The significance of the heteroatom in influencing the acidity and binding affinity of the C(2)-H donor in five-membered heterocyclic rings is explored. The water clusters of benzoxazole (BOX) are studied in a supersonic jet by IR-UV double resonance spectroscopy and compared with those of benzimidazole (BIM) and its N-methyl derivative (MBIM). Two conformers are identified for the monohydrated cluster, both of which are O-H···N bound and differ in their orientation with respect to the intermolecular hydrogen bond. IR spectroscopy of the doubly hydrated cluster shows the presence of an intensity enhanced C(2)-H (carbon atom between the heteroatoms in the five-membered ring) stretching mode in addition to two red-shifted bound OH stretches, indicating that the water molecules form a hydrogen-bonded bridge encompassing the N acceptor and the weakly activated C(2)-H bond in oxazole. Comparison of the topological parameters of electron density, natural bond orbital analyses, and computed binding energies of the analogous hydrated structures of BOX, BIM, and MBIM indicates that the C(2)-H bond in the former is a more potent H-bond donor.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/acs.jpca.7b04058 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Direct C2-H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes.
Beilstein J Org Chem
April 2023
Department of Chemical and Pharmaceutical Sciences, INSTM UdR Trieste, University of Trieste, via Licio Giorgieri 1, 34127 Trieste, Italy.
A light-driven metal-free protocol for the synthesis of sulfone-containing indoles under mild conditions is reported. Specifically, the process is driven by the photochemical activity of halogen-bonded complexes formed upon complexation of a sacrificial donor, namely 1,4-diazabicyclo[2.2.
View Article and Find Full Text PDF1,2-Hydrogenation and Transhydrogenation Catalyzed by 3-Ketosteroid Δ-Dehydrogenase from -Kinetics, Isotope Labelling and QM:MM Modelling Studies.
Int J Mol Sci
November 2022
Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Krakow, Poland.
Bacteria and fungi that are able to metabolize steroids express 3-ketosteroid-Δ-dehydrogenases (KstDs). KstDs such as AcmB form Chol-1 catalyze the enantioselective 1α,2β-dehydrogenation of steroids to their desaturated analogues, e.g.
View Article and Find Full Text PDFClade II nitrous oxide respiration of Wolinella succinogenes depends on the NosG, -C1, -C2, -H electron transport module, NosB and a Rieske/cytochrome bc complex.
Environ Microbiol
December 2017
Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany.
Microbial reduction of nitrous oxide (N O) is an environmentally significant process in the biogeochemical nitrogen cycle. However, it has been recognized only recently that the gene encoding N O reductase (nosZ) is organized in varying genetic contexts, thereby defining clade I (or 'typical') and clade II (or 'atypical') N O reductases and nos gene clusters. This study addresses the enzymology of the clade II Nos system from Wolinella succinogenes, a nitrate-ammonifying and N O-respiring Epsilonproteobacterium that contains a cytochrome c N O reductase (cNosZ).
View Article and Find Full Text PDFCα-H carries information of a hydrogen bond involving the geminal hydroxyl group: a case study with a hydrogen-bonded complex of 1,1,1,3,3,3-hexafluoro-2-propanol and tertiary amines.
J Phys Chem A
February 2014
Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata 700032, India.
Experimental measurement of the contribution of H-bonding to intermolecular and intramolecular interactions that provide specificity to biological complex formation is an important aspect of macromolecular chemistry and structural biology. However, there are very few viable methods available to determine the energetic contribution of an individual hydrogen bond to binding and catalysis in biological systems. Therefore, the methods that use secondary deuterium isotope effects analyzed by NMR or equilibrium or kinetic isotope effect measurements are attractive ways to gain information on the H-bonding properties of an alcohol system, particularly in a biological environment.
View Article and Find Full Text PDFA new Raman spectroscopic probe of both the protonation state and noncovalent interactions of histidine residues.
J Phys Chem A
July 2013
Department of Chemistry, Haverford College, 370 Lancaster Avenue, Haverford, Pennsylvania 19041-1392, USA.
The amino acid histidine (His) has a number of unique roles that can dictate function in proteins, and these roles are typically conferred through noncovalent interactions that depend on the protonation state of His's 4-substituted imidazole ring. His's protonation state can vary near physiological pH, and a probe of His's variable protonation state and its resulting noncovalent interactions that has both high time resolution and no sample limitations could find wide use in determining the role of particular His residues in proteins. Here we use a classic deuterium exchange reaction to replace the C2-H hydrogen atom of the His imidazole ring with deuterium, leading to a unique aromatic C2-D stretching vibration whose frequency is sensitive to environmental changes across the entire imidazole ring.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!