Retention of strong intramolecular hydrogen bonds in high polarity solvents in binaphthalene–benzamide derivatives: extensive NMR studies

Abstract

NMR studies reveal very strong hydrogen bond unbreakable even in high polarity solvents.

Analysis of Ion Pairing in Solid State and Solution in p-Cymene Ruthenium Complexes

“…In complexes [1]Cl, [1]OTf, and [1]BF 4 , a relatively strong N−H•••X (X = Cl, O, F) hydrogen bonding interaction 71 was found in the three complexes, whereas those involving the adjacent H 3 ′ proton (in [1]Cl) or the H a ′ proton (in [1]OTf and [1]BF 4 ) were quite weak (Figure 4 and Table S6).…”

New Iron Twist to Chloroquine─Upgrading Antimalarials with Immunomodulatory and Antimicrobial Features

“…However, the same aryl derivates ( p -chlorophenyl analogues of 5a and 5b ) we prepared displayed Ar-NH as broad triplets ( 3 J = 4.0 Hz) as well. Moreover, this 3 J coupling was observed in the 1 H NMR spectrum (CDCl 3 , 400 MHz) of CQ (Ar-NH gave a doublet at 5.20 ppm with 3 J of 7.4 Hz), while in the CQ analogues with differing linear alkyl linkers (2–6 C-atoms) connecting the two nitrogens, the Ar-NH signal was assigned either as a bs or bt (without giving the 3 J value) . One of the reasons for the mentioned change in the Ar-NH signal multiplicity (and position) could be partial protonation during chromatography on SiO 2 or the use of non-deacidified CDCl 3 (see the Supporting Information).…”

Competing HB acceptors: an extensive NMR investigations corroborated by single crystal XRD and DFT calculations

“…However, in many earlier reports, this coupling completely vanished 45,46,48,49 in DMSO except in molecules where the structural restraint resists the complete breaking of HB by DMSO. 26,44 The retention of the 1h J FH for molecule 2 in the DMSO-d 6 is due to the favorable cis geometry (Fig. 1), which prevents the complete solvation of HB.…”

“…The detection of the signicantly large coupling strength between 19 F and 1 H has been attributed to be HB mediated. [26][27][28] There are several examples of detection of direct through space couplings between many homo-and hetero-nuclear spins, such as J HF , J FF J PF , and J PP , and between many other NMR active nuclei, and many reports have discussed the mechanism and strengths of such through-space interactions. 29 The detection of J FH has also been extensively debated as, whether it arises because of hydrogen bond or due to the overlap of electronic clouds.…”