More Like this

1. Superstructural diversity in salt-cocrystals: higher-order hydrogen-bonded assemblies formed using U-shaped dications and with assistance of π − –π stacking

   https://doi.org/10.1039/D0CC02671A  

   Yelgaonkar, Shweta P. ; Kiani, Daniyal ; Baltrusaitis, Jonas ; MacGillivray, Leonard R. ( June 2020 , Chemical Communications)

   null (Ed.)

   Salt cocrystals with components that assemble by hydrogen bonds and aromatic anion–molecule stacks (π − –π stacks) are reported. U-shaped bipyridines and an isocoumarin carboxylic acid self-assemble to form 5-, 6-, and 10-component aggregates with components in double and quadruple face-to-face stacks. DFT calculations support the π − –π stacks to help stabilize the salt cocrystals. 

   more » « less
2. Co-operative halogen bonds and nonconventional sp -C—H...O hydrogen bonds in 1:1 cocrystals formed between diethynylpyridines and N -halosuccinimides

   https://doi.org/10.1107/S2053229622006635  

   Bosch, Eric ; Bowling, Nathan P. ( July 2022 , Acta Crystallographica Section C Structural Chemistry)

   The rapid evaporation of 1:1 solutions of diethynylpyridines and N -halosuccinimides, that react together to form haloalkynes, led to the isolation of unreacted 1:1 cocrystals of the two components. The 1:1 cocrystal formed between 2,6-diethynylpyridine and N -iodosuccinimide (C 4 H 4 INO 2 ·C 9 H 5 N) contains an N -iodosuccinimide–pyridine I...N halogen bond and two terminal alkyne–succinimide carbonyl C—H...O hydrogen bonds. The three-dimensional extended structure features interwoven double-stranded supramolecular polymers that are interconnected through halogen bonds. The cocrystal formed between 3,5-diethynylpyridine and N -iodosuccinimide (C 4 H 4 INO 2 ·C 9 H 5 N) also features an I...N halogen bond and two C—H...O hydrogen bonds. However, the components form essentially planar double-stranded one-dimensional zigzag supramolecular polymers. The cocrystal formed between 3,5-diethynylpyridine and N -bromosuccinimide (C 4 H 4 BrNO 2 ·C 9 H 5 N) is isomorphous to the cocrystal formed between 3,5-diethynylpyridine and N -iodosuccinimide, with a Br...N halogen bond instead of an I...N halogen bond. 

   more » « less
3. Symmetry and 1 H NMR chemical shifts of short hydrogen bonds: impact of electronic and nuclear quantum effects

   https://doi.org/10.1039/C9CP06840F  

   Zhou, Shengmin ; Wang, Lu ( March 2020 , Physical Chemistry Chemical Physics)

   Short hydrogen bonds (SHBs), which have donor and acceptor separations below 2.7 Å, occur extensively in small molecules and proteins. Due to their compact structures, SHBs exhibit prominent covalent characters with elongated Donor–H bonds and highly downfield (>14 ppm) 1 H NMR chemical shifts. In this work, we carry out first principles simulations on a set of model molecules to assess how quantum effects determine the symmetry and chemical shift of their SHBs. From simulations that incorporate the quantum mechanical nature of both the electrons and nuclei, we reveal a universal relation between the chemical shift and the position of the proton in a SHB, and unravel the origin of the observed downfield spectral signatures. We further develop a metric that allows one to accurately and efficiently determine the proton position directly from its 1 H chemical shift, which will facilitate the experimental examination of SHBs in both small molecules and biological macromolecules. 

   more » « less
4. Time-of-flight electron scattering from molecular hydrogen: Benchmark cross sections for excitation of the X1Σg+→b3Σu+ transition

   https://doi.org/10.1103/PhysRevA.97.050702  

   Zawadzki, M. ; Wright, R. ; Dolmat, G. ; Martin, M. F. ; Hargreaves, L. ; Fursa, D. V. ; Zammit, M. C. ; Scarlett, L. H. ; Tapley, J. K. ; Savage, J. S. ; et al ( May 2018 , Physical Review A)
5. Low-energy electron scattering from molecular hydrogen: Excitation of the X1Σg+ to b3Σu+ transition

   https://doi.org/10.1103/PhysRevA.98.062704  

   Zawadzki, M. ; Wright, R. ; Dolmat, G. ; Martin, M. F. ; Diaz, B. ; Hargreaves, L. ; Coleman, D. ; Fursa, D. V. ; Zammit, M. C. ; Scarlett, L. H. ; et al ( December 2018 , Physical Review A)