A Layered Aluminophosphate [C17H21N2]3[Al3(PO4)4]·5H2O with Fluorescent Property Derived from Carbazolyl-Modified Template.

Designing and innovating organic structure-directing agents is the key to synthesizing novel molecular sieve structures. Herein, we design a novel carbazolyl-modified template and further synthesize a two-dimensional layered aluminophosphate with [C17H21N2]3[Al3(PO4)4]·5H2O (denoted as ZHKU-2). ZHKU-2 is composed of AA-stacked [Al3P4O16]3- layers constructed from alternating AlO4 and PO3(=O) tetrahedrons to form a 4.6.8 network featured by capped six-ring secondary building units. Carbazolyl-templated ZHKU-2 exhibits strong purple fluorescence with a high quantum yield of 25.98%. This work expands aluminophosphate materials of the [Al3P4O16]3- family and provides a view for synthesizing new molecular sieves by exploring the organic luminescence structure-directing agents.

A Mononuclear Iron(II) Spin-Crossover Molecule Decorated by Photochromic Azobenzene Group.

Aiming at constructing photoresponsive spin crossover (SCO) behavior, herein we designed a new ligand Abtz (Abtz = (E)-N-(4-((E)-phenyldiazenyl)phenyl)-1-(thiazol-4-yl)methanimine) which was decorated by a photochromic azobenzene group. Based on this photochromic ligand, a mononuclear Fe(II) SCO molecule [Fe(Abtz)3](BF4)2·(EAC)2 (1, EAC = ethyl acetate) was successfully synthesized and showed a complete one-step SCO behavior. Under continuous UV light and blue-light exposure, the cis-trans photoisomerization of both ligand Abtz and compound 1 in the liquid phase was confirmed through UV-Vis spectra. Moreover, the 1H-NMR spectra of Abtz reveal a trans-cis conversion ratio of 37%. Although the UV-Vis spectra reveal the photochromic behavior for 1 in the solution phase, the SCO behavior in the liquid state is absent according to the variable-temperature Evans method, suggesting the possible decomposition. Moreover, in the solid state, the cis-trans photoisomerization of both Abtz and 1 was not observed, due to the steric hindrance.

Spin-crossover modulation via single-crystal to single-crystal photochemical [2 + 2] reaction in Hofmann-type frameworks.

This study reports the first modulation of spin-crossover (SCO) behavior via a photochemical [2 + 2] cycloaddition reaction. Here we construct two no-solvent Fe(ii)-Ag(i) bimetallic Hofmann-type frameworks, [Fe(4-spy)2{Ag(CN)2}2] (1) and [Fe(2,4-bpe)2{Ag(CN)2}2] (2) (4-spy = 4-styrylpyridine, 2,4-bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene). For 1, the dimerization of 4-spy results in a single-crystal to single-crystal (SCSC) transformation from 2D interdigitated layers to a 3D interpenetrated structure. Additionally, a 3D → 3D structural transformation accompanied with Ag(i)-N bond breaking is achieved via the photochemical cycloaddition reaction of 2,4-bpe in 2. More importantly, both the spin transition temperatures and the SCO character are effectively modulated; thus, this approach provides a new strategy for constructing photo-responsive SCO magnetic materials.

SYSU-6, A New 2-D Aluminophosphate Zeolite Layer Precursor.

Two-dimensional aluminophosphate is an important precursor of phosphate-based zeolites; a new Sun Yat-sen University No. 6 (SYSU-6) with |Hada|2[Al2(HPO4)(PO4)2] has been synthesized in the hydrothermal synthesis with organic structure-directing agent (OSDA) of N,N,3,5-tetramethyladamantan-1-amine. In this paper, SYSU-6 is characterized by single-crystal/powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, infrared and UV Raman spectroscopy, solid-state 27Al, 31P and 13C magic angle spinning (MAS) NMR spectra, and elemental analysis. The single-crystal X-ray diffraction structure indicates that SYSU-6 crystallized in the space group P21/n, with a = 8.4119(3), b = 36.9876(12), c = 12.5674(3), α = 90°, ß = 108.6770(10)°, γ = 90°, V = 3704.3(2) Å3, Z = 4, R = 5.12%, for 8515 observed data (I > 2σ(I)). The structure has a new 4,12-ring layer framework topology linked by alternating AlO4 and PO4 tetrahedra. The organic molecules reside between the layers and are hydrogen-bonded to the inorganic framework. The new type of layer provides a greater opportunity to construct zeolite with novel topology.

Humidity Sensitive Structural Dynamics and Solvatomagnetic Effects in a 3D Co(II)-Based Coordination Polymer.

A chiral Co(II)-based coordination polymer, [Co3(pimda)2(H2O)5] (1, H3pimda = 2-propyl-1H-imidazole-4,5-dicarboxylic acid) with 3D hyperkagomé topology is reported. Upon heating/cooling, the water molecules which are coordinated to a pair of crystallographically symmetric Co(II) ions are removed/recovered discretely in two steps, giving [Co3(pimda)2(H2O)4] (2) and [Co3(pimda)2(H2O)3] (3), which is evidenced by the reversible single-crystal-to-single-crystal (SCSC) structural transformations. As the coordination geometry of the two Co(II) ions changes from octahedron to trigonal bipyramid, obvious color change from pink for 1 to dark violet for 2 and 3 is observed. Further magnetic measurements demonstrate the presence of a solvatomagnetic effect from paramagnets for 1 and 2 to weak ferromagnet for 3. Moreover, as revealed by the variable-temperature crystallographic measurements, the first and second dehydration temperatures could be controlled from 298 K (25 °C) and 383 K (110 °C) sealed in a capillary (high humidity) to 255 K (-18 °C) and 307 K (34 °C) in dry N2 (low humidity), indicating the strong humidity sensitivity of the structural dynamics.

Tunable Magnetization Dynamics through Solid-State Ligand Substitution Reaction.

The dimeric molecule [Dy2(acac)6(MeOH)2(bpe)]·bpe·2MeOH (1, acac = acetylacetonate, bpe = 1,2-bis(4-pyridyl)ethylene) undergoes a solid-state ligand substitution reaction upon heating, leading to the one-dimensional chain [Dy(acac)3(bpe)]n (2). This structural transformation takes advantage of the potential coordination of the guest bpe molecules present in 1. In both complexes the Dy(III) ions adopt similar octacoordinated D4d geometries. However, the different arrangement of the negatively charged and neutral ligands alters the direction of magnetic anisotropy axis and the energy states, thus resulting in largely distinct magnetization dynamics, as revealed by the CASSCF/RASSI calculations.

Magnetocaloric Properties of Heterometallic 3d-Gd Complexes Based on the [Gd(oda)3 ](3-) Metalloligand.

A series of heterometallic 3d-Gd(3+) complexes based on a lanthanide metalloligand, [M(H2 O)6 ][Gd(oda)3 ]⋅3 H2 O [M=Cr(3+) (1-Cr)] (H2 oda=2,2'-oxydiacetic acid), [M(H2 O)6 ][MGd(oda)3 ]2 ⋅3 H2 O [M=Mn(2+) (2-Mn), Fe(2+) (2-Fe) and Co(2+) (2-Co)], and [M3 Gd2 (oda)6 (H2 O)6 ]⋅12 H2 O [M=Ni(2+) (3-Ni), Cu(2+) (3-Cu), and Zn(2+) (3-Zn)], are reported. Magnetic and heat-capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of -ΔSm between complexes 2-Co and 1-Cr. In these two complexes, the 3d metal ions have the same spin (S=3/2 for Co(2+) and Cr(3+) ions), and the theoretical calculation suggested a larger -ΔSm value for 2-Co (47.8 J K(-1) kg(-1) ) than 1-Cr (37.5 J K(-1) kg(-1) ); however, the significant anisotropy of Co(2+) ions in 2-Co, which can result in smaller effective spins, gives a smaller value of -ΔSm for 2-Co (32.2 J K(-1) kg(-1) ) than for 1-Cr (35.4 J K(-1) kg(-1) ) at ΔH=9 T.

Modulation of single-molecule magnet behaviour via photochemical [2+2] cycloaddition.

The first example of phototunable SMMs has been reported. Upon UV irradiation, variations of the coordination sphere around Dy(III) ions actually affect the magnetic behaviour of the compound via [2+2] cycloaddition reaction, leading to a magnetic transformation from the SMM behaviour to a field-induced slow relaxation.