Invited for the cover of this issue is the group of Hua Mei and Yan Xu at Nanjing Tech University, China. The image depicts star-like {Tb26 } clusters, which are simplified as blue balls, and Ag atoms, which are distributed in the MOF structure uniformly to give a lanthanide-MOF structure with good optical properties. Read the full text of the article at 10.1002/chem.201405178.

Two original three-dimensional (3-D) 4d-4f heterometallic coordination polymers, [Ln(2)Ag(3)(IN)(5)(OH)(2) (NO3)][NO3]center dot nH(2)O (Ln = Eu, n = 2 (1); Ln = Ho, n = 1 (2); HIN = isonicotinic acid), have been synthesized by hydrothermal assemble of Ln(2)O(3) (Ln = Eu for 1; Ho for 2), HIN, AgNO3 and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, and thermogravimetric analysis (TGA). These two compounds show isostructural architectures and exhibit unusual 3-D open frameworks which are built upon the second ligand NO3- linking 2-D double wave-like [Ln(2)Ag(2)(IN)(4)(OH)(2)](n) layers and Ag(IN) subunits. 1-D channel is found in the framework. And the luminescent properties of the two compounds have also been investigated. (C) 2013 Elsevier B.V. All rights reserved.

Two new three-dimensional coordination compounds formulated as [Ln3(IN)2(bdc)3.5(H2O)3]·0.5H2O (Ln=Er 1, Ho 2), where HIN=isonicotinic acid and H2bdc=1,4-benzenedicarboxylic, have been obtained by hydrothermal assemble of Ln2O3 (Ln=Er 1, Ho 2), HIN and H2bdc. Structural analysis shows that Ln3+ ions are connected by both ligands IN− and bdc2− in 1 and 2. IN− links two adjacent {Ln3} units along b axis, while bdc2− connects eight {Ln3} units along different directions, which leads to an interesting strict {Ln3}8 quadrangular in 3D open frameworks of 1 and 2.

One new 3D La-Ag coordination compound formulated as [La2Ag3(IN)6(OAC)(H2O)3][NO3]2 center dot 2H2O (1) (HIN = isonicotinic acid; HOAC = acetic acid) was synthesized. The structure represents an interesting 3D open framework that is built upon 2D lanthanide layers and [Ag(IN)2]+ linkers. The triple helical [La(IN)2(H2O)]n chain and zigzag [LaIN(OAC)]n chain are found in the 2D La-IN layers. Channels are also found in the framework of 1, owing to shape-controlled synthesis templated by the free NO3 ions and water molecules.

Wireless sensor networks (WSNs) are widely being used in many environments (e.g., disaster relief and target tracking), and WSNs localization is still a crucial research area because of the new localization requirements for emerging application domains such as cyber-physical systems and cyber-transportation systems (CTS). In this article, we review different node localization approaches, and point out the issues and challenges of WSNs localization in emerging applications. First, the measurement-based techniques are introduced, and the range-free localization that is further classified into proximity-based localization, one-hop localization and multi-hop localization, is deeply analyzed. Then, the method of nonline-of-sight error mitigation is also reviewed. In addition, we give two representative applications (unmanned vehicle with WSNs navigation and CTS) to state the new obstacles for WSNs localization. Finally, the main issues and challenges for improving WSNs localization are outlined in brief.

Two new compounds, [Ho-26(IN)(28)(CH3COO)(4)(CO3)(10)(OH)(26)(H2O)(18)] center dot 20H(2)O (1) (HIN = isonicotinic acid) and [Er-26(IN)(29)(CH3COO)(3)(CO3)(10)(OH)(26)(H2O)(19)] center dot 26H(2)O (2), employing the building unit of CO3@Ln(26) have been synthesized hydrothermally. Compound 1 crystallizes in the triclinic space group P (1) over bar with a = 21.043(4) angstrom, b = 21.128(5) angstrom, c = 35.140(8) angstrom, alpha = 85.838(3)degrees, beta = 74.909(3)degrees, gamma = 85.414(3)degrees, V = 15,014(6) angstrom(3), Z = 2; 2 crystallizes in triclinic P (1) over tilde with a = 20.9968(15) angstrom, b = 21.1260(15) angstrom, c = 35.125(3) angstrom, alpha = 85.9530(10)degrees, beta = 74.7590(10)degrees, gamma = 85.5020(10)degrees, V = 14,966.3(18) angstrom(3) Z = 2. In the structures of both compounds, the isonicotinate (IN) is the main ligand while CH3COO- functions as the second ligand to stabilize the Ln(26) cluster; CO32- plays a very important role in the formation of the spherical Ln(26) cluster. The two compounds are isostructural and have been characterized by single-crystal X-ray diffraction, IR absorption spectroscopy, thermogravimetric analysis, ultraviolet excitation, and emission spectrum.

Hydrothermal reactions of lanthanide(III) oxide, isonicotinic acid, methanoic acid at 170 °C lead to two new lanthanide carbonate frameworks[Ln(IN)(CO3)(H2O)] (Ln La (1), Eu (2); HIN isonicotinic acid). Compounds 1 and 2 feature a two-dimensional (2D) architecture constructed by the intergrowth of infinite lanthanide carbonate layers. The enhanced fluorescence intensity of 2 indicates the effective energy transfer from the ligand to the Eu3+ center.

Two novel three-dimensional (3D) coordination polymers Zn1.5Dy26(IN)(25)(CH3COO)(8)(CO3)(11)(OH)(26)(H2O)(29) (1) and Zn1.5Gd26(IN)(26)(CH3COO)(7)(CO3)(11)(OH)(26)(H2O)(28) (2) based on the linkages of large nanosized spherical hydroxo Ln(26) clusters and zinc centers by organic ligands have been hydrothermally synthesized. Metal organic framework (MOF) 1 crystallizes in the triclinic space group P (1) over bar, with a = 21.107(2) angstrom, b = 21.185(2) angstrom, c = 36.323(4) angstrom, alpha = 89.001(2)degrees, beta = 82.486(2)degrees, gamma = 68.359(2)degrees, V = 14960(3) angstrom(3), Z = 2. MOF 2 crystallizes in the triclinic space group P (1) over bar, a = 19.6213(15) angstrom, b = 22.1850(17) angstrom, c = 34.654(3) angstrom, alpha = 88.5340(210)degrees, beta = 85.6520(10)degrees, gamma = 72.9790(19)degrees V = 14382.5(19) angstrom(3), Z = 2. Structural analysis indicates that both 3D polymers can be constructed using the building unit of CO3@Ln(26) (Dy for 1, Gd for 2) and exhibit similar topological frameworks. During the synthesis, three ligands were used. CO32- plays a very important role in the formation of the spherical Ln(26) cluster. CH3COO- makes the Ln(26) cluster stable and reduces steric restriction. The isonicotinate (1N) stabilizes the cluster and links the clusters and the Zn centers.