Portal de Periódicos da CAPES

Characterization and structure by NMR and FTIR spectroscopy, and molecular modeling of chromium(III) picolinate and nicotinate complexes utilized for nutritional supplementation

1997; Elsevier BV; Volume: 66; Issue: 2 Linguagem: Inglês

10.1016/s0162-0134(96)00192-4

1873-3344

C. Leigh Broadhurst, Walter Schmidt, James B. Reeves, Marilyn M. Polansky, K Gautschi, Richard A. Anderson,

Adsorption and biosorption for pollutant removal

Chromium picolinate (CrPic) and chromium nicotinate preparations (CrNic1, CrNic2, CrNic3) were investigated with 1H and 13C NMR, FTIR, and molecular modeling. CrPic is crystalline and bidentately coordinated. CrPicA bonding broadens the NMR signal or shifts it so far downfield that it is not detectable. All CrNic preparations are noncrystalline, and results provide no evidence that nicotinic acid (NiA) is O-coordinated to Cr. The complex colors may be due to O-coordination with H2O and/or OH, not NicA. 1H NMR spectra of CrNic1 have two sets of peaks. One set has a significant δ with respect to NicA, indicating that NicA is more strongly associated with Cr. CrNic1 13C data show small, uniform δ with respect to NicA, indicating that strong localized CrCOOH bonding is unlikely. The magnitude of δ, 13C, and 1H exchange data suggests that limited CrN bonding may occur in CrNic1. CrNic2 and CrNic3 show little difference from NicA spectra. FTIR spectra of all CrNic complexes, but not CrPic, PicA, or NicA, show bound OH and/or H2O. CrNic complexes are probably olates, with Cr and NicA OH-polymerized. CrPic exchanges with CrNic1 in DMSO. This exchange may provide a mechanism for the absorption and active transport of Cr in biological systems.