Assignment of 1H NMR spectrum and investigation of oxidative degradation of poly(ethylenimine) using 1H and 13C 1‐D and 2‐D NMR

Idris, Salah A; Mkhatresh, Omar A; Heatley, Frank

doi:10.1002/pi.2049

Cited by 41 publications

(86 citation statements)

References 17 publications

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“…Integrated peaks of 13 C NMR spectra of BPEIs have been used to determine the amine ratio of B-PEIs in literature. [26, 27] However, the 13 C NMR spectra in Figure S3 may not be sufficiently accurate for comparing integrated areas because the data acquisition and NMR parameters were not optimized. Quantitative analysis would require more time-intensive data acquisition and further optimization of NMR parameters, which would be beyond the scope of this study.…”

Section: Resultsmentioning

confidence: 99%

Poly(ethylene imine)s as Antimicrobial Agents with Selective Activity

Gibney

Sovadinová

Lopez

et al. 2012

Macromolecular Bioscience

206

223

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We report the structure-activity relationship in the antimicrobial activity of linear and branched poly(ethylene imine)s (L- and B-PEIs) with a range of molecular weights (MWs) (500–12,000). Both L- and B-PEIs displayed enhanced activity against Staphylococcus aureus over Escherichia coli. Both B- and L-PEIs did not cause any significant permeabilization of E. coli cytoplasmic membrane. L-PEIs induced depolarization of S. aureus membrane although B-PEIs did not. The low MW B-PEIs caused little or no hemolysis while L-PEIs are hemolytic. The low MW B-PEIs are less cytotoxic to human HEp-2 cells than other PEIs. However, they induced significant cell viability reduction after 24 hours incubation. The results presented here highlight the interplay between polymer size and structure on activity.

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Section: Resultsmentioning

confidence: 99%

Poly(ethylene imine)s as Antimicrobial Agents with Selective Activity

Gibney

Sovadinová

Lopez

et al. 2012

Macromolecular Bioscience

206

223

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“…This solution was then titrated using 9.0 M aqueous HCl solution (dilution from 12 M HCl aqueous solution using D 2 O), and an aliquot was collected at every 0.5 unit change of pH during the titration and then used to acquire a 13 C NMR spectrum. A total of 24 13 C NMR spectra were obtained using a Varian MERCURY 300 MHz spectrometer with 64 transients each. The spectra were internally referenced to acetone at 30.89 ppm.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…A linear low molecular weight PEI oligomer (LLMW-PEI, with an average molecular weight of 423 Da) and two hyperbranched PEI polymers, including one with an average M n of 1.2 kDa (HB-PEI-1.2k) and the other with an average M n of 10 kDa (HB-PEI-10k), were utilized for the NMR studies reported here. 1D 1 H, 13 13 C} NMR experiments including HMQC, HMBC (heteronuclear multiple bond correlation), HMQCTOCSY ( 13 C filtered total correlation spectroscopy), and 2D 1 H{ 15 N} HMBC are also carried out for all three samples. In addition, the effect of pH on the position of 13 C NMR resonances was also investigated via a 13 C NMR-assisted titration, in order to deduce the protonation behavior of amino groups of PEI under different pH conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

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Comprehensive NMR Studies of the Structures and Properties of PEI Polymers

Holycross

Chai

2013

Macromolecules

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In this research, a suite of multinuclear and multidimensional NMR experiments such as 1D 1 H, 13 C, and 15 N NMR and 2D homonuclear 1 H− 1 H COSY, 2D heteronuclear 1 H{ 13 C} HMQC, HMBC, HMQC-TOCSY, and 2D heteronuclear 1 H{ 15 N} HMBC NMR were used to study a set of representative PEI polymers including hyperbranched polymers of high and low molecular weight and a low molecular weight linear oligomer. Furthermore, the protonation of the multiple unique basic sites of the low molecular weight hyperbranched PEI polymer was also studied through titration with 9.0 M aqueous hydrochloric acid solution and monitored in situ using 13 C NMR by tracking the change of 13 C chemical shifts as a function of pH during the titration. Such thorough NMR characterizations of PEI polymers can provide a comprehensive understanding of their structures and properties which may aid in more and better applications of these interesting polymers. ■ INTRODUCTIONCommercial poly(ethylene imine) (PEI) polymers are synthesized via acid-catalyzed cationic ring-opening polymerization of the ethylene imine monomer, which leads to a hyperbranched structure containing primary, secondary, and tertiary amino units. Linear PEI polymers are also commercially available which only contain secondary and primary (at the polymer chain end) amino groups in their structures. The multiple amino groups in PEI polymers make them useful as polyprotic bases and polydentate ligands in various applications. PEI polymers have been known and studied for three-quarters of a century, the first synthesis being patented in 1939. 1 Traditional uses for PEI included pulp dehydration in the paper industry and in fiber board production, as electrolyte extractors for zinc and cadmium plating, and as flocculants in coal production. 2 PEI polymers have also been used in water purification applications for the removal of heavy metal ions from water via complexation. 3,4 More recently, amphiphilic PEI polymers have been extensively used as DNA transfection agents due to their ability to form PEI/DNA complexes that are able to buffer the acidic environment of lysosomes and ultimately rupture the endosome, releasing the DNA. 5,6 Because of the high water solubility of these polymers, nanoparticles containing PEI have also been synthesized to enhance the solution stability and drug-release profiles for anticancer drug delivery. 7 As mentioned, PEI polymers have a number of versatile applications owing to their capability of forming complexes. pH is a crucial parameter for such a coordination process, and PEI complexes often show a distinct chemical behavior compared with analogous low molecular weight amine complexes due to the ability of the branched structure to conform to whatever shape is necessary for chelation. 4 For example, in a recent study, a new branched poly(ethylene imine) (PEI) resin was synthesized and characterized for selective extraction of boron from aqueous solutions. 8 As a result of the many functional sites available in the branched PEI structure, this novel...

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“…2(b)), the PRA conjugates evidenced distinctive peaks of both PEI and ATRA. A more detailed peak analysis of PRA5 is represented as follows: [31][32][33][34]. However, there is a difficulty in that the NMR method distinguishes PRA from a mixture of PEI and ATRA, although the dialysis method was utilized to obtain pure RPA.…”

Section: Synthesis and Characteristics Of Pramentioning

confidence: 99%