Determination of a complex crystal structure in the absence of single crystals: analysis of powder X-ray diffraction data, guided by solid-state NMR and periodic DFT calculations, reveals a new 2′-deoxyguanosine structural motif

Abstract

A multi-technique strategy reveals a new hydrogen-bonding motif for a 2′-deoxyguanosine derivative.

Conformations in Solution and in Solid-State Polymorphs: Correlating Experimental and Calculated Nuclear Magnetic Resonance Chemical Shifts for Tolfenamic Acid

“…One alternative diffraction-based approach is to try and solve the structure from powder xray diffraction (PXRD), but this can often be difficult and typically results in many putative structural models that are consistent with the powder diffractogram. [1][2][3][4] NMR crystallography, [5][6][7][8][9][10][11][12][13][14] the combined use of solid-state NMR data and ab initio calculation of NMR parameters, is now widely used in academia and increasingly in industry as a complementary tool for crystal structure determination. It is useful for refining and improving the quality of structural models based on both SXRD and PXRD data.…”

A theoretical NMR study of selected benzazoles: Comparison of GIPAW and GIAO‐PCM (DMSO) calculations

“…At the present time, gauge-including-projected-augmented-wave (GIPAW) calculations are the standard ones to simulate the results obtained by solid-state NMR. [1][2][3][4][5] However, in previous papers, we have been successful in obtaining acceptable results using gauge-invariant atomic orbital/Becke, 3-parameter, Lee-Yang-Parr (GIAO/ B3LYP)/6-311++G(d,p) calculations together with dimethyl sulfoxide (DMSO) and polarizable continuum model (PCM; continuum solvent model). [6][7][8][9][10] Thus, establishing that DMSO is the best solvent to simulate the effects of the solid-state.…”

Synthesis and structural characterization of cocrystals of isoniazid and cinnamic acid derivatives

“…Individual 13 C chemical shifts were observed to distinguish between alternative hydrogen bonding arrangements, which may provide valuable constraints in cases where the structure needs to be solved from PXRD data. [48] Synthesized cocrystals might be able to replace INH in the existing FDCs used to treat TB by expected mitigation of degradation of RIF and INH from hydrazone formation by masking the key hydrazide group through cocrystallization. This study also renders an opportunity to combine INH with an antioxidant in a single tablet.…”