NMR studies of anion-induced conformational changes in diindolylureas and diindolylthioureas

Makuc, Damjan; Hiscock, Jennifer R.; Light, Mark E.; Gale, Philip A.; Plavec, Janez

doi:10.3762/bjoc.7.140

Cited by 25 publications

(13 citation statements)

References 40 publications

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“…A similar hydrogen‐bond interaction has been observed in reference 18 for the acetate and benzoate anions, where it was demonstrated that receptor 30 has three possible conformations (i.e., syn – syn , syn – anti and anti – anti ). In the absence of anion, the receptor is in the anti – anti conformation and in the presence of an anionic guest the complex adopts the syn – syn conformation.…”

Section: Resultssupporting

confidence: 82%

Towards the Discrimination of Carboxylates by Hydrogen‐Bond Donor Anion Receptors

Kadam

Martin

Haav

et al. 2015

Chemistry A European J

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The binding constants (log Kass ) of small synthetic receptor molecules based on indolocarbazole, carbazole, indole, urea and some others, as well as their combinations were measured for small carboxylate anions of different basicity, hydrophilicity and steric demands, that is, trimethylacetate, acetate, benzoate and lactate, in 0.5 % H2 O/[D6 ]DMSO by using the relative NMR-based measurement method. As a result, four separate binding affinity scales (ladders) including thirty-eight receptors were obtained with the scales anchored to indolocarbazole. The results indicate that the binding strength is largely, but not fully, determined by the strength of the primary hydrogen-bonding interaction. The latter in turn is largely determined by the basicity of the anion. The higher is the basicity of the anion the stronger in general is the binding, leading to the approximate order of increasing binding strength, lactate

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Section: Resultssupporting

confidence: 82%

Towards the Discrimination of Carboxylates by Hydrogen‐Bond Donor Anion Receptors

Kadam

Martin

Haav

et al. 2015

Chemistry A European J

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“…Because changes of 1 H NMR chemical shifts upon complexation of urea, thiourea, DIU , and DIT (but not sulfamide) with anions have been observed, NMR chemical shift calculations were performed for the free and complexed DIS (Table ). As expected, the chemical shifts for H 1 and H 8α/β were the most affected by the presence of an anion, with increased values relative to TMS when compared with the anion‐free DIS , in either the gas phase or implicit DMSO.…”

Section: Resultsmentioning

confidence: 99%

“…Some promising examples are diindolylureas ( DIU ) and diindolylthioureas ( DIT ), which have 4 N–H groups and high affinity to halides and oxoanions . These anions participate in the molecular recognition of DIU and DIT , inducing the conformational shift in DMSO solution towards a high‐energy conformation in an anion‐free environment …”

Section: Introductionmentioning

confidence: 99%

Anion effect on the conformational equilibrium of sulfamide and its N,N′‐diindolyl derivative: Insights on anion transportation

Mendonça

Fernandes

Cormanich

et al. 2018

J of Physical Organic Chem

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The relatively high acidity of the sulfamide hydrogens suggests a potential for the development of sulfamide derivatives as novel anion receptors. The interactions of sulfamide with F − , Cl − , CH 3 COO − , and H 2 PO 4 − anions were spectroscopically ( 1 H and 19 F NMR) and theoretically (density functional theory)analyzed, and the complexation through hydrogen bonds was confirmed by changes in the NMR signals and theoretical calculations. The replacement of 2 sulfamide hydrogens with indolyl groups yields the N,N′-diindolylsulfamide, whose bond rotations allow the interaction of 4 H(N) atoms with anions. The conformational preferences of DIS change upon the presence of anions, but they are practically insensitive to the anion type. According to the quantum theory of atoms in molecules, natural bond orbital analysis, and NMR chemical shifts, as well as to a thermodynamic cycle, the complex with fluoride is the most stable, followed by the oxoanion-derived models.

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“…Table provides a summary of the diagnostic 1 H NMR, 13 C NMR, and 15 N NMR chemical shifts, whereas the complete NMR data is reported in the Experimental Section. The 1 H NMR and 1 H, 15 N HSQC spectra of 1 – 4 are provided in Figures S5–S8 and S9–S12, respectively . The 1 H, 15 N HMBC spectrum of 4 is also included (Figure S13).…”

Section: Resultsmentioning

confidence: 99%

Colorimetric Naphthalene‐Based Thiosemicarbazide Anion Chemosensors with an Internal Charge Transfer Mechanism

et al. 2016

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A series of thiosemicarbazide anion chemosensors substituted with naphthalene and 4‐nitrophenyl or phenyl units were synthesized. The molecules were characterized by using 1H,13C DEPT and 15N NMR spectroscopy. The anion binding properties of compounds 1–4 were investigated by UV/Vis absorption and fluorescence spectroscopy in DMSO, DMSO/H2O (9:1 v/v), and acetonitrile with hydroxide, fluoride, acetate, hypophosphate, and chloride anions. Striking color changes were observed with nitro‐containing chemosensors 2–4 with all anions, with the exception of chloride, which was attributed to an internal charge‐transfer mechanism. 1H/13C/15N NMR titration studies and DFT and charge distribution calculations support a mechanism involving deprotonation of the central N–H bond. Compound 4 with a methylene spacer between the naphthalene and thiosemicarbazide moieties was deliberately designed as a fluorescent photoinduced electron‐transfer anion (PET) sensor. However, the methylene spacer did not prevent delocalization of the HOMO orbital between the planar aromatic ring and the thiosemicarbazide unit as expected on the basis of the “fluorophore–spacer–receptor” PET model.

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NMR studies of anion-induced conformational changes in diindolylureas and diindolylthioureas

Cited by 25 publications

References 40 publications

Towards the Discrimination of Carboxylates by Hydrogen‐Bond Donor Anion Receptors

Towards the Discrimination of Carboxylates by Hydrogen‐Bond Donor Anion Receptors

Anion effect on the conformational equilibrium of sulfamide and its N,N′‐diindolyl derivative: Insights on anion transportation

Colorimetric Naphthalene‐Based Thiosemicarbazide Anion Chemosensors with an Internal Charge Transfer Mechanism

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