Rare Earth Complexes of Aminopolycarboxylic Acid Ⅱ.Synthesis and Structure of Lanthanum Complex of Dipicolinic Acid

Complexes of the general formula,(Me_4N)_2[(Ln(HDPA)_2(DPA)]·Cl,have been synthesized,where Ln=La,Ce,Pr,Nd,Sm and H_2DPA=dipicolinic acid.Among them,the crystal structure of the La complex has been determined by a four-circle X-ray diffractometer to a final R value of 0.080.The crystal is orthorhombic,space group Pccn with a=1.0321(1),b=1.4951(2),c=2.0766(6)nm,V=3.2044(9)nm^3,and Z=4.The rare earth ion is nine coordinated to forming a tortuous tricapped trigonal prism.

Anthrax Biomarker:a Fluorescent Probe for Dipicolinic Acid Using Eu(Ⅲ)-doped Nanosheets

A novel two-dimensional nanosheet fluorescent probe embedded with rare earth Eu(Ⅲ)was developed to detect dipicolinic acid(DPA),a biomarker of Bacillus anthracis bacterial spores.DPA,a major component of Bacillus anthracis spores which were highly toxic to humans,was not found in other common bacteria.The ability to detect ultra-low concentrations of DPA would therefore be of great significance.Eu(Ⅲ)-doped ytterbium hydroxide nanosheets were obtained by mechanical exfoliation from layered rare-earth hydroxide(LRH)materials.The crystallinities,layered structure and morphology of the as-synthesized nanosheets were studied by power X-ray diffraction,transmission electron microscopy and atomic force microscopy.Eu(Ⅲ)emission increased linearly with DPA addition in the range of 0.1~30μmol/L.Based on the antenna effect,the detection limit of DPA was 0.078μmol/L and much lower than the infective dose of Bacillus anthracis in humans of 60μmol/L.The nanosheet fluorescent probe exhibited good specificity toward DPA,and the interferences with selected aromatic ligands and amino acids were observed to be negligibly small in comparison with that of DPA.Our findings provide a basis for the application of Eu(Ⅲ)-doped nanosheets for accurate,sensitive,and selective monitoring of DPA as a biomarker of anthrax.

Synthesis and Crystal Structure of {Cu_2(pdc)_2(4,4'-bipy)(H_2O)·3H_2O}_2

The title compound {Cu2(pdc)2(4,4?-bipy)(H2O)3H2O}2 1 (H2pdc = pyridine-2,6- dicarboxylic acid, also known as dipicolinic acid; 4,4?-bipy = 4,4?-bipyridine) has been synthesized by the hydrothermal reaction and its structure was determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group Pi with a = 7.2278(3), b = 10.6259(4), c = 17.7614(6) ? a = 79.5990(10), = 83.6300(10), ? = 71.8280(10)o, V = 1272.60(8) ?, C48H44Cu4N8O24, Mr = 1371.07, Z = 1, Dc = 1.789 g/cm3, = 1.747 mm-1, F(000) = 696, R = 0.0397 and wR = 0.1137 for 3938 observed reflections (I > 2s(I)). There are two kinds of Cu coordination environments, and each central copper(II) atom is five-coordinated in a distorted square-based pyramidal coordination geo- metry. Four copper(II) atoms are linked by four pdc and two 4,4?-bipy ligands to form an annular rectangle structure. Extensive hydrogen-bonding interactions involving carboxylate O atoms as well as coordinated and free water molecules lead to the formation of a three-dimensional network struc- ture.