Mass spectrometry characterization of 3‐OH butyrated β‐cyclodextrin

Abstract

Oligo(3‐OH butyrate)‐β‐cyclodextrin esters (PHB‐CD) were obtained through ring opening of β‐butyrolactone (β‐BL) in the presence of β‐cyclodextrin (CD) and (‐)‐sparteine (SP) as nucleophilic activator. The resulted reaction mixture was first separated in two fractions and then investigated through a deep mass spectrometry (MS) study performed on a liquid chromatography‐electrospray ionization‐quadrupole time of flight (LC‐ESI‐QTOF) instrument. LC MS and tandem MS structural assignment of the reaction products was completed by NMR. The performed analysis revealed that poly(3‐OH butyrate) homopolymers (PHB) are formed together with the PHB‐CD products. Secondary reactions resulting in the formation of crotonates were also proved to occur. A comparison between MS and NMR results demonstrated that more than one PHB oligomer is attached to the CD in the PHB‐CD product. The tandem MS fragmentation studies validated the proposed structure of CD derivatives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Structural Architectural Features of Cyclodextrin Oligoesters Revealed by Fragmentation Mass Spectrometry Analysis

“…There was also a fragment peak situated at m / z = 1409 which may be formed by two simultaneous losses of 162 Da either by the G pathway alone (2 glycoside units), either by mixed fragmentations via G and E2 pathways, or solely via E2 by two concomitant losses of oligolactide chains each having a mass of 162 Da. The simultaneous loss of oligoester moieties attached to the CD was also observed in the case of CD modified with 3-OH butyrates [ 25 ]. In that case, the alternative fragmentation products were not isobaric peaks and therefore they were clearly observed.…”

“…The 1 H NMR analysis may give information about the structure of the compounds (chemical nature), about the site of the esterification (at the OH groups from the second, third, or sixth position of the glycoside ring), about the length of the oligolactide chains, and possibly about the total number of LA monomer units attached to the CD [ 15 , 18 ].…”

“…The classical chemistry methods employed so far for polymerization of cyclic esters initiated by CDs used catalysts commonly used in ROP, such as Sn-octoate [ 9 , 10 , 11 ] or amines-based organic catalysts [ 12 , 13 , 14 , 15 ]. However, there is one particular polymerization reaction that uses the special inclusion properties of the CD molecules.…”

“…The CD-oligoester derivatives have been characterized by MALDI MS [ 12 , 13 , 16 , 18 ] or ESI MS [ 15 , 19 , 24 , 25 ] for the structural assignment of the products. However, complex structure identification requires more than a single-stage MS measurement.…”

“…Detection and interpretation of the fragmentation spectra ions allows reconstruction of the primary structure (connectivity) of the selected polymer architecture in the case of polyesters [ 26 , 27 , 28 , 29 ]. Such fragmentation studies were applied in the case of CD modified with 3-OH-butyrates [ 15 , 25 ] obtained by ROP of β-butyrolactone catalyzed by (−)-sparteine.…”