TY - JOUR
T1 - Complexes of benzo-15-crown-5 with protonated primary amines and diamines
AU - Kryatova, Olga P.
AU - Korendovych, Ivan V.
AU - Rybak-Akimova, Elena V.
N1 - Funding Information:
ERA thanks Tufts University (Faculty Research Award) and the NSF for financial support. The CCD based X-ray diffractometer at Tufts University was purchased through Air Force DURIP Grant F49620-01-1-0242. The NMR facility in the Chemistry Department at Tufts University is supported by NSF grant CHE-9723772. The authors are grateful to Dr. Sergey Kryatov, Tufts University, and Professor Rebecca Roesner, Illinois Wesleyan University, for helpful discussions.
PY - 2004/5/17
Y1 - 2004/5/17
N2 - Three complexes of benzo-15-crown-5 (B15C5) with protonated primary amines [PhCH2NH3(B15C5)](ClO4), [p-C6H 4(CH2NH3)2(B15C5) 2](ClO4)2, and [(CH2) 4(NH3)2(B15C5)2](SCN)2 were isolated and studied in acetonitrile solutions by NMR, and in the solid state by X-ray crystallography. In all complexes, one B15C5 molecule was bound with each R-NH3+ moiety with characteristic small separation of 1.84-1.86Å between the nitrogen of the R-NH3 + group and the O5 mean plane of the crown residue. No sandwich-type complexes with a 1:2 R-NH3+/B15C5 stoichiometry were observed. Binding affinities of B15C5 in acetonitrile were similar for all ammonium cations studied: K1=550±10 M -1 for [PhCH2NH3]+; K 1=1100±100 and K2=400±30 M-1 for [p-C6H4(CH2NH3)2] 2+; and K1=1100±100 and K2=300±30 M-1 for [H3N(CH2)4NH 3]2+. The complexation is primarily enthalpy-driven (ΔH°=-4.9±0.5kcal/mol, ΔS°=-3.8±1.0eu for PhCH2NH3+-B15C5), as determined by variable temperature 1H NMR titrations.
AB - Three complexes of benzo-15-crown-5 (B15C5) with protonated primary amines [PhCH2NH3(B15C5)](ClO4), [p-C6H 4(CH2NH3)2(B15C5) 2](ClO4)2, and [(CH2) 4(NH3)2(B15C5)2](SCN)2 were isolated and studied in acetonitrile solutions by NMR, and in the solid state by X-ray crystallography. In all complexes, one B15C5 molecule was bound with each R-NH3+ moiety with characteristic small separation of 1.84-1.86Å between the nitrogen of the R-NH3 + group and the O5 mean plane of the crown residue. No sandwich-type complexes with a 1:2 R-NH3+/B15C5 stoichiometry were observed. Binding affinities of B15C5 in acetonitrile were similar for all ammonium cations studied: K1=550±10 M -1 for [PhCH2NH3]+; K 1=1100±100 and K2=400±30 M-1 for [p-C6H4(CH2NH3)2] 2+; and K1=1100±100 and K2=300±30 M-1 for [H3N(CH2)4NH 3]2+. The complexation is primarily enthalpy-driven (ΔH°=-4.9±0.5kcal/mol, ΔS°=-3.8±1.0eu for PhCH2NH3+-B15C5), as determined by variable temperature 1H NMR titrations.
KW - Alkylammonium
KW - Crown ethers
KW - Host-guest complexes
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U2 - 10.1016/j.tet.2004.03.080
DO - 10.1016/j.tet.2004.03.080
M3 - Article
AN - SCOPUS:2142694327
VL - 60
SP - 4579
EP - 4588
JO - Tetrahedron
JF - Tetrahedron
SN - 0040-4020
IS - 21
ER -