Two kinds of 1:1 manganese complexes a and b of bis(hexafluoroacetylacetonato)manganese(II)
coordinated with diazodi(4-pyridyl)methane (1) were prepared. Complexes a and b crystallize in the
orthorhombic space group Pbca and in monoclinic C2/c, respectively. Two pyridyl nitrogen atoms from two
different molecules of 1 are coordinated in the cis and trans configurations to the manganese ion to form
helical and zigzag infinite chains of octahedral manganese complexes in complexes a and b, respectively.
The magnetic susceptibilities (χmol) of both crystals before and after irradiation were measured on a SQUID
susceptometer and revealed χmol
T vs T plots characteristic of ferrimagnetic chains after irradiation for 97 h;
interaction between the manganese(II) ion and the photogenerated carbene is antiferromagnetic in both
complexes. The antiferromagnetic exchange coupling parameters (J) in the photolyzate of complex a and b
were estimated by a theoretical treatment through a procedure of extrapolation by using small rings to be J/k
B
= −34.8 ± 0.8 and −24.4 ± 0.5 K, respectively. Maximum χmol
T values of 210 at 5 K for cis- and 246
emu·K·mol-1 at 1.9 K for trans complexes correspond to correlation lengths of 186 and 218 manganese−carbene S = 3/2 units, respectively.
The concentrations of several D-amino acids have been reported to significantly increase in the plasma of patients with chronic kidney disease (CKD). However, the amounts of these D-amino acids are low (around 1% of the Lform or lower), and their analyses were complicated by various interfering compounds in many clinical samples. A highly selective analytical method is thus required to perform the accurate and precise determination of these D-amino acids in the plasma of CKD patients. In the present study, a selective 3D-HPLC system equipped with reversed-phase, anionexchange, and enantioselective columns has been designed and developed for the determination of the asparagine, serine, alanine and proline enantiomers. For the sensitive analysis, amino acids were precolumn derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole and detected by their fluorescence. The system was validated by using human plasma in addition to the standard amino acids, and results with a sufficient linearity, precision, and accuracy were obtained. The 3D-HPLC system was applied to the plasma of patients with different stages of CKD and all of the target D-amino acids were clearly observed without interferences for all 25 tested patients. Good correlations were shown between the kidney function of the patients and the %D values of the target analytes, especially D-Asn and D-Ser, indicating that the present 3D-HPLC method is useful for the sensitive diagnosis of CKD.
For the enantioselective and simultaneous analysis of lactate and 3-hydroxybutyrate, a validated online two-dimensional high-performance liquid chromatography system using 4-nitro-7-piperazino-2,1,3-benzoxadiazole as a fluorescent derivatization reagent has been developed. For the reversed-phase separation in the first dimension, a Capcell Pak C18 ACR column (1.5 × 250 mm, particle size 3 μm) was used, and the target fractions were isolated by their hydrophobicity. In the second dimension, a polysaccharide-coated enantioselective column, Chiralpak AD-H (2.0 × 250 mm, 5 μm), was used. The system was validated by the calibration curve, intraday precision, interday precision, and accuracy using standards and real human samples, and satisfactory results were obtained. The present method was applied to human plasma and urine, and in the plasma, trace amounts of d-lactate (8.4 μM) and l-3-hydroxybutyrate (1.0 μM), besides high levels of l-lactate (860.9 μM) and d-3-hydroxybutyrate (59.4 μM), were successfully determined. In urine, trace levels of d-lactate (3.7 μM), d-3-hydroxybutyrate (2.3 μM), and l-3-hydroxybutyrate (3.3 μM) in addition to a relatively large amount of l-lactate (15.4 μM) were observed. The present online two-dimensional high-performance liquid chromatography system is useful for the simultaneous determination of all the lactate and 3-hydroxybutyrate enantiomers in human physiological fluids, and further clinical applications are ongoing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.