title: Stability of porphyrin-calix[4]arene complexes analyzed by electrospray ionization mass spectrometry.
abstract: The stability of some porphyrin-calix[4]arene sodium-ion complexes were determined by a collision-activated decomposition (CAD) method utilizing electrospray ionization mass spectrometry (ESI-MS). Comparing the values of E(1/2), the collision energy at which the relative intensity of the complex ion is 0.5, we found that the porphyrin-calix[4]arene complex with the higher value of E(1/2) corresponded to that with the larger association constant (Kass), as measured by 1H-NMR in CDCl3. Both our ESI-MS and NMR studies proved that the number of hydrogen bonds and the rigidity of the calix[4]arene stabilized the complex. The ESI-MS technique could be successful in screening the binding affinity in host-guest systems with a small amount of sample.
authors.affiliation: Department of Applied Chemistry, School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Arai
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Ishihara
authors.forename: Shinji
authors.initials: S
authors.lastname: Takeoka
authors.forename: Haruki
authors.initials: H
authors.lastname: Ohkawa
authors.forename: Toshimichi
authors.initials: T
authors.lastname: Shibue
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nishide
mesh_terms: D000465:Algorithms; D047250:Calixarenes; D005740:Gases / Q000032:analysis / Q000737:chemistry; D007700:Kinetics; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008832:Microchemistry / Q000379:methods; D010636:Phenols / Q000032:analysis* / Q000737:chemistry*; D011166:Porphyrins / Q000032:analysis* / Q000737:chemistry*; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D005740:Gases; D046911:Macromolecular Substances; D010636:Phenols; D011166:Porphyrins; D011522:Protons; C121325:calix(4)arene; D047250:Calixarenes