magnetic properties of the spin-crossover salt Mn(5-Cl-sal-N-1,5,8,12)TCNQ
⋅2 CH
CN (I), where ...5-Cl-sal-N-1,5,8,12=N,N'-bis(3-(2-oxy-5-chlorobenzylideneamino)propyl)-ethylenediamine, containing distinct conductive and magnetic blocks along with acetonitrile solvent molecules. The Mn
complex with a Schiff-base ligand, Mn(5-Cl-sal-N-1,5,8,12)
, acts as the magnetic unit, and the π-electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ
) is the conducting unit. The title compound (I) exhibits semiconducting behavior with room temperature conductivity σ
≈1×10
ohm
cm
and activation energy Δ ≈0.20 eV. In the temperature range 73-123 K, it experiences a hysteretic phase transition accompanied by a crossover between the low-spin S=1 and high-spin S=2 states of Mn
and changes in bond lengths within the MnN
O
octahedra. The pronounced shrinkage of the basal Mn-N bonds in I at the spin crossover suggests that the d
orbital is occupied/deoccupied in this transition. Interestingly, the bromo isomorphic counterpart Mn(5-Br-sal-N-1,5,8,12)TCNQ
⋅2 CH
CN (II) of the title compound evidences no spin-crossover phenomena and remains in the high-spin state in the temperature range 2-300 K. Comparison of the chloro and bromo compounds allows the thermal and spin-crossover contributions to the overall variation in bond lengths to be distinguished. The difference in magnetic behavior of these two salts has been ascribed to intermolecular supramolecular effects on the spin transition. Discrete hydrogen bonding exists between cations and cations and anions in both compounds. However, the hydrogen bonding in the crystals of II is much stronger than in I. The relatively close packing arrangement of the Mn(5-Br-sal-N-1,5,8,12)
cations probably precludes their spin transformation.
Complexes (dpp-BIAN)
Co
I
·MeCN (
) and (Py)
CoI
(
) were synthesized by the reaction between cobalt(II) iodide and 1,2-bis(2,6-diisopropylphenylimino)acenaphthene (dpp-BIAN) or pyridine (Py), ...respectively. The molecular structures of the complexes were determined by X-ray diffraction. The Co(II) ions in both compounds are in a distorted tetrahedral environment (CoN
I
). The electrochemical behavior of complex
was studied by cyclic voltammetry. Magnetochemical measurements revealed that when an external magnetic field is applied, both compounds exhibit the properties of field-induced single ion magnets.
Experimental and theoretical studies on aromatic nitrenes bearing from three to six unpaired electrons and having quartet, quintet, sextet or septet ground spin states, published in the last 15 years ...are analyzed. A comparative analysis of the magnetic properties of high-spin nitrenes and all other known high-spin organic molecules is performed. Promising areas of practical application of high-spin nitrenes as molecular magnets and as qubits and qudits for quantum computations are discussed. The bibliography includes 214 references.
The first X‐band EPR spectrum containing only non‐overlapping signals of septet pyridyl‐2,4,6‐trinitrene and triplet pyridylnitrenes is reported. This spectrum was recorded after photolysis of ...2,4,6‐triazidopyridine in solid argon at 5 K. The zero‐field splitting (ZFS) parameters of this trinitrene as well as of intermediate triplet mononitrenes and quintet dinitrenes formed at early stages of the photolysis were determined using the combination of modern computer line‐shape spectral simulations and density functional theory (DFT) calculations. It was found that septet pyridyl‐2,4,6‐trinitrene has the record negative parameter DS = −0.1031 cm−1 among all known to date septet pyridyl‐2,4,6‐trinitrenes and may be of interest as a model multi‐qubit spin system for investigations of quantum computation processing.
Septet pyridyl‐2,4,6‐trinitre with the record negative zero‐field splitting parameter D was generated by the photolysis of 2,4,6‐triazidopyridine in solid argon at 5 K and characterized with X‐band electron paramagnetic resonance (EPR) spectroscopy and modern computer line‐shape spectral simulations.
Three tetraphenylborates of mononuclear Mn(III) cation complexes with hexadentate ligands, the products of the reaction between a N,N′‐bis(3‐aminopropyl)ethylenediamine and salicylaldehydes with the ...different haloid substitutions at the 5 or 3,5 positions, have been synthesized: Mn(5‐F‐sal‐N‐1,5,8,12)BPh4 (1), Mn(3,5‐diCl‐sal‐N‐1,5,8,12)BPh4 (2) and Mn(3,5‐Br,Cl‐sal‐N‐1,5,8,12)BPh4 (3). Their crystal structure, dielectric constant (ϵ) and magnetic properties have been studied. Ligand substituents have a dramatic effect on the structure and magnetic properties of the complexes. With decreasing temperature, the complex (1) shows a gradual spin crossover from the high‐spin state (HS) to the HS:LS intermediate phase, followed by an abrupt transition to the low‐spin state (LS) without changing the crystal symmetry. The complexes 2 and 3 are isostructural, but have fundamentally different properties. Complex 2 demonstrates two structural phase transitions related to sharp spin crossovers from the HS to the HS:LS intermediate phase at 137 K and from the intermediate phase to the LS at 87 K, while complex 3 exhibits only one spin transition from the HS to the HS:LS intermediate phase at 83 K.
Effect of halide substituents on spin and phase transitions in Mn(III) complexes
The cationic complexes of Mn(III) with the 5-Hal-sal2323 (Hal = Cl, Br) ligands and a paramagnetic doubly charged counterion ReCl62− have been synthesized: Mn(5-Cl-sal2323)2ReCl6 (1) and ...Mn(5-Br-sal2323)2ReCl6 (2). Their crystal structures and magnetic properties have been studied. These isostructural two-component ionic compounds show a thermally induced spin transition at high temperature associated with the cationic subsystem and a field-induced slow magnetic relaxation of magnetization at cryogenic temperature, associated with the anionic subsystem. The compounds are the first examples of the coexistence of spin crossover and field-induced slow magnetic relaxation in the family of known MnIII(sal2323) cationic complexes with various counterions.
•Selective photolysis of nonequivalent azido groups in aromatic tetraazides.•Matrix isolation and EPR spectroscopic characterization of a new quintet dinitrene with s-triazine skeleton.•Effect of ...nonplanar structure on efficiency of the photolysis of azido groups in aromatic tetraazides.
The photolysis of 4,6-diazido-N-(4,6-diazido-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine in argon matrices at 5 K has been studied, using X-band EPR spectroscopy in combination with modern line-shape spectral simulations and density functional theory computations. It was found that the photolysis of the model tetraazide occurs selectively to give only triplet 4-azido-6-nitreno-N-(4,6-diazido-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine (D =1.45 cm−1, E =0.0045 cm−1) and quintet 4,6-dinitreno-N-(4,6-diazido-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine (D =0.276 cm−1, E =0.058 cm−1). The latter does not undergo further photolysis in the argon matrices since inappropriate spatial orientation of the second diazido-substituted triazine ring toward the UV source. The results obtained provide new data on photochemistry of aromatic tetraazides, formulating more strict requirements to the starting compounds as potential precursors of high-spin polynitrenes.
A coordination compound with the composition CoLCl
2
·H
2
O (
L
= bis-condensation product of diacetyl and 2-hydrazinyl-4,6-dimethylpyrimidine) was synthesized, in which the Co(
ii
) ion was ...hexacoordinated. Under applied DC fields, this compound exhibited single-ion magnet behavior. Two relaxation processes were observed when increasing the applied magnetic field from 1000 to 3200 Oe. The first relaxation (high-frequency) was observed both at 1000 Oe and 3200 Oe, while the second relaxation was only registered under a field of 3200 Oe at low frequencies (<1 Hz) and low temperatures (<5 K). Modeling of the magnetic DC properties using the Griffith Hamiltonian accompanied by quantum chemical calculations revealed easy-axis-type magnetic anisotropy with weak rhombic contributions.
This study presents the novel hexacoordinated Co(
ii
) mononuclear complex with SIM behavior.
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