The fast atom bobardment mass spectra of phenolate-bridged N<sub>8</sub>O<sub>3</sub> Schiff-2base cryptands derived from tris （2-aminoethyl） amine （tren） with 2, 6-dlformyl-4-R-phenol （Cr...The fast atom bobardment mass spectra of phenolate-bridged N<sub>8</sub>O<sub>3</sub> Schiff-2base cryptands derived from tris （2-aminoethyl） amine （tren） with 2, 6-dlformyl-4-R-phenol （Cryptand H<sub>3</sub>L<sup>1</sup>, R=OMe） H<sub>3</sub>L<sup>3</sup>, Br, and H<sub>3</sub>L<sup>4</sup>, Ph) in the presence of NaOH or KON in methanol at ambient temperature was investigaed and compared with IR, UV-Vis, <sup>1</sup>H and <sup>13</sup>H NMR. The characteristic spectra of the cryptates posseessing different proton form cryptands were discussed.展开更多
The Schiff base cryptand and its cryptates were synthesized with the methods of [1+1] condensation of trialdehyde and tris(2-aminoethyl)amine and obtained in 60-65%, 5-25% and 70-80% yields respectively with or withou...The Schiff base cryptand and its cryptates were synthesized with the methods of [1+1] condensation of trialdehyde and tris(2-aminoethyl)amine and obtained in 60-65%, 5-25% and 70-80% yields respectively with or without some rare earth elements as templates. The polyoxa-aza cryptand was produced in 72% and 60-70% yields with reduction of Schiff base and its cryptates respectively.展开更多
The bicyclic cryptand 1,4,7, 10,13,16,21, 24-octaaza-bigcyclo [8, 8,8] hexacosan-3, 8, 12, 17, 20, 25-hex-one (COBH) bearing diaminoethane groups along the eight-atom bridges was synthesized. The structure consists of...The bicyclic cryptand 1,4,7, 10,13,16,21, 24-octaaza-bigcyclo [8, 8,8] hexacosan-3, 8, 12, 17, 20, 25-hex-one (COBH) bearing diaminoethane groups along the eight-atom bridges was synthesized. The structure consists of discrete neutral macrobicyclic units; the two cycles share the two tertiary amine nitrogen atoms, which exhibit an endo-cndo conformation. Three identical branches formed by 1, 2-diaminoethane link the two tertiary amine groups. The protonation reactions of cryptand (COBH) and its complex formation with copper (II) were investigated by potentiometry in water and in a DMSO/water (80:20 in mass ratio) mixture as solvents. The cryptand acts as a his-base through its two N-bridgehead and exhibits a strong cooperativity that favors the first protonation and makes the second one difficult (△pK= 5.0). An inward rotation of the amide groups to form hydrogen bonds accounts for this cooperativity. The interaction of COBH with copper (II) leads to several binuclear complex proton contents.展开更多
A new cryptand/paraquat [2]pseudorotaxane and its crown ether analog were synthesized and characterized by proton NMR, mass spectrometry, and single crystal X-ray analysis. The Job plots based on proton NMR data demon...A new cryptand/paraquat [2]pseudorotaxane and its crown ether analog were synthesized and characterized by proton NMR, mass spectrometry, and single crystal X-ray analysis. The Job plots based on proton NMR data demonstrated that both the complex between cryptand 1 and paraquat derivative 2a and the complex between bis(p-phenylene)-34-crown-10 (3) and paraquat derivative 2b have 1:1 stoichiometry in solution. The apparent association constants (Ka,exp) of 1·2a and 3·2b calculated for 1:1 complexes were 1.4 (±0.2) × 104 and 4.7 (± 0.5) × 102 M-1, respectively. X-ray analysis showed that 1·2a is stabilized by ten hydrogen bonds and face-to-face π-stacking interactions in the solid state, while 3·2b is stabilized by four hydrogen bonds and face-to-face π-stacking interactions. As well as in the X-ray structure of 1·2c, a water molecule acts as a hydrogen bridge between the β-pyridinium protons of 2a and the ether oxygen atoms of 1 in 1·2a. The successful preparation of 1·2a demonstrated that the tert-butyl group is not big enough to be a stopper for rotaxanes based on 1.展开更多
文摘The fast atom bobardment mass spectra of phenolate-bridged N<sub>8</sub>O<sub>3</sub> Schiff-2base cryptands derived from tris （2-aminoethyl） amine （tren） with 2, 6-dlformyl-4-R-phenol （Cryptand H<sub>3</sub>L<sup>1</sup>, R=OMe） H<sub>3</sub>L<sup>3</sup>, Br, and H<sub>3</sub>L<sup>4</sup>, Ph) in the presence of NaOH or KON in methanol at ambient temperature was investigaed and compared with IR, UV-Vis, <sup>1</sup>H and <sup>13</sup>H NMR. The characteristic spectra of the cryptates posseessing different proton form cryptands were discussed.
文摘The Schiff base cryptand and its cryptates were synthesized with the methods of [1+1] condensation of trialdehyde and tris(2-aminoethyl)amine and obtained in 60-65%, 5-25% and 70-80% yields respectively with or without some rare earth elements as templates. The polyoxa-aza cryptand was produced in 72% and 60-70% yields with reduction of Schiff base and its cryptates respectively.
基金the National Natural Science Foundation of China (No.29875018) and the Natural Science Foundation of Gansu Province (ZS991-A25-
文摘The bicyclic cryptand 1,4,7, 10,13,16,21, 24-octaaza-bigcyclo [8, 8,8] hexacosan-3, 8, 12, 17, 20, 25-hex-one (COBH) bearing diaminoethane groups along the eight-atom bridges was synthesized. The structure consists of discrete neutral macrobicyclic units; the two cycles share the two tertiary amine nitrogen atoms, which exhibit an endo-cndo conformation. Three identical branches formed by 1, 2-diaminoethane link the two tertiary amine groups. The protonation reactions of cryptand (COBH) and its complex formation with copper (II) were investigated by potentiometry in water and in a DMSO/water (80:20 in mass ratio) mixture as solvents. The cryptand acts as a his-base through its two N-bridgehead and exhibits a strong cooperativity that favors the first protonation and makes the second one difficult (△pK= 5.0). An inward rotation of the amide groups to form hydrogen bonds accounts for this cooperativity. The interaction of COBH with copper (II) leads to several binuclear complex proton contents.
基金supported by the National Science Foundation of USA (Grant No. DMR0097126)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20070335152)
文摘A new cryptand/paraquat [2]pseudorotaxane and its crown ether analog were synthesized and characterized by proton NMR, mass spectrometry, and single crystal X-ray analysis. The Job plots based on proton NMR data demonstrated that both the complex between cryptand 1 and paraquat derivative 2a and the complex between bis(p-phenylene)-34-crown-10 (3) and paraquat derivative 2b have 1:1 stoichiometry in solution. The apparent association constants (Ka,exp) of 1·2a and 3·2b calculated for 1:1 complexes were 1.4 (±0.2) × 104 and 4.7 (± 0.5) × 102 M-1, respectively. X-ray analysis showed that 1·2a is stabilized by ten hydrogen bonds and face-to-face π-stacking interactions in the solid state, while 3·2b is stabilized by four hydrogen bonds and face-to-face π-stacking interactions. As well as in the X-ray structure of 1·2c, a water molecule acts as a hydrogen bridge between the β-pyridinium protons of 2a and the ether oxygen atoms of 1 in 1·2a. The successful preparation of 1·2a demonstrated that the tert-butyl group is not big enough to be a stopper for rotaxanes based on 1.
