title: Coupled hydrogen-bonding interactions between beta-carboline derivatives and acetic acid.
abstract: In this work, we have analysed the tendency of two beta-carboline derivatives, harmane and norharmane, in the formation of hydrogen bonds. We obtained the (1)H and (13)C NMR spectra of different mixtures of these derivatives with acetic acid (AcOH) in CDCl(3). A cyclic 1:3 complex is proposed between harmane and AcOH, while a 1:2 complex is proposed for norharmane. Chemical shifts at temperatures between 233 and 323 K were measured: lowering the temperature produces the same effect as increasing the amount of AcOH in solution. The (13)C data confirm a delocalisation of the pi electron density towards the pyridinic ring that occurs when AcOH is added.
authors.affiliation: University Autónoma de Madrid, Department Quimica Física Aplicada, Cantoblanco, Madrid, 28049, Spain. dolores.reyman@uam.es
authors.forename: D
authors.initials: D
authors.lastname: Reyman
authors.forename: F
authors.initials: F
authors.lastname: Hallwass
authors.forename: Simone M da Cruz
authors.initials: SM
authors.lastname: Gonçalves
authors.forename: J J
authors.initials: JJ
authors.lastname: Camacho
mesh_terms: D019342:Acetic Acid / Q000737:chemistry*; D002243:Carbolines / Q000737:chemistry*; D006247:Harmine / Q000031:analogs & derivatives / Q000737:chemistry; D006860:Hydrogen Bonding; D007211:Indoles / Q000737:chemistry; D015394:Molecular Structure; D011725:Pyridines / Q000737:chemistry; D013696:Temperature
chemical_list: D002243:Carbolines; D007211:Indoles; D011725:Pyridines; D006247:Harmine; C030374:indole; C010262:norharman; C023666:pyridine; D019342:Acetic Acid