Photoinduced Rapid and Explosive Fragmentation of Diarylethene Crystals Having Urethane Bonding

Photoinduced Rapid and Explosive Fragmentation of Diarylethene Crystals Having Urethane Bondin

Photoinduced Rapid and Explosive Fragmentation of Diarylethene Crystals Having Urethane Bonding

Photoinduced Rapid and Explosive Fragmentation of Diarylethene Crystals Having Urethane Bondin

Mechanical Behavior of Molecular Crystals Induced by Combination of Photochromic Reaction and Reversible Single-Crystal-to-Single-Crystal Phase Transition

We herein report a unique mechanical behavior of a molecular crystal induced by combination of a photochromic reaction and a reversible single-crystal-to-single-crystal (SCSC) phase transition. A crystal of a diarylethene having octyl group at both sides (<b>1a</b>) was found to undergo a reversible thermodynamic SCSC phase transition accompanying a change in crystal length, which was clarified by differential scanning calorimetry measurement, X-ray crystallographic analysis, and direct microscopic observation of the crystal length. Furthermore, upon irradiation with ultraviolet light, the diarylethene crystal exhibited an unusual photomechanical behavior. The mechanism of the behavior was proposed based on photoisomerization of the diarylethene from the open-ring isomer to the closed-ring isomer and a reversible thermodynamic SCSC phase transition, which was well-supported by thermal bending behavior of a photoirradiated crystal

Selective Deprotection Method of <i>N</i>‑Phenylcarbamoyl Group

We report an improved method for the selective deprotection of the <i>N</i>-phenylcarbamoyl group, which yields the corresponding alcohol without affecting other protecting groups. Deprotection was performed using di-<i>tert</i>-butyl dicarbonate and tetra-<i>n</i>-butylammonium nitrite (Boc₂O and Bu₄NNO₂) in pyridine at room temperature. This method is also effective for deprotecting the fluorous <i>N</i>-phenylcarbamoyl group

Excited State Engineering in Ag₂₉ Nanocluster through Peripheral Modification with Silver(I) Complexes for Bright Near-Infrared Photoluminescence

The optical property of an ionic metal nanocluster (NC) is affected by the ionic interaction with counter ions. Here, we report that the modification of trianionic [Ag29(BDT)12(TPP)4]3– NC (BDT: 1.3-benzenedithiol; TPP: triphenylphosphine) with silver(I) complexes led to the intense photoluminescence (PL) in the near-infrared (NIR) region. The binding of silver(I) complexes to the peripheral region of Ag29 NC is confirmed by the single-crystal X-ray diffraction (SCXRD) measurement, which is further supported by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The change of excited-state dynamics by the binding of silver(I) complexes is discussed based on the results of a transient absorption study as well as temperature-dependent PL spectra and PL lifetime measurements. The modification of Ag29 NCs with cationic silver(I) complexes is considered to give rise to a triplet excited state responsible for the intense NIR PL. These findings also afford important insights into the origin of the PL mechanism as well as the possible light-driven motion in Ag29-based NCs

Anion-Controlled Assembly of Four Manganese Ions: Structural, Magnetic, and Electrochemical Properties of Tetramanganese Complexes Stabilized by Xanthene-Bridged Schiff Base Ligands

The reaction of manganese­(II) acetate with a xanthene-bridged bis­[3-(salicylideneamino)-1-propanol] ligand, H₄L, afforded the tetramanganese­(II,II,III,III) complex [Mn₄(L)₂(μ-OAc)₂], which has an incomplete double-cubane structure. The corresponding reaction using manganese­(II) chloride in the presence of a base gave the tetramanganese­(III,III,III,III) complex [Mn₄(L)₂Cl₃(μ₄-Cl)­(OH₂)], in which four Mn ions are bridged by a Cl^– ion. A pair of L ligands has a propensity to incorporate four Mn ions, the arrangement and oxidation states of which are dependent on the coexistent anions

Anion-Controlled Assembly of Four Manganese Ions: Structural, Magnetic, and Electrochemical Properties of Tetramanganese Complexes Stabilized by Xanthene-Bridged Schiff Base Ligands

The reaction of manganese­(II) acetate with a xanthene-bridged bis­[3-(salicylideneamino)-1-propanol] ligand, H₄L, afforded the tetramanganese­(II,II,III,III) complex [Mn₄(L)₂(μ-OAc)₂], which has an incomplete double-cubane structure. The corresponding reaction using manganese­(II) chloride in the presence of a base gave the tetramanganese­(III,III,III,III) complex [Mn₄(L)₂Cl₃(μ₄-Cl)­(OH₂)], in which four Mn ions are bridged by a Cl^– ion. A pair of L ligands has a propensity to incorporate four Mn ions, the arrangement and oxidation states of which are dependent on the coexistent anions

An Enantiopair of Organic Ferromagnet Crystals Based on Helical Molecular Packing of Achiral Organic Radicals

We report the ferromagnetic ordering phenomena occurring in organic molecular crystals with structural chirality. Achiral radical <b>1</b> has been found to crystallize in two enantiomorphs with chiral space groups of <i>P</i>4₃ and <i>P</i>4₁. The <i>P</i>4₃ form (<b>1L</b>) has left-handed stacking of the molecules, giving the helical chirality in a crystalline solid. In the other form of <i>P</i>4₁ (<b>1R</b>), the right-handed stacking corresponds to a mirror image of <b>1L</b>. Magnetic susceptibility measurements show that both the crystals undergo a ferromagnetic phase transition at <i>T</i>_C = 1.1 K. The ferromagnetic ordering has been confirmed by heat capacity measurements. The magnetic heat capacity exhibits a λ-shaped peak at <i>T</i>_C = 1.1 K with an entropy change of <i>R </i>ln 2, as expected for <i>S</i> = 1/2 spins. This is the first example of genuinely organic molecule-based ferromagnetism associated with the structural chirality based on the helical molecular packing in the crystalline solid

An Enantiopair of Organic Ferromagnet Crystals Based on Helical Molecular Packing of Achiral Organic Radicals

We report the ferromagnetic ordering phenomena occurring in organic molecular crystals with structural chirality. Achiral radical <b>1</b> has been found to crystallize in two enantiomorphs with chiral space groups of <i>P</i>4₃ and <i>P</i>4₁. The <i>P</i>4₃ form (<b>1L</b>) has left-handed stacking of the molecules, giving the helical chirality in a crystalline solid. In the other form of <i>P</i>4₁ (<b>1R</b>), the right-handed stacking corresponds to a mirror image of <b>1L</b>. Magnetic susceptibility measurements show that both the crystals undergo a ferromagnetic phase transition at <i>T</i>_C = 1.1 K. The ferromagnetic ordering has been confirmed by heat capacity measurements. The magnetic heat capacity exhibits a λ-shaped peak at <i>T</i>_C = 1.1 K with an entropy change of <i>R </i>ln 2, as expected for <i>S</i> = 1/2 spins. This is the first example of genuinely organic molecule-based ferromagnetism associated with the structural chirality based on the helical molecular packing in the crystalline solid