1H-driven 19F spin diffusion and cross polarization measurements for distance and structure determination in ciprofloxacin derivatives

Y. GARRO LINCK; A. K. CHATTAH; C. B. ROMAÑUK; M. E. OLIVERA; R. H. MANZO; S. CUFFINI; J. RAYA; J. HIRSCHINGER; G. A. MONTI

EUROMAR

Congreso; EUROMAR 2009; 2009

EUROMAR

Dipolar-driven spin diffusion solid state NMR (Nuclear Magnetic Resonance) is a robust approach for obtaining semi-quantitative homonuclear distances. We applied the centerband-only detection of exchange (CODEX) technique, which is based on 1H driven anisotropic spin diffusion. [REF codex] on a new pharmaceutical compound, ciprofloxacin saccharinate[ref: JPS], This compound exhibits polymorphism and presents forms I and II, where form II could be obtained as a monocrystal. We used crystallographic data obtained from single crystal diffraction of form II as a starting point to performed the fittings of CODEX data. Taking into account the value of F(0) (overlap integral) obtained from form II we were able to determine distances and molecules per unit cell in the form I. Form II presents two molecules per unit cell (one in the assymetric unit) with different orientations, on the other hand, form I shows at least two molecules per asymmetric unit. Results from CODEX, 19F spectrum and TF1 experiments performed on form II give us evidence that form I could be the mixture of two polymorphs, one of them probably the form II. We also performed 1H-19F CP-MAS (Cross Polarization - Magic Angle Spinning) experiments with variable contact time to determine internuclear distances 1H-19F.