Untitled

Abstract

The theory of solid-state nuclear magnetic resonance (NMR) spectroscopy is reviewed, with specific discussions of magnetic interactions in the solid state. Each magnetic interaction (Zeeman, dipole-dipole, chemical-shift, spin-spin, and quadrupolar) is addressed and manifestations of these interactions in the solid state NMR spectrum are explained. The techniques of high-power decoupling, magic-angle spinning, and cross-polarization, used to acquire highly resolved solid-state NMR spectra, are also illustrated. Application of solid-state NMR to pharmaceutical problem solving and methods development is then briefly reviewed.

Solid-State Carbon NMR Characterization and Investigation of Intrinsic Dissolution Behavior of Fluconazole Polymorphs, Anhydrate Forms I and II

“…These spectral differences in these regions could indicate different chemical environments, producing differing levels of the de-shielding effect of the electronic density, accompanied by differences in some molecular interactions and crystal symmetry. 21) SSNMR spectroscopy can be used to estimate the number of molecular conformations, as well as the configurational differences, in a portion of the molecule. 22,23) The 13 C-SSNMR spectra of anhydrate form II shows only one peak per carbon atom with no peak splitting.…”

Polymorphic Characterization of Pharmaceutical Solids, Donepezil Hydrochloride, by13C CP/MAS Solid-State Nuclear Magnetic Resonance Spectroscopy

“…All spectra were obtained using a combination of the CP/MAS and total sideband suppression (TOSS) methods (CP/MAS/TOSS). In the 1 H/ 13 C CP/MAS/TOSS experiments, the Hartmann-Hahn polarization transfer with a contact time of 2 ms was optimized to operate at B1 field strengths of 59.5 kHz and 40.0 kHz for the 1 H and 13 C channels, respectively. [20][21][22][23] Two-pulse phasemodulation (TPPM) proton decoupling was used to improve the proton decoupling with the two pulses each with a flip angle of 10.0 µs and a phase difference of 15 o between pulses.…”

“…13 This technique is usually non-destructive and non-invasive. In addition, the samples to be analyzed require no special preparation.…”

Characterization of Polymorphs of a Novel Quinolinone Derivative, TA-270 (4-Hydroxy-1-methyl-3-octyloxy-7-sinapinoylamino-2(1H)-quinolinone).

“…Internal Structure of Polymorphs Solid state 13 C-NMR spectroscopic studies were employed to gain insight into the internal structure of the TA-270 polymorphs. Figure 6 shows 13 C-NMR spectra for the a-, b-, and d-forms measured in a CP-MAS mode.…”

“…There can be large differences in their physical properties and also differences in bioavailability. 7,8) Several techniques for solid state measurements have been reported in the study of polymorphs: microscopy, infrared (IR) spectroscopy, 9) differential scanning calorimetry (DSC), [10][11][12] powder X-ray diffractometry, 13,14) and solid state NMR spectroscopy. [15][16][17][18][19][20][21] In the present study, the characterization of various crystalline forms of TA-270 was examined as a preformulation study.…”