1-(4-Hydroxyphenyl)pentan-1-one

Luo, Z.; Zhu, Hongjun; Liu, Shan

doi:10.1107/s1600536806040694

Cited by 1 publication

(12 citation statements)

References 3 publications

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“…No significant differences were noted when the molecular structure of HVP form I obtained at 167 K was compared with that published 33 8) chains (Figure 6). Decreasing the temperature to 167 K does not lead to significant changes in crystal packing.…”

Section: As Shown In Tablementioning

confidence: 89%

“…As mentioned in the Introduction, prior to this work only the structure of form I at 298 ± 2 K (CSD ref code: KERPUT) 12 was known. 33 Evidence for the likely existence of form II was available from thermal analysis results, but the corresponding crystal structure had not been determined, and form III had not been identified. 43 The structural characterization of these two new HVP polymorphs became possible when, in the course of this work, it was found that (i) crystals of form II suitable for SCXRD analysis could be produced by crystallization from the melt and that (ii) it was possible to generate form III by cooling a form II crystal below 247 K (i.e., the II → III phase transition occurs under single crystal to single crystal conditions).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…This led us to embark on the study of the HOC 6 H 4 C(O)R (R = H, n-alkyl) family, where the molecular structures differ solely by the length of the R alkyl group chain, and for which, at the outset (around 2007), no prior detection of polymorphism had been reported, albeit individual structures existed for R = H, 30 CH 3 , 31 C 3 H 7 , 32 and C 4 H 9 . 33 A crystal engineering rationale suggested that, regardless of the possible existence multiple crystal forms, a common tendency toward a molecular packing based on one-dimensional C 1 1 (8) chains sustained by a OH•••OC hydrogen bond motif should be expected for the whole family. This could indeed be confirmed by the available data (R = H, 30 CH 3 , 31 C 3 H 7 , 32 and C 4 H 9 ).…”

Section: ■ Introductionmentioning

confidence: 99%

“…This could indeed be confirmed by the available data (R = H, 30 CH 3 , 31 C 3 H 7 , 32 and C 4 H 9 ). 33 However, more subtle aspects such as the impact of differences in molecular conformation (e.g., OH and CO groups in E or Z conformation) and alkyl chain length, and flexibility, in the conceivable formation of distinct polymorphs were not predictable.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In this context, a combined experimental and theoretical approach to polymorphism comprising structural, thermodynamic, and kinetic perspectives, and relying on families of compounds with systematic differences in molecular structure seems particularly interesting for two main reasons: (i) to provide experimental evidence of how specific alterations in a molecular framework impact on packing patterns, stability relationships, and dynamics of transformation between different forms; (ii) to offer a series of sufficiently accurate experimental data that can serve as benchmarks for the validation and refinement of theoretical models used in the investigation of polymorphism. This led us to embark on the study of the HOC 6 H 4 C(O)R (R = H, n -alkyl) family, where the molecular structures differ solely by the length of the R alkyl group chain, and for which, at the outset (around 2007), no prior detection of polymorphism had been reported, albeit individual structures existed for R = H, CH 3 , C 3 H 7 , and C 4 H 9 …”

Section: Introductionmentioning

confidence: 99%

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Conformational and Nonconformational Polymorphism in 4′-Hydroxyvalerophenone: A Structure–Energetics–Dynamics Perspective

Simões

Lopes

Piedade

et al. 2020

Crystal Growth & Design

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Compounds based on the HOC6H4C(O)R (R = H, alkyl, OH, etc.) framework have provided excellent models to investigate the complex interplay of structural and energetic effects behind polymorphism and crystallization as a whole. In this work, the polymorphic behavior of 4′-hydroxyvalerophenone (HVP, R = C4H9) was experimentally and theoretically explored from a holistic structural–energetics–dynamics perspective. The molecular and crystal structures of two new forms (II and III) were determined by single crystal X-ray diffraction. They share with the previously known form I, and with analogous systems (R = H, CH3) that do not contain a flexible R group, an infinite C 1 1(8) chain sustained by “head-to-tail” OH···OC hydrogen bonds as the main one-dimensional (1D) packing motif. The molecular organization within the chain (“herringbone” type in form I and planar in forms II and III) and the relative orientation of the CO and OH groups (Z in form I and E in forms II and III) are, however, different. These differences are reflected by the thermodynamic and kinetic relationships between the three polymorphs. Differential scanning calorimetry and microscopy experiments revealed that (i) the structurally very similar III/II pair is enantiotropically related by a fast and reversible phase transition at 247.5 ± 0.4 K. (ii) In contrast, the form II → form I transition is severely hindered, and, although form II is monotropic relative to form I, it can be observed to melt upon heating, or stored for days at ambient pressure and temperature without signs of transformation to form I, unless subjected to a perturbation (e.g., scratching, grinding). These findings are consistent with microscopy and molecular dynamics (MD) simulation results, suggesting that the III → II transition occurs by a concerted displacement of the molecules in the crystal lattice, while the II → I process is compatible with a diffusive nucleation and growth mechanism. It was also found that, despite being metastable, form II preferentially crystallizes from the melt in accordance with Ostwald’s rule of stages. MD simulations indicated that this observation is most likely originated by the fact that the structure of liquid HVP is much closer to form II than to form I. Finally, a thermodynamic analysis suggested that the relative stability of the three HVP polymorphs, at 298 K, ranked in terms of Gibbs energy (I > II > III) does not follow the corresponding lattice enthalpy trend (I > III > II). This stresses the importance of accounting for entropy contributions when discussing polymorph stability.

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Section: As Shown In Tablementioning

confidence: 89%