Spin Crossover Behavior of FeII Complexes Bridged by Thiophene-Functionalized Triazole Ligands with Different Sizes and Rigidities

Four thiophene functionalized triazole ligands (L1=4-(thenyl)-1,2,4-triazole, L2=4-(thiophene ethyl)-1,2,4-triazole, L3=N-Thiophenylidene-4H-1,2,4-triazole-4-amine, and L4=(4-[(E)-2-(5-sulfothiophene)vinyl]-1,2,4-triazole) were synthesized. These ligands have different lengths and rigidities, while ligand L4 has a sulfonic acid group that can form a hydrogen bond. Five 1D Fe^II chain complexes were synthesized: [Fe(L1)₃](X)₂ ⋅ nH₂O [X=BF₄⁻, n=1.5 ( C1 ); X=ClO₄⁻, n=1 ( C2 )], [Fe(L2)₃](BF₄)₂ ⋅ 1.5H₂O ( C3 ); [Fe(L3)₃](X)₂ ⋅ nH₂O [X=BF₄⁻, n=2 ( C4 ); X=ClO₄⁻, n=2.5 ( C5 )]. The results of temperature-dependent magnetic susceptibility reveal that complexes C1 , C2 , and C3 experienced the transition between two spin states. And C4 and C5 maintain high spin states at all temperature ranges. Binuclear complex [Fe₂(L3)₅(SCN)₄] ( C6 ) and mononuclear material [Fe(L4)₂(H₂O)₄] ⋅ 2H₂O ( C7 ), these two zero-dimensional molecules were also synthesized. They all display weak antiferromagnetic exchange coupling and a high spin state in the whole process.     

Determination of cadmium copper, iron, nickel, lead and zinc in crawfish [Procambrus clarkii] by inductively coupled plasma optical emission spectrometry: a study over the 2009 season in Southwest Louisiana

Following a mini-review of crawfish aquaculture, the concentrations (mean in micrograms of analyte per gram of dried sample ± 95% confidence interval, range) determined by inductively coupled plasma-optical emission spectrometry of cadmium (0.49 ± 0.14, 0.34-0.79 ), copper (34.9 ± 5.3, 23.8-44.2), nickel (1.83 ± 0.54, 1.08-3.39), lead (18.0 ± 4.0, 9.9-23.), iron, and zinc (47.3 ± 4.6, 41.3-55.8) were relatively constant with a slight increase in iron (620.4 ± 205.8, 328.8-1072.8) in whole crawfish in a season of 4 months (February through May 2009) in Southwest Louisiana. The temperature of the crawfish ponds was monitored weekly but had no effect on the metal concentration in the crawfish trial. The copper and zinc concentrations in the crawfish pond soil decreased with increasing temperature. The other four metals showing no effect of temperature variations (increase). A comparison with a previous study showed no significant changes in the metal concentrations in the crawfish.