A Fluorine-Containing Cryptand for the Complexation of Anions and the Utility of <sup>19</sup>F NMR Spectroscopy for the Determination of Host-Guest Association

Plenio, Herbert; Diodone, Ralph

doi:10.1515/znb-1995-0716

Cited by 18 publications

(28 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Melting points were determined with a Meltemp melting point apparatus in sealed capillaries. Starting materials were available commercially or prepared according to literature procedures: 1,3-dimethyl-2-fluorobenzene, 1,3-bis(bromomethyl)-2-fluorobenzene, HO 5 , diaza-18-crown-6, aza-12-crown-4, aza-15-crown-5 and aza-18-crown-6, triflate salts, and picrate salts . Picrate extraction experiments were carried out according to a procedure by Cram et al and were performed under the same conditions used to reproduce the literature values for dicyclohexano-18-crown-6 …”

Section: Methodsmentioning

confidence: 99%

Covalently Bonded Fluorine as a σ-Donor for Groups I and II Metal Ions in Partially Fluorinated Macrocycles

Plenio

Diodone

1996

J. Am. Chem. Soc.

Self Cite

View full text Add to dashboard Cite

Novel fluoro cryptands and fluoro crown ethers were synthesized in good yields in the reactions of 1,3bis(bromomethyl)-2-fluorobenzene with diaza-18-crown-6 [the resulting two macrocycles are abbreviated as FN 2 O 4 (1 + 1 product) and (FN 2 O 4 ) 2 (2 + 2 product)], diaza-15-crown-5 [product abbreviated as FN 2 O 3 ], aza-(3n)-crown-(n) (n ) 4, 5, 6) [F(NO 3 ) 2 , F(NO 4 ) 2 , F(NO 5 ) 2 ], and the potassium salts of tetraethyleneglycol [FO 5 ] or pentaethylene glycol [FO 6 ] and in the reaction of 1-(bromomethyl)-3-methyl-2-fluorobenzene with aza-15-crown-5 [FNO 4 ]. The analogous reactions of 1,3-bis(bromomethyl)benzene with diaza-18-crown-6 [HN 2 O 4 ], diaza-15-crown-5 [HN 2 O 3 ], and the potassium salt of tetraethylene glycol [HO 5 ] led to the isolation of closely related fluorine-free cryptands and crown ethers. The 19 F NMR resonances of the fluoro macrocycles shift upon complexation of metal ions by between ∆δ ) -18.2 ppm and ∆δ ) +8.5 ppm relative to those of the respective free ligands. To explain the unexpected high-field shifts ∆δ of most metal complexes, a qualitative model is proposed which considers conformative rearrangements of the oxyethylene chain to be mainly responsible for the ∆δ values, with the deshielding effect of the positive charge of the metal ions being smaller in most cases. It was demonstrated that the 1 J CF coupling constants can be used to gauge the strength of metal-fluorine interactions since the values for 1 J CF range from 253 Hz (FN 2 O 4 ) to 238.5 Hz (Li + ‚FN 2 O 4 ), 242 Hz (Na + ‚FN 2 O 4 ), 246.5 Hz (K + ‚FN 2 O 4 ), and 249 Hz (Rb + ‚FN 2 O 4 ). The larger the metal ion the less it is able to migrate into the cavity and contact the C-F unit. The stability constants of the metal complexes of the fluoro macrocycles and their fluorine free relatives were determined by picrate extraction experiments and NMR competition experiments. It is evident from both investigations that the fluorine-containing macrocycles form more stable metal complexes than the analogous fluorine free systems. This is taken as a proof for C-F to metal ion σ-donor bonds. It is significant that this stabilizing effect is only observed when the radii of the metal ion and macrocyclic cavity are complementary, since only then can the metal ion contact the C-F unit. The crystal structures of FN 2 O 3 and the metal complexes were determined. In the solid state structures of all metal complexes with the exception of Na + ‚FNO 4 , short metalfluorine distances are observed, which are approximately as long as the respective metal-oxygen distances and much shorter than the metal-N distances [Li + ‚FN 2 O 3 : Li + illustrates the importance of fluorine coordination since this interaction is required to position the metal ion within the center of the cavity, whereas in Li + ‚HN 2 O 3 the cation is located on the outer edge of the cavity, completing its coordination sphere with one additional molecule of water.

show abstract

Section: Methodsmentioning

confidence: 99%

Covalently Bonded Fluorine as a σ-Donor for Groups I and II Metal Ions in Partially Fluorinated Macrocycles

Plenio

Diodone

1996

J. Am. Chem. Soc.

Self Cite

View full text Add to dashboard Cite

show abstract

“…A well-documented recipe for preparing azacyclophanes calls for macrocyclization by imine formation followed by reduction. ,− Strong but size-dependent complexation of oxoanions is observed with monocyclic − as well as with bicyclic members such as 38a 201 of this class. Efficient binding of nucleotides reaching log K assn of 4−5 202 is found in dilute acid and probably is of the inclusion type, as suggested by a number of crystal structures. , …”

Section: Positively Charged Anion Hostsmentioning

confidence: 99%

Artificial Organic Host Molecules for Anions

1997

View full text Add to dashboard Cite

“…London and Gabel [146] reported fluorobenzene boronic acid, which interacted with specific sugars. Plenio and Diodone [147] reported fluorine containing cryptands, which interact with perchlorate. These investigators have also reported a series of fluorocyclophanes and fluoro crown ethers to explore specific cation binding (e.g., K + , Li + , Na + , Ba 2+ , Sr 2+ , Ca 2+, and associated chemical shifts [136,148].…”

Section: Other Biological Relevant Ligandsmentioning

confidence: 99%

19F: A Versatile Reporter for Non-Invasive Physiology and Pharmacology Using Magnetic Resonance

Jian¹,

Kodibagkar²,

Cui³

et al. 2005

CMC

229

185

View full text Add to dashboard Cite

The fluorine atom provides an exciting tool for diverse spectroscopic and imaging applications using Magnetic Resonance. The organic chemistry of fluorine is widely established and it can provide a stable moiety for interrogating many aspects of physiology and pharmacology in vivo. Strong NMR signal, minimal background signal and exquisite sensitivity to changes in the microenvironment have been exploited to design and apply diverse reporter molecules. Classes of agents are presented to investigate gene activity, pH, metal ion concentrations (e.g., Ca(2+), Mg(2+), Na(+)), oxygen tension, hypoxia, vascular flow and vascular volume. In addition to interrogating speciality reporter molecules, (19)F NMR may be used to trace the fate of fluorinated drugs, such as chemotherapeutics (e.g., 5-fluorouracil, gemcitabine), anesthetics (e.g., isoflurane, methoxyflurane) and neuroleptics. NMR can provide useful information through multiple parameters, including chemical shift, scalar coupling, chemical exchange and relaxation processes (R1 and R2). Indeed, the large chemical shift range (approximately 300 ppm) can allow multiple agents to be examined, simultaneously, using NMR spectroscopy or chemical shift selective imaging.

show abstract

A Fluorine-Containing Cryptand for the Complexation of Anions and the Utility of ¹⁹F NMR Spectroscopy for the Determination of Host-Guest Association

Cited by 18 publications

References 9 publications

Covalently Bonded Fluorine as a σ-Donor for Groups I and II Metal Ions in Partially Fluorinated Macrocycles

Covalently Bonded Fluorine as a σ-Donor for Groups I and II Metal Ions in Partially Fluorinated Macrocycles

Artificial Organic Host Molecules for Anions

19F: A Versatile Reporter for Non-Invasive Physiology and Pharmacology Using Magnetic Resonance

Contact Info

Product

Resources

About

A Fluorine-Containing Cryptand for the Complexation of Anions and the Utility of 19F NMR Spectroscopy for the Determination of Host-Guest Association

Cited by 18 publications

References 9 publications

Covalently Bonded Fluorine as a σ-Donor for Groups I and II Metal Ions in Partially Fluorinated Macrocycles

Covalently Bonded Fluorine as a σ-Donor for Groups I and II Metal Ions in Partially Fluorinated Macrocycles

Artificial Organic Host Molecules for Anions

19F: A Versatile Reporter for Non-Invasive Physiology and Pharmacology Using Magnetic Resonance

Contact Info

Product

Resources

About

A Fluorine-Containing Cryptand for the Complexation of Anions and the Utility of ¹⁹F NMR Spectroscopy for the Determination of Host-Guest Association