A novel double-chain silver(I) coordination polymer: catena-poly[[[μ-aqua-aqua­disilver(I)]-bis­(μ3-5-methyl­pyrazine-2-carboxyl­ato)] dihydrate]

In the title silver(I) coordination polymer, {[Ag2(C6H5N2O2)2(H2O)2]·2H2O}n, the [Ag2(μ2-H2O)(H2O)] cores are extended by anti­parallel 5-methyl­pyrazine-2-carboxyl­ate (L) ligands, forming a novel double-chain structure. Both Ag+ cations show a distorted square-pyramidal coordination. Ag1 is bonded to two water molecules, one L N atom, one N atom and one carboxylate O atom from a neighbouring L, whereas Ag2 is surrounded by two L N atoms, two L carboxylate O atoms and one bridging water molecule. O—H⋯O hydrogen-bonding inter­actions involving water clusters and carboxyl­ate O atoms link the mol­ecules into a three-dimensional supra­molecular architecture, which is further consolidated by weak C—H⋯O inter­actions and π–π stacking inter­actions [centroid–centroid distance 3.643 (5) Å]

Recent Progress in Metal–Organic Framework (MOF) Based Luminescent Chemodosimeters

Metal–organic frameworks (MOFs), as a class of crystalline hybrid architectures, consist of metal ions and organic ligands and have displayed great potential in luminescent sensing applications due to their tunable structures and unique photophysical properties. Until now, many studies have been reported on the development of MOF-based luminescent sensors, which can be classified into two major categories: MOF chemosensors based on reversible host–guest interactions and MOF chemodosimeters based on the irreversible reactions between targets with a probe. In this review, we summarize the recently developed luminescent MOF-based chemodosimeters for various analytes, including H2S, HClO, biothiols, fluoride ions, redox-active biomolecules, Hg2+, and CN−. In addition, some remaining challenges and future perspectives in this area are also discussed

Nucleotide-based green synthesis of lanthanide coordination polymers for tunable white-light emission

White-light emitting lanthanide(iii) metal-organic coordination polymers (LMOCPs) were prepared via a green synthesis method performed in pure aqueous solution at room temperature without using toxic solvent and reagents. This kind of LMOCP, denoted as adenosine monophosphate (AMP)/Ln-CIP, was composed of Ln3+ {Ln = Tb (1), Eu (2), and Gd (3)}, hydrosoluble biomolecule of AMP, and nonpoisonous antenna ligand of CIP (ciprofloxacin). The complex of Tb(1), Eu(2), and Gd(3) in AMP/Ln-CIP emits strong green, red, and blue light, respectively. With careful adjustment of the doping mole ratio of the three lanthanide ions {Ln = Tb:Eu:Gd = 0.1:0.9:99.0} in one framework, white light-emission can indeed be achieved. AMP/Ln-CIP is network-structural and amorphous by transmission electron microscope and X-ray diffraction analysis. The fluorescence lifetime and quantum yield of AMP/Ln-CIP are 4.36 ms and 36.5%, respectively

Lateral Ge segregation and strain evolution in SiGe alloys during the formation of nickel germano-silicide on a relaxed Si073Ge 027 epilayer

Ge segregation and strain evolution in the SiGe alloys during the formation of nickel germano-silicide on a relaxed Si0.73Ge0.27 epilayer are studied in temperature range of 300-900°C. The continuous NiSiGe film on SiGe epilayer is formed at 500°C and below, which applies tensile stress on the underlying unreacted SiGe layer. When temperature rises to 600°C and above, the NiSiGe film begins to agglomerate, resulting in the formation of Ge-rich SiGe regions scattering among NiSiGe grains in the surface due to Ge lateral segregation from NiSiGe. During these processes, Ge is preferentially rejected from the NiSiGe grains giving rise to the transformation of NiSiGe to NiSi with increase of temperature and the increase of Ge content in the Ge-rich SiGe at the NiSiGe grain boundaries. The enlarged lattice constant of Ge-rich SiGe and the volume expansion of NiSiGe grains make the Ge-rich SiGe alloy under compressive strain. No significant Ge segregation is observed between Ni(SiGe) and the underlying SiGe layer even at higher temperature. ? 2013 AIP Publishing LLC

Lateral Ge segregation and strain evolution in SiGe alloys during the formation of nickel germano-silicide on a relaxed Si073Ge027 epilayer

National Basic Research Program of China [2012CB933503, 2013CB632103]; National Natural Science Foundation of China [61176092, 61036003, 60837001]; Ph.D. Programs Foundation of Ministry of Education of China [20110121110025]; Fundamental Research Funds for the Central Universities [2010121056]Ge segregation and strain evolution in the SiGe alloys during the formation of nickel germano-silicide on a relaxed Si0.73Ge0.27 epilayer are studied in temperature range of 300-900 degrees C. The continuous NiSiGe film on SiGe epilayer is formed at 500 degrees C and below, which applies tensile stress on the underlying unreacted SiGe layer. When temperature rises to 600 degrees C and above, the NiSiGe film begins to agglomerate, resulting in the formation of Ge-rich SiGe regions scattering among NiSiGe grains in the surface due to Ge lateral segregation from NiSiGe. During these processes, Ge is preferentially rejected from the NiSiGe grains giving rise to the transformation of NiSiGe to NiSi with increase of temperature and the increase of Ge content in the Ge-rich SiGe at the NiSiGe grain boundaries. The enlarged lattice constant of Ge-rich SiGe and the volume expansion of NiSiGe grains make the Ge-rich SiGe alloy under compressive strain. No significant Ge segregation is observed between Ni(SiGe) and the underlying SiGe layer even at higher temperature. (C) 2013 AIP Publishing LLC