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An organic material single crystal of [BzIQl][PIC] ([BzIQl]+ = benzylisoquinolinium; [PIC]− = picrate) has been grown by slow evaporation solution growth technique. Single crystal XRD studies reveal the crystal belongs to monoclinic system with C2/c. The two neighboring [PIC]− anions form a dimer through π⋯π interaction, while the cations stack to a columnar structure through C-H⋯π and π⋯π interactions. The anions (A) and cations (C) are arranged into a columnar structure in a ⋯AA-CC-AA-CC⋯sequence through C-H⋯O hydrogen bonds. The cations and anions are linked through electrostatic and other hydrogen bonding interactions form 3D network. The power XRD measurements substantiate the quality of the crystal. The presence of functional groups of the organic material was confirmed by FT-IR and FT-Raman analysis and theoretical studies. Differential thermal analysis (DTA) carried out on the grown crystal indicates that the material is stable up to 224.9 °C. Additionally, the organic material shows three main emission peaks about 385, 467 and 538 nm upon excitation at 241 nm in solid state at room temperature.

Two half-sandwich organodysprosium complexes [(C7H8)Dy(AlCl4)3] and [(C7H8)Dy(AlBr4)3] were synthesized by modifying the arene ligand of the complex [(C6Me6)Dy(AlCl4)3]. Single X-ray diffraction data reveals the local geometry of Dy(III) ion is close to pentagonal bipyramid. Magnetic investigation shows both are single-ion magnets with enhanced magnetic properties.

The single-molecule magnetism of sandwich tetrapyrrole lanthanide compounds has clearly initiated a huge renaissance in the magnetochemistry of pure lanthanide coordination complexes. In this review, we focus on their structure–function relationships, their historical evolution, and preliminary efforts in surface effect on the SMM properties of multikis(tetrapyrrole) lanthanide complexes for the development of spintronic devices.

Presented here are the structures and magnetism of two isostructural magnetic Cl-bridged chain compounds of the type (H2mela)2[MCl5]Cl (mela melamine, M Fe(II) (1), M Mn(II) (2)). The chain structure is formed along the Jahn–Teller elongation axis of the MCl6 octahedra. In compound 1, the Cl− ion transmits an antiferromagnetic exchange interaction that, combined with the magnetic anisotropy of the Fe(II) sites, gives rise to a canted antiferromagnetic arrangement of the spins. Detailed magnetic studies revealed that 1 exhibits slow magnetic relaxation behavior like single-chain magnet (SCM), and that the finite size effects, due to naturally occurring defects, strongly influences the static and dynamic properties of 1. The contribution of the correlation length to the energy barrier has also been investigated. The Mn compound 2 is an isotropic Heisenberg chain with antiferromagnetic coupling between the Mn(II) ions. Doped crystals of Zn1, Cu1–Cu5 and Mn1–Mn5 were synthesized by introducing different contents of Zn(II), Cu(II) and Mn(II) ions to study the magnetic dilution and decoupling phenomena, respectively.

An asymmetric bridging ligand 3,4′-bi-1,2,4-triazole (Hbtr) was used for constructing transition metal coordination polymer, and yielding a manganese(II) compound [Mn(btr)2]n (1) with a unique three-dimensional (3D) framework. Single-crystal X-ray diffraction reveals that 1 crystallizes in the orthorhombic space group Fdd2 and the structure is 3D (3, 6)-connected topological framework constructed from manganese ions and μ3-btr ligands. The magnetic investigation for compound 1 shows that it is an antiferromagnetically coupled 3D array of high-spin manganese(II) ions with long-range ordering below T = 2.6 K, which is a weak ferromagnetic state due to spin-canting.

The reactions of Mn(ClO4)2·6H2O, 1-(2-hydroxyphenyl)ethanone oxime (abbr. as MeSao), NEt3 and thiophene-2-carboxylic acid/thiophene-3-carboxylic acid (2-TCA/3-TCA) lead to [Mn6O2(MeSao)6(2-TCA)2(EtOH)4(H2O)2](EtOH)2 (1) and [Mn6O2(MeSao)6(3-TCA)2(EtOH)4(H2O)2](EtOH)2 (2), respectively. Their structures can be described as a core of the [MnIII6O2(Mesao)6(O2C-thiophene)2(EtOH)4] consisting two off-set, stacked [MnIII3(μ3-O2−)]7+ triangular subunits linked by two central oximato O-atoms and two O-atoms from phenoxide group. Magnetic investigation revealed that 1 and 2 all have a spin ground state S = 4, and both complexes show single-molecule magnet behaviors with similar energy barriers Ueff ∼45 K.

Four azide and oxo bridged polynuclear Ni(II) and Co(II) complexes have been constructed by the simultaneous use of Hhdeo (Hhdeo = 2-hydroxy-[1,2-di(pyridin-2-yl)] ethane-1-one) and azide as ligands: [Ni6(Hhdeo)2(hdeo)4(N3)6] · (ClO4)2 · 2DMF · 2H2O (1), [Co6(Hhdeo)2(hdeo)4(N3)6] · (ClO4)2 · 2DMF · 2H2O (2), [Ni6(Hhdeo)2(hdeo)4(N3)6] · (ClO4)2 · 6H2O (3) and [Co7(hdeo)6(N3)6] · (ClO4)2 · 2H2O (4). Compounds 1–3 all crystallize in monoclinic space group P21/c, and consist of face-shared tetracubane hexanuclear cores, which are bridged by μ2, μ3-O and μ2-1,1, μ3-1,1,1-N3. Compound 4 crystallizes in triclinic space group P 1 ¯ , and is made up of wheel-like heptanuclear cores [Co7(hdeo)6(N3)6]2+ bridged by μ2-O and μ3-1,1,1-N3. For Co(II), the reaction solvents are found to play important roles in directing the final products with hexanuclear or heptanuclear topologies. Magnetic studies demonstrate overall intra-molecular ferromagnetic (F) couplings in these four compounds, which result from, according to our theoretical analysis, the competition between different kinds of exchange interactions within the metallic triangle units. No single-molecule magnet behavior was observed above 1.9 K in complex 1–3. However, compound 4 shows significant slow relaxation at static zero and 600 Oe fields below 4 K, towards single molecule magnet (SMM) behavior.

A new practical approach to molecular magnetism was suggested. First, for the complicated magnetic exchange system with unquenched orbital angular momentum a general form of the effective Hamiltonian including an intercluster exchange interaction of the self-consistent field was introduced. On the basis of the irreducible tensor operator method the practical approach was established, and accomplished by the BJMAG package, where a new strategy to automatically search more good quantum numbers was adopted to solve further block diagonalization in the eigenvalue problem. Finally, potentiality of the approach to isotropic Heisenberg spin clusters was tested through two high-nuclearity clusters, the nonamer cluster and the Mn 7 -cluster compound as representative examples.

For the title complexes the ab initio calculations of the ground and low-lying exited states have been carried out at level of MRCI(SD)+Q method. Through mapping to the spin model space the magnetic coupling constant (2.33 cm−1) between the Mn(II) ions was obtained, comparing with experimental value of 0.49 cm−1, and it is found that the Lande rule of the magnetic behavior is valid for the magnetic system. The DFT–BS calculations were used to examine the magneto-structural correlation. It is shown that as increase of the bridge-bonding angle the transition from ferromagnetic to antiferromagnetic coupling may occur, consistent with experimentally observations.

An intermediate in photoinduced magnetization process for the photomagnetic high-spin molecule [MoIV(CN)2(CN-CuL)6]8+ is studied with quantum chemistry calculations of the density functional theory and the ab initio multireference configuration interaction methods. It is found that the intramolecular electronic transfer from MoIV to CuII leads one trigonal-bipyamid coordinated CuII to be changed to the tetrahedral coordinated CuI with the light irradiation. The calculated magnetic properties show that the paramagnetic system [MoIV(CN)2(CN-CuIIL)6]8+ with six isolated spin 1/2 Cu ions is changed to ferromagnetic coupling high-spin system [MoV(CN)2(CN-CuIIL)5(CN-CuIL)]8+. These calculations will help to understand photoinduced magnetization phenomenon and provide a clue for the synthesization of new reversible photoinduced magnetic compounds.

Ab initio calculations on the ground and low-lying electronic states of the BrCl molecule have been carried out within the framework of the internally contracted multireference singles and doubles configuration interaction method by using the all-electronic basis sets cc-pVTZ-DK with Davidson size-extensively correction and Douglas-Kroll-Hess scalar relativistic correction. The spin-orbit coupling interactions are further taken into account through the state interaction approach with the full Breit-Pauli operator. The 23 Ω states generated from the 12 Λ − S states are studied. The spectroscopic constants of the bound states are derived by fitting the calculated potential energy curves. The calculated potential barrier of B 3 Π 0 + is located at the internuclear distance R of 3.261 A and lies on 236.8 cm−1 above the first dissociation limit, consistent with experimentally the potential barrier height (275 cm−1) and the intersection location R (3.26 A). The spin-orbit coupling between the B 3 Π 0 + state and the essentially unbound state Y0+ is investigated. It is shown that the B 3 Π 0 + state is significantly mixed with another 3 Π 0 + state as well as 3 Σ 0 + - state, and the former is dominant. On the basis of the selection rule of the spin-orbit coupling and analysis of the Ω state components, the intersection of the repulsive C 1Π1 state with the attractive branch of the B 3 Π 0 + potential curve near the level of the first molecular dissociation limit is confirmed to be forbidden for the spin-orbit coupling, and theoretically it is further suggested that the possible rotation-electronic coupling between B 3 Π 0 + and C 1Π1 is responsible for the spontaneous predissociation of the B 3 Π 0 + state. The basis set superposition errors for the calculated spectroscopic constants are examined. Also the effects of the basis set and the theoretical methods on the calculated dissociation energy of the ground state are briefly discussed.

Ab initio calculations on the potential energy curves and electronic structures of the ground and low-lying electronic states for the mixed transition metal dimer CrCu have been carried out by using the internally contracted multireference singles and doubles configuration interaction method MRCI(SD) + Q. The spectroscopic constants of the selected electronic states were obtained. The results are presented supporting the 6Σ+ ground state, by contrast to the assigned ground state 4Σ in ESR of CrCu. The electronic structures of the ground state and the low-lying states are multireference in character, and the ground state 6Σ+ is mainly dominated by strong intra-atomic d–d exchange interactions on the atom Cr.

The theoretical calculations on magnetic exchange of the title complex are carried out by using multiconfigurational second-order perturbation theory, CASPT2, and density functional theory combined with broken-symmetry approach, DFT-BS. The CASPT2 calculated quartet ground state, stabilized by 8.02 cm −1 compared with the nearest excited doublet state, is close to 5 cm −1 of the experimental measurement. The dependence of energy levels on the ratio J 23 / J 12,13 validates occurrence of the spin frustration phenomenon. Both CASPT2 and DFT-BS calculations reproduce well experimentally coupling constants of J 12,13 = −9.35 cm −1 , J 23 = −3.95 cm −1 , for CASPT2 J 12,13 = −6 cm −1 , J 23 = −2 cm −1 and for DFT-BS J 12,13 = −11.31 cm −1 , J 23 = −4.20 m −1 . The methodological comparison is briefly discussed.