title: A Benefit of Using the IDSCRF- over UFF-Radii Cavities and Why Joint Correlations of NMR Chemical Shifts Can Be Advantageous: Condensed Pyridines as an IEF-PCM/GIAO/DFT Case Study.
abstract: Herein, an advantage of the use of IDSCRF- over UFF-radii-based solute cavities in GIAO/DFT calculations is presented for the13C and especially15N NMR chemical shifts made for several bicyclic aromatic nitrogen heterocycles in CDCl3solution treated within the classical IEF-PCM solvation scheme. Successful application of the IDSCRF-radii in the non 1:1 joint multinuclear1H/13C and particularly1H/13C/15N correlations of the measured δH,C(,N)values to those obtained theoretically is also documented for a series of test systems (-268 ≤ δN≤ -72 ppm). The experimentally yet unknown δN's were found in this way for the title compounds via a trinuclear eq 1 determined for an optimally chosen value of the multiplication factor of initial raw δHdata (mH= 10). Such a simultaneous analysis of the δH,C(,N)data is proposed as a novel method to study the solution structure of the other similar conformationally homogeneous (bio)organic compounds. The issue of small spurious imaginary vibrational frequencies computed for a few molecular systems using the Gaussian 09 default UFF-radii is briefly considered as well.
authors.affiliation: Department of Theoretical and Structural Chemistry, Faculty of Chemistry, University of Łódź , Pomorska 163, 90-236 Łódź, Poland.
authors.forename: Ryszard B
authors.initials: RB
authors.lastname: Nazarski
authors.affiliation: Department of Organic and Applied Chemistry, Faculty of Chemistry, University of Łódź , Tamka 12, 91-403 Łódź, Poland.|Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux, IPREM, UMR CNRS 5254, Université de Pau et des Pays de l'Adour , 2 av. Président Pierre Angot, 64053 Pau Cedex 9, France.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Justyna
authors.affiliation: Department of Organic and Applied Chemistry, Faculty of Chemistry, University of Łódź , Tamka 12, 91-403 Łódź, Poland.
authors.forename: Stanisław
authors.initials: S
authors.lastname: Leśniak
authors.affiliation: Institut des Sciences Analytiques et de Physicochimie pour l'Environnement et les Matériaux, IPREM, UMR CNRS 5254, Université de Pau et des Pays de l'Adour , 2 av. Président Pierre Angot, 64053 Pau Cedex 9, France.
authors.forename: Anna
authors.initials: A
authors.lastname: Chrostowska