title: Chromium(III) complexes as intermolecular probes.
abstract: Metal ion complexes provide flexible paramagnetic centers that may be used to define intermolecular contacts in a variety of solution phase environments because both the charge and electronic relaxation properties of the complex may be varied. For most complex ions, there are several proton equilibria that may change the effective charge on the complex as a function of pH which in turn affects the efficacy of application for defining the electrostatic surfaces of co-solute molecules. We report here spectrophotometric and nuclear spin relaxation studies on aqueous solutions of chromium(III) complexes of EDTA, DTPA, and bis-amides of both. The effective charges available from these paramagnetic centers range from -3 to +1 and we report the pH ranges over which the effective charge is defined with confidence for application in magnetic relaxation experiments.
authors.affiliation: Chemistry Department, University of Virginia, Charlottesville, VA 22904-4319, USA.
authors.forename: Galina
authors.initials: G
authors.lastname: Diakova
authors.forename: Zachary
authors.initials: Z
authors.lastname: Fuller
authors.forename: Ken
authors.initials: K
authors.lastname: Victor
authors.forename: Koichi
authors.initials: K
authors.lastname: Fumino
authors.forename: R G
authors.initials: RG
authors.lastname: Bryant
mesh_terms: D000465:Algorithms; D002857:Chromium / Q000032:analysis* / Q000737:chemistry*; D004492:Edetic Acid / Q000032:analysis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015336:Molecular Probe Techniques; D004369:Pentetic Acid / Q000032:analysis* / Q000737:chemistry
chemical_list: D002857:Chromium; D004369:Pentetic Acid; D004492:Edetic Acid