Xiaoquan Zhu

From Pair Quadruple- to Single-Stranded Helices to Lines in a Mixed Ligand System via Adjusting the N-Substituent of l-Glu

Utilizing the mixed-ligand strategy, a novel fourfold-interpenetrated 3D homochiral metal-organic framework (1) with rare pair quadruple-stranded helices was assembled from bpee (1,2-bis(4-pyridyl)ethylene) and NCG (N-carbamyl-l-glutamate). Changing the carbamyl substituent of NCG with benzoyl group (NBzG: N-benzoyl-l-glutamate), a non-interpenetrated 3D homochiral coordination polymer (2) composed of alternate right-handed and left-handed single helix was obtained. When p-tolylsulfonyl substituent was used instead, an interesting homochiral linear structure (3) was formed from mixed-ligand bpee and NTsG (N-p-tolylsulfonyl-l-glutamate), with all individual NTsG being lined up orderly. The steric hindrance of N-substituent of l-glu has a tremendous impact on the construction of these diverse frameworks. Complexes 1-3 display second harmonic generation (SHG) efficiencies, which are approximately 0.32, 0.45, and 0.55 times as much as that of KDP powder.

1D to 3D and Chiral to Noncentrosymmetric Metal–Organic Complexes Controlled by the Amount of DEF Solvent: Photoluminescent and NLO Properties

A mixture of 2D and 1D metal-organic complexes, [ZnL(H2O)2·G1·DEF·2H2O]n (1a: G1 = naphthalene-2,7-disulfonate; DEF = N,N-diethylformamide) and [ZnL(H2O)3·G1·DEF·2H2O]n (2), has been prepared from a hydrogenated Schiff base L and Zn(II) in a DEF-contained solvent system under mild conditions. The yields of 1a and 2 are equivalent; however, they can be tuned by varying the amount of DEF solvent. Increasing the use of DEF tends to form pure 1a, while decreasing it generates 2. Without DEF, another novel 3D four-connected CdSO4 (cds) framework [ZnL(H2O)2·G1·2H2O]n (3) composed of alternated right-handed and left-handed helical chains has been constructed. The amount of DEF solvent has a significant impact on the diverse coordination architectures of 1-3, which is rare in the preparation of metal-organic complexes. The photoluminescence of complexes 1-3 along with naphthalene-2,7-disulfonate has been investigated in the solid state. The luminescent emission of G1 was enhanced greatly after being confined into metal-organic networks. In addition, complexes 1-3 display second-harmonic generation efficiencies, which are approximately 0.58, 0.42, 0.32, and 0.52 times as much as that of potassium dihydrogen phosphate.

Synthesis, structure, characterization, and multifunctional properties of a family of rare earth organic frameworks

A series of isomorphic 3D layered rare earth hydroxide (LREH) frameworks RE3(OH)7(1,5-NDS) (RE = Y (1), Gd (2), Er (3), Yb (4); 1,5-NDS = 1,5-naphthalenedisulfonate) has been synthesized under hydrothermal conditions. The crystal structures, thermal stabilities, photoluminescence, and magnetic properties of these compounds have been investigated. The results demonstrate that the compounds are highly stable even at 351 °C and emit strong purple fluorescence, whose colour can be tuned by the coordinated rare earth ions. Their magnetic susceptibilities have also been measured, leading the compounds to be promising multifunctional materials.

Intercalation of Varied Sulfonates into a Layered MOC: Confinement-Caused Tunable Luminescence and Novel Properties†

The pores/channels of porous 3D metal-organic frameworks (MOFs) have been widely applied to incorporate gas, solvent, or organic molecules. On the contrary, the utilization of the interlamellar void of layered metal-organic complexes (MOCs) remains underappreciated, although it is more flexible and available to accommodate molecules with different sizes. In this work, diverse sulfonates have been intercalated purposely into an identical layered MOC, which constructed various novel intercalation compounds possessing fluorescent, white-light emitting, photochromic, homochiral, or nonlinear optical (NLO) properties. With the help of single-crystal X-ray diffraction, their structures and the mutual interactions between the MOC host and the sulfonate guests were characterized. The properties of the guest molecules were tuned and meanwhile some new performances were generated after confining them into the interlayer region. Such a hybrid approach provides an efficient strategy to design and prepare multifunctional materials.

Syntheses, structures, luminescence and magnetic properties of seven isomorphous metal–organic frameworks based on 2,7-bis(4-benzoic acid)-N-(4-benzoic acid)carbazole

We report herein seven novel lanthanide metal–organic frameworks (Ln-MOFs), [M(L27)(DMA)(H2O)·XH2O]n (TCZ-M), (M = Nd, Sm, Eu, Gd, Tb, Dy, Ho), (X = 2 or 3) (H3L27 = 2,7-bis(4-benzoic acid)-N-(4-benzoic acid)carbazole, DMA = N,N-dimethylacetamide, TCZ = “T”-shape carbazole-based MOFs, L27 = fully deprotonated H3L273− ligand). X-ray crystallography showed that all the TCZ-M (M = Nd, Sm, Eu, Gd, Tb, Dy, Ho) are isomorphous and possess a 3,6-connected three-dimensional (3D) framework with a point symbol of {4·62}2{42·610·83}. The photoluminescence measurement indicates that TCZ-Eu shows reddish-orange emission bands and TCZ-Sm shows both visible and near-infrared (NIR) emission bands. Magnetic susceptibility measurements show deviations from the Curie law mainly owing to the split of the ground term due to the ligand field and spin–orbit coupling in TCZ-Eu and TCZ-Sm. The magnetic properties of TCZ-M (M = Nd, Gd, Tb, Dy, Ho) are also investigated, and the results indicate a ferromagnetic interaction between the Tb3+ magnetic centers in TCZ-Tb and the antiferromagnetic interactions in TCZ-M (M = Nd, Gd, Dy, Ho).

Syntheses, crystal structures, and magnetic properties of cyanide-bridged complexes trans-RuII(dppe)2(CN)2(FeIIIX3)2 (X = Cl and Br)

The syntheses, crystal structures and electronic absorption spectra of cyanide-bridged complexes trans-RuII(dppe)2(CN)2(FeIIIX3)2 (X = Cl, 2; X = Br, 3; dppe = 1,2-bis(diphenylphosphino)ethane) and their parent trans-RuII(dppe)2(CN)2 (1) were reported. Both the crystal structural data and MMCT (metal-to-metal charge transfer) indicate the existence of some electron delocalization along the FeIII–NC–RuII arrays in complexes 2 and 3. The magnetic properties of complexes 2 and 3 reveal dominant antiferromagnetic coupling, and complex 3 exhibits spin-canted behavior below 6.5 K.

CCDC 1513622: Experimental Crystal Structure Determination

Related Article: Xiaoquan Zhu, Shaodong Su, Wenhai Cao, Shengmin Hu, Yuehong Wen, Xintao Wu, Tianlu Sheng|2017|Dalton Trans.|46|1038|doi:10.1039/C6DT04397F

CCDC 1527834: Experimental Crystal Structure Determination

Related Article: Haoran Li, Tianlu Sheng, Zhenzhen Xue, Xiaoquan Zhu, Shengmin Hu, Yuehong Wen, Ruibiao Fu, Chao Zhuo, Xintao Wu|2017|CrystEngComm|19|2106|doi:10.1039/C7CE00202E