Structure of pentoxifylline, C₁₃H₁₈N₄O₃

Multicomponent pharmaceutical cocrystals: furosemide and pentoxifylline

“…C8- N15-C16-C17 N15-C16-C17-O18 C6-C5-S1-N2 N29-C28-C27-C26 Reference (CSD refcode) Pentoxifylline, form I 75.6 (3) Pavelčík et al (1989) H atoms bound to C atoms and the carboxy group were positioned geometrically, with C-H = 0.93-0.97 Å and O-H = 0.82 Å , and refined as riding, with U iso (H) = 1.2 or 1.5U eq (C,O). H atoms bound to N atoms were included in positions identified from difference Fourier maps and were then refined as riding, with U iso (H) = 1.2U eq (N).…”

“…Besides the pharmaceutical importance of the cocrystals obtained, it was interesting to observe the influence of the crystal environment on the molecular conformations of the furosemide and pentoxifylline molecules by comparison of the corresponding conformations in single-and multicomponent crystal structures. There are two polymorphic forms of pentoxifylline reported in the literature, namely triclinic (Pavelčík et al, 1989) and monoclinic (Stepanovs & Mishnev, 2011), and three polymorphic forms of furosemide have been reported by Lamotte et al (1978) and Babu et al (2010). One can see that in (I)-(III), the pentoxifylline molecule adopts a conformation close to that in the monoclinic form, while the torsion angles of furosemide vary over a wide range (Table 1).…”

Patterson-oriented automatic structure determination. Organic structures

“…(c) Test distributed with SHELXL93 (Sheldrick, 1993). (d) Pavelcik et al (1989). (e) Kettmann et al (1985).…”

“…Crystal data for test structures and results of automatic solution and isotropic re®nement SOLV gives the strategy number. SOLV 0 is a strategy used for solving heavy-atom structures (Pavelcik, 1994 ² (a) For the sake of brevity see Pavelcik et al (1992) and Pavelcik (1994). (b) Altomare et al (1993).…”

“…Recently (Pavelcik, 1988(Pavelcik, , 1994(Pavelcik, , 1997Pavelcik et al, 1992) powerful Patterson methods for the automatic determination of heavy-atom structures have been developed. These methods are combined with Fourier recycling methods, which are very powerful tools for phase re®nement (Pavelcik, 1994; see also Kinneging & de Graaf, 1984;Miller et al, 1994;Sheldrick & Gould, 1995).…”