Explore the vast range of titles available.

Single-molecule magnet (SMM) properties of crystals of a terbium(III)-phthalocyaninato double-decker complex with different molecular packings (1: TbPc2, 2: TbPc2·CH2Cl2) were studied to elucidate the relationship between the molecular packing and SMM properties. From single crystal X-ray analyses, the high symmetry of the coordination environment of 2 suggested that the SMM properties were improved. Furthermore, the shorter intermolecular Tb–Tb distance and relative collinear alignment of the magnetic dipole in 2 indicated that the magnetic dipole–dipole interactions were stronger than those in 1. This was confirmed by using direct current magnetic measurements. From alternating current magnetic measurements, the activation energy for spin reversal for 1 and 2 were similar. However, the relaxation time for 2 is three orders of magnitude slower than that for 1 in the low-T region due to effective suppression of the quantum tunneling of the magnetization. These results suggest that the SMM properties of TbPc2 highly depend on the molecular packing.

Phthalocyanines and their double-decker complexes are interesting in designing rotative molecular machines, which are crucial for the development of molecular motors and gears. This study explores the design and synthesis of three bulky phthalocyanine ligands functionalized at the α-positions with phenothiazine or carbazole fragments, aiming to investigate dynamic rotational motions in these sterically hindered molecular complexes. Homoleptic and heteroleptic double-decker complexes were synthesized through the complexation of these ligands with Ce(IV). Notably, CeIV(Pc2)2 and CeIV(Pc3)2, both homoleptic complexes, exhibited blocked rotational motions even at high temperatures. The heteroleptic CeIV(Pc)(Pc3) complex, designed to lower symmetry, demonstrated switchable rotation along the pseudo-C4 symmetry axis upon heating the solution. Variable-temperature 1H-NMR studies revealed distinct dynamic behaviors in these complexes. This study provides insights into the rotational dynamics of sterically hindered double-decker complexes, paving the way for their use in the field of rotative molecular machines.

This article studies the supramolecular assembly behavior of a Zn-trisporphyrin conjugate containing a triphenylamine core (1) with bridging N-donor ligands using the UV-vis spectrophotometric titration method at micromolar concentrations. Our results show that pyridine, a non-bridging ligand, formed a 3:1 open complex with 1. The corresponding binding constant was estimated to be (2.7 ± 0.15) × 1014 M−3. In contrast, bridging ligands, 4,4-bipyridine (BIPY) and 1,3-di(4-pyridyl)propane (DPYP), formed stable 3:2 double-decker complexes with 1 in solution, which collapsed to yield a 3:1 open complex when excess BIPY or DPYP was added. The binding constants for forming BIPY and DPYP double-decker complexes were estimated to be (9.26 ± 0.07) × 1027 M−4 and (3.62 ± 0.16) × 1027 M−4, respectively. The UV-vis titration profiles supported the conclusion that the degradation of the 3:2 double-decker 1∙BIPY complex is less favorable compared to that of 1∙DPYP. Consequently, the formation of the 3:1 1∙DPYP open complex proceeded more readily than that of 1∙BIPY.

A novel double-decker porphyrin complex, bismeso-tetrakis(4-N-alkylpyridiniumyl)porphyrinatocerium, was prepared. Electrochemical measurements revealed that this complex exhibited reversible redox waves corresponding to a 1e– redox reaction of the cerium center. Treating the complex alternately with an oxidant and a reductant resulted in the reversible redox switching between the oxidized and reduced states in an organic solvent.

Phosphorescent Pt(II) complexes have garnered significant attention as key components in luminescence-based systems due to their highly efficient emission properties. A notable characteristic of these complexes is their ability to form excimers through strong molecular stacking in concentrated solutions or solid film states. This aggregation-driven emission, primarily arising from metal–metal to ligand charge transfer (MMLCT), is influenced by overlapping d-orbitals oriented perpendicular to the square planar structure of the Pt(II) complexes. Although this property hinders the development of pure blue-emitting Pt(II) complexes, it facilitates the design of materials that emit red- and near-infrared (NIR) light. By employing advanced molecular design techniques, dinuclear Pt(II) complexes have been optimized to significantly enhance red and NIR emissions through the modulation of Pt-Pt interactions and adjustments in ligand electron densities. This review elucidates how the control of Pt-Pt distances and strategic ligand modifications can directly influence the emission spectra toward red and NIR regions. A comparative analysis of recent studies underscores the novelty and effectiveness of double-decker-type dinuclear Pt(II) complexes in achieving efficient emission characteristics in the long-wavelength range. These insights may guide the design of molecular structures for next-generation organometallic phosphorescent materials.

A novel double-decker porphyrin complex, bis{ -tetrakis(4- -alkylpyridiniumyl)porphyrinato}cerium, was prepared. Electrochemical measurements revealed that this complex exhibited reversible redox waves corresponding to a 1e redox reaction of the cerium center. Treating the complex alternately with an oxidant and a reductant resulted in the reversible redox switching between the oxidized and reduced states in an organic solvent.

Mixed-ligand double-decker lutetium, erbium, dysprosium, gadolinium, and europium complexes with tetra- tert -butyltetrabenzoporphyrin and phthalocyanine have been synthesized, and their structure was confirmed by IR, 1 H NMR, and mass spectra. Relations have been found between the electronic absorption and luminescence spectra of the complexes and radius of the central metal ion.

Novel neodymium phthalocyaninates based on template condensation of 4-[(4-benzyloxy)phenoxy]- or 4-(1-methyl-1-phenylethyl)phenoxyphthalonitriles with neodymium salts were obtained. The most selective preparation of neodymium sandwich complexes was found to occur with neodymium acetate as a template. The spectroscopic properties of neodymium metal complexes synthesized in organic solvents were studied. It was determined sandwich complexes of neodymium forms a mixture of in \"blue\" and \"green\" forms in the solution.

The SMM properties of the spatially closed Dy(III) double-decker Pc complex Dy(obPc) 2 ( 1 ), which is equivalent to a pseudo dinuclear complex, are reported. Complex 1 crystallized with ethanol in the crystal lattice in the monoclinic space group P 2 1 / n and was isomorphous with Tb(obPc) 2 ( 3 ), which is arranged in a dimer structure along the b axis. The intermetallic Dy-Dy distance was determined to be 0.756 nm. χ M T versus T plots for 1 decreased with a decrease in T , which suggests the existence of an antiferromagnetic (AF) interaction between the Dy 3+ ions. The M-H curve for 1 at 1.8 K showed magnetic hysteresis. In ac susceptibility measurements on a powder sample of 1 , which were dependent on the applied ac field, indicating that 1 is an single molecule magnet (SMM), a maximum appeared at 22 K at an ac frequency ( f ) of 1488 Hz. The shape of the peaks drastically changed, and the peaks did not shift when an H dc large enough to suppress the quantum tunneling of the magnetization (QTM) was applied. The energy barrier ( Δ/hc ) was estimated to be 44 cm −1 with a pre-exponential factor ( τ 0 ) of 1.6 × 10 −5 s from an Arrhenius plot. Our results suggest that the SMM/magnetic properties of 1 significantly change in a dc magnetic field. These relaxation mechanisms are related to the energy gap of the ground state and to QTM.

New rotary molecular machines ( 1 and 2 ) were synthetically constructed from two distinct porphyrin-based rotors, a cerium(IV) bis(porphyrinate)s double-decker (CeDD) and a porphyrinatorhodium(III)-based rotor. These rotors are adjacently mounted on rotational axes aligned to near vertical as resembling the bevel-gear-shaped structure. Structural study using NMR analysis reveals that these distinct rotors are connected through a coordination bond between rhodium(III) and a pyridyl group. At temperature from 193 to 393 K, each rotor represents rotational motion driven by heat fluctuation without decomposition into the corresponding precursors in dichloromethane- d 2 and tetrachloroethane- d 4 . Importantly, the mechanical interaction between the teeth of these rotors is strongly dependent on the central metal atom in a DD rotor and the teeth structure in a porphyrinatorhodium(III)-based rotor. Understanding such relationship between the chemical structures and mechanical interaction is of importance for generating cooperative motion in the hybrid machinery system.