More Like this

1. Palmitvaccenic Acid (Δ11- cis -hexadecenoic acid) Is Synthesized by an OLE1-like Desaturase in the Arbuscular Mycorrhiza Fungus Rhizophagus irregularis

   https://doi.org/10.1021/acs.biochem.0c00051  

   Brands, Mathias; Cahoon, Edgar B.; Dörmann, Peter (March 2020, Biochemistry)
2. Photoisomerization dynamics of trans – trans , cis – trans, and cis – cis diphenylbutadiene from broadband transient absorption spectroscopy and calculations

   https://doi.org/10.1063/5.0007241  

   Krohn, O. A.; Quick, M.; Sudarkova, S. M.; Ioffe, I. N.; Richter, C.; Kovalenko, S. A. (June 2020, The Journal of Chemical Physics)
3. Relative hydrophilicities of cis and trans formamides

   https://doi.org/10.1073/pnas.1911331116  

   Li, Yong-Sheng; Escobar, Luis; Zhu, Yu-Jie; Cohen, Yoram; Ballester, Pablo; Rebek, Julius; Yu, Yang (October 2019, Proceedings of the National Academy of Sciences)

   Secondary formamides are widely encountered in biology and exist as mixtures of both cis and trans isomers. Here, we assess hydrophilicity differences between isomeric formamides through direct competition experiments. Formamides bearing long aliphatic chains were sequestered in a water-soluble molecular container having a hydrophobic cavity with an end open to the aqueous medium. NMR spectroscopic experiments reveal a modest preference (<1 kcal/mol) for aqueous solvation of the trans formamide terminals over the cis isomers. With diformamides, the supramolecular approach allows staging of intramolecular competition between short-lived species with subtle differences in hydrophobic properties. 

   more » « less
4. Formation and detection of metastable formic acid in a supersonic expansion: High resolution infrared spectroscopy of the jet-cooled cis -HCOOH conformer

   https://doi.org/10.1063/5.0093401  

   Doney, Kirstin D.; Kortyna, Andrew; Chan, Ya-Chu; Nesbitt, David J. (May 2022, The Journal of Chemical Physics)

   High-resolution direct absorption infrared spectra of metastable cis-formic acid (HCOOH) trapped in a cis-well resonance behind a 15 kcal/mol barrier are reported for the first time, with the energetically unstable conformer produced in a supersonic slit plasma expansion of trans-formic acid/H 2 mixtures. We present a detailed high-resolution rovibrational analysis for cis-formic acid species in the OH stretch ( ν 1 ) fundamental, providing first precision vibrational band origin, rotational constants, and term values, which in conjunction with ab initio calculations at the couple-cluster with single, double, and perturbative triple [CCSD(T)]/ANOn (n = 0, 1, 2) level support the experimental assignments and establish critical points on the potential energy surface for internal rotor trans-to-cis isomerization. Relative intensities for a- and b-type transitions observed in the spectra permit the transition dipole moment components to be determined in the body fixed frame and prove to be in good agreement with ab initio CCSD(T) theoretical estimates but in poor agreement with simple bond-dipole predictions. The observed signal dependence on H 2 in the discharge suggests the presence of a novel H atom radical chemical mechanism for strongly endothermic “up-hill” internal rotor isomerization between trans- and cis-formic acid conformers. 

   more » « less
5. Electronic Spectroscopy of cis - and trans - meta -Vinylbenzyl Radicals

   https://doi.org/10.1021/acs.jpca.1c04496  

   Ross, Sederra D.; Flores, Jonathan; Hewett, Daniel M.; Reilly, Neil J. (July 2021, The Journal of Physical Chemistry A)