A Whole Output Strategy for Polymorph Screening:  Combining Crystal Structure Prediction, Graph Set Analysis, and Targeted Crystallization Experiments in the Case of Diflunisal

2003 ◽  
Vol 3 (2) ◽  
pp. 151-158 ◽  
Author(s):  
Wendy I. Cross ◽  
Nicholas Blagden ◽  
Roger J. Davey ◽  
Robin G. Pritchard ◽  
Marcus A. Neumann ◽  
...  
Author(s):  
Pawanpreet Singh ◽  
Renu Chadha

Molecular simulation is increasingly used by medicinal chemists in the process and product development. Reliable computational predictions are of great value not only for the design of an active pharmaceutical ingredient with novel properties but also for the avoidance of an undesirable change of form in the late stages of development of an industrially important molecule. In the pharmaceutical industry, drug polymorphism can be a critical problem and is the subject of various regulatory considerations. This contribution tried to review the fuzzy frontiers between the chemical structure of the molecule and its crystal energy landscape with a particular focus on the crystal structure prediction (csp) methodology to complement polymorph screening. A detailed application of csp in the pharmaceutical industry is illustrated on ciprofloxacin; describing its putative polymorphs. This approach successfully identifies the known crystal form within this class, as well as a large number of other low-energy structures. The performance of the approach is discussed in terms of both the quality of the results and computational aspects. csp methods are now being used as part of the interdisciplinary range of studies to establish the range of solid forms of a molecule. Moreover, further methodological improvements aimed at increasing the accuracy of the predictions and at broadening the range of molecules i.e. cocrystals, salts and solvates.


2014 ◽  
Vol 70 (a1) ◽  
pp. C1615-C1615
Author(s):  
Sarah Price

Crystal Structure Prediction (CSP) algorithms aim to generate the thermodynamically feasible crystal structures of a molecule from the chemical diagram, ranking their relative stability by a necessarily approximate estimate of the crystal energy. Such calculations are becoming feasible for molecules of a size and flexibility of small molecule pharmaceuticals. Contrasting the crystal energy landscape, the computer generated structures that are thermodynamically plausible as polymorphs, with the results of experimental polymorph screening, shows that CSP studies are not limited to being a search for the most thermodynamically stable crystal structure but can play a valuable role in understanding polymorphism and the potential complexity of crystallisation behaviour.[1] This presentation will illustrate the use of CSP as a complement to industrial-type solid form screening activities. Examples will include olanzapine, [2] tazofelone, two closely related 5-HT2a agonists and 6-[(5-chloro-2-([(4-chloro-2-fluorophenyl)methyl]oxy)phenyl)methyl]-2-pyridinecarboxylic acid (GSK269984B).[3] This illustrates the use of the crystal energy landscape to understand disorder, help structurally characterise metastable polymorphs and suggest whether there are additional polymorphs to be targeted. Since crystal energy landscapes usually include a wider range of crystal structures than known polymorphs, it raises the scientific question as to what determines which structures can be observed as metastable polymorphs. Thus both scientific as well as technological challenges need to be overcome before we can predict polymorphs.


2018 ◽  
Vol 140 (32) ◽  
pp. 10158-10168 ◽  
Author(s):  
Kevin Ryan ◽  
Jeff Lengyel ◽  
Michael Shatruk

RSC Advances ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 3577-3581 ◽  
Author(s):  
Nursultan Sagatov ◽  
Pavel N. Gavryushkin ◽  
Talgat M. Inerbaev ◽  
Konstantin D. Litasov

We carried out ab initio calculations on the crystal structure prediction and determination of P–T diagrams within the quasi-harmonic approximation for Fe7N3 and Fe7C3.


CrystEngComm ◽  
2021 ◽  
Author(s):  
Jianjun Hu ◽  
Wenhui Yang ◽  
Rongzhi Dong ◽  
Yuxin Li ◽  
Xiang Li ◽  
...  

Crystal structure prediction is now playing an increasingly important role in the discovery of new materials or crystal engineering.


Author(s):  
Suryakanti Debata ◽  
Smruti R. Sahoo ◽  
Rudranarayan Khatua ◽  
Sridhar Sahu

In this study, we present an effective molecular design strategy to develop the n-type charge transport characteristics in organic semiconductors, using ring-fused double perylene diimides (DPDIs) as the model compounds.


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