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Crystal Growth and Design
Volumn 9, Issue 2, 2009, Pages 853-857
Lessons on the discovery and assignment of polymorphs, highlighted by the case of the latent pigment DPP-Boc
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EID: 61749091130     PISSN: 15287483     EISSN: 15287505     Source Type: Journal    
DOI: 10.1021/cg800466x     Document Type: Article
Times cited : (13)
References (41)
  • 14
    • 61749097908 scopus 로고    scopus 로고
    • Results made available to the authors of ref 5 in the course of their collaborative research with Ciba Specialty Chemicals.
    • Results made available to the authors of ref 5 in the course of their collaborative research with Ciba Specialty Chemicals.
  • 21
    • 85088006668 scopus 로고    scopus 로고
    • The main differences between the structures concern some of the torsion angles τ2-τ4 that define the conformation of the t-butoxycarbonyl group, which differ in some cases by up to ca. 30° between the two structures
    • 4 that define the conformation of the t-butoxycarbonyl group, which differ in some cases by up to ca. 30° between the two structures.
  • 22
    • 61749103751 scopus 로고    scopus 로고
    • Ref 7 misrepresents the discussion of the structure of the α polymorph in the earlier paper by stating that the molecular stack is described as A-B-A-B-, whereas ref 5 actually states that the stacking comprises groups of three molecules stacked as ⋯A·S· ⋯A·S·A⋯A·S·A⋯.
    • Ref 7 misrepresents the discussion of the structure of the α polymorph in the earlier paper by stating that "the molecular stack is described as A-B-A-B-", whereas ref 5 actually states that the stacking comprises "groups of three molecules stacked as ⋯A·S· ⋯A·S·A⋯A·S·A⋯".
  • 24
    • 61749083745 scopus 로고    scopus 로고
    • Some of the erroneous statements concerning polymorph assignment in ref 10 are also repeated in a subsequent paper (which is focused on studies of the transformation of DPP-Boc to DPP rather than the structural properties of polymorphs of DPP-Boc, Ref 12 also refers to the method for structure determination of the β polymorph as a simulation of the structure. We emphasize that the techniques for carrying out direct-space structure solution from powder X-ray diffraction data are not computer simulation techniques based on calculation of energies of crystal structures. Instead, these techniques carry out structure solution directly (and solely) from consideration of the experimental powder X-ray diffraction data, and in the methodology used in our work reported in ref 5, no calculation of the energies of trial crystal structures was involved. Details of techniques for direct-space structure solution from powder X-ray diffraction data are described elsewhere
    • Some of the erroneous statements concerning polymorph assignment in ref 10 are also repeated in a subsequent paper (which is focused on studies of the transformation of DPP-Boc to DPP rather than the structural properties of polymorphs of DPP-Boc). Ref 12 also refers to the method for structure determination of the β polymorph as a "simulation of the structure". We emphasize that the techniques for carrying out direct-space structure solution from powder X-ray diffraction data are not computer simulation techniques based on calculation of energies of crystal structures. Instead, these techniques carry out structure solution directly (and solely) from consideration of the experimental powder X-ray diffraction data, and in the methodology used in our work reported in ref 5, no calculation of the energies of trial crystal structures was involved. Details of techniques for direct-space structure solution from powder X-ray diffraction data are described elsewhere.
  • 29
    • 0004060848 scopus 로고    scopus 로고
    • David, W. I. F, Shankland, K, McCusker, L. B, Baerlocher, C, Eds, OUP/IUCr
    • (d) David, W. I. F.; Shankland, K.; McCusker, L. B.; Baerlocher, C., Eds., Structure Determination from Powder Diffraction Data, OUP/IUCr, 2002.
    • (2002) Structure Determination from Powder Diffraction Data
  • 37
    • 61749090694 scopus 로고    scopus 로고
    • The possibility that the β polymorph is only formed upon sample grinding, prior to recording the powder X-ray diffraction data, may be eliminated as powder X-ray diffraction patterns recorded for both ground and unground samples were identical to that of the β polymorph shown in Figure 3b (except for minor differences in relative peak intensities that are completely attributed to the effects of slight preferred orientation).
    • The possibility that the β polymorph is only formed upon sample grinding, prior to recording the powder X-ray diffraction data, may be eliminated as powder X-ray diffraction patterns recorded for both ground and unground samples were identical to that of the β polymorph shown in Figure 3b (except for minor differences in relative peak intensities that are completely attributed to the effects of slight preferred orientation).
  • 38
    • 61749101660 scopus 로고    scopus 로고
    • It seems likely that the slow crystallization conditions reported in ref 10 may be important for promoting the production of the new γ polymorph, rather than the α and β polymorphs reported previously
    • It seems likely that the slow crystallization conditions reported in ref 10 may be important for promoting the production of the new γ polymorph, rather than the α and β polymorphs reported previously.
  • 39
    • 85088003732 scopus 로고    scopus 로고
    • 2.
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* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.