Fluorescent sensing platform based on green luminescence carbon dots and AuNPs for clenbuterol detection in pork liver.

In this paper, water-soluble green fluorescent carbon dots (G-CDs) were prepared using p-phenylenediamine and glutathione (GSH) as the precursors. The G-CDs exhibit excellent optical properties, and the maximum emission wavelength is located at 522 nm (under 410 nm excitation), which greatly overlaps with the absorption spectrum of AuNPs. Consequently, an effective "off-on" fluorescent sensing platform involved in G-CDs and AuNPs for detection of clenbuterol (CLB) was constructed. The fluorescence of G-CDs was strongly quenched by AuNPs due to the inner filter effect (IFE). As CLB was introduced, the quenched fluorescence intensity was recovered due to the specific interaction between the AuNPs and CLB. The recovered fluorescence intensity is linear to CLB concentration in the range of 13-270 ng mL-1 with a low detection limit of 3.75 ng mL-1. The prepared sensor has been successfully applied for CLB detection in pork liver and could be utilized in food analysis.

Poly[[diaquadi-µ(2)-cyanido-bis-(µ(2)-pyrazine-2-carboxyl-ato)dicopper(I)copper(II)] dihydrate].

In the title compound, {[Cu(II)Cu(I) (2)(C(5)H(3)N(2)O(2))(2)(CN)(2)(H(2)O)(2)]·2H(2)O}(n), the Cu(II) atom lies on an inversion centre and is octa-hedrally coordinated by two N atoms and two O atoms from opposing pyrazine-2-carboxyl-ate (2-pac) ligands and two water O atoms. The Cu(I) atom has a triangular geometry, coordinated by one N atom and one C atom from two bridging cyanide ligands, and another N atom from the 2-pac ligand. The three-dimensional structure features a succession of two-dimensional sheets containing [Cu(CN)](n) chains linked by Cu(2-pac)(2)(H(2)O)(2) groups. The coordinated and free water mol-ecules are involved in an extended three-dimensional hydrogen-bond network with the 2-pac ligands.

Bis(3-amino-pyrazine-2-carboxyl-ato-κN,O)diaqua-manganese(II).

The Mn(II) atom in the title compound, [Mn(C(5)H(4)N(3)O(2))(2)(H(2)O)(2)], exhibits an octa-hedral geometry comprising the two O atoms and two N atoms from two 3-amino-pyrazine-2-carboxyl-ate ligands, which act as chelating ligands, and two water mol-ecules. An intra-molecular N-H⋯O hydrogen bond occurs. In the crystal, N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds link adjacent mol-ecules into a three-dimensional network. The mol-ecule lies on a twofold rotation axis.