All Outputs (80)

Crystal size, shape, and conformational changes drive both the disappearance and reappearance of ritonavir polymorphs in the mill. (2024)
Journal Article
Sacchi, P., Wright, S. E., Neoptolemou, P., Lampronti, G. I., Rajagopalan, A. K., Kras, W., …Cruz-Cabeza, A. J. (2024). Crystal size, shape, and conformational changes drive both the disappearance and reappearance of ritonavir polymorphs in the mill. Proceedings of the National Academy of Sciences, 121(15), Article e2319127121. https://doi.org/10.1073/pnas.2319127121

Organic compounds can crystallize in different forms known as polymorphs. Discovery and control of polymorphism is crucial to the pharmaceutical industry since different polymorphs can have significantly different physical properties which impacts th... Read More about Crystal size, shape, and conformational changes drive both the disappearance and reappearance of ritonavir polymorphs in the mill..

Revisiting the Van Vleck second moment for characterizing molecular motion in organic solids (2023)
Journal Article
Sturniolo, S., Wickins, H. M., & Hodgkinson, P. (2023). Revisiting the Van Vleck second moment for characterizing molecular motion in organic solids. The Journal of Chemical Physics, 158(24), https://doi.org/10.1063/5.0151022

Van Vleck’s classic theory of the second moment of lineshapes in 1H nuclear magnetic resonance (NMR) is reworked in a form that allows the effect of rapid molecular motion on second moments to be calculated in a semi-analytical fashion. This is much... Read More about Revisiting the Van Vleck second moment for characterizing molecular motion in organic solids.

A new avenue to relaxor-like ferroelectric behaviour found by probing the structure and dynamics of [NH3NH2]Mg(HCO2)3 (2023)
Journal Article
Hitchings, T. J., Wickins, H. M., Peat, G. U. L., Hodgkinson, P., Srivastava, A. K., Lu, T., …Saines, P. J. (2023). A new avenue to relaxor-like ferroelectric behaviour found by probing the structure and dynamics of [NH3NH2]Mg(HCO2)3. Journal of Materials Chemistry C Materials for optical and electronic devices, 11(28), 9695-9706. https://doi.org/10.1039/d3tc00480e

The field of relaxor ferroelectrics has long been dominated by ceramic oxide materials exhibiting large polarisations with temperature and frequency dependence. Intriguingly, the dense metal–organic framework (MOF) [NH3NH2]Mg(HCO2)3 was reported as o... Read More about A new avenue to relaxor-like ferroelectric behaviour found by probing the structure and dynamics of [NH3NH2]Mg(HCO2)3.

Structured ternary fluids as nanocrystal incubators for enhanced crystallization control (2022)
Journal Article
Maunder, J., Aguilar, J., Hodgkinson, P., & Cooper, S. (2022). Structured ternary fluids as nanocrystal incubators for enhanced crystallization control. Chemical Science, 13(44), 13132-13140. https://doi.org/10.1039/d2sc04413g

In crystallization from solution, a ubiquitous process in both industry and the natural world, nucleation is usually the rate-determining step, followed by faster crystal growth. Consequently, crystals typically exist in the nm-size range for such li... Read More about Structured ternary fluids as nanocrystal incubators for enhanced crystallization control.

Resolving alternative structure determinations of indapamide using 13C solid-state NMR​ (2022)
Journal Article
Evans, C. L., Evans, I. R., & Hodgkinson, P. (2022). Resolving alternative structure determinations of indapamide using 13C solid-state NMR​. Chemical Communications, 58(30), 4767-4770. https://doi.org/10.1039/d1cc06256e

The conflict between alternative crystal structures in the Cambridge Structural Database for the diuretic drug indapamide hemihydrate (IND) has been resolved with the aid of 13C solid-state NMR. IND is seen to contain multiple distinct molecules in t... Read More about Resolving alternative structure determinations of indapamide using 13C solid-state NMR​.

Characterization of crystalline and amorphous forms of irbesartan by multi-nuclear solid-state NMR (2022)
Journal Article
Skotnicki, M., & Hodgkinson, P. (2022). Characterization of crystalline and amorphous forms of irbesartan by multi-nuclear solid-state NMR. Solid State Nuclear Magnetic Resonance, 118, https://doi.org/10.1016/j.ssnmr.2022.101783

Irbesartan (IRB) is an antihypertensive drug which exhibits the rare phenomenon of desmotropy; its 1H- and 2H- tetrazole tautomers can be isolated as distinct crystalline forms. The crystalline forms of IRB are poorly soluble, hence the amorphous for... Read More about Characterization of crystalline and amorphous forms of irbesartan by multi-nuclear solid-state NMR.

A study of the dynamics and structure of the dielectric anomaly within the molecular solid TEA(TCNQ)2 (2022)
Journal Article
Berlie, A., Terry, I., Szablewski, M., Telling, M., Apperley, D., Hodgkinson, P., & Zeller, D. (2022). A study of the dynamics and structure of the dielectric anomaly within the molecular solid TEA(TCNQ)2. Physical Chemistry Chemical Physics, 24(12), 7481-7492. https://doi.org/10.1039/d2cp00142j

With rising interest in organic-based functional materials, it is important to understand the nature of magnetic and electrical transitions within these types of systems. One intriguing material is triethylammonium bis-7,7,8,8-tetracyanoquinodimethan... Read More about A study of the dynamics and structure of the dielectric anomaly within the molecular solid TEA(TCNQ)2.

Paramagnetic solid-state NMR assignment and novel chemical conversion of the aldehyde group to dihydrogen ortho ester and hemiacetal moieties in copper(ii)- and cobalt(ii)-pyridinecarboxaldehyde complexes (2021)
Journal Article
Crespi, A. F., Sánchez, V. M., Vega, D., Pérez, A. L., Brondino, C. D., Linck, Y. G., …Lázaro-Martínez, J. M. (2021). Paramagnetic solid-state NMR assignment and novel chemical conversion of the aldehyde group to dihydrogen ortho ester and hemiacetal moieties in copper(ii)- and cobalt(ii)-pyridinecarboxaldehyde complexes. RSC Advances, 11(33), 20216-20231. https://doi.org/10.1039/d1ra02512k

The complex chemical functionalization of aldehyde moieties in Cu(II)- and Co(II)-pyridinecarboxaldehyde complexes was studied. X-ray studies demonstrated that the aldehyde group (RCHO) of the four pyridine molecules is converted to dihydrogen ortho... Read More about Paramagnetic solid-state NMR assignment and novel chemical conversion of the aldehyde group to dihydrogen ortho ester and hemiacetal moieties in copper(ii)- and cobalt(ii)-pyridinecarboxaldehyde complexes.

Towards accurate predictions of proton NMR parameters in molecular solids (2020)
Journal Article
Dracinsky, M., Vícha, J., Bártová, K., & Hodgkinson, P. (2020). Towards accurate predictions of proton NMR parameters in molecular solids. ChemPhysChem, 21(18), 2075-2083. https://doi.org/10.1002/cphc.202000629

The factors contributing to the accuracy of quantum‐chemical calculations of proton NMR chemical shifts in molecular solids are systematically investigated. Proton chemical shifts of six solid amino acids with hydrogen atoms in various bonding enviro... Read More about Towards accurate predictions of proton NMR parameters in molecular solids.

Synthesis and structural characterization of cocrystals of isoniazid and cinnamic acid derivatives (2020)
Journal Article
Mashhadi, S. M. A., Yufit, D., Liu, H., Hodgkinson, P., & Yunus, U. (2020). Synthesis and structural characterization of cocrystals of isoniazid and cinnamic acid derivatives. Journal of Molecular Structure, 1219, Article 128621. https://doi.org/10.1016/j.molstruc.2020.128621

Isoniazid is a key antitubercular agent which exhibits poor chemical stability in the solid state. Cocrystallization with hydroxyl derivatives of cinnamic acid, which themselves possesses antitubercular and antioxidant activity, may produce solid for... Read More about Synthesis and structural characterization of cocrystals of isoniazid and cinnamic acid derivatives.

NMR Crystallography of Molecular Organics (2020)
Journal Article
Hodgkinson, P. (2020). NMR Crystallography of Molecular Organics. Progress in Nuclear Magnetic Resonance Spectroscopy, 118-119, 10-53. https://doi.org/10.1016/j.pnmrs.2020.03.001

Developments of NMR methodology to characterise the structures of molecular organic structures are reviewed, concentrating on the previous decade of research in which density functional theory-based calculations of NMR parameters in periodic solids h... Read More about NMR Crystallography of Molecular Organics.

Resolving Alternative Organic Crystal Structures using Density Functional Theory and NMR Chemical Shifts (2020)
Journal Article
Widdifield, C., Farrell, J., Cole, J., Howard, J., & Hodgkinson, P. (2020). Resolving Alternative Organic Crystal Structures using Density Functional Theory and NMR Chemical Shifts. Chemical Science, 11(11), 2987-2992. https://doi.org/10.1039/c9sc04964a

Alternative (‘repeat’) determinations of organic crystal structures deposited in the Cambridge Structural Database are analysed to characterise the nature and magnitude of the differences between structure solutions obtained by diffraction methods. O... Read More about Resolving Alternative Organic Crystal Structures using Density Functional Theory and NMR Chemical Shifts.

Shape-Selective Crystallisation of Fluxional Carbon Cages (2018)
Journal Article
Bismillah, A., Sturala, J., Chapin, B., Yufit, D., Hodgkinson, P., & McGonigal, P. (2018). Shape-Selective Crystallisation of Fluxional Carbon Cages. Chemical Science, 9(46), 8631-8636. https://doi.org/10.1039/c8sc04303e

Dynamic covalent rearrangements of fluxional carbon cages, such as bullvalenes and barbaralanes, impart ‘shapeshifting’ molecular properties. Here, a series of five barbaralanes each interconvert dynamically between two constitutional isomers in solu... Read More about Shape-Selective Crystallisation of Fluxional Carbon Cages.

Perspective: Current advances in solid-state NMR spectroscopy (2018)
Journal Article
Ashbrook, S. E., & Hodgkinson, P. (2018). Perspective: Current advances in solid-state NMR spectroscopy. The Journal of Chemical Physics, 149(4), Article 040901. https://doi.org/10.1063/1.5038547

In contrast to the rapid and revolutionary impact of solution-state Nuclear Magnetic Resonance (NMR) on modern chemistry, the field of solid-state NMR has matured more slowly. This reflects the major technical challenges of much reduced spectral reso... Read More about Perspective: Current advances in solid-state NMR spectroscopy.

Proton transfer in guanine–cytosine base pair analogues studied by NMR spectroscopy and PIMD simulations (2018)
Journal Article
Pohl, R., Socha, O., Slavíček, P., Šála, M., Hodgkinson, P., & Dračínský, M. (2018). Proton transfer in guanine–cytosine base pair analogues studied by NMR spectroscopy and PIMD simulations. Faraday Discussions, 212, 331-344. https://doi.org/10.1039/c8fd00070k

It has been hypothesised that proton tunnelling between paired nucleobases significantly enhances the formation of rare tautomeric forms and hence leads to errors in DNA replication. Here, we study nuclear quantum effects (NQEs) using deuterium isoto... Read More about Proton transfer in guanine–cytosine base pair analogues studied by NMR spectroscopy and PIMD simulations.

Improving Confidence in Crystal Structure Solutions Using NMR Crystallography: The Case of β-Piroxicam (2018)
Journal Article
Tatton, A. S., Blade, H., Brown, S. P., Hodgkinson, P., Hughes, L. P., Lill, S. O. N., & Yates, J. R. (2018). Improving Confidence in Crystal Structure Solutions Using NMR Crystallography: The Case of β-Piroxicam. Crystal Growth and Design, 18(6), 3339-3351. https://doi.org/10.1021/acs.cgd.8b00022

NMR crystallographic techniques are used to validate a structure of β-piroxicam determined from powder X-ray diffraction (PXRD) with a relatively poor R-factor. Geometry optimization of PXRD- and single-crystal XRD- derived structures results in conv... Read More about Improving Confidence in Crystal Structure Solutions Using NMR Crystallography: The Case of β-Piroxicam.

Exploring Systematic Discrepancies in DFT Calculations of Chlorine Nuclear Quadrupole Couplings (2017)
Journal Article
Socha, O., Hodgkinson, P., Widdifield, C. M., Yates, J. R., & Dračínský, M. (2017). Exploring Systematic Discrepancies in DFT Calculations of Chlorine Nuclear Quadrupole Couplings. The Journal of Physical Chemistry A, 121(21), 4103-4113. https://doi.org/10.1021/acs.jpca.7b02810

Previous studies have revealed significant discrepancies between density functional theory (DFT)-calculated and experimental nuclear quadrupolar coupling constants (CQ) for chlorine atoms, particularly in ionic solids. Various aspects of the computat... Read More about Exploring Systematic Discrepancies in DFT Calculations of Chlorine Nuclear Quadrupole Couplings.

Structure and Physicochemical Characterization of a Naproxen-Picolinamide Cocrystal (2017)
Journal Article
Kerr, H., Softley, L., Suresh, K., Hodgkinson, P., & Evans, I. (2017). Structure and Physicochemical Characterization of a Naproxen-Picolinamide Cocrystal. Acta Crystallographica Section C: Structural Chemistry, C73(3), https://doi.org/10.1107/s2053229616011980

Naproxen (NPX) is a nonsteroidal anti-inflammatory drug with pain- and fever-relieving properties, currently marketed in the sodium salt form to overcome solubility problems; however, alternative solutions for improving its solubility across all pH v... Read More about Structure and Physicochemical Characterization of a Naproxen-Picolinamide Cocrystal.

Rationalising heteronuclear decoupling in refocussing applications of solid-state NMR (2017)
Journal Article
Frantsuzov, I., Vasa, S. K., Ernst, M. E., Brown, S. P., Zorin, V., Kentgens, A. P., & Hodgkinson, P. (2017). Rationalising heteronuclear decoupling in refocussing applications of solid-state NMR. ChemPhysChem, 18(4), 394-405. https://doi.org/10.1002/cphc.201601003

Factors affecting the performance of 1H heteronuclear decoupling sequences for magic-angle spinning (MAS) NMR spectroscopy of organic solids are explored, as observed by time constants for the decay of nuclear magnetisation under a spin-echo (math fo... Read More about Rationalising heteronuclear decoupling in refocussing applications of solid-state NMR.

Testing the limits of NMR crystallography: the case of caffeine-citric acid hydrate (2016)
Journal Article
Kerr, H. E., Mason, H. E., Sparkes, H. A., & Hodgkinson, P. (2016). Testing the limits of NMR crystallography: the case of caffeine-citric acid hydrate. CrystEngComm, 18(35), 6700-6707. https://doi.org/10.1039/c6ce01453d

The crystal structure of a new 1 : 2 caffeine–citric acid hydrate cocrystal is presented. The caffeine molecules are disordered over two positions, with the nature of the disorder confirmed to be static by 13C solid-state NMR. NMR linewidths in stati... Read More about Testing the limits of NMR crystallography: the case of caffeine-citric acid hydrate.